Lift - Newton/Bernoulli ratio...

[Dave Doe]

Does anyone have any figures and references for about what ratio lift is
produced by Newton's Laws and Bernoulli's Laws?

I appreciate this is not a static figure - but say a yer average C-172,
or perhaps a 737.

I would hazard a semi-educated guess that lift is *primarily* produced
by angle of attack (or deflection if you like) - Newton's Laws - and by
a much lesser degree by Bernoulli's Law. I would guess that Bernoulli's
principle might create 20% of the lift a wing generates. A friend
believes it would be much lesser - about 5%.

--
Duncan.

[Orval Fairbairn]

In article >,
Dave Doe > wrote:

> Does anyone have any figures and references for about what ratio lift is
> produced by Newton's Laws and Bernoulli's Laws?
>
> I appreciate this is not a static figure - but say a yer average C-172,
> or perhaps a 737.
>
> I would hazard a semi-educated guess that lift is *primarily* produced
> by angle of attack (or deflection if you like) - Newton's Laws - and by
> a much lesser degree by Bernoulli's Law. I would guess that Bernoulli's
> principle might create 20% of the lift a wing generates. A friend
> believes it would be much lesser - about 5%.

Newton and Bernoulli approach the idea of lift generation from two
different perspectives -- both correct.

Newton's laws explain lift as an exchange of energy and momentum -- a
craft flying through the air imparts some of its momentum to the
vertical axis, which manifests itself as "lift."

Bernoulli explains the fluid mechanics of lift generation via pressure
distribution, to create "lift."

Newton explains why we get a downdraft as a plane flies overhead.

[Mxsmanic]

Dave Doe writes:

> Does anyone have any figures and references for about what ratio lift is
> produced by Newton's Laws and Bernoulli's Laws?

All lift is produced by Newton's third law of motion. Air is forced downwards
by the wings, and this produces an equal and opposite force that attempts to
raise the wings, and that is lift. How the air is forced downwards is
irrelevant, as long as it happens. In practice, principles discovered by
Bernoulli and others play a role in diverting the air flow when this is
accomplished by an airfoil.

[Brian Whatcott]

On 5/22/2011 5:15 AM, Dave Doe wrote:
> Does anyone have any figures and references for about what ratio lift is
> produced by Newton's Laws and Bernoulli's Laws?
>
> I appreciate this is not a static figure - but say a yer average C-172,
> or perhaps a 737.
>
> I would hazard a semi-educated guess that lift is *primarily* produced
> by angle of attack (or deflection if you like) - Newton's Laws - and by
> a much lesser degree by Bernoulli's Law. I would guess that Bernoulli's
> principle might create 20% of the lift a wing generates. A friend
> believes it would be much lesser - about 5%.
>

Think of it this way:
Newton: force is proportional to the mass and its acceleration.

In this context, the meaning is, to produce the aircraft's weight in
lift i.e. upwards , an airmass has to move with sufficent acceleration
to provide that up force.

Bernoulii: the mass of air flowing through a channel times its speed
gives the same product even if the channel then narrows to a waist:
the air mass has to flow faster, but its pressure drops..

In this context: air flowing in an airstream over a wing sees it bulging
(or waisting) and so that it needs to speed up, and pressure drops over
the upper wing. Arguments of this type can be used as evidence that 2/3
of the wing lift is produced at the upper surface, and 1/3 at the lower
wing surface.


The larger truth: air pressure drops over the upper surface of a wing,
and increases over the lower surface of a wing, and the resultant
downflow balances the lift on the wing.

Brian W

[Dave Doe]

In article <orfairbairn-5EFA92.14080822052011@70-3-168-
216.pools.spcsdns.net>, , Orval Fairbairn
says...
>
> In article >,
> Dave Doe > wrote:
>
> > Does anyone have any figures and references for about what ratio lift is
> > produced by Newton's Laws and Bernoulli's Laws?
> >
> > I appreciate this is not a static figure - but say a yer average C-172,
> > or perhaps a 737.
> >
> > I would hazard a semi-educated guess that lift is *primarily* produced
> > by angle of attack (or deflection if you like) - Newton's Laws - and by
> > a much lesser degree by Bernoulli's Law. I would guess that Bernoulli's
> > principle might create 20% of the lift a wing generates. A friend
> > believes it would be much lesser - about 5%.
>
> Newton and Bernoulli approach the idea of lift generation from two
> different perspectives -- both correct.
>
> Newton's laws explain lift as an exchange of energy and momentum -- a
> craft flying through the air imparts some of its momentum to the
> vertical axis, which manifests itself as "lift."
>
> Bernoulli explains the fluid mechanics of lift generation via pressure
> distribution, to create "lift."
>
> Newton explains why we get a downdraft as a plane flies overhead.

Thanks for the reply - looking for numbers, not the physics behind it.
IE looking for the percentage of lift obtained by each - and as I said,
although this is variable dependent no doubt on the plane and the
airspeed - just trying to get a rough idea (hence, say a C-172 or a
737).


--
Duncan.

[Dave Doe]

In article >,
, Mxsmanic says...
>
> Dave Doe writes:
>
> > Does anyone have any figures and references for about what ratio lift is
> > produced by Newton's Laws and Bernoulli's Laws?
>
> All lift is produced by Newton's third law of motion. Air is forced downwards
> by the wings, and this produces an equal and opposite force that attempts to
> raise the wings, and that is lift. How the air is forced downwards is
> irrelevant, as long as it happens. In practice, principles discovered by
> Bernoulli and others play a role in diverting the air flow when this is
> accomplished by an airfoil.

As said in other reply - not looking for a run-down on the physics -
looking for the *ratio* of lift obtained by each.

--
Duncan.

[Dudley Henriques[_3_]]

On May 22, 7:04*pm, Mxsmanic > wrote:
> Dave Doe writes:
> > Does anyone have any figures and references for about what ratio lift is
> > produced by Newton's Laws and Bernoulli's Laws?
>
> All lift is produced by Newton's third law of motion. Air is forced downwards
> by the wings, and this produces an equal and opposite force that attempts to
> raise the wings, and that is lift. How the air is forced downwards is
> irrelevant, as long as it happens. In practice, principles discovered by
> Bernoulli and others play a role in diverting the air flow when this is
> accomplished by an airfoil.

Actually, if I'm reading you right, I would rephrase this just a bit,
as it feeds into the problems we as instructors have in "re-
explaining" lift to students.
STRESSING either Newton or Bernoulli in the lift explanation causes
more than a modicum of confusion UNLESS it's done by including BOTH
theories in the explanation. You've done that actually. I would just
enhance things a bit more :-)
Read what Orval says above. He is absolutely correct. BOTH Newton and
Bernoulli are COMPLETE explanations for lift, which is interesting in
another respect, as neither man had lift in mind with their work.
The simple truth of it is that each explanation is totally correct and
is interchangeable with the other. Each explains the same thing
without relying on the other and BOTH are occurring simultaneously.
It's a common misconception that Bernoulli and Newton EACH contribute
INDIVIDUALLY to form a TOTAL of the lift produced. This explanation is
incorrect and should be discouraged.
When I dealt with the lift issue with instructors in seminar, my
personal approach was to favor the Newtonian explanation as in my
opinion student pilots can grasp Newton a lot easier than Bernoulli,
but I've ALWAYS made it habit NEVER to leave Bernoulli out in the
cold.
The correct way to deal with the lift issue is to explain to those
asking that BOTH explanations are complete by themselves, and Newton
might be the easier of the two to explain.
Dudley Henriques

[Private]

"Dave Doe" > wrote in message
...
> In article >,
> , Mxsmanic says...
>>
>> Dave Doe writes:
>>
>> > Does anyone have any figures and references for about what ratio lift
>> > is
>> > produced by Newton's Laws and Bernoulli's Laws?
>>
>> All lift is produced by Newton's third law of motion. Air is forced
>> downwards
>> by the wings, and this produces an equal and opposite force that attempts
>> to
>> raise the wings, and that is lift. How the air is forced downwards is
>> irrelevant, as long as it happens. In practice, principles discovered by
>> Bernoulli and others play a role in diverting the air flow when this is
>> accomplished by an airfoil.
>
> As said in other reply - not looking for a run-down on the physics -
> looking for the *ratio* of lift obtained by each.
>
> --
> Duncan.


Simple answer, there is no "ratio" -
Newton 100% + Bernoulli 100%, total = 100%

It really is a "chicken or egg" question.

Google "Newton vs. Bernoulli"
and "Newton vs. Bernoulli" NASA

I recommend
http://www.grc.nasa.gov/WWW/K-12/airplane/bernnew.html

and much more
http://www.grc.nasa.gov/WWW/K-12/airplane/short.html

When done you can also work (troll?) on other important old disputes
regarding -
high wing vs. low wing,
track up vs. north up,
and slip vs. crab with a kick.

Happy landings,

[Dave Doe]

In article <4f56d67d-f259-46e7-8e3f-
>, ,
Dudley Henriques says...
>
> On May 22, 7:04*pm, Mxsmanic > wrote:
> > Dave Doe writes:
> > > Does anyone have any figures and references for about what ratio lift is
> > > produced by Newton's Laws and Bernoulli's Laws?
> >
> > All lift is produced by Newton's third law of motion. Air is forced downwards
> > by the wings, and this produces an equal and opposite force that attempts to
> > raise the wings, and that is lift. How the air is forced downwards is
> > irrelevant, as long as it happens. In practice, principles discovered by
> > Bernoulli and others play a role in diverting the air flow when this is
> > accomplished by an airfoil.
>
> Actually, if I'm reading you right, I would rephrase this just a bit,
> as it feeds into the problems we as instructors have in "re-
> explaining" lift to students.
> STRESSING either Newton or Bernoulli in the lift explanation causes
> more than a modicum of confusion UNLESS it's done by including BOTH
> theories in the explanation. You've done that actually. I would just
> enhance things a bit more :-)
> Read what Orval says above. He is absolutely correct. BOTH Newton and
> Bernoulli are COMPLETE explanations for lift, which is interesting in
> another respect, as neither man had lift in mind with their work.
> The simple truth of it is that each explanation is totally correct and
> is interchangeable with the other. Each explains the same thing
> without relying on the other and BOTH are occurring simultaneously.
> It's a common misconception that Bernoulli and Newton EACH contribute
> INDIVIDUALLY to form a TOTAL of the lift produced. This explanation is
> incorrect and should be discouraged.

While it's true that the Bernoulli effect is part of Newtonian mechanics
- I want to know what the ratio of (gonna have to rephrase this aren't
I) is:
* an airfoil where the camber on both sides is equal and opposite
(mirroed)
vs
* an airfoil that is shaped to produce lift via Bernoulli effect.

> When I dealt with the lift issue with instructors in seminar, my
> personal approach was to favor the Newtonian explanation as in my
> opinion student pilots can grasp Newton a lot easier than Bernoulli,
> but I've ALWAYS made it habit NEVER to leave Bernoulli out in the
> cold.
> The correct way to deal with the lift issue is to explain to those
> asking that BOTH explanations are complete by themselves, and Newton
> might be the easier of the two to explain.
> Dudley Henriques

I'll rephrase it a second time. What percentage of extra lift is gained
from:
a) a plank of wood (can only produce lift via angle of attack)
vs
b) a plank of wood that is an airfoil - and is getting lift from both
angle of attack and the Bernoulli effect.

