Design of air-lunched tactical missile concepts for three different propulsion systems: Air turbo rocket, rocket and turbojet

The aim of this study is to assess the feasibility of a solid propellant air turbo rocket (ATR), in comparison with a conventional turbojet engine or a solid rocket motor, as power source for a tactical air-launched missile from an overall system point of view. The ATR is a combined cycle engine, featuring a cycle where the turbine is isolated from the core engine flow entirely and powered by a separate gas generator. A sizing method for missiles is developed, which together with flight performance calculations determine the final size and weight of the missile and its engine. When comparing an ATR with a turbojet and rocket motor, respectively, the results suggest that the ATR powered missile gets the lowest weight when, during a mission, the ratio between maximum and minimum thrust is large and a long range or endurance is required. For short range missions a much simpler and more powerful solid rocket motor would probably be the best choice of propulsion, and for a long range mission, without rapid manoeuvres and dash requirements, a missile powered by a turbojet engine would have the lowest take-off weight.