Backwash Causes Lift? [Archive]

Dudley Henriques[_2_]

October 3rd 07, 03:23 AM

Le Chaud Lapin wrote:
> Hi,
>
> Student pilot here, self-teaching using the Jeppensen Private Pilot
> Kit after taking ground school. :D
>
> I read in the book that combustion "creates" energy, which is
> technically not true, but I decided to ignore it since the pictures
> are sooo pretty.
>
> Now, in Chapter 3, section about airfoils, it actually says:
>
> "In addition to the lowered pressure, a downward-backward flow of air
> also is generated from the top surface of the wing. The reaction to
> this downwash results in an upward force on the wing which demnstrates
> Newtons' third law of motion. This action/reaction principle also is
> apparent as the airstream strikes the lwoer surface of the wing when
> inclinded at a small angle (the angle of attack) to its direction of
> motion. The air is forced downward and therefore causes an upward
> reaction resulting in positive lift."
>
> IMHO, the latter part of this paragraph is correct, but the former
> part is wrong.
>
> Obviously, any air above the wing can only result in a force downward
> on top of the wing. The only force causing the plane to want to move
> upward comes from beneath the wing. The effect of any air above the
> wing is to cause rarefication above the wing, resulting in lower
> pressure, thereby giving the 14.7lbs/in^2 (plus) to do its work. That
> "reaction" coming from downward movement of air seems just plain silly
> to me.
>
> I am also inclined to take issue with the explanations of Bernouilli's
> Principle which I see often in the literature, but that's a different
> subject. [Note, I don't doubt Bernouilli's Principle, I just think
> there is more to it than the way it is being described in context of
> flying.]
>
> -Le Chaud Lapin-
>

Please don't take this the wrong way but I'm sure you would have passed
me up as a potential flight instructor.
:-))))

--
Dudley Henriques

Le Chaud Lapin

October 3rd 07, 03:37 AM

On Oct 2, 9:06 pm, "Dan Luke" > wrote:
> "Le Chaud Lapin" wrote:
> > Obviously, any air above the wing can only result in a force downward
> > on top of the wing. The only force causing the plane to want to move
> > upward comes from beneath the wing. The effect of any air above the
> > wing is to cause rarefication above the wing, resulting in lower
> > pressure, thereby giving the 14.7lbs/in^2 (plus) to do its work. That
> > "reaction" coming from downward movement of air seems just plain silly
> > to me.
>
> Then why does the wing stall and cease lifting when flow separates from the
> upper surface?

Because the situation of rarefication no longer exists during a stall,
or is significantly abated.

When plane is on the ramp, pressure above and below the wing are
equivalent.

When plane is flying certain critical speed, there is, IMO, pinching
that occurs at the leading edge of wing. This area of high pressure
results in a tendency for air to flow away from that pressure point in
all directions.

1. Flowing forward is not an option - that would make pressure
situation worse.
2. Flowing backward, toward the empennage, is not an option. The
leading edge of wing is there.
3. Flowing upward is possible, since above-the-pressure-point pressure
is less than that induced at pressure point.
4. Flowing backward is possible, since below-the-pressure-point
pressure is less than that induced at pressure point.

But here is the catch. If you take an umbrella, open it, find a friend
with extremely long arms, and ask him to yank the umbrella toward his
torso in one, quick, abrupt motion, he will feel a force immediately.
The umbrella might even invert if the impulse is strong enough.
[Sidenote: In the 1970's, I convinced small children that they could
fly if they jumped of 7ft brick wall with umbrella. Very amusing to
see their faces when they hit ground going just about as fast as they
would have without umbrella.] The force that is felt is due to
pressure building under the curved part of umbrella. But even if the
pressure did not build from compression, a force would still be felt,
becaue the force that was equalizing the pressure under the curved
part will have been removed.

And now the $1,000,000 point:

The air on the "outside" of the umbrella does *NOT* instantaneously
fill the void that is created by yanking the umbrella. A finite
amount of time is required for such air to rush in. If the unbrella
is pulled at even a low speed, the net effect can be felt. Pull it
fast enough, and it will invert or snap.

This is, IMO, a more illustrative way of looking at aerodynamics above
the wing than the canned Bernouilli speech.

1. The pinchage creates pressure.
2. A void is created over the wing, provided that plane is moving fast
enough that air high above win cannot rush in.
3. Air at back of wing participates in futile effort to fill the void.

But the most important thing is the pinchage. That pinching results
in high net speed of air molecules backward. Any air above wing that
tries to rush in and fill void is bombarded backward before it can
"touch" the upper surface of wing. I speculated that, if this point a
view were correct, gliders should have short chords with very long
spans, which, of course, is true.

About stalling:

When the angle of attack is too great, the pinchage is still present,
and depending on the shape of the leading edge, the backward flow is
still pressent, but not at the right angle relative to wing, and
certainly not flowing backward enough to stop the onrush of air coming
from above at back of wing. In the air comes, rushing in, and
pressure builds on top of wing.

But there is an ace in hole. Some books say that a plane will stall
if AOA is above critical angle. I do not think this is quite true. It
would seem that, worst-case-scenario, the dynamics above the wing
become royal mess at huge AOA. However, that mess will be less than
static pressure, and there will still be compression beneath the wing.
So if thrust is great enough, airplane should be able to do whatever
it wants.

-Le Chaud Lapin-

Bertie the Bunyip[_19_]

October 3rd 07, 04:23 AM

Le Chaud Lapin > wrote in
oups.com:

> On Oct 2, 9:06 pm, "Dan Luke" > wrote:
>> "Le Chaud Lapin" wrote:
>> > Obviously, any air above the wing can only result in a force
>> > downward on top of the wing. The only force causing the plane to
>> > want to move upward comes from beneath the wing. The effect of any
>> > air above the wing is to cause rarefication above the wing,
>> > resulting in lower pressure, thereby giving the 14.7lbs/in^2 (plus)
>> > to do its work. That "reaction" coming from downward movement of
>> > air seems just plain silly to me.
>>
>> Then why does the wing stall and cease lifting when flow separates
>> from the upper surface?
>
> Because the situation of rarefication no longer exists during a stall,
> or is significantly abated.
>
> When plane is on the ramp, pressure above and below the wing are
> equivalent.
>
> When plane is flying certain critical speed, there is, IMO, pinching
> that occurs at the leading edge of wing. This area of high pressure
> results in a tendency for air to flow away from that pressure point in
> all directions.
>
> 1. Flowing forward is not an option - that would make pressure
> situation worse.
> 2. Flowing backward, toward the empennage, is not an option. The
> leading edge of wing is there.
> 3. Flowing upward is possible, since above-the-pressure-point pressure
> is less than that induced at pressure point.
> 4. Flowing backward is possible, since below-the-pressure-point
> pressure is less than that induced at pressure point.
>
> But here is the catch. If you take an umbrella, open it, find a friend
> with extremely long arms, and ask him to yank the umbrella toward his
> torso in one, quick, abrupt motion, he will feel a force immediately.
> The umbrella might even invert if the impulse is strong enough.
> [Sidenote: In the 1970's, I convinced small children that they could
> fly if they jumped of 7ft brick wall with umbrella. Very amusing to
> see their faces when they hit ground going just about as fast as they
> would have without umbrella.] The force that is felt is due to
> pressure building under the curved part of umbrella. But even if the
> pressure did not build from compression, a force would still be felt,
> becaue the force that was equalizing the pressure under the curved
> part will have been removed.
>
> And now the $1,000,000 point:
>
> The air on the "outside" of the umbrella does *NOT* instantaneously
> fill the void that is created by yanking the umbrella. A finite
> amount of time is required for such air to rush in. If the unbrella
> is pulled at even a low speed, the net effect can be felt. Pull it
> fast enough, and it will invert or snap.
>
> This is, IMO, a more illustrative way of looking at aerodynamics above
> the wing than the canned Bernouilli speech.

Nope, it's not the same at all.
>
> 1. The pinchage creates pressure.
> 2. A void is created over the wing, provided that plane is moving fast
> enough that air high above win cannot rush in.
> 3. Air at back of wing participates in futile effort to fill the void.
>
> But the most important thing is the pinchage. That pinching results
> in high net speed of air molecules backward. Any air above wing that
> tries to rush in and fill void is bombarded backward before it can
> "touch" the upper surface of wing. I speculated that, if this point a
> view were correct, gliders should have short chords with very long
> spans, which, of course, is true.
>
> About stalling:
>
> When the angle of attack is too great, the pinchage is still present,
> and depending on the shape of the leading edge, the backward flow is
> still pressent, but not at the right angle relative to wing, and
> certainly not flowing backward enough to stop the onrush of air coming
> from above at back of wing. In the air comes, rushing in, and
> pressure builds on top of wing.
>
> But there is an ace in hole. Some books say that a plane will stall
> if AOA is above critical angle. I do not think this is quite true.

It's precisely true since th ecritical angle is defined by the stall.

Bertie

Bertie the Bunyip[_19_]

October 3rd 07, 04:24 AM

Dudley Henriques > wrote in news:DaednT-q-
:

> Le Chaud Lapin wrote:
>> Hi,
>>
>> Student pilot here, self-teaching using the Jeppensen Private Pilot
>> Kit after taking ground school. :D
>>
>> I read in the book that combustion "creates" energy, which is
>> technically not true, but I decided to ignore it since the pictures
>> are sooo pretty.
>>
>> Now, in Chapter 3, section about airfoils, it actually says:
>>
>> "In addition to the lowered pressure, a downward-backward flow of air
>> also is generated from the top surface of the wing. The reaction to
>> this downwash results in an upward force on the wing which
demnstrates
>> Newtons' third law of motion. This action/reaction principle also is
>> apparent as the airstream strikes the lwoer surface of the wing when
>> inclinded at a small angle (the angle of attack) to its direction of
>> motion. The air is forced downward and therefore causes an upward
>> reaction resulting in positive lift."
>>
>> IMHO, the latter part of this paragraph is correct, but the former
>> part is wrong.
>>
>> Obviously, any air above the wing can only result in a force downward
>> on top of the wing. The only force causing the plane to want to move
>> upward comes from beneath the wing. The effect of any air above the
>> wing is to cause rarefication above the wing, resulting in lower
>> pressure, thereby giving the 14.7lbs/in^2 (plus) to do its work. That
>> "reaction" coming from downward movement of air seems just plain
silly
>> to me.
>>
>> I am also inclined to take issue with the explanations of
Bernouilli's
>> Principle which I see often in the literature, but that's a different
>> subject. [Note, I don't doubt Bernouilli's Principle, I just think
>> there is more to it than the way it is being described in context of
>> flying.]
>>
>> -Le Chaud Lapin-
>>
>
> Please don't take this the wrong way but I'm sure you would have
passed
> me up as a potential flight instructor.
>:-))))
>
>

I nominate Anthony!

Bertie

george

October 3rd 07, 04:33 AM

On Oct 3, 1:57 pm, Le Chaud Lapin > wrote:

> "In addition to the lowered pressure, a downward-backward flow of air
> also is generated from the top surface of the wing. The reaction to
> this downwash results in an upward force on the wing which demnstrates
> Newtons' third law of motion. This action/reaction principle also is
> apparent as the airstream strikes the lwoer surface of the wing when
> inclinded at a small angle (the angle of attack) to its direction of
> motion. The air is forced downward and therefore causes an upward
> reaction resulting in positive lift."

I blame the lift pixies myself

Le Chaud Lapin

October 3rd 07, 05:20 AM

On Oct 2, 10:23 pm, Bertie the Bunyip > wrote:
> > But there is an ace in hole. Some books say that a plane will stall
> > if AOA is above critical angle. I do not think this is quite true.
>
> It's precisely true since th ecritical angle is defined by the stall.

What is the definition of a stall anyway?

I'm saying that, if you take a plane with certain critical angle,
throw away engine, put on an engine that can generate 10x the thrust,
the plane should still fly, even if you exceed critical angle.

These books imply that the critical angle is angle at with bad things
happen above the wing, and because of that, the plane will fall. I'm
saying that, you can have all the bad things happen above the wing and
still be able to keep the plane aloft due to compression that occurs
beneath the wing.

Of course, I have only been doing this officially 7 weeks, so I might
be wrong. ;)

-Le Chaud Lapin-

Le Chaud Lapin

October 3rd 07, 05:23 AM

On Oct 2, 10:33 pm, george > wrote:
> On Oct 3, 1:57 pm, Le Chaud Lapin > wrote:
>
> > "In addition to the lowered pressure, a downward-backward flow of air
> > also is generated from the top surface of the wing. The reaction to
> > this downwash results in an upward force on the wing which demnstrates
> > Newtons' third law of motion. This action/reaction principle also is
> > apparent as the airstream strikes the lwoer surface of the wing when
> > inclinded at a small angle (the angle of attack) to its direction of
> > motion. The air is forced downward and therefore causes an upward
> > reaction resulting in positive lift."
>
> I blame the lift pixies myself

LOL.

This flying business is a bit too fascinating. I'm having trouble
concentrating on my day job. In no other hobby has the opportunity
arisen to apply essentially everything technical I have ever learned.
Physics, chemistry, mathematics, electronics, computation...it's all
there.

-Le Chaud Lapin-

Le Chaud Lapin

October 3rd 07, 05:28 AM

On Oct 2, 10:24 pm, Bertie the Bunyip > wrote:
> > Please don't take this the wrong way but I'm sure you would have
> passed
> > me up as a potential flight instructor.
> >:-))))
>
> I nominate Anthony!

Heh.

I knew going into ground school that the focus would be flying, not
aero/astro, so I was not disappointed with the course. By rushing us,
the instructor gave us a broad overview of what we should know. This
has been hugely beneficial for my learning.

Makes going through it again, slowly, with physics book nearby very
pleasurable.

-Le Chaud Lapin-

Mxsmanic

October 3rd 07, 05:54 AM

Le Chaud Lapin writes:

> Obviously, any air above the wing can only result in a force downward
> on top of the wing. The only force causing the plane to want to move
> upward comes from beneath the wing. The effect of any air above the
> wing is to cause rarefication above the wing, resulting in lower
> pressure, thereby giving the 14.7lbs/in^2 (plus) to do its work. That
> "reaction" coming from downward movement of air seems just plain silly
> to me.

Lift is a reaction to the force required to push air downward behind the wing
(downwash). How the air gets pushed downward is not very important. The wing
twists air into a downwash as it passes through it, leaving a swath of air
moving gently downward behind it. The force required to do this engenders an
equal and opposite force that is lift. Lift accelerates the wing upward,
counteracting gravity. The wing accelerates a large mass of air downward.

> I am also inclined to take issue with the explanations of Bernouilli's
> Principle which I see often in the literature, but that's a different
> subject. [Note, I don't doubt Bernouilli's Principle, I just think
> there is more to it than the way it is being described in context of
> flying.]

There are a lot of different ways to examine and describe the aerodynamics of
lift. It boils down to accelerating one mass (a mass of air) downward, which
engenders another acceleration of another mass (the wing, and anything to
which it is attached) upward. Any flat surface moving relative to the air
with a positive angle of attack below the stall angle will generate lift.

Mxsmanic

October 3rd 07, 05:54 AM

Dan Luke writes:

> Then why does the wing stall and cease lifting when flow separates from the
> upper surface?

Because it is no longer accelerating air efficiently downward.

Mxsmanic

October 3rd 07, 05:56 AM

Le Chaud Lapin writes:

> However, that mess will be less than
> static pressure, and there will still be compression beneath the wing.
> So if thrust is great enough, airplane should be able to do whatever
> it wants.

Pressure beneath the wing is not what lifts the aircraft. It's the twisting
acceleration of air above the wing downward that results in lift.

Mxsmanic

October 3rd 07, 05:58 AM

Le Chaud Lapin writes:

> What is the definition of a stall anyway?

An abrupt loss of lift.

> I'm saying that, if you take a plane with certain critical angle,
> throw away engine, put on an engine that can generate 10x the thrust,
> the plane should still fly, even if you exceed critical angle.

No, the thrust of the engine doesn't matter, unless the engine itself is
supporting the weight of the aircraft with thrust (possible in a few fighter
aircraft). A wing above the critical angle will stall at any speed.

> These books imply that the critical angle is angle at with bad things
> happen above the wing, and because of that, the plane will fall.

Yes, true.

> I'm saying that, you can have all the bad things happen above the wing and
> still be able to keep the plane aloft due to compression that occurs
> beneath the wing.

The wing is not supported by compression. It is supported by the displacement
of a mass (of air) downward. If this displacement ceases to take place, lift
disappears. A stalled wing does not divert air downward, so it doesn't
generate lift.

Bertie the Bunyip[_19_]

October 3rd 07, 07:36 AM

Mxsmanic > wrote in
:

> Le Chaud Lapin writes:
>
>> What is the definition of a stall anyway?
>
> An abrupt loss of lift.
>
>> I'm saying that, if you take a plane with certain critical angle,
>> throw away engine, put on an engine that can generate 10x the thrust,
>> the plane should still fly, even if you exceed critical angle.
>
> No, the thrust of the engine doesn't matter, unless the engine itself
> is supporting the weight of the aircraft with thrust (possible in a
> few fighter aircraft). A wing above the critical angle will stall at
> any speed.
>
>> These books imply that the critical angle is angle at with bad things
>> happen above the wing, and because of that, the plane will fall.
>
> Yes, true.
>
>> I'm saying that, you can have all the bad things happen above the
>> wing and still be able to keep the plane aloft due to compression
>> that occurs beneath the wing.
>
> The wing is not supported by compression. It is supported by the
> displacement of a mass (of air) downward. If this displacement ceases
> to take place, lift

This should be entertaining.

Bertie

Bertie the Bunyip[_19_]

October 3rd 07, 07:37 AM

Mxsmanic > wrote in
:

> Le Chaud Lapin writes:
>
>> However, that mess will be less than
>> static pressure, and there will still be compression beneath the
>> wing. So if thrust is great enough, airplane should be able to do
>> whatever it wants.
>
> Pressure beneath the wing is not what lifts the aircraft. It's the
> twisting acceleration of air above the wing downward that results in
> lift.
>

No, it isn't, fjukkktard.

Unless the rules of physics have changed.

Bertie

Bertie the Bunyip[_19_]

October 3rd 07, 07:38 AM

Mxsmanic > wrote in
:

> Le Chaud Lapin writes:
>
>> Obviously, any air above the wing can only result in a force downward
>> on top of the wing. The only force causing the plane to want to move
>> upward comes from beneath the wing. The effect of any air above the
>> wing is to cause rarefication above the wing, resulting in lower
>> pressure, thereby giving the 14.7lbs/in^2 (plus) to do its work. That
>> "reaction" coming from downward movement of air seems just plain
>> silly to me.
>
> Lift is a reaction to the force required to push air downward behind
> the wing (downwash). How the air gets pushed downward is not very
> important. The wing twists air into a downwash as it passes through
> it, leaving a swath of air moving gently downward behind it. The
> force required to do this engenders an equal and opposite force that
> is lift. Lift accelerates the wing upward, counteracting gravity.
> The wing accelerates a large mass of air downward.
>
>> I am also inclined to take issue with the explanations of
>> Bernouilli's Principle which I see often in the literature, but
>> that's a different subject. [Note, I don't doubt Bernouilli's
>> Principle, I just think there is more to it than the way it is being
>> described in context of flying.]
>
> There are a lot of different ways to examine and describe the
> aerodynamics of lift. It boils down to accelerating one mass (a mass
> of air) downward, which engenders another acceleration of another mass
> (the wing, and anything to which it is attached) upward. Any flat
> surface moving relative to the air with a positive angle of attack
> below the stall angle will generate lift.
>

Nope.

Bertie

Tina

October 3rd 07, 09:50 AM

It is clearly time to revisit airplanes taking off on tredmills.

Bertie the Bunyip[_19_]

October 3rd 07, 09:59 AM

Tina > wrote in news:1191401433.827965.190080
@o80g2000hse.googlegroups.com:

> It is clearly time to revisit airplanes taking off on tredmills.
>
>
>

Do tell. Must have been before my time here.

Bertie

Matt Whiting

October 3rd 07, 11:32 AM

Dan Luke wrote:
> "Le Chaud Lapin" wrote:
>
>> Obviously, any air above the wing can only result in a force downward
>> on top of the wing. The only force causing the plane to want to move
>> upward comes from beneath the wing. The effect of any air above the
>> wing is to cause rarefication above the wing, resulting in lower
>> pressure, thereby giving the 14.7lbs/in^2 (plus) to do its work. That
>> "reaction" coming from downward movement of air seems just plain silly
>> to me.
>
>
> Then why does the wing stall and cease lifting when flow separates from the
> upper surface?
>
>

It doesn't cease lifting. It doesn't lift as hard, and not hard enough
to support the airplane, but the force doesn't magically go away.

Matt

gpaleo

October 3rd 07, 12:06 PM

Ï "Le Chaud Lapin" > Ýãñáøå óôï ìÞíõìá
ups.com...
>
> Hi,
>
> Student pilot here, self-teaching using the Jeppensen Private Pilot
> Kit after taking ground school. :D
..................................................
>> there is more to it than the way it is being described in context of
> flying.]
>
> -Le Chaud Lapin-

Hot Bunny ??????????????
ROTFLMAO

BDS[_2_]

October 3rd 07, 01:27 PM

"Mxsmanic" > wrote
> Le Chaud Lapin writes:
>
> > What is the definition of a stall anyway?
>
> An abrupt loss of lift.

Son, for someone who continually chastises the pilots here for their lack of
knowledge, you sure can come up with some doozies yourself!

BDS

Dudley Henriques[_2_]

October 3rd 07, 02:15 PM

Bertie the Bunyip wrote:
> Dudley Henriques > wrote in news:DaednT-q-
> :
>
>> Le Chaud Lapin wrote:
>>> Hi,
>>>
>>> Student pilot here, self-teaching using the Jeppensen Private Pilot
>>> Kit after taking ground school. :D
>>>
>>> I read in the book that combustion "creates" energy, which is
>>> technically not true, but I decided to ignore it since the pictures
>>> are sooo pretty.
>>>
>>> Now, in Chapter 3, section about airfoils, it actually says:
>>>
>>> "In addition to the lowered pressure, a downward-backward flow of air
>>> also is generated from the top surface of the wing. The reaction to
>>> this downwash results in an upward force on the wing which
> demnstrates
>>> Newtons' third law of motion. This action/reaction principle also is
>>> apparent as the airstream strikes the lwoer surface of the wing when
>>> inclinded at a small angle (the angle of attack) to its direction of
>>> motion. The air is forced downward and therefore causes an upward
>>> reaction resulting in positive lift."
>>>
>>> IMHO, the latter part of this paragraph is correct, but the former
>>> part is wrong.
>>>
>>> Obviously, any air above the wing can only result in a force downward
>>> on top of the wing. The only force causing the plane to want to move
>>> upward comes from beneath the wing. The effect of any air above the
>>> wing is to cause rarefication above the wing, resulting in lower
>>> pressure, thereby giving the 14.7lbs/in^2 (plus) to do its work. That
>>> "reaction" coming from downward movement of air seems just plain
> silly
>>> to me.
>>>
>>> I am also inclined to take issue with the explanations of
> Bernouilli's
>>> Principle which I see often in the literature, but that's a different
>>> subject. [Note, I don't doubt Bernouilli's Principle, I just think
>>> there is more to it than the way it is being described in context of
>>> flying.]
>>>
>>> -Le Chaud Lapin-
>>>
>> Please don't take this the wrong way but I'm sure you would have
> passed
>> me up as a potential flight instructor.
>> :-))))
>>
>>
>
> I nominate Anthony!
>
> Bertie
>

Nah.....Anthony has offered many times to teach me about aerodynamics
and flying but so far at least I've cleverly managed to avoid that
enlightening experience.
:-))

--
Dudley Henriques

Tina

October 3rd 07, 02:25 PM

Then there's the Mx medical advice column, physics advice -- I'm
waiting for a unified field theory, or maybe a proposed standard of
care for depression.

I had a thought for what would be the longest thread ever in this
newsgroup -- "The collected corrections of Mx statements". Bertie
could be its editor, he has a deft and gentle way of pointing out
errors.

Tina

October 3rd 07, 02:39 PM

You wrote

On Oct 2, 9:57 pm, Le Chaud Lapin > wrote:
> Hi,
>
> Student pilot here, self-teaching using the Jeppensen Private Pilot
> Kit after taking ground school. :D
>
> I read in the book that combustion "creates" energy, which is
> technically not true, but I decided to ignore it since the pictures
> are sooo pretty.
>
> Now, in Chapter 3, section about airfoils, it actually says:
>
> "In addition to the lowered pressure, a downward-backward flow of air
> also is generated from the top surface of the wing. The reaction to
> this downwash results in an upward force on the wing which demnstrates
> Newtons' third law of motion. This action/reaction principle also is
> apparent as the airstream strikes the lwoer surface of the wing when
> inclinded at a small angle (the angle of attack) to its direction of
> motion. The air is forced downward and therefore causes an upward
> reaction resulting in positive lift."
>
> IMHO, the latter part of this paragraph is correct, but the former
> part is wrong.
>
> Obviously, any air above the wing can only result in a force downward
> on top of the wing. The only force causing the plane to want to move
> upward comes from beneath the wing. The effect of any air above the
> wing is to cause rarefication above the wing, resulting in lower
> pressure, thereby giving the 14.7lbs/in^2 (plus) to do its work. That
> "reaction" coming from downward movement of air seems just plain silly
> to me.

You would do well to think in terms of differential pressure. If one
can by some means cause the pressure on the upper surface of the wing
to be 1 psi less than the pressure on the lower surface, there would
be an upward force on the wing of the order of 144 pounds per square
foot (my physics training, a million years ago, was in english units).

You might also want to think carefully about airfoil shapes, since
wings can provide lift when flying inverted. Any theory that does not
support inverted flight is obviously flawed.

But the neat thing to do is to hold your hand out of a moving car's
window, and feel the impact pressure on its surfaces as you tilt it in
the airstream. It's not that the hand is being "sucked" up, you don't
feel suction on the top surface, you feel push on the bottom one. Any
theory you develop had better be consistant with those observations.
Someone with more time than I have might like to start with the fact
that air weighs about .08 pounds per square foot near sea level, and
crack some numbers to show how that deflecting that mass can result in
lift even if the lifting surface has some funny shapes.

Le Chaud Lapin

October 3rd 07, 03:15 PM

On Oct 3, 8:39 am, Tina > wrote:
> You might also want to think carefully about airfoil shapes, since
> wings can provide lift when flying inverted. Any theory that does not
> support inverted flight is obviously flawed.

Actually I did because every book I read about flying skimped on the
subject. I'm going to hop over to MIT's OpenCourseWare later this
week and download their most basic course on aero/astro. Benoulli's
principle is toss around as if it were facecloth, but I'm getting the
feeling that no one is really doing the physics.

> But the neat thing to do is to hold your hand out of a moving car's
> window, and feel the impact pressure on its surfaces as you tilt it in
> the airstream. It's not that the hand is being "sucked" up, you don't
> feel suction on the top surface, you feel push on the bottom one. Any
> theory you develop had better be consistant with those observations.
> Someone with more time than I have might like to start with the fact
> that air weighs about .08 pounds per square foot near sea level, and
> crack some numbers to show how that deflecting that mass can result in
> lift even if the lifting surface has some funny shapes.- Hide quoted text -

Yes it is. In fact, I was having this discussion with someone who
claimed that it *was* Benoulli's principle only. I made the following
diagram to try to illustrate my point. View in fixed width

| inverted |
| table |
|--------------------|

|--------------------|
| upright |
| table |

The Bernoulli people often describe air flowing above the a table
being faster than air below a table, and therefore, pressure is
reduced. Hmmm... what happens if the horizontal velocities above and
below a table are both essentially 0?

If you place an inverted table on top of an upright table so that the
table tops are mated, then have a machine, with a tremendous amount of
force, on the order of 14.4lbs/in^2 of force, yank the inverted table
upward, in one quick jerk, I contend that the lower table will be
strongly inclined to follow by jumping updward, obviously due to
pressure beneath it. So any type of rarefication on one side of a
doubly-pressurized surface that is free to move in direction that is
perpendicular to the surface, will, indeed, move, if pressure is
reduced.

And this is why, I am pretty sure, that if I were to search the web,
one would find people who are fanatical about the leading edges of
wings, in the most minute detail, because it is not simply the length
of the top of the wing that matters, but the amount of pinching, and
the distribution of air as it flows backward from the pressure point.
IMO, that pinching results in displacement of the air above to make it
effective go backwares, causing rarefication.

-Le Chaud Lapin-

Dudley Henriques[_2_]

October 3rd 07, 03:27 PM

Tina wrote:
> Then there's the Mx medical advice column, physics advice -- I'm
> waiting for a unified field theory, or maybe a proposed standard of
> care for depression.
>
> I had a thought for what would be the longest thread ever in this
> newsgroup -- "The collected corrections of Mx statements". Bertie
> could be its editor, he has a deft and gentle way of pointing out
> errors.
>
>

I love Bertie's personal rendition of Occam's Razor to Anthony's long
extended posts where he "explains" everything in intimate and minute detail.

"Nope"!

--
Dudley Henriques

[email protected]

October 3rd 07, 04:34 PM

On Oct 3, 8:15 am, Le Chaud Lapin > wrote:

> Actually I did because every book I read about flying skimped on the
> subject. I'm going to hop over to MIT's OpenCourseWare later this
> week and download their most basic course on aero/astro. Benoulli's
> principle is toss around as if it were facecloth, but I'm getting the
> feeling that no one is really doing the physics.

Lemme see: People have been building flying machines since the late
1800's, about 125 years now, and none of them have been interested
enough in the phenomenon of lift to do the physics? How old are you,
anyway? Many of the contributors here have been flying much longer
than you have likely been alive and have studied this in detail, and
some of them might even have doctorates in the subject. The subject of
lift has been beaten to death on this forum and if you Googled it
you'd find some good information.
Both Newton and Bernoulli are correct. Even inside a pipe the
static pressure drops as velocity increases. That's why your bottom
table jumps as you yank off the top one: you accelerated an airflow.
And in generating lift there's a displacement of air. Can't escape
that at all.
The stagnation point on a leading edge isn't right at the front.
It's slightly below the wing, and as AOA increases it moves back
underneath quite a bit. It's not all intuitive, you see, and that
intuitive understanding of some of this stuff is where people get all
messed up and think they have the answers that have escaped all the
other experts all these years. We run into this attitude rather
frequently in the flight training industry. It tends to make the
student unteachable.

Dan

Bertie the Bunyip[_19_]

October 3rd 07, 04:37 PM

Dudley Henriques > wrote in
:

> Bertie the Bunyip wrote:
>> Dudley Henriques > wrote in news:DaednT-q-
>> :
>>
>>> Le Chaud Lapin wrote:
>>>> Hi,
>>>>
>>>> Student pilot here, self-teaching using the Jeppensen Private Pilot
>>>> Kit after taking ground school. :D
>>>>
>>>> I read in the book that combustion "creates" energy, which is
>>>> technically not true, but I decided to ignore it since the pictures
>>>> are sooo pretty.
>>>>
>>>> Now, in Chapter 3, section about airfoils, it actually says:
>>>>
>>>> "In addition to the lowered pressure, a downward-backward flow of
air
>>>> also is generated from the top surface of the wing. The reaction to
>>>> this downwash results in an upward force on the wing which
>> demnstrates
>>>> Newtons' third law of motion. This action/reaction principle also
is
>>>> apparent as the airstream strikes the lwoer surface of the wing
when
>>>> inclinded at a small angle (the angle of attack) to its direction
of
>>>> motion. The air is forced downward and therefore causes an upward
>>>> reaction resulting in positive lift."
>>>>
>>>> IMHO, the latter part of this paragraph is correct, but the former
>>>> part is wrong.
>>>>
>>>> Obviously, any air above the wing can only result in a force
downward
>>>> on top of the wing. The only force causing the plane to want to
move
>>>> upward comes from beneath the wing. The effect of any air above
the
>>>> wing is to cause rarefication above the wing, resulting in lower
>>>> pressure, thereby giving the 14.7lbs/in^2 (plus) to do its work.
That
>>>> "reaction" coming from downward movement of air seems just plain
>> silly
>>>> to me.
>>>>
>>>> I am also inclined to take issue with the explanations of
>> Bernouilli's
>>>> Principle which I see often in the literature, but that's a
different
>>>> subject. [Note, I don't doubt Bernouilli's Principle, I just think
>>>> there is more to it than the way it is being described in context
of
>>>> flying.]
>>>>
>>>> -Le Chaud Lapin-
>>>>
>>> Please don't take this the wrong way but I'm sure you would have
>> passed
>>> me up as a potential flight instructor.
>>> :-))))
>>>
>>>
>>
>> I nominate Anthony!
>>
>> Bertie
>>
>
> Nah.....Anthony has offered many times to teach me about aerodynamics
> and flying but so far at least I've cleverly managed to avoid that
> enlightening experience.
>:-))
>

Be a bit like letting a jackhammer operator do your teeth, that.

Bertie

Bertie the Bunyip[_19_]

October 3rd 07, 04:38 PM

Tina > wrote in news:1191417912.483823.271490
@g4g2000hsf.googlegroups.com:

> Then there's the Mx medical advice column, physics advice -- I'm
> waiting for a unified field theory, or maybe a proposed standard of
> care for depression.
>
> I had a thought for what would be the longest thread ever in this
> newsgroup -- "The collected corrections of Mx statements". Bertie
> could be its editor, he has a deft and gentle way of pointing out
> errors.
>
>
>

He's an idiot, what else does one need to know?

Bertie

Bertie the Bunyip[_19_]

October 3rd 07, 04:48 PM

Le Chaud Lapin > wrote in
ups.com:

> On Oct 3, 8:39 am, Tina > wrote:
>> You might also want to think carefully about airfoil shapes, since
>> wings can provide lift when flying inverted. Any theory that does
>> not support inverted flight is obviously flawed.
>
> Actually I did because every book I read about flying skimped on the
> subject. I'm going to hop over to MIT's OpenCourseWare later this
> week and download their most basic course on aero/astro. Benoulli's
> principle is toss around as if it were facecloth, but I'm getting the
> feeling that no one is really doing the physics.

Well, NASA have and they wholeheartedly support Bernoulli , as do an
Airbus engineeer and a Boeing Engineer of my acquantence. NASA used to
have a whole web page debunking the Bernoulli deniers, but it sems to be
gone now.
It's pretty simple in how it relates to how the airplane flies from one
standpoint and complex from another, but at the end of the day it's how
your knowledge makes the airplane perfomr that counts, and the only
thing tha's going to teach you that is flying an airplane guided by a
good instructor.
If you try to understand it at a molecular level, you've got a problem,
as nobody really undertands lift completely (Here's anthony's chance to
go all creationist on us now)

>
>> But the neat thing to do is to hold your hand out of a moving car's
>> window, and feel the impact pressure on its surfaces as you tilt it
>> in the airstream. It's not that the hand is being "sucked" up, you
>> don't feel suction on the top surface, you feel push on the bottom
>> one. Any theory you develop had better be consistant with those
>> observations. Someone with more time than I have might like to start
>> with the fact that air weighs about .08 pounds per square foot near
>> sea level, and crack some numbers to show how that deflecting that
>> mass can result in lift even if the lifting surface has some funny
>> shapes.- Hide quoted text -
>
> Yes it is. In fact, I was having this discussion with someone who
> claimed that it *was* Benoulli's principle only. I made the following
> diagram to try to illustrate my point. View in fixed width
>
>
>| inverted |
>| table |
>|--------------------|
>
>|--------------------|
>| upright |
>| table |
>
> The Bernoulli people often describe air flowing above the a table
> being faster than air below a table, and therefore, pressure is
> reduced. Hmmm... what happens if the horizontal velocities above and
> below a table are both essentially 0?
>
> If you place an inverted table on top of an upright table so that the
> table tops are mated, then have a machine, with a tremendous amount of
> force, on the order of 14.4lbs/in^2 of force, yank the inverted table
> upward, in one quick jerk, I contend that the lower table will be
> strongly inclined to follow by jumping updward, obviously due to
> pressure beneath it. So any type of rarefication on one side of a
> doubly-pressurized surface that is free to move in direction that is
> perpendicular to the surface, will, indeed, move, if pressure is
> reduced.
>
> And this is why, I am pretty sure, that if I were to search the web,
> one would find people who are fanatical about the leading edges of
> wings, in the most minute detail, because it is not simply the length
> of the top of the wing that matters, but the amount of pinching, and
> the distribution of air as it flows backward from the pressure point.
> IMO, that pinching results in displacement of the air above to make it
> effective go backwares, causing rarefication.
>

That all sounds fairly sound, but it's too esoteric to relate to
handling an airplane well.