I hope that is clearer.

Here are some articles - but they produce no data to show the
addidtional lift obtained by the Bernoulli effect.

http://en.wikipedia.org/wiki/Airfoil

http://en.wikipedia.org/wiki/NACA_airfoil

http://en.wikipedia.org/wiki/Lift_(force)

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

And here is a third re-phrase...
* A yacht that has a sail made of unbendable stiff material
(will not point as high and go as fast as)...
* A yacht that has a sail of normal material and has an effective
airfoil shape and produces lift perpendicular to the sail (via the
Bernoulli effect).

Is it not a simple enough question? - I mean, really. While results
will undoubtably vary among plane types and airspeed - I'm just looking
for an approximate percentage.

Do read that: http://en.wikipedia.org/wiki/NACA_airfoil page! :)

And I don't want to get stuck on the pedantics of Newtonian physics
encompassing the Bernoulli effect - just really looking at, as said
(rephrase #4)...
- lift produced by an airfoil that has a mirrored camber top and bottom
(the zero lift line is the same as the chord line)
vs
- lift produced by a traditional airfoil

--
Duncan.

[Dave Doe]

In article >, , Private
says...
>
> "Dave Doe" > wrote in message
> ...
> > In article >,
> > , Mxsmanic says...
> >>
> >> Dave Doe writes:
> >>
> >> > Does anyone have any figures and references for about what ratio lift
> >> > is
> >> > produced by Newton's Laws and Bernoulli's Laws?
> >>
> >> All lift is produced by Newton's third law of motion. Air is forced
> >> downwards
> >> by the wings, and this produces an equal and opposite force that attempts
> >> to
> >> raise the wings, and that is lift. How the air is forced downwards is
> >> irrelevant, as long as it happens. In practice, principles discovered by
> >> Bernoulli and others play a role in diverting the air flow when this is
> >> accomplished by an airfoil.
> >
> > As said in other reply - not looking for a run-down on the physics -
> > looking for the *ratio* of lift obtained by each.
> >
> > --
> > Duncan.
>
>
> Simple answer, there is no "ratio" -
> Newton 100% + Bernoulli 100%, total = 100%

So a wing generates as much lift upside down?

What I want, is half the difference between a wing up the right way, and
the wing up the wrong way. That is, I presume, the additional lifting
force from the Bernoulli effect vs a wing with a mirrored camber
(obtaining no lift due to the Bernoulli effect).

>
> It really is a "chicken or egg" question.
>
> Google "Newton vs. Bernoulli"
> and "Newton vs. Bernoulli" NASA

Perhaps it is. I have googled.

>
> I recommend
> http://www.grc.nasa.gov/WWW/K-12/airplane/bernnew.html

Been there.

>
> and much more
> http://www.grc.nasa.gov/WWW/K-12/airplane/short.html

And there.

>
> When done you can also work (troll?) on other important old disputes
> regarding -
> high wing vs. low wing,
> track up vs. north up,
> and slip vs. crab with a kick.
>
> Happy landings,

Not interested in trolling. If you think I am, please do not reply, or
reply and say so, and I will do as such.

--
Duncan.

[Dave Doe]

In article <4f56d67d-f259-46e7-8e3f-
>, ,
Dudley Henriques says...
>
> On May 22, 7:04*pm, Mxsmanic > wrote:
> > Dave Doe writes:
> > > Does anyone have any figures and references for about what ratio lift is
> > > produced by Newton's Laws and Bernoulli's Laws?
> >
> > All lift is produced by Newton's third law of motion. Air is forced downwards
> > by the wings, and this produces an equal and opposite force that attempts to
> > raise the wings, and that is lift. How the air is forced downwards is
> > irrelevant, as long as it happens. In practice, principles discovered by
> > Bernoulli and others play a role in diverting the air flow when this is
> > accomplished by an airfoil.
>
> Actually, if I'm reading you right, I would rephrase this just a bit,
> as it feeds into the problems we as instructors have in "re-
> explaining" lift to students.
> STRESSING either Newton or Bernoulli in the lift explanation causes
> more than a modicum of confusion UNLESS it's done by including BOTH
> theories in the explanation. You've done that actually. I would just
> enhance things a bit more :-)
> Read what Orval says above. He is absolutely correct. BOTH Newton and
> Bernoulli are COMPLETE explanations for lift, which is interesting in
> another respect, as neither man had lift in mind with their work.
> The simple truth of it is that each explanation is totally correct and
> is interchangeable with the other. Each explains the same thing
> without relying on the other and BOTH are occurring simultaneously.
> It's a common misconception that Bernoulli and Newton EACH contribute
> INDIVIDUALLY to form a TOTAL of the lift produced. This explanation is
> incorrect and should be discouraged.
> When I dealt with the lift issue with instructors in seminar, my
> personal approach was to favor the Newtonian explanation as in my
> opinion student pilots can grasp Newton a lot easier than Bernoulli,
> but I've ALWAYS made it habit NEVER to leave Bernoulli out in the
> cold.
> The correct way to deal with the lift issue is to explain to those
> asking that BOTH explanations are complete by themselves, and Newton
> might be the easier of the two to explain.
> Dudley Henriques

Dudley, here are some more links I've found - only what I consider to be
the good stuff :)

http://www.physicsforums.com/showthread.php?t=19014

Nice thread that leads to this *cool* diagramatic animated page...

http://www.diam.unige.it/~irro/profilo_e.html

And I thought this was good too...

http://www.askamathematician.com/?p=1736

and this...
http://blog.sciencegeekgirl.com/2008/04/18/myth-5-how-do-airplanes-fly/

*But* - I still want to know what this is (in the last link, the last
comment)...
"Nice distinction, jim-bob. The bernouilli principle does indeed play a
role. "

How much of a role??? Gimme some numbers! Gimme some percentages!

:)

--
Duncan.

[Brian Whatcott]

On 5/23/2011 3:40 AM, Dave Doe wrote:

>> Simple answer, there is no "ratio" -
>> Newton 100% + Bernoulli 100%, total = 100%
>
> So a wing generates as much lift upside down?

For an aircraft flying level, at the same speeds, upright and inverted,
the wings produce IDENTICAL lift.
To do this, the inverted airfoil needs a higher angle of attack usually.

You are really dragging out all the old causes for disagreement: I can
see why you would be using a pseudonym

Brian W

[Dudley Henriques[_3_]]

On May 23, 3:40*am, Dave Doe > wrote:
> In article <4f56d67d-f259-46e7-8e3f-
> >, ,
> Dudley Henriques says...
>
>
>
>
>
>
>
>
>
>
>
> > On May 22, 7:04*pm, Mxsmanic > wrote:
> > > Dave Doe writes:
> > > > Does anyone have any figures and references for about what ratio lift is
> > > > produced by Newton's Laws and Bernoulli's Laws?
>
> > > All lift is produced by Newton's third law of motion. Air is forced downwards
> > > by the wings, and this produces an equal and opposite force that attempts to
> > > raise the wings, and that is lift. How the air is forced downwards is
> > > irrelevant, as long as it happens. In practice, principles discovered by
> > > Bernoulli and others play a role in diverting the air flow when this is
> > > accomplished by an airfoil.
>
> > Actually, if I'm reading you right, I would rephrase this just a bit,
> > as it feeds into the problems we as instructors have in "re-
> > explaining" lift to students.
> > STRESSING either Newton or Bernoulli in the lift explanation causes
> > more than a modicum of confusion UNLESS it's done by including BOTH
> > theories in the explanation. You've done that actually. I would just
> > enhance things a bit more :-)
> > Read what Orval says above. He is absolutely correct. BOTH Newton and
> > Bernoulli are COMPLETE explanations for lift, which is interesting in
> > another respect, as neither man had lift in mind with their work.
> > The simple truth of it is that each explanation is totally correct and
> > is interchangeable with the other. Each explains the same thing
> > without relying on the other and BOTH are occurring simultaneously.
> > It's a common misconception that Bernoulli and Newton EACH contribute
> > INDIVIDUALLY to form a TOTAL of the lift produced. This explanation is
> > incorrect and should be discouraged.
>
> While it's true that the Bernoulli effect is part of Newtonian mechanics
> - I want to know what the ratio of (gonna have to rephrase this aren't
> I) is:
> * an airfoil where the camber on both sides is equal and opposite
> (mirroed)
> vs
> * an airfoil that is shaped to produce lift via Bernoulli effect.
>
> > When I dealt with the lift issue with instructors in seminar, my
> > personal approach was to favor the Newtonian explanation as in my
> > opinion student pilots can grasp Newton a lot easier than Bernoulli,
> > but I've ALWAYS made it habit NEVER to leave Bernoulli out in the
> > cold.
> > The correct way to deal with the lift issue is to explain to those
> > asking that BOTH explanations are complete by themselves, and Newton
> > might be the easier of the two to explain.
> > Dudley Henriques
>
> I'll rephrase it a second time. *What percentage of extra lift is gained
> from:
> a) a plank of wood (can only produce lift via angle of attack)
> vs
> b) a plank of wood that is an airfoil - and is getting lift from both
> angle of attack and the Bernoulli effect.
>
> I hope that is clearer.
>
> Here are some articles - but they produce no data to show the
> addidtional lift obtained by the Bernoulli effect.
>
> http://en.wikipedia.org/wiki/Airfoil
>
> http://en.wikipedia.org/wiki/NACA_airfoil
>
> http://en.wikipedia.org/wiki/Lift_(force)
>
> http://www.grc.nasa.gov/WWW/K-12/airplane/bernnew.html
>
> And here is a third re-phrase...
> * A yacht that has a sail made of unbendable stiff material
> (will not point as high and go as fast as)...
> * A yacht that has a sail of normal material and has an effective
> airfoil shape and produces lift perpendicular to the sail (via the
> Bernoulli effect).
>
> Is it not a simple enough question? - I mean, really. *While results
> will undoubtably vary among plane types and airspeed - I'm just looking
> for an approximate percentage.
>
> Do read that:http://en.wikipedia.org/wiki/NACA_airfoilpage! :)
>
> And I don't want to get stuck on the pedantics of Newtonian physics
> encompassing the Bernoulli effect - just really looking at, as said
> (rephrase #4)...
> - lift produced by an airfoil that has a mirrored camber top and bottom
> (the zero lift line is the same as the chord line)
> vs
> - lift produced by a traditional airfoil
>
> --
> Duncan.

