Airplane Pilot's As Physicists

On Oct 10, 10:25 am, wrote:
This is exactly how I see this as well. This character and his puppets
are playing out a conversation with themselves (one person) designed to
capitalize on the few simple misconceptions concerning Bernoulli that
are common knowledge among the professional aviation community and have
been "corrected" years ago.
Unfortunately for this forum, there are still a few old textbooks
hanging around out there reflecting these misconceptions. This, coupled
with the fact that there are individual pilots out here (from the GA
community mostly) who apparently lack the formal physics knowledge to
take on someone whose sole intent is to discredit them by cleverly using
the remaining confusion in the community concerning Bernoulli against them.
The REAL rub in this situation is that the idiot doing this, from what I
have seen in his posting, has very little knowledge HIMSELF about the
lift issue and is totally wrong in critical areas of his argument.
It's an unfortunate situation designed by a person who seems to pleasure
himself by what he's doing.
Personally I wouldn't give this idiot the time of day. His understanding
of Bernoulli is much worse than those with whom he has engaged. Those
who are on to him he avoids, only taking glancing shots at them knowing
he won't be answered directly.
It's a shame really....but what the hell, it's Usenet!!
:-)))

--
Dudley Henriques

I haven't minded taking the bait. The process has
pointed out many good websites we can use in instruction, and has
forced a review of some basic principles. Got to find the silver
lining, right?

Right.

Nothing wrong with a little discussion.

-Le Chaud Lapin-

Le Chaud Lapin wrote:

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.

1) Acrobatic airplane wings are essentially symmetric in
cross-section. They fly equally well rightside-up or inverted. Angle
of attack is important.

2) Bernoulli's law is strictly a 2-D analysis.

3) Dr. Penelope Smith rigorously derived vortex shedding is a major
lift component in 3-D. Don't be Cessna behind a jumbo.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/lajos.htm#a2

Uncle Al wrote in
:

Le Chaud Lapin wrote:

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...wse_frm/thread
/b85a49e900a0c791/bb11fa289cd7864a#bb11fa289cd7864a

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.

1) Acrobatic airplane wings are essentially symmetric in
cross-section. They fly equally well rightside-up or inverted. Angle
of attack is important.

2) Bernoulli's law is strictly a 2-D analysis.

3) Dr. Penelope Smith rigorously derived vortex shedding is a major
lift component in 3-D. Don't be Cessna behind a jumbo.


Wow, you are a cut and paste genius Anthony.


Bertie

Le Chaud Lapin wrote in
ups.com:

On Oct 10, 10:25 am, wrote:
This is exactly how I see this as well. This character and his
puppets are playing out a conversation with themselves (one person)
designed to capitalize on the few simple misconceptions concerning
Bernoulli that are common knowledge among the professional aviation
community and have been "corrected" years ago.
Unfortunately for this forum, there are still a few old textbooks
hanging around out there reflecting these misconceptions. This,
coupled with the fact that there are individual pilots out here
(from the GA community mostly) who apparently lack the formal
physics knowledge to take on someone whose sole intent is to
discredit them by cleverly using the remaining confusion in the
community concerning Bernoulli against them. The REAL rub in this
situation is that the idiot doing this, from what I have seen in
his posting, has very little knowledge HIMSELF about the lift issue
and is totally wrong in critical areas of his argument. It's an
unfortunate situation designed by a person who seems to pleasure
himself by what he's doing.
Personally I wouldn't give this idiot the time of day. His
understanding of Bernoulli is much worse than those with whom he
has engaged. Those who are on to him he avoids, only taking
glancing shots at them knowing he won't be answered directly.
It's a shame really....but what the hell, it's Usenet!!
:-)))

--
Dudley Henriques

I haven't minded taking the bait. The process has
pointed out many good websites we can use in instruction, and has
forced a review of some basic principles. Got to find the silver
lining, right?

Right.

Nothing wrong with a little discussion.



You're not intersted in discussion, fjukkwit


Bertie

Uncle Al wrote in
:

Le Chaud Lapin wrote:

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...wse_frm/thread
/b85a49e900a0c791/bb11fa289cd7864a#bb11fa289cd7864a

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.

1) Acrobatic airplane wings are essentially symmetric in
cross-section. They fly equally well rightside-up or inverted. Angle
of attack is important.

2) Bernoulli's law is strictly a 2-D analysis.

3) Dr. Penelope Smith rigorously derived vortex shedding is a major
lift component in 3-D. Don't be Cessna behind a jumbo.



Oops, sorry, friendly fire.


Bertie

On Oct 10, 7:06 am, Bertie the Bunyip wrote:
"CWatters" wrote :

"Mxsmanic" wrote in message
.. .
The essential feature of an airfoil is that it twists the flow of
air as
it
passes (or as the airfoil passes through still air, which is
equivalent,
and
that's how it works in airplanes). The air is accelerated downward,
and
this
engenders an equal and opposite force that is lift.

