Descent propulsion system

Descent propulsion system (DPS)
Country of origin	United States
Date	1964–1972
Designer	Gerard W. Elverum Jr.
Manufacturer	TRW
Application	Lunar descent stage propulsion
Predecessor	None
Successor	TR-201
Status	Retired
Liquid-fuel engine
Propellant	N; 2O; 4 / Aerozine 50
Mixture ratio	1.6
Cycle	Pressure-fed
Pumps	None
Configuration
Chamber	1
Nozzle ratio	47.5 (Apollo 14 and before); 53.6 (Apollo 15 and later);
Performance
Thrust, vacuum	10,500 lbf (47 kN) maximum, throttleable between 1,050 and 6,825 lbf (4.67–30.36 kN)
Throttle range	10%–60%, full thrust
Thrust-to-weight ratio	25.7 (weight on Earth)
Chamber pressure	110 psi (760 kPa) (100% thrust); 11 psi (76 kPa) (10% thrust);
Specific impulse, vacuum	311 s (3.05 km/s) (at full thrust); 285 s (2.79 km/s) (10% thrust);
Burn time	1030 seconds
Restarts	Designed for 2 restarts, tested up to four times on Apollo 9
Gimbal range	6° pitch and yaw
Dimensions
Length	85.0 in (2.16 m) (Apollo 14 and earlier); 100.0 in (2.54 m) (Apollo 15 and later);
Diameter	59.0 in (1.50 m) (Apollo 14 and earlier); 63.0 in (1.60 m) (Apollo 15 and later);
Dry mass	394 lb (179 kg)
Used in
	Lunar module as descent engine
References
References

The descent propulsion system (DPS - pronounced 'dips') or lunar module descent engine (LMDE), internal designation VTR-10, is a variable-throttle hypergolic rocket engine invented by Gerard W. Elverum Jr. and developed by Space Technology Laboratories (TRW) for use in the Apollo Lunar Module descent stage. It used Aerozine 50 fuel and dinitrogen tetroxide (N
₂O
₄) oxidizer. This engine used a pintle injector, which paved the way for other engines to use similar designs.