Simple. Newton 100% Bernoulli 100% There is no "extra lift" from
Bernoulli OR from Newton.
Both are EXACTLY equal and complete explanations for lift just
expressed differently. In other words, the total lift being produced
on either a barn door or the world's highest performance airfoil can
be explained to 100% EITHER by Newton OR by Bernoulli. It's ACTUALLY
that simple!
If you are trying to explain lift attributing any contribution to the
total lift being produced by either Bernoulli or Newton as being less
than 100% you are mistaken and using poor information.
There is simply not an instant in time when lift is being produced
where the explanation for the TOTAL lift being produced can't be shown
by EITHER a Bernoulli or a Newtonian explanation as both are equal and
total explanations of the SAME THING and are occurring SIMULTANEOUSLY!
Wikipedia serves a purpose I guess, but I prefer the Naval Test Pilot
School. I'm sure Wiki won't mind. :-))
Dudley Henriques

[Dudley Henriques[_3_]]

On May 23, 4:40*am, Dave Doe > wrote:
> In article >, , Private
> says...
>
>
>
>
>
>
>
>
>
>
>
> > "Dave Doe" > wrote in message
> ...
> > > In article >,
> > > , Mxsmanic says...
>
> > >> Dave Doe writes:

> So a wing generates as much lift upside down? *

Absolutely..........without question! The EXACT same explanation of
lift creation is in play on an inverted wing as on the upright wing.
Applies to barn doors as well.
Newton= 100% Bernoulli= 100%.
Dudley Henriques

[Mxsmanic]

Dave Doe writes:

> As said in other reply - not looking for a run-down on the physics -
> looking for the *ratio* of lift obtained by each.

I said "all lift" in answer to this. In other words, Newton's third law
generates 100% of the lift.

[Mxsmanic]

Dave Doe writes:

> So a wing generates as much lift upside down?

Yes.

> What I want, is half the difference between a wing up the right way, and
> the wing up the wrong way. That is, I presume, the additional lifting
> force from the Bernoulli effect vs a wing with a mirrored camber
> (obtaining no lift due to the Bernoulli effect).

Camber does not produce lift. Angle of attack produces lift. A flat plank will
fly as long as it has a postive angle of attack, and it can do that
upside-down or right side up.

[Mxsmanic]

Dudley Henriques writes:

> Actually, if I'm reading you right, I would rephrase this just a bit,
> as it feeds into the problems we as instructors have in "re-
> explaining" lift to students.
> STRESSING either Newton or Bernoulli in the lift explanation causes
> more than a modicum of confusion UNLESS it's done by including BOTH
> theories in the explanation. You've done that actually. I would just
> enhance things a bit more :-)

Agreed.

The problem is that all these effects interact, and explaining lift is often a
matter of preferred viewpoint, as you imply.

But it is true that lift always involves the acceleration of an air mass,
which is a matter of Newton's third law. How this acceleration is accomplished
is irrelevant, provided that it occurs. Bernoulli's effect and many other
effects help to explain why air flowing over an airfoil with a positive angle
of attack is accelerated at right angles to the direction of flow, but these
effects don't produce the lift directly, it's the acceleration that produces
the lift.

If you build something that accelerates an air mass in the same way without
any connection to Bernoulli et al., it will still fly. On the other hand, if
you build something that demonstrates Bernoulli's effect but does not
accelerate air perpendicular to its flow, no lift results.

> When I dealt with the lift issue with instructors in seminar, my
> personal approach was to favor the Newtonian explanation as in my
> opinion student pilots can grasp Newton a lot easier than Bernoulli,
> but I've ALWAYS made it habit NEVER to leave Bernoulli out in the
> cold.

Lift is produced by diverting the air flow, thanks to Newton. The diversion in
an airfoil is in part produced thanks to Bernoulli.

[Mxsmanic]

Dave Doe writes:

> While it's true that the Bernoulli effect is part of Newtonian mechanics
> - I want to know what the ratio of (gonna have to rephrase this aren't
> I) is:
> * an airfoil where the camber on both sides is equal and opposite
> (mirroed)
> vs
> * an airfoil that is shaped to produce lift via Bernoulli effect.

An airfoil doesn't need a specific shape to produce lift, as long as it's
reasonably flat. The lift is ALWAYS produced by diverting the flow of air, no
matter what the camber of the airfoil. And in airfoils, Bernoulli's effect
ALWAYS has a hand in diverting the air flow, again no matter what the camber
of the airfoil.

> I'll rephrase it a second time. What percentage of extra lift is gained
> from:
> a) a plank of wood (can only produce lift via angle of attack)
> vs
> b) a plank of wood that is an airfoil - and is getting lift from both
> angle of attack and the Bernoulli effect.

The distinction you are making doesn't exist.

A plank of wood is an airfoil when air flows over it and it has a positive
angle of attack. Newton and Bernoulli are always involved. There is no lift
without positive angle of attack. No special shape is necessary for the plank,
but it should be relatively flat and roughly edgewise to the air flow (apart
from the positive angle of attack, which is mandatory).

> Here are some articles - but they produce no data to show the
> addidtional lift obtained by the Bernoulli effect.

Because no additional lift is obtained. It's impossible to dissociate
Bernoulli from Newton for airfoils. The lift always comes from Newton, the
diversion of airflow that invokes Newton is due to Bernoulli (and other
effects, depending on how one looks at things).

> And here is a third re-phrase...
> * A yacht that has a sail made of unbendable stiff material
> (will not point as high and go as fast as)...
> * A yacht that has a sail of normal material and has an effective
> airfoil shape and produces lift perpendicular to the sail (via the
> Bernoulli effect).

A flat sail will produce lift just as well as a curved sail.

> And I don't want to get stuck on the pedantics of Newtonian physics
> encompassing the Bernoulli effect ...

Perhaps that explains why you haven't thus far understood the explanations
you've received.

[Dudley Henriques[_3_]]

On May 23, 5:20*pm, Mxsmanic > wrote:
> Dudley Henriques writes:
> > Actually, if I'm reading you right, I would rephrase this just a bit,
> > as it feeds into the problems we as instructors have in "re-
> > explaining" lift to students.
> > STRESSING either Newton or Bernoulli in the lift explanation causes
> > more than a modicum of confusion UNLESS it's done by including BOTH
> > theories in the explanation. You've done that actually. I would just
> > enhance things a bit more :-)
>
> Agreed.
>
> The problem is that all these effects interact, and explaining lift is often a
> matter of preferred viewpoint, as you imply.
>
> But it is true that lift always involves the acceleration of an air mass,
> which is a matter of Newton's third law. How this acceleration is accomplished
> is irrelevant, provided that it occurs. Bernoulli's effect and many other
> effects help to explain why air flowing over an airfoil with a positive angle
> of attack is accelerated at right angles to the direction of flow, but these
> effects don't produce the lift directly, it's the acceleration that produces
> the lift.
>
> If you build something that accelerates an air mass in the same way without
> any connection to Bernoulli et al., it will still fly. On the other hand, if
> you build something that demonstrates Bernoulli's effect but does not
> accelerate air perpendicular to its flow, no lift results.
>
> > When I dealt with the lift issue with instructors in seminar, my
> > personal approach was to favor the Newtonian explanation as in my
> > opinion student pilots can grasp Newton a lot easier than Bernoulli,
> > but I've ALWAYS made it habit NEVER to leave Bernoulli out in the
> > cold.
>
> Lift is produced by diverting the air flow, thanks to Newton. The diversion in
> an airfoil is in part produced thanks to Bernoulli.

Again correct but with a slightly different approach from me. It's
fine to quote the need for an accelerated air mass (relative wind
actually) as a necessity for lift creation. The statement is
absolutely correct, but again we have to be careful when dealing with
someone wishing to dissect Bernoulli and Newton.
The plane simple truth of it is that YES, we need relative wind to
create lift, and YES, we also need a positive angle of attack to
create lift. An airfoil no matter how efficient, at rest with no
relative wind in play, creates no lift. Same for the plank of wood.
Produce a relative wind on either and introduce a positive angle of
attack and INSTANTLY you have lift that can be explained completely
EITHER by Bernoulli or by Newton.
All we do when we stipulate that a relative wind must be present for
lift to be created is to stipulate the CONDITION under which Bernoulli
and Newton require for either to produce and explain lift.
It's a round robin that always ends up with both of these guys staring
us right in the puss with neither of them winning OVER the other .
Bernoulli 100% Newton 100% Newton the easier of the two to use as an
explanation, but NOT at the expense of Bernoulli! :-))
Dudley Henriques
Dudley Henriques

[a[_3_]]

On May 22, 10:02*pm, brian whatcott > wrote:
> On 5/22/2011 5:15 AM, Dave Doe wrote:
>
> > Does anyone have any figures and references for about what ratio lift is
> > produced by Newton's Laws and Bernoulli's Laws?
>
> > I appreciate this is not a static figure - but say a yer average C-172,
> > or perhaps a 737.
>
> > I would hazard a semi-educated guess that lift is *primarily* produced
> > by angle of attack (or deflection if you like) - Newton's Laws - and by
> > a much lesser degree by Bernoulli's Law. *I would guess that Bernoulli's
> > principle might create 20% of the lift a wing generates. *A friend
> > believes it would be much lesser - about 5%.
>
> Think of it this way:
> Newton: force is proportional to the mass and its acceleration.
>
> In this context, the meaning is, to produce the aircraft's weight in
> lift i.e. upwards , an airmass has to move *with sufficent acceleration
> to provide that up force.
>
> Bernoulii: the mass of air flowing through a channel times its speed
> gives the same product even if the channel then narrows to a waist:
> the air mass has to flow faster, but its pressure drops..
>
> In this context: air flowing in an airstream over a wing sees it bulging
> (or waisting) and so that it needs to speed up, and pressure drops over
> the upper wing. Arguments of this type can be used as evidence that 2/3
> of the wing lift is produced at the upper surface, and 1/3 at the lower
> wing surface.
>
> The larger truth: air pressure drops over the upper surface of a wing,
> and increases over the lower surface of a wing, and the resultant
> downflow balances the lift on the wing.
>
> Brian W

Does it matter to anyone posting here that the fluid flow described
by Berboulli's equation assumes the fluid is incompressible? Does
anyone here really believe there is no change in air density as if
flows at speeds of a hundred miles an hour past an airfoil? The
equation works well for water flow in pipes and around boat hulls. It
does not do such a good job of predicting pressures along an airfoil.
Stick with Newtonian Physics and the gas laws.

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[Dylan Smith[_2_]]

On 2011-05-23, Dave Doe > wrote:
> Thanks for the reply - looking for numbers, not the physics behind it.
> IE looking for the percentage of lift obtained by each - and as I said,
> although this is variable dependent no doubt on the plane and the
> airspeed - just trying to get a rough idea (hence, say a C-172 or a
> 737).

100% is produced by Newton's laws.
100% is produced by Bernoulli's principles.

The laws of physics are not additive with "x% produced by Newton and y%
by Bernouilli", they are complementary. They are merely looking at
the same phenomenon - lift - from different perspectives.

Also, note that if you hear "the air travels faster over the curved
surface of the top of the wing so it meets the air going underneath
at the same time", this is wrong. The transit times are not equal,
air going over the top of the wing gets accelerated and arrives
at the trailing edge _before_ the air that goes underneath.

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[Dylan Smith[_2_]]

On 2011-05-23, Dave Doe > wrote:
> I'll rephrase it a second time. What percentage of extra lift is gained
> from:
> a) a plank of wood (can only produce lift via angle of attack)
> vs

100% Newton
100% Bernouilli

> b) a plank of wood that is an airfoil - and is getting lift from both
> angle of attack and the Bernoulli effect.