Nope. That wouldn't explain how wing sections for tailless planes
work. The sections for those curve up towards the trailing edge. The
leading edge produces lift but the trailing edge produces a _downward_
force to counter the pitching moment. Example section...

http://www.desktopaero.com/appliedae...mages/image13_
43.
gif

Good point.

The porblem with this guy is (and it's just one guy with a handful of
sockpuppets) is that he ses some discrepencies in how bernoulli is
explained and has concluded that it must be incorrect since there is
"disagreement amongst the experts"

A good analogy here would be the eeedjit creationists who grasp at the
straws presented by the minor scuffles occuring within the evolutionary
sciences.

Bertie

Obviously, pilots AND the airplanes they fly are just plain too
stoopid to fall.

"Scientists Refute Gravity with New "Intelligent Falling" Theory"
http://www.theonion.com/news/index.php?issue=4133&n=2

Jim Deutch (JimboCat)
--
The Japanese tried coating airplane wings with teflon, but could never
come up with a good nonstick flying plan.

JimboCat wrote in
ups.com:

On Oct 10, 7:06 am, Bertie the Bunyip wrote:
"CWatters" wrote
:

"Mxsmanic" wrote in message
.. .
The essential feature of an airfoil is that it twists the flow of
air as
it
passes (or as the airfoil passes through still air, which is
equivalent,
and
that's how it works in airplanes). The air is accelerated
downward, and
this
engenders an equal and opposite force that is lift.

Nope. That wouldn't explain how wing sections for tailless planes
work. The sections for those curve up towards the trailing edge.
The leading edge produces lift but the trailing edge produces a
_downward_ force to counter the pitching moment. Example section...

http://www.desktopaero.com/appliedae...mages/image13_
43.
gif

Good point.

The porblem with this guy is (and it's just one guy with a handful of
sockpuppets) is that he ses some discrepencies in how bernoulli is
explained and has concluded that it must be incorrect since there is
"disagreement amongst the experts"

A good analogy here would be the eeedjit creationists who grasp at
the straws presented by the minor scuffles occuring within the
evolutionary sciences.

Bertie

Obviously, pilots AND the airplanes they fly are just plain too
stoopid to fall.



This is it.

A bit like the high rise housing in Monty Python that existed only
because he residents had been hypnotised into believeing they did.


Bertie

On Oct 9, 4:08 pm, Le Chaud Lapin wrote:
Comments from anyone who knows physics welcome.

Hee, hee! You obviously don't know sci.physics!

Jim Deutch (JimboCat)
--
"The world is raining knowledge and most
folks use their soupbowls as rain bonnets."
-- Uncle Al

On Oct 9, 6:15 pm, Ray Vickson wrote:
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.

Probably true, in large part anyway. Just consider that aerobatics
pilots can fly their planes upside-down over considerable distances.
If Bernoulli were the sole factor this couldn't happen.

R.G. Vickson

It doesn't have to be either-or. Both Bernoulli and angle of attack
are at work in generating lift. Both the top and bottom surfaces of
the wing contribute. The fact that aerobatic planes can be flown
upside down shows that if you take a normal airfoil and fly it upside
down at the right angle of attack, it will still generate lift. But
unless it has a symmetric airfoil, it will be a lot less efficient
when it is operated upside down. This is because the when it is
upside down, the top surface of the wing is flat rather than curved,
and hence you lose a lot of the lift which this surface generates when
it is rightside up. This is why many aerobatic planes have symmetric
airfoils. A symmetric airfoil works well upside down because it still
has a curved surface on top to help generate lift.

Uncle Al wrote:
2) Bernoulli's law is strictly a 2-D analysis.

Are you sure? I ask because I know the application of Bernoulli's theorem
to airfoils is typically restricted to 2-D and wondering if that is what
you meant. Otherwise there doesn't appear to be any dimensional assumption
in the theory itself or its derivation. Here's one typical presentation of
Bernoulli's theorem:

"In the steady motion of an inviscid fluid the quantity

p/rho + K

is constant along a streamline, where p is the pressure, rho is the density
and K is the energy per unit mass of fluid."

And the definition of streamline also appears void of dimensional
restriction:

"A line drawn in the fluid so that its tangent at each point is in the
direction of the fluid velocity at that point is called a streamline."

Both quotes from "Theoretical Aerodynamics" by L. M. Milne-Thomson.

So unless I'm mistaken (and I could be) it appears that Bernoulli's
theorem:
1) Applies to compressible or incompressible fluids.
2) Does not necessarily apply to viscous fluid flows.
3) Does not necessarily apply to turbulent flow (it's not "steady motion".)
4) Does not itself define the flow streamlines.
5) Is not restricted to 1 or 2 dimensional analysis.