AERODYNAMIC COEFFICIENTS OF A THIN WING WITH ELLIPTIC PLANFORM IN UNSTEADY MOTION.

An analytic solution is presented for the linearized lifting-surface problem of a thin wing with elliptic planform in unsteady incompressible flow. The analysis is based on expansion of the acceleration potential in infinite series of ellipsoidal harmonics, and extends the steady analysis recently developed by the authors, to the unsteady flow regime. Explicit expressions are obtained for both the starting lift in the case of impulsive acceleration and for the lift due to constant acceleration. The exact solution thus obtained is valid for the whole range of aspect ratios. The analytic result for the starting lift may be treated as new generalization of the classical Wagner's two-dimensional solution for planforms of finite aspect ratios.