Ascent propulsion system
The ascent propulsion system (APS) or lunar module ascent engine (LMAE) is a fixed-thrust hypergolic rocket engine developed by Bell Aerosystems for use in the Apollo Lunar Module ascent stage. It used Aerozine 50 fuel, and N
2O
4 oxidizer. Rocketdyne provided the injector system, at the request of NASA, when Bell could not solve combustion instability problems.[2]
Country of origin
1964–72
Lunar Ascent Stage/Spacecraft propulsion
Bell 8247
Retired
1.6
None
1
46
3,500 pounds-force (16 kN)
16.7
120 psia
311 seconds (3.05 km/s)
465 seconds
Designed for 2 restarts
51 inches (130 cm)
31 inches (79 cm)
210 pounds (95 kg)
Development[edit]
During the spring of 1963, Grumman hired Bell to develop the lunar module ascent engine, on the assumption that Bell's experience in development of the Air Force Agena engine would be transferable to the lunar module requirements. Grumman placed heavy emphasis upon high reliability through simplicity of design, and the ascent engine emerged as the least complicated of the three main engines in the Apollo space vehicle, including the LM descent and CSM service propulsion system engines.
Embodying a pressure-fed fuel system using hypergolic (self-igniting) propellants, the ascent engine was fixed-thrust and nongimbaled, capable of lifting the ascent stage off the Moon or aborting a landing if necessary.[7]
The engine developed about 3,500 pounds-force (16 kN) of thrust, which produced a velocity of 2,000 meters per second from lunar launch, to LOR, and CM docking.[7][2] It weighed 180 pounds (82 kg), with a length of 47 inches (120 cm) and diameter of 34 inches (86 cm).[8]