Rocket-powered Aircraft
Rocket propulsion offers very high thrust for light weight and has no height limit, but suffers from high fuel consumption and the need to carry oxidant as well as propellant.
Rocket-powered aircraft have been experimented with, and during the Second World War the Messerschmitt Komet fighter was developed and used operationally. Since then they have been restricted to specialised niches, such as the Bell X-1 which broke the sound barrier or the North American X-15 which was capable of flying at extremely high altitudes at the border with space as it was not dependent on atmospheric oxygen.
Rockets have more often been used as a supplement to the main powerplant, typically in the case of rocket-assisted take off to give more power for a heavily loaded aircraft or reduce the takeoff run. In a number of designs such as the prototype "mixed-power" Saunders-Roe SR.53 interceptor a rocket was used to provide high-speed climb and speed to reach the target while a smaller turbojet provided a slower and more economical return to base.
Read more about this topic: Powered Flight, Methods of Propulsion, Jet Propulsion