Don't forget, handling, and it's handling that is the aim of the
knowledge you seek, is primarily a right hand brain operation. If you
try to fly with too much of the left included, you are going to fly like
a chicken on crack.

Bertie
>
>
>

Le Chaud Lapin

October 3rd 07, 05:16 PM

On Oct 3, 10:34 am, wrote:
> Both Newton and Bernoulli are correct. Even inside a pipe the
> static pressure drops as velocity increases. That's why your bottom
> table jumps as you yank off the top one: you accelerated an airflow.
> And in generating lift there's a displacement of air. Can't escape
> that at all.

It is the removal of air from above the table that causes the lift.

If a person sucks on a straw, thus removing air from the inside of the
straw, the fluid rises into the straw from the container do to the air/
fluid system outside the straw. This is the same phenomenon that is
occurring in my table scenario. In fact, I could enclose the entire
table scenario inside a tube, and cause the bottom table to rise up
off the ground. This has nothing to do with the velocity or
acceleration of air.

> The stagnation point on a leading edge isn't right at the front.
> It's slightly below the wing, and as AOA increases it moves back
> underneath quite a bit. It's not all intuitive, you see, and that
> intuitive understanding of some of this stuff is where people get all
> messed up and think they have the answers that have escaped all the
> other experts all these years. We run into this attitude rather
> frequently in the flight training industry. It tends to make the
> student unteachable.

I do rely on intuition to figure things out, but most importantly, I'd
rather actually understand, than except shallow explanations.

I never attempted to contradict either Bernoulii or Newton. What I
keep saying is that I have seen too many situations where someone will
rattle of "Bernoulli's Principle" and not really understand it
themselves.

For example, as I mentioned earlier, I am reading Jeppesens Private
Pilot manual, and there are clearly errors in concept the manual
(energy being created by engine, for example), even though Jeppensen
probably has access to as many Ph.D. laureates as they want.

-Le Chaud Lapin-

Bertie the Bunyip[_19_]

October 3rd 07, 05:21 PM

"Dan Luke" > wrote in
:

>
> "Le Chaud Lapin" wrote:
>
>> Obviously, any air above the wing can only result in a force downward
>> on top of the wing. The only force causing the plane to want to move
>> upward comes from beneath the wing. The effect of any air above the
>> wing is to cause rarefication above the wing, resulting in lower
>> pressure, thereby giving the 14.7lbs/in^2 (plus) to do its work. That
>> "reaction" coming from downward movement of air seems just plain
>> silly to me.
>
>
> Then why does the wing stall and cease lifting when flow separates
> from the upper surface?
>
>

Actually, that's not the definition of the stall, seperation occurs just
after the stall with most airfoil/planform combinations and in most
flight situations, ordinarily. Some wings will have seperation at the
stall, but I've never flown one.
The defintion is an abrupt loss of lift when the critical angle is
reached. Seperation usually occurs immidiatly after (*but not always,
for instance, deltas will continue to have smooth flow way below he
point they will actually keep flying) This is not to be confused with
the back siide of the drag curve, BTW.
Having said all hat, there are some reputable design texts that define
stall as the point at which the bubble breaks down and buffet occurs and
as far as I know, this doesn't disturb engineers (of which I am not one,
BTW, so take this all with a large grain of salt) any more than a "po-
tay-to, po-tah-to" argument would.
Bottom line is you're interested in keeping your airplane from going
down and the point at which the wing ceases to do what you would like it
to do is the point at which you're most interested.

Make sense? If it does I must not have explained it well.

Bertie

Kloudy via AviationKB.com

October 3rd 07, 05:22 PM

Bertie the Bunyip wrote:

>like a chicken on crack.
>
>Bertie

Funny...I suspect you know what that looks like. ; )

--
Message posted via AviationKB.com
http://www.aviationkb.com/Uwe/Forums.aspx/aviation/200710/1

Bertie the Bunyip[_19_]

October 3rd 07, 05:24 PM

Le Chaud Lapin > wrote in
oups.com:

> On Oct 3, 10:34 am, wrote:
>> Both Newton and Bernoulli are correct. Even inside a pipe the
>> static pressure drops as velocity increases. That's why your bottom
>> table jumps as you yank off the top one: you accelerated an airflow.
>> And in generating lift there's a displacement of air. Can't escape
>> that at all.
>
> It is the removal of air from above the table that causes the lift.
>
> If a person sucks on a straw, thus removing air from the inside of the
> straw, the fluid rises into the straw from the container do to the
air/
> fluid system outside the straw. This is the same phenomenon that is
> occurring in my table scenario. In fact, I could enclose the entire
> table scenario inside a tube, and cause the bottom table to rise up
> off the ground. This has nothing to do with the velocity or
> acceleration of air.
>
>> The stagnation point on a leading edge isn't right at the
front.
>> It's slightly below the wing, and as AOA increases it moves back
>> underneath quite a bit. It's not all intuitive, you see, and that
>> intuitive understanding of some of this stuff is where people get all
>> messed up and think they have the answers that have escaped all the
>> other experts all these years. We run into this attitude rather
>> frequently in the flight training industry. It tends to make the
>> student unteachable.
>
> I do rely on intuition to figure things out, but most importantly, I'd
> rather actually understand, than except shallow explanations.
>
> I never attempted to contradict either Bernoulii or Newton. What I
> keep saying is that I have seen too many situations where someone will
> rattle of "Bernoulli's Principle" and not really understand it
> themselves.
>
> For example, as I mentioned earlier, I am reading Jeppesens Private
> Pilot manual, and there are clearly errors in concept the manual
> (energy being created by engine, for example), even though Jeppensen
> probably has access to as many Ph.D. laureates as they want.
>

Yes, well, you obviously need to write a good old fashioned, angry,
frothng at the mouth letter to Jeppeson. I'm sure Elry will be suitably
rattled.

Bertie

Bertie the Bunyip[_19_]

October 3rd 07, 05:28 PM

"Kloudy via AviationKB.com" <u33403@uwe> wrote in news:79253d6018083@uwe:

> Bertie the Bunyip wrote:
>
>>like a chicken on crack.
>>
>>Bertie
>
> Funny...I suspect you know what that looks like. ; )
>

Nah,I just have a good imagination.
Though if oyu send me some crack I do have some chickens I could try it on.

Bertie

[email protected]

October 3rd 07, 05:35 PM

wrote:
> On Oct 3, 8:15 am, Le Chaud Lapin > wrote:

> > Actually I did because every book I read about flying skimped on the
> > subject. I'm going to hop over to MIT's OpenCourseWare later this
> > week and download their most basic course on aero/astro. Benoulli's
> > principle is toss around as if it were facecloth, but I'm getting the
> > feeling that no one is really doing the physics.

> Lemme see: People have been building flying machines since the late
> 1800's, about 125 years now, and none of them have been interested
> enough in the phenomenon of lift to do the physics? How old are you,
> anyway? Many of the contributors here have been flying much longer
> than you have likely been alive and have studied this in detail, and
> some of them might even have doctorates in the subject. The subject of
> lift has been beaten to death on this forum and if you Googled it
> you'd find some good information.
> Both Newton and Bernoulli are correct. Even inside a pipe the
> static pressure drops as velocity increases. That's why your bottom
> table jumps as you yank off the top one: you accelerated an airflow.
> And in generating lift there's a displacement of air. Can't escape
> that at all.
> The stagnation point on a leading edge isn't right at the front.
> It's slightly below the wing, and as AOA increases it moves back
> underneath quite a bit. It's not all intuitive, you see, and that
> intuitive understanding of some of this stuff is where people get all
> messed up and think they have the answers that have escaped all the
> other experts all these years. We run into this attitude rather
> frequently in the flight training industry. It tends to make the
> student unteachable.

I think the main issue is that it doesn't require a Phd in physics to
fly an airplane and the explanations of lift, stall, drag, etc.
for pilots tend to be highly simplified, and rightfully so.

A full explanation that would satisfy a physisicist would likely
cause exterme eye glaze in the average pilot.

If one want's that level of insight, I would suggest they go read
a good aerodynamics text and not expect to find it in a couple of
paragraphs in a USENET posting.

--
Jim Pennino

Remove .spam.sux to reply.

Le Chaud Lapin

October 3rd 07, 05:35 PM

On Oct 3, 11:28 am, Bertie the Bunyip > wrote:
> "Kloudy via AviationKB.com" <u33403@uwe> wrote innews:79253d6018083@uwe:
>
> > Funny...I suspect you know what that looks like. ; )
>
> Nah,I just have a good imagination.
> Though if oyu send me some crack I do have some chickens I could try it on.
>
> Bertie

:))))!

-Le Chaud Lapin-

Le Chaud Lapin

October 3rd 07, 05:48 PM

On Oct 3, 10:34 am, wrote:
> On Oct 3, 8:15 am, Le Chaud Lapin > wrote:
>
> > Actually I did because every book I read about flying skimped on the
> > subject. I'm going to hop over to MIT's OpenCourseWare later this
> > week and download their most basic course on aero/astro. Benoulli's
> > principle is toss around as if it were facecloth, but I'm getting the
> > feeling that no one is really doing the physics.
>
> Lemme see: People have been building flying machines since the late
> 1800's, about 125 years now, and none of them have been interested
> enough in the phenomenon of lift to do the physics? How old are you,
> anyway? Many of the contributors here have been flying much longer
> than you have likely been alive and have studied this in detail, and
> some of them might even have doctorates in the subject. The subject of
> lift has been beaten to death on this forum and if you Googled it
> you'd find some good information.

I want to be clear. I did not me to say "no one" is doing the
physics. Obviously there are aero/astro scientists all over the
world. What I mean to say is that there seems to be a lot of *pilots*
who are using Bernoulli's principle somewhat carelessly, IMO. Some of
these people are CFI's. Please don't ask me to name individuals, but
I know with certainty that there are at least 2 living, breathing
CFI's who do not understand where 29.92 Hg comes from, or does not
understand it well enough to make it make sense to a student. The
might have understood it at one point, but they don't now. I know
because I asked them. My feelings about teaching is that if you are
not very certain about something, you do more damage than talking
about it. Of course, this leads to the conundrum of having to explain
to a student why a plane stays in the air without providing erroneous
information. If I were a CFI, I would simply say that the aerodynamics
result in pressure below plane is sufficient to counteract pressure
above planes for force of gravity. If they wanted to know more, I'd
direct them to book on aerodynamics.

Can you fly without understanding many of these things? Certainly.
But personally, I would feel a lot better in a cockpit if I did. The
more I know, the more confident I am, and if something goes wrong, the
added perspective will allow me to quickly eliminate those things
which I am certain is not root of problem. This reminds me of
incident about year ago when I was fixing a neighbor's car, and
another neighbor kindly ask me if we needed to borrow jumper cables,
even though she had heard the engine turn over with no problem many
times. Someone who understands how automobile works would have known
that it is highly unlikely that there was problem with battery with
such robust cranking. [Turned out to be fuel line].

-Le Chaud Lapin-

Mxsmanic

October 3rd 07, 05:56 PM

writes:

> Lemme see: People have been building flying machines since the late
> 1800's, about 125 years now, and none of them have been interested
> enough in the phenomenon of lift to do the physics?

The physics seems simpler than it is, and the explanation of the physics
depends hugely on one's frame of reference.

However, the practical reality is simple: an airfoil with an angle of attack
greater than zero and less than the critical (stall) angle will produce lift.
This is completely reliable, and it's all a pilot needs to know (although,
oddly enough, many pilots don't know this).

> Many of the contributors here have been flying much longer
> than you have likely been alive and have studied this in detail, and
> some of them might even have doctorates in the subject.

See above.

> We run into this attitude rather
> frequently in the flight training industry. It tends to make the
> student unteachable.

Students only need to know about the angle of attack, if theory is required.
Or you can simply teach them by rote, which is even easier albeit somewhat
less safe.

Le Chaud Lapin

October 3rd 07, 05:56 PM

Mxsmanic

October 3rd 07, 05:56 PM

Le Chaud Lapin writes:

> For example, as I mentioned earlier, I am reading Jeppesens Private
> Pilot manual, and there are clearly errors in concept the manual
> (energy being created by engine, for example), even though Jeppensen
> probably has access to as many Ph.D. laureates as they want.

Describe the errors in a letter and send it to them. Good technical
publishers are always willing to accept corrections.

Bertie the Bunyip[_19_]

October 3rd 07, 06:02 PM

Le Chaud Lapin > wrote in
oups.com:

> On Oct 3, 10:34 am, wrote:
>> On Oct 3, 8:15 am, Le Chaud Lapin > wrote:
>>
>> > Actually I did because every book I read about flying skimped on
the
>> > subject. I'm going to hop over to MIT's OpenCourseWare later this
>> > week and download their most basic course on aero/astro.
Benoulli's
>> > principle is toss around as if it were facecloth, but I'm getting
the
>> > feeling that no one is really doing the physics.
>>
>> Lemme see: People have been building flying machines since the late
>> 1800's, about 125 years now, and none of them have been interested
>> enough in the phenomenon of lift to do the physics? How old are you,
>> anyway? Many of the contributors here have been flying much longer
>> than you have likely been alive and have studied this in detail, and
>> some of them might even have doctorates in the subject. The subject
of
>> lift has been beaten to death on this forum and if you Googled it
>> you'd find some good information.
>
> I want to be clear. I did not me to say "no one" is doing the
> physics. Obviously there are aero/astro scientists all over the
> world. What I mean to say is that there seems to be a lot of *pilots*
> who are using Bernoulli's principle somewhat carelessly, IMO. Some of
> these people are CFI's. Please don't ask me to name individuals, but
> I know with certainty that there are at least 2 living, breathing
> CFI's who do not understand where 29.92 Hg comes from, or does not
> understand it well enough to make it make sense to a student. The
> might have understood it at one point, but they don't now. I know
> because I asked them. My feelings about teaching is that if you are
> not very certain about something, you do more damage than talking
> about it. Of course, this leads to the conundrum of having to explain
> to a student why a plane stays in the air without providing erroneous
> information. If I were a CFI, I would simply say that the aerodynamics
> result in pressure below plane is sufficient to counteract pressure
> above planes for force of gravity.

That's not enough either.

you need to know how and why lift varies throughot the flight envelope,
but after th ebook learning, it's mostly intuitive and the intuition
comes from experience.

Bertie

Bertie the Bunyip[_19_]

October 3rd 07, 06:03 PM

Mxsmanic > wrote in
:

> writes:
>
>> Lemme see: People have been building flying machines since the late
>> 1800's, about 125 years now, and none of them have been interested
>> enough in the phenomenon of lift to do the physics?
>
> The physics seems simpler than it is, and the explanation of the
> physics depends hugely on one's frame of reference.
>
> However, the practical reality is simple: an airfoil with an angle of
> attack greater than zero and less than the critical (stall) angle will
> produce lift. This is completely reliable, and it's all a pilot needs
> to know (although, oddly enough, many pilots don't know this).
>
>> Many of the contributors here have been flying much longer
>> than you have likely been alive and have studied this in detail, and
>> some of them might even have doctorates in the subject.
>
> See above.
>
>> We run into this attitude rather
>> frequently in the flight training industry. It tends to make the
>> student unteachable.
>
> Students only need to know about the angle of attack, if theory is
> required. Or you can simply teach them by rote, which is even easier
> albeit somewhat less safe.
>

You have no idea what you are talking about.

You don't fly and you never will, mercifully.

Bertie

Bertie the Bunyip[_19_]

October 3rd 07, 06:05 PM

Le Chaud Lapin > wrote in
ups.com:

> On Oct 3, 10:34 am, wrote:
>> Both Newton and Bernoulli are correct. Even inside a pipe the
>> static pressure drops as velocity increases. That's why your bottom
>> table jumps as you yank off the top one: you accelerated an airflow.
>> And in generating lift there's a displacement of air. Can't escape
>> that at all.
>
> Also, if you don't mind, I would like to understand what you mean
> here.
>
> It's not clear to me.
>

Couldn't be clearer and it's really all you need to know.

Go out and fly now. If you ask any more questions I'l just hand you over to
Anthony from now on.

Tough love.

Bertie

Le Chaud Lapin

October 3rd 07, 06:28 PM

On Oct 3, 12:05 pm, Bertie the Bunyip > wrote:
> Le Chaud Lapin > wrote roups.com:
>
> > On Oct 3, 10:34 am, wrote:
> >> Both Newton and Bernoulli are correct. Even inside a pipe the
> >> static pressure drops as velocity increases. That's why your bottom
> >> table jumps as you yank off the top one: you accelerated an airflow.
> >> And in generating lift there's a displacement of air. Can't escape
> >> that at all.
>
> > Also, if you don't mind, I would like to understand what you mean
> > here.
>
> > It's not clear to me.
>
> Couldn't be clearer and it's really all you need to know.
>
> Go out and fly now. If you ask any more questions I'l just hand you over to
> Anthony from now on.

I don't think actually flying an airplane will explain the
aerodynamics of lift any more than driving a car will help with
understanding of rack-and-pinion. Yes, there will be an an intuition
that will develop, but that's going to happen anyway, and that would
have happened even if I were a 16-year-old sitting in pilot's seat.
Doesn't mean that 16-year-old is going to understand aerodynamics.

Let's face it. A large pecentage of people walking this planet think
there is a "suction" force. I was watching the History Channel one
day, and the narrator actually used that term - a "suction" force, and
he did not mean the force that is on the other side of the barrier
where the "suction" force was being applied. I've also seen countless
erroneous explantions on the same channel about electronics which I do
know about. Typically the narrator will say voltage when he meant
current, or energy when he meant power.

I'm more of a mind-over-matter type. I'll get my license and fly
around and develop the intuition that you mention, certainly, but
that's not enough.

-Le Chaud Lapin-

Bertie the Bunyip[_19_]

October 3rd 07, 06:31 PM

Le Chaud Lapin > wrote in
ups.com:

> On Oct 3, 12:05 pm, Bertie the Bunyip > wrote:
>> Le Chaud Lapin > wrote
>> roups.com:
>>
>> > On Oct 3, 10:34 am, wrote:
>> >> Both Newton and Bernoulli are correct. Even inside a pipe
>> >> the
>> >> static pressure drops as velocity increases. That's why your
>> >> bottom table jumps as you yank off the top one: you accelerated an
>> >> airflow. And in generating lift there's a displacement of air.
>> >> Can't escape that at all.
>>
>> > Also, if you don't mind, I would like to understand what you mean
>> > here.
>>
>> > It's not clear to me.
>>
>> Couldn't be clearer and it's really all you need to know.
>>
>> Go out and fly now. If you ask any more questions I'l just hand you
>> over to Anthony from now on.
>
> I don't think actually flying an airplane will explain the
> aerodynamics of lift any more than driving a car will help with
> understanding of rack-and-pinion.

Well, then you're a lost cause.

Ask Anthony and be damned, then

Bertie

[email protected]

October 3rd 07, 07:33 PM

On Oct 3, 10:56 am, Le Chaud Lapin > wrote:
> On Oct 3, 10:34 am, wrote:
>
> > Both Newton and Bernoulli are correct. Even inside a pipe the
> > static pressure drops as velocity increases. That's why your bottom
> > table jumps as you yank off the top one: you accelerated an airflow.
> > And in generating lift there's a displacement of air. Can't escape
> > that at all.
>
> Also, if you don't mind, I would like to understand what you mean
> here.
>
> It's not clear to me.
>
> -Le Chaud Lapin-

See http://www.petester.com/html/bachap02.html or
Google yourself using terms like static, dynamic pressures, kinetic
energy, converging or diverging ducts, net energy, and so on. If we
have gas flow in a pipe, and if we had a static gauge and a dynamic
pressure gauge (airspeed), we would see the static pressure fall as
the airspeed rose. If the no-movement static pressure was 29.92" hg,
the dynamic pressure would be zero. As the speed comes up to, say,
10" hg on the dynamic, the static will fall 10" to 19.92. There is no
free lunch. The static and dynamic always add up to the same figure as
speed increases or decreases, unless there is further energy input as
in a turbine combustion section.
As I said, it's not intuitive. Converging and diverging ducts
do different things than you'd expect, but we know they work because
the turbine engine uses their principles, and wouldn't work without
them.

Dan

Le Chaud Lapin

October 3rd 07, 09:11 PM

On Oct 3, 1:33 pm, wrote:
> On Oct 3, 10:56 am, Le Chaud Lapin > wrote:
>
> > On Oct 3, 10:34 am, wrote:
>
> > > Both Newton and Bernoulli are correct. Even inside a pipe the
> > > static pressure drops as velocity increases. That's why your bottom
> > > table jumps as you yank off the top one: you accelerated an airflow.
> > > And in generating lift there's a displacement of air. Can't escape
> > > that at all.
>
> > Also, if you don't mind, I would like to understand what you mean
> > here.
>
> > It's not clear to me.

[explanation of Bernoulli's principle clipped].

I did not mean that I did not understand Bernoulli's principle.

What I am saying is that I do not believe that the bottom table jumps
because of airflow acceleration. In fact, if I were to use tables
with circular faces, and put the entire apparatus in a giant
cylindrical tube, and pull up on the top table, assuming that the very
bottom of the tube were open-ended, the bottom table would follow the
top table upward, no matter how fast any air inside the tube were
moving. I could move the top table one molecular diameter every
10,000,000 years, and after the top table has moved, say, 0.5 meters,
the bottom table will follow. This assumes, of course, that the
appartus is airtight, that no air from outside the tube can squeeze in
between the walls of table and tube to fill the void that was created.

There are 14.7 lbs per square inch of pressure pressing upward against
the underside of the bottom table. The yanking of the top table
creates a vacuum between the two faces of the table. The lack of
pressure on the top of the bottom table leaves nothing to counteract
the pressure pressing upward on the underside of the bottom table.
Then the only thing holding the bottom table on the floor is gravity.
Assuming that the table is a typical table of typical weight and size,
one is guranteed that the impulse net pressure of 14.7lbs / in^2 is
enough to overcome gravity and lift the bottom table off the floor.

Note that this really has nothing to do with Bernoulli's principle or
dynamic pressures.

If it is still not clear, put the assembly in a tube again, anchor the
bottom table with a tie wire so it cannot move upward, and using a
hydraulic jack, pull the top table upward, then stop, wait a minute,
have a Coke (sipping with a straw of course), then take cutters and
snap the wire holding the bottom table to the floor.

At the precise moment that the wire is snapped, there is no movement
of anthing at all. There is no Bernoulli action.

The bottom table will rush up toward the top table, even slamming
against it quite hard if the coefficient of sliding friction between
table-side and tube wall is low enough.

-Le Chaud Lapin-

Morgans[_2_]

October 3rd 07, 09:20 PM

"Le Chaud Lapin" <> wrote in message

> I'm saying that, if you take a plane with certain critical angle,
> throw away engine, put on an engine that can generate 10x the thrust,
> the plane should still fly, even if you exceed critical angle.
>
> These books imply that the critical angle is angle at with bad things
> happen above the wing, and because of that, the plane will fall. I'm
> saying that, you can have all the bad things happen above the wing and
> still be able to keep the plane aloft due to compression that occurs
> beneath the wing.
>
> Of course, I have only been doing this officially 7 weeks, so I might
> be wrong. ;)

You are.

With a stronger engine, the wing would still be stalled. You would be
flying on the thrust of the engine.

Disruption of the flow on the top side of the wing is what defines a stall.
The wing would create only a fraction of the list that it would, unstalled.
--
Jim in NC

Just go look it up!

October 3rd 07, 09:43 PM

On Tue, 02 Oct 2007 20:33:46 -0700, george > wrote:

>On Oct 3, 1:57 pm, Le Chaud Lapin > wrote:
>
>> "In addition to the lowered pressure, a downward-backward flow of air
>> also is generated from the top surface of the wing. The reaction to
>> this downwash results in an upward force on the wing which demnstrates
>> Newtons' third law of motion. This action/reaction principle also is
>> apparent as the airstream strikes the lwoer surface of the wing when
>> inclinded at a small angle (the angle of attack) to its direction of
>> motion. The air is forced downward and therefore causes an upward
>> reaction resulting in positive lift."
>
>
>I blame the lift pixies myself

I thought it was how the airflow goes through the splaps?

Kloudy via AviationKB.com

October 3rd 07, 09:49 PM

Bertie the Bunyip wrote:
>Though if oyu send me some crack I do have some chickens I could try it on.
>
>Bertie

Chicken you have, eh?

I want to be clear. I did not me to say "no one" is doing the
physics. Obviously there are chickens all over the
world. What I mean to say is that there seems to be a lot of farm fowl
who are using Bernoulli's principle somewhat carelessly, IMO. Some of
these roasters are CFI's (Chicken Food Items). Please don't ask me to name
individuals (Rhode Island Reds, Faverolles) but I know with certainty that
there are at least 2 living, breathing
guinea hens who do not understand where 29.92 Hg comes from, or does not
understand it well enough to make it make sense to other livestock. They
might have understood it at one point, but they don't now. I know
because I asked them and ate them.
My feelings about teaching is that if you are
not very certain about something, you do more damage than talking
about it. Of course, this leads to the conundrum of having to explain
to chickens why a sparrow stays in the air without providing erroneous
information. If I were a delicious farm fowl, I would simply say that the
marinade's
result in pressure below skin is sufficient to counteract pressure
above breast meat for force of gravity.
If they wanted to know more, I'd direct them to book on preparing delicious
poultry.

I don't think actually roasting a bird will explain the thermodynamic
contraction of proteins any more than braising a cow will help with
understanding of BBQ rack of ribs. Yes, there will be an an intuition
that will develop, but that's going to happen anyway, and that would
have happened even if I were a 16-year-old sitting in a restaurant.
Doesn't mean that 16-year-old is going to understand food science.

Let's face it. A large pecentage of people walking this planet think
there is a "poultry" force. I was watching the History Channel one
day, and the narrator actually used that term - a "poultry" force, and
he did not mean the force that is on the other side of the grill
where the "poultry" force was being applied. I've also seen countless
erroneous explantions on the same channel about bovine slaughter methods,
which I do
know about. Typically the narrator will say captured bolt when he meant
head-whacker, or ZAPPO! when he meant lethal humane execution.

I'm more of a mind-over-muncher type. I'll get my bib on and nibble
around and develop the intuition that you mention, certainly, but
that's not enough.

sorry, this all was seeming a bit tedious to me.

--
Message posted via http://www.aviationkb.com

Le Chaud Lapin

October 3rd 07, 10:09 PM

On Oct 3, 3:49 pm, "Kloudy via AviationKB.com" <u33403@uwe> wrote:
>
> sorry, this all was seeming a bit tedious to me.

ROFL!!!!

-Le Chaud Lapin-

Bertie the Bunyip

October 3rd 07, 10:12 PM

On 3 Oct, 17:56, Mxsmanic > wrote:
> Le Chaud Lapin writes:
> > For example, as I mentioned earlier, I am reading Jeppesens Private
> > Pilot manual, and there are clearly errors in concept the manual
> > (energy being created by engine, for example), even though Jeppensen
> > probably has access to as many Ph.D. laureates as they want.
>
> Describe the errors in a letter and send it to them. Good technical
> publishers are always willing to accept corrections.

Thus the pile of "thank you for your input" letters.

Froootloop.

Bertie

Bertie the Bunyip

October 3rd 07, 10:14 PM

On 3 Oct, 21:11, Le Chaud Lapin > wrote:
> On Oct 3, 1:33 pm, wrote:
>
> > On Oct 3, 10:56 am, Le Chaud Lapin > wrote:
>
> > > On Oct 3, 10:34 am, wrote:
>
> > > > Both Newton and Bernoulli are correct. Even inside a pipe the
> > > > static pressure drops as velocity increases. That's why your bottom
> > > > table jumps as you yank off the top one: you accelerated an airflow.
> > > > And in generating lift there's a displacement of air. Can't escape
> > > > that at all.
>
> > > Also, if you don't mind, I would like to understand what you mean
> > > here.
>
> > > It's not clear to me.
>
> [explanation of Bernoulli's principle clipped].
>
> I did not mean that I did not understand Bernoulli's principle.
>
> What I am saying is that I do not believe that the bottom table jumps
> because of airflow acceleration. In fact, if I were to use tables
> with circular faces, and put the entire apparatus in a giant
> cylindrical tube, and pull up on the top table, assuming that the very
> bottom of the tube were open-ended, the bottom table would follow the
> top table upward, no matter how fast any air inside the tube were
> moving. I could move the top table one molecular diameter every
> 10,000,000 years, and after the top table has moved, say, 0.5 meters,
> the bottom table will follow. This assumes, of course, that the
> appartus is airtight, that no air from outside the tube can squeeze in
> between the walls of table and tube to fill the void that was created.
>
> There are 14.7 lbs per square inch of pressure pressing upward against
> the underside of the bottom table. The yanking of the top table
> creates a vacuum between the two faces of the table. The lack of
> pressure on the top of the bottom table leaves nothing to counteract
> the pressure pressing upward on the underside of the bottom table.
> Then the only thing holding the bottom table on the floor is gravity.
> Assuming that the table is a typical table of typical weight and size,
> one is guranteed that the impulse net pressure of 14.7lbs / in^2 is
> enough to overcome gravity and lift the bottom table off the floor.
>
> Note that this really has nothing to do with Bernoulli's principle or
> dynamic pressures.
>
> If it is still not clear, put the assembly in a tube again, anchor the
> bottom table with a tie wire so it cannot move upward, and using a
> hydraulic jack, pull the top table upward, then stop, wait a minute,
> have a Coke (sipping with a straw of course), then take cutters and
> snap the wire holding the bottom table to the floor.
>
> At the precise moment that the wire is snapped, there is no movement
> of anthing at all. There is no Bernoulli action.
>
> The bottom table will rush up toward the top table, even slamming
> against it quite hard if the coefficient of sliding friction between
> table-side and tube wall is low enough.
>

Whoowh!
Zero point energy!

In my own kitchen!

I can tell the electric company to **** off now.

Bertie

Bertie the Bunyip

October 3rd 07, 10:15 PM

On 3 Oct, 22:09, Le Chaud Lapin > wrote:
> On Oct 3, 3:49 pm, "Kloudy via AviationKB.com" <u33403@uwe> wrote:
>
>
>
> > sorry, this all was seeming a bit tedious to me.
>
> ROFL!!!!
>
> -Le Chaud Lapin-

Ah, a cluelessness vaguely remiscent of someone else I may have seen
around here.

Bertie

Morgans[_2_]

October 3rd 07, 10:26 PM

"Bertie the Bunyip" > wrote
>
> He's an idiot, what else does one need to know?

And yet so many can not resist posting replies to his posts, either with
corrections or witty zingers.

I'm starting to think that they are the bigger losers.

What we have lost is a good newsgroup. Why can't everyone see that when
they reply, he wins. And wins and wins.....

Folks, I'll say it _again_.

The ONLY way to get rid of a know-nothing, know-it-all, obnoxious troll, is
to IGNORE him. ALL of him. EVERY time, not just when you feel like it.

I thought we were turning a corner a couple days ago, with very few replies
to him being posted. Guess again.

Sigh.
--
Jim in NC

John Godwin

October 3rd 07, 10:26 PM

Bertie the Bunyip > wrote in
ups.com:

> Ah, a cluelessness vaguely remiscent of someone else I may have seen
> around here.
>
> Bertie

I wonder if Mx is really Bobo in sheep's clothing.

--

Morgans[_2_]

October 3rd 07, 10:31 PM

>> It is clearly time to revisit airplanes taking off on tredmills.

I have to agree. ANYTHING would be better than hearing the resident idiot
troll's blithering.

It goes something like this.

An airplane is about to takeoff on a runway, that is really a treadmill; a
very expensive treadmill.

The treadmill senses the airplane's speed, and matches the aircraft's speed,
with speed increases of its own.

Can the airplane takeoff? Why or why not?
--
Jim in NC

Mxsmanic

October 3rd 07, 10:33 PM

Le Chaud Lapin writes:

> Also, if you don't mind, I would like to understand what you mean
> here.

You can only push the wing upward if something else is pushed downward. Thus,
the wing generates lift only to the extent that it diverts a substantial mass
(of air) downward. No downwash, no lift.

Bertie the Bunyip

October 3rd 07, 10:37 PM

On 3 Oct, 13:27, "BDS" > wrote:
> "Mxsmanic" > wrote
>
> > Le Chaud Lapin writes:
>
> > > What is the definition of a stall anyway?
>
> > An abrupt loss of lift.
>
> Son, for someone who continually chastises the pilots here for their lack of
> knowledge, you sure can come up with some doozies yourself!
>

Actually, it's correct, but only because he read it off wickepedia or
something.

It's not like he'd actually ever DO a stall.

Bertie

Bertie the Bunyip

October 3rd 07, 10:37 PM

On 3 Oct, 05:54, Mxsmanic > wrote:
> Dan Luke writes:
> > Then why does the wing stall and cease lifting when flow separates from the
> > upper surface?
>
> Because it is no longer accelerating air efficiently downward.

Wrong again, fjukktard.

Bertei

Bertie the Bunyip

October 3rd 07, 10:39 PM

On 3 Oct, 22:33, Mxsmanic > wrote:
> Le Chaud Lapin writes:
> > Also, if you don't mind, I would like to understand what you mean
> > here.
>
> You can only push the wing upward if something else is pushed downward. Thus,
> the wing generates lift only to the extent that it diverts a substantial mass
> (of air) downward. No downwash, no lift.

Nope.

Wrong again, fjukkwit.

Of course, it doesn't matter sionc eyou will never fly and your
sockpuppet there won't either.

Bertie

Morgans[_2_]

October 3rd 07, 10:41 PM

<jimp wrote

> I think the main issue is that it doesn't require a Phd in physics to
> fly an airplane and the explanations of lift, stall, drag, etc.
> for pilots tend to be highly simplified, and rightfully so.
>
> A full explanation that would satisfy a physisicist would likely
> cause exterme eye glaze in the average pilot.
>
> If one want's that level of insight, I would suggest they go read
> a good aerodynamics text and not expect to find it in a couple of
> paragraphs in a USENET posting.

Exactly.

To learn to fly, it is important to understand aerodynamics to the point of
knowing what you can do to mess them up, and what you can do to fix things.
Only the most basic understanding of the subject is needed to achieve these
goals.
--
Jim in NC

Bertie the Bunyip

October 3rd 07, 10:45 PM

On 3 Oct, 22:26, John Godwin > wrote:
> Bertie the Bunyip > wrote roups.com:
>
> > Ah, a cluelessness vaguely remiscent of someone else I may have seen
> > around here.
>
> > Bertie
>
> I wonder if Mx is really Bobo in sheep's clothing.
>

Nah. just as k00ky, different style.

Anthony needs something a little different from Bobo and Bertie will
provide..

BTW, if you feel the urge to harass bobo, you can still find him in
alt.security .alar,s, where he still causes just as much trouble as he
ever did. I pop in and pull his chain every once in a while.

Bertie

Bertie

Le Chaud Lapin

October 3rd 07, 11:04 PM

On Oct 3, 4:14 pm, Bertie the Bunyip >
wrote:
> Whoowh!
> Zero point energy!
>

Surely, you must be joking. The exposition I wrote above is nothing
more than high school physics.

Where do you see me implying zero point energy?

I know my physics. Do you? There is no "zero point" energy.

Plain and simple:

If a person sucks on a straw, the reason the fluid rises has *NOTHING*
to do with Bernoull's principle. It has to do with the balance in
force being eliminated. In particular, the air in the straw is
removed, so the 14.4lbs/square in will lift the fluid in the straw.

