Velocity distribution on straight and swept-back wings of small thickness and infinite aspect ratio at zero incidence

Abstract

A solution by H. Ludwieg, giving the velocity distribution in tile central section of a thin swept-back wing of infinite aspect ratio with a biconvex profile at zero incidence, has been found erroneous. In connection with this problem, the approximate method of sources and sinks for determining velocity distribution on straight and swept-back wings is critically examined, its limitations established, and proper ways of its application to threedimensional problems indicated. A correct solution of Ludwieg's problem is found, and generalized to give the velocity distribution over the entire wing. The method is further extended to cover a wide class of thin symmetrical wing profiles, those with rounded leading edge being, however, often intractable by this particular method. The ultimate purpose of the investigation is to provide a reliable basis for determining the critical Mach number for swept-back wings. Further work is needed to embrace wings of finite aspect ratio and tapered wings, in particular delta-wings. The method seems adequate to deal with these more complex cases.