Abstract:
Camber and twist is applied to the problem of reducing the drag due to incidence, of thin triangular or swept-back wings, at supersonic speeds, with subsonic leading edges and supersonic or sonic trailing edges. Two cases are considered: (i) with leading-edge suction forces ignored, (ii) with leading-edge suction forces included. It is found that twist, especially towards the wing tips, is more effective in reducing drag, for given lift, for the larger values of tan γ/tan μ, where γ is the semi-apex-angle and μ is the Mach angle, and that camber is more effective for the smaller values, though, in general, the best results are obtained by a suitable combination of camber and twist. For triangular wings, with suction ignored, the maximum percentage drag reduction varies from about 10 per cent (for sonic leading edges) to 50 per cent (for very slender plan-forms) and, if suction forces are included, from zero (for very slender plan-forms) to about 10 per cent (when the leading edges are sonic). The effect of the swept-back trailing edge is, in general, to increase the maximum percentage drag reduction for given lift if suction forces are ignored; but to decrease the maximum reduction for smaller values of tan γ/tan μ, and to increase the maximum reduction for values of tan γ/tan μ near to one, if suction forces are included.