This should be familiar to you, since you are a pilot. Where do you
think 29.92 Hg comes from? It comes from the height that a column of
mercury will rise in a complete rarefied tube in STP, which just
happens to be 29.92.

Both you and Mxmanic are wrong.

-Le Chaud Lapin-

Kloudy via AviationKB.com

October 3rd 07, 11:25 PM

Le Chaud Lapin wrote:
>
>Both you and Mxmanic are wrong.
>
>-Le Chaud Lapin-

ooooo.....wait for it.....here it comes....

--
Message posted via http://www.aviationkb.com

[email protected]

October 3rd 07, 11:56 PM

On Oct 3, 4:04 pm, Le Chaud Lapin > wrote:

> If a person sucks on a straw, the reason the fluid rises has *NOTHING*
> to do with Bernoull's principle. It has to do with the balance in
> force being eliminated. In particular, the air in the straw is
> removed, so the 14.4lbs/square in will lift the fluid in the straw.

So, if it has nothing to do with Bernoulli, what has it to do
with lift? With tables and straws and the like we're talking static,
not dynamic pressures. The airplane uses dynamic AND static
pressures.
In cruise flight (low AOA), I would expect a reduced pressure
on the bottom of the wing, though not as low as on the top. The
velocity of air across the bottom will drop its pressure, there, too.
Air has mass. Anytime you try to push it out of the way,
there will be some reaction. Newton says so. We know this as drag.
But we also know it as lift reaction. A flat plate flying
through the air at some tiny angle of attack doesn't have much faster
air over the top than the bottom, if any difference at all, yet it
will generate plenty of lift. Try this on, if you want to think
outside the box: The airfoil we know is just that: a foil (device to
deceive) to trick the air into flowing over it without breaking up at
much higher angles of attack than a flat plate would let us. So the
leading edge has to have some radius so the air can get around the
corner from the natural stagnation point under the LE at high AOA, and
that curve must gradually taper off toward the rear or the now-
disturbed air would want to separate and turbulate, and if it did that
it would then slow down dramatically, pressure would rise and lift
would decrease. But, happily, Newton is still at work underneath so
the airplane falls, but not as if the wings fell off. We're still
moving forward and the wing is still shoving air out of the way
downward, so lift is still generated.

Dan

Morgans[_2_]

October 4th 07, 12:33 AM

"Morgans" <> wrote
>
> It goes something like this.
>
> An airplane is about to takeoff on a runway, that is really a treadmill; a
> very expensive treadmill.
>
> The treadmill senses the airplane's speed, and matches the aircraft's
> speed, with speed increases of its own.
>
> Can the airplane takeoff? Why or why not?

I forgot one important qualifier of the treadmill's operation.

It goes in the opposite direction of the intended direction of travel for
the airplane.
--
Jim in NC

Le Chaud Lapin

October 4th 07, 12:40 AM

On Oct 3, 5:56 pm, wrote:
> So, if it has nothing to do with Bernoulli, what has it to do
> with lift?

You can have lift of an object with no Bernoulli. It's simple vector
addition.

> With tables and straws and the like we're talking static,
> not dynamic pressures. The airplane uses dynamic AND static
> pressures.

Right.

> In cruise flight (low AOA), I would expect a reduced pressure
> on the bottom of the wing, though not as low as on the top. The
> velocity of air across the bottom will drop its pressure, there, too.

Right. The AOA matters here. Angle the wing up any significant amount,
and over-pressure will build under the wing.

> Air has mass. Anytime you try to push it out of the way,
> there will be some reaction. Newton says so. We know this as drag.

Hmm...ok, sure. I wouldn't call that drag necessarily. That's like
saying that a hydraulic piston assembly has drag. I more prefer to
think of drag as laminar fricitional forces of the fluid. Pushing out
of way implies that plane doing the pushing is perpendicular to the
direction in which pushing is being done (which is true at leading
edge of wing). But I guess this is acceptable.

> But we also know it as lift reaction. A flat plate flying
> through the air at some tiny angle of attack doesn't have much faster
> air over the top than the bottom, if any difference at all, yet it
> will generate plenty of lift. Try this on, if you want to think
> outside the box:

Thinking outside the box is what lead me to refuse to accept hand-
waving explanations of aerodynamics from CFI's.

> The airfoil we know is just that: a foil (device to
> deceive) to trick the air into flowing over it without breaking up at
> much higher angles of attack than a flat plate would let us. So the
> leading edge has to have some radius so the air can get around the
> corner from the natural stagnation point under the LE at high AOA, and
> that curve must gradually taper off toward the rear or the now-
> disturbed air would want to separate and turbulate, and if it did that
> it would then slow down dramatically, pressure would rise and lift
> would decrease. But, happily, Newton is still at work underneath so
> the airplane falls, but not as if the wings fell off. We're still
> moving forward and the wing is still shoving air out of the way
> downward, so lift is still generated.

Yes this is true, but the explanation in the Jeppensen book is wrong.
it defines downwash:

downwash: - "the downward deflection of the airstream as it passes
over the wing and past the trailing edge"

It goes on to say:

"According to Bernoulli's principle, the increase in speed of air on
top of an airfoil profdues a drop in pressure and this lowered
pressure is a component of lift."

Ok, we really know that the lift results from what's under the wing no
longer being balanced out, but I won't nit-pick this explanation.

Next paragraph it says:

"In addtion to the lowered pressure, a downwar-backward flow of air is
also generated from the top surface of the wing. The reaction to this
downwash results in an upward force on the wing which demnstrates
Newton's third law of motion."

This is plane false. That is *NOT* what Newton said. Newton did not
say you could take any action and willy-nilly find what you think is
the reaction, and say, "Hey, this looks good, let's use this."

Newtons law, in fact, is better stated as reciprocity of force, IMO.
This says that, if you take two objects, one apply force to the other,
the other, by reciprocity, must appy an opposite force against the
first.

Newton's law, conbine with F=ma, also yields the notion of
conservation of momentum.

But getting back to Jeppensen, the downwash, if they mean what's
happening on the top surface of the wing, is *not* contributing to
lift. Note that they say "results in", but don't explain how. This
seems to be typical of books of flight dynamics.

I'd like to point something else out regarding Bernouilli's principle.

I haven't tried, but I suspect that I could build a contraption that
consists of surface where the velocity of air above the surface is
much higher than that below, but the pressure above the surface is
higher.

-Le Chaud Lapin-

Crash Lander[_1_]

October 4th 07, 12:50 AM

"Dudley Henriques" > wrote in message
...
> Tina wrote:
>> Then there's the Mx medical advice column, physics advice -- I'm
>> waiting for a unified field theory, or maybe a proposed standard of
>> care for depression.
>>
>> I had a thought for what would be the longest thread ever in this
>> newsgroup -- "The collected corrections of Mx statements". Bertie
>> could be its editor, he has a deft and gentle way of pointing out
>> errors.
>>
>>
>
> I love Bertie's personal rendition of Occam's Razor to Anthony's long
> extended posts where he "explains" everything in intimate and minute
> detail.
>
> "Nope"!
>
>
> --
> Dudley Henriques

I'd like to see what his thoughts are on String Theory.
LOL.
Crash Lander

--
Straight and Level Down Under.
http://www.straightandleveldownunder.net/

Dudley Henriques[_2_]

October 4th 07, 12:55 AM

Crash Lander wrote:
> "Dudley Henriques" > wrote in message
> ...
>> Tina wrote:
>>> Then there's the Mx medical advice column, physics advice -- I'm
>>> waiting for a unified field theory, or maybe a proposed standard of
>>> care for depression.
>>>
>>> I had a thought for what would be the longest thread ever in this
>>> newsgroup -- "The collected corrections of Mx statements". Bertie
>>> could be its editor, he has a deft and gentle way of pointing out
>>> errors.
>>>
>>>
>> I love Bertie's personal rendition of Occam's Razor to Anthony's long
>> extended posts where he "explains" everything in intimate and minute
>> detail.
>>
>> "Nope"!
>>
>>
>> --
>> Dudley Henriques
>
> I'd like to see what his thoughts are on String Theory.
> LOL.
> Crash Lander
>

I'm sure he'd most likely say that twine was better :-))

--
Dudley Henriques

Le Chaud Lapin

October 4th 07, 12:58 AM

On Oct 3, 6:33 pm, "Morgans" > wrote:
> > It goes something like this.
>
> > An airplane is about to takeoff on a runway, that is really a treadmill; a
> > very expensive treadmill.
>
> > The treadmill senses the airplane's speed, and matches the aircraft's
> > speed, with speed increases of its own.
>
> > Can the airplane takeoff? Why or why not?
>
> I forgot one important qualifier of the treadmill's operation.
>
> It goes in the opposite direction of the intended direction of travel for
> the airplane.

Tricky question. I will take a stab at it.

You said "sense the airplanes speed". Relative to what?

Assuming no friction between wheels and treadmill, the prop of the
plane will cause the airplane to move in the wind. The speed
"sensing" of the airplane by the treadmill does not really make sense
and less you mean that the treadmill senses relative to the wind.

If the treadmill senses that the plane has a relative wind speed of
Vpw, and starts moving in the opposite direction, and the relative
speed of wind against treadwill were nil before all this started, then
the treadmill will only cause the wheels to turn twice as fast as they
would have if the treadmill had not been moving. In this case, the
speed of the plane relative to the treadmill will simply be twice the
speed of the plane relative to the win, in opposite direction, of
course. The plane will take off.

If you mean to imply that there is some way for the treadmill to sense
the speed of the plane relative to the treadmill, then adjust the
speed of treadmill accordingly, of course, that won't work, as it is a
circuitous proposition.

-Le Chaud Lapin-

BDS

October 4th 07, 01:09 AM

"Bertie the Bunyip" >...
> On 3 Oct, 13:27, "BDS" > wrote:
> > "Mxsmanic" > wrote
> >
> > > Le Chaud Lapin writes:
> >
> > > > What is the definition of a stall anyway?
> >
> > > An abrupt loss of lift.
> >
> > Son, for someone who continually chastises the pilots here for their
lack of
> > knowledge, you sure can come up with some doozies yourself!
> >
>
> Actually, it's correct, but only because he read it off wickepedia or
> something.

Here's my take on it - a stall occurs at the angle of attack where the
coefficient of lift stops increasing with angle of attack and begins to
decrease. It continues to decrease beyond this point as angle of attack is
increased further. It is not necessarily an abrupt change - most lift
versus angle of attack curves that I've seen do not have a drastic (abrupt)
drop beyond the peak.

BDS

Bertie the Bunyip

October 4th 07, 01:25 AM

BDS wrote:
> "Bertie the Bunyip" >...
> > On 3 Oct, 13:27, "BDS" > wrote:
> > > "Mxsmanic" > wrote
> > >
> > > > Le Chaud Lapin writes:
> > >
> > > > > What is the definition of a stall anyway?
> > >
> > > > An abrupt loss of lift.
> > >
> > > Son, for someone who continually chastises the pilots here for their
> lack of
> > > knowledge, you sure can come up with some doozies yourself!
> > >
> >
> > Actually, it's correct, but only because he read it off wickepedia or
> > something.
>
> Here's my take on it - a stall occurs at the angle of attack where the
> coefficient of lift stops increasing with angle of attack and begins to
> decrease. It continues to decrease beyond this point as angle of attack is
> increased further. It is not necessarily an abrupt change - most lift
> versus angle of attack curves that I've seen do not have a drastic (abrupt)
> drop beyond the peak.

Yes, sorry, you´re right and that´s more accurate. i mistakenly
assumed that you were adfvocating the buffet definition.

Bertie

Bertie the Bunyip

October 4th 07, 01:27 AM

Le Chaud Lapin wrote:
> On Oct 3, 4:14 pm, Bertie the Bunyip >
> wrote:
> > Whoowh!
> > Zero point energy!
> >
>
> Surely, you must be joking. The exposition I wrote above is nothing
> more than high school physics.
>
> Where do you see me implying zero point energy?
>
> I know my physics. Do you? There is no "zero point" energy.

Actually, there is. Not theory anymore, proven in a lab..

You´re proving to be quite the plaything.

>
> Plain and simple:
>
> If a person sucks on a straw, the reason the fluid rises has *NOTHING*
> to do with Bernoull's principle. It has to do with the balance in
> force being eliminated. In particular, the air in the straw is
> removed, so the 14.4lbs/square in will lift the fluid in the straw.
>
> This should be familiar to you, since you are a pilot. Where do you
> think 29.92 Hg comes from? It comes from the height that a column of
> mercury will rise in a complete rarefied tube in STP, which just
> happens to be 29.92.
>
> Both you and Mxmanic are wrong.
>

Maybe, but I can fly.

Bertie

Bertie the Bunyip

October 4th 07, 01:28 AM

Morgans wrote:
> "Bertie the Bunyip" > wrote
> >
> > He's an idiot, what else does one need to know?
>
> And yet so many can not resist posting replies to his posts, either with
> corrections or witty zingers.
>
> I'm starting to think that they are the bigger losers.
>
> What we have lost is a good newsgroup. Why can't everyone see that when
> they reply, he wins. And wins and wins.....
>
> Folks, I'll say it _again_.
>
> The ONLY way to get rid of a know-nothing, know-it-all, obnoxious troll, is
> to IGNORE him. ALL of him. EVERY time, not just when you feel like it.
>
> I thought we were turning a corner a couple days ago, with very few replies
> to him being posted. Guess again.

It´s the main reason I´m here.

Bertie

Tina

October 4th 07, 01:29 AM

In fact, if there is a downward component of the air's velocity that
had come from its passage over the upper surface of the airfoil, then
there had been an acceleration provided to that air -- acceleration in
this case being conventionally defined as the second time derivative
of position.

Now, if the air is accelerated downward, and it has mass, it means
there had been a force applied. The local prime mover is of course the
wing, so it must experience an upward force. Maybe you have a
different idea as to on what that equal and opposite force is
operating on -- I'd be interested in hearing about that.

There are a number of basic principles in operation here, be careful
not to paint yourself into too tight a corner unless you are quite
expert.

I am not claiming skill in this area -- physics was a minor a long
time ago -- but I remember some of the basics.

Bertie the Bunyip

October 4th 07, 01:29 AM

Bertie the Bunyip

October 4th 07, 01:33 AM

Dudley Henriques[_2_]

October 4th 07, 01:39 AM

Tina wrote:
> In fact, if there is a downward component of the air's velocity that
> had come from its passage over the upper surface of the airfoil, then
> there had been an acceleration provided to that air -- acceleration in
> this case being conventionally defined as the second time derivative
> of position.
>
> Now, if the air is accelerated downward, and it has mass, it means
> there had been a force applied. The local prime mover is of course the
> wing, so it must experience an upward force. Maybe you have a
> different idea as to on what that equal and opposite force is
> operating on -- I'd be interested in hearing about that.
>
> There are a number of basic principles in operation here, be careful
> not to paint yourself into too tight a corner unless you are quite
> expert.
>
> I am not claiming skill in this area -- physics was a minor a long
> time ago -- but I remember some of the basics.
>

The main thing about all this is that both Bernoulli and Newton are
complete explanations of lift and will stand alone. In fact they are
both explanations of the same thing really as they occur simultainously
as lift is being created.
The big rub about Bernoulli is that for years Ole' Daniel was raped by
text books stating several totally false applications of Bernoulli as
fact. The equal transit theory for example, often stated as an
explanation for Bernoulli is totally incorrect.
The real truth of it is that neither Newton or Bernoulli were dealing
with lift at all in their respective work that explains lift.
My fondest hope is that someday, pilots will collectively get it
together enough to realize that Bernoulli and Newton are not in
competition with each other and never have been.
Personally though.....I like my old friend Mary Shafer's explanation for
lift that blames it on the "lift demons". :-)
DH

--
Dudley Henriques

Dudley Henriques[_2_]

October 4th 07, 01:43 AM

BDS wrote:
> "Bertie the Bunyip" >...
>> On 3 Oct, 13:27, "BDS" > wrote:
>>> "Mxsmanic" > wrote
>>>
>>>> Le Chaud Lapin writes:
>>>>> What is the definition of a stall anyway?
>>>> An abrupt loss of lift.
>>> Son, for someone who continually chastises the pilots here for their
> lack of
>>> knowledge, you sure can come up with some doozies yourself!
>>>
>> Actually, it's correct, but only because he read it off wickepedia or
>> something.
>
> Here's my take on it - a stall occurs at the angle of attack where the
> coefficient of lift stops increasing with angle of attack and begins to
> decrease. It continues to decrease beyond this point as angle of attack is
> increased further. It is not necessarily an abrupt change - most lift
> versus angle of attack curves that I've seen do not have a drastic (abrupt)
> drop beyond the peak.
>
> BDS
>
>

This is a good explanation.

--
Dudley Henriques

Tina

October 4th 07, 01:50 AM

Mr Dudley sir, those are not lift demons, those are lift fairies or
lift pixies. If you call them demons they may take you high and then
let go.

Newton warned us that for every fairy there is an equal and opposite
demon.

I would be interested in having the OP tell us how to derive
conservation of momentum from F=MA though.

Jim Logajan

October 4th 07, 01:58 AM

Dudley Henriques > wrote:
> Personally though.....I like my old friend Mary Shafer's explanation for
> lift that blames it on the "lift demons". :-)

No science like lift demons is ever the work of just one person. See for
example the collection titled:
"The Emerging Science of Lift Demons":

at this site:

http://www.main.org/polycosmos/glxywest/lift_faq.htm

Le Chaud Lapin

October 4th 07, 02:26 AM

On Oct 3, 7:29 pm, Tina > wrote:
> In fact, if there is a downward component of the air's velocity that
> had come from its passage over the upper surface of the airfoil, then
> there had been an acceleration provided to that air -- acceleration in
> this case being conventionally defined as the second time derivative
> of position.

The acceleration is indeed downward. If God declared that all air
molecules in the universe must remain still for the sake of USENET
explication, and the wing move forward, and you took a snapshot of
that picture, there would be a vacuum created above the wing. It would
be quite large (not laminar). The floor of this vacuum would be the
wing itself. The ceiling would be the underside of an air mass above
the entire wing, ready to move downward to fill the void. Now if God
said, "Let molecules move!", the air mass above would, indeed, push
downward. But they would not be allow to go completely downward.
Molecules accelerated from the leading edge of the wing would fly
backward, colliding with those coming from above, and the net-effect
would be a stream.

> Now, if the air is accelerated downward, and it has mass, it means
> there had been a force applied. The local prime mover is of course the
> wing, so it must experience an upward force. Maybe you have a
> different idea as to on what that equal and opposite force is
> operating on -- I'd be interested in hearing about that.

The force is coming from the air mass above the wing, the air mass
that would be right above the vacuum created if no molecules were
allowed to move. That airmass pushes downward, toward the void. This
has nothing to do with the wing, except that the wing created the
void, and also created high-pressure area at tip of wing causing
acceleration of air backwards.

> There are a number of basic principles in operation here, be careful
> not to paint yourself into too tight a corner unless you are quite
> expert.

> I am not claiming skill in this area -- physics was a minor a long
> time ago -- but I remember some of the basics.

I am not an expert either, but I know enough to know that the
explanations I am reading in books are, at best, misleading. Some of
them are plain wrong. Note: going to start a new thread so we can get
to the bottom of this.

And yes, I am certain. :)

-Le Chaud Lapin-

[email protected]

October 4th 07, 02:29 AM

On Oct 3, 6:39 pm, Dudley Henriques > wrote:

> The main thing about all this is that both Bernoulli and Newton are
> complete explanations of lift and will stand alone. In fact they are
> both explanations of the same thing really as they occur simultanously
> as lift is being created.
> The big rub about Bernoulli is that for years Ole' Daniel was raped by
> text books stating several totally false applications of Bernoulli as
> fact. The equal transit theory for example, often stated as an
> explanation for Bernoulli is totally incorrect.

Exactly. The equal-transit theory isn't correct. The air
over the top actually reaches the trailing edge *before* the bottom's
flow. Intuitive thinking would have it arriving later because the
distance is greater.
Our OP should see the diagrams here:
http://www.av8n.com/how/htm/airfoils.html

This one shows the pressure distribution over the typical cambered
airfoil:
http://www.kemi.fi/kk019065/calculators/ClarkY.jpg

Note that there's pressure acting on the bottom. Where would
that come from, if not Newton? And note that Bernoulli runs out of
steam on the top near the trailing edge, and the pressure actually
goes above ambient there. I see this on the wing of my Jodel in
flight. It's a low wing, fabric covered, and the pressures are easily
visible by the way the fabric is pressed down or pulled up between the
ribs. Over about the last third of the chord, the fabric is pushed
below the ribs as the pressure there goes quite positive, while ahead
of that it's pulled up.
Look at that leading edge. Lots of lift over the first bit,
right where we'd expect a lot of drag (positive pressure) instead.
Not at all what you'd expect intuitively, is it? And that's
where the uninformed get into trouble: by using "experience' gained
from other, vastly different things, or from reasoning based on
inadequate information.

After all the years of reading this stuff and seeing wind-
tunnel demos and graphs and all such, I know there's an awful lot of
information out there on the generation of lift. Most of it is
available on the 'net. The strangest thing is the newbie who starts to
argue with his textbooks, very publicly (as on a newsgroup) without
Googling it for himself first. He knows better, he's sure.

Dan

Dudley Henriques[_2_]

October 4th 07, 02:33 AM

Tina wrote:
> Mr Dudley sir, those are not lift demons, those are lift fairies or
> lift pixies. If you call them demons they may take you high and then
> let go.
>
> Newton warned us that for every fairy there is an equal and opposite
> demon.

Well.....as they say.....everything is relative; :-)))
I'm sitting here wondering if I could actually survive explaining
fairies and pixies at the bar at next reunion of the Naval Test Pilot
School :-))
With fighter pilots, you have to be REAL careful with the words you
throw out there, especially after a few rounds of "attitude adjustment".

Knew a guy once who got to his first fighter assignment and hadn't had
the honor of having a call sign given to him. To make an impression on
the squadron, on his first day of duty assignment he showed up at the
ready room with a tray full of the best damn muffins any of the guys had
ever tasted. His wife had baked them.
From that day on through his retirement, poor Ed was known as "Muffin".
Ya just have to pity a guy who flies formation with "Viper", "Ironman",
"and "Snake" with a callsign like "Muffin". He did get at least a
partial break. Most of the guys called him "Muff".
DH

--
Dudley Henriques

Tina

October 4th 07, 02:38 AM

"We" are not in need of getting to the bottom of this. Most of us have
been there and done that.This particular writer, if she chooses to
analyse physics problems, tends to use the Newtonion approximations as
first principles. The good news is my profession doesn't demand those
skills often. I would, however, be interested, as I mentioned earlier,
how you derive conservation of mV from Newton's force/acceleration
relationship. I think you made that claim earlier in this thread.

Dudley Henriques[_2_]

October 4th 07, 02:39 AM

Jim Logajan wrote:
> Dudley Henriques > wrote:
>> Personally though.....I like my old friend Mary Shafer's explanation for
>> lift that blames it on the "lift demons". :-)
>
> No science like lift demons is ever the work of just one person. See for
> example the collection titled:
> "The Emerging Science of Lift Demons":
>
> at this site:
>
> http://www.main.org/polycosmos/glxywest/lift_faq.htm
>

I remember the lift demon stories from years ago. In fact, I believe the
origins go back to WW2 in my memory anyway.
I just liked the Mary put it together. :-)

--
Dudley Henriques

TheSmokingGnu

October 4th 07, 03:22 AM

Morgans wrote:
> The ONLY way to get rid of a know-nothing, know-it-all, obnoxious troll, is
> to IGNORE him. ALL of him. EVERY time, not just when you feel like it.

Hush up and grab some popcorn with me n' Bertie. They're just announcing
the second act! :D

TheSmokingGnu

TheSmokingGnu

October 4th 07, 03:23 AM

Dudley Henriques wrote:
> Crash Lander wrote:
>> I'd like to see what his thoughts are on String Theory.
>> LOL.
>
> I'm sure he'd most likely say that twine was better :-))
>

What, and discount the obvious implications that Duct Tape has on modern
thinking?

TheSmokingGnu

Morgans[_2_]

October 4th 07, 03:25 AM

"Bertie the Bunyip" <> wrote

It´s the main reason I´m here.

Remind me again. What is the main reason you're here?

Why do you feel the need to answer his posts?
--
Jim in NC

TheSmokingGnu

October 4th 07, 03:26 AM

Le Chaud Lapin wrote:
> You can have lift of an object with no Bernoulli. It's simple vector
> addition.

1. You are talking about nature's abhorrence of a vacuum.
2. Vacuum abhorrence is not lift.
3. Airplanes do not generate lift as a result of vacuum abhorrence.
----------
Conclusion: you are not talking about how aircraft generate lift.

QED.

TheSmokingGnu

Dudley Henriques[_2_]

October 4th 07, 03:38 AM

TheSmokingGnu wrote:
> Dudley Henriques wrote:
>> Crash Lander wrote:
>>> I'd like to see what his thoughts are on String Theory.
>>> LOL.
> >
>> I'm sure he'd most likely say that twine was better :-))
>>
>
> What, and discount the obvious implications that Duct Tape has on modern
> thinking?
>
> TheSmokingGnu

Ah, duct tape!! Where would aviation be without it ?

--
Dudley Henriques

Le Chaud Lapin

October 4th 07, 03:46 AM

On Oct 3, 8:29 pm, wrote:
> After all the years of reading this stuff and seeing wind-
> tunnel demos and graphs and all such, I know there's an awful lot of
> information out there on the generation of lift. Most of it is
> available on the 'net. The strangest thing is the newbie who starts to
> argue with his textbooks, very publicly (as on a newsgroup) without
> Googling it for himself first. He knows better, he's sure.

What's strange is CFI'S (two of them) who did not know how to explain
VOR to an electrial engineer (me), who, after reading the discription
of how it works, could probably make after reading the technical
specs.

What's strange is one of the recognized leaders in flight training
materials using words like "energy" when they mean "power". I might
be a newbie to flying, but I'm not a newbie to physics.

-Le Chaud Lapin-

Le Chaud Lapin

October 4th 07, 03:50 AM

On Oct 3, 9:26 pm, TheSmokingGnu
> wrote:
> Le Chaud Lapin wrote:
> > You can have lift of an object with no Bernoulli. It's simple vector
> > addition.
>
> 1. You are talking about nature's abhorrence of a vacuum.
> 2. Vacuum abhorrence is not lift.
> 3. Airplanes do not generate lift as a result of vacuum abhorrence.
> ----------
> Conclusion: you are not talking about how aircraft generate lift.

Yes, I am. It's a combination of many things taking place at once.
Vacuum generation by the forward motion of the wing is one of them.

> QED.

-LCL-

Le Chaud Lapin

October 4th 07, 04:14 AM

On Oct 3, 8:38 pm, Tina > wrote:
> "We" are not in need of getting to the bottom of this. Most of us have
> been there and done that.This particular writer, if she chooses to
> analyse physics problems, tends to use the Newtonion approximations as
> first principles. The good news is my profession doesn't demand those
> skills often. I would, however, be interested, as I mentioned earlier,
> how you derive conservation of mV from Newton's force/acceleration
> relationship. I think you made that claim earlier in this thread.

Hmm...I was afraid you would say that.

A non-hand-waving explanation would too close to the quantum, and
so...it's a bit much to discuss, at least right now. I've posted more
messages in this thread in small period of time than I have ever for
any other topic, in the history of using USENET, or...as one might
say, dN/dt >> 0, where N is number of messages.

-Le Chaud Lapin-

TheSmokingGnu

October 4th 07, 04:26 AM

Le Chaud Lapin wrote:
> Yes, I am. It's a combination of many things taking place at once.
> Vacuum generation by the forward motion of the wing is one of them.

Then why do wings generate lift at negative AOA? Surely the immense
vacuum pressures generated would immediately pull any flying craft
desperately into the Earth the moment the wing crossed that threshold
(say, in a descent).

My goodness, it's a good thing you got on here to tell us all this;
imagine all those airliners going overhead that have been doing it wrong
all this time, actually descending to a destination. They ought very
well to know that they could never do such a thing because the vacuum
pressures won't allow it!

TheSmokingGnu

[email protected]

October 4th 07, 04:48 AM

On Oct 3, 9:26 pm, TheSmokingGnu
> wrote:
> Le Chaud Lapin wrote:
> > Yes, I am. It's a combination of many things taking place at once.
> > Vacuum generation by the forward motion of the wing is one of them.

And the other is the displacement of air downward.

> Then why do wings generate lift at negative AOA? Surely the immense
> vacuum pressures generated would immediately pull any flying craft
> desperately into the Earth the moment the wing crossed that threshold
> (say, in a descent).

Must be careful not to mix attitude up with angle of attack. The
path of the wing's chord line through the air determines AOA. If the
airplane is pointed downward a bit so that the chord line is down 2°
with respect to the horizon, and the descent path of the airplane is
3°, the AOA is still 1°. An airplane in a steep climb, with its nose
up 20°, does not have a 20° AOA. Its flight path is upward at maybe
10° so that its AOA is only 10°.

Some wings (thick, heavily cambered wings) will generate lift
at up to -4° AOA. The bottom surface of the wing is not the chord
line; that's the line between the leading and trailing edges. The
bottom surface might be angled downward even more in level flight. the
old Champ was a good example: the bottom surface was angled quite
visibly down in level cruise flight, but the chord line was still at a
positive degree or two.

Admittedly there are instructors who don't understand this
stuff well at all and think they know more than they do. I'm still
learning 34 years after starting to fly. I'm old enough now to realize
how little I knew when I thought I knew it all, and to know that I'll
now never have a good handle on it all. Too little time and too many
other responsibilities. But private pilots need to have the basics,
because that's all they have time for and because they'll kill
themselves without them. I'm appalled when I see a pilot do a low-and-
over and yank back hard for the vertical zoom. They have no idea how
close they come to an accelerated stall doing that. Those that manage
to get the stall don't live to avoid the same mistake again, and the
accident report gives a bland, uninteresting and uninformative "pilot
lost control in the climb after the low pass." They don't give the
real reason: the pilot did not understand AOA, never did, and thought
he was safe because the airplane's speed was well above the stall
speed.

Dan

Don Tuite

October 4th 07, 06:15 AM

It's curious. Nobody who's ever stood in the sllipstream of a
rotating propeller on a stationary plane says that a propeller merely
sucks an airplane through the sky. But people get into a tizzy if one
mentions Newton's third law wrt a wing. Bernoulli and Newton are not
alternatives; they are both universally and simultaneously the same
thing.

It's like those ladder-against-the- wall problems in Statics. The
forces don't change, but depending on what you're calculating,
sometimes you choose one reference point for your moments, sometimes
another.

Conservation of Energy: it's not just a good idea, it's the Law.

Don

Bertie the Bunyip[_19_]

October 4th 07, 06:24 AM

"Morgans" > wrote in news:XaYMi.122$uc1.57
@newsfe12.lga:

>
> "Bertie the Bunyip" <> wrote
>
> It´s the main reason I´m here.
>
> Remind me again. What is the main reason you're here?

I think I just told you.
>
> Why do you feel the need to answer his posts?

Sport

Bertie

Bertie the Bunyip[_19_]

October 4th 07, 06:26 AM

Dudley Henriques > wrote in
:

> TheSmokingGnu wrote:
>> Dudley Henriques wrote:
>>> Crash Lander wrote:
>>>> I'd like to see what his thoughts are on String Theory.
>>>> LOL.
>> >
>>> I'm sure he'd most likely say that twine was better :-))
>>>
>>
>> What, and discount the obvious implications that Duct Tape has on
>> modern thinking?
>>
>> TheSmokingGnu
>
> Ah, duct tape!! Where would aviation be without it ?
>

Absolutely. Or speed tape if you go a bit faster.

Bertie

Le Chaud Lapin

October 4th 07, 09:33 AM

On Oct 3, 10:48 pm, wrote:
> On Oct 3, 9:26 pm, TheSmokingGnu
>
> > wrote:
> > Le Chaud Lapin wrote:
> > > Yes, I am. It's a combination of many things taking place at once.
> > > Vacuum generation by the forward motion of the wing is one of them.
>
> And the other is the displacement of air downward.

By the bottom part of the wing, right? :D

Remember, when Newton was talking about the whole action/reaction
thing, he did not say you could arbitrarily define the sources of
forces. He was talking specifically about two objects, A and B, A
generating a force on B, and B generating a reciprocal force on A.

If you have compression under a wing do to extended flaps and laminar
friction of airflow, for example, then the lower surface of the wing
forces air downward, and the air beneath the lower surface forces wing
upward.

If you have have downwash above the wing, the downwash has to be due
to a force acting to move the air downward. I've argued that it is
effectively normal atmospheric pressure, acting against what
effectively becomes a partial vacuum generated by the forward
displacement of the wing, above the wing. Newton did not say that you
could arbitarily say, "Oh, there is some air moving downward, I'll
just pick a convenient reason arbitrarily."

Another way to look at this is to imagine a "level" wing with heavy
flap extension. Have an "air gorilla" move the entire wing forward, in
an abrupt motion, not given air anytime to redistributed. If this is
done, there will be compression beneath the wing, strong at the
boundary of compression, or in the flap pocket. Behind the win (above
it, but behind flaps), there will be ....

a huge void!

Now, if air is suddenly allowed to flow, yes indeed, there would be
downwash above the wing into the void, but the wing itself will not be
causing this downwash. It will be the pressure surrounding the void
causing the downwash. Since the source of movement of this air is not
the wing but the air above it, Newton's law cannot be used will-nilly
to say thay that there was some kind of action, so this must be the
reaction. You have to attribute the forces to their sources.

In this case, someone said Newtons law had to be use under penalty of
death, it would be simple:

Take a thin layer or air right at the boundary between the void and
ambient air. If another thin layer of ambient air pushes against this
thin layer, the thin layer will will push back against the ambient
thin layer. This is reciprocity of forces. The reason that the first
thin layer "loses" the pushing battle is because there nothing to
oppose the first thin layer as it moves into the void. The molecules
of the second thin layer has its friends to contend with. After the
first thin layer has moved into the void, those molecules can no
longer participate in pushing at the ambient air (because they have
assumed new position in space - neither air nor people are
telekinetic) and thus we get air flow.

Of course, there are not layers, but a distribution of momentum of the
particles, but this is close enough.

So in summary, downwash cause by high ambient pressure confronting a
void must not be used to contribute to lifting force of the wing. One
_can_ say that the pressure under the wing see no opposing force in
the relative void above the wing does result in net upward force.

-Le Chaud Lapin-

Dudley Henriques[_2_]

October 4th 07, 10:44 AM

Bertie the Bunyip wrote:
> Dudley Henriques > wrote in
> :
>
>> TheSmokingGnu wrote:
>>> Dudley Henriques wrote:
>>>> Crash Lander wrote:
>>>>> I'd like to see what his thoughts are on String Theory.
>>>>> LOL.
>>> >
>>>> I'm sure he'd most likely say that twine was better :-))
>>>>
>>> What, and discount the obvious implications that Duct Tape has on
>>> modern thinking?
>>>
>>> TheSmokingGnu
>> Ah, duct tape!! Where would aviation be without it ?
>>
>
> Absolutely. Or speed tape if you go a bit faster.
>
>
>
> Bertie

NASCAR!!!! Great folks!
D

--
Dudley Henriques

B A R R Y[_2_]

October 4th 07, 12:21 PM

TheSmokingGnu wrote:

>
> Then why do wings generate lift at negative AOA? Surely the immense
> vacuum pressures generated would immediately pull any flying craft
> desperately into the Earth the moment the wing crossed that threshold
> (say, in a descent).

Think "Relative Wind". Then rethink negative AOA.

Tina

October 4th 07, 12:39 PM

Still waiting for the conservation of momentum derivation. My husband,
also trained as an engineer, casually remarked he didn't think you
could get from Newton's First Law to there: that confirms my memory,
but we are both willing to have that belief rebutted.

He also pointed out that how a CFI might explain how a VOR works would
not satisfy an engineer. For that matter, the physics of flight as
explained to a student pilot would not satisfy someone who might be
interested in designing, as opposed to flying, an airplane, but I
don't think the manuals you are looking at are in error. I would point
out that each field has its own language, and you denying the
conventions used in aviation -- drag, lift and so on -- demonstrates
an unbecoming trait for a student, and even a worse one for an
employee. You may want to rething that attitude if you use it in real
life.

