A Comparison of Methods for the Analysis of Wing-Tail Interaction Flutter

Abstract

Results of an analytical investigation of the aeroelastic stability of variable sweep aircraft, specifically with respect to wing-tail interaction flutter, are presented. Three aerodynamic representations are employed: 1) modified two-dimensional strip theory containing no wingtail aerodynamic interaction, 2) vortex lattice theory containing aerodynamic interaction of wing on tail only, and 3) subsonic kernel function theory containing a complete evaluation of wing-tail aerodynamic interaction. The capability of the interaction methods is established by an application to an experimental flutter model where wing-tail aerodynamic interaction is known to be of importance. The aerodynamic methods are then applied to a particular high performance variable sweep aircraft. The basic flutter mechanisms for this hypothetical aircraft are generated by wing-fuselage mechanical interaction and are predicted by wing aerodynamics alone. Component aerodynamics on wing and tail without interaction do not predict the mechanism. Aerodynamic interaction causes the reappearance of flutter at a velocity 30% lower than generated by the wing alone.