Abstract:

ESDU 78009 derives, from simple sweep laws and the concept of the equivalence of two- and three-dimensional flows, a framework in the form of equations relating lift, freestream Mach number, and the growth of wdave drag for the wing to those same quantities for the aerofoil basic to the wing. There is no universal geometric relationship that will ensure that the wing reproduces the aerodynamic characteristics of its basic aerofoil and so values of some of the terms involved in the framework have to be determined by its user, but guidance on appropriate choices is given. There are three uses for the framework: to reconcile the known drag-rise characteristics of a wing with those of its basic aerofoil, to estimate the performance of an improved wing design, and to provide a performance target for a new wing. A worked example illustrates the use of the method.