On Oct 3, 11:14 pm, Le Chaud Lapin > wrote:
> On Oct 3, 8:38 pm, Tina > wrote:
>
> > "We" are not in need of getting to the bottom of this. Most of us have
> > been there and done that.This particular writer, if she chooses to
> > analyse physics problems, tends to use the Newtonion approximations as
> > first principles. The good news is my profession doesn't demand those
> > skills often. I would, however, be interested, as I mentioned earlier,
> > how you derive conservation of mV from Newton's force/acceleration
> > relationship. I think you made that claim earlier in this thread.
>
> Hmm...I was afraid you would say that.
>
> A non-hand-waving explanation would too close to the quantum, and
> so...it's a bit much to discuss, at least right now. I've posted more
> messages in this thread in small period of time than I have ever for
> any other topic, in the history of using USENET, or...as one might
> say, dN/dt >> 0, where N is number of messages.
>
> -Le Chaud Lapin-

Mxsmanic

October 4th 07, 01:20 PM

Crash Lander writes:

> I'd like to see what his thoughts are on String Theory.

String theory is a theory based on math rather than physical reality.

Mxsmanic

October 4th 07, 01:24 PM

Le Chaud Lapin writes:

> I am not an expert either, but I know enough to know that the
> explanations I am reading in books are, at best, misleading.

That's an open secret in aviation. The mechanism of lift has been widely
explained incorrectly for years.

Mxsmanic

October 4th 07, 01:26 PM

Le Chaud Lapin writes:

> Yes, I am. It's a combination of many things taking place at once.
> Vacuum generation by the forward motion of the wing is one of them.

Gravity does that, not the forward motion of the wing. Without gravity, the
wing would simply move upwards until the effective angle of attack were no
longer positive.

Mxsmanic

October 4th 07, 01:27 PM

TheSmokingGnu writes:

> Then why do wings generate lift at negative AOA?

They don't. That's a very common misconception, even among pilots.

The effective AOA is always positive when the wing is generating lift.

Mxsmanic

October 4th 07, 01:31 PM

Le Chaud Lapin writes:

> By the bottom part of the wing, right?

Any displacement of mass downward will produce a matching upward forced. You
could generate lift of a sort by launching rocks off the wing, but you'd soon
run out of rocks so that's not very practical. But there's plenty of air
mass, so if you can find a way to divert it, you can generate lift.

> If you have compression under a wing do to extended flaps and laminar
> friction of airflow, for example, then the lower surface of the wing
> forces air downward, and the air beneath the lower surface forces wing
> upward.

In reality, the high pressure effects below the airfoil are almost
insignificant. The lift is generated mostly by the diversion of air flowing
over the wing downward.

Why is this all so important?

Tina

October 4th 07, 04:12 PM

Interested readers might enjoy looking at alphatrainers.com for a
discussion of lift. Mx's assertion that lift is mostly the result of
downwash flies (pardon the pun) in the face of 'center of lift'
analysis which in effect is that point on the wing where if for
balance considerations the integrated upward forces were concentrated
they could be considered to be operating at a point. If downwash, the
center of action of which is somewhat aft of the following edge of the
wing, was the major contributer of lift, one would expect the center
of lift to be in that area -- aft of the wing. It's not.

But what do I know, I'm just a psychologist -- with a minor in
physics.

[email protected]

October 4th 07, 04:49 PM

On Oct 4, 6:27 am, Mxsmanic > wrote:
> TheSmokingGnu writes:
> > Then why do wings generate lift at negative AOA?
>
> They don't. That's a very common misconception, even among pilots.
>
> The effective AOA is always positive when the wing is generating lift.

Once again, thou knowest not of what thou speakest. I
just told you, in apost not long ago, that some airfoils will generate
lift at up to -4° AOA. Here's a graph that shows lift being generated
on some anonymous airfoil at -5°:
http://en.wikipedia.org/wiki/Lift_coefficient
Bernoulli at work. Newton, too, because there's downwash being
generated.

Dan

Mxsmanic

October 4th 07, 04:56 PM

Tina writes:

> Interested readers might enjoy looking at alphatrainers.com for a
> discussion of lift. Mx's assertion that lift is mostly the result of
> downwash flies (pardon the pun) in the face of 'center of lift'
> analysis which in effect is that point on the wing where if for
> balance considerations the integrated upward forces were concentrated
> they could be considered to be operating at a point. If downwash, the
> center of action of which is somewhat aft of the following edge of the
> wing, was the major contributer of lift, one would expect the center
> of lift to be in that area -- aft of the wing. It's not.

I don't understand how you reached this conclusion. It's a bit like saying
that all of the planet Earth must be massless except for a dimensionless point
at its center, since that is where the center of gravity is.

> But what do I know, I'm just a psychologist -- with a minor in
> physics.

Knowledge is more important than credentials.

Mxsmanic

October 4th 07, 04:59 PM

writes:

> Once again, thou knowest not of what thou speakest.

Several others from the treehouse club here have told you the same thing.

No positive AOA, no lift. Learning this is extremely useful to pilots.

> I just told you, in apost not long ago, that some airfoils will generate
> lift at up to -4° AOA.

No airfoil generates lift at a negative angle of attack.

> Here's a graph that shows lift being generated
> on some anonymous airfoil at -5°:
> http://en.wikipedia.org/wiki/Lift_coefficient

Would you like me to draw a graph that shows something different and upload it
in place of that one?

Dudley Henriques[_2_]

October 4th 07, 05:01 PM

wrote:
> On Oct 4, 6:27 am, Mxsmanic > wrote:
>> TheSmokingGnu writes:
>>> Then why do wings generate lift at negative AOA?
>> They don't. That's a very common misconception, even among pilots.
>>
>> The effective AOA is always positive when the wing is generating lift.
>
> Once again, thou knowest not of what thou speakest. I
> just told you, in apost not long ago, that some airfoils will generate
> lift at up to -4° AOA. Here's a graph that shows lift being generated
> on some anonymous airfoil at -5°:
> http://en.wikipedia.org/wiki/Lift_coefficient
> Bernoulli at work. Newton, too, because there's downwash being
> generated.
>
> Dan
>

Don't bother. Believe me it's not worth it. You can talk this guy to
death and all he will do is count you as another response.

Angle of attack as we all know (with one exception it seems :-) can be
both positive or negative.
In fact, in high performance jets with a fuselage loaded IYMP, entering
a coupled spin after a departure, it's extremely disorienting if the
aircraft goes through PSG and stabilizes in an inverted spin mode where
yaw is opposite to roll. g is a bad indicator as with a fuselage loaded
IYMP you can get negative g either erect or inverted.
The way we deal with this is through instrument interpretation rather
than trying to eyeball what's happening, which can be next to impossible.
The AOA indicator in the aircraft has a positive and negative side. If
the AOA is stabilized at some value on the negative side, and the
airspeed is stabilized at some mean low value, the spin is inverted. The
turn needle will show spin direction either way.

Again, don't waste your time.

--
Dudley Henriques

Tina

October 4th 07, 05:10 PM

Mr Dudley, once again you are confused. Most define angle of attack as
the chord line of a wing, and of course with that definition it can be
negative and still generate lift. Mr Mx chooses a different way of
defining it. It is some angle such that when it goes negative the
airfoil can generate no lift. Do you remember the disbarred former
president Clinton saying something about "It depends on what 'is'
means"?

In Mx's case, words change meaning so that he is NEVER wrong. It must
be an interesting version of English he teaches.

But he does offer amusement for some of us on otherwise humorless
days, doesn't he?

Dudley Henriques[_2_]

October 4th 07, 05:23 PM

Tina wrote:
> Mr Dudley, once again you are confused. Most define angle of attack as
> the chord line of a wing, and of course with that definition it can be
> negative and still generate lift. Mr Mx chooses a different way of
> defining it. It is some angle such that when it goes negative the
> airfoil can generate no lift. Do you remember the disbarred former
> president Clinton saying something about "It depends on what 'is'
> means"?
>
> In Mx's case, words change meaning so that he is NEVER wrong. It must
> be an interesting version of English he teaches.
>
> But he does offer amusement for some of us on otherwise humorless
> days, doesn't he?
>
>

AOA actually can be defined relative to any given reference datum, but
normally it's considered in the industry as being the angle formed
between the chord line of the wing and the relative wind as you have
correctly stated.

Quite frankly, I read what Mxemanic writes on occasion and can't figure
out how he can be so close to getting it right and still manage to get
it wrong. He's amazing, and an interesting study if nothing else.
It's too bad he's taken this path on these groups. I've always felt he
has a genuine interest in things aviation and would like to contribute,
but he seems to be such a jerk that he gets in his own way.

--
Dudley Henriques

Le Chaud Lapin

October 4th 07, 05:47 PM

On Oct 4, 6:39 am, Tina > wrote:
> Still waiting for the conservation of momentum derivation. My husband,
> also trained as an engineer, casually remarked he didn't think you
> could get from Newton's First Law to there: that confirms my memory,
> but we are both willing to have that belief rebutted.

My apologies for broaching the subject. Frankly, I would rather save
it for the physicists. :)

> He also pointed out that how a CFI might explain how a VOR works would
> not satisfy an engineer. For that matter, the physics of flight as
> explained to a student pilot would not satisfy someone who might be
> interested in designing, as opposed to flying, an airplane, but I
> don't think the manuals you are looking at are in error.

If the manuals are in error, then they are in error. If the manual
issues a disclaimer, saying something, like, "this is not really what
is happening, but this will suffice for us..." that would be ok.
That's not what's happening. The manual mentions things like
Bernoulli, Newtons laws of motion. It even uses vector notation for a
few of the formula's. When one gets that close to the merchandise,
they need to purchase it.

> I would point
> out that each field has its own language, and you denying the
> conventions used in aviation -- drag, lift and so on -- demonstrates
> an unbecoming trait for a student, and even a worse one for an
> employee. You may want to rething that attitude if you use it in real
> life.

There is a difference between convention and errononeous information.
I never discounted drag, lift, or so on...I discounted the
explanations given some of my flight education materials. If it's
wrong, it's wrong. If someone reading it gets comfort from thinking
they understand, or whatever, that's fine for that person. But the
writers of those manuals should know that their audience is broad, and
should not publish erroneous information (after they know that it is
erroneous). There is gross difference between explaining something in
simple terms and being correct, versus explaining something in
moderately-difficult terms, and being incorrect.
I could probably explain VOR to a 10-year-old, without ever mentioning
things like counters, angular frequency, anisotropic radiation,
frequency bands, sub-carriers, convolution, etc....and my explanation
would still be correct.

"When you drink from a straw, there is no suction force."

-Le Chaud Lapin-

Jim Logajan

October 4th 07, 07:15 PM

Tina > wrote:
> Still waiting for the conservation of momentum derivation. My husband,
> also trained as an engineer, casually remarked he didn't think you
> could get from Newton's First Law to there: that confirms my memory,
> but we are both willing to have that belief rebutted.

You can't get conservation of momentum from F = m*a (or vice versa) since
the latter is not a statement about anything being conserved. But you can
get "For every force there is an equal opposite force" from conservation
of momentum, and vice versa, with a small number of assumptions. You can
use derivatives to derive one way and integration to derive the other.
Here are several conservation laws that share a common derivation,
starting with:

Center of Mass is Conserved
---------------------------
Center of mass of a closed system of particles of mass m1, m2, m3, ... mn
must remain fixed for all time, which with a suitable selection of
coordinate origins may be stated mathematically as:

(a) m1*x1 + m2*x2 + m3*x3 + ... = 0
m1*y1 + m2*y2 + m3*y3 + ... = 0
m1*z1 + m2*z2 + m3*z3 + ... = 0

Note that this doesn't say that, for example, x1 can't vary with time. It
only says that if it does then m1, m2, m3, x2 or x3 or other masses or
positions must somehow change so the left hand side still remains zero.

Momentum is Conserved
---------------------
If position with respect to time is continuous (no discontinuities; e.g.
no jumps) then we can take the time derivative of the above, yielding:

(b) m1*dx1/dt + m2*dx2/dt + m3*dx3/dt + ... = 0
(And so on for the other coordinate axis.)

This is of course just the conservation of momentum equations because
dx1/dt = Vx1, a velocity. Note that d(m1*x1)/dt would have been more
appropriate if the mass of particles varies with time.

Force is Conserved
------------------
Given the continuity assumption above, then we can keep taking time
derivatives of the above, yielding the next conservation statement:

(c) m1*d^2(x1)/dt^2 + m2*d^2(x2)/dt^2 + m3*d^2(x3)/dt^2 + ... = 0
(And so on for the other coordinate axis.)

This is of course just the old equal and opposite action statement in
mathematical form because d^2(x1)/dt^2 = ax1, an acceleration.

So if one claims any _one_ of the above conservation laws exists then the
other two appear to follow with only a small set of (presumably
reasonable) assumptions.

[email protected]

October 4th 07, 07:51 PM

On Oct 4, 10:47 am, Le Chaud Lapin > wrote:

> I could probably explain VOR to a 10-year-old, without ever mentioning
> things like counters, angular frequency, anisotropic radiation,
> frequency bands, sub-carriers, convolution, etc....and my explanation
> would still be correct.

I doubt it. The ten-year-old, and most flight students,
have absolutely no frame of reference to understand any of this in any
depth. I teach a College course on Aircraft Systems, and I have to
keep things really simple so they can grasp a few basics. If you are
an electrical engineer, and I've had a few in my classes, we can get
more into the workings of the VOR, but we leave all the others yawning
and wondering if this is going to be on the final exam.
When we come to hydraulics, we talk about pressure, volume
and area and relate that to what we experience as kids playing with a
garden hose. The same analogy can be used to a limited extent when
explaining Ohm's Law. But now I encounter kids who grew up in
highrises and never squirted their sisters with a hose, so they have
more difficulty. Too much information, not enough relationship to
previous bases because there are none.
You have no frame of reference yet. When you start getting
into violent departure stalls, skidding-turn spins, accelerated
stalls, spirals and the like, the sounds and forces start to make the
textbook stuff real. Sure, Jeppesen isn't always right. I haven't
found a textbook yet that doesn't have some glaring errors, and the
one I use in the Systems class has at least four that I have to issue
corrections on in the syllabus. And the writers of texts have found
that they don't sell the books that go into thousands of pages of
detail; the students have neither the inclination for it nor the time.
They have careers in other fields. So the textbook authors keep it
really simple in the hope that the student will be piqued enough to
dig further on his own. Most don't.
You an argue this as long as you want, like Mx, but it's all
book-learnin' and when the ground starts to come up at you real quick
it won't matter one bit. You WILL want to understand AOA and where you
went wrong.

Dan
Flight Instructor
Aircraft Maintenance Engineer

Le Chaud Lapin

October 4th 07, 08:42 PM

On Oct 4, 1:51 pm, wrote:
> On Oct 4, 10:47 am, Le Chaud Lapin > wrote:
>
> > I could probably explain VOR to a 10-year-old, without ever mentioning
> > things like counters, angular frequency, anisotropic radiation,
> > frequency bands, sub-carriers, convolution, etc....and my explanation
> > would still be correct.
>
> I doubt it. The ten-year-old, and most flight students,
> have absolutely no frame of reference to understand any of this in any
> depth. I teach a College course on Aircraft Systems, and I have to
> keep things really simple so they can grasp a few basics. If you are
> an electrical engineer, and I've had a few in my classes, we can get
> more into the workings of the VOR, but we leave all the others yawning
> and wondering if this is going to be on the final exam.
> When we come to hydraulics, we talk about pressure, volume
> and area and relate that to what we experience as kids playing with a
> garden hose. The same analogy can be used to a limited extent when
> explaining Ohm's Law. But now I encounter kids who grew up in
> highrises and never squirted their sisters with a hose, so they have
> more difficulty. Too much information, not enough relationship to
> previous bases because there are none.
> You have no frame of reference yet. When you start getting
> into violent departure stalls, skidding-turn spins, accelerated
> stalls, spirals and the like, the sounds and forces start to make the
> textbook stuff real. Sure, Jeppesen isn't always right. I haven't
> found a textbook yet that doesn't have some glaring errors, and the
> one I use in the Systems class has at least four that I have to issue
> corrections on in the syllabus. And the writers of texts have found
> that they don't sell the books that go into thousands of pages of
> detail; the students have neither the inclination for it nor the time.
> They have careers in other fields. So the textbook authors keep it
> really simple in the hope that the student will be piqued enough to
> dig further on his own. Most don't.
> You an argue this as long as you want, like Mx, but it's all
> book-learnin' and when the ground starts to come up at you real quick
> it won't matter one bit. You WILL want to understand AOA and where you
> went wrong.

I agree with everything you wrote except this last part and the part
about the 10-year-old. I have teaching experience myself in
electrical engineering, and mathematics, computer science, ...all, non-
trivial. I have found that very many complex things can be taught to
people while still remaining honest. Certainly there might not be
utlization of Maxwell's equations or partial-differential equations,
or red-black trees, but insight can be instilled that will give the
student an understanding that is both intutive and accurate. As the
student matures, the depth of understanding might increase, but it can
at least remain true. Schools try hard to do this, but since there
are so many students in class at once, each with different proclivity
to learn, the curriculum, by necessity, quickly suffers from rote
drill, as you hinted at. I remember being introduced to notion of
sqare-root of negative number in elementrary school. Then middle
school. Then again in high school. I never really understod them in
middle school because the teachers would not allow that. All the
students were in monkey mode. I also remember when I first did long
division, I and wanted to move on to what was next, and the teachers
would not allow it. I was forced to do hundreds of long-division
problems, one after the other, like a pencil monkey, even though it
was quite apparent what was going on. It was their way of keeping me
occupied.

This was OK for square-root of -1.

I do not think it is OK for flying. I want theory and the practice,
because with flying, I think it is more relevant. I don't want to be
in the cockpit flying around my friends and their children harboring
the secret that regarded the KT as an impediment to me having some fun
yankin' and bankin'. It's irresponsible. And if there is a crash due
to pilot error because of shallow understanding...

....that's simply unacceptable in my book, especially when I have
passengers.

-Le Chaud Lapin-

Paul Riley

October 4th 07, 10:27 PM

"Dudley Henriques" > wrote in message
...
> TheSmokingGnu wrote:
>> Dudley Henriques wrote:
>>> Crash Lander wrote:
>>>> I'd like to see what his thoughts are on String Theory.
>>>> LOL.
>> >
>>> I'm sure he'd most likely say that twine was better :-))
>>>
>>
>> What, and discount the obvious implications that Duct Tape has on modern
>> thinking?
>>
>> TheSmokingGnu
>
> Ah, duct tape!! Where would aviation be without it ?
>
> --
> Dudley Henriques

Hey, don't knock duct tape( we called it speed tape <G>). Kept water out of
my wing tank in Vietnam (Bird Dog) years ago. .50 cal rounds do a nasty job,
even on self sealing tanks. :-)))))

What the hey, even with one tank, for 2 hours, I still could fly the thing.
And did, for about 2 weeks.
:-)))))))))

Paul

Crash Lander[_1_]

October 5th 07, 12:23 AM

"Mxsmanic" > wrote in message
...
> Crash Lander writes:
>
>> I'd like to see what his thoughts are on String Theory.
>
> String theory is a theory based on math rather than physical reality.

And we all know math has absolutely nothing to do with physical reality eh?
Crash Lander
--
Straight and Level Down Under.
http://www.straightandleveldownunder.net/

Tina

October 5th 07, 12:26 AM

Of course, but the specific statement I wanted made clear had to do
with getting conservation of momentum from Newton's relationship
between force, mass, and acceleration. The OP claimed to be an
engineer, he was suggesting something I thought was unlikely and you
demonstrated that nicely.

Tina

October 5th 07, 12:29 AM

I thought it was called 100 kt tape, but if it walks like a duct and
talks like a . . . .

I'll have another glass of wine now..

Dudley Henriques[_2_]

October 5th 07, 12:31 AM

Tina wrote:
> I thought it was called 100 kt tape, but if it walks like a duct and
> talks like a . . . .
>
>
> I'll have another glass of wine now..
>

Ouch!!! Could it be that Shakespeare was right?

--
Dudley Henriques

Jim Logajan

October 5th 07, 12:48 AM

Tina > wrote:
> Of course, but the specific statement I wanted made clear had to do
> with getting conservation of momentum from Newton's relationship
> between force, mass, and acceleration. The OP claimed to be an
> engineer, he was suggesting something I thought was unlikely and you
> demonstrated that nicely.

Didn't he say he was an electronics engineer? Unless he's doing work on
electromechanical devices I can see how one can get rusty on dynamics.

I'm not sure questions regarding lift belong in a piloting group anyway.
Fluid dynamics is a particularly difficult subject because it is easy to
overlook things, such as: if a wing accelerates air downward, then
according to conservation of momentum some other mass must be accelerated
upward.

Bertie the Bunyip

October 5th 07, 12:53 AM

Mxsmanic wrote:
> Le Chaud Lapin writes:
>
> > Yes, I am. It's a combination of many things taking place at once.
> > Vacuum generation by the forward motion of the wing is one of them.
>
> Gravity does that, not the forward motion of the wing. Without gravity, the
> wing would simply move upwards until the effective angle of attack were no
> longer positive.

Good grief.

Bertie

Bertie the Bunyip

October 5th 07, 12:54 AM

Le Chaud Lapin wrote:
> On Oct 3, 9:26 pm, TheSmokingGnu
> > wrote:
> > Le Chaud Lapin wrote:
> > > You can have lift of an object with no Bernoulli. It's simple vector
> > > addition.
> >
> > 1. You are talking about nature's abhorrence of a vacuum.
> > 2. Vacuum abhorrence is not lift.
> > 3. Airplanes do not generate lift as a result of vacuum abhorrence.
> > ----------
> > Conclusion: you are not talking about how aircraft generate lift.
>
> Yes, I am. It's a combination of many things taking place at once.
> Vacuum generation by the forward motion of the wing is one of them.
>

Enjoying yourself there Anthony_

i know I am!

Bwaahwahwhahwhahwhahwhahwhahwhahwhha!

Bertie

Bertie the Bunyip

October 5th 07, 12:56 AM

Morgans wrote:
> "Morgans" <> wrote
> >
> > It goes something like this.
> >
> > An airplane is about to takeoff on a runway, that is really a treadmill; a
> > very expensive treadmill.
> >
> > The treadmill senses the airplane's speed, and matches the aircraft's
> > speed, with speed increases of its own.
> >
> > Can the airplane takeoff? Why or why not?
>
> I forgot one important qualifier of the treadmill's operation.
>
> It goes in the opposite direction of the intended direction of travel for
> the airplane.

Oh god,. imagine having been hios spiritual teacher when he was
young.

Do dogs get into heaven, et al...

Bertie

Bertie the Bunyip

October 5th 07, 12:58 AM

Le Chaud Lapin wrote:
> On Oct 3, 8:29 pm, wrote:
> > After all the years of reading this stuff and seeing wind-
> > tunnel demos and graphs and all such, I know there's an awful lot of
> > information out there on the generation of lift. Most of it is
> > available on the 'net. The strangest thing is the newbie who starts to
> > argue with his textbooks, very publicly (as on a newsgroup) without
> > Googling it for himself first. He knows better, he's sure.
>
> What's strange is CFI'S (two of them) who did not know how to explain
> VOR to an electrial engineer (me), who, after reading the discription
> of how it works, could probably make after reading the technical
> specs.

Doesn#t matter how it works.

It does work, and lasts a long time. That#s all pilots need to know,
fjukkwit.

>
> What's strange is one of the recognized leaders in flight training
> materials using words like "energy" when they mean "power". I might
> be a newbie to flying, but I'm not a newbie to physics.

And my guess is you´ßre going to be a permanent newbie to flying.

Bertie

Bertie the Bunyip

October 5th 07, 12:59 AM

Mxsmanic wrote:
> Le Chaud Lapin writes:
>
> > I am not an expert either, but I know enough to know that the
> > explanations I am reading in books are, at best, misleading.
>
> That's an open secret in aviation. The mechanism of lift has been widely
> explained incorrectly for years.

Really_ i´ve nly seen you trying to explain it for a few months now.

Take up the baton from someone else, did you_

Bertie

Tony

October 5th 07, 01:02 AM

Jim, I guess it depends on the institution and the intellegence of the
student. My husband graduated even longer ago than I did with degrees
in electronics, but he was well trained in mechanics as well. It may
be the newer schools don't offer as broad a base in classical
mechanics and physics.

What is especially interesting is that theories are offered that do
not predict observations very well. I skydived a few times, and my
sensation was that my arched body (the negative of a classic airfoil)
was being supported by a pillow of air, not being drawn up into a
partial vacuum. In fact if memory serves I don't remember the jump
suits of others bellowing in the back either.

And if one holds one's hand out of a car window, the psudo lift
provided by air deflecting from the surface facing the wind does not
seem to come from something at the trailing edge -- in fact one can
put one's wrist in the trailing position and still feel the same
impact -- delta momentum - forces.

For a theory to be accepted it has to predict observations. Trailing
edge downwash and some other things written here don't seem to do
that. But it is fun. Shall we talk about flying a kind of roll with
having the pilot experience exactly 1 G into the seat during the
sequence? That is about as much fun as talking about an airplane take
off from a belt sander, or taking off into a 70 KT headwind, turning
downwind and not falling out of the sky.

On Oct 4, 7:48 pm, Jim Logajan > wrote:
> Tina > wrote:
> > Of course, but the specific statement I wanted made clear had to do
> > with getting conservation of momentum from Newton's relationship
> > between force, mass, and acceleration. The OP claimed to be an
> > engineer, he was suggesting something I thought was unlikely and you
> > demonstrated that nicely.
>
> Didn't he say he was an electronics engineer? Unless he's doing work on
> electromechanical devices I can see how one can get rusty on dynamics.
>
> I'm not sure questions regarding lift belong in a piloting group anyway.
> Fluid dynamics is a particularly difficult subject because it is easy to
> overlook things, such as: if a wing accelerates air downward, then
> according to conservation of momentum some other mass must be accelerated
> upward.

TheSmokingGnu

October 5th 07, 01:10 AM

Dudley Henriques wrote:
> Tina wrote:
>> I thought it was called 100 kt tape, but if it walks like a duct and
>> talks like a . . . .
>>
>>
>> I'll have another glass of wine now..
>>
>
> Ouch!!! Could it be that Shakespeare was right?
>

"A duct by any other name would be just as sticky..."

:D

TheSmokingGnu

Le Chaud Lapin

October 5th 07, 01:24 AM

On Oct 4, 6:58 pm, Bertie the Bunyip >
wrote:
> Le Chaud Lapin wrote:
> > What's strange is CFI'S (two of them) who did not know how to explain
> > VOR to an electrial engineer (me), who, after reading the discription
> > of how it works, could probably make after reading the technical
> > specs.
>
> Doesn#t matter how it works.
> It does work, and lasts a long time. That#s all pilots need to know,
> fjukkwit.

Sounds like you've been using Viagra.

> And my guess is you´ßre going to be a permanent newbie to flying.

Ess-Tsett and # symbols. Hmmm...

Either you're German, drunk, or both.

-Le Chaud Lapin-

Bertie the Bunyip

October 5th 07, 01:31 AM

Mxsmanic wrote:
> Tina writes:
>
> > Interested readers might enjoy looking at alphatrainers.com for a
> > discussion of lift. Mx's assertion that lift is mostly the result of
> > downwash flies (pardon the pun) in the face of 'center of lift'
> > analysis which in effect is that point on the wing where if for
> > balance considerations the integrated upward forces were concentrated
> > they could be considered to be operating at a point. If downwash, the
> > center of action of which is somewhat aft of the following edge of the
> > wing, was the major contributer of lift, one would expect the center
> > of lift to be in that area -- aft of the wing. It's not.
>
> I don't understand how you reached this conclusion. It's a bit like saying
> that all of the planet Earth must be massless except for a dimensionless point
> at its center, since that is where the center of gravity is.
>
> > But what do I know, I'm just a psychologist -- with a minor in
> > physics.
>
> Knowledge is more important than credentials.

Ability is more important than either, fjukkwit#

Bertie

Morgans[_2_]

October 5th 07, 03:00 AM

"Paul Riley" > wrote
>
> Hey, don't knock duct tape( we called it speed tape <G>). Kept water out
> of my wing tank in Vietnam (Bird Dog) years ago. .50 cal rounds do a nasty
> job, even on self sealing tanks. :-)))))
>
> What the hey, even with one tank, for 2 hours, I still could fly the
> thing. And did, for about 2 weeks.
> :-)))))))))

I used to call it 200 MPH tape, because that's about how fast they go in
NASCAR. Then I got to know a Master Chief that was serving on carriers,
working on Hornets.

Then he tells me they were using it in the first Gulf War, and on F-18's, at
that! Now I have to call it 1,500 MPH tape!

No doubt that they are still using it now, for much the same purposes, I'll
bet.

1,500 MPH tape just doesn't have the same ring. It doesn't roll off the
tongue as smoothly. <g>

Wonderful stuff, huh?
--
Jim in NC

Paul Riley

October 5th 07, 03:05 AM

That is why we called it "speed tape"--fit all situations!!!! :-))))))

Paul
"Morgans" > wrote in message
...
>
> "Paul Riley" > wrote
>>
>> Hey, don't knock duct tape( we called it speed tape <G>). Kept water out
>> of my wing tank in Vietnam (Bird Dog) years ago. .50 cal rounds do a
>> nasty job, even on self sealing tanks. :-)))))
>>
>> What the hey, even with one tank, for 2 hours, I still could fly the
>> thing. And did, for about 2 weeks.
>> :-)))))))))
>
> I used to call it 200 MPH tape, because that's about how fast they go in
> NASCAR. Then I got to know a Master Chief that was serving on carriers,
> working on Hornets.
>
> Then he tells me they were using it in the first Gulf War, and on F-18's,
> at that! Now I have to call it 1,500 MPH tape!
>
> No doubt that they are still using it now, for much the same purposes,
> I'll bet.
>
> 1,500 MPH tape just doesn't have the same ring. It doesn't roll off the
> tongue as smoothly. <g>
>
> Wonderful stuff, huh?
> --
> Jim in NC
>

Matt Whiting

October 5th 07, 03:14 AM

Morgans wrote:
> "Paul Riley" > wrote
>> Hey, don't knock duct tape( we called it speed tape <G>). Kept water out
>> of my wing tank in Vietnam (Bird Dog) years ago. .50 cal rounds do a nasty
>> job, even on self sealing tanks. :-)))))
>>
>> What the hey, even with one tank, for 2 hours, I still could fly the
>> thing. And did, for about 2 weeks.
>> :-)))))))))
>
> I used to call it 200 MPH tape, because that's about how fast they go in
> NASCAR. Then I got to know a Master Chief that was serving on carriers,
> working on Hornets.
>
> Then he tells me they were using it in the first Gulf War, and on F-18's, at
> that! Now I have to call it 1,500 MPH tape!
>
> No doubt that they are still using it now, for much the same purposes, I'll
> bet.
>
> 1,500 MPH tape just doesn't have the same ring. It doesn't roll off the
> tongue as smoothly. <g>

That is because it isn't 1,500 MPH tape but rather Mach 2 tape!

Matt

Morgans[_2_]

October 5th 07, 03:24 AM

"Jim Logajan" > wrote

> Didn't he say he was an electronics engineer? Unless he's doing work on
> electromechanical devices I can see how one can get rusty on dynamics.

Jim, this is MX reborn. Give it up.
--
Jim in NC

Morgans[_2_]

October 5th 07, 04:09 AM

"Matt Whiting" <> wrote

> That is because it isn't 1,500 MPH tape but rather Mach 2 tape!

Ahh, that _does_ have a nicer ring to it, doesn't it!
--
Jim in NC

Bertie the Bunyip[_19_]

October 5th 07, 06:09 AM

Le Chaud Lapin > wrote in
oups.com:

> On Oct 4, 6:58 pm, Bertie the Bunyip >
> wrote:
>> Le Chaud Lapin wrote:
>> > What's strange is CFI'S (two of them) who did not know how to explain
>> > VOR to an electrial engineer (me), who, after reading the discription
>> > of how it works, could probably make after reading the technical
>> > specs.
>>
>> Doesn#t matter how it works.
>> It does work, and lasts a long time. That#s all pilots need to know,
>> fjukkwit.
>
> Sounds like you've been using Viagra.

Don't need it.

>
>> And my guess is you´ßre going to be a permanent newbie to flying.
>
> Ess-Tsett and # symbols. Hmmm...
>
> Either you're German, drunk, or both.
>

None of the above.

Bertie

Bertie the Bunyip[_19_]

October 5th 07, 06:10 AM

Le Chaud Lapin > wrote in
ups.com:

> On Oct 4, 1:51 pm, wrote:
>> On Oct 4, 10:47 am, Le Chaud Lapin > wrote:
>>
>> > I could probably explain VOR to a 10-year-old, without ever
mentioning
>> > things like counters, angular frequency, anisotropic radiation,
>> > frequency bands, sub-carriers, convolution, etc....and my
explanation
>> > would still be correct.
>>
>> I doubt it. The ten-year-old, and most flight students,
>> have absolutely no frame of reference to understand any of this in
any
>> depth. I teach a College course on Aircraft Systems, and I have to
>> keep things really simple so they can grasp a few basics. If you are
>> an electrical engineer, and I've had a few in my classes, we can get
>> more into the workings of the VOR, but we leave all the others
yawning
>> and wondering if this is going to be on the final exam.
>> When we come to hydraulics, we talk about pressure, volume
>> and area and relate that to what we experience as kids playing with a
>> garden hose. The same analogy can be used to a limited extent when
>> explaining Ohm's Law. But now I encounter kids who grew up in
>> highrises and never squirted their sisters with a hose, so they have
>> more difficulty. Too much information, not enough relationship to
>> previous bases because there are none.
>> You have no frame of reference yet. When you start
getting
>> into violent departure stalls, skidding-turn spins, accelerated
>> stalls, spirals and the like, the sounds and forces start to make the
>> textbook stuff real. Sure, Jeppesen isn't always right. I haven't
>> found a textbook yet that doesn't have some glaring errors, and the
>> one I use in the Systems class has at least four that I have to issue
>> corrections on in the syllabus. And the writers of texts have found
>> that they don't sell the books that go into thousands of pages of
>> detail; the students have neither the inclination for it nor the
time.
>> They have careers in other fields. So the textbook authors keep it
>> really simple in the hope that the student will be piqued enough to
>> dig further on his own. Most don't.
>> You an argue this as long as you want, like Mx, but it's
all
>> book-learnin' and when the ground starts to come up at you real quick
>> it won't matter one bit. You WILL want to understand AOA and where
you
>> went wrong.
>
> I agree with everything you wrote except this last part and the part
> about the 10-year-old. I have teaching experience myself in
> electrical engineering, and mathematics, computer science, ...all,
non-
> trivial.

Yeah, show all that to yor win, dip****.

rash due
> to pilot error because of shallow understanding...
>
> ...that's simply unacceptable in my book, especially when I have
> passengers.
>

Never going to happen, Anthony

Bertie

Bertie the Bunyip[_19_]

October 5th 07, 06:11 AM

Mxsmanic > wrote in
:

> Le Chaud Lapin writes:
>
>> I am not an expert either, but I know enough to know that the
>> explanations I am reading in books are, at best, misleading.
>
> That's an open secret in aviation. The mechanism of lift has been widely
> explained incorrectly for years.
>

You've only been explaining it for a few months, fjukktard, not years.

Bertie

Bertie the Bunyip[_19_]

October 5th 07, 06:12 AM

Mxsmanic > wrote in
:

> Crash Lander writes:
>
>> I'd like to see what his thoughts are on String Theory.
>
> String theory is a theory based on math rather than physical reality.
>

Much like your life.

