Airplane Pilot's As Physicists

Hi All,

There is a long discussion ongoing in rec.aviation.piloting about what
causes lift on a plane. You can read from the link below. Please
note that about 80% of the post are mostly ad hominem attacks and
should be ignored. There are some small bits of real discussion.

http://groups.google.com/group/rec.a...11fa289cd7864a

I am an electrical engineer with experience in analag design and
software, with math and physics background that you would expect of an
electrical engineer.

There are many points made in the discussion, but I would like to
focus on one in particular for the sake of progress.

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 .
3. Let us ignore that the same air inside the wing pushes down on the
overside of bottom part of wing.
3. 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.

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

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.

-Le Chaud Lapin-

Le Chaud Lapin wrote in
ps.com:

Hi All,

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


No, there isn't. There are people who know perfectly well how it works
trying to tell a ccouple of k00ks who think they know


Bertie

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

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

On Oct 9, 4:25 pm, Bertie the Bunyip wrote:
Randy Poe wrote groups.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.
[snip]

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

"Authoritatively"? Can you read? Can you read the
part where I said "I'm no expert" and where I said that
I was convinced by other people?

- Randy

Randy Poe wrote in
ps.com:

On Oct 9, 4:25 pm, Bertie the Bunyip wrote:
Randy Poe wrote
groups.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.
[snip]

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

"Authoritatively"? Can you read? Can you read the
part where I said "I'm no expert" and where I said that
I was convinced by other people?


Oow, you ned a sarcasm detector. I can put one up on Ebay for you if you
like.


Bertie

On Oct 9, 3:22 pm, Randy Poe wrote:
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.

Thanks Randy,

But before we talk about what causes lift on the plane, we should
clear up the basic physics 1st. Note that what I have described above
has nothing to do with airplanes really.

If you read carefully, the premise of what they are saying is that, if
you have, for example, a sealed jar with air in it, you are permitted
to consider the air on the _inside_ of the jar, pushing up on the lid
as contributing to a force to lift the jar off the ground, but you are
not allowed to consider the air on the _inside_ of the jar, pushing
down on the jar un the upper surface of the bottom of the jar.

-Le Chaud Lapin-

Le Chaud Lapin wrote in
ups.com:

On Oct 9, 3:22 pm, Randy Poe wrote:
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.

Thanks Randy,

But before we talk about what causes lift on the plane, we should
clear up the basic physics 1st. Note that what I have described above
has nothing to do with airplanes really.

If you read carefully, the premise of what they are saying is that, if
you have, for example, a sealed jar with air in it, you are permitted
to consider the air on the _inside_ of the jar, pushing up on the lid
as contributing to a force to lift the jar off the ground, but you are
not allowed to consider the air on the _inside_ of the jar, pushing
down on the jar un the upper surface of the bottom of the jar.



Oh for ****'s sake.

You push on something it moves, right?

Everone already knows that, Stephen hawkings.


While you're trying to agitate in a physics froup why don;'t you ask
them how it's physically possible to get your head that far up your own
ass.

Bertie

Le Chaud Lapin writes:

If you read carefully, the premise of what they are saying is that, if
you have, for example, a sealed jar with air in it, you are permitted
to consider the air on the _inside_ of the jar, pushing up on the lid
as contributing to a force to lift the jar off the ground, but you are
not allowed to consider the air on the _inside_ of the jar, pushing
down on the jar un the upper surface of the bottom of the jar.

The atmosphere is not a sealed jar. The source of air pressure in the
atmosphere is gravity, not confinement and kinetic energy.

Mxsmanic wrote in
:

Le Chaud Lapin writes:

If you read carefully, the premise of what they are saying is that, if
you have, for example, a sealed jar with air in it, you are permitted
to consider the air on the _inside_ of the jar, pushing up on the lid
as contributing to a force to lift the jar off the ground, but you are
not allowed to consider the air on the _inside_ of the jar, pushing
down on the jar un the upper surface of the bottom of the jar.

The atmosphere is not a sealed jar. The source of air pressure in the
atmosphere is gravity, not confinement and kinetic energy.


You are an idiot.


Bertie