Design of an Air-Launched Tactical Missile for Three Different Propulsion Systems: ATR, Rocket and Turbojet
The objective of this paper 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 medium range tactical air-launched missile from an overall system point of view. A sizing method for missiles is developed, which together with flight performance calculations and engine performance data determines the final size and weight of the missile and its engine. The results suggest that an ATR engine is more favourable than a jet engine when the ratio between maximum (manoeuvre) thrust and minimum (cruise) thrust is large; for example for a mission including a cruise segment and a high load factor manoeuvre made at constant speed. For the missile range investigated in this paper no breakpoint in distance has been found beyond which the ATR engine becomes impractical. The rocket motor can produce a huge amount of thrust, thus giving it a very large maximum to minimum thrust ratio. However, it has a disadvantage in its low fuel efficiency and high combustion temperature, making it impracticable for missions requiring any longer duration. Altogether the choice of propulsion system has a large impact on maximum take-off weight, size and performance of the missile.