HM7-A

SEP, Ottobrunn LOx/LH2 rocket engine. Development begun 1973. Out of production. 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.