Descent propulsion system

Descent propulsion system (DPS)
Country of originUnited States
Date1964–1972
DesignerGerard W. Elverum Jr.
ManufacturerTRW
ApplicationLunar descent stage propulsion
PredecessorNone
SuccessorTR-201
StatusRetired
Liquid-fuel engine
PropellantN
2
O
4
/ Aerozine 50
Mixture ratio1.6
CyclePressure-fed
PumpsNone
Configuration
Chamber1
Nozzle ratio
  • 47.5 (Apollo 14 and before)
  • 53.6 (Apollo 15 and later)
Performance
Thrust, vacuum10,500 lbf (47 kN) maximum, throttleable between 1,050 and 6,825 lbf (4.67–30.36 kN)
Throttle range10%–60%, full thrust
Thrust-to-weight ratio25.7 (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 time1030 seconds
RestartsDesigned for 2 restarts, tested up to four times on Apollo 9
Gimbal rangepitch 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 mass394 lb (179 kg)
Used in
Lunar module as descent engine
References
References[1][2]

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
2
O
4
) oxidizer. This engine used a pintle injector, which paved the way for other engines to use similar designs.

  1. ^ 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.
  2. ^ 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.
  3. ^ "REMEMBERING THE GIANTS - Apollo Rocket Propulsion Development - NASA" (PDF).
  4. ^ US Patent 3,205,656, Elverum Jr., Gerard W., "Variable thrust bipropellant rocket engine", issued 1963-02-25 
  5. ^ US Patent 3,699,772, Elverum Jr., Gerard W., "Liquid propellant rocket engine coaxial injector", issued 1968-01-08