100% Newton
100% Bernouilli

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[Dave Doe]

In article <1454525a-4a26-432c-a550-42e437fb2070
@f11g2000vbx.googlegroups.com>, , Dudley
Henriques says...
>
> On May 23, 4:40*am, Dave Doe > wrote:
> > In article >, , Private
> > says...
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > > "Dave Doe" > wrote in message
> > ...
> > > > In article >,
> > > > , Mxsmanic says...
> >
> > > >> Dave Doe writes:
>
> > So a wing generates as much lift upside down? *
>
> Absolutely..........without question! The EXACT same explanation of
> lift creation is in play on an inverted wing as on the upright wing.
> Applies to barn doors as well.
> Newton= 100% Bernoulli= 100%.
> Dudley Henriques

We're talking lift here mate - that's in the upwards direction! :)

If you are right, I'd expect to see planes with the airfoil upsidedown
(with the increased camber on the bottom), but that's not the case (and
I'm talking about the *wings* here, not the horizontal stabiliser :)

However, I'm getting what you're saying - and will now argue with my
mate that an airfoil is simply a more *efficient* device (vs. a barn
door).

He has not disagreed that:
* All wings (barn door or airfoil) create lift by deflecting
(accelerating) air (which has mass), down. Simple. F=ma.
* An airfoil produces lift by Newtonian mechanics in the same way as a
barn door (angle of attack), *but* ...
* An airfoil has increased camber over the top surface - and the air
flowing around that is pulling air down - a low pressure area is created
(and the air is accelerated over the wing (lets not go into the air
particles meet up, same as the bottom fallacy - and nor are either of us
arguing over that)).

I think you have explained though, that the Bernoulli effect occurs with
a barn door too at an angle of attack - however it is a lot less
*efficient* without that camber (which will continue to 'suck' air down
- as the camber continues to change direction - and therefore drag the
viscous air around it with it). I hope you'll agree with that.

In my reading up of the Bernoulli principle on various pages, it seems
to me that one of it's most important uses is that is often used as an
accurate *means* by which lift is calculated.

It should be an interesting argument - and many thanks for your replies.
I won't reply to your other responses - don't think it's necessary.

--
Duncan.

[Dave Doe]

In article <6def6450-011d-4f9f-8595-8c455f6b6ea0
@hd10g2000vbb.googlegroups.com>, , a says...
>
> On May 22, 10:02*pm, brian whatcott > wrote:
> > On 5/22/2011 5:15 AM, Dave Doe wrote:
> >
> > > Does anyone have any figures and references for about what ratio lift is
> > > produced by Newton's Laws and Bernoulli's Laws?
> >
> > > I appreciate this is not a static figure - but say a yer average C-172,
> > > or perhaps a 737.
> >
> > > I would hazard a semi-educated guess that lift is *primarily* produced
> > > by angle of attack (or deflection if you like) - Newton's Laws - and by
> > > a much lesser degree by Bernoulli's Law. *I would guess that Bernoulli's
> > > principle might create 20% of the lift a wing generates. *A friend
> > > believes it would be much lesser - about 5%.
> >
> > Think of it this way:
> > Newton: force is proportional to the mass and its acceleration.
> >
> > In this context, the meaning is, to produce the aircraft's weight in
> > lift i.e. upwards , an airmass has to move *with sufficent acceleration
> > to provide that up force.
> >
> > Bernoulii: the mass of air flowing through a channel times its speed
> > gives the same product even if the channel then narrows to a waist:
> > the air mass has to flow faster, but its pressure drops..
> >
> > In this context: air flowing in an airstream over a wing sees it bulging
> > (or waisting) and so that it needs to speed up, and pressure drops over
> > the upper wing. Arguments of this type can be used as evidence that 2/3
> > of the wing lift is produced at the upper surface, and 1/3 at the lower
> > wing surface.
> >
> > The larger truth: air pressure drops over the upper surface of a wing,
> > and increases over the lower surface of a wing, and the resultant
> > downflow balances the lift on the wing.
> >
> > Brian W
>
> Does it matter to anyone posting here that the fluid flow described
> by Berboulli's equation assumes the fluid is incompressible? Does
> anyone here really believe there is no change in air density as if
> flows at speeds of a hundred miles an hour past an airfoil? The
> equation works well for water flow in pipes and around boat hulls. It
> does not do such a good job of predicting pressures along an airfoil.
> Stick with Newtonian Physics and the gas laws.

I think you are right - and I think most here would agree. Hoewver it
is, for practicle purposes, considered (or treated as) incompressible at
speeds under Mach 0.3 (something I read somewhere in my research).

In reality, air is of course *very* compressible, compared to say water.

--
Duncan.

[Dave Doe]

In article >, , Dylan Smith
says...
>
> On 2011-05-23, Dave Doe > wrote:
> > Thanks for the reply - looking for numbers, not the physics behind it.
> > IE looking for the percentage of lift obtained by each - and as I said,
> > although this is variable dependent no doubt on the plane and the
> > airspeed - just trying to get a rough idea (hence, say a C-172 or a
> > 737).
>
> 100% is produced by Newton's laws.
> 100% is produced by Bernoulli's principles.
>
> The laws of physics are not additive with "x% produced by Newton and y%
> by Bernouilli", they are complementary. They are merely looking at
> the same phenomenon - lift - from different perspectives.
>
> Also, note that if you hear "the air travels faster over the curved
> surface of the top of the wing so it meets the air going underneath
> at the same time", this is wrong. The transit times are not equal,
> air going over the top of the wing gets accelerated and arrives
> at the trailing edge _before_ the air that goes underneath.

Cheers mate - no not arguing over that fallacy at all! :)

And we both agree the air over the top surface actually beats the air
underneath.

Thanks.

--
Duncan.

[Dave Doe]

In article >, , Dylan Smith
says...
>
> On 2011-05-23, Dave Doe > wrote:
> > I'll rephrase it a second time. What percentage of extra lift is gained
> > from:
> > a) a plank of wood (can only produce lift via angle of attack)
> > vs
>
> 100% Newton
> 100% Bernouilli
>
> > b) a plank of wood that is an airfoil - and is getting lift from both
> > angle of attack and the Bernoulli effect.
>
> 100% Newton
> 100% Bernouilli

Thanks - I will try and fire back a reply after our next argument over
this :)

--
Duncan.

[David Dalton]

On Wed, 25 May 2011 01:21:09 +1200, Dave Doe wrote:

> We're talking lift here mate - that's in the upwards direction! :)

Do you know of any past or present figure other than me
who uses the base chakra area muscle click (involuntary)
as closure to a magickal working? Or for divination?
I believe that Myrddin, one of the historical figures that
the legend of Merlin may have been based on, did this false
divination when he consulted his "little piggy" in the
forest. That is, I think that his "little piggy" was his
base chakra.

Oh, I forgot to define the base chakra area muscle click or short
period mulabhanda to those who don't know what a base chakra
is.

Basically the base chakra area is the perineum, or area between
the genitals and the anus. I think in a chicken this is known
as the pope's nose (correct me if that is some other area).

The click or jerk or short period mulabhanda is a clenching
of the muscles in this base chakra area. For a longer
period mulabhanda the muscles are held clenched but for
this click they are clenched and quickly released.

David

[Dudley Henriques[_3_]]

On May 23, 9:31*pm, a > wrote:
> On May 22, 10:02*pm, brian whatcott > wrote:
>
>
>
>
>
>
>
>
>
> > On 5/22/2011 5:15 AM, Dave Doe wrote:
>
> > > Does anyone have any figures and references for about what ratio lift is
> > > produced by Newton's Laws and Bernoulli's Laws?
>
> > > I appreciate this is not a static figure - but say a yer average C-172,
> > > or perhaps a 737.
>
> > > I would hazard a semi-educated guess that lift is *primarily* produced
> > > by angle of attack (or deflection if you like) - Newton's Laws - and by
> > > a much lesser degree by Bernoulli's Law. *I would guess that Bernoulli's
> > > principle might create 20% of the lift a wing generates. *A friend
> > > believes it would be much lesser - about 5%.
>
> > Think of it this way:
> > Newton: force is proportional to the mass and its acceleration.
>
> > In this context, the meaning is, to produce the aircraft's weight in
> > lift i.e. upwards , an airmass has to move *with sufficent acceleration
> > to provide that up force.
>
> > Bernoulii: the mass of air flowing through a channel times its speed
> > gives the same product even if the channel then narrows to a waist:
> > the air mass has to flow faster, but its pressure drops..
>
> > In this context: air flowing in an airstream over a wing sees it bulging
> > (or waisting) and so that it needs to speed up, and pressure drops over
> > the upper wing. Arguments of this type can be used as evidence that 2/3
> > of the wing lift is produced at the upper surface, and 1/3 at the lower
> > wing surface.
>
> > The larger truth: air pressure drops over the upper surface of a wing,
> > and increases over the lower surface of a wing, and the resultant
> > downflow balances the lift on the wing.
>
> > Brian W
> theories
> anyone here really believe there is no change in air density as if
> flows at speeds of a hundred miles an hour past an airfoil? The
> equation works well for water flow in pipes and around boat hulls. It
> does not do such a good job of predicting pressures along an airfoil.
> Stick with Newtonian Physics and the gas laws.

The ideal gas law still applies. Compressing airflow does indeed
complicate Bernoulli as do the density changes involved but Bernoulli
still holds up. Both theories remain correct even with compressible
flow. But you are correct in that the Newton explanation is FAR easier
of the two for people to deal with and understand. The only caveat I
stress to instructors when getting into the lift issue is that they
NEVER explain lift using ONLY one theory without mention of the other,
as student pilots, once exposed to the lift question will invariably
find through a credible source that BOTH Newton and Bernoulli are
correct and that each can explain exactly the same thing to the 100%
point.
Lift can be explained to death. The deeper one goes into the
explanation the more complicated it can get. Denigrating Bernoulli due
to changing density and airflow speeds causing compression factors is
NOT the way to present lift. Bernoulli stands. It's the math that gets
harder when you compress the flow that's all. All this can be avoided
by simply explaining to students that lift results when an airflow is
TURNED, and BOTH Newton and Bernoulli can be shown to cause the
airflow to turn as lift is being produced. Circulation, density,
vortices..........all part of it, but it's the turning of that airflow
that produces lift force and BOTH Bernoulli and Newton are working
equally to produce that force, only doing it differently.
Dudley Henriques

[Orval Fairbairn]

In article
>,
Dudley Henriques > wrote:

