Flutter of Maneuvering Aircraft

Abstract

The objective of this paper is to investigate how the aeroelastic stability, particularly flutter, is affected by aircraft maneuvers. The authors’ investigation is based on a comprehensive mathematical model of aircraft, which is achieved by seamlessly integrating all the disciplines pertinent to flight of aircraft. The aircraft is treated as an unstrained, flexible multibody system subject to unsteady aerodynamics. The bodies are fuselage, wing, and horizontal and vertical stabilizers, whose structures are modeled as beams in bending and torsion. The equations of motion are derived using Lagrange’s equations in quasi-coordinates. The resulting equations are a set of nonlinear ordinary differential equations of relatively high order. The final model is used to determine flutter speeds of aircraft at steady level turn and steady climb at various altitudes. These maneuvers are especially chosen to keep the equations time invariant. The numerical results are given for a generic transport model (GTM). The stability of a GTM is affected by turn radius, climb angle, and altitude. The results for climbing flight can be extended to address stability of gliding flight.