Bertie

Bertie the Bunyip[_19_]

October 5th 07, 06:26 AM

"Morgans" > wrote in
:

>
> "Paul Riley" > wrote
>>
>> Hey, don't knock duct tape( we called it speed tape <G>). Kept water
>> out of my wing tank in Vietnam (Bird Dog) years ago. .50 cal rounds
>> do a nasty job, even on self sealing tanks. :-)))))
>>
>> What the hey, even with one tank, for 2 hours, I still could fly the
>> thing. And did, for about 2 weeks.
>> :-)))))))))
>
> I used to call it 200 MPH tape, because that's about how fast they go
> in NASCAR. Then I got to know a Master Chief that was serving on
> carriers, working on Hornets.
>
> Then he tells me they were using it in the first Gulf War, and on
> F-18's, at that! Now I have to call it 1,500 MPH tape!
>
> No doubt that they are still using it now, for much the same purposes,
> I'll bet.
>
> 1,500 MPH tape just doesn't have the same ring. It doesn't roll off
> the tongue as smoothly. <g>
>
> Wonderful stuff, huh?

The stuff they are using on the jets is a bit different than 200 mph tape.
It's kind of a thin but tough foil. It's actually legal for some repairs.
If you keep an eye out you might see it on the leading edge of a wing or
maybe holdin an oil door down on an engine where the fasteners have been
damaged.
It's good stuff and if ever I see a roll lying around it's in my flight
case faster'n you can say boo.,

Bertie

Gatt

October 5th 07, 11:12 PM

"Le Chaud Lapin" > wrote in message
oups.com...

> The air on the "outside" of the umbrella does *NOT* instantaneously
> fill the void that is created by yanking the umbrella.

All you need to change the known science of aerodynamics is a wind tunnel.
For example, some of your fellow aerospace scientists use this one:

http://www.ccastronomy.org/photo_NASA-Ames_2003-06-22-wer-14_640x480.jpg
http://www.windtunnels.arc.nasa.gov/pics/12FT/12ft2.html

It's amazing. They even have a supersonic wind tunnel so they can test
their aerodynamic ideas. Not only that, but they have a VR lab nearby that
lets them look at 3D renderings of the wind tunnel results.

-c

Gatt

October 5th 07, 11:42 PM

> wrote in message
oups.com...
> On Oct 3, 8:15 am, Le Chaud Lapin > wrote:
>
>> Actually I did because every book I read about flying skimped on the
>> subject. I'm going to hop over to MIT's OpenCourseWare later this
>> week and download their most basic course on aero/astro. Benoulli's
>> principle is toss around as if it were facecloth, but I'm getting the
>> feeling that no one is really doing the physics.

I SWEAR to you guys, somebody sounding conspicuously like him was out here
within the last couple of months refuting Bournoulli and referring to
pressure under the wing, making plywood fly, etc. Sounds awful familiar.

-c

[email protected]

October 6th 07, 12:32 AM

On Oct 5, 4:42 pm, "Gatt" > wrote:

> > On Oct 3, 8:15 am, Le Chaud Lapin > wrote:
>
> >> Actually I did because every book I read about flying skimped on the
> >> subject. I'm going to hop over to MIT's OpenCourseWare later this
> >> week and download their most basic course on aero/astro. Benoulli's
> >> principle is toss around as if it were facecloth, but I'm getting the
> >> feeling that no one is really doing the physics.
>
> I SWEAR to you guys, somebody sounding conspicuously like him was out here
> within the last couple of months refuting Bournoulli and referring to
> pressure under the wing, making plywood fly, etc. Sounds awful familiar.

It's familiar because there are many out there who don't
understand or don't agree with the textbooks. Even among experts
there's disagreement. Every so often one of them makes an issue of it.
It's quite normal, especially if they don't use the Google Groups
Search function first to see what the previous arguments have been on
the subject on a particular newsgroup.
It annoys some of us because the same arguments are put forth
repeatedly and we can't figure out why some don't get it. But it's no
different than my classroom, in which every new batch of students
brings the same misunderstandings and doubts and arguments. We were
young once, too, and didn't believe much of what our teachers were
trying to tell us.
Bernoulli said that moving air has a lower pressure than
static air. The air over the top of the wing is moving considerably
faster than that underneath, so it has lower pressure. It's not
rarefaction; it's the increase in dynamic pressure (velocity) that
subtracts from static pressure, the same phenomenon that makes a
turbine engine work so well.
Newton said that for every action there's an equal and
opposite reaction. If you look at the diagrams of airflow here,
http://www.av8n.com/how/htm/airfoils.html
scrolling down to Figure 3.2, you'll see that there's upwash ahead of
the wing as well as downwash behind it. the upwash is generated by the
approaching low pressure area above the wing. As the wing passes, the
upwash is converted to downwash; if this isn't Newton at work, I don't
know what is. Newton would be just another dead guy.
For the average PPL or CPL this should be sufficient. It's true
enough, even if it doesn't give the detail that the physicist would
like. As I said, most pilots have other careers and interests and they
find that Newton and Bernoulli jibe with what they experience in the
air, so they're satisfied. Making textbooks thicker or filling them
with competing theories does nothing but confuse these people.
If a student wants to argue that the physics as presented are
all wrong he should do extensive research and publish a book on the
subject, not argue with pilots who have been trusting their soft pink
bodies to Bernoulli and Newton for decades.

Dan

Dudley Henriques[_2_]

October 6th 07, 12:38 AM

wrote:
If a student wants to argue that the physics as presented are
> all wrong he should do extensive research and publish a book on the
> subject, not argue with pilots who have been trusting their soft pink
> bodies to Bernoulli and Newton for decades.
>
> Dan
>

You may add "wrinkled" to that list of adjectives for the "older" pilots
if you like
:-)

--
Dudley Henriques

Morgans[_2_]

October 6th 07, 12:55 AM

"Gatt" > wrote

> I SWEAR to you guys, somebody sounding conspicuously like him was out here
> within the last couple of months refuting Bournoulli and referring to
> pressure under the wing, making plywood fly, etc. Sounds awful familiar.

You don't have to convince me. This one is as bad a K00K as has been here
for a while, and that's saying something.

He can say he has not changed his handle until he is blue in the face, and I
won't believe it.
--
Jim in NC

Mxsmanic

October 6th 07, 01:14 AM

Crash Lander writes:

> And we all know math has absolutely nothing to do with physical reality eh?

Modern physicists tend to understand math but not physics. They develop their
theories in mathematical terms, and explain them in mathematical terms, but
when asked to explain them in physical terms are unable to do so. This makes
them different from their more illustrious predecessors. For these modern
physicists, math has replaced reality, because they don't really understand
reality. They believe that if the math works, that's reality. Unfortunately,
there are infinitely many mathematical models that will work, but they don't
necessarily have anything to do with reality.

You won't be able to find anyone who can explain string theory without using
math. But Einstein could explain physics without math.

Mxsmanic

October 6th 07, 01:20 AM

Tony writes:

> For a theory to be accepted it has to predict observations. Trailing
> edge downwash and some other things written here don't seem to do
> that.

Actually, downwash can be directly observed in appropriate atmospheric
conditions. There are pictures on the Web that illustrate this.

Remember, in order to accelerate something upward, something else must be
accelerated downward.

When you hold your hand out the window of a car at an angle, and you feel it
being raised, where does the energy to raise your hand come from?

Mxsmanic

October 6th 07, 01:21 AM

Bertie the Bunyip writes:

> Really_ i´ve nly seen you trying to explain it for a few months now.

Many books explain it incorrectly.

Mxsmanic

October 6th 07, 01:27 AM

Dudley Henriques writes:

> AOA actually can be defined relative to any given reference datum, but
> normally it's considered in the industry as being the angle formed
> between the chord line of the wing and the relative wind as you have
> correctly stated.

The angle of attack is the angle between the forward stagnation point and the
trailing stagnation point. The points of intersection of the chord line with
the airfoil surface are static, but the stagnation points can change, altering
the angle of attack.

If the angle of attack is not positive, there is no lift. You cannot have
lift at negative angles of attack because that is not symmetric. If a
negative angle of attack can produce positive lift, what happens when you turn
the airfoil upside down? Logically that would mean that even a positive angle
of attack would force the wing down, which makes no sense.

Mxsmanic

October 6th 07, 01:28 AM

Gatt writes:

> I SWEAR to you guys, somebody sounding conspicuously like him was out here
> within the last couple of months refuting Bournoulli and referring to
> pressure under the wing, making plywood fly, etc. Sounds awful familiar.

It's entirely possible for an opinion to be shared by several people, even if
that opinion is not shared by the president of the treehouse club.

Jim Logajan

October 6th 07, 02:48 AM

Mxsmanic > wrote:
> Modern physicists tend to understand math but not physics.

Then you should have no problem naming a few who exhibit this problem.

Mxsmanic

October 6th 07, 03:25 AM

Jim Logajan writes:

> Then you should have no problem naming a few who exhibit this problem.

The ones who have the problem are unimportant, as they don't really understand
physics, anyway.

Dudley Henriques[_2_]

October 6th 07, 04:08 AM

Jim Logajan wrote:
> Mxsmanic > wrote:
>> Modern physicists tend to understand math but not physics.
>
> Then you should have no problem naming a few who exhibit this problem.

Jim;
Why bother....really.

--
Dudley Henriques

Tina

October 6th 07, 04:49 AM

The physicists I know worry about confirming their calculations by
observation. I don't know who MX is referring to.

Pure math research doesn't need anything but internal consistancy, but
every worthwhile scientist is verifying by measurement, and the
measurements are becoming exquisitely accurate.

I wish I could be as predictive in my field as those in the hard
sciences are in theirs.

Le Chaud Lapin

October 6th 07, 07:14 AM

On Oct 5, 6:32 pm, wrote:
> It's familiar because there are many out there who don't
> understand or don't agree with the textbooks. Even among experts
> there's disagreement. Every so often one of them makes an issue of it.
> It's quite normal, especially if they don't use the Google Groups
> Search function first to see what the previous arguments have been on
> the subject on a particular newsgroup.

I'd like to first note something since I am newly exposed to this
field:

In electrical engineering, we have our own set of fundamental
principles. The "terminal" set of primitives governing electronics
(electrostatics and electrodynamics) is Maxwells Equations
http://en.wikipedia.org/wiki/Maxwell_equation. In EE, we have out
own myths, like power lines causing brain cancer, but when they arise,
the experts work hard to show indisputable evidence, verifiable,
rigorous evidence to the contrary, to nip the non-sense in the bud.
We do still have areas of disputes, like what causes shot noise in
circuits [http://en.wikipedia.org/wiki/Shot_noise], but on the bread-
and-butter basics, you won't find a college-leve textbook speaking
untruth. So naturally I am extremely surprised to see this happening
in aerodynamics. You are, after all, the rocket scientists. :)
[i]
> It annoys some of us because the same arguments are put forth
> repeatedly and we can't figure out why some don't get it. But it's no
> different than my classroom, in which every new batch of students
> brings the same misunderstandings and doubts and arguments. We were
> young once, too, and didn't believe much of what our teachers were
> trying to tell us.

Oh, I certainly don't believe what I wrote in the Jeppensen book. I
don't believe what the 3 CFI's told me recently. I don't believe what
my friends friend, the pilot, told me three years ago. And though I
would be highly honored if I could meet him, I don't believe what Rod
Machado, whom I think we would all agree is not exactly dumb nor a bad
teacher, nor ignorant in the field, wrote. I don't believe it for two
reasons:

1. It's obviously wrong if you read and interpret correctly what
Bernoulli wrote.
2. NASA says it's wrong. From Jim Logajan: http://www.grc.nasa.gov/WWW/K-12/airplane/bernnew.html

> Bernoulli said that moving air has a lower pressure than
> static air. The air over the top of the wing is moving considerably
> faster than that underneath, so it has lower pressure.

People are going to yell and boo me for saying this, but after taking
a nice long ride tonight on my motorcyle tonight, I thought the
venturi/Bernoulli thing through, and I am 95% certain that that is not
the reason the pressure is lower. In fact, I could probably provide an
experiment showing you a situation where air is moving considerably
faster on top than it is on the bottom, with much higher presure on
the top. What is ironic is that Bernoulli would still be right, but
the interpretation of Bernoulli would fall apart.

> It's not
> rarefaction; it's the increase in dynamic pressure (velocity) that
> subtracts from static pressure, the same phenomenon that makes a
> turbine engine work so well.

Not to nit-pick, but dynamic pressure is p(t), where t is time, and
velocity is d/dt R(t), where R is position vector, two totally
different things.

> Newton said that for every action there's an equal and
> opposite reaction. If you look at the diagrams of airflow here,http://www.av8n.com/how/htm/airfoils.html
> scrolling down to Figure 3.2, you'll see that there's upwash ahead of
> the wing as well as downwash behind it. the upwash is generated by the
> approaching low pressure area above the wing. As the wing passes, the
> upwash is converted to downwash; if this isn't Newton at work, I don't
> know what is. Newton would be just another dead guy.

Newton did say that. And I looked at that diagram very carefully.
[Thanks for link] The upwash is not casued by an approaching low
pressure. The upwash is caused by a gradient in pressure, going from
high pressure at the leading ede, to low pressure, right above and
slightly-back of the wing, due to rarefication of the wing in motion.
The area above the rarefication is normal atmosphere that has a
propensity to move toward the lower-pressure, rarefied air. The
combination of that normal atmosphere air, combine with the high
velocity of the molecules from the leading edge of the wing, results
in the flow paths (streams) that you see. I haven't looked yet, but I
imagine that there are aerodynamicists, all over the world, who, if
not for appreciation of the hypothesis I am proposing here, have at
least figured this out empircally, and are fretting day and night
trying to find the optimal shape of the leading edge of the wing.
They have two conflicting objectives:

1. Make the shape in such a way so as to minimize drag.
2. Make the shape in such a way so as to increase pressure to impart
high velocity to air molecules moving up/backwards.

I'll be the first to admit that i don't have the capacity to do so at
this moment, but imagine that that one shape of the leading edge is
not appropriate for all speeds of the aircraft. For a given set of
context variables like density, temperature, pressure, angle-of-
attack, airspeed, what-the-plane-was-doing-20-milliseconds-ago,
turbulences...wind, etc...there is an optimal shape for that leading
edge, depending on what you are trying to do. It would be quite wild
if someone were to design a wing that could morph, dynamically by
control of a computer, into an instaneously-optimal shape.

> For the average PPL or CPL this should be sufficient. It's true
> enough, even if it doesn't give the detail that the physicist would
> like. As I said, most pilots have other careers and interests and they
> find that Newton and Bernoulli jibe with what they experience in the
> air, so they're satisfied. Making textbooks thicker or filling them
> with competing theories does nothing but confuse these people.

I believe it should be possible to explain a venturi tube, Bernoulli's
principle, and a decent part of why a wing has lift, in about 2-3
pages of written text, with pictures, using no formulas, not even
grade-school mathematics.

> If a student wants to argue that the physics as presented are
> all wrong he should do extensive research and publish a book on the
> subject, not argue with pilots who have been trusting their soft pink
> bodies to Bernoulli and Newton for decades.

I definitely agree a paper should be written, and there should be an
element of rigor, obviously lacking in my posts. :)

However, I honestly think pilot's have been trusting neither Bernoulli
nor Newton. They are dead. But they each left a legacy, which,
according to the NASA links, have been misinterpreted and abused by
countless theoritsts and educators in this field. So one could say
that the pilots have been trusting these theorists and educators, but
perhaps not even that is the case. I think what Ron hinted at is most-
likely the case, that there is a phenomenon that would allow even a
Neanderthal to achieve technical advancement:

The Neanderthal starts with a contraption that works, and through much
trial-and-error, finds better and better rendentions of that same
contraption. Eventually, he will have something that works so well,
that the question of "Why" would hardly need be asked. Naturally,
theorists will tag along and try to explain with rigorous scientific
principles what he has accomplished with only raw will of spirit, but
the theory does not necessarily have to be right or complete get the
thing in the air. Of course, the Wright Brothers were high-minded
individuals, but I think you get the point.

One might ask, "Well if that is the case, then what is the point of
nit-picking with theory?"

It is because a theory that correctly explains observed phenomenon
generally opens up an entirely new world of order and efficiency.

-Le Chaud Lapin-

Bertie the Bunyip[_19_]

October 6th 07, 08:18 AM

Mxsmanic > wrote in
:

> Dudley Henriques writes:
>
>> AOA actually can be defined relative to any given reference datum,
>> but normally it's considered in the industry as being the angle
>> formed between the chord line of the wing and the relative wind as
>> you have correctly stated.
>
> The angle of attack is the angle between the forward stagnation point
> and the trailing stagnation point. The points of intersection of the
> chord line with the airfoil surface are static, but the stagnation
> points can change, altering the angle of attack.
>
> If the angle of attack is not positive, there is no lift. You cannot
> have lift at negative angles of attack because that is not symmetric.
> If a negative angle of attack can produce positive lift, what happens
> when you turn the airfoil upside down? Logically that would mean that
> even a positive angle of attack would force the wing down, which makes
> no sense.
>

Nope

Bertie

Bertie the Bunyip[_19_]

October 6th 07, 08:18 AM

Mxsmanic > wrote in
:

> Bertie the Bunyip writes:
>
>> Really_ i´ve nly seen you trying to explain it for a few months now.
>
> Many books explain it incorrectly.
>

So do you dip****.

Bertie

Bertie the Bunyip[_19_]

October 6th 07, 08:19 AM

Mxsmanic > wrote in
:

> Crash Lander writes:
>
>> And we all know math has absolutely nothing to do with physical
>> reality eh?
>
> Modern physicists tend to understand math but not physics. They
> develop their theories in mathematical terms, and explain them in
> mathematical terms, but when asked to explain them in physical terms
> are unable to do so. This makes them different from their more
> illustrious predecessors. For these modern physicists, math has
> replaced reality, because they don't really understand reality. They
> believe that if the math works, that's reality. Unfortunately, there
> are infinitely many mathematical models that will work, but they don't
> necessarily have anything to do with reality.
>
> You won't be able to find anyone who can explain string theory without
> using math. But Einstein could explain physics without math.
>

Wrong again. First thing he would have said after talking to you is "You
are one dumb mother****er"

That's math.

Bertie

Bertie the Bunyip[_19_]

October 6th 07, 08:20 AM

Mxsmanic > wrote in
:

> Jim Logajan writes:
>
>> Then you should have no problem naming a few who exhibit this
>> problem.
>
> The ones who have the problem are unimportant, as they don't really
> understand physics, anyway.
>

I do and you do not.

Waht's more, I can make fizziks dance at m fingertiips.

We al know waht dances at the end of your fingertips.

Bertie

Bertie the Bunyip[_19_]

October 6th 07, 08:22 AM

Tina > wrote in news:1191642553.306168.208000@
22g2000hsm.googlegroups.com:

> The physicists I know worry about confirming their calculations by
> observation. I don't know who MX is referring to.
>

The little "Famous physicists " pics he had on his jammies.

> Pure math research doesn't need anything but internal consistancy, but
> every worthwhile scientist is verifying by measurement, and the
> measurements are becoming exquisitely accurate.
>
> I wish I could be as predictive in my field as those in the hard
> sciences are in theirs.
>
>

What's the deal with infinitely dividing the time it takes for a quarter to
hit the floor anyway?

Actually, I might have more insight into that than most in that lab we like
to cal "the last sector"

Bertie

Bertie the Bunyip[_19_]

October 6th 07, 08:24 AM

Mxsmanic > wrote in
:

> Gatt writes:
>
>> I SWEAR to you guys, somebody sounding conspicuously like him was out
>> here within the last couple of months refuting Bournoulli and
>> referring to pressure under the wing, making plywood fly, etc.
>> Sounds awful familiar.
>
> It's entirely possible for an opinion to be shared by several people,
> even if that opinion is not shared by the president of the treehouse
> club.
>

If there was any doubt before...

Bertie

Bertie the Bunyip[_19_]

October 6th 07, 08:26 AM

Le Chaud Lapin > wrote in
ps.com:

> On Oct 5, 6:32 pm, wrote:
>> It's familiar because there are many out there who don't
>> understand or don't agree with the textbooks. Even among experts
>> there's disagreement. Every so often one of them makes an issue of
>> it. It's quite normal, especially if they don't use the Google Groups
>> Search function first to see what the previous arguments have been on
>> the subject on a particular newsgroup.
>
> I'd like to first note something since I am newly exposed to this
> field:
>
> In electrical engineering, we have our own set of fundamental
> principles. The "terminal" set of primitives governing electronics
> (electrostatics and electrodynamics) is Maxwells Equations
> http://en.wikipedia.org/wiki/Maxwell_equation. In EE, we have out
> own myths, like power lines causing brain cancer, but when they arise,
> the experts work hard to show indisputable evidence, verifiable,
> rigorous evidence to the contrary, to nip the non-sense in the bud.
> We do still have areas of disputes, like what causes shot noise in
> circuits [http://en.wikipedia.org/wiki/Shot_noise], but on the bread-
> and-butter basics, you won't find a college-leve textbook speaking
> untruth. So naturally I am extremely surprised to see this happening
> in aerodynamics. You are, after all, the rocket scientists. :)
> [i]
>> It annoys some of us because the same arguments are put forth
>> repeatedly and we can't figure out why some don't get it. But it's no
>> different than my classroom, in which every new batch of students
>> brings the same misunderstandings and doubts and arguments. We were
>> young once, too, and didn't believe much of what our teachers were
>> trying to tell us.
>
> Oh, I certainly don't believe what I wrote in the Jeppensen book. I
> don't believe what the 3 CFI's told me recently. I don't believe what
> my friends friend, the pilot, told me three years ago. And though I
> would be highly honored if I could meet him, I don't believe what Rod
> Machado, whom I think we would all agree is not exactly dumb nor a bad
> teacher, nor ignorant in the field, wrote. I don't believe it for two
> reasons:
>
> 1. It's obviously wrong if you read and interpret correctly what
> Bernoulli wrote.
> 2. NASA says it's wrong. From Jim Logajan:
> http://www.grc.nasa.gov/WWW/K-12/airplane/bernnew.html
>
>> Bernoulli said that moving air has a lower pressure than
>> static air. The air over the top of the wing is moving considerably
>> faster than that underneath, so it has lower pressure.
>
> People are going to yell and boo me for saying this, but after taking
> a nice long ride tonight on my motorcyle tonight, I thought the
> venturi/Bernoulli thing through, and I am 95% certain that that is not
> the reason the pressure is lower. In fact, I could probably provide an
> experiment showing you a situation where air is moving considerably
> faster on top than it is on the bottom, with much higher presure on
> the top. What is ironic is that Bernoulli would still be right, but
> the interpretation of Bernoulli would fall apart.
>
>> It's not
>> rarefaction; it's the increase in dynamic pressure (velocity) that
>> subtracts from static pressure, the same phenomenon that makes a
>> turbine engine work so well.
>
> Not to nit-pick, but dynamic pressure is p(t), where t is time, and
> velocity is d/dt R(t), where R is position vector, two totally
> different things.
>
>> Newton said that for every action there's an equal and
>> opposite reaction. If you look at the diagrams of airflow
>> here,http://www.av8n.com/how/htm/airfoils.html scrolling down to
>> Figure 3.2, you'll see that there's upwash ahead of the wing as well
>> as downwash behind it. the upwash is generated by the approaching low
>> pressure area above the wing. As the wing passes, the upwash is
>> converted to downwash; if this isn't Newton at work, I don't know
>> what is. Newton would be just another dead guy.
>
> Newton did say that. And I looked at that diagram very carefully.
> [Thanks for link] The upwash is not casued by an approaching low
> pressure. The upwash is caused by a gradient in pressure, going from
> high pressure at the leading ede, to low pressure, right above and
> slightly-back of the wing, due to rarefication of the wing in motion.
> The area above the rarefication is normal atmosphere that has a
> propensity to move toward the lower-pressure, rarefied air. The
> combination of that normal atmosphere air, combine with the high
> velocity of the molecules from the leading edge of the wing, results
> in the flow paths (streams) that you see. I haven't looked yet, but I
> imagine that there are aerodynamicists, all over the world, who, if
> not for appreciation of the hypothesis I am proposing here, have at
> least figured this out empircally, and are fretting day and night
> trying to find the optimal shape of the leading edge of the wing.
> They have two conflicting objectives:
>
> 1. Make the shape in such a way so as to minimize drag.
> 2. Make the shape in such a way so as to increase pressure to impart
> high velocity to air molecules moving up/backwards.
>
> I'll be the first to admit that i don't have the capacity to do so at
> this moment, but imagine that that one shape of the leading edge is
> not appropriate for all speeds of the aircraft. For a given set of
> context variables like density, temperature, pressure, angle-of-
> attack, airspeed, what-the-plane-was-doing-20-milliseconds-ago,
> turbulences...wind, etc...there is an optimal shape for that leading
> edge, depending on what you are trying to do. It would be quite wild
> if someone were to design a wing that could morph, dynamically by
> control of a computer, into an instaneously-optimal shape.
>
>> For the average PPL or CPL this should be sufficient. It's
>> true
>> enough, even if it doesn't give the detail that the physicist would
>> like. As I said, most pilots have other careers and interests and
>> they find that Newton and Bernoulli jibe with what they experience in
>> the air, so they're satisfied. Making textbooks thicker or filling
>> them with competing theories does nothing but confuse these people.
>
> I believe it should be possible to explain a venturi tube, Bernoulli's
> principle, and a decent part of why a wing has lift, in about 2-3
> pages of written text, with pictures, using no formulas, not even
> grade-school mathematics.
>
>> If a student wants to argue that the physics as presented are
>> all wrong he should do extensive research and publish a book on the
>> subject, not argue with pilots who have been trusting their soft pink
>> bodies to Bernoulli and Newton for decades.
>
> I definitely agree a paper should be written, and there should be an
> element of rigor, obviously lacking in my posts. :)
>
> However, I honestly think pilot's have been trusting neither Bernoulli
> nor Newton. They are dead. But they each left a legacy, which,
> according to the NASA links, have been misinterpreted and abused by
> countless theoritsts and educators in this field. So one could say
> that the pilots have been trusting these theorists and educators, but
> perhaps not even that is the case. I think what Ron hinted at is most-
> likely the case, that there is a phenomenon that would allow even a
> Neanderthal to achieve technical advancement:
>
> The Neanderthal starts with a contraption that works, and through much
> trial-and-error, finds better and better rendentions of that same
> contraption. Eventually, he will have something that works so well,
> that the question of "Why" would hardly need be asked. Naturally,
> theorists will tag along and try to explain with rigorous scientific
> principles what he has accomplished with only raw will of spirit, but
> the theory does not necessarily have to be right or complete get the
> thing in the air. Of course, the Wright Brothers were high-minded
> individuals, but I think you get the point.
>
> One might ask, "Well if that is the case, then what is the point of
> nit-picking with theory?"
>
> It is because a theory that correctly explains observed phenomenon
> generally opens up an entirely new world of order and efficiency.
>
> -Le Chaud Lapin-
>

Wanna make a bet about how long it takes you to get your licence?

Let's have a pool!

I got never!

Bertie
>

Dan Luke[_2_]

October 6th 07, 12:12 PM

"Bertie the Bunyip" wrote:

>
>> The physicists I know worry about confirming their calculations by
>> observation. I don't know who MX is referring to.
>>
>
> The little "Famous physicists " pics he had on his jammies.

Haw!

You're on a hot streak, Bertie.

--
Dan
T-182T at BFM

Matt Whiting

October 6th 07, 12:38 PM

Le Chaud Lapin wrote:

> In electrical engineering, we have our own set of fundamental
> principles. The "terminal" set of primitives governing electronics
> (electrostatics and electrodynamics) is Maxwells Equations
> http://en.wikipedia.org/wiki/Maxwell_equation. [Ironically, during
> his lifetime, Maxwell was also someone who was a leading expert on
> aerodynamics. The notions of gradients, the Laplacian, and scalar
> potentials have strong parallels in both fields.] In EE, we have out
> own myths, like power lines causing brain cancer, but when they arise,
> the experts work hard to show indisputable evidence, verifiable,
> rigorous evidence to the contrary, to nip the non-sense in the bud.
> We do still have areas of disputes, like what causes shot noise in
> circuits [http://en.wikipedia.org/wiki/Shot_noise], but on the bread-
> and-butter basics, you won't find a college-leve textbook speaking
> untruth. So naturally I am extremely surprised to see this happening
> in aerodynamics. You are, after all, the rocket scientists. :)

Really? Many books still can't agree on the definition of current.
Some say it is the movement of electrons and some say it is the movement
of positive charge and some say it us both. Which is the absolute
truth, Mr. Wizard?

Matt

Mxsmanic

October 6th 07, 01:09 PM

Le Chaud Lapin writes:

> In electrical engineering, we have our own set of fundamental
> principles. The "terminal" set of primitives governing electronics
> (electrostatics and electrodynamics) is Maxwells Equations
> http://en.wikipedia.org/wiki/Maxwell_equation. [Ironically, during
> his lifetime, Maxwell was also someone who was a leading expert on
> aerodynamics. The notions of gradients, the Laplacian, and scalar
> potentials have strong parallels in both fields.] In EE, we have out
> own myths, like power lines causing brain cancer, but when they arise,
> the experts work hard to show indisputable evidence, verifiable,
> rigorous evidence to the contrary, to nip the non-sense in the bud.
> We do still have areas of disputes, like what causes shot noise in
> circuits [http://en.wikipedia.org/wiki/Shot_noise], but on the bread-
> and-butter basics, you won't find a college-leve textbook speaking
> untruth. So naturally I am extremely surprised to see this happening
> in aerodynamics. You are, after all, the rocket scientists. :)

Perhaps you have seen EE from the inside and aerodynamics from the outside.
They may resemble each other far more than you realize. Remember how well
Tesla was received.

> 2. NASA says it's wrong. From Jim Logajan: http://www.grc.nasa.gov/WWW/K-12/airplane/bernnew.html

The question, though, is who exactly is "NASA"? The organization didn't write
the text (which, by the way, is an explanation for schoolkids); a human being
did. Is an individual human being as reliably correct as all of NASA? This
is another illustration of the dangers of credentialism.

> I'll be the first to admit that i don't have the capacity to do so at
> this moment, but imagine that that one shape of the leading edge is
> not appropriate for all speeds of the aircraft. For a given set of
> context variables like density, temperature, pressure, angle-of-
> attack, airspeed, what-the-plane-was-doing-20-milliseconds-ago,
> turbulences...wind, etc...there is an optimal shape for that leading
> edge, depending on what you are trying to do. It would be quite wild
> if someone were to design a wing that could morph, dynamically by
> control of a computer, into an instaneously-optimal shape.

Most of the adjustments in wing shape are intended to reduce drag or raise the
critical angle of attack. Otherwise a flat board would suffice. The very
common misconception is that the curve of the wing somehow is responsible for
the lift. It's not, of course. Only the angle of attack is responsible for
the lift.

The weird thing is that the intuitive impression one has of a wing's function
is essentially correct. It looks like something that would point air down as
it passes, and that's exactly what it does. Only the details of how it does
it are hard to figure out and understand. Fortunately, it works extremely
well even if one doesn't understand the details.

> It is because a theory that correctly explains observed phenomenon
> generally opens up an entirely new world of order and efficiency.

The real problem arises when you have a theory that seems to explain all the
observations you make and yet may still be incorrect.

Mxsmanic

October 6th 07, 01:10 PM

Bertie the Bunyip writes:

> Wanna make a bet about how long it takes you to get your licence?

None of this will influence the time required to get a license.

Mxsmanic

October 6th 07, 01:10 PM

Matt Whiting writes:

> Really? Many books still can't agree on the definition of current.
> Some say it is the movement of electrons and some say it is the movement
> of positive charge and some say it us both. Which is the absolute
> truth, Mr. Wizard?

The absolute truth is unknown, and the real proof of wizardry is the ability
to say "I don't know."

Dudley Henriques[_2_]

October 6th 07, 02:18 PM

Le Chaud Lapin wrote:
> On Oct 5, 6:32 pm, wrote:
>> It's familiar because there are many out there who don't
>> understand or don't agree with the textbooks. Even among experts
>> there's disagreement. Every so often one of them makes an issue of it.
>> It's quite normal, especially if they don't use the Google Groups
>> Search function first to see what the previous arguments have been on
>> the subject on a particular newsgroup.
>
> I'd like to first note something since I am newly exposed to this
> field:
>
> In electrical engineering, we have our own set of fundamental
> principles. The "terminal" set of primitives governing electronics
> (electrostatics and electrodynamics) is Maxwells Equations
> http://en.wikipedia.org/wiki/Maxwell_equation. In EE, we have out
> own myths, like power lines causing brain cancer, but when they arise,
> the experts work hard to show indisputable evidence, verifiable,
> rigorous evidence to the contrary, to nip the non-sense in the bud.
> We do still have areas of disputes, like what causes shot noise in
> circuits [http://en.wikipedia.org/wiki/Shot_noise], but on the bread-
> and-butter basics, you won't find a college-leve textbook speaking
> untruth. So naturally I am extremely surprised to see this happening
> in aerodynamics. You are, after all, the rocket scientists. :)
> [i]
>> It annoys some of us because the same arguments are put forth
>> repeatedly and we can't figure out why some don't get it. But it's no
>> different than my classroom, in which every new batch of students
>> brings the same misunderstandings and doubts and arguments. We were
>> young once, too, and didn't believe much of what our teachers were
>> trying to tell us.
>
> Oh, I certainly don't believe what I wrote in the Jeppensen book. I
> don't believe what the 3 CFI's told me recently. I don't believe what
> my friends friend, the pilot, told me three years ago. And though I
> would be highly honored if I could meet him, I don't believe what Rod
> Machado, whom I think we would all agree is not exactly dumb nor a bad
> teacher, nor ignorant in the field, wrote. I don't believe it for two
> reasons:
>
> 1. It's obviously wrong if you read and interpret correctly what
> Bernoulli wrote.
> 2. NASA says it's wrong. From Jim Logajan: http://www.grc.nasa.gov/WWW/K-12/airplane/bernnew.html
>
>> Bernoulli said that moving air has a lower pressure than
>> static air. The air over the top of the wing is moving considerably
>> faster than that underneath, so it has lower pressure.
>
> People are going to yell and boo me for saying this, but after taking
> a nice long ride tonight on my motorcyle tonight, I thought the
> venturi/Bernoulli thing through, and I am 95% certain that that is not
> the reason the pressure is lower. In fact, I could probably provide an
> experiment showing you a situation where air is moving considerably
> faster on top than it is on the bottom, with much higher presure on
> the top. What is ironic is that Bernoulli would still be right, but
> the interpretation of Bernoulli would fall apart.
>
>> It's not
>> rarefaction; it's the increase in dynamic pressure (velocity) that
>> subtracts from static pressure, the same phenomenon that makes a
>> turbine engine work so well.
>
> Not to nit-pick, but dynamic pressure is p(t), where t is time, and
> velocity is d/dt R(t), where R is position vector, two totally
> different things.
>
>> Newton said that for every action there's an equal and
>> opposite reaction. If you look at the diagrams of airflow here,http://www.av8n.com/how/htm/airfoils.html
>> scrolling down to Figure 3.2, you'll see that there's upwash ahead of
>> the wing as well as downwash behind it. the upwash is generated by the
>> approaching low pressure area above the wing. As the wing passes, the
>> upwash is converted to downwash; if this isn't Newton at work, I don't
>> know what is. Newton would be just another dead guy.
>
> Newton did say that. And I looked at that diagram very carefully.
> [Thanks for link] The upwash is not casued by an approaching low
> pressure. The upwash is caused by a gradient in pressure, going from
> high pressure at the leading ede, to low pressure, right above and
> slightly-back of the wing, due to rarefication of the wing in motion.
> The area above the rarefication is normal atmosphere that has a
> propensity to move toward the lower-pressure, rarefied air. The
> combination of that normal atmosphere air, combine with the high
> velocity of the molecules from the leading edge of the wing, results
> in the flow paths (streams) that you see. I haven't looked yet, but I
> imagine that there are aerodynamicists, all over the world, who, if
> not for appreciation of the hypothesis I am proposing here, have at
> least figured this out empircally, and are fretting day and night
> trying to find the optimal shape of the leading edge of the wing.
> They have two conflicting objectives:
>
> 1. Make the shape in such a way so as to minimize drag.
> 2. Make the shape in such a way so as to increase pressure to impart
> high velocity to air molecules moving up/backwards.
>
> I'll be the first to admit that i don't have the capacity to do so at
> this moment, but imagine that that one shape of the leading edge is
> not appropriate for all speeds of the aircraft. For a given set of
> context variables like density, temperature, pressure, angle-of-
> attack, airspeed, what-the-plane-was-doing-20-milliseconds-ago,
> turbulences...wind, etc...there is an optimal shape for that leading
> edge, depending on what you are trying to do. It would be quite wild
> if someone were to design a wing that could morph, dynamically by
> control of a computer, into an instaneously-optimal shape.
>
>> For the average PPL or CPL this should be sufficient. It's true
>> enough, even if it doesn't give the detail that the physicist would
>> like. As I said, most pilots have other careers and interests and they
>> find that Newton and Bernoulli jibe with what they experience in the
>> air, so they're satisfied. Making textbooks thicker or filling them
>> with competing theories does nothing but confuse these people.
>
> I believe it should be possible to explain a venturi tube, Bernoulli's
> principle, and a decent part of why a wing has lift, in about 2-3
> pages of written text, with pictures, using no formulas, not even
> grade-school mathematics.
>
>> If a student wants to argue that the physics as presented are
>> all wrong he should do extensive research and publish a book on the
>> subject, not argue with pilots who have been trusting their soft pink
>> bodies to Bernoulli and Newton for decades.
>
> I definitely agree a paper should be written, and there should be an
> element of rigor, obviously lacking in my posts. :)
>
> However, I honestly think pilot's have been trusting neither Bernoulli
> nor Newton. They are dead. But they each left a legacy, which,
> according to the NASA links, have been misinterpreted and abused by
> countless theoritsts and educators in this field. So one could say
> that the pilots have been trusting these theorists and educators, but
> perhaps not even that is the case. I think what Ron hinted at is most-
> likely the case, that there is a phenomenon that would allow even a
> Neanderthal to achieve technical advancement:
>
> The Neanderthal starts with a contraption that works, and through much
> trial-and-error, finds better and better rendentions of that same
> contraption. Eventually, he will have something that works so well,
> that the question of "Why" would hardly need be asked. Naturally,
> theorists will tag along and try to explain with rigorous scientific
> principles what he has accomplished with only raw will of spirit, but
> the theory does not necessarily have to be right or complete get the
> thing in the air. Of course, the Wright Brothers were high-minded
> individuals, but I think you get the point.
>
> One might ask, "Well if that is the case, then what is the point of
> nit-picking with theory?"
>
> It is because a theory that correctly explains observed phenomenon
> generally opens up an entirely new world of order and efficiency.
>
> -Le Chaud Lapin-
>

My initial reaction after reading this was sadness, as I hate to see
anyone die while attempting to fly an airplane, but after realizing that
you are probably not a student pilot at all, but a sockpuppet (and not a
very good one at that :-)) these fears won't be realized.
On that note, I'll turn you back to Bertie who seems to need no help
from me in "handling you" on these forums.
All the best of luck anyway........(just in case......so I'll feel
better for having asked you to stay as far away from an airplane as you
possibly can :-)
DH

--
Dudley Henriques

Tina

October 6th 07, 02:53 PM

Matt, come on, you're better than that. You have to know what you're
talking about re current flow is simply accepting one convention or
another. In either case (using a plus or a minus sign consistantly
when writing loop equations for example) the calculations and
observations match fairly well.

