Merlin 1A

SpaceX LOx/Kerosene rocket engine. First stages. Hardware. Completed development in early 2005. Pintle injector concept. Replaced by Merlin 1C. First flight 2006.

SpaceX Merlin engine was developed internally at SpaceX, but drew on pintle injector concepts developed at TRW for the lunar module descent stage engine. Propellant was fed via a single shaft, dual impeller turbopump operating on a gas generator cycle. The turbo-pump also provided the high pressure kerosene for the hydraulic actuators, which then recycled into the low pressure inlet. This eliminated the need for a separate hydraulic power system and eliminated thrust vector control failure through loss of hydraulic fluid. A third use of the turbo-pump was to provide roll control by actuating the turbine exhaust nozzle. SpaceX completed development in early 2005. The Merlin 1A, was a high pressure 342,650-newton at sea level thrust engine that was turbo-pump fed with a gas generator cycle. SpaceX began development on the Falcon V Merlin 1B upgrade engine (378,250 newtons at sea level) in 2005. The company expected to complete a Falcon V stage hold down firing with all M1B engines by the end of 2005. The next major engine development was Merlin 2, where SpaceX would aim for a significant increase in thrust and chamber pressure. Merlin 2 would serve as an exact scale version of the F-1 class (>6,675,000 newtons or 1.5 million pounds-force thrust) engine that SpaceX intended to start developing in a few years. However these plans were superseded by development of the Merlin 1C for the Falcon 9.

Thrust (sl): 317.700 kN (71,422 lbf). Engine: 760 kg (1,670 lb). Propellant Formulation: Lox/RP-1. Thrust to Weight Ratio: 94.