> On May 23, 9:31*pm, a > wrote:
> > On May 22, 10:02*pm, brian whatcott > wrote:
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > > On 5/22/2011 5:15 AM, Dave Doe wrote:
> >
> > > > Does anyone have any figures and references for about what ratio lift is
> > > > produced by Newton's Laws and Bernoulli's Laws?
> >
> > > > I appreciate this is not a static figure - but say a yer average C-172,
> > > > or perhaps a 737.
> >
> > > > I would hazard a semi-educated guess that lift is *primarily* produced
> > > > by angle of attack (or deflection if you like) - Newton's Laws - and by
> > > > a much lesser degree by Bernoulli's Law. *I would guess that Bernoulli's
> > > > principle might create 20% of the lift a wing generates. *A friend
> > > > believes it would be much lesser - about 5%.
> >
> > > Think of it this way:
> > > Newton: force is proportional to the mass and its acceleration.
> >
> > > In this context, the meaning is, to produce the aircraft's weight in
> > > lift i.e. upwards , an airmass has to move *with sufficent acceleration
> > > to provide that up force.
> >
> > > Bernoulii: the mass of air flowing through a channel times its speed
> > > gives the same product even if the channel then narrows to a waist:
> > > the air mass has to flow faster, but its pressure drops..
> >
> > > In this context: air flowing in an airstream over a wing sees it bulging
> > > (or waisting) and so that it needs to speed up, and pressure drops over
> > > the upper wing. Arguments of this type can be used as evidence that 2/3
> > > of the wing lift is produced at the upper surface, and 1/3 at the lower
> > > wing surface.
> >
> > > The larger truth: air pressure drops over the upper surface of a wing,
> > > and increases over the lower surface of a wing, and the resultant
> > > downflow balances the lift on the wing.
> >
> > > Brian W
> > theories
> > anyone here really believe there is no change in air density as if
> > flows at speeds of a hundred miles an hour past an airfoil? The
> > equation works well for water flow in pipes and around boat hulls. It
> > does not do such a good job of predicting pressures along an airfoil.
> > Stick with Newtonian Physics and the gas laws.
>
> The ideal gas law still applies. Compressing airflow does indeed
> complicate Bernoulli as do the density changes involved but Bernoulli
> still holds up. Both theories remain correct even with compressible
> flow. But you are correct in that the Newton explanation is FAR easier
> of the two for people to deal with and understand. The only caveat I
> stress to instructors when getting into the lift issue is that they
> NEVER explain lift using ONLY one theory without mention of the other,
> as student pilots, once exposed to the lift question will invariably
> find through a credible source that BOTH Newton and Bernoulli are
> correct and that each can explain exactly the same thing to the 100%
> point.
> Lift can be explained to death. The deeper one goes into the
> explanation the more complicated it can get. Denigrating Bernoulli due
> to changing density and airflow speeds causing compression factors is
> NOT the way to present lift. Bernoulli stands. It's the math that gets
> harder when you compress the flow that's all. All this can be avoided
> by simply explaining to students that lift results when an airflow is
> TURNED, and BOTH Newton and Bernoulli can be shown to cause the
> airflow to turn as lift is being produced. Circulation, density,
> vortices..........all part of it, but it's the turning of that airflow
> that produces lift force and BOTH Bernoulli and Newton are working
> equally to produce that force, only doing it differently.
> Dudley Henriques

AMEN!

[Dudley Henriques[_3_]]

On May 24, 3:26*pm, "Private" > wrote:
> "Dudley Henriques" > wrote in message
>
> ...
> snip
> Absolutely..........without question! *The EXACT same explanation of
> lift creation is in play on an inverted wing as on the upright wing.
> Applies to barn doors as well.
> Newton= 100% *Bernoulli= 100%.
> Dudley Henriques
>
> Greetings Dudley,
> Glad to see that you have not abandoned hope for this place.
> Hope you are well.
> Best Wishes and Happy Landings.

Thank you for the kind thought. Just passing through.
DH

[Private]

"Dudley Henriques" > wrote in message
...
snip
Absolutely..........without question! The EXACT same explanation of
lift creation is in play on an inverted wing as on the upright wing.
Applies to barn doors as well.
Newton= 100% Bernoulli= 100%.
Dudley Henriques

Greetings Dudley,
Glad to see that you have not abandoned hope for this place.
Hope you are well.
Best Wishes and Happy Landings.

[Private]

"Dave Doe" > wrote in message
...
> In article >, , Private
snip
> Not interested in trolling. If you think I am, please do not reply, or
> reply and say so,

Which is exactly what I did.

> and I will do as such.
>
> --
> Duncan.

Recent experience has made all of us here somewhat cautious regarding the
motivation of others.

[Dave Doe]

In article >, , Private
says...
>
> "Dave Doe" > wrote in message
> ...
> > In article >, , Private
> snip
> > Not interested in trolling. If you think I am, please do not reply, or
> > reply and say so,
>
> Which is exactly what I did.
>
> > and I will do as such.
> >
> > --
> > Duncan.
>
> Recent experience has made all of us here somewhat cautious regarding the
> motivation of others.

All cool by me. Thanks.

--
Duncan.

[a[_3_]]

On May 24, 10:35*am, Dudley Henriques >
wrote:
> On May 23, 9:31*pm, a > wrote:
>
>
>
>
>
>
>
>
>
> > On May 22, 10:02*pm, brian whatcott > wrote:
>
> > > On 5/22/2011 5:15 AM, Dave Doe wrote:
>
> > > > Does anyone have any figures and references for about what ratio lift is
> > > > produced by Newton's Laws and Bernoulli's Laws?
>
> > > > I appreciate this is not a static figure - but say a yer average C-172,
> > > > or perhaps a 737.
>
> > > > I would hazard a semi-educated guess that lift is *primarily* produced
> > > > by angle of attack (or deflection if you like) - Newton's Laws - and by
> > > > a much lesser degree by Bernoulli's Law. *I would guess that Bernoulli's
> > > > principle might create 20% of the lift a wing generates. *A friend
> > > > believes it would be much lesser - about 5%.
>
> > > Think of it this way:
> > > Newton: force is proportional to the mass and its acceleration.
>
> > > In this context, the meaning is, to produce the aircraft's weight in
> > > lift i.e. upwards , an airmass has to move *with sufficent acceleration
> > > to provide that up force.
>
> > > Bernoulii: the mass of air flowing through a channel times its speed
> > > gives the same product even if the channel then narrows to a waist:
> > > the air mass has to flow faster, but its pressure drops..
>
> > > In this context: air flowing in an airstream over a wing sees it bulging
> > > (or waisting) and so that it needs to speed up, and pressure drops over
> > > the upper wing. Arguments of this type can be used as evidence that 2/3
> > > of the wing lift is produced at the upper surface, and 1/3 at the lower
> > > wing surface.
>
> > > The larger truth: air pressure drops over the upper surface of a wing,
> > > and increases over the lower surface of a wing, and the resultant
> > > downflow balances the lift on the wing.
>
> > > Brian W
> > *theories
> > anyone here really believe there is no change in air density as if
> > flows at speeds of a hundred miles an hour past an airfoil? The
> > equation works well for water flow in pipes and around boat hulls. It
> > does not do such a good job of predicting pressures along an airfoil.
> > Stick with Newtonian Physics and the gas laws.
>
> The ideal gas law still applies. Compressing airflow does indeed
> complicate Bernoulli as do the density changes involved but Bernoulli
> still holds up. Both theories remain correct even with compressible
> flow. But you are correct in that the Newton explanation is FAR easier
> of the two for people to deal with and understand. The only caveat I
> stress to instructors when getting into the lift issue is that they
> NEVER explain lift using ONLY one theory without mention of the other,
> as student pilots, once exposed to the lift question will invariably
> find through a credible source that BOTH Newton and Bernoulli are
> correct and that each can explain exactly the same thing to the 100%
> point.
> Lift can be explained to death. The deeper one goes into the
> explanation the more complicated it can get. Denigrating Bernoulli due
> to changing density and airflow speeds causing compression factors is
> NOT the way to present lift. Bernoulli stands. It's the math that gets
> harder when you compress the flow that's all. All this can be avoided
> by simply explaining to students that lift results when an airflow is
> TURNED, and BOTH Newton and Bernoulli can be shown to cause the
> airflow to turn as lift is being produced. Circulation, density,
> vortices..........all part of it, but it's the turning of that airflow
> that produces lift force and BOTH Bernoulli and Newton are working
> equally to produce that force, only doing it differently.
> Dudley Henriques

Actually, a quick meander through the literature will not find
Bernoulli mentioned: in 2 D airflow studies it's gas laws and
Newtonian physics, with a heavy emphasis on experimental results.
These days, numerical methods -- what we used to call difference
equations -- seem to yield results that seem to come pretty close to
predicting experimental results. Notice especially in experiments that
chord sections have end plates so that flow really is confined to 2 D.

What is really interesting is that high performance glider wings are
long and slender: that's how they get the most efficient use of
potential energy in the form of altitude and turn it into range. I
don't know of any 4 seat complex SEL that uses the same principle and
am not sure why. My Mooney gets 20 mpg or so, sure would enjoy seeing
that change to 30!

It's nice to see a real aviation topic here, isn't it?

[Dudley Henriques[_3_]]

On May 24, 10:03*pm, a > wrote:
> On May 24, 10:35*am, Dudley Henriques >
> wrote:
>
>
>
>
>
>
>
>
>
> > On May 23, 9:31*pm, a > wrote:
>
> > > On May 22, 10:02*pm, brian whatcott > wrote:
>
> > > > On 5/22/2011 5:15 AM, Dave Doe wrote:
>
> > > > > Does anyone have any figures and references for about what ratio lift is
> > > > > produced by Newton's Laws and Bernoulli's Laws?
>
> > > > > I appreciate this is not a static figure - but say a yer average C-172,
> > > > > or perhaps a 737.
>
> > > > > I would hazard a semi-educated guess that lift is *primarily* produced
> > > > > by angle of attack (or deflection if you like) - Newton's Laws - and by
> > > > > a much lesser degree by Bernoulli's Law. *I would guess that Bernoulli's
> > > > > principle might create 20% of the lift a wing generates. *A friend
> > > > > believes it would be much lesser - about 5%.
>
> > > > Think of it this way:
> > > > Newton: force is proportional to the mass and its acceleration.
>
> > > > In this context, the meaning is, to produce the aircraft's weight in
> > > > lift i.e. upwards , an airmass has to move *with sufficent acceleration
> > > > to provide that up force.
>
> > > > Bernoulii: the mass of air flowing through a channel times its speed
> > > > gives the same product even if the channel then narrows to a waist:
> > > > the air mass has to flow faster, but its pressure drops..
>
> > > > In this context: air flowing in an airstream over a wing sees it bulging
> > > > (or waisting) and so that it needs to speed up, and pressure drops over
> > > > the upper wing. Arguments of this type can be used as evidence that 2/3
> > > > of the wing lift is produced at the upper surface, and 1/3 at the lower
> > > > wing surface.
>
> > > > The larger truth: air pressure drops over the upper surface of a wing,
> > > > and increases over the lower surface of a wing, and the resultant
> > > > downflow balances the lift on the wing.
>
> > > > Brian W
> > > *theories
> > > anyone here really believe there is no change in air density as if
> > > flows at speeds of a hundred miles an hour past an airfoil? The
> > > equation works well for water flow in pipes and around boat hulls. It
> > > does not do such a good job of predicting pressures along an airfoil.
> > > Stick with Newtonian Physics and the gas laws.
>
> > The ideal gas law still applies. Compressing airflow does indeed
> > complicate Bernoulli as do the density changes involved but Bernoulli
> > still holds up. Both theories remain correct even with compressible
> > flow. But you are correct in that the Newton explanation is FAR easier
> > of the two for people to deal with and understand. The only caveat I
> > stress to instructors when getting into the lift issue is that they
> > NEVER explain lift using ONLY one theory without mention of the other,
> > as student pilots, once exposed to the lift question will invariably
> > find through a credible source that BOTH Newton and Bernoulli are
> > correct and that each can explain exactly the same thing to the 100%
> > point.
> > Lift can be explained to death. The deeper one goes into the
> > explanation the more complicated it can get. Denigrating Bernoulli due
> > to changing density and airflow speeds causing compression factors is
> > NOT the way to present lift. Bernoulli stands. It's the math that gets
> > harder when you compress the flow that's all. All this can be avoided
> > by simply explaining to students that lift results when an airflow is
> > TURNED, and BOTH Newton and Bernoulli can be shown to cause the
> > airflow to turn as lift is being produced. Circulation, density,
> > vortices..........all part of it, but it's the turning of that airflow
> > that produces lift force and BOTH Bernoulli and Newton are working
> > equally to produce that force, only doing it differently.
> > Dudley Henriques
>
> Actually, a quick meander through the literature will not find
> Bernoulli mentioned: in 2 D airflow studies it's gas laws and
> Newtonian physics, with a heavy emphasis on experimental results.
> These days, numerical methods -- what we used to call difference
> equations -- seem to yield results that seem to come pretty close to
> predicting experimental results. Notice especially in experiments that
> chord sections have end plates so that flow really is confined to 2 D.
>
> What is really interesting is that high performance glider wings are
> long and slender: that's how they get the most efficient use of
> potential energy in the form of altitude and turn it into range. *I
> don't know of any 4 seat complex SEL that uses the same principle and
> am not sure why. *My Mooney gets 20 mpg or so, sure would enjoy seeing
> that change to 30!
>
> It's nice to see a real aviation topic here, isn't it?

