Randy Poe wrote in
oups.com:

On Oct 9, 4:08 pm, Le Chaud Lapin wrote:
Hi All,

There is a long discussion ongoing in rec.aviation.piloting about
what
causes lift on a plane.

Heh. I know the argument. I think it's broken out here (sci.physics)
many times.

(a) It's the Bernoulli effect due to the shape of the
wing cross-section, the way we were all taught as kids.

(b) No, it's just the angle of attack.

I'm no expert, but I heard enough in similar arguments here
to convince me that the angle-of-attack people are right and
the shape of the wing has more to do with controlling
turbulence.

There are people in the pilot's group, who think that lift on a wing
is analyzed as such:

1. There is air on outside of top of wing that is pushing down, but
reduced because of aerodynamics.
2. The *inside* of the wing contains air pushing up against the
underside of top of wing .

Er... that's a new one. OK, I haven't heard this argument
then.

3. Let us ignore that the same air inside the wing pushes down on the
overside of bottom part of wing.
4. The difference in pressure against the underside of the top wing
on
the inside of wing and top of wing on outside, is what gives plane
lift.

You can consider that last just a definition of lift. You
won't get lift unless the upward forces are stronger than
then downward forces.

Note that they ignore the pressure inside the wing that pushes
downward on the wing.

A wing doesn't need to be hollow to fly.

I am trying to convince them that, if there is air on the inside of
the wing, it pushes against all sides of the inside of the wing,
including both top underside and bottom overside, and thereby
nullifying any effect it would have on the wing. Lift is caused by a
difference in pressure between the underside of the bottom of the
wing, and the overside of the top of the wing.

I count 8-9 people in the group who are utterly convinced that I am
inept at physics, mathematics, etc.

Note that some of these people have been flying aircraft for years,
even decades, while I am still a student pilot.

Comments from anyone who knows physics welcome.

As I said, I lean toward the angle-of-attack arguments now. Take
a flat rectangle, tilt it into the wind. The wind blows against the
front which is also the bottom, not the back/top. So the
forces are on the bottom.

Why does that translate into lift? I forget the exact arguments
but from first principles if the effect is to change the direction
of the incoming air molecules, then by conservation of
momentum that translates into equal and opposite change
of momentum of the surface, i.e. pressure with an upward
component.

- Randy



Well, thanks be to god that that';s been authoritatively setttled.


Bertie