The hand waving about lift is equally funny: people are attaching
names to various theories, but the reality is the physics used in the
analysis of lift work well enough to predict performance. The 'wise
fools' will wave their hands and argue, those knowing what they are
doing will design airplanes.

muff528

October 6th 07, 03:36 PM

"Tina" > wrote in message
ps.com...
> Matt, come on, you're better than that. You have to know what you're
> talking about re current flow is simply accepting one convention or
> another. In either case (using a plus or a minus sign consistantly
> when writing loop equations for example) the calculations and
> observations match fairly well.
>
> The hand waving about lift is equally funny: people are attaching
> names to various theories, but the reality is the physics used in the
> analysis of lift work well enough to predict performance. The 'wise
> fools' will wave their hands and argue, those knowing what they are
> doing will design airplanes.

BADA BING!

(I'm a southerner so spelling or usage may or may not be correct)

Le Chaud Lapin

October 6th 07, 04:53 PM

On Oct 6, 6:38 am, Matt Whiting > wrote:
> Really? Many books still can't agree on the definition of current.
> Some say it is the movement of electrons and some say it is the movement
> of positive charge and some say it us both. Which is the absolute
> truth, Mr. Wizard?

The truth is that the electrons move, not the protons.

If you are referring to holes http://en.wikipedia.org/wiki/Electron_hole
and electrons in semiconductors http://en.wikipedia.org/wiki/Semiconductor
, where the descriptions of flow of charge through a semiconductor
lattice shows both positive and negative charge flow, in opposite
directions, in the present of an electrical field, the negative charge
being represented by electrons, the positive charge being represented
by holes.

Every book in electrical engineering is likely quite explicit in
telling students up front, (more like forming an agreement with the
students), that the holes are to be modeled as physical particles
because that it is mathematically equivalent to the true phenonmenon,
which is a void moving through the lattice, that, although there are
people who are quite capable of modeling the truth, which is based on
stochastics and energy-band http://en.wikipedia.org/wiki/Energy_band
theory, they will use the one that is simpler since the two models are
functionally equivalent. Note that any professor writing a book
claiming that holes are real particles would probably be barred from
teaching. In the world of electrical engineering, it would be like
saying that the Santa Claus really does exist, knowing that the
professors themselves created the figment of Santa Claus. I cannot
emphasize enough that there is no confusion whatsoever in the minds of
the students about what is actually going on inside the lattice.
There is no doubt in their minds that there are no such thing as
physical particles called holes moving through a lattice. There is no
doubt because professors conscientiously created this fiction, and
tells their students: "We all know that there are no hole
particles...but.." You will notice that the Wikpedia description of
holes uses the word 'conceptual' in the first sentence.

A related concept is something called phonons: http://en.wikipedia.org/wiki/Phonon
These are quantum mechanical pseudo-particles. Electrical engineers
and physicists know that they do not exist. They know because they
made them up, just like the made up the holes.

There is nothing wrong with doing this. In each case, there is no
untruth being spoken, because the scientists say up front: "We are
about to tell you something that is not really true. Just keep in
mind what the real truth is as we go along, please." This implies
that the EE students know the real truth, which they do, because those
same professors tell them that also. The aerodynamicists say: "We are
about to tell you something that is true.", and they say nothing more,
because they think that what they are about to say is not a
mathematically equivalent model of the truth, but truth itself.

Consider the case where one might do a systems problem to find the
voltage across a capacitorhttp://en.wikipedia.org/wiki/Capacitor, and
end up with something like...

V(t) = 12 * Integral(Delta(t)) + u(t)*e^-3t*e[jwt/(4*pi)]

j is the square root of negative one (-1)
w = angular frequency http://en.wikipedia.org/wiki/Angular_frequency
t = time u(t) is Heaviside step function http://en.wikipedia.org/wiki/Unit_step_function
Delta(t) is the Dirac-delta function http://en.wikipedia.org/wiki/Dirac_delta)

This voltage contains complex numbers sitting n an exponential. It
also contains a phenomenon that occurs so quick that is is
mathematically impossible to observe in time, yet its effect during
that brief moment is infinite. This is ridiculous. We know with
certainty that no such things exist in real-life. But that's ok,
because we made these things. Electrical engineers looking at this
will know immediately what the truth is, what the math represents.
What is odd is that one eventually reachs a point where no uneasiness
at all comes from moving between the real and the unreal. They are,
in an abstract sense, in separable.

Futhermore, concerning the point you made, if the above voltage V(t)
is positive, then by the formula for charge on a capacitor, Q=CV,
since C, the capacitance, is [ahemm....always positive...please, if
you are a EE reading this, please don't start up with me about general
impedance converters :)], the the charge is possitive, but we just
noted in the semiconductor example above that one does not find
positive charge running around in circuits because the are constrained
to the nuclei of atoms http://en.wikipedia.org/wiki/Atomic_nucleus
with their neutron buddies. This does not bother electrical engineers
because they see the formula and immediately see the image of what is
going on, the truth of physics as it occurs. Note that, if the
formula claims that there is positive charge on one plate of the
capacitor, there really is no positive charge "on the plate" so to
speak, but a depletion of negative charge, which is mathematically
eqivalent model of truth, just as there is no such thing as square-
root of negative number in real life, but if you use Euler's Formula
http://en.wikipedia.org/wiki/Euler's_formula, a Taylor expansion of
the formula about t http://en.wikipedia.org/wiki/Taylor_expansion, you
will see that the V(t) comes out to the nice sine waves that you would
see on an oscilloscopehttp://en.wikipedia.org/wiki/Oscilloscope .

Contrast this with what the aerodynamicists are doing. They are not
issuinig disclaimers saying, "this is not really what is happening, we
all know that, but let us pretend to make the math simpler for now".
They claim what they are illustrating *is* the truth.

-Le Chaud Lapin-

Le Chaud Lapin

October 6th 07, 06:06 PM

On Oct 6, 8:53 am, Tina > wrote:
> The hand waving about lift is equally funny: people are attaching
> names to various theories, but the reality is the physics used in the
> analysis of lift work well enough to predict performance. The 'wise
> fools' will wave their hands and argue, those knowing what they are
> doing will design airplanes.

This I definitely agree with. Even if aerodynamicists (is that even a
word) were so inept at physics that could not even calculate F=ma,
after so many iterations, they would still be able to make highly
refined airfoils simply because nature provides feedback to help one
distinguish between good designs and bad designs.

However, I must point out something I noted yesterday, that if you
have theory as well as the practice, the correct theory, there might
be opportunity to experience and entiely new realm of order and
efficiency.

I re-read the chapter on fluid mechanics in my physics book last night
and it says exactly what that NASA article refutes. Naturally, I was
bit perturbed - this physics book is same one used by some very good
universities. It also read in it a near verbatim explanation of
downwash as an example of Newton's law at work, that I found in the
Jeppesen book, the same explanation with is rigorously refuted by
NASA. I remember reading this chapter over and over a long time ago,
and "not getting it", and now I realize that it's because it is most
likely wrong.

In any case, there is something to be said for re-examining the
theory. There might be a bit of opportunity here.

I *think* I understand the physics behind reduced pressure above a
moving, appropriately shaped airfoil. *If* my suspicions are correct,
then it should be possible to make an entirely new type of aircraft,
where the mechanims to keep the aircraft flying are entirely different
from what they are today. I won't say too much now. I know no one
will consider it anyway. I'll just start fiddling, albeit slowly,
with my copy of SolidWorks that is coming in the mail soon.

I plan eventually to make a small-scale model. Hopefully, someday, I
might find someone involved in aerodynamics/flight to help make a
prototype.

-Le Chaud Lapin-

Bertie the Bunyip[_19_]

October 6th 07, 06:28 PM

Mxsmanic > wrote in
:

> Bertie the Bunyip writes:
>
>> Wanna make a bet about how long it takes you to get your licence?
>
> None of this will influence the time required to get a license.
>

No fair. you don't get to get into the pool. The horse never bets on
itself.

Bertie

Bertie the Bunyip[_19_]

October 6th 07, 06:30 PM

Mxsmanic > wrote in
:

> Le Chaud Lapin writes:
>
>> In electrical engineering, we have our own set of fundamental
>> principles. The "terminal" set of primitives governing electronics
>> (electrostatics and electrodynamics) is Maxwells Equations
>> http://en.wikipedia.org/wiki/Maxwell_equation. [Ironically, during
>> his lifetime, Maxwell was also someone who was a leading expert on
>> aerodynamics. The notions of gradients, the Laplacian, and scalar
>> potentials have strong parallels in both fields.] In EE, we have out
>> own myths, like power lines causing brain cancer, but when they
>> arise, the experts work hard to show indisputable evidence,
>> verifiable, rigorous evidence to the contrary, to nip the non-sense
>> in the bud. We do still have areas of disputes, like what causes shot
>> noise in circuits [http://en.wikipedia.org/wiki/Shot_noise], but on
>> the bread- and-butter basics, you won't find a college-leve textbook
>> speaking untruth. So naturally I am extremely surprised to see this
>> happening in aerodynamics. You are, after all, the rocket
>> scientists. :)
>
> Perhaps you have seen EE from the inside and aerodynamics from the
> outside. They may resemble each other far more than you realize.
> Remember how well Tesla was received.
>
>> 2. NASA says it's wrong. From Jim Logajan:
>> http://www.grc.nasa.gov/WWW/K-12/airplane/bernnew.html
>
> The question, though, is who exactly is "NASA"? The organization
> didn't write the text (which, by the way, is an explanation for
> schoolkids); a human being did. Is an individual human being as
> reliably correct as all of NASA? This is another illustration of the
> dangers of credentialism.
>
>> I'll be the first to admit that i don't have the capacity to do so at
>> this moment, but imagine that that one shape of the leading edge is
>> not appropriate for all speeds of the aircraft. For a given set of
>> context variables like density, temperature, pressure, angle-of-
>> attack, airspeed, what-the-plane-was-doing-20-milliseconds-ago,
>> turbulences...wind, etc...there is an optimal shape for that leading
>> edge, depending on what you are trying to do. It would be quite wild
>> if someone were to design a wing that could morph, dynamically by
>> control of a computer, into an instaneously-optimal shape.
>
> Most of the adjustments in wing shape are intended to reduce drag or
> raise the critical angle of attack. Otherwise a flat board would
> suffice.

Nope. Wrong, fjukktard. A chuck glider 777 is not going to make it to
Tokyo

Bertie

Matt Whiting

October 6th 07, 06:30 PM

Tina wrote:
> Matt, come on, you're better than that. You have to know what you're
> talking about re current flow is simply accepting one convention or
> another. In either case (using a plus or a minus sign consistantly
> when writing loop equations for example) the calculations and
> observations match fairly well.

I was simply making a point that there are different ways of looking at
the same thing. Much the same with lift and Bernoulli and Newton. Does
the difference in pressure between the top and bottom of the airfoil
cause the downward airflow behind the airfoil, or does the mechanical
deflection of the airflow cause the different in pressure between the
top and bottom of the wing? Inquiring minds want to know? :-)

Matt

Matt Whiting

October 6th 07, 06:36 PM

Le Chaud Lapin wrote:
> On Oct 6, 6:38 am, Matt Whiting > wrote:
>> Really? Many books still can't agree on the definition of current.
>> Some say it is the movement of electrons and some say it is the movement
>> of positive charge and some say it us both. Which is the absolute
>> truth, Mr. Wizard?
>
> The truth is that the electrons move, not the protons.

What about in the electrolyte inside a battery?

What about in a plasma?

What about in solid electrolytes?

> If you are referring to holes http://en.wikipedia.org/wiki/Electron_hole
> and electrons in semiconductors http://en.wikipedia.org/wiki/Semiconductor
> , where the descriptions of flow of charge through a semiconductor
> lattice shows both positive and negative charge flow, in opposite
> directions, in the present of an electrical field, the negative charge
> being represented by electrons, the positive charge being represented
> by holes.

I'm now pretty convinced that you are Mxmaniac and I need to update my
kill file.

[email protected]

October 6th 07, 06:45 PM

Le Chaud Lapin > wrote:
> On Oct 6, 6:38 am, Matt Whiting > wrote:
> > Really? Many books still can't agree on the definition of current.
> > Some say it is the movement of electrons and some say it is the movement
> > of positive charge and some say it us both. Which is the absolute
> > truth, Mr. Wizard?

> The truth is that the electrons move, not the protons.

You've fallen into the trap you are complaining about and providing
a simplistic answer that isn't true under all circumstances.

I can think of no mechanism to move protons in a solid, but they
move quite well in a vacuum.

Ever heard of a proton accelerator?

A current flow in a proton accelerator is a current flow of protons.

--
Jim Pennino

Remove .spam.sux to reply.

Bertie the Bunyip[_19_]

October 6th 07, 07:09 PM

Le Chaud Lapin > wrote in
ups.com:

> On Oct 6, 6:38 am, Matt Whiting > wrote:
>> Really? Many books still can't agree on the definition of current.
>> Some say it is the movement of electrons and some say it is the
>> movement of positive charge and some say it us both. Which is the
>> absolute truth, Mr. Wizard?
>
> The truth is that the electrons move, not the protons.
>
> If you are referring to holes
> http://en.wikipedia.org/wiki/Electron_hole and electrons in
> semiconductors http://en.wikipedia.org/wiki/Semiconductor , where the
> descriptions of flow of charge through a semiconductor lattice shows
> both positive and negative charge flow, in opposite directions, in the
> present of an electrical field, the negative charge being represented
> by electrons, the positive charge being represented by holes.
>
> Every book in electrical engineering is likely quite explicit in
> telling students up front, (more like forming an agreement with the
> students), that the holes are to be modeled as physical particles
> because that it is mathematically equivalent to the true phenonmenon,
> which is a void moving through the lattice, that, although there are
> people who are quite capable of modeling the truth, which is based on
> stochastics and energy-band http://en.wikipedia.org/wiki/Energy_band
> theory, they will use the one that is simpler since the two models are
> functionally equivalent. Note that any professor writing a book
> claiming that holes are real particles would probably be barred from
> teaching. In the world of electrical engineering, it would be like
> saying that the Santa Claus really does exist, knowing that the
> professors themselves created the figment of Santa Claus. I cannot
> emphasize enough that there is no confusion whatsoever in the minds of
> the students about what is actually going on inside the lattice.
> There is no doubt in their minds that there are no such thing as
> physical particles called holes moving through a lattice. There is no
> doubt because professors conscientiously created this fiction, and
> tells their students: "We all know that there are no hole
> particles...but.." You will notice that the Wikpedia description of
> holes uses the word 'conceptual' in the first sentence.
>
> A related concept is something called phonons:
> http://en.wikipedia.org/wiki/Phonon These are quantum mechanical
> pseudo-particles. Electrical engineers and physicists know that they
> do not exist. They know because they made them up, just like the made
> up the holes.
>
> There is nothing wrong with doing this. In each case, there is no
> untruth being spoken, because the scientists say up front: "We are
> about to tell you something that is not really true. Just keep in
> mind what the real truth is as we go along, please." This implies
> that the EE students know the real truth, which they do, because those
> same professors tell them that also. The aerodynamicists say: "We are
> about to tell you something that is true.", and they say nothing more,
> because they think that what they are about to say is not a
> mathematically equivalent model of the truth, but truth itself.
>
> Consider the case where one might do a systems problem to find the
> voltage across a capacitorhttp://en.wikipedia.org/wiki/Capacitor, and
> end up with something like...
>
> V(t) = 12 * Integral(Delta(t)) + u(t)*e^-3t*e[jwt/(4*pi)]
>
> j is the square root of negative one (-1)
> w = angular frequency http://en.wikipedia.org/wiki/Angular_frequency
> t = time u(t) is Heaviside step function
> http://en.wikipedia.org/wiki/Unit_step_function Delta(t) is the
> Dirac-delta function http://en.wikipedia.org/wiki/Dirac_delta)
>
> This voltage contains complex numbers sitting n an exponential. It
> also contains a phenomenon that occurs so quick that is is
> mathematically impossible to observe in time, yet its effect during
> that brief moment is infinite. This is ridiculous. We know with
> certainty that no such things exist in real-life. But that's ok,
> because we made these things. Electrical engineers looking at this
> will know immediately what the truth is, what the math represents.
> What is odd is that one eventually reachs a point where no uneasiness
> at all comes from moving between the real and the unreal. They are,
> in an abstract sense, in separable.
>
> Futhermore, concerning the point you made, if the above voltage V(t)
> is positive, then by the formula for charge on a capacitor, Q=CV,
> since C, the capacitance, is [ahemm....always positive...please, if
> you are a EE reading this, please don't start up with me about general
> impedance converters :)], the the charge is possitive, but we just
> noted in the semiconductor example above that one does not find
> positive charge running around in circuits because the are constrained
> to the nuclei of atoms http://en.wikipedia.org/wiki/Atomic_nucleus
> with their neutron buddies. This does not bother electrical engineers
> because they see the formula and immediately see the image of what is
> going on, the truth of physics as it occurs. Note that, if the
> formula claims that there is positive charge on one plate of the
> capacitor, there really is no positive charge "on the plate" so to
> speak, but a depletion of negative charge, which is mathematically
> eqivalent model of truth, just as there is no such thing as square-
> root of negative number in real life, but if you use Euler's Formula
> http://en.wikipedia.org/wiki/Euler's_formula, a Taylor expansion of
> the formula about t http://en.wikipedia.org/wiki/Taylor_expansion, you
> will see that the V(t) comes out to the nice sine waves that you would
> see on an oscilloscopehttp://en.wikipedia.org/wiki/Oscilloscope .
>
> Contrast this with what the aerodynamicists are doing. They are not
> issuinig disclaimers saying, "this is not really what is happening, we
> all know that, but let us pretend to make the math simpler for now".
> They claim what they are illustrating *is* the truth.
>

Yes, they are, they're just no ttelling you because you aren't designing
airplanes, fjukkwit.

Bertie>

Bertie the Bunyip[_19_]

October 6th 07, 07:10 PM

Le Chaud Lapin > wrote in
oups.com:

> On Oct 6, 8:53 am, Tina > wrote:
>> The hand waving about lift is equally funny: people are attaching
>> names to various theories, but the reality is the physics used in the
>> analysis of lift work well enough to predict performance. The 'wise
>> fools' will wave their hands and argue, those knowing what they are
>> doing will design airplanes.
>
> This I definitely agree with. Even if aerodynamicists (is that even a
> word) were so inept at physics that could not even calculate F=ma,
> after so many iterations, they would still be able to make highly
> refined airfoils simply because nature provides feedback to help one
> distinguish between good designs and bad designs.
>
> However, I must point out something I noted yesterday, that if you
> have theory as well as the practice, the correct theory, there might
> be opportunity to experience and entiely new realm of order and
> efficiency.
>
> I re-read the chapter on fluid mechanics in my physics book last night
> and it says exactly what that NASA article refutes. Naturally, I was
> bit perturbed - this physics book is same one used by some very good
> universities. It also read in it a near verbatim explanation of
> downwash as an example of Newton's law at work, that I found in the
> Jeppesen book, the same explanation with is rigorously refuted by
> NASA. I remember reading this chapter over and over a long time ago,
> and "not getting it", and now I realize that it's because it is most
> likely wrong.
>
> In any case, there is something to be said for re-examining the
> theory. There might be a bit of opportunity here.
>
> I *think* I understand the physics behind reduced pressure above a
> moving, appropriately shaped airfoil. *If* my suspicions are correct,
> then it should be possible to make an entirely new type of aircraft,
> where the mechanims to keep the aircraft flying are entirely different
> from what they are today. I won't say too much now. I know no one
> will consider it anyway. I'll just start fiddling, albeit slowly,
> with my copy of SolidWorks that is coming in the mail soon.
>
> I plan eventually to make a small-scale model. Hopefully, someday, I
> might find someone involved in aerodynamics/flight to help make a
> prototype.
>
> -Le Chaud Lapin-
>
>

You're an idiot

Bertie

Bertie the Bunyip[_19_]

October 6th 07, 07:10 PM

"Dan Luke" > wrote in news:13gercm9vnp7160
@news.supernews.com:

>
> "Bertie the Bunyip" wrote:
>
>>
>>> The physicists I know worry about confirming their calculations by
>>> observation. I don't know who MX is referring to.
>>>
>>
>> The little "Famous physicists " pics he had on his jammies.
>
> Haw!
>
> You're on a hot streak, Bertie.
>

Thanks, a good k00king always brings out the best!

Bertie

Mxsmanic

October 6th 07, 07:10 PM

Le Chaud Lapin writes:

> On Oct 6, 6:38 am, Matt Whiting > wrote:
> > Really? Many books still can't agree on the definition of current.
> > Some say it is the movement of electrons and some say it is the movement
> > of positive charge and some say it us both. Which is the absolute
> > truth, Mr. Wizard?
>
> The truth is that the electrons move, not the protons.

He said "movement of positive charge," not "movement of protons."

Le Chaud Lapin

October 6th 07, 07:15 PM

On Oct 6, 12:45 pm, wrote:
> Le Chaud Lapin > wrote:
>
> > On Oct 6, 6:38 am, Matt Whiting > wrote:
> > > Really? Many books still can't agree on the definition of current.
> > > Some say it is the movement of electrons and some say it is the movement
> > > of positive charge and some say it us both. Which is the absolute
> > > truth, Mr. Wizard?
> > The truth is that the electrons move, not the protons.
>
> You've fallen into the trap you are complaining about and providing
> a simplistic answer that isn't true under all circumstances.

Uh...no. The difference, as I pointed out with great redunancy in my
post, is that, in one case, there are two situations:

1. The truth, which the observers know.
2. The untruth, which the obsevers concoct to make the math simpler,
all the while keeping in mind what the truth is.

This is what happens with semiconductors.

In the other case, there is only one situation:

1. What the observers think is the truth.

In this latter case in aerodynamics, the observers do not say, "We all
know that this is not what is really happening..". Instead, they say,
"This is what's happening."

> I can think of no mechanism to move protons in a solid, but they
> move quite well in a vacuum.

Yes, I know. When I was tutoring electrodynamics, I used the problem
that I am sure you are familiar with, a proton, entering a uniform
magnetic field, and one must find the radius of its circular motion
based on the mass of the proton, the magnetic field intensity, etc.
This problem is so common, I decided to use a proton instead of an
electron to try to catch students who were cheating by simply copying
problems from previous years. The answer given by cheaters would have
the right radius but the wrong direction.

> Ever heard of a proton accelerator?

Yes, in fact, I had it as a disclaimer in my original post, just as I
had a disclaimer about a capacitor not being negative. [Note I said
that capacitors have positive capacitance, which is true, until you
start implementing virtual capacitors using general impedance
converters, which can make them negative, but then they are not real
capacitors, etc.] I took out counterexample about proton accelerators
because Wikipedia did not have an immediate link for the exact phrase
"proton accelerator", and the related links were bordering on quantum
physics, and I certainly don't want to open up a can of worms about
quantum physics in this group.

> A current flow in a proton accelerator is a current flow of protons.

Sure. But no one ever disputed that. Matt was implying that electrical
engineers/physicist cannot agree on what is actually going on, which
is not true. Most physicists who work with proton accelerators are
quite aware that that there is a proton moving under the influence of
the Lorentz force in an accelerator. No particle physicist ever
claims otherwise. Also, if you ask a bunch of electrical engineers,
"Does everyone that every know that there really is no such thing as a
hole, that it is in fact massive numbers of protons, entering an
exiting the energy band according to a stochastic model?" They would
say, "Yes, yes, we know! Now get on with your talk about these non-
existent holes."

Aerodynamics, today, is different. If you ask a bunch of aeronautical
engineers, "Does everyone know that the lift is due to the air on top
traveling faster than the air beneath, thus invoking Bernoulli's
Principle..yada yada....", Barry Schiff, and the person who wrote the
article at NASA, will say, "No. We do not agree with what you just
said."

-Le Chaud Lapin-

Bertie the Bunyip[_19_]

October 6th 07, 07:18 PM

Mxsmanic > wrote in
:

> Matt Whiting writes:
>
>> Really? Many books still can't agree on the definition of current.
>> Some say it is the movement of electrons and some say it is the
>> movement of positive charge and some say it us both. Which is the
>> absolute truth, Mr. Wizard?
>
> The absolute truth is unknown, and the real proof of wizardry is the
> ability to say "I don't know."
>

And the proof of your idiocy is that you can actualy say that with a
presumably straight face.

Bertie the Bunyip[_19_]

October 6th 07, 07:19 PM

Tina > wrote in news:1191678837.514394.4670
@r29g2000hsg.googlegroups.com:

> Matt, come on, you're better than that. You have to know what you're
> talking about re current flow is simply accepting one convention or
> another. In either case (using a plus or a minus sign consistantly
> when writing loop equations for example) the calculations and
> observations match fairly well.
>
> The hand waving about lift is equally funny: people are attaching
> names to various theories, but the reality is the physics used in the
> analysis of lift work well enough to predict performance. The 'wise
> fools' will wave their hands and argue, those knowing what they are
> doing will design airplanes.
>
>

Yep

Bertie

Bertie the Bunyip[_19_]

October 6th 07, 07:20 PM

Bertie the Bunyip[_19_]

October 6th 07, 07:31 PM

Le Chaud Lapin > wrote in
oups.com:

> On Oct 6, 12:45 pm, wrote:
>> Le Chaud Lapin > wrote:
>>
>> > On Oct 6, 6:38 am, Matt Whiting > wrote:
>> > > Really? Many books still can't agree on the definition of
>> > > current. Some say it is the movement of electrons and some say it
>> > > is the movement of positive charge and some say it us both.
>> > > Which is the absolute truth, Mr. Wizard?
>> > The truth is that the electrons move, not the protons.
>>
>> You've fallen into the trap you are complaining about and providing
>> a simplistic answer that isn't true under all circumstances.
>
> Uh...no. The difference, as I pointed out with great redunancy in my
> post, is that, in one case, there are two situations:
>
> 1. The truth, which the observers know.
> 2. The untruth, which the obsevers concoct to make the math simpler,
> all the while keeping in mind what the truth is.
>
> This is what happens with semiconductors.
>
> In the other case, there is only one situation:
>
> 1. What the observers think is the truth.
>
> In this latter case in aerodynamics, the observers do not say, "We all
> know that this is not what is really happening..". Instead, they say,
> "This is what's happening."
>
>> I can think of no mechanism to move protons in a solid, but they
>> move quite well in a vacuum.
>
> Yes, I know. When I was tutoring electrodynamics, I used the problem
> that I am sure you are familiar with, a proton, entering a uniform
> magnetic field, and one must find the radius of its circular motion
> based on the mass of the proton, the magnetic field intensity, etc.
> This problem is so common, I decided to use a proton instead of an
> electron to try to catch students who were cheating by simply copying
> problems from previous years. The answer given by cheaters would have
> the right radius but the wrong direction.
>
>> Ever heard of a proton accelerator?
>
> Yes, in fact, I had it as a disclaimer in my original post, just as I
> had a disclaimer about a capacitor not being negative. [Note I said
> that capacitors have positive capacitance, which is true, until you
> start implementing virtual capacitors using general impedance
> converters, which can make them negative, but then they are not real
> capacitors, etc.] I took out counterexample about proton accelerators
> because Wikipedia did not have an immediate link for the exact phrase
> "proton accelerator", and the related links were bordering on quantum
> physics, and I certainly don't want to open up a can of worms about
> quantum physics in this group.
>
>> A current flow in a proton accelerator is a current flow of protons.
>
> Sure. But no one ever disputed that. Matt was implying that electrical
> engineers/physicist cannot agree on what is actually going on, which
> is not true. Most physicists who work with proton accelerators are
> quite aware that that there is a proton moving under the influence of
> the Lorentz force in an accelerator. No particle physicist ever
> claims otherwise. Also, if you ask a bunch of electrical engineers,
> "Does everyone that every know that there really is no such thing as a
> hole, that it is in fact massive numbers of protons, entering an
> exiting the energy band according to a stochastic model?" They would
> say, "Yes, yes, we know! Now get on with your talk about these non-
> existent holes."
>
> Aerodynamics, today, is different. If you ask a bunch of aeronautical
> engineers, "Does everyone know that the lift is due to the air on top
> traveling faster than the air beneath, thus invoking Bernoulli's
> Principle..yada yada....",

You are a liar,. You've never asked anyone at Nasa anything.

Bertie

Bertie the Bunyip[_19_]

October 6th 07, 07:31 PM

Mxsmanic > wrote in
:

> Le Chaud Lapin writes:
>
>> On Oct 6, 6:38 am, Matt Whiting > wrote:
>> > Really? Many books still can't agree on the definition of current.
>> > Some say it is the movement of electrons and some say it is the
>> > movement of positive charge and some say it us both. Which is the
>> > absolute truth, Mr. Wizard?
>>
>> The truth is that the electrons move, not the protons.
>
> He said "movement of positive charge," not "movement of protons."
>

Yeh, right sockpuppet boi

Bertie

[email protected]

October 6th 07, 07:50 PM

On Oct 5, 6:27 pm, Mxsmanic > wrote:

> The angle of attack is the angle between the forward stagnation point and the
> trailing stagnation point. The points of intersection of the chord line with
> the airfoil surface are static, but the stagnation points can change, altering
> the angle of attack.
>
This has never been an accepted definition of angle of attack and
your creation of it has no credibility. You just create even more
confusion in your mind and in the minds of innocent truth-seekers
here.

> If the angle of attack is not positive, there is no lift. You cannot have
> lift at negative angles of attack because that is not symmetric.

So you don't believe NASA or NACA or anyone else that finds
lift at negative AOAs on some airfoils?

Dan

[email protected]

October 6th 07, 08:09 PM

On Oct 6, 12:14 am, Le Chaud Lapin > wrote:
> On Oct 5, 6:32 pm, wrote:

> People are going to yell and boo me for saying this, but after taking
> a nice long ride tonight on my motorcyle tonight, I thought the
> venturi/Bernoulli thing through, and I am 95% certain that that is not
> the reason the pressure is lower. In fact, I could probably provide an
> experiment showing you a situation where air is moving considerably
> faster on top than it is on the bottom, with much higher presure on
> the top. What is ironic is that Bernoulli would still be right, but
> the interpretation of Bernoulli would fall apart.

You keep talking about designing this experiment. Nothing
was ever accomplished with a lot of empty talk. When are you going to
start proving your theories? If you come up with something truly
revolutionary, we will all bow and scrape and tell our friends that we
had mistakenly defied a true master.

> > Newton said that for every action there's an equal and
> > opposite reaction. If you look at the diagrams of airflow here,http://www.av8n.com/how/htm/airfoils.html
> > scrolling down to Figure 3.2, you'll see that there's upwash ahead of
> > the wing as well as downwash behind it. the upwash is generated by the
> > approaching low pressure area above the wing. As the wing passes, the
> > upwash is converted to downwash; if this isn't Newton at work, I don't
> > know what is. Newton would be just another dead guy.
>
> Newton did say that. And I looked at that diagram very carefully.
> [Thanks for link] The upwash is not casued by an approaching low
> pressure. The upwash is caused by a gradient in pressure, going from
> high pressure at the leading ede, to low pressure, right above and
> slightly-back of the wing, due to rarefication of the wing in motion.

And that's not an effect of the approaching low pressure? In
any subsonic flow, the effect of any disturbance of the air travels
outward at the speed of sound. An approaching wing will affect air
molecule movement well ahead of it.

> The area above the rarefication is normal atmosphere that has a
> propensity to move toward the lower-pressure, rarefied air. The
> combination of that normal atmosphere air, combine with the high
> velocity of the molecules from the leading edge of the wing, results
> in the flow paths (streams) that you see. I haven't looked yet, but I
> imagine that there are aerodynamicists, all over the world, who, if
> not for appreciation of the hypothesis I am proposing here, have at
> least figured this out empircally, and are fretting day and night
> trying to find the optimal shape of the leading edge of the wing.
> They have two conflicting objectives:
>
> 1. Make the shape in such a way so as to minimize drag.
> 2. Make the shape in such a way so as to increase pressure to impart
> high velocity to air molecules moving up/backwards.
>
> I'll be the first to admit that i don't have the capacity to do so at
> this moment, but imagine that that one shape of the leading edge is
> not appropriate for all speeds of the aircraft.

Finally, two true statements: 1. You don't have the capacity, and 2.
The leading edge you see is not appropriate for all speeds of
aircraft. There are MANY different leading edges out there. I imagine
you haven't seen them.

>For a given set of
> context variables like density, temperature, pressure, angle-of-
> attack, airspeed, what-the-plane-was-doing-20-milliseconds-ago,
> turbulences...wind, etc...there is an optimal shape for that leading
> edge, depending on what you are trying to do. It would be quite wild
> if someone were to design a wing that could morph, dynamically by
> control of a computer, into an instaneously-optimal shape.

