An integrated computational environment for multidisciplinary, physics-based simulation and analyses of airbreathing hypersonic flight vehicles will be developed. These vehicles are among the most promising alternatives for the next generation of Highly Reliable Reusable Launch Systems (HRRLS). The proposed work will enable development of models with varying fidelity, incorporating the coupled dynamic elements resulting from the tightly integrated airframe-engine configuration. These will include aero-propulsion and aero-elastic interactions as well as thermal loading. The effect of unsteady aerodynamics and nonlinear phenomena such as shock-shock interaction on vehicle performance will be evaluated. Simple and intuitive models for control design as well as high fidelity models for validation and simulation will be developed. The investigators' extensive experience with multidisciplinary software such as STARS and FLUENT will be an asset in this regard. Rather than creating completely new suit of software the approach proposed here is to develop new software when necessary but also produce codes which will enhance the present capabilities of existing software to handle coupled aero-propulsion as well as aeroelastic effects. The methods and products developed in this effort will significantly enhance the present capabilities for modeling, simulation, and control design, for airbreathing hypersonic flight vehicles.