visualisation of the lift distribution over a wing

Alan Baker wrote:
In article ,
brian whatcott wrote:

Stealth Pilot wrote:
/snip/ it is the air below pushing
you up that lifts the wing.
Stealth Pilot
In most circumstances, suction on the upper surface contributes about
2/3 rds of the lift, and pressure on the lower surface contributes about
1/3 rd.
That's one reason which rib stitching for rag wings is a biggy.

Brian W

Ummmm...

It sort of depends what you mean.

If you mean that suction is actually providing an upward force, you're
quite mistaken.

If you mean that the difference in pressure between upper and lower
surfaces is 2/3 the result of lower pressure on the upper surface, then
you might be right. I don't know.


Interesting comment: what would YOU call it when the fabric on the upper
wing surface wants to pull away from the ribs?

Brian W

brian whatcott wrote:
Alan Baker wrote:
In article ,
brian whatcott wrote:

Stealth Pilot wrote:
/snip/ it is the air below pushing
you up that lifts the wing.
Stealth Pilot
In most circumstances, suction on the upper surface contributes about
2/3 rds of the lift, and pressure on the lower surface contributes
about 1/3 rd.
That's one reason which rib stitching for rag wings is a biggy.

Brian W

Ummmm...

It sort of depends what you mean.

If you mean that suction is actually providing an upward force, you're
quite mistaken.

If you mean that the difference in pressure between upper and lower
surfaces is 2/3 the result of lower pressure on the upper surface,
then you might be right. I don't know.


Interesting comment: what would YOU call it when the fabric on the upper
wing surface wants to pull away from the ribs?

Brian W

It's the "wind" blowing through the bottom surface, inflating the wing
like a balloon

In article ,
brian whatcott wrote:

Alan Baker wrote:
In article ,
brian whatcott wrote:

Stealth Pilot wrote:
/snip/ it is the air below pushing
you up that lifts the wing.
Stealth Pilot
In most circumstances, suction on the upper surface contributes about
2/3 rds of the lift, and pressure on the lower surface contributes about
1/3 rd.
That's one reason which rib stitching for rag wings is a biggy.

Brian W

Ummmm...

It sort of depends what you mean.

If you mean that suction is actually providing an upward force, you're
quite mistaken.

If you mean that the difference in pressure between upper and lower
surfaces is 2/3 the result of lower pressure on the upper surface, then
you might be right. I don't know.


Interesting comment: what would YOU call it when the fabric on the upper
wing surface wants to pull away from the ribs?

Air pressure from inside the wing pushing up on it more than the air
above is pushing down...

--
Alan Baker
Vancouver, British Columbia
http://gallery.me.com/alangbaker/100008/DSCF0162/web.jpg

"Alan Baker" wrote

Air pressure from inside the wing pushing up on it more than the air
above is pushing down...

I hope you are pulling someone's leg, and that your are not that inept in
the field of aerodynamics and physics.
--
Jim in NC

In article ,
"Morgans" wrote:

"Alan Baker" wrote

Air pressure from inside the wing pushing up on it more than the air
above is pushing down...

I hope you are pulling someone's leg, and that your are not that inept in
the field of aerodynamics and physics.

No, I'm quite serious.

The reduction in *pressure* on the upper surface of the wing cannot
produce any force except downward. A perfect vacuum over the entire
upper surface wouldn't produce any upward force, but simply *zero*
force; allowing the upward force on the lower surface to act alone.

Anyone who thinks that the pressure of a fluid on a surface can act in
any direction but towards the surface is simply wrong.

--
Alan Baker
Vancouver, British Columbia
http://gallery.me.com/alangbaker/100008/DSCF0162/web.jpg

"Alan Baker" wrote

Anyone who thinks that the pressure of a fluid on a surface can act in
any direction but towards the surface is simply wrong.

I see. You are not lookng at the wing as a system, but taking an
observation at one point only, without reguard to what is happening around
it.

Point made.
--
Jim in NC

Morgans wrote:
"Alan Baker" wrote
Anyone who thinks that the pressure of a fluid on a surface can act in
any direction but towards the surface is simply wrong.

I see. You are not lookng at the wing as a system, but taking an
observation at one point only, without reguard to what is happening around
it.

Point made.

He looked inside the wing, at the entire upper surface, at the lower
surface... that pretty much covers most of it. Air can't be in tension.

Beryl wrote:
Air can't be in tension.

If it had a stressful day it might become tense. Air can be under a lot of
pressure at times, and work can cause it to get hot. Put under too much
pressure, air can blow a gasket.

That's why it's best to let air blow off steam after a hard day at work and
maybe offer it a smoke with a gin and tonic to cool off:

http://www.bobblum.com/Images/Humor%.../subgenius.jpg

"Beryl" wrote

He looked inside the wing, at the entire upper surface, at the lower
surface... that pretty much covers most of it. Air can't be in tension.

Yes, but the person that observed that the pressure on the bottom was one
third responsible (for lift) and the low pressure on top was responsible for
two thirds of the lift is also correct, when you look at the wing as a whole
system, even if those fractions are approximate.

I think his view of individual points of observations are splitting
toadstools.

But that is my opinion, and like everyone, we all have but-holes and
opinions.
--
Jim in NC

In article ,
"Morgans" wrote:

"Alan Baker" wrote

Anyone who thinks that the pressure of a fluid on a surface can act in
any direction but towards the surface is simply wrong.

I see. You are not lookng at the wing as a system, but taking an
observation at one point only, without reguard to what is happening around
it.

Point made.

Nope.

I'm making the point that the upper surface contributes absolutely *no*
lifting force.

None.

Zero.

In fact, it provides a downward force. Every time.

--
Alan Baker
Vancouver, British Columbia
http://gallery.me.com/alangbaker/100008/DSCF0162/web.jpg