Due to problems developing SpaceShipTwo’s engine, it appears that its first flight into space will not occur sooner than February 2014, and that commercial operations will likely not begin before the end of 2014.
The problem is that despite public claims to the contrary, the nitrous oxide-rubber hybrid has never been hot fired on the ground at full duration, sources indicate. And the engine is not powerful enough even when fully fired to get SpaceShipTwo into space with any actual payloads (i.e., six wealthy passengers). Even as Scaled Composites has pursued the flight test program and Virgin Galactic has issued optimistic flight predictions that commercial flights are only months away, the two companies have been secretly working on alternatives to the nitrous oxide-rubber engine they have been using to explore SpaceShipTwo’s flight envelope. Sources report that the development of alternative hybrid designs has been running into trouble. An engine that used nitrous oxide and nylon exploded on Scaled Composites test stand on May 17. The nozzle and rocket casing were thrown clear and the test stand was wrecked. The composite tank holding the nitrous oxide did not explode, but it was damaged to the point where it could not be reused.
This is very bad news. To develop a new engine at this late stage of development will be quite difficult. The spaceship itself was designed specifically with the first engine in mind. Any replacement will likely be different in power and design and require some changes to the ship.