Backwash Causes Lift?

Mxsmanic wrote in
:

Le Chaud Lapin writes:

Obviously, any air above the wing can only result in a force downward
on top of the wing. The only force causing the plane to want to move
upward comes from beneath the wing. The effect of any air above the
wing is to cause rarefication above the wing, resulting in lower
pressure, thereby giving the 14.7lbs/in^2 (plus) to do its work. That
"reaction" coming from downward movement of air seems just plain
silly to me.

Lift is a reaction to the force required to push air downward behind
the wing (downwash). How the air gets pushed downward is not very
important. The wing twists air into a downwash as it passes through
it, leaving a swath of air moving gently downward behind it. The
force required to do this engenders an equal and opposite force that
is lift. Lift accelerates the wing upward, counteracting gravity.
The wing accelerates a large mass of air downward.

I am also inclined to take issue with the explanations of
Bernouilli's Principle which I see often in the literature, but
that's a different subject. [Note, I don't doubt Bernouilli's
Principle, I just think there is more to it than the way it is being
described in context of flying.]

There are a lot of different ways to examine and describe the
aerodynamics of lift. It boils down to accelerating one mass (a mass
of air) downward, which engenders another acceleration of another mass
(the wing, and anything to which it is attached) upward. Any flat
surface moving relative to the air with a positive angle of attack
below the stall angle will generate lift.


Nope.


Bertie