As if the engineers haven't been working on these wings for
years already. I have an article on my desk in front of me about
morphing helicopter blades to deal with retreating-blade stall. You
didn't really think you had a new idea, did you?
We already have variable-geometry wings. The fighter's swing-
wings, the airliner's triple-slotted flaps and its leading-edge slats
and flaps, on and on. All varying the airfoil for different speed
regimes and maneuvers. The problem with your instantaneous change is
one of maintaining structural integrity and strength and resistant to
flutter while keeping the weight low enough that it will fly. Maybe
you can solve that for us.

> I believe it should be possible to explain a venturi tube, Bernoulli's
> principle, and a decent part of why a wing has lift, in about 2-3
> pages of written text, with pictures, using no formulas, not even
> grade-school mathematics.

Commonly done in many texts. You just haven't read them yet.

> > If a student wants to argue that the physics as presented are
> > all wrong he should do extensive research and publish a book on the
> > subject, not argue with pilots who have been trusting their soft pink
> > bodies to Bernoulli and Newton for decades.
>
> I definitely agree a paper should be written, and there should be an
> element of rigor, obviously lacking in my posts. :)

Obviously.

There is a flow of goofy ideas through your head,
increasing in velocity, so that a vacuum is forming there.

Dan

george

October 6th 07, 08:17 PM

On Oct 6, 8:26 pm, Bertie the Bunyip > wrote:
> Le Chaud Lapin > wrote oups.com:
>
>
>
> > On Oct 5, 6:32 pm, wrote:
> >> It's familiar because there are many out there who don't
> >> understand or don't agree with the textbooks. Even among experts
> >> there's disagreement. Every so often one of them makes an issue of
> >> it. It's quite normal, especially if they don't use the Google Groups
> >> Search function first to see what the previous arguments have been on
> >> the subject on a particular newsgroup.
>
> > I'd like to first note something since I am newly exposed to this
> > field:
>
> > In electrical engineering, we have our own set of fundamental
> > principles. The "terminal" set of primitives governing electronics
> > (electrostatics and electrodynamics) is Maxwells Equations
> >http://en.wikipedia.org/wiki/Maxwell_equation. In EE, we have out
> > own myths, like power lines causing brain cancer, but when they arise,
> > the experts work hard to show indisputable evidence, verifiable,
> > rigorous evidence to the contrary, to nip the non-sense in the bud.
> > We do still have areas of disputes, like what causes shot noise in
> > circuits [http://en.wikipedia.org/wiki/Shot_noise], but on the bread-
> > and-butter basics, you won't find a college-leve textbook speaking
> > untruth. So naturally I am extremely surprised to see this happening
> > in aerodynamics. You are, after all, the rocket scientists. :)
>[i]
> >> It annoys some of us because the same arguments are put forth
> >> repeatedly and we can't figure out why some don't get it. But it's no
> >> different than my classroom, in which every new batch of students
> >> brings the same misunderstandings and doubts and arguments. We were
> >> young once, too, and didn't believe much of what our teachers were
> >> trying to tell us.
>
> > Oh, I certainly don't believe what I wrote in the Jeppensen book. I
> > don't believe what the 3 CFI's told me recently. I don't believe what
> > my friends friend, the pilot, told me three years ago. And though I
> > would be highly honored if I could meet him, I don't believe what Rod
> > Machado, whom I think we would all agree is not exactly dumb nor a bad
> > teacher, nor ignorant in the field, wrote. I don't believe it for two
> > reasons:
>
> > 1. It's obviously wrong if you read and interpret correctly what
> > Bernoulli wrote.
> > 2. NASA says it's wrong. From Jim Logajan:
> >http://www.grc.nasa.gov/WWW/K-12/airplane/bernnew.html
>
> >> Bernoulli said that moving air has a lower pressure than
> >> static air. The air over the top of the wing is moving considerably
> >> faster than that underneath, so it has lower pressure.
>
> > People are going to yell and boo me for saying this, but after taking
> > a nice long ride tonight on my motorcyle tonight, I thought the
> > venturi/Bernoulli thing through, and I am 95% certain that that is not
> > the reason the pressure is lower. In fact, I could probably provide an
> > experiment showing you a situation where air is moving considerably
> > faster on top than it is on the bottom, with much higher presure on
> > the top. What is ironic is that Bernoulli would still be right, but
> > the interpretation of Bernoulli would fall apart.
>
> >> It's not
> >> rarefaction; it's the increase in dynamic pressure (velocity) that
> >> subtracts from static pressure, the same phenomenon that makes a
> >> turbine engine work so well.
>
> > Not to nit-pick, but dynamic pressure is p(t), where t is time, and
> > velocity is d/dt R(t), where R is position vector, two totally
> > different things.
>
> >> Newton said that for every action there's an equal and
> >> opposite reaction. If you look at the diagrams of airflow
> >> here,http://www.av8n.com/how/htm/airfoils.htmlscrolling down to
> >> Figure 3.2, you'll see that there's upwash ahead of the wing as well
> >> as downwash behind it. the upwash is generated by the approaching low
> >> pressure area above the wing. As the wing passes, the upwash is
> >> converted to downwash; if this isn't Newton at work, I don't know
> >> what is. Newton would be just another dead guy.
>
> > Newton did say that. And I looked at that diagram very carefully.
> > [Thanks for link] The upwash is not casued by an approaching low
> > pressure. The upwash is caused by a gradient in pressure, going from
> > high pressure at the leading ede, to low pressure, right above and
> > slightly-back of the wing, due to rarefication of the wing in motion.
> > The area above the rarefication is normal atmosphere that has a
> > propensity to move toward the lower-pressure, rarefied air. The
> > combination of that normal atmosphere air, combine with the high
> > velocity of the molecules from the leading edge of the wing, results
> > in the flow paths (streams) that you see. I haven't looked yet, but I
> > imagine that there are aerodynamicists, all over the world, who, if
> > not for appreciation of the hypothesis I am proposing here, have at
> > least figured this out empircally, and are fretting day and night
> > trying to find the optimal shape of the leading edge of the wing.
> > They have two conflicting objectives:
>
> > 1. Make the shape in such a way so as to minimize drag.
> > 2. Make the shape in such a way so as to increase pressure to impart
> > high velocity to air molecules moving up/backwards.
>
> > I'll be the first to admit that i don't have the capacity to do so at
> > this moment, but imagine that that one shape of the leading edge is
> > not appropriate for all speeds of the aircraft. For a given set of
> > context variables like density, temperature, pressure, angle-of-
> > attack, airspeed, what-the-plane-was-doing-20-milliseconds-ago,
> > turbulences...wind, etc...there is an optimal shape for that leading
> > edge, depending on what you are trying to do. It would be quite wild
> > if someone were to design a wing that could morph, dynamically by
> > control of a computer, into an instaneously-optimal shape.
>
> >> For the average PPL or CPL this should be sufficient. It's
> >> true
> >> enough, even if it doesn't give the detail that the physicist would
> >> like. As I said, most pilots have other careers and interests and
> >> they find that Newton and Bernoulli jibe with what they experience in
> >> the air, so they're satisfied. Making textbooks thicker or filling
> >> them with competing theories does nothing but confuse these people.
>
> > I believe it should be possible to explain a venturi tube, Bernoulli's
> > principle, and a decent part of why a wing has lift, in about 2-3
> > pages of written text, with pictures, using no formulas, not even
> > grade-school mathematics.
>
> >> If a student wants to argue that the physics as presented are
> >> all wrong he should do extensive research and publish a book on the
> >> subject, not argue with pilots who have been trusting their soft pink
> >> bodies to Bernoulli and Newton for decades.
>
> > I definitely agree a paper should be written, and there should be an
> > element of rigor, obviously lacking in my posts. :)
>
> > However, I honestly think pilot's have been trusting neither Bernoulli
> > nor Newton. They are dead. But they each left a legacy, which,
> > according to the NASA links, have been misinterpreted and abused by
> > countless theoritsts and educators in this field. So one could say
> > that the pilots have been trusting these theorists and educators, but
> > perhaps not even that is the case. I think what Ron hinted at is most-
> > likely the case, that there is a phenomenon that would allow even a
> > Neanderthal to achieve technical advancement:
>
> > The Neanderthal starts with a contraption that works, and through much
> > trial-and-error, finds better and better rendentions of that same
> > contraption. Eventually, he will have something that works so well,
> > that the question of "Why" would hardly need be asked. Naturally,
> > theorists will tag along and try to explain with rigorous scientific
> > principles what he has accomplished with only raw will of spirit, but
> > the theory does not necessarily have to be right or complete get the
> > thing in the air. Of course, the Wright Brothers were high-minded
> > individuals, but I think you get the point.
>
> > One might ask, "Well if that is the case, then what is the point of
> > nit-picking with theory?"
>
> > It is because a theory that correctly explains observed phenomenon
> > generally opens up an entirely new world of order and efficiency.
>
> > -Le Chaud Lapin-
>
> Wanna make a bet about how long it takes you to get your licence?
>
> Let's have a pool!
>
> I got never!
>
90 hours to solo

Bertie the Bunyip[_19_]

October 6th 07, 08:28 PM

george > wrote in
ps.com:

> On Oct 6, 8:26 pm, Bertie the Bunyip > wrote:
>> Le Chaud Lapin > wrote
>> oups.com:
>>
>>
>>
>> > On Oct 5, 6:32 pm, wrote:
>> >> It's familiar because there are many out there who don't
>> >> understand or don't agree with the textbooks. Even among experts
>> >> there's disagreement. Every so often one of them makes an issue of
>> >> it. It's quite normal, especially if they don't use the Google
>> >> Groups Search function first to see what the previous arguments
>> >> have been on the subject on a particular newsgroup.
>>
>> > I'd like to first note something since I am newly exposed to this
>> > field:
>>
>> > In electrical engineering, we have our own set of fundamental
>> > principles. The "terminal" set of primitives governing electronics
>> > (electrostatics and electrodynamics) is Maxwells Equations
>> >http://en.wikipedia.org/wiki/Maxwell_equation. [Ironically, during
>> > his lifetime, Maxwell was also someone who was a leading expert on
>> > aerodynamics. The notions of gradients, the Laplacian, and scalar
>> > potentials have strong parallels in both fields.] In EE, we have
>> > out own myths, like power lines causing brain cancer, but when they
>> > arise, the experts work hard to show indisputable evidence,
>> > verifiable, rigorous evidence to the contrary, to nip the non-sense
>> > in the bud. We do still have areas of disputes, like what causes
>> > shot noise in circuits [http://en.wikipedia.org/wiki/Shot_noise],
>> > but on the bread- and-butter basics, you won't find a college-leve
>> > textbook speaking untruth. So naturally I am extremely surprised to
>> > see this happening in aerodynamics. You are, after all, the rocket
>> > scientists. :)
>>
>> >> It annoys some of us because the same arguments are put
>> >> forth
>> >> repeatedly and we can't figure out why some don't get it. But it's
>> >> no different than my classroom, in which every new batch of
>> >> students brings the same misunderstandings and doubts and
>> >> arguments. We were young once, too, and didn't believe much of
>> >> what our teachers were trying to tell us.
>>
>> > Oh, I certainly don't believe what I wrote in the Jeppensen book.
>> > I don't believe what the 3 CFI's told me recently. I don't believe
>> > what my friends friend, the pilot, told me three years ago. And
>> > though I would be highly honored if I could meet him, I don't
>> > believe what Rod Machado, whom I think we would all agree is not
>> > exactly dumb nor a bad teacher, nor ignorant in the field, wrote.
>> > I don't believe it for two reasons:
>>
>> > 1. It's obviously wrong if you read and interpret correctly what
>> > Bernoulli wrote.
>> > 2. NASA says it's wrong. From Jim Logajan:
>> >http://www.grc.nasa.gov/WWW/K-12/airplane/bernnew.html
>>
>> >> Bernoulli said that moving air has a lower pressure than
>> >> static air. The air over the top of the wing is moving
>> >> considerably faster than that underneath, so it has lower
>> >> pressure.
>>
>> > People are going to yell and boo me for saying this, but after
>> > taking a nice long ride tonight on my motorcyle tonight, I thought
>> > the venturi/Bernoulli thing through, and I am 95% certain that that
>> > is not the reason the pressure is lower. In fact, I could probably
>> > provide an experiment showing you a situation where air is moving
>> > considerably faster on top than it is on the bottom, with much
>> > higher presure on the top. What is ironic is that Bernoulli would
>> > still be right, but the interpretation of Bernoulli would fall
>> > apart.
>>
>> >> It's not
>> >> rarefaction; it's the increase in dynamic pressure (velocity) that
>> >> subtracts from static pressure, the same phenomenon that makes a
>> >> turbine engine work so well.
>>
>> > Not to nit-pick, but dynamic pressure is p(t), where t is time, and
>> > velocity is d/dt R(t), where R is position vector, two totally
>> > different things.
>>
>> >> Newton said that for every action there's an equal and
>> >> opposite reaction. If you look at the diagrams of airflow
>> >> here,http://www.av8n.com/how/htm/airfoils.htmlscrolling down to
>> >> Figure 3.2, you'll see that there's upwash ahead of the wing as
>> >> well as downwash behind it. the upwash is generated by the
>> >> approaching low pressure area above the wing. As the wing passes,
>> >> the upwash is converted to downwash; if this isn't Newton at work,
>> >> I don't know what is. Newton would be just another dead guy.
>>
>> > Newton did say that. And I looked at that diagram very carefully.
>> > [Thanks for link] The upwash is not casued by an approaching low
>> > pressure. The upwash is caused by a gradient in pressure, going
>> > from high pressure at the leading ede, to low pressure, right above
>> > and slightly-back of the wing, due to rarefication of the wing in
>> > motion. The area above the rarefication is normal atmosphere that
>> > has a propensity to move toward the lower-pressure, rarefied air.
>> > The combination of that normal atmosphere air, combine with the
>> > high velocity of the molecules from the leading edge of the wing,
>> > results in the flow paths (streams) that you see. I haven't looked
>> > yet, but I imagine that there are aerodynamicists, all over the
>> > world, who, if not for appreciation of the hypothesis I am
>> > proposing here, have at least figured this out empircally, and are
>> > fretting day and night trying to find the optimal shape of the
>> > leading edge of the wing. They have two conflicting objectives:
>>
>> > 1. Make the shape in such a way so as to minimize drag.
>> > 2. Make the shape in such a way so as to increase pressure to
>> > impart high velocity to air molecules moving up/backwards.
>>
>> > I'll be the first to admit that i don't have the capacity to do so
>> > at this moment, but imagine that that one shape of the leading edge
>> > is not appropriate for all speeds of the aircraft. For a given set
>> > of context variables like density, temperature, pressure, angle-of-
>> > attack, airspeed, what-the-plane-was-doing-20-milliseconds-ago,
>> > turbulences...wind, etc...there is an optimal shape for that
>> > leading edge, depending on what you are trying to do. It would be
>> > quite wild if someone were to design a wing that could morph,
>> > dynamically by control of a computer, into an instaneously-optimal
>> > shape.
>>
>> >> For the average PPL or CPL this should be sufficient. It's
>> >> true
>> >> enough, even if it doesn't give the detail that the physicist
>> >> would like. As I said, most pilots have other careers and
>> >> interests and they find that Newton and Bernoulli jibe with what
>> >> they experience in the air, so they're satisfied. Making textbooks
>> >> thicker or filling them with competing theories does nothing but
>> >> confuse these people.
>>
>> > I believe it should be possible to explain a venturi tube,
>> > Bernoulli's principle, and a decent part of why a wing has lift, in
>> > about 2-3 pages of written text, with pictures, using no formulas,
>> > not even grade-school mathematics.
>>
>> >> If a student wants to argue that the physics as presented
>> >> are
>> >> all wrong he should do extensive research and publish a book on
>> >> the subject, not argue with pilots who have been trusting their
>> >> soft pink bodies to Bernoulli and Newton for decades.
>>
>> > I definitely agree a paper should be written, and there should be
>> > an element of rigor, obviously lacking in my posts. :)
>>
>> > However, I honestly think pilot's have been trusting neither
>> > Bernoulli nor Newton. They are dead. But they each left a legacy,
>> > which, according to the NASA links, have been misinterpreted and
>> > abused by countless theoritsts and educators in this field. So one
>> > could say that the pilots have been trusting these theorists and
>> > educators, but perhaps not even that is the case. I think what Ron
>> > hinted at is most- likely the case, that there is a phenomenon that
>> > would allow even a Neanderthal to achieve technical advancement:
>>
>> > The Neanderthal starts with a contraption that works, and through
>> > much trial-and-error, finds better and better rendentions of that
>> > same contraption. Eventually, he will have something that works so
>> > well, that the question of "Why" would hardly need be asked.
>> > Naturally, theorists will tag along and try to explain with
>> > rigorous scientific principles what he has accomplished with only
>> > raw will of spirit, but the theory does not necessarily have to be
>> > right or complete get the thing in the air. Of course, the Wright
>> > Brothers were high-minded individuals, but I think you get the
>> > point.
>>
>> > One might ask, "Well if that is the case, then what is the point of
>> > nit-picking with theory?"
>>
>> > It is because a theory that correctly explains observed phenomenon
>> > generally opens up an entirely new world of order and efficiency.
>>
>> > -Le Chaud Lapin-
>>
>> Wanna make a bet about how long it takes you to get your licence?
>>
>> Let's have a pool!
>>
>> I got never!
>>
> 90 hours to solo
>
>

A control-line model

Bertie

Bertie the Bunyip[_19_]

October 6th 07, 08:29 PM

wrote in
oups.com:

> On Oct 6, 12:14 am, Le Chaud Lapin > wrote:
>> On Oct 5, 6:32 pm, wrote:
>
>> People are going to yell and boo me for saying this, but after taking
>> a nice long ride tonight on my motorcyle tonight, I thought the
>> venturi/Bernoulli thing through, and I am 95% certain that that is
>> not the reason the pressure is lower. In fact, I could probably
>> provide an experiment showing you a situation where air is moving
>> considerably faster on top than it is on the bottom, with much higher
>> presure on the top. What is ironic is that Bernoulli would still be
>> right, but the interpretation of Bernoulli would fall apart.
>
> You keep talking about designing this experiment. Nothing
> was ever accomplished with a lot of empty talk. When are you going to
> start proving your theories? If you come up with something truly
> revolutionary, we will all bow and scrape and tell our friends that we
> had mistakenly defied a true master.
>
>
>> > Newton said that for every action there's an equal and
>> > opposite reaction. If you look at the diagrams of airflow
>> > here,http://www.av8n.com/how/htm/airfoils.html scrolling down to
>> > Figure 3.2, you'll see that there's upwash ahead of the wing as
>> > well as downwash behind it. the upwash is generated by the
>> > approaching low pressure area above the wing. As the wing passes,
>> > the upwash is converted to downwash; if this isn't Newton at work,
>> > I don't know what is. Newton would be just another dead guy.
>>
>> Newton did say that. And I looked at that diagram very carefully.
>> [Thanks for link] The upwash is not casued by an approaching low
>> pressure. The upwash is caused by a gradient in pressure, going from
>> high pressure at the leading ede, to low pressure, right above and
>> slightly-back of the wing, due to rarefication of the wing in motion.
>
> And that's not an effect of the approaching low pressure? In
> any subsonic flow, the effect of any disturbance of the air travels
> outward at the speed of sound. An approaching wing will affect air
> molecule movement well ahead of it.
>
>> The area above the rarefication is normal atmosphere that has a
>> propensity to move toward the lower-pressure, rarefied air. The
>> combination of that normal atmosphere air, combine with the high
>> velocity of the molecules from the leading edge of the wing, results
>> in the flow paths (streams) that you see. I haven't looked yet, but
>> I imagine that there are aerodynamicists, all over the world, who, if
>> not for appreciation of the hypothesis I am proposing here, have at
>> least figured this out empircally, and are fretting day and night
>> trying to find the optimal shape of the leading edge of the wing.
>> They have two conflicting objectives:
>>
>> 1. Make the shape in such a way so as to minimize drag.
>> 2. Make the shape in such a way so as to increase pressure to impart
>> high velocity to air molecules moving up/backwards.
>>
>> I'll be the first to admit that i don't have the capacity to do so at
>> this moment, but imagine that that one shape of the leading edge is
>> not appropriate for all speeds of the aircraft.
>
> Finally, two true statements: 1. You don't have the capacity, and 2.
> The leading edge you see is not appropriate for all speeds of
> aircraft. There are MANY different leading edges out there. I imagine
> you haven't seen them.
>
>
>>For a given set of
>> context variables like density, temperature, pressure, angle-of-
>> attack, airspeed, what-the-plane-was-doing-20-milliseconds-ago,
>> turbulences...wind, etc...there is an optimal shape for that leading
>> edge, depending on what you are trying to do. It would be quite wild
>> if someone were to design a wing that could morph, dynamically by
>> control of a computer, into an instaneously-optimal shape.
>
> As if the engineers haven't been working on these wings for
> years already. I have an article on my desk in front of me about
> morphing helicopter blades to deal with retreating-blade stall. You
> didn't really think you had a new idea, did you?
> We already have variable-geometry wings. The fighter's swing-
> wings, the airliner's triple-slotted flaps and its leading-edge slats
> and flaps, on and on. All varying the airfoil for different speed
> regimes and maneuvers. The problem with your instantaneous change is
> one of maintaining structural integrity and strength and resistant to
> flutter while keeping the weight low enough that it will fly. Maybe
> you can solve that for us.
>
>
>> I believe it should be possible to explain a venturi tube,
>> Bernoulli's principle, and a decent part of why a wing has lift, in
>> about 2-3 pages of written text, with pictures, using no formulas,
>> not even grade-school mathematics.
>
> Commonly done in many texts. You just haven't read them yet.
>
>> > If a student wants to argue that the physics as presented
>> > are
>> > all wrong he should do extensive research and publish a book on the
>> > subject, not argue with pilots who have been trusting their soft
>> > pink bodies to Bernoulli and Newton for decades.
>>
>> I definitely agree a paper should be written, and there should be an
>> element of rigor, obviously lacking in my posts. :)
>
> Obviously.
>
> There is a flow of goofy ideas through your head,
> increasing in velocity, so that a vacuum is forming there.
>

So, ironically, he has probven Bernoulli after all.

Bertie

Le Chaud Lapin

October 6th 07, 08:32 PM

On Oct 6, 2:09 pm, wrote:
> > I believe it should be possible to explain a venturi tube, Bernoulli's
> > principle, and a decent part of why a wing has lift, in about 2-3
> > pages of written text, with pictures, using no formulas, not even
> > grade-school mathematics.
>
> Commonly done in many texts. You just haven't read them yet.

Which texts are those?

I have read some texts:

1. Jeppesen got it wrong.
2. Rod Machado got it wrong.
3. That link that with the funny color lines that was posted in this
thread got it wrong.
4. If you do search in Google for "Bernoulli" + "faster" + wing +
lift, you will see 1000's of pages that got it wrong.

Plus I watched 3 CFI's at my ground school, the one I paid money to
teach me the theory of flying, get it wrong at the whiteboard.

And of course, if the NASA paper is true, then there are even people
in this group who got it wrong.

Until 3 days ago, the number of people who had gotten (partially)
right was 1. The number of stories I had heard from people who got it
wrong was probably about 60-70.

After reading the link that Jim Logajan posted, the number of people
who are saying it's one way is 2. The number of people who are saying
it is the exact opposite is still 60-70.

Which textbooks would you believe if you had read 1 saying one thing,
and more than 10 others saying the exact opposite?

-Le Chaud Lapin-

Bertie the Bunyip[_19_]

October 6th 07, 08:46 PM

Le Chaud Lapin > wrote in
ps.com:

> On Oct 6, 2:09 pm, wrote:
>> > I believe it should be possible to explain a venturi tube,
Bernoulli's
>> > principle, and a decent part of why a wing has lift, in about 2-3
>> > pages of written text, with pictures, using no formulas, not even
>> > grade-school mathematics.
>>
>> Commonly done in many texts. You just haven't read them yet.
>
> Which texts are those?
>
> I have read some texts:
>
> 1. Jeppesen got it wrong.

No they didn't

> 2. Rod Machado got it wrong.

Don't know who he is but if you thnk he's wrong he can't be.

> 3. That link that with the funny color lines that was posted in this
> thread got it wrong.

Nope.

> 4. If you do search in Google for "Bernoulli" + "faster" + wing +
> lift, you will see 1000's of pages that got it wrong.

Nope.

>
> Plus I watched 3 CFI's at my ground school, the one I paid money to
> teach me the theory of flying, get it wrong at the whiteboard.
>

There's too many things wrong with this sentence to even start on.

> And of course, if the NASA paper is true, then there are even people
> in this group who got it wrong.

Well, you did , as botht yourself and your sockpuppet.

>
> Until 3 days ago, the number of people who had gotten (partially)
> right was 1.

Oha, and who was that?

Bertie
>

[email protected]

October 6th 07, 08:51 PM

On Oct 6, 1:32 pm, Le Chaud Lapin > wrote:
> On Oct 6, 2:09 pm, wrote:
>
> > > I believe it should be possible to explain a venturi tube, Bernoulli's
> > > principle, and a decent part of why a wing has lift, in about 2-3
> > > pages of written text, with pictures, using no formulas, not even
> > > grade-school mathematics.
>
> > Commonly done in many texts. You just haven't read them yet.
>
> Which texts are those?
>
> I have read some texts:
>
> 1. Jeppesen got it wrong.
> 2. Rod Machado got it wrong.
> 3. That link that with the funny color lines that was posted in this
> thread got it wrong.
> 4. If you do search in Google for "Bernoulli" + "faster" + wing +
> lift, you will see 1000's of pages that got it wrong.

All wrong, according to you. There's no point pointing out
any others. They'll be wrong, too.

> Plus I watched 3 CFI's at my ground school, the one I paid money to
> teach me the theory of flying, get it wrong at the whiteboard.

Rather common, distressingly. However, he may have had it
right; you have just determined that EVERYONE but you is wrong.

> And of course, if the NASA paper is true, then there are even people
> in this group who got it wrong.
>
> Until 3 days ago, the number of people who had gotten (partially)
> right was 1. The number of stories I had heard from people who got it
> wrong was probably about 60-70.
>
> After reading the link that Jim Logajan posted, the number of people
> who are saying it's one way is 2. The number of people who are saying
> it is the exact opposite is still 60-70.
>
> Which textbooks would you believe if you had read 1 saying one thing,
> and more than 10 others saying the exact opposite?
>
Does truth in physics depend on a democratic vote?

Dan

Le Chaud Lapin

October 6th 07, 08:57 PM

On Oct 6, 2:51 pm, wrote:
> On Oct 6, 1:32 pm, Le Chaud Lapin > wrote:

> > I have read some texts:
>
> > 1. Jeppesen got it wrong.
> > 2. Rod Machado got it wrong.
> > 3. That link that with the funny color lines that was posted in this
> > thread got it wrong.
> > 4. If you do search in Google for "Bernoulli" + "faster" + wing +
> > lift, you will see 1000's of pages that got it wrong.
>
> All wrong, according to you. There's no point pointing out
> any others. They'll be wrong, too.
>
> > Plus I watched 3 CFI's at my ground school, the one I paid money to
> > teach me the theory of flying, get it wrong at the whiteboard.
>
> Rather common, distressingly. However, he may have had it
> right; you have just determined that EVERYONE but you is wrong.

It wasn't just one. It was 3. My instructor, plus 2 others. They said
the thing that the NASA paper is calling "a myth". Who is right? The
NASA author or the CFI's?

> > And of course, if the NASA paper is true, then there are even people
> > in this group who got it wrong.
>
> > Until 3 days ago, the number of people who had gotten (partially)
> > right was 1. The number of stories I had heard from people who got it
> > wrong was probably about 60-70.
>
> > After reading the link that Jim Logajan posted, the number of people
> > who are saying it's one way is 2. The number of people who are saying
> > it is the exact opposite is still 60-70.
>
> > Which textbooks would you believe if you had read 1 saying one thing,
> > and more than 10 others saying the exact opposite?
>
> Does truth in physics depend on a democratic vote?

That's what I am asking...

After reading 60-70 that says one thing, and seeing 2 others that says
the exact opposite, and it just happen to be that the 2 are the ones
that you personally agree with, which would you believe? The 60-70?
The 2? Flip a coin?

-Le Chaud Lapin-

Matt Whiting

October 6th 07, 09:41 PM

Le Chaud Lapin wrote:
> On Oct 6, 2:09 pm, wrote:
>>> I believe it should be possible to explain a venturi tube, Bernoulli's
>>> principle, and a decent part of why a wing has lift, in about 2-3
>>> pages of written text, with pictures, using no formulas, not even
>>> grade-school mathematics.
>> Commonly done in many texts. You just haven't read them yet.
>
> Which texts are those?
>
> I have read some texts:
>
> 1. Jeppesen got it wrong.
> 2. Rod Machado got it wrong.
> 3. That link that with the funny color lines that was posted in this
> thread got it wrong.
> 4. If you do search in Google for "Bernoulli" + "faster" + wing +
> lift, you will see 1000's of pages that got it wrong.

I just added you to my kill file so I don't have to read your drivel any
longer so I'd say I'm the only one so far to get it right! :-)

Bertie the Bunyip[_19_]

October 6th 07, 11:12 PM

Le Chaud Lapin > wrote in
ups.com:

> On Oct 6, 2:51 pm, wrote:
>> On Oct 6, 1:32 pm, Le Chaud Lapin > wrote:
>
>> > I have read some texts:
>>
>> > 1. Jeppesen got it wrong.
>> > 2. Rod Machado got it wrong.
>> > 3. That link that with the funny color lines that was posted in
this
>> > thread got it wrong.
>> > 4. If you do search in Google for "Bernoulli" + "faster" + wing +
>> > lift, you will see 1000's of pages that got it wrong.
>>
>> All wrong, according to you. There's no point pointing out
>> any others. They'll be wrong, too.
>>
>> > Plus I watched 3 CFI's at my ground school, the one I paid money to
>> > teach me the theory of flying, get it wrong at the whiteboard.
>>
>> Rather common, distressingly. However, he may have had it
>> right; you have just determined that EVERYONE but you is wrong.
>
> It wasn't just one. It was 3. My instructor, plus 2 others. They said
> the thing that the NASA paper is calling "a myth". Who is right? The
> NASA author or the CFI's?
>
>> > And of course, if the NASA paper is true, then there are even
people
>> > in this group who got it wrong.
>>
>> > Until 3 days ago, the number of people who had gotten (partially)
>> > right was 1. The number of stories I had heard from people who got
it
>> > wrong was probably about 60-70.
>>
>> > After reading the link that Jim Logajan posted, the number of
people
>> > who are saying it's one way is 2. The number of people who are
saying
>> > it is the exact opposite is still 60-70.
>>
>> > Which textbooks would you believe if you had read 1 saying one
thing,
>> > and more than 10 others saying the exact opposite?
>>
>> Does truth in physics depend on a democratic vote?
>
> That's what I am asking...
>
> After reading 60-70 that says one thing, and seeing 2 others that says
> the exact opposite, and it just happen to be that the 2 are the ones
> that you personally agree with, which would you believe? The 60-70?
> The 2? Flip a coin?
>

You don't fly and you never wil, therefore it doesn't matter.

Bertie>

Mxsmanic

October 7th 07, 01:40 AM

writes:

> This has never been an accepted definition of angle of attack and
> your creation of it has no credibility.

Ho-hum. Acceptable to whom? Credible to whom?

Decide for yourself what you will accept or believe. Don't rely on others to
do it for you. Arguments can stand or fall on their own merit; do not rely on
hearsay and peer pressure to do your thinking for you.

> You just create even more confusion in your mind and in the minds
> of innocent truth-seekers here.

Compelling people to think for themselves will not confuse them, as long as
they are not unusually stupid. Most people don't like to think for
themselves, but they can do it if they have to.

> So you don't believe NASA or NACA or anyone else that finds
> lift at negative AOAs on some airfoils?

When I read what NASA says, it always seems to be different from what people
claim that NASA says.

Bertie the Bunyip[_19_]

October 7th 07, 01:57 AM

Mxsmanic > wrote in
:

> writes:
>
>> This has never been an accepted definition of angle of attack and
>> your creation of it has no credibility.
>
> Ho-hum. Acceptable to whom? Credible to whom?
>
> Decide for yourself what you will accept or believe. Don't rely on
> others to do it for you. Arguments can stand or fall on their own
> merit; do not rely on hearsay and peer pressure to do your thinking
> for you.
>
>> You just create even more confusion in your mind and in the minds
>> of innocent truth-seekers here.
>
> Compelling people to think for themselves will not confuse them, as
> long as they are not unusually stupid. Most people don't like to
> think for themselves, but they can do it if they have to.
>
>> So you don't believe NASA or NACA or anyone else that finds
>> lift at negative AOAs on some airfoils?
>
> When I read what NASA says, it always seems to be different from what
> people claim that NASA says.
>

Yeah, right. You have no idea what Nasa says, fjukkwit.

You don't even know how a wing works.

And you don't fly. and never will.

Bertie

[email protected]

October 7th 07, 02:05 AM

Le Chaud Lapin > wrote:
> On Oct 6, 12:45 pm, wrote:
> > Le Chaud Lapin > wrote:
> >
> > > On Oct 6, 6:38 am, Matt Whiting > wrote:
> > > > Really? Many books still can't agree on the definition of current.
> > > > Some say it is the movement of electrons and some say it is the movement
> > > > of positive charge and some say it us both. Which is the absolute
> > > > truth, Mr. Wizard?
> > > The truth is that the electrons move, not the protons.
> >
> > You've fallen into the trap you are complaining about and providing
> > a simplistic answer that isn't true under all circumstances.

> Uh...no. The difference, as I pointed out with great redunancy in my
> post, is that, in one case, there are two situations:

> 1. The truth, which the observers know.
> 2. The untruth, which the obsevers concoct to make the math simpler,
> all the while keeping in mind what the truth is.

Too simplistic.

There is more between heaven and Earth than truth and untruth.

You appear to have the same problem that MX has, i.e. a monocromatic
outlook on things which really ****es a lot of people off.

Life, physics, engineering, and flying brush a broader spectrum.

Yeah, there is a lot published about aviation by "experts" that flys
in the face of physics, but really, so what?

I have 4 bookcases of reference books on my sphere of knowledge. There
isn't one of them that doesn't have an "untruth" in them somewhere.

Does that make all those books worthless or imply no one knows the
"real" answer?

Not hardly.

If you really want to know the "truth", USNET is not the place to
find it.

<snip rest>

--
Jim Pennino

Remove .spam.sux to reply.

John Doe[_4_]

October 7th 07, 08:37 AM

wrote:

> If you really want to know the "truth", USNET is not the place to
> find it.

USENET is the wisdom and folly of the world.

Allen[_1_]

October 7th 07, 02:14 PM

"Le Chaud Lapin" > wrote in message
oups.com...
> On Oct 6, 8:53 am, Tina > wrote:
> > The hand waving about lift is equally funny: people are attaching
> > names to various theories, but the reality is the physics used in the
> > analysis of lift work well enough to predict performance. The 'wise
> > fools' will wave their hands and argue, those knowing what they are
> > doing will design airplanes.
>
> This I definitely agree with. Even if aerodynamicists (is that even a
> word) were so inept at physics that could not even calculate F=ma,
> after so many iterations, they would still be able to make highly
> refined airfoils simply because nature provides feedback to help one
> distinguish between good designs and bad designs.
>
> However, I must point out something I noted yesterday, that if you
> have theory as well as the practice, the correct theory, there might
> be opportunity to experience and entiely new realm of order and
> efficiency.
>
> I re-read the chapter on fluid mechanics in my physics book last night
> and it says exactly what that NASA article refutes. Naturally, I was
> bit perturbed - this physics book is same one used by some very good
> universities. It also read in it a near verbatim explanation of
> downwash as an example of Newton's law at work, that I found in the
> Jeppesen book, the same explanation with is rigorously refuted by
> NASA. I remember reading this chapter over and over a long time ago,
> and "not getting it", and now I realize that it's because it is most
> likely wrong.
>
> In any case, there is something to be said for re-examining the
> theory. There might be a bit of opportunity here.
>
> I *think* I understand the physics behind reduced pressure above a
> moving, appropriately shaped airfoil. *If* my suspicions are correct,
> then it should be possible to make an entirely new type of aircraft,
> where the mechanims to keep the aircraft flying are entirely different
> from what they are today. I won't say too much now. I know no one
> will consider it anyway. I'll just start fiddling, albeit slowly,
> with my copy of SolidWorks that is coming in the mail soon.
>
> I plan eventually to make a small-scale model. Hopefully, someday, I
> might find someone involved in aerodynamics/flight to help make a
> prototype.
>
> -Le Chaud Lapin-
>

Dear Le DooD,

You have got some severe imagination going on here! You need to quit
playing with lift; that has already been invented. Anti-matter and
anti-gravity is where it is at. Use your force to leap into the next era of
travel. The wheel and wing are already here.

