The shape of the centre part of a swept-back wing with a required load distribution

Abstract

A method is developed for designing the centre portion of a cambered and twisted swept-back wing to have the same chordwise load distribution at all spanwise stations. For this purpose the downwash field induced by a doublet distribution of constant spanwise strength in the chordal plane of a constant-chord wing is determined for incompressible, sonic and supersonic main-stream flow. Since the downwash has a logarithmic singularity at the centre section in the chordal plane itself, an approximate method is suggested to satisfy the boundary condition at the surface of the thick wing. Numerical examples illustrate the influence of the angle of sweep, the wing thickness and the load distribution. They show in particular that the required shape does not vary much with Mach number. A relatively rapid change of twist and camber with the spanwise distance from the centre section is required as shown by calculated results for sonic flow. There is some reason for using the camber and twist designed for the centre section of the isolated wing also for wing-fuselage junctions.