An analytical model of dynamics for generic airbreathing hypersonic vehicles

An analytical model of dynamics for generic airbreathing hypersonic flight vehicles is developed. The model captures engine factor, elastic deformation, a spherical rotating Earth mode, and aerodynamics. Unlike conventional vehicles, the mutual interactions between the propulsion system and the fuselage have important influence on the dynamics characteristics of vehicle and the performance of the SCRAMjet. Furthermore, for the fuselage of the airbreathing hypersonic vehicle is flexible structure, elastic deformation of fuselage is important to the performance of the propulsion system. It is not suitable for these factors to be handled in conventional way. The equations of motion are derived using Hamiltonian equation. The result equations include the rigid-body motion, which includes the translational and rotational velocities of axes system, and elastic motion based on the elastic mean axes system. According to the analysis of the result equations and simulation, the first bending mode of the fuselage is important as its deflection affects the amount of airflow entering the engine, and in most cases, lead to the unstable short-period mode. It was found that Coriolis force can reach to 2% of the vehicle weight for a cruise vehicle in atmosphere.