> And someone tell us how to explain how circulation induces lift
> to a budding pilot.
Track the path of a single air particle as the airfoil approaches and
p*****. It will move, roughly, in a circle (aka circulation). A particle
going over the wing will initially move forward and up due to positive
pressure from the leading edge, then get pulled back and down along the
top
surface. A particle going under will go the opposite direction. However,
the particles won't end up where they started...they'll both be lower than
they were initially (assuming positive angle of attack). Net result is
downward momentum transfer to the air, which results in an upward force on
the wing (lift).
Any shape which imparts downward momentum to the airstream will generate
lift. Airfoil design is all about getting the maximum lift for the drag
and
avoiding problematic flows (separation, shocks, etc.)
> Oh, yeah, FWIW, a supercritical wing produces lift because it's at an
> angle of attack, just like a symmetrical or plane surface airfoil is to
> develop lift.
True, because a supercritical wing gives imparts momentum to the airstream
just like a flat plate or normal airfoil. The major point with a
supercritical thing is that it will continue to do that efficiently (with
low drag) at a higher speed than a conventional airfoil.
Tom.
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