A Linear Perturbation Method for Stability and Flutter Calculations on Hypersonic Bodies

Abstract

The equations governing linear perturbations in three space variables and time of steady supersonic potential flow past bodies of revolution are derived. The equations are referred to a characteristic coordinate system, and a general numerical process of solution is described. The assumption of potential flow simplifies the theory considerably and is justified in most flutter calculations and in estimating the contribution to stability derivatives from the rear part of a body. However, there is no obstacle in principle to generalizing the technique to apply to nonisentropic flow fields. As an example, to represent the contribution of a typical hypersonic afterbody, the static stability derivatives associated with the exterior surface of a converging conical duct are calculated. Dynamic stability derivatives can be found by a simple extension of this calculation.