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.^[3] ^[4] ^[5] 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.

^ Bartlett, W.; Kirkland, Z. D.; Polifka, R. W.; Smithson, J. C.; Spencer, G. L. (7 February 1966). Apollo spacecraft liquid primary propulsion systems (PDF). Houston, TX: NASA, Lyndon B. Johnson Space Center. pp. 8–9. Archived (PDF) from the original on 23 August 2022. Retrieved 23 August 2022.
^ McCutcheon, Kimble D. (28 December 2021). "U.S. Manned Rocket Propulsion Evolution - Part 9.42: TRW Lunar Module Descent Engine (LMDE)". enginehistory.org. Retrieved 23 August 2022.
^ "REMEMBERING THE GIANTS - Apollo Rocket Propulsion Development - NASA" (PDF).
^ US Patent 3,205,656, Elverum Jr., Gerard W., "Variable thrust bipropellant rocket engine", issued 1963-02-25
^ US Patent 3,699,772, Elverum Jr., Gerard W., "Liquid propellant rocket engine coaxial injector", issued 1968-01-08