I don't know what "literature" you're referring to that doesn't
mention Bernoulli when discussing lift, but I'd avoid that literature
if I were you. It's incomplete! :-))
DH

[Dave Doe]

In article <6469c134-67e0-4ca9-8dd1-
>, , a says...
>
> On May 24, 10:35*am, Dudley Henriques >
> wrote:
> > On May 23, 9:31*pm, a > wrote:
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > > On May 22, 10:02*pm, brian whatcott > wrote:
> >
> > > > On 5/22/2011 5:15 AM, Dave Doe wrote:
> >
> > > > > Does anyone have any figures and references for about what ratio lift is
> > > > > produced by Newton's Laws and Bernoulli's Laws?
> >
> > > > > I appreciate this is not a static figure - but say a yer average C-172,
> > > > > or perhaps a 737.
> >
> > > > > I would hazard a semi-educated guess that lift is *primarily* produced
> > > > > by angle of attack (or deflection if you like) - Newton's Laws - and by
> > > > > a much lesser degree by Bernoulli's Law. *I would guess that Bernoulli's
> > > > > principle might create 20% of the lift a wing generates. *A friend
> > > > > believes it would be much lesser - about 5%.
> >
> > > > Think of it this way:
> > > > Newton: force is proportional to the mass and its acceleration.
> >
> > > > In this context, the meaning is, to produce the aircraft's weight in
> > > > lift i.e. upwards , an airmass has to move *with sufficent acceleration
> > > > to provide that up force.
> >
> > > > Bernoulii: the mass of air flowing through a channel times its speed
> > > > gives the same product even if the channel then narrows to a waist:
> > > > the air mass has to flow faster, but its pressure drops..
> >
> > > > In this context: air flowing in an airstream over a wing sees it bulging
> > > > (or waisting) and so that it needs to speed up, and pressure drops over
> > > > the upper wing. Arguments of this type can be used as evidence that 2/3
> > > > of the wing lift is produced at the upper surface, and 1/3 at the lower
> > > > wing surface.
> >
> > > > The larger truth: air pressure drops over the upper surface of a wing,
> > > > and increases over the lower surface of a wing, and the resultant
> > > > downflow balances the lift on the wing.
> >
> > > > Brian W
> > > *theories
> > > anyone here really believe there is no change in air density as if
> > > flows at speeds of a hundred miles an hour past an airfoil? The
> > > equation works well for water flow in pipes and around boat hulls. It
> > > does not do such a good job of predicting pressures along an airfoil.
> > > Stick with Newtonian Physics and the gas laws.
> >
> > The ideal gas law still applies. Compressing airflow does indeed
> > complicate Bernoulli as do the density changes involved but Bernoulli
> > still holds up. Both theories remain correct even with compressible
> > flow. But you are correct in that the Newton explanation is FAR easier
> > of the two for people to deal with and understand. The only caveat I
> > stress to instructors when getting into the lift issue is that they
> > NEVER explain lift using ONLY one theory without mention of the other,
> > as student pilots, once exposed to the lift question will invariably
> > find through a credible source that BOTH Newton and Bernoulli are
> > correct and that each can explain exactly the same thing to the 100%
> > point.
> > Lift can be explained to death. The deeper one goes into the
> > explanation the more complicated it can get. Denigrating Bernoulli due
> > to changing density and airflow speeds causing compression factors is
> > NOT the way to present lift. Bernoulli stands. It's the math that gets
> > harder when you compress the flow that's all. All this can be avoided
> > by simply explaining to students that lift results when an airflow is
> > TURNED, and BOTH Newton and Bernoulli can be shown to cause the
> > airflow to turn as lift is being produced. Circulation, density,
> > vortices..........all part of it, but it's the turning of that airflow
> > that produces lift force and BOTH Bernoulli and Newton are working
> > equally to produce that force, only doing it differently.
> > Dudley Henriques
>
> Actually, a quick meander through the literature will not find
> Bernoulli mentioned: in 2 D airflow studies it's gas laws and
> Newtonian physics, with a heavy emphasis on experimental results.
> These days, numerical methods -- what we used to call difference
> equations -- seem to yield results that seem to come pretty close to
> predicting experimental results. Notice especially in experiments that
> chord sections have end plates so that flow really is confined to 2 D.
>
> What is really interesting is that high performance glider wings are
> long and slender: that's how they get the most efficient use of
> potential energy in the form of altitude and turn it into range. I
> don't know of any 4 seat complex SEL that uses the same principle and
> am not sure why. My Mooney gets 20 mpg or so, sure would enjoy seeing
> that change to 30!
>
> It's nice to see a real aviation topic here, isn't it?

Have a look at this one that I found late last night - check the section
out on Wing Efficiency - and the sections beyond it... comments welcomed
:)

http://home.comcast.net/~clipper-108/lift.pdf

--
Duncan.

[Dudley Henriques[_3_]]

On May 25, 2:36*am, Dave Doe > wrote:
> In article <6469c134-67e0-4ca9-8dd1-
> >, , a says...
>
>
>
>
>
>
>
>
>
>
>
> > On May 24, 10:35*am, Dudley Henriques >
> > wrote:
> > > On May 23, 9:31*pm, a > wrote:
>
> > > > On May 22, 10:02*pm, brian whatcott > wrote:
>
> > > > > On 5/22/2011 5:15 AM, Dave Doe wrote:
>
> > > > > > Does anyone have any figures and references for about what ratio lift is
> > > > > > produced by Newton's Laws and Bernoulli's Laws?
>
> > > > > > I appreciate this is not a static figure - but say a yer average C-172,
> > > > > > or perhaps a 737.
>
> > > > > > I would hazard a semi-educated guess that lift is *primarily* produced
> > > > > > by angle of attack (or deflection if you like) - Newton's Laws - and by
> > > > > > a much lesser degree by Bernoulli's Law. *I would guess that Bernoulli's
> > > > > > principle might create 20% of the lift a wing generates. *A friend
> > > > > > believes it would be much lesser - about 5%.
>
> > > > > Think of it this way:
> > > > > Newton: force is proportional to the mass and its acceleration.
>
> > > > > In this context, the meaning is, to produce the aircraft's weight in
> > > > > lift i.e. upwards , an airmass has to move *with sufficent acceleration
> > > > > to provide that up force.
>
> > > > > Bernoulii: the mass of air flowing through a channel times its speed
> > > > > gives the same product even if the channel then narrows to a waist:
> > > > > the air mass has to flow faster, but its pressure drops..
>
> > > > > In this context: air flowing in an airstream over a wing sees it bulging
> > > > > (or waisting) and so that it needs to speed up, and pressure drops over
> > > > > the upper wing. Arguments of this type can be used as evidence that 2/3
> > > > > of the wing lift is produced at the upper surface, and 1/3 at the lower
> > > > > wing surface.
>
> > > > > The larger truth: air pressure drops over the upper surface of a wing,
> > > > > and increases over the lower surface of a wing, and the resultant
> > > > > downflow balances the lift on the wing.
>
> > > > > Brian W
> > > > *theories
> > > > anyone here really believe there is no change in air density as if
> > > > flows at speeds of a hundred miles an hour past an airfoil? The
> > > > equation works well for water flow in pipes and around boat hulls. It
> > > > does not do such a good job of predicting pressures along an airfoil.
> > > > Stick with Newtonian Physics and the gas laws.
>
> > > The ideal gas law still applies. Compressing airflow does indeed
> > > complicate Bernoulli as do the density changes involved but Bernoulli
> > > still holds up. Both theories remain correct even with compressible
> > > flow. But you are correct in that the Newton explanation is FAR easier
> > > of the two for people to deal with and understand. The only caveat I
> > > stress to instructors when getting into the lift issue is that they
> > > NEVER explain lift using ONLY one theory without mention of the other,
> > > as student pilots, once exposed to the lift question will invariably
> > > find through a credible source that BOTH Newton and Bernoulli are
> > > correct and that each can explain exactly the same thing to the 100%
> > > point.
> > > Lift can be explained to death. The deeper one goes into the
> > > explanation the more complicated it can get. Denigrating Bernoulli due
> > > to changing density and airflow speeds causing compression factors is
> > > NOT the way to present lift. Bernoulli stands. It's the math that gets
> > > harder when you compress the flow that's all. All this can be avoided
> > > by simply explaining to students that lift results when an airflow is
> > > TURNED, and BOTH Newton and Bernoulli can be shown to cause the
> > > airflow to turn as lift is being produced. Circulation, density,
> > > vortices..........all part of it, but it's the turning of that airflow
> > > that produces lift force and BOTH Bernoulli and Newton are working
> > > equally to produce that force, only doing it differently.
> > > Dudley Henriques
>
> > Actually, a quick meander through the literature will not find
> > Bernoulli mentioned: in 2 D airflow studies it's gas laws and
> > Newtonian physics, with a heavy emphasis on experimental results.
> > These days, numerical methods -- what we used to call difference
> > equations -- seem to yield results that seem to come pretty close to
> > predicting experimental results. Notice especially in experiments that
> > chord sections have end plates so that flow really is confined to 2 D.
>
> > What is really interesting is that high performance glider wings are
> > long and slender: that's how they get the most efficient use of
> > potential energy in the form of altitude and turn it into range. *I
> > don't know of any 4 seat complex SEL that uses the same principle and
> > am not sure why. *My Mooney gets 20 mpg or so, sure would enjoy seeing
> > that change to 30!
>
> > It's nice to see a real aviation topic here, isn't it?
>
> Have a look at this one that I found late last night - check the section
> out on Wing Efficiency - and the sections beyond it... comments welcomed
> :)
>
> http://home.comcast.net/~clipper-108/lift.pdf
>
> --
> Duncan.

