Encyclopedia Astronautica
MR-508


Redmond hydrazine monopropellant rocket engine. 230 mN. Communications satellite N-S stationkeeping, MMAS 7000. In Production. Isp=502s. First flight 1993.

First Flight: Telstar 4 (December 1993). qualified autumn 1991. Flown: 6 (28 produced) planned to end-1995. Dry Mass: 1338 gm. Length: 24.4 cm. Max Diameter: 9.27 cm. Mounting Method: bolted four places. Propellant: hydrazine at 0.068-0.077 gm/sec over Shell 405 catalyst and 1.8 kW. electric arc. Feed Method: GN2 or Ghe at 14.9-20.4 atm through Wright Components 9 W dual seat. solenoid valve. Thrust: 0.20-0.23 N. Isp: 502 sec vacuum. Time to Full Thrust: N/A. Expansion Ratio: 100:1. Nozzle Length: 0.879 cm. Nozzle Cooling Method: radiative. Combustion Chamber Pressure: 4.1-4.7 atm. Combustion Chamber Temperature: 800 Celsius. Combustion Chamber Cooling Method: radiative. Duty Cycle: 5 minutes minimum to 65 hr maximum. Itotal: 654 kNs.

Application: Communications satellite N-S stationkeeping, MMAS 7000..

Characteristics

Engine: 1.34 kg (2.95 lb). Chamber Pressure: 4.80 bar. Area Ratio: 100. Thrust to Weight Ratio: .01.

AKA: Low Power Hydrazine Arcjet.
Status: In Production.
Unfuelled mass: 1.34 kg (2.95 lb).
Height: 0.24 m (0.80 ft).
Diameter: 0.0927 m (0.3041 ft).
Thrust: 0.23 N (0.05 lbf).
Specific impulse: 502 s.
Burn time: 234,000 s.

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Associated Countries
See also
Associated Manufacturers and Agencies
  • Redmond American manufacturer of rocket engines. Redmond, USA. More...

Associated Propellants
  • Hydrazine Hydrazine (N2H4) found early use as a fuel, but it was quickly replaced by UDMH. It is still used as a monopropellant for satellite station-keeping motors. Hydrazine (N2H4) found early use as a fuel, but it was quickly replaced by UDMH. It is still used as a monopropellant for satellite station-keeping motors. More...

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