In the past three months Scaled Composites has conducted nine tests of SpaceShipTwo engines.

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The competition heats up: In the past three months Scaled Composites has conducted nine tests of SpaceShipTwo engines.

It also appears that one test was of an alternative engine to the one they have been planning to use. All told this suggests they are accelerating their effort to finish SpaceShipTwo.



  • Pzatchok

    Ok I have a question.

    Whats their big love affair with hybrid engines all about?

    Are the solid liquid engines just that much more powerful or are they just cheaper to operate?

    No serious company would spend cash like this unless their was a real serious reason to.

    And because, or I like them, is not a real serious answer.

    Just jack a liquid fueled engine into that frame and jettison it away once the fuel is gone. You can even slap a parachute on it to recover it.

    If its a weight issue then they are in some serious trouble. They will either have to upgrade their carrier craft or redesign the space ship to take the larger engine. More than likely both.

  • “Whats their big love affair with hybrid engines all about?”

    Hybrid engines use fuel that is safe or far less toxic, and therefore much easier and cheaper to handle. The goal is to replace fuels like hydrazine, which is very expensive to manage because of its deadly nature. The cost savings would be enormous.

    None of the companies that have been working for the government for decades has ever made any effort to do this. Only now, when private competition has been introduced into the aerospace industry, has an effort been made to save this money. If successful, it will reduce the cost of operations quite a lot, and make space more affordable.

  • joe

    Does any one know what the projected lifespan of one of these engines is?

  • If you are referring to hybrid engines, no one really knows. They are in development.

  • Joe

    No, sorry, I was referring to the conventional ones, are they single use or reusable?

  • Edward

    Joe, it depends upon whether it was designed for reuse. The pressures, temperatures, and stresses are tremendous, and if you want to use it multiple times, you need to design it that way.

    If it is thrown away after use, then it is easier to design, cheaper to make, and definitely easier to use. There is no concern over refurbishment, changed tempering of the materials, excessive wear over time, etc.

  • Pzatchok

    I can see the the benefits of a safer to handle engine but so far i have not seen any benefits in actual use.

    Unlike the solid boosters used on the shuttle these can be turned off and on in flight.

    But its looking like they are having trouble with the solid part falling apart and clogging the engine. Thus the kabooms.

    Even though they more than likely can throttle the engines up and down in power I can’t see it saving any solid fuel when they throttle it back.

    A similar thought to this has been tried for years in internal combustion engines.
    The idea of burning powdered coal instead of liquid fuel.
    Safer and cheaper.
    The solid fuels kept getting clogged or failed to ignite without some extra help. The problems just kept coming.

    Adding a small jet engine could give them the return to launch sight reliability and using a solid fuel booster instead of the hybrid could get them into space.
    Plus both would be much safer to operate and cheaper to implement.

  • Edward

    “Adding a small jet engine could give them the return to launch sight reliability…”

    Although that would likely add to safety, it would add weight, harming performance and the mission. There are always tradeoffs. I suspect that there will be many improvements over the coming years.

    Scaled Composites chose to try hybrids. XCore chose kerosene. Having the ability to try different solutions to a problem allows us to find better solutions and improve over time. Your suggestion may even be tried in the next generation of suborbital passenger rockets.

    Right now it is all an educational experience for engineers, and it is a steep learning curve.

    Bob Truax, where are you when we need you? (Yes, I know that he died, but he was ahead of his time.)

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