Backwash Causes Lift?

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.

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.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-

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

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

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

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

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

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

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. [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.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

"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