RocketMotorTwo (RM2)[1] is a family of hybrid rocket engines developed for the Scaled Composites SpaceShipTwo suborbital spaceplane.
The company also developed the rocket engine for the first private spacecraft to reach space, SpaceShipOne, which won the Ansari X-Prize in 2004.
In July 2012, Virgin Galactic, the owner of VSS Enterprise – the first SpaceShipTwo spaceplane built – announced that RocketMotorTwo was fully qualified for powered flight, and that the ground test program was substantially complete.
The test was a 16-second burn as planned, and was ignited at an altitude of 47,000 feet (14,000 m), shortly after Enterprise was released from its WhiteKnightTwo carrier aircraft and the pilots cross-checked data and verified stable control.
SNC stated after the test that "The rocket motor ignition went as planned, with the expected burn duration, [and] good engine performance.
[22] Rather than use rubber-based HTPB in the solid portion of the hybrid rocket motor—which had experienced serious engine stability issues on firings longer than approximately 20 seconds with the first-generation engine—the Virgin Galactic-developed SS2 hybrid rocket engine would now use thermoplastic polyamide (i.e., nylon) as the solid fuel component of the propellant.
The plastic fuel was projected to have better performance (by several unspecified measures) and was expected to allow SpaceShipTwo to make flights to a higher altitude.
[26] While the US government National Transportation Safety Board (NTSB), which is leading the investigation, has released only "statements of fact", space journalist Irene Klotz has stated more explicitly that "[i]t wasn’t SpaceShipTwo’s hybrid rocket motor – which was flying ... with a new type of fuel – that caused the fatal crash.
[29] The HTPB hybrid rocket motor and its oxidizer valve system were produced in SNC's manufacturing facility in Poway, California in conjunction with Scaled Composites.
In 2013, the Poway facility was reported to be "currently producing motors for both SpaceShipTwo and SNC’s own Dream Chaser orbital crew vehicle".