Inverse simulation for hypersonic vehicle analysis

This paper presents the development of an inverse simulation method for hypersonic vehicles and uses the method for design evaluation and trajectory analysis. Inverse simulation is a technique in which the control inputs, required to achieve a desired system output are computed through inversion of the system equations. Such analysis provides an insight into the capability of a vehicle to follow a given trajectory and allows the evaluation of vehicle controllability. In this work, the integration method of inverse simulation is used due to its increased exibility for vehicle models and trajectory inputs. Here the scramjet vehicle specific equations of motion, that incorporate look-up tables for vehicle aerodynamic properties are solved iteratively. In addtion the standard integration method is modified in order to mitigate non-convergence of the numerical method and to improve accuracy. The resulting inverse simulation routine was verified by evaluating a number of test trajectories described by sinusoidal fiight paths and a step increase in altitude. The results from these verification trajectories and the application of the inverse simulation algorithm to the linking trajectory used during the transition from the second stage (rocket powered) to third stage (scramjet powered) provide new insight into the controllability of the hypersonic Winged Cone Vehicle considered in this study.