Improved Analytical Model for Propelled and Unpropelled Hypersonic Vehicles

Hypersonic gliders are a new family of aerospace vehicles. They operate at quasi-orbital velocities with centrifugal acceleration balancing part of gravity. Although their aerodynamic lift-to-drag ratio is modest, the effective gravity resulting from a combination of the effects of gravity and of centrifugal acceleration allows for increased ranges. This paper presents an extension of traditional flight mechanics formulas over flat Earth to an oblate rotating Earth by including a relative gravity factor applicable to propelled and unpropelled flight. An analytical model is developed that includes this factor with formulations of flight time, cruising altitude, and range. Formulas for calculating gliding flight and accelerated and ascending cruise are developed. The model shows good agreement with high-fidelity simulation results. The simulation developed includes flight/orbital mechanics with an aerothermodynamic model of the scramjet and its multiple shocks air intake.