SUMMARYAir-breathing propulsion systems for high-speed space travel applications are studied. Ramjets and scramjets have been identified as potential candidates. The flow inlets of such systems are modelled with a simulation that can predict all complex inlet flow features, including shock due to forebody, multiple shock reflections, normal shock, shock-boundary layer interaction and associated separation for two-dimensional and axisymmetric inlets. Computed values are in good agreement with experimental data.