Effect of Control Surface-Fuselage Inertial Coupling on Hypersonic Vehicle Flight Dynamics

A simulation framework is developed for assessing the effect of control surface inertial loads on hypersonic vehicle response. The framework is based on a partitioned, time-marching approach in which the fuselage and control surface equations of motion are in-tegrated independently and forces/motion at the interface are exchanged between the two systems at pre-determined time intervals. This approach is advantageous in that it does not require direct coupling of the fuselage and control surface models, and therefore allows for the models to be of dissimilar form. Equations of motion for both the fuselage and control surface are presented and a formulation for coupling the two systems is outlined which includes iterations within each aeroelastic time step. The methodology is applied to a representative hypersonic vehicle elevator control surface model which includes aerother-moelastic effects and is attached to a single degree of freedom oscillator representing the fuselage. Results show that control surface inertial effects lead to a departure of the in-stantaneous control surface lift force by up to a factor of eight with respect to the static value. Investigation of the system response under a commanded change in control surface deflection angle shows that control surface inertia results in departure of the instantaneou