Encyclopedia Astronautica
R-40A


Marquardt N2O4/MMH rocket engine. 3.870 kN. In Production. Isp=306s. Thruster developed for Shuttle Orbiter orbit control. The orbiter had 38 long scarf, short scarf, or no scarf configurations, depending on the location.

This thruster was developed for Shuttle Orbiter orbit control. The vehicle carries 38 long scarf, short scarf, or no scarf configurations. Depending on the location. Applications: spacecraft orbital maneuvering, perigee kick engine. First Flown: April 1981 on the Columbia. Dry Mass: 10.25 kg. Length: 55.4 cm short scarf version, 103.9 cm for the long scarf, and 88.9 cm for the satellite version. with 100:1 Expansion Ratio: Maximum. Diameter: 30.9 cm long scarf version, and 51.8 cm for the satellite version with 100:1 Expansion Ratio: . Mounting : fixed . Engine Cycle: pressure-fed. Oxidizer: nitrogen tetroxide at 0.838 kg/sec at 16.4 atm. Fuel: MMH at 0.52 kg/sec at 16.4 atm. Mixture Ratio(O/F): 1.6. Thrust: 3870 N (range 3114 - 5338 N). Isp: 281 sec (306 sec for 120 expansion ratio). Expansion Ratio: 20 (40 - 150 available for satellite version). Exit Diameter: 267 mm (328 - 635 mm for satellite version). Chamber Pressure: 10.5 atm. Combustion Chamber: single chamber of silicide-coated columbium (niobium) with welded-on orthogonal and scarfed nozzle extension in same material with internal film cooling. Exterior insulated for buried installation. Started by electrical signal to on/off solenoid valve. Multiple doublet injector with hypergolic ignition.. Burn Time: max 500 sec for single burn, qualified to 15,319 sec life. 289 Ns min impulse bit..

Engine: 10 kg (23 lb). Chamber Pressure: 10.50 bar. Area Ratio: 100. Thrust to Weight Ratio: 38.43.

Status: In Production.
Unfuelled mass: 10 kg (23 lb).
Height: 1.04 m (3.41 ft).
Diameter: 0.52 m (1.70 ft).
Thrust: 3.87 kN (870 lbf).
Specific impulse: 306 s.

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Associated Propellants
  • N2O4/MMH Nitrogen tetroxide became the storable liquid propellant of choice from the late 1950's. Monomethylhydrazine (CH3NHNH2) is a storable liquid fuel that found favour in the United States for use in orbital spacecraft engines. Its advantages in comparison to UDMH are higher density and slightly higher performance. More...

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