SpaceX Kestrel

The SpaceX Kestrel was a liquid-fuelled rocket engine burning liquid oxygen and RP-1 kerosene, developed by SpaceX in the 2000s to power the upper stage of its small Falcon 1 launch vehicle. It was a pressure-fed design with no turbopump: the propellants were pushed into the chamber by tank pressure alone, which kept the engine simple and light, at about 52 kilograms. It used the same pintle injector architecture as the larger SpaceX Merlin engine. The chamber and throat were cooled by ablation and the nozzle, made from a high-strength niobium alloy, was cooled by radiation, while electro-mechanical actuators on the engine dome steered thrust in pitch and yaw and helium cold gas thrusters handled roll and coast-phase attitude. A TEA-TEB pyrophoric igniter gave it restart capability. Kestrel is no longer built, because the last Falcon 1 flight was in 2009; an enhanced Kestrel 2 was planned but dropped when the larger Falcon 9 replaced the Falcon 1.