Beam me up Scotty,

--
*H. Allen Smith*
WACO - We are all here, because we are not all there.

Bertie the Bunyip[_19_]

October 7th 07, 06:14 PM

flightoffancy > wrote in news:MPG.2172cb3db6410d90989680
@news-server.hot.rr.com:

> In article om>,
> says...
>> Now, in Chapter 3, section about airfoils, it actually says:
>>
>> "In addition to the lowered pressure, a downward-backward flow of air
>> also is generated from the top surface of the wing. The reaction to
>> this downwash results in an upward force on the wing which
demnstrates
>> Newtons' third law of motion. This action/reaction principle also is
>> apparent as the airstream strikes the lwoer surface of the wing when
>> inclinded at a small angle (the angle of attack) to its direction of
>> motion. The air is forced downward and therefore causes an upward
>> reaction resulting in positive lift."
>>
>> IMHO, the latter part of this paragraph is correct, but the former
>> part is wrong.
>
> JC, you're confusing yourself.
>
> Instead of focusing on "fixed" wing, think for a moment about
helicopter
> blades and propellers. These are airfoils not fundamentally different
> than one attached to the side of an aircraft.
>
> Anyone who has ever seen video of a helicopter hovering or has been
near
> a helicopter hovering knows that air is being pushed down by the
blades
> with massive force and that is the equal and opposite force exerted by
> the mass of air on the bottom of the blades that keeps the helicopter
> from falling out of the sky.
>
> A fixed wing aircraft is only different in that it pushes air under it
> by moving forward, rather than in a circle.
>
> The bottom line is simple: an airplane can only stay aloft by pushing
> air down.
>
> Yes, the angle of attack gives the greater impulse to knock the air
> downward. But a curved upper surface gives even more downard force to
> the air.
>
> Nit-picking Jeppensen's watered down description, which was not
authored
> for aeronautical engineers (which I note you are NOT), will not
advance
> your piloting skills in any significant way.
>
>

Nope, wrong.

Bertie

Mxsmanic

October 7th 07, 06:19 PM

flightoffancy writes:

> Yes, the angle of attack gives the greater impulse to knock the air
> downward. But a curved upper surface gives even more downard force to
> the air.

No, the curved surface simply reduces drag and/or increases the stall angle.

[email protected]

October 7th 07, 06:25 PM

John Doe > wrote:
> wrote:

> > If you really want to know the "truth", USNET is not the place to
> > find it.

> USENET is the wisdom and folly of the world.

USENET is an electronic beer and bull**** session.

The starting quality of a USENET post and a B&BS depends on the quality
and number of the attendees.

Both essentially become babbling nonsense if carried on long enough.

--
Jim Pennino

Remove .spam.sux to reply.

[email protected]

October 7th 07, 06:25 PM

flightoffancy > wrote:
> In article om>,
> says...
> > Now, in Chapter 3, section about airfoils, it actually says:
> >
> > "In addition to the lowered pressure, a downward-backward flow of air
> > also is generated from the top surface of the wing. The reaction to
> > this downwash results in an upward force on the wing which demnstrates
> > Newtons' third law of motion. This action/reaction principle also is
> > apparent as the airstream strikes the lwoer surface of the wing when
> > inclinded at a small angle (the angle of attack) to its direction of
> > motion. The air is forced downward and therefore causes an upward
> > reaction resulting in positive lift."
> >
> > IMHO, the latter part of this paragraph is correct, but the former
> > part is wrong.

> JC, you're confusing yourself.

> Instead of focusing on "fixed" wing, think for a moment about helicopter
> blades and propellers. These are airfoils not fundamentally different
> than one attached to the side of an aircraft.

> Anyone who has ever seen video of a helicopter hovering or has been near
> a helicopter hovering knows that air is being pushed down by the blades
> with massive force and that is the equal and opposite force exerted by
> the mass of air on the bottom of the blades that keeps the helicopter
> from falling out of the sky.

> A fixed wing aircraft is only different in that it pushes air under it
> by moving forward, rather than in a circle.

> The bottom line is simple: an airplane can only stay aloft by pushing
> air down.

> Yes, the angle of attack gives the greater impulse to knock the air
> downward. But a curved upper surface gives even more downard force to
> the air.

> Nit-picking Jeppensen's watered down description, which was not authored
> for aeronautical engineers (which I note you are NOT), will not advance
> your piloting skills in any significant way.

The air through the rotor disk of a gyrocopter flows upward, yet
gyrocopters fly.

--
Jim Pennino

Remove .spam.sux to reply.

Bertie the Bunyip[_19_]

October 7th 07, 06:32 PM

Mxsmanic > wrote in
:

> flightoffancy writes:
>
>> Yes, the angle of attack gives the greater impulse to knock the air
>> downward. But a curved upper surface gives even more downard force to
>> the air.
>
> No, the curved surface simply reduces drag and/or increases the stall
> angle.
>

Nope.

Bertie

Le Chaud Lapin

October 7th 07, 06:58 PM

On Oct 7, 11:54 am, flightoffancy > wrote:
> JC, you're confusing yourself.
>
> Instead of focusing on "fixed" wing, think for a moment about helicopter
> blades and propellers. These are airfoils not fundamentally different
> than one attached to the side of an aircraft.

Agree.

> Anyone who has ever seen video of a helicopter hovering or has been near
> a helicopter hovering knows that air is being pushed down by the blades
> with massive force and that is the equal and opposite force exerted by
> the mass of air on the bottom of the blades that keeps the helicopter
> from falling out of the sky.

More agreement.

> A fixed wing aircraft is only different in that it pushes air under it
> by moving forward, rather than in a circle.

Even more agreement.

> The bottom line is simple: an airplane can only stay aloft by pushing
> air down.

Still even more.

> Yes, the angle of attack gives the greater impulse to knock the air
> downward. But a curved upper surface gives even more downard force to
> the air.

Still even more. :)

> Nit-picking Jeppensen's watered down description, which was not authored
> for aeronautical engineers (which I note you are NOT), will not advance
> your piloting skills in any significant way.

There is one small problem with your exposition:

You are referring to the bottom of the wing.

Jeppesen is talking about the top of the wing.

-Le Chaud Lapin-

Le Chaud Lapin

October 7th 07, 07:15 PM

On Oct 7, 11:54 am, flightoffancy > wrote:
> In article om>,
> says...
>
> > Now, in Chapter 3, section about airfoils, it actually says:
>
> > "In addition to the lowered pressure, a downward-backward flow of air
> > also is generated from the top surface of the wing. The reaction to
> > this downwash results in an upward force on the wing which demnstrates
> > Newtons' third law of motion. This action/reaction principle also is
> > apparent as the airstream strikes the lwoer surface of the wing when
> > inclinded at a small angle (the angle of attack) to its direction of
> > motion. The air is forced downward and therefore causes an upward
> > reaction resulting in positive lift."
>
> > IMHO, the latter part of this paragraph is correct, but the former
> > part is wrong.
>
> JC, you're confusing yourself.

[Note, I just re-read your post and realized that you too are implying
that a the top wing surface can accelerate air molecules downward.,
hence my double response.]

> Instead of focusing on "fixed" wing, think for a moment about helicopter
> blades and propellers. These are airfoils not fundamentally different
> than one attached to the side of an aircraft.

Agreed.

> Anyone who has ever seen video of a helicopter hovering or has been near
> a helicopter hovering knows that air is being pushed down by the blades
> with massive force and that is the equal and opposite force exerted by
> the mass of air on the bottom of the blades that keeps the helicopter
> from falling out of the sky.

Well that is certainly true.

> A fixed wing aircraft is only different in that it pushes air under it
> by moving forward, rather than in a circle.

True.

> The bottom line is simple: an airplane can only stay aloft by pushing
> air down.

This true and not true. A wing does not necessarily have to push air
downward to cause lift.

An airplane can stay aloft if rarefication is somehow created above
the wing. This is what's happening with the blow-over-paper trick.
The air below the wing remains more or less steady at ambient
atmosphere. The air above the wing is rarefied and therefore causes
less force above the wing. The net result of the difference between
the full force below the wing and the reduced force above the wing,
minus the weight of the paper due to gravity, results in an upward net
force on the paper, causing it to rise. As soon as you stop blowing,
the ambient atmosphere works to replenish the rarefied air above the
paper to its natural state, which causes a net force on the paper due
to pressures above the paper and below the paper to equalize [taking
normal vectors into account, yada..], and gravity becomes the
determining force, causing the paper to flop back down.

Note that, in the paper trick, the airspeed of the paper is 0, and,
for all practical purpurposes, the air beneath the paper has no idea
that you're blowing on top of the wing.

> Yes, the angle of attack gives the greater impulse to knock the air
> downward. But a curved upper surface gives even more downard force to
> the air.

How? How can a the top surface of a wing cause a downward force on air
molecules that are on top of the wing?

The uppper surface of the wing can only exert a force on the air
molecules above the wing either in the upward direction, or in the
lateral direction due to friction. Ionized particles and charged
surfaces notwithstanding, it is not possible for a (theoretically
smooth) upper surface to exert a downward force on air molecules that
are sitting on top of it.

-Le Chaud Lapin-

Mxsmanic

October 7th 07, 08:23 PM

flightoffancy writes:

> It's completely absurd for someone who has not studied aeronautical
> engineering to stand up on a soap box and announce that the work of
> several generations of aeronautical engineers is WRONG -- and that he's
> leading the charge to finding out what the facts of aerodynamics really
> are.

Most incorrect theories endure for centuries, and not mere generations. That
doesn't make them any less incorrect.

[email protected]

October 7th 07, 08:23 PM

On Oct 7, 12:15 pm, Le Chaud Lapin > wrote:

> An airplane can stay aloft if rarefication is somehow created above
> the wing. This is what's happening with the blow-over-paper trick.
> The air below the wing remains more or less steady at ambient
> atmosphere. The air above the wing is rarefied and therefore causes
> less force above the wing. The net result of the difference between
> the full force below the wing and the reduced force above the wing,
> minus the weight of the paper due to gravity, results in an upward net
> force on the paper, causing it to rise. As soon as you stop blowing,
> the ambient atmosphere works to replenish the rarefied air above the
> paper to its natural state, which causes a net force on the paper due
> to pressures above the paper and below the paper to equalize [taking
> normal vectors into account, yada..], and gravity becomes the
> determining force, causing the paper to flop back down.

"Rarefaction" again. I don't see that term used by
aerodynamicists, unless they're dealing with supersonic or hypersonic
flight, and I think that's where you are haywire. (Google "aerodynamic
rarefaction" to see what comes up.) Bernoulli said that as velocity
increases, static pressure decreases. We can measure this phenomenon
inside a pipe that has no change in cross-section. As velocity
increases, the dynamic pressure increases and therefore subtracts from
the static pressure to keep the total pressure the same. On an
airfoil, the lowest pressures are found where the velocity is highest,
just atop the leading edge, where we'd expect COMPRESSION to be
happening, not rarefaction. LIFT IS GENERATED BY LOWERED STATIC
PRESSURE, NOT LOWERED DENSITY. Until you get that through your head,
you will waste years trying to prove everyone else wrong. You are, as
the NASA site says, mistakenly applying the physics of solids to the
problem, not the physics of gases.
The air moves to fill any void over a wing in subsonic
flight. It moves far more quickly that you could generate any
significant rarefaction above a wing.

From that site:

"For example, from the conservation of mass, a change in the
velocity of a gas in one direction results in a change in the velocity
of the gas in a direction perpendicular to the original change. This
is very different from the motion of solids, on which we base most of
our experiences in physics.

Dan

Le Chaud Lapin

October 7th 07, 08:24 PM

On Oct 7, 2:14 pm, flightoffancy > wrote:
> In article om>,
> says...
>
> > An airplane can stay aloft if rarefication is somehow created above
> > the wing. This is what's happening with the blow-over-paper trick.
>
> What you are saying is: if less pressure exists above the wing than
> below, then airpressure will force the wing higher, just like a round
> weight sealed in a round tube will be forced higher if the pressure
> under the weight exceeds the pressure above the weight.

Right, that's what I'm saying.

> No one questions that.
>
> But I don't think the blowing on paper "experiment" demonstrates the
> principle.

> There are too many uncontrolled variables for you to draw such a
> conclusion. For instance, it could simply be the case that some airflow
> gets under the sheet of paper and pushes it up -- just like air

Certainly you don't believe that the air is actually running around
the paper so it can get under the wing?

> impacting any plane at an angle will impart some vector force in an
> "up" direction. Also the paper does not remain stiff -- it undulates.
> That introduces a tremendous amount of complexity which casts your
> interpretation in doubt.
>
> Also: the airspeed of your paper is not 0 -- it's groundspeed is zero.

The leading edge of the airfoil, the paper in this case, will have an
airspeed of 0. You can do this by making sure that, when you blow
over the paper, your mouth is a good 3 or 4 centimeters beyond the
leading edge, on top of the paper in fact.

-Le Chaud Lapin-

Mxsmanic

October 7th 07, 08:25 PM

flightoffancy writes:

> I don't deny those facts; but the greater the curve of the wing the more
> the air pushes down behind the wing.

If that were so, then an airfoil with a half-circle for a cross-section would
produce enormous lift. In fact, this isn't the case.

> Notice the smoke flow in the photo I link to below:
>
> http://www.aa.washington.edu/uwal/uwalinfo/tech%20guide%
> 20pics/smokeflowvis.gif
>
> Granted it's at a high AoA. I'm just concluding what I have read about
> wing curvature is consistent with what I see the smoke doing in the
> picture.

But it would do the same thing with a flat airfoil.

> The explanation of why wings with greater curve bend the air down more I
> wouldn't want to say without studying aerodynamics more thoroughly.

A greater curve does not increase downwash, unless it also changes the
effective angle of attack. AOA is everything.

Le Chaud Lapin

October 7th 07, 08:29 PM

flightoffancy wrote:
> I don't deny those facts; but the greater the curve of the wing the more
> the air pushes down behind the wing.

I am assuming by "the air pushes down", you mean the air above the
wing, toward the back, not the air that is below the wing, toward the
back.

If that is the case, what is pushing the air?

-Le Chaud Lapin-

Mxsmanic

October 7th 07, 08:30 PM

Le Chaud Lapin writes:

> This true and not true. A wing does not necessarily have to push air
> downward to cause lift.

Not correct. Air (or some other mass) must be accelerated downward in order
to produce the upward acceleration of lift. There is no way around this. And
so wings must accelerate air downward in order to produce lift.

> An airplane can stay aloft if rarefication is somehow created above
> the wing. This is what's happening with the blow-over-paper trick.

An airplane can stay aloft by accelerating something downward (typically air).
No rarefaction is required.

> Note that, in the paper trick, the airspeed of the paper is 0, and,
> for all practical purpurposes, the air beneath the paper has no idea
> that you're blowing on top of the wing.

Note also that the paper isn't doing any significant lifting.

[email protected]

October 7th 07, 08:56 PM

On Oct 7, 1:29 pm, Le Chaud Lapin > wrote:
> flightoffancy wrote:
> > I don't deny those facts; but the greater the curve of the wing the more
> > the air pushes down behind the wing.
>
> I am assuming by "the air pushes down", you mean the air above the
> wing, toward the back, not the air that is below the wing, toward the
> back.
>
> If that is the case, what is pushing the air?
>
> -Le Chaud Lapin-

The wing is, of course. It's a single unit with two sides,
and if it deflects air downward the entire mass around the wing will
move downward. The raised static pressure under the wing and the
lowered static pressure atop it will both move it downward. You aren't
going to leave a void behind the wing. If you have to say that the
atmosphere above pushed it down, so be it --- but the net direction
was downward, the final position of that air was lower than before, so
displacement occurred and there was a reaction. A ship's rudder alters
the liquid flow over both sides of the rudder, and the water flows
into the low-pressure side and fills it, but the weight of water moved
times its velocity is the force applied to turn the ship.
Good picture of downwash:
http://www.physics.unlv.edu/~hilife/JetsnPlanes/downwash.jpg

Something in that picture you haven't mentioned yet at all,
maybe because your instructor hasn't dealt with it: those wingtip
vortices. Another whole are of complex aerodynamics. And a large
contributor to drag. Wing planform determines efficiency to a large
degree, but planform has to be adapted to the requirements of the
airplane.
Most instructors draw airflow over the wing from front to back,
but the increased pressure below and decreased pressure above alters
that. There are significant crossflows outward underneath, and inward
on top, with the angles at a minimum near the roots and max at the
tips, and minimum in cruise and max in slow flight.
I can hardly wait for the next argument after your next
groundschool class. It should take you a good 150 years to get a PPL
if you spend so much time nitpicking instead of studying and flying.

Dan

B A R R Y

October 7th 07, 09:30 PM

On Sun, 07 Oct 2007 17:25:03 GMT, wrote:

>
>USENET is an electronic beer and bull**** session.
>
>The starting quality of a USENET post and a B&BS depends on the quality
>and number of the attendees.
>
>Both essentially become babbling nonsense if carried on long enough.

That is the best description I've seen. <G>

[email protected]

October 7th 07, 10:15 PM

flightoffancy > wrote:
> In article >,
> says...
> >
> > The air through the rotor disk of a gyrocopter flows upward, yet
> > gyrocopters fly.
> >

> I wrote "helicopter" -- not gyrocopter.

> They are not aerodynamically the same.

I know what you wrote and I know they are not the same.

The point is that any theory that says an aircraft flys by forcing
air downward fails to explain how gyrocopters and gyroplanes fly.

Airplanes, helicopters, gyrocopters, and gyroplanes all fly in
level flight due to the lift produced by the wings and/or rotor blades.

--
Jim Pennino

Remove .spam.sux to reply.

[email protected]

October 7th 07, 10:15 PM

Mxsmanic > wrote:
> Le Chaud Lapin writes:

> > This true and not true. A wing does not necessarily have to push air
> > downward to cause lift.

> Not correct. Air (or some other mass) must be accelerated downward in order
> to produce the upward acceleration of lift. There is no way around this. And
> so wings must accelerate air downward in order to produce lift.

When in straight and level flight, the air flow through the rotor blades
of a gyrocopter is upward.

--
Jim Pennino

Remove .spam.sux to reply.

Matt Whiting

October 7th 07, 11:08 PM

wrote:
> flightoffancy > wrote:
>> In article >,
>> says...
>>> The air through the rotor disk of a gyrocopter flows upward, yet
>>> gyrocopters fly.
>>>
>
>> I wrote "helicopter" -- not gyrocopter.
>
>> They are not aerodynamically the same.
>
> I know what you wrote and I know they are not the same.
>
> The point is that any theory that says an aircraft flys by forcing
> air downward fails to explain how gyrocopters and gyroplanes fly.

How so? Just because the airflow is up through the gyro disk, doesn't
mean that the air isn't deflected downward by the passage of the rotor
disk. Did you ever notice how much AOA a gyro disk has? Think about
why this is?

Matt

Bertie the Bunyip[_19_]

October 7th 07, 11:23 PM

flightoffancy > wrote in news:MPG.2172e043702d7a5d989681
@news-server.hot.rr.com:

> In article >,
> says...
>
> "Nope, wrong" to which claims I made?
>
> I freely admit that my knowledge of aerodynamics is lacking. But I'm
> absolutely correct about Lapin's training (or utter lack thereof, in
> this case).
>
> It's completely absurd for someone who has not studied aeronautical
> engineering to stand up on a soap box and announce that the work of
> several generations of aeronautical engineers is WRONG -- and that
he's
> leading the charge to finding out what the facts of aerodynamics
really
> are.
>
> Lapin does this kind of thing on countless other news groups,
especially
> computer science groups. He denounces decades worth of work as
> inadequate or completely wrong, claims he has the right answer or
merely
> wishes to find the right answer, with the result that nearly everyone
on
> the group calls him a crank. Anyone who is really an expert in the
area
> he's challenging quickly figures out his meager explorations of the
> subject are not worth spending any time participating in.
>
> Lapin believes that he is here to TEACH us.
>
> If you can find hundreds of threads started by LCL on Google groups.
> He's an incorrigible usenet troll.
>

The downwash thing is wrong. Yes, there is some dispacemtn of air that
causes lift, but it' only a minor contribution in the bigger scheme of
things.

Bertie

Bertie the Bunyip[_19_]

October 7th 07, 11:23 PM

Mxsmanic > wrote in
:

> flightoffancy writes:
>
>> It's completely absurd for someone who has not studied aeronautical
>> engineering to stand up on a soap box and announce that the work of
>> several generations of aeronautical engineers is WRONG -- and that
>> he's leading the charge to finding out what the facts of aerodynamics
>> really are.
>
> Most incorrect theories endure for centuries, and not mere
> generations. That doesn't make them any less incorrect.
>

It does when they don't work.

Bertie

Bertie the Bunyip[_19_]

October 7th 07, 11:24 PM

Le Chaud Lapin > wrote in
ups.com:

> On Oct 7, 11:54 am, flightoffancy > wrote:
>> JC, you're confusing yourself.
>>
>> Instead of focusing on "fixed" wing, think for a moment about
helicopter
>> blades and propellers. These are airfoils not fundamentally different
>> than one attached to the side of an aircraft.
>
> Agree.
>
>> Anyone who has ever seen video of a helicopter hovering or has been
near
>> a helicopter hovering knows that air is being pushed down by the
blades
>> with massive force and that is the equal and opposite force exerted
by
>> the mass of air on the bottom of the blades that keeps the helicopter
>> from falling out of the sky.
>
> More agreement.
>
>> A fixed wing aircraft is only different in that it pushes air under
it
>> by moving forward, rather than in a circle.
>
> Even more agreement.
>
>> The bottom line is simple: an airplane can only stay aloft by pushing
>> air down.
>
> Still even more.
>
>> Yes, the angle of attack gives the greater impulse to knock the air
>> downward. But a curved upper surface gives even more downard force to
>> the air.
>
> Still even more. :)
>
>> Nit-picking Jeppensen's watered down description, which was not
authored
>> for aeronautical engineers (which I note you are NOT), will not
advance
>> your piloting skills in any significant way.
>
> There is one small problem with your exposition:
>
> You are referring to the bottom of the wing.
>
> Jeppesen is talking about the top of the wing.
>

You're an idiot.

Bertie>
>

Bertie the Bunyip[_19_]

October 7th 07, 11:29 PM

Mxsmanic > wrote in
:

> Le Chaud Lapin writes:
>
>> This true and not true. A wing does not necessarily have to push air
>> downward to cause lift.
>
> Not correct.

Yes, it is, fjukkwit

Bertie

Bertie the Bunyip[_19_]

October 7th 07, 11:30 PM

flightoffancy > wrote in
:

> In article >,
> says...
>> When in straight and level flight, the air flow through the rotor blades
>> of a gyrocopter is upward.
>>
>>
> Yeah well there's a lot of empty space between those gyrocopter blades
> for the air to blow through in an upward direction.
>
> What you don't mention is that there's also downward component to that
> airflow, when it impacts the gyrocopter blades and is knocked downward.
> The air gets knocked downard, the blades get knocked upward, the
> gyrocopter is attached to the blades, it gets held up in the air -- so
> the magic is revealed once again as "downwash".
>

Nope

Bertie

Bertie the Bunyip[_19_]

October 7th 07, 11:31 PM

Mxsmanic > wrote in
:

> flightoffancy writes:
>
>> I don't deny those facts; but the greater the curve of the wing the
>> more the air pushes down behind the wing.
>
> If that were so, then an airfoil with a half-circle for a
> cross-section would produce enormous lift. In fact, this isn't the
> case.

Actually, yes it is.

Fjukkwit

>
>> Notice the smoke flow in the photo I link to below:
>>
>> http://www.aa.washington.edu/uwal/uwalinfo/tech%20guide%
>> 20pics/smokeflowvis.gif
>>
>> Granted it's at a high AoA. I'm just concluding what I have read
>> about wing curvature is consistent with what I see the smoke doing in
>> the picture.
>
> But it would do the same thing with a flat airfoil.
>
>> The explanation of why wings with greater curve bend the air down
>> more I wouldn't want to say without studying aerodynamics more
>> thoroughly.
>
> A greater curve does not increase downwash, unless it also changes the
> effective angle of attack. AOA is everything.
>

No, it sin't everything, fjukktard

Bertie

Morgans[_2_]

October 7th 07, 11:41 PM

>> What you don't mention is that there's also downward component to that
>> airflow, when it impacts the gyrocopter blades and is knocked downward.
>> The air gets knocked downard, the blades get knocked upward, the
>> gyrocopter is attached to the blades, it gets held up in the air -- so
>> the magic is revealed once again as "downwash".
>>
>
> Nope
>
Have we got a birth of a new, less user friendly to MX, MX sockpuppet in
flightoffancy, Bertie?

The style seems rather familiar.

I'll be hard to convince otherwise.
--
Jim in NC

Bertie the Bunyip[_19_]

October 7th 07, 11:52 PM

"Morgans" > wrote in news:XgdOi.52$mo6.24
@newsfe03.lga:

>>> What you don't mention is that there's also downward component to that
>>> airflow, when it impacts the gyrocopter blades and is knocked downward.
>>> The air gets knocked downard, the blades get knocked upward, the
>>> gyrocopter is attached to the blades, it gets held up in the air -- so
>>> the magic is revealed once again as "downwash".
>>>
>>
>> Nope
>>
> Have we got a birth of a new, less user friendly to MX, MX sockpuppet in
> flightoffancy, Bertie?
>
> The style seems rather familiar.
>
> I'll be hard to convince otherwise.

Dunno, I haven't bithered looking up headers. He'd use a proxy anyway..

He'll reveal himslef by and by anyway.

Bertie

Bertie the Bunyip[_19_]

October 7th 07, 11:53 PM

Matt Whiting > wrote in
:

> wrote:
>> flightoffancy > wrote:
>>> In article >,
>>> says...
>>>> The air through the rotor disk of a gyrocopter flows upward, yet
>>>> gyrocopters fly.
>>>>
>>
>>> I wrote "helicopter" -- not gyrocopter.
>>
>>> They are not aerodynamically the same.
>>
>> I know what you wrote and I know they are not the same.
>>
>> The point is that any theory that says an aircraft flys by forcing
>> air downward fails to explain how gyrocopters and gyroplanes fly.
>
> How so? Just because the airflow is up through the gyro disk, doesn't
> mean that the air isn't deflected downward by the passage of the rotor
> disk. Did you ever notice how much AOA a gyro disk has? Think about
> why this is?

The alpha is in the blades, not the rotor.

Bertie

Bertie the Bunyip[_19_]

October 7th 07, 11:54 PM

flightoffancy > wrote in
:

> In article >,
> says...
>> flightoffancy writes:
>>
>> > Yes, the angle of attack gives the greater impulse to knock the air
>> > downward. But a curved upper surface gives even more downard force
>> > to the air.
>>
>> No, the curved surface simply reduces drag and/or increases the stall
>> angle.
>>
>
> I don't deny those facts; but the greater the curve of the wing the
> more the air pushes down behind the wing.
>

Nope

Bertie

Matt Whiting

October 8th 07, 12:20 AM

Bertie the Bunyip wrote:
> flightoffancy > wrote in news:MPG.2172e043702d7a5d989681
> @news-server.hot.rr.com:
>
>> In article >,
>> says...
>>
>> "Nope, wrong" to which claims I made?
>>
>> I freely admit that my knowledge of aerodynamics is lacking. But I'm
>> absolutely correct about Lapin's training (or utter lack thereof, in
>> this case).
>>
>> It's completely absurd for someone who has not studied aeronautical
>> engineering to stand up on a soap box and announce that the work of
>> several generations of aeronautical engineers is WRONG -- and that
> he's
>> leading the charge to finding out what the facts of aerodynamics
> really
>> are.
>>
>> Lapin does this kind of thing on countless other news groups,
> especially
>> computer science groups. He denounces decades worth of work as
>> inadequate or completely wrong, claims he has the right answer or
> merely
>> wishes to find the right answer, with the result that nearly everyone
> on
>> the group calls him a crank. Anyone who is really an expert in the
> area
>> he's challenging quickly figures out his meager explorations of the
>> subject are not worth spending any time participating in.
>>
>> Lapin believes that he is here to TEACH us.
>>
>> If you can find hundreds of threads started by LCL on Google groups.
>> He's an incorrigible usenet troll.
>>
>
>
>
> The downwash thing is wrong. Yes, there is some dispacemtn of air that
> causes lift, but it' only a minor contribution in the bigger scheme of
> things.
>
> Bertie

And what about a hovering helicopter? What is holding it up?

Matt

Jim Logajan

October 8th 07, 12:53 AM

flightoffancy > wrote:
> I thought I had read in numerous books during training that the primary
> component of lift is the air that gets knocked downward by the wing. I
> was calling that "downwash". Maybe my concept of downwash is wrong,
> maybe it's a separate consideration from the air that gets knocked
> downward by the airfoil. Hell I might not be remembering any of that
> correctly.

You appear to have the essential concept right. But aerodynamicists call it
"turning" the flow, which is different from what they call "downwash."
Here's NASA's explanations:

http://www.grc.nasa.gov/WWW/K-12/airplane/lift1.html

And if you click on "turning" you can see this explanation of the term (and
hopefully why "turning" was chosen):

http://www.grc.nasa.gov/WWW/K-12/airplane/right2.html

And this is what aerodynamicists call "downwash" :

http://www.grc.nasa.gov/WWW/K-12/airplane/downwash.html

You should understand that "Bertie" likes to play games with people's
heads. Besides, he has made mistakes with basic physics (e.g. he asserted
with absolute authority and certainty that the only time a person in a
plane would feel 1 gee of force is in straight and level flight.) So if you
are serious you probably shouldn't engage him or take anything he says
seriously. If you want some fun, then by all means have at it.

Le Chaud Lapin

October 8th 07, 01:10 AM

On Oct 7, 5:54 pm, flightoffancy > wrote:
> In article >,
> says...
>
> > The downwash thing is wrong. Yes, there is some dispacemtn of air that
> > causes lift, but it' only a minor contribution in the bigger scheme of
> > things.
>
> I admit to being a relative retard on this issue (not as retarded as a
> non-pilot probably is, but not as educated as an aeronautical engineer).
>
> I thought I had read in numerous books during training that the primary
> component of lift is the air that gets knocked downward by the wing. I
> was calling that "downwash". Maybe my concept of downwash is wrong,
> maybe it's a separate consideration from the air that gets knocked
> downward by the airfoil. Hell I might not be remembering any of that
> correctly.

Just wanted to reiterate what I said in my OP and each subsequent post
for you benefit since you just joined the discussion.

If you have an aifoil, and you move it forward, there will be
compression beneath the wing. Newton's law will be at play here, and
there will be downwash. This downwash results from the induced
pressure gradient.

That is not what I was talking about. The books that I have been
reading are talking about downwash that is _on top of_ the wing. The
pictures show air moving at an angle, backward and downward near the
trailing edge of the wing.

Note that these are two "downwashes".

I am saying that downwash on top of the wing does not generate a force
on the wing that causes the wing to move upward.

> Anyway you say downwash is minor.
>
> Well okay. But then what are the major contributions that cause lift in
> the bigger scheme of things?

-Le Chaud Lapin-

Le Chaud Lapin

October 8th 07, 01:14 AM

On Oct 7, 6:53 pm, Jim Logajan > wrote:
> flightoffancy > wrote:
> > I thought I had read in numerous books during training that the primary
> > component of lift is the air that gets knocked downward by the wing. I
> > was calling that "downwash". Maybe my concept of downwash is wrong,
> > maybe it's a separate consideration from the air that gets knocked
> > downward by the airfoil. Hell I might not be remembering any of that
> > correctly.
>
> You appear to have the essential concept right. But aerodynamicists call it
> "turning" the flow, which is different from what they call "downwash."
> Here's NASA's explanations:
>
> http://www.grc.nasa.gov/WWW/K-12/airplane/lift1.html
>
> And if you click on "turning" you can see this explanation of the term (and
> hopefully why "turning" was chosen):
>
> http://www.grc.nasa.gov/WWW/K-12/airplane/right2.html
>
> And this is what aerodynamicists call "downwash" :
>
> http://www.grc.nasa.gov/WWW/K-12/airplane/downwash.html

I wanted to thank you again for these NASA links. IThe more I read,
the more it becomes clear that is *not* universal concensus on the
basic mechanisms of flight, not even among experts.

-Le Chaud Lapin-

Jim Logajan

October 8th 07, 01:38 AM

Le Chaud Lapin > wrote:
> On Oct 7, 6:53 pm, Jim Logajan > wrote:
>> You appear to have the essential concept right. But aerodynamicists
>> call it "turning" the flow, which is different from what they call
>> "downwash." Here's NASA's explanations:
>>
>> http://www.grc.nasa.gov/WWW/K-12/airplane/lift1.html
>>
>> And if you click on "turning" you can see this explanation of the
>> term (and hopefully why "turning" was chosen):
>>
>> http://www.grc.nasa.gov/WWW/K-12/airplane/right2.html
>>
>> And this is what aerodynamicists call "downwash" :
>>
>> http://www.grc.nasa.gov/WWW/K-12/airplane/downwash.html
>
> I wanted to thank you again for these NASA links. IThe more I read,
> the more it becomes clear that is *not* universal concensus on the
> basic mechanisms of flight, not even among experts.

I'm sorry but IMHO you continue to come to the same untenable conclusion.
There is consensus among the experts. I keep giving the NASA links not
because they are in any way unique, but because it is cheaper than giving
you a list of more books on the subject that you'll never purchase and
read. They seem ideal for this particular discussion and your specific
need.

There are simplified, and therefore inaccurate, statements about
electromagnetics in books aimed at general audiences. Yet would you say
that because of these statements there is no universal consensus about
electromagnetics?

Le Chaud Lapin

October 8th 07, 02:07 AM

On Oct 7, 7:38 pm, Jim Logajan > wrote:
> I'm sorry but IMHO you continue to come to the same untenable conclusion.
> There is consensus among the experts. I keep giving the NASA links not
> because they are in any way unique, but because it is cheaper than giving
> you a list of more books on the subject that you'll never purchase and
> read. They seem ideal for this particular discussion and your specific
> need.

>From the NASA link you posted earlier:

"There are many theories of how lift is generated. Unfortunately, many
of the theories found in encyclopedias, on web sites, and even in some
textbooks are incorrect, causing unnecessary confusion for students."

That sounds to me like there are a lot of sources that are incorrect.
My Jeppesen book, for example, says the exact opposite of what NASA is
saying. Let's see...whom should I believe, the NASA version or one of
the leaders in flight education?

> There are simplified, and therefore inaccurate, statements about
> electromagnetics in books aimed at general audiences. Yet would you say
> that because of these statements there is no universal consensus about
> electromagnetics?-

Simplification does not necessarily make something in accurate. I
have studied electronics most of my life to some degree. With the
exception of maybe 5-10 incidents on esoteric, I do not recall
reading anything that is inaccurate, and in one of the cases, it was
simply a gross error made by author of book, not fundamental
difference of opinion of the underlying physics.

http://www.grc.nasa.gov/WWW/K-12/airplane/wrong1.html

NASA is not simplifying, digesting, or even offering an alternate
model that is mathematically and functionally equivalent from abstract
point of view. They are saying that the other theories are simply
wrong. That they think that the theories are wrong should be evident
from the last word in the URL above.

-Le Chaud Lapin-