HM4
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| Country of origin |  France |
|---|---|
| Designer | Société d'Etudes pour la Propulsion par Réaction |
| Application | Cryogenic Engine Testbed |
| Successor | HM7 |
| Status | Retired |
| Liquid-fuel engine | |
| Propellant | LOX / LH2 |
| Mixture ratio | 5:1 |
| Cycle | Gas-generator |
| Configuration | |
| Chamber | 4 |
| Performance | |
| Thrust | 40 kN (8,992 lbf) |
| Chamber pressure | 24kg/cm2 |
| Specific impulse, vacuum | 412 s (4.04 km/s) |
| Dimensions | |
| Dry mass | 198 kg (437 lb) |
| References | |
| Notes | Testbed engine, never flew |
The HM4 was a first non-American cryogenic rocket engine.[dubious – discuss][1] Developed in France between 1967 and 1969 it never flew into space, was used purely as a testbed for new technologies.[2] Technologies developed in HM4 become a base for HM7 engine used in Ariane.[3]