On Oct 7, 11:58 pm, Le Chaud Lapin wrote:
On Oct 7, 11:02 pm, flightoffancy wrote:
I did notice the turning. The article is claiming that the upper
surface of the wing "turns" the upper flow.

Link:http://www.grc.nasa.gov/WWW/K-12/airplane/right2.html

I must admit that I am having problems with this explanation. It is
extremely vague? What is the turning? How, exactly, does the wing
"turn" the flow. The air is made up of molecules. If it is upper
surface of the wing that is turning does air molecules so that they
have a velocity component that is downward, how is this happening?
Since when, could one body, A, of any kind, that does not involve
gravitational or electrostatic fields, induce another body B, to move
in a direction that has a component vector that is aimed directly at
B?

I just re-read the link above very carefully, and unless I am
mistaken, there is a *huge* amount of hand-waving going on here too.
Sigh.

"Turning" a flow? What would Newton say. It's magic.

Yes, we all know that F=ma, and "a" is the time derivative of
velocity, a = dv/dt, and that v has a magnitude and a direction, and
that if you change either magnitude or direction, you have a
force...that's all fine...

They do not specify how the wing turns the air. They show a picture
of air flowing backward on top of a sligtly-angled wing. Then they
write:

"For a body immersed in a moving fluid, the fluid remains in contact
with the surface of the body. If the body is shaped, moved, or
inclined in such a way as to produce a net deflection or turning of
the flow, the local velocity is changed in magnitude, direction, or
both. Changing the velocity creates a net force on the body. It is
very important to note that the turning of the fluid occurs because
the molecules of the fluid stay in contact with the solid body since
the molecules are free to move."

"the molecules stay in contact with the solid body"...?????????????

Why?

What incentive do the molecules have to stay in contact with the solid
body? Is there a sign on top of the wing that reads:

**** NOTE: ALL MOLECULES, YOU ARE HEREBY ORDERED TO STAY AS CLOSE TO
ME AS POSSIBLE. ****

Are there little molecule-sized pina coladas on top of the wing
waiting for the molecules to drink?

Even if there is a thin layer of air remaining in contact with the
wing for mysterious, magical reasons, what about the layers above it?
What incentive do those layers have "try and stay in contact with the
wing"?

-Le Chaud Lapin-