Entering service with the first Ariane launch in 1979, the HM7 cryogenic engine (later the HM7B) powered the third stage of all Ariane 1 to Ariane 4 launchers. On the heavy-lift Ariane 5 ECA, the HM7B powers the cryogenic upper stage.
Snecma’s HM7B is a cryogenic rocket engine, fueled by liquid oxygen and liquid hydrogen. It has undergone continuous improvements over the years to increase thrust, specific impulse, burn time and reliability.
The HM7B is a particularly reliable engine, proven in service. Nearly 200 have been produced to date.
Delivering 14,300 pounds of thrust (64.8 kN), it propels Ariane 5’s upper stage for nearly 15 minutes, imparting to the satellite(s) the speed needed for injection into geostationary transfer orbit.