Encyclopedia Astronautica
Merlin 1A

SpaceX Lox/Kerosene rocket engine. 378.040 kN. First stages. Hardware. Isp=300s. 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 However these plans were superseded by development of the Merlin 1C for the Falcon 9.

Application: First stages.


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

Status: Hardware.
Thrust: 378.04 kN (84,987 lbf).
Specific impulse: 300 s.
Specific impulse sea level: 270 s.
Burn time: 169 s.
First Launch: 2000-2004.

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Associated Countries
See also
Associated Manufacturers and Agencies
  • SpaceX American manufacturer of rockets, spacecraft, and rocket engines. SpaceX, USA. More...

Associated Propellants
  • Lox/Kerosene Liquid oxygen was the earliest, cheapest, safest, and eventually the preferred oxidiser for large space launchers. Its main drawback is that it is moderately cryogenic, and therefore not suitable for military uses where storage of the fuelled missile and quick launch are required. In January 1953 Rocketdyne commenced the REAP program to develop a number of improvements to the engines being developed for the Navaho and Atlas missiles. Among these was development of a special grade of kerosene suitable for rocket engines. Prior to that any number of rocket propellants derived from petroleum had been used. Goddard had begun with gasoline, and there were experimental engines powered by kerosene, diesel oil, paint thinner, or jet fuel kerosene JP-4 or JP-5. The wide variance in physical properties among fuels of the same class led to the identification of narrow-range petroleum fractions, embodied in 1954 in the standard US kerosene rocket fuel RP-1, covered by Military Specification MIL-R-25576. In Russia, similar specifications were developed for kerosene under the specifications T-1 and RG-1. The Russians also developed a compound of unknown formulation in the 1980's known as 'Sintin', or synthetic kerosene. More...

Associated Stages
  • Falcon 1e-1 Lox/Kerosene propellant rocket stage. Loaded/empty mass 42,168/2,712 kg. Thrust 615.50 kN. Vacuum specific impulse 304 seconds. More...
  • Falcon 1-1 Lox/Kerosene propellant rocket stage. Loaded/empty mass 22,993/1,505 kg. Thrust 369.00 kN. Vacuum specific impulse 300 seconds. More...

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