Due to problems developing SpaceShipTwo’s engine, it appears that its first flight into space will not occur sooner than February 2014

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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.



  • Pzatchok

    Never did like the idea of a composite fuel engine.

    Liquid and solid.

    Its just a combination that is waiting for a problem. The solid fuel shifts and clogs the nozzle for just a moment and BOOM.

  • Sayomara

    This sounds very bad

  • Tom Billings

    There is a small piece of good news here, however. Apparently the interrupts in the oxidizer line prevented the shockwave of the explosion from propagating back through the line to the tank. This is a real-world demo that such interrupts *do* work. This is important, because nitrous oxide, and especially the NOFBX blended monpropellants, are one of the major contenders in the “green propellants” intiatives, to replace hydrazine and nitrogen tetroxide propellants at equal or better performance.

    Successfully replacing hydrazines and their oxidizers with propellants that will not poison or dissolve humans they get spilled on will drop operating costs for capsules and lifting bodies alike, and steeply. Given today’s “safe at any cost” management culture in government, this should free private launch providers from steep compliance costs, once experience is gained with “green propellants”. NOFBX has a test series approved by NASA with a 100lb. thrust engine on an exterior module at ISS. I have not yet heard if anything has happened with that yet, or what the results are.

    At any rate, not blowing up a tank of an oxidizer that is itself not a bad monpropellant, and an even better one when blended with ethane, ethylene, and acetylene(which is apparently stabilized by being dissolved in the N2O), is a piece of good news for the intermediate future.

  • Robert Clark

    Thanks for that info. In point of fact studies have shown that ShipShipTwo if switched to liquid hydrogen fueled could on its own reach suborbital space without the need for a carrier aircraft. Moreover the engine needed is already existing in the engine for the cryogenic upper stage of the Ariane 5, though you may need two of them. This liquid fueled engine would also be reusable at least up to ten flights unlike the hybrid which needs to be replaced each flight.
    Not having to use the carrier aircraft WhiteKnightTwo would make both development cost and flight costs cheaper. And not having to spend money on developing a new engine would be also a big cut in the development cost. Being reusable the liquid fueled engine would probably be cheaper per use than the hybrid also.
    Keep in mind also that reusable liquid fueled engines were used from the very earliest times of rocket powered human flight in the X-15. This cut drastically the costs per flight.

    Bob Clark

  • Branson’s very public commitment to a “green” and “safe” propulsion system hasn’t helped. You’ve got to think at least *some* engineers at Scaled figured out early on that they could achieve equivalent levels of safety with a liquid bi-prop system, and get far better performance out of the vehicle. Not knowing the Isp or vehicle weights, I do wonder if an air-launched SS2 using something like Lynx’s engines could make 100km?

  • Pzatchok

    I have wondered about this for awhile.

    Whats their plan for achieving an actual orbit?
    Just going up and down is nice for a amusement park ride but what engines do they have in the works that will give them a real orbit?

    Reaching a geostationary orbit is OK but who else is out there? Who do they plan on docking with in order to stay longer than a few hours?

  • Edward


    Bigalow Aerospace is making space habitats, or space stations, that could be orbital destinations.


    Several countries have shown great interest in using these habitats and commercial manned spacecraft in or
    der to have their own space programs. These countries, many universities, and a whole bunch of companies have ideas for experiments to perform in these new space stations. There are so many ideas that the International Space Station cannot accommodate them all.

    The world’s governments have plenty of rules for using their rockets and their launch pads, and they have a limited number of pads. Commercial companies are not only making their own rockets and spacecraft, but they are researching ways to increase the throughput of each pad, and they are planning to build more pads.

    The future of commercial space is bright. All we really need is the way to get there without a lot of government interference or limitation.

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