HM7B

HM7B is the later cryogenic liquid-hydrogen/liquid-oxygen engine in the HM7 family, used on Ariane 4’s third stage and reused on Ariane 5 ECA’s ESC-A upper stage. Its firing duration depends on the installation: ESA’s Ariane 4 reference gives 780 seconds, whereas its Ariane 5 ECA profile gives nearly 940 seconds. The same references quote approximately 64.8 kN and 6.5 tonnes-force (about 63.7 kN) respectively. These source-specific stage figures describe the installed propulsion rather than a universal burn duration for every HM7B flight.