| Country of origin | United States |
|---|---|
| Designer | Sierra Nevada Corporation |
| Manufacturer | Virgin Galactic |
| Predecessor | RocketMotorOne |
| Status | Active |
| Hybrid engine | |
| Propellant | Nitrous oxide / Hydroxyl-terminated polybutadiene |
| Performance | |
| Thrust | 310kN |
| Specific impulse | 250 s (2.5 km/s) |
| Burn time | 60 seconds |
| Used in | |
| SpaceShipTwo | |
RocketMotorTwo (RM2)[1] is a family of hybrid rocket engines developed for the Scaled Composites SpaceShipTwo suborbital spaceplane.
The first-generation engine was developed by Sierra Nevada Corporation (SNC),[2] from the late 2000s to May 2014. It was first ignited in flight during a SpaceShipTwo test launch in April 2013.[3][4] This engine design was subsequently flown in only two additional flight tests during 2013 and January 2014.[5] SNC was a subcontractor to Scaled Composites through May 2014 when their involvement in the program ended after Virgin Galactic elected to replace SNC's version of RocketMotorTwo powered by HTPB rubber fuel, with its own internally developed hybrid motor for SpaceShipTwo.[5]
The second-generation RocketMotorTwo engine is a variant of the earlier SNC basic design. It experimented with using a polyamide plastic fuel and nitrous oxide oxidizer in 2014,[6] but switched back to using its original hydroxyl-terminated polybutadiene (HTPB) fuel and liquid nitrous oxide oxidizer in 2015.[7] The second-generation engine is now made in-house by Virgin Galactic rather than by SNC.
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