Encyclopedia Astronautica
HM7-A


SEP, Ottobrunn lox/lh2 rocket engine. 61.7 kN. Development begun 1973. Out of production. Isp=443s. Used on Ariane 1 launch vehicle. First flight 1979.

The HM-7 rocket engine featured Ottobrunn's unique regenerative cooling technology whereby hydrogen propellant was efficiently used to cool the combustion chamber before being injected for combustion. In 1973, the Ottobrunn team started development of the HM-7 thrust chamber for Ariane's upper stage rocket engine. Six years later, the HM-7 engine was successfully qualified with the first launch of Ariane 1 in December 1979.

Thrust (sl): 42.900 kN (9,644 lbf). Thrust (sl): 4,372 kgf. Engine: 149 kg (328 lb). Chamber Pressure: 30.00 bar. Area Ratio: 62.5. Thrust to Weight Ratio: 42.2080536912752. Oxidizer to Fuel Ratio: 5.15. Coefficient of Thrust vacuum: 1.82800988360581.

Status: Out of production.
Unfuelled mass: 149 kg (328 lb).
Height: 1.71 m (5.61 ft).
Diameter: 0.93 m (3.05 ft).
Thrust: 61.70 kN (13,871 lbf).
Specific impulse: 443 s.
Specific impulse sea level: 308 s.
Burn time: 563 s.
Number: 11 .

More... - Chronology...


Associated Countries
See also
Associated Launch Vehicles
  • Ariane 1 French orbital launch vehicle. First version of the Ariane launch vehicle. More...

Associated Manufacturers and Agencies
Associated Propellants
  • Lox/LH2 Liquid oxygen was the earliest, cheapest, safest, and eventually the preferred oxidiser for large space launchers. Its main drawback is that it is moderately cryogenic, and therefore not suitable for military uses where storage of the fuelled missile and quick launch are required. Liquid hydrogen was identified by all the leading rocket visionaries as the theoretically ideal rocket fuel. It had big drawbacks, however - it was highly cryogenic, and it had a very low density, making for large tanks. The United States mastered hydrogen technology for the highly classified Lockheed CL-400 Suntan reconnaissance aircraft in the mid-1950's. The technology was transferred to the Centaur rocket stage program, and by the mid-1960's the United States was flying the Centaur and Saturn upper stages using the fuel. It was adopted for the core of the space shuttle, and Centaur stages still fly today. More...

Bibliography
  • Kudryavtseva, V M, ed., Zhidkostnikh Raketnikh Dvigatley, Visshaya Shkola, Moscow, 1993.

Associated Stages
  • Ariane H8 Lox/LH2 propellant rocket stage. Loaded/empty mass 9,687/1,457 kg. Thrust 61.67 kN. Vacuum specific impulse 443 seconds. High energy upper stage for Ariane booster series. More...

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