Variable aerodynamic compression flaps

Claim 1

In an airplane a wing having a lower surface which in horizontal flight of the airplane extends generally horizontally, trailing edge unpowered geometric aerodynamic compression flap means pivoted on said wing, means in said flap means providing a rearwardly convergent channel of fixed geometry for geometrically compressing exterior air, defined on its upper and lower sides by upper and lower predominantly convergent surfaces extending therethrough for at least most of the entire width thereof from front to rear and having an intake adjacent the forward end of the flap means, and an always open exit of fixed depth in a rearward portion of the flap means wherein the compression ratio K of said channel is varied and determined according to the formula K = to/tj where to = depth of intake tj = depth of exit, and means for varying K between substantially zero and maximum values by closing and opening the intake, including means for pivoting said flap means about an axis which is fixed with respect to the wing between elevated and depressed conditions, said wing, flap means and channel being characterized by the fact that in the elevated position of the flap, said intake is disposed behind the trailing edge of the wing and the latter at least partly masks the intake, and being further characterized by the fact that the upper surface of the channel at the intake is substantially aligned with the lower surface of the wing in a depressed position of the flap means, so that air flowing along the lower surface of the wing enters the channel intake with no substantial angular change in direction at said entry, and characterized further than in the depressed position of the flap means the exit is directed downwardly and rearwardly with respect to the lower surface of the wing.