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.

With the introduction of Ariane 2 and Ariane 3, it became necessary to increase the performance of the HM-7 engine. This was achievd by raising the combustion chamber pressure from 30 to 35 bar and extending the nozzle, thereby raising the specific impulse. The burn time was also increased from 570 to 735 seconds. The upgraded engine was designated HM-7B and was qualified in 1983. The HM-7 engine versions have reliably powered the third stages of Ariane's 1 through 4 from 1979 to 2003.

The HM-7B engine, was also ntegrated from the third stage of Ariane 4 into the new Ariane 5 cryogenic upper stage - a tribute to the performance and flight proven reliability of an engine first developed 30 years earlier. The resulting upper stage was designated ESC-A (Etage Superieur Cryotechnique A) and increased the performance of Ariane 5 to 10 tonnes.

Use of HM-7B on Ariane 5 was a first step toward increasing the launcher's payload performance. A second step was the introduction of the new Vinci expander cycle engine to a new cryogenic upper stage, increasing the payload performance to 12 tonnes.

The Ottobrunn facility was responsible for the development and manufacture of the HM-7B thrust chamber comprising the regeneratively cooled combustion chamber, coaxial propellant mixing injectors, dump cooled nozzle etension, gimbal joint, and the LOX and LH2 propellant valves.

Important principles used in the HM-7 combustion chamber were adopted by NASA under licence and it was this technology that formed the basis of the US space shuttle main engines - the first reusable rocket engine in the world.