Supersonic flutter of aeroelastically tailored oblique wings

Abstract

Renewed interest in oblique wing aircraft has created curiosity about the possible use of aeroelastic tailoring to enhance its aeroelastic stability. This paper examines the flutter characteristics of an idealized, advanced composite, oblique wing configuration operating at supersonic speeds. The theoretical model consists of a uniform property wing with beamlike flexural and torsional flexibility as well as bend-twist deformation cross-coupling. The wing is free to roll unrestrained about a streamwise roll axis. Quasisteady, linearized, supersonic aerodynamic theory is used to describe the deformation-dependent aerodynamic forces. The effects of characteristic inertial, aerodynamic, and structural parameters on flutter behavior are surveyed. Among these parameters are the following: wing aspect ratio; mass ratio; Mach number; fundamental bending-torsion frequency ratio; bend-twist deformation coupling; wing sweep angle; and the wing-to-fuselage roll mass moment of inertia ratio. It is shown that when tailoring is used to increase the stability of a body-freedom mode, the result is a reduction of stability of other high-frequency aeroelastic modes. This tradeoff characteristic is similar to that observed for conventional wings and indicates that excessive wing stiffness cross-coupling is undesirable as a passive measure to control flutter.