I didn't have to get past the first several paragraphs to see what was
going on here with this paper. It becomes apparent with the sentence,
"Bernoulli relies on equal transit times". This statement is false on
premise so all that comes after it has to be flawed.
Bernoulli absolutely and most certainly does NOT rely on equal
transit. Equal transit is incorrect in ALL explanations on lift
development and in fact is probably responsible for more
misunderstanding about Bernoulli that anything else.
This paper represents just more of the misunderstanding surrounding
lift. It looks good on the face, is well written, but misses the basic
point that you don't need equal transit to prove Bernoulli.
The main point this paper makes is that if you believe you need equal
transit to prove Bernoulli you need to dig into lift development a bit
deeper, especially the Bernoulli end of things.
Point of note;
Be wary of any and all papers on this subject written by individuals.
Be wary of me as well. Do some SERIOUS homework on this if you are
really interested.

One of the most credible, if not THE most credible text ever written
on these subjects is the bible I have used myself all through my
career, and recommended to every instructor and pilot who has ever
crossed my path. The book is well worth the money and every serious
pilot should own a copy. It's a bit heavy on math but crystal clear on
explanation.
Get a copy of "Aerodynamics For Naval Aviators" by Hurt. Read the
section on lift and you will never again have any doubt at all about
either Newton or Bernoulli being a 100% explanation for how lift is
createdi.
Dudley Henriques

[Dylan Smith[_2_]]

On 2011-05-25, a > wrote:
> What is really interesting is that high performance glider wings are
> long and slender: that's how they get the most efficient use of
> potential energy in the form of altitude and turn it into range. I
> don't know of any 4 seat complex SEL that uses the same principle and
> am not sure why. My Mooney gets 20 mpg or so, sure would enjoy seeing
> that change to 30!

The reason why is that you have tradeoffs - long and slender wings
won't work so well for a much heavier plane (more heavy structure) that has
to go much faster (more form drag). Even performance gliders are slow
compared to, say, a Beech Bonanza (I got all excited about flying
a Discus, now I could transit across areas of sink at a whopping 90
knots or so).

Some 4 seat planes have longer, higher aspect ratio wings than was
traditional, for instance the Diamond DA-40 which has trouble fitting
in a lot of T-hangars due to its wingspan of 40-odd feet. However I suspect
much beyond that wingspan you're going to start losing more than you
gain in parasitic drag and extra structural weight to have a very
long, slender wing in a 4 seat plane that goes more than 140 knots in
cruise.

[george]

On May 26, 1:06*am, Dudley Henriques >
wrote:
> On May 25, 2:36*am, Dave Doe > wrote:
>
>
>
> > In article <6469c134-67e0-4ca9-8dd1-
> > >, , a says....
>
> > > On May 24, 10:35*am, Dudley Henriques >
> > > wrote:
> > > > On May 23, 9:31*pm, a > wrote:
>
> > > > > On May 22, 10:02*pm, brian whatcott > wrote:
>
> > > > > > On 5/22/2011 5:15 AM, Dave Doe wrote:
>
> > > > > > > Does anyone have any figures and references for about what ratio lift is
> > > > > > > produced by Newton's Laws and Bernoulli's Laws?
>
> > > > > > > I appreciate this is not a static figure - but say a yer average C-172,
> > > > > > > or perhaps a 737.
>
> > > > > > > I would hazard a semi-educated guess that lift is *primarily* produced
> > > > > > > by angle of attack (or deflection if you like) - Newton's Laws - and by
> > > > > > > a much lesser degree by Bernoulli's Law. *I would guess that Bernoulli's
> > > > > > > principle might create 20% of the lift a wing generates. *A friend
> > > > > > > believes it would be much lesser - about 5%.
>
> > > > > > Think of it this way:
> > > > > > Newton: force is proportional to the mass and its acceleration.
>
> > > > > > In this context, the meaning is, to produce the aircraft's weight in
> > > > > > lift i.e. upwards , an airmass has to move *with sufficent acceleration
> > > > > > to provide that up force.
>
> > > > > > Bernoulii: the mass of air flowing through a channel times its speed
> > > > > > gives the same product even if the channel then narrows to a waist:
> > > > > > the air mass has to flow faster, but its pressure drops..
>
> > > > > > In this context: air flowing in an airstream over a wing sees it bulging
> > > > > > (or waisting) and so that it needs to speed up, and pressure drops over
> > > > > > the upper wing. Arguments of this type can be used as evidence that 2/3
> > > > > > of the wing lift is produced at the upper surface, and 1/3 at the lower
> > > > > > wing surface.
>
> > > > > > The larger truth: air pressure drops over the upper surface of a wing,
> > > > > > and increases over the lower surface of a wing, and the resultant
> > > > > > downflow balances the lift on the wing.
>
> > > > > > Brian W
> > > > > *theories
> > > > > anyone here really believe there is no change in air density as if
> > > > > flows at speeds of a hundred miles an hour past an airfoil? The
> > > > > equation works well for water flow in pipes and around boat hulls.. It
> > > > > does not do such a good job of predicting pressures along an airfoil.
> > > > > Stick with Newtonian Physics and the gas laws.
>
> > > > The ideal gas law still applies. Compressing airflow does indeed
> > > > complicate Bernoulli as do the density changes involved but Bernoulli
> > > > still holds up. Both theories remain correct even with compressible
> > > > flow. But you are correct in that the Newton explanation is FAR easier
> > > > of the two for people to deal with and understand. The only caveat I
> > > > stress to instructors when getting into the lift issue is that they
> > > > NEVER explain lift using ONLY one theory without mention of the other,
> > > > as student pilots, once exposed to the lift question will invariably
> > > > find through a credible source that BOTH Newton and Bernoulli are
> > > > correct and that each can explain exactly the same thing to the 100%
> > > > point.
> > > > Lift can be explained to death. The deeper one goes into the
> > > > explanation the more complicated it can get. Denigrating Bernoulli due
> > > > to changing density and airflow speeds causing compression factors is
> > > > NOT the way to present lift. Bernoulli stands. It's the math that gets
> > > > harder when you compress the flow that's all. All this can be avoided
> > > > by simply explaining to students that lift results when an airflow is
> > > > TURNED, and BOTH Newton and Bernoulli can be shown to cause the
> > > > airflow to turn as lift is being produced. Circulation, density,
> > > > vortices..........all part of it, but it's the turning of that airflow
> > > > that produces lift force and BOTH Bernoulli and Newton are working
> > > > equally to produce that force, only doing it differently.
> > > > Dudley Henriques
>
> > > Actually, a quick meander through the literature will not find
> > > Bernoulli mentioned: in 2 D airflow studies it's gas laws and
> > > Newtonian physics, with a heavy emphasis on experimental results.
> > > These days, numerical methods -- what we used to call difference
> > > equations -- seem to yield results that seem to come pretty close to
> > > predicting experimental results. Notice especially in experiments that
> > > chord sections have end plates so that flow really is confined to 2 D..
>
> > > What is really interesting is that high performance glider wings are
> > > long and slender: that's how they get the most efficient use of
> > > potential energy in the form of altitude and turn it into range. *I
> > > don't know of any 4 seat complex SEL that uses the same principle and
> > > am not sure why. *My Mooney gets 20 mpg or so, sure would enjoy seeing
> > > that change to 30!
>
> > > It's nice to see a real aviation topic here, isn't it?
>
> > Have a look at this one that I found late last night - check the section
> > out on Wing Efficiency - and the sections beyond it... comments welcomed
> > :)
>
> >http://home.comcast.net/~clipper-108/lift.pdf
>
> > --
> > Duncan.
>
> I didn't have to get past the first several paragraphs to see what was
> going on here with this paper. It becomes apparent with the sentence,
> "Bernoulli relies on equal transit times". This statement is false on
> premise so all that comes after it has to be flawed.
> Bernoulli absolutely and most certainly does NOT rely on equal
> transit. Equal transit is incorrect in ALL explanations on lift
> development and in fact is probably responsible for more
> misunderstanding about Bernoulli that anything else.
> This paper represents just more of the misunderstanding surrounding
> lift. It looks good on the face, is well written, but misses the basic
> point that you don't need equal transit to prove Bernoulli.
> The main point this paper makes is that if you believe you need equal
> transit to prove Bernoulli you need to dig into lift development a bit
> deeper, especially the Bernoulli end of things.
> Point of note;
> Be wary of any and all papers on this subject written by individuals.
> Be wary of me as well. Do some SERIOUS homework on this if you are
> really interested.
>
> One of the most credible, if not THE most credible text ever written
> on these subjects is the bible I have used myself all through my
> career, and recommended to every instructor *and pilot who has ever
> crossed my path. The book is well worth the money and every serious
> pilot should own a copy. It's a bit heavy on math but crystal clear on
> explanation.
> Get a copy of "Aerodynamics For Naval Aviators" by Hurt. Read the
> section on lift and you will never again have any doubt at all about
> either Newton or Bernoulli being a 100% explanation for how lift is
> createdi.
> Dudley Henriques
Yup
Or "Flight without Formulae" for simple easy to understand reading to
prepare one for the more complex explanations out there...

[Dave Doe]

