Multidisciplinary optimization of airbreathing hypersonic vehicles

Airbreathing hypersonic aircraft and missiles are characterized by a high degree of interdependence between airframe and engine. For nonaxisymmetric vehicles the propulsion system exerts a major influence on vehicle lift and pitching moment; this in turn influences vehicle stability, control, and overall mission performance. Because of strong interactions between the airframe and engine, conceptual design of this class of vehicle requires a multidisciplinary design optimization (MDO) process that can simultaneously account for the impact of selected geometric variables on all vehicle subsystems. This paper describes the development and implementation of an MDO design system that combines propulsion and external aerodynamic forces, mass properties and internal volumetric modeling, and performs geometric optimization of a hypersonic cruise missile to maximize overall mission range. The result is a configuration with range 46% greater than the initial baseline. Such a dramatic performance increase is indicative not only of the power of optimization, but of the difficulty in configuring hypersonic vehicles to synergize the interaction of all vehicle components without MDO methods.