On 27 Jan 2007 17:06:37 -0800, wrote:

....
A flat surface, AB, is moving through the air, with the surface
exactly perpendicular to the direction of movement. In the graphic
below, the surface is moving downward. Point X is behind and slightly
to the inside of B.

X

A___________________________________B
|
|
V

As the surface moves through the air, the air "curls" around B and
hits X. To help eliminate this, we need to change the angle of
surface AB so that it deflects the oncoming air outwards and away from
X. In other words we need to move B "upwards" in the graphic above.

The question is, how many degrees does AB need to move to produce the
MAXIMUM amount of air deflection?

What happens at the A end is irrelevant. B really just pivots around
it.

For what it's worth, this is a fairly thin surface, about 1/4" thick....
Bill S.

Airfoils develop max lift at an agle of attack around 15 degrees

Beyond that drag starts rising dramatically, though lift does not
vanish until much higher angles often.

In your diagram line AB would be 15 degrees away from vertical.
But airfoils expect air to flow along both sides - so if you are
masking the side where X lives, ignore this note.

Brian Whatcott Altus OK