A multi-mode propulsion system for potential application to hypersonic and aerospace planes. The system can employ various propulsion modes at various points in time, with the propulsion system employed at a given point in time being selected according to the velocity of the inlet airflow. In one embodiment, the propulsion system of the present invention has an ejector-augmented pulsed detonation rocket propulsion mode, a pulsed normal detonation wave engine mode, a steady oblique detonation wave engine mode, and a pure pulsed detonation rocket mode.