How wings really work. Youtube video show all.

[groundfx]

They say a picture is worth a thousand works. I think this video is worth much more than that!

The pulsed smoke section is priceless, it shows airspeed over and under the airfoil, this should settle some arguments. ;)

http://www.youtube.com/watch?v=6UlsArvbTeo

[Brandano]

the position of the stagnation point on the leading edge at high AOA's is also quite interesting. Nice movie indeed. I am quite surprised by how large the AOA can become before complete flow separation. Any idea in what approximate Reynold range was the wind tunnel operating?

[nmasters]

Yeah, thats a good one. Looking for the pearls among all the garbage on youtube can be rewarding. Here's another flow study with an interesting separation segment, this time it's the vortex that's responsible for spoiler lag.

--Norm
http://www.youtube.com/watch?v=ouF9Xkoi3uk

[Texas Buzzard]

From these videos we can see that what was said/taught about how an airplane wing develops LIFT 50 years ago parallels what we see in these modern videos.

Lately the "old" explanation has been attacked by some practitioners. Looks like the basic explanation still holds to be logical. :) :)

[MarkusN]

From these videos we can see that what was said/taught about how an airplane wing develops LIFT 50 years ago parallels what we see in these modern videos.
If you were referring to that: In its pure form the run length explanation is rubbish. According to that a flat plate can't fly, a cambered airfoil can't fly upside down, the highest lift airfoil is the shoesole design, undercambered airfoils have lower lift than flat bottomed ones and many more. I have heard (pure anectdotal evidence, so don't quote me) even Einstein once came up with a design of an airfoil with wavy top surface for a high lift airfoil because of that explanation.

It does have some merit in explaining why airfoils look how they look, but even at that it fails as soon as you go into the finer details.


As for the Bernoulli / Newton bashing:

For me I have come to the conclusion that here there is a fundamental difference between two dimensional flow, in which lift is usually expained in a theoretical way with potential theory (which is closely related to, but not precisely, Bernoulli), and the real life problem of a three dimensional wing. The two dimensional flow is partly an aerostatic problem, as the flow is contained along the axis of the wing. Pressure and lift can be retained without net downward acceleration of air masses. That is no longer true for the three dimensional wing. Here pressure and lift need the inertial forces of downwards accelerated air opposing to hold equilibrum, thus Newton.

BTW, any self respecting Newtonian won't deny that air flows faster over the top of the wing. It's the cause / effect chain that they attack.

[JetPlaneFlyer]

From these videos we can see that what was said/taught about how an airplane wing develops LIFT 50 years ago parallels what we see in these modern videos.

Lately the "old" explanation has been attacked by some practitioners. Looks like the basic explanation still holds to be logical. :) :)

What do you mean by the 'old' explanation Buzzard?

If you mean the old 'equal time of transit' rubbish about the air having to move faster over the longer top surface so it can arrive at the TE at the same time as the air on the underside... The video proves this to be false. Look at the slow motion pulse smoke clip, it very clearly shows that the air on top arrives at the TE long before the air on the underside.

[Texas Buzzard]

JetPlaneFlier said, "What do you mean by the 'old' explanation Buzzard?

If you mean the old 'equal time of transit' rubbish about the air having to move faster over the longer top surface so it can arrive at the TE at the same time as the air on the underside... The video proves this to be false. Look at the slow motion pulse smoke clip, it very clearly shows that the air on top arrives at the TE long before the air on the underside."
.................................................

No, I do not mean the "equal time of transit". No, the air moving over the top surface in the videos arrives at the TE a bit sooner than the air flowing across the bottom surface. This has to mean that the air moving over the top surface IS MOVING FASTER than the air over the lower surface. This is not a mystery.

We know that when air is made to move faster in a venturi, a tube or over a surface the pressure of the air will decrease. THIS is basically what I meant by the OLD EXPLANATION. ( circa 1930's to 1960's)

IMO, the video shows the air over the top surface is moving faster than the air over the lower surface. This is consistant with the OLD EXPLANATION.
Refer to the work at the Univ. of Illinois wind tunnel at Urbana. Dr. Mike is the director.

[nmasters]

At the college level it hasn't changed much since Ludwig Prandtl was alive. Just that a lot of modelers couldn't grow up and set aside the BS their grade school teachers told them. Let's not get into the origine of lift argument. Here, look at some more cool videos: http://www-mdp.eng.cam.ac.uk/library/enginfo/aerothermal_dvd_only/aero/vis/index.html

--Norm

[Brandano]

lift happens because of reaction. Some air is moved downwards, and the wing is moved upwards by reaction. How this happens is the only thing that people seem to fail to grasp. The fact that there is less pressure on the top of the wing than under it means that there is more air under the wing than over it, it has effectively been moved downwards. And this happens even before the wing has actually gone through it, how odd.... If the only scope of a wing was that of deflecting air down as if it was a bunch of tennis balls, why would people bother so much about studying the upper profile of wings? And how come that spoilers are so effective at killing lift? standard airbrakes on the fuselage are easier to make, if the only reason for spoilers was to increase drag then going the complex route and building them in an already complex wing would be pointless. Some planes even use spoilers for roll input, and they work really well for that, see for example the Panavia Tornado.

[Wufnu]

Air does alot of crazy things. Ask anyone that hasn't taken compressible flow what they think happens to the air velocity, after the throat where the velocity is the fluids speed of sound, in an expanding diameter tube.

"It slows down!"

Get ready for a big surprise. Gasses are weird =/

I really like these videos posted so far. The pictures, too. Maybe it's the geek in me but if I had a setup like that at home I think I would play with it all day long.