Aeroelastic Analysis of a Trimmed Generic Hypersonic Vehicle

The aeroelastic equations of motion governing a hypersonic vehicle in free flight are derived. The equations of motion for a translating and rotating flexible body using Lagrange’s equations in terms of quasi-coordinates are presented. These equations are simplified for the case of a vehicle with pitch and plunge rigid body degrees of freedom and small elastic displacements. The displacements are approximated by a truncated series of the unrestrained mode shapes, which are obtained using equivalent plate theory. Subsequently, the nonlinear equations of motion are linearized about the trimmed vehicle state in horizontal flight. Unsteady aerodynamic loads for the vehicle and the appropriate stability derivatives are calculated from piston theory. The methodology for calculating the aeroelastic stability boundaries is also described. Numerical results are currently being generated.