RocketMotorTwo is the name given by Scaled Composites to the rocket engine of their SpaceShipTwo spacecraft, to be used for sub-orbital spaceflight. The rocket motor is being designed and built by Sierra Nevada Corporation (SNC).[1]
Scaled Composites performed different subscale hot-firings between June 2005 and April 2009, before choosing a full-scale rocket motor system design[2].
During the early test phase of SpaceShipTwo's rocket system, on 26 July 2007, an explosion occurred during a fuel flow test at the Mojave Air & Space Port. The test included filling the oxidizer tank with 4,500 kg (10,000 pounds) of nitrous oxide followed by a 15 second cold flow injector test. Although the tests did not ignite the gas, three employees were killed and three injured, two critically and one seriously, from shrapnel wounds.[3]
As of June 2011, six hot-fire tests have been carried out on RocketMotorTwo.