Downwash distribution behind a wing with an angle of attack discontinuity at supersonic speeds

Abstract

Investigation of the downwash field behind a wing with an angle of attack discontinuity at supersonic speeds by use of linearized conical flow theory has shown the downwash to be of finite magnitude at all points in and behind the plane of the wing. The downwash at more than five chord lengths behind the wing was found to asymptotically approach the value of downwash calculated in the Trefftz plane. Behind the wing and within the span that is determined by the intersection of the Mach cones from the leading edge with the trailing edge, an unexplicable action of the downwash was found to exist. It was found that at the trailing edge the downwash was a 100 percent of that on the wing surface. At two chord lengths, the downwash was 83 percent. Upon moving aft, it was found that the downwash increased in magnitude and that at 10 chord lengths, it asymptotically approached the value at the Trefftz plane, namely 100 percent again. By considering an idealized missile configuration, it was found that roll reversal was possible. The possibility of reversal was found to be almost entirely dependent upon the location of the control lifting surfaces with respect to one another. A brief reference to the sidewash field was made, since the values of sidewash were a natural outgrowth of the solution of the downwash field in the Trefftz plane. An elementary consideration of the sidewash field also showed a contribution to an induced rolling moment that tends to produce roll reversal.