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
2O
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 range6° 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 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
2O
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