In article <47971036-2b4d-4297-bcbf-
>, ,
Dudley Henriques says...
>
> On May 25, 2:36*am, Dave Doe > wrote:
> > In article <6469c134-67e0-4ca9-8dd1-
> > >, , a says...
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > > On May 24, 10:35*am, Dudley Henriques >
> > > wrote:
> > > > On May 23, 9:31*pm, a > wrote:
> >
> > > > > On May 22, 10:02*pm, brian whatcott > wrote:
> >
> > > > > > On 5/22/2011 5:15 AM, Dave Doe wrote:
> >
> > > > > > > Does anyone have any figures and references for about what ratio lift is
> > > > > > > produced by Newton's Laws and Bernoulli's Laws?
> >
> > > > > > > I appreciate this is not a static figure - but say a yer average C-172,
> > > > > > > or perhaps a 737.
> >
> > > > > > > I would hazard a semi-educated guess that lift is *primarily* produced
> > > > > > > by angle of attack (or deflection if you like) - Newton's Laws - and by
> > > > > > > a much lesser degree by Bernoulli's Law. *I would guess that Bernoulli's
> > > > > > > principle might create 20% of the lift a wing generates. *A friend
> > > > > > > believes it would be much lesser - about 5%.
> >
> > > > > > Think of it this way:
> > > > > > Newton: force is proportional to the mass and its acceleration.
> >
> > > > > > In this context, the meaning is, to produce the aircraft's weight in
> > > > > > lift i.e. upwards , an airmass has to move *with sufficent acceleration
> > > > > > to provide that up force.
> >
> > > > > > Bernoulii: the mass of air flowing through a channel times its speed
> > > > > > gives the same product even if the channel then narrows to a waist:
> > > > > > the air mass has to flow faster, but its pressure drops..
> >
> > > > > > In this context: air flowing in an airstream over a wing sees it bulging
> > > > > > (or waisting) and so that it needs to speed up, and pressure drops over
> > > > > > the upper wing. Arguments of this type can be used as evidence that 2/3
> > > > > > of the wing lift is produced at the upper surface, and 1/3 at the lower
> > > > > > wing surface.
> >
> > > > > > The larger truth: air pressure drops over the upper surface of a wing,
> > > > > > and increases over the lower surface of a wing, and the resultant
> > > > > > downflow balances the lift on the wing.
> >
> > > > > > Brian W
> > > > > *theories
> > > > > anyone here really believe there is no change in air density as if
> > > > > flows at speeds of a hundred miles an hour past an airfoil? The
> > > > > equation works well for water flow in pipes and around boat hulls. It
> > > > > does not do such a good job of predicting pressures along an airfoil.
> > > > > Stick with Newtonian Physics and the gas laws.
> >
> > > > The ideal gas law still applies. Compressing airflow does indeed
> > > > complicate Bernoulli as do the density changes involved but Bernoulli
> > > > still holds up. Both theories remain correct even with compressible
> > > > flow. But you are correct in that the Newton explanation is FAR easier
> > > > of the two for people to deal with and understand. The only caveat I
> > > > stress to instructors when getting into the lift issue is that they
> > > > NEVER explain lift using ONLY one theory without mention of the other,
> > > > as student pilots, once exposed to the lift question will invariably
> > > > find through a credible source that BOTH Newton and Bernoulli are
> > > > correct and that each can explain exactly the same thing to the 100%
> > > > point.
> > > > Lift can be explained to death. The deeper one goes into the
> > > > explanation the more complicated it can get. Denigrating Bernoulli due
> > > > to changing density and airflow speeds causing compression factors is
> > > > NOT the way to present lift. Bernoulli stands. It's the math that gets
> > > > harder when you compress the flow that's all. All this can be avoided
> > > > by simply explaining to students that lift results when an airflow is
> > > > TURNED, and BOTH Newton and Bernoulli can be shown to cause the
> > > > airflow to turn as lift is being produced. Circulation, density,
> > > > vortices..........all part of it, but it's the turning of that airflow
> > > > that produces lift force and BOTH Bernoulli and Newton are working
> > > > equally to produce that force, only doing it differently.
> > > > Dudley Henriques
> >
> > > Actually, a quick meander through the literature will not find
> > > Bernoulli mentioned: in 2 D airflow studies it's gas laws and
> > > Newtonian physics, with a heavy emphasis on experimental results.
> > > These days, numerical methods -- what we used to call difference
> > > equations -- seem to yield results that seem to come pretty close to
> > > predicting experimental results. Notice especially in experiments that
> > > chord sections have end plates so that flow really is confined to 2 D.
> >
> > > What is really interesting is that high performance glider wings are
> > > long and slender: that's how they get the most efficient use of
> > > potential energy in the form of altitude and turn it into range. *I
> > > don't know of any 4 seat complex SEL that uses the same principle and
> > > am not sure why. *My Mooney gets 20 mpg or so, sure would enjoy seeing
> > > that change to 30!
> >
> > > It's nice to see a real aviation topic here, isn't it?
> >
> > Have a look at this one that I found late last night - check the section
> > out on Wing Efficiency - and the sections beyond it... comments welcomed
> > :)
> >
> > http://home.comcast.net/~clipper-108/lift.pdf
> >
> > --
> > Duncan.
>
> I didn't have to get past the first several paragraphs to see what was
> going on here with this paper. It becomes apparent with the sentence,
> "Bernoulli relies on equal transit times". This statement is false on
> premise so all that comes after it has to be flawed.
> Bernoulli absolutely and most certainly does NOT rely on equal
> transit. Equal transit is incorrect in ALL explanations on lift

I don't think you read or understood the paper very well. The author is
saying that that is the common misconception - he terms it, "Popular
Description" - which he points out is incorrect - as you do.

--
Duncan.

[Dudley Henriques[_3_]]

On May 25, 6:55*pm, Dave Doe > wrote:
> In article <47971036-2b4d-4297-bcbf-
> >, ,
> Dudley Henriques says...
>
>
>
>
>
>
>
>
>
>
>
> > On May 25, 2:36 am, Dave Doe > wrote:
> > > In article <6469c134-67e0-4ca9-8dd1-
> > > >, , a says....
>
> > > > On May 24, 10:35 am, Dudley Henriques >
> > > > wrote:
> > > > > On May 23, 9:31 pm, a > wrote:
>
> > > > > > On May 22, 10:02 pm, brian whatcott > wrote:
>
> > > > > > > On 5/22/2011 5:15 AM, Dave Doe wrote:
>
> > > > > > > > Does anyone have any figures and references for about what ratio lift is
> > > > > > > > produced by Newton's Laws and Bernoulli's Laws?
>
> > > > > > > > I appreciate this is not a static figure - but say a yer average C-172,
> > > > > > > > or perhaps a 737.
>
> > > > > > > > I would hazard a semi-educated guess that lift is *primarily* produced
> > > > > > > > by angle of attack (or deflection if you like) - Newton's Laws - and by
> > > > > > > > a much lesser degree by Bernoulli's Law. I would guess that Bernoulli's
> > > > > > > > principle might create 20% of the lift a wing generates. A friend
> > > > > > > > believes it would be much lesser - about 5%.
>
> > > > > > > Think of it this way:
> > > > > > > Newton: force is proportional to the mass and its acceleration.

[Dudley Henriques[_3_]]

On May 25, 6:55*pm, Dave Doe > wrote:
> In article <47971036-2b4d-4297-bcbf-
> >, ,
> Dudley Henriques says...
>
>
>
>
>
>
>
>
>
>
>
> > On May 25, 2:36 am, Dave Doe > wrote:
> > > In article <6469c134-67e0-4ca9-8dd1-
> > > >, , a says....
>
> > > > On May 24, 10:35 am, Dudley Henriques >
> > > > wrote:
> > > > > On May 23, 9:31 pm, a > wrote:
>
> > > > > > On May 22, 10:02 pm, brian whatcott > wrote:
>
> > > > > > > On 5/22/2011 5:15 AM, Dave Doe wrote:
>
> > > > > > > > Does anyone have any figures and references for about what ratio lift is
> > > > > > > > produced by Newton's Laws and Bernoulli's Laws?
>
> > > > > > > > I appreciate this is not a static figure - but say a yer average C-172,
> > > > > > > > or perhaps a 737.
>
> > > > > > > > I would hazard a semi-educated guess that lift is *primarily* produced
> > > > > > > > by angle of attack (or deflection if you like) - Newton's Laws - and by
> > > > > > > > a much lesser degree by Bernoulli's Law. I would guess that Bernoulli's
> > > > > > > > principle might create 20% of the lift a wing generates. A friend
> > > > > > > > believes it would be much lesser - about 5%.
>
> > > > > > > Think of it this way:
> > > > > > > Newton: force is proportional to the mass and its acceleration.

[Mxsmanic]

Dave Doe writes:

> If you are right, I'd expect to see planes with the airfoil upsidedown
> (with the increased camber on the bottom), but that's not the case (and
> I'm talking about the *wings* here, not the horizontal stabiliser :)

Actually it is. NASA has tested airfoils with a camber on the bottom, and they
fly just as well as airfoils with a camber on the top. I don't know what
became of the research, though. As a I recall, they had some airfoils that
were very good at preventing stalls, but I suppose they had other
disadvantages (drag problems?).

> I think you have explained though, that the Bernoulli effect occurs with
> a barn door too at an angle of attack - however it is a lot less
> *efficient* without that camber (which will continue to 'suck' air down
> - as the camber continues to change direction - and therefore drag the
> viscous air around it with it). I hope you'll agree with that.

Good airfoil designs can reduce drag and improve stall characteristics, but
generating lift requires only a positive angle of attack.

[Brian Whatcott]

On 5/23/2011 4:20 PM, Mxsmanic wrote:

>> When I dealt with the lift issue with instructors in seminar, my
>> personal approach was to favor the Newtonian explanation as in my
>> opinion student pilots can grasp Newton a lot easier than Bernoulli,
>> but I've ALWAYS made it habit NEVER to leave Bernoulli out in the
>> cold.

Dealt with lift - with instructors - in seminar?

Do tell! :-)

Brian W

[Brian Whatcott]

On 5/25/2011 1:36 AM, Dave Doe wrote:

> Have a look at this one that I found late last night - check the section
> out on Wing Efficiency - and the sections beyond it... comments welcomed
> :)
>
> http://home.comcast.net/~clipper-108/lift.pdf
>

I looked: it prefaced the story by saying that if the Newtonian
explanation (f=m.a) is used, people understand more easily than if the
Bernouillian explanation is offered.

Who would disagree with that?

Brian W

[Dudley Henriques[_3_]]

On May 28, 2:27*pm, brian whatcott > wrote:
> On 5/23/2011 4:20 PM, Mxsmanic wrote:
>
> >> When I dealt with the lift issue with instructors in seminar, my
> >> personal approach was to favor the Newtonian explanation as in my
> >> opinion student pilots can grasp Newton a lot easier than Bernoulli,
> >> but I've ALWAYS made it habit NEVER to leave Bernoulli out in the
> >> cold.
>
> Dealt with lift - with instructors * - in seminar?
>
> Do tell! * *:-)
>
> Brian W

Not sure I understand where you're going with this. I used to give
seminars with instructors in attendance. Simple!
DH

[Brian Whatcott]

On 5/28/2011 2:01 PM, Dudley Henriques wrote:
> On May 28, 2:27 pm, brian > wrote:
>> On 5/23/2011 4:20 PM, Mxsmanic wrote:
>>
>>>> When I dealt with the lift issue with instructors in seminar, my
>>>> personal approach was to favor the Newtonian explanation as in my
>>>> opinion student pilots can grasp Newton a lot easier than Bernoulli,
>>>> but I've ALWAYS made it habit NEVER to leave Bernoulli out in the
>>>> cold.
>>
>> Dealt with lift - with instructors - in seminar?
>>
>> Do tell! :-)
>>
>> Brian W
>
> Not sure I understand where you're going with this. I used to give
> seminars with instructors in attendance. Simple!
> DH


Oops! Missed the attribution bars. NOW it makes sense.

Brian W

[george]

On May 29, 8:11*am, brian whatcott > wrote:
> On 5/28/2011 2:01 PM, Dudley Henriques wrote:
>
>
>
>
>
>
>
>
>
> > On May 28, 2:27 pm, brian > *wrote:
> >> On 5/23/2011 4:20 PM, Mxsmanic wrote:
>
> >>>> When I dealt with the lift issue with instructors in seminar, my
> >>>> personal approach was to favor the Newtonian explanation as in my
> >>>> opinion student pilots can grasp Newton a lot easier than Bernoulli,
> >>>> but I've ALWAYS made it habit NEVER to leave Bernoulli out in the
> >>>> cold.
>
> >> Dealt with lift - with instructors * - in seminar?
>
> >> Do tell! * *:-)
>
> >> Brian W
>
> > Not sure I understand where you're going with this. I used to give
> > seminars with instructors in attendance. Simple!
> > DH
>
> Oops! Missed the attribution bars. NOW it makes sense.

You thought mixedup was lecturing instructors ?
ROTFL
Must be an addon to MFS