Six-Degree-of-Freedom Simulation of Hypersonic Vehicles

A three-dimensional, six-degree-of-freedom hypersonic vehicle model is being developed that more accurately characterizes vehicle dynamics for control studies. The main focus areas for this paper are the development of the rigid body dynamics equations of motion, the parametrization of the vehicle geometry, the formulation of the three-dimensional aerodynamic loads, and the adaptation of an existing 1D propulsion model. The aerodynamic loads are calculated by using or combining two-dimensional shock/expansion theory and the Taylor-Maccoll equations for conical flow. Comparisons with computational results show good agreement of resultant force and moment for the top and bottom vehicle surfaces and for most trials for the side surfaces. Using these models, the vehicle is trimmed for steady cruise conditions, and its flight dynamics are linearized about that state. This analysis provides information regarding the stability and controllability of a generic hypersonic vehicle in three-dimensional flight.