35 thoughts on “Virgin’s Engine Problems”

  1. IIRC before WWII Goddard wasted a lot of time with Gaseous Gasoline in his engine developments until he switched to liquid fuels and was successful. Later on he kept working with Gasoline while others changed to Kerosene which is a lot safer to handle on the pad.

    AFAIK there were designs for hybrid engines which used LOX instead of gaseous N2O so I do not think hybrids are out of the picture yet. But betting the farm on them is probably not a good idea. Not when liquid propellant engines are so easy to develop, cheap, and safe. Besides the supposed savings of having the solid fuel make no sense in a vehicle which will already require a pad to maintain like WK2. It makes sense to have solids on launch vehicles which you require to standby at a moment’s notice for prolonged periods like military rockets but it makes no sense in a reusable vehicle.

  2. I agree with the article in practically everything. The Ansari X-Prize was a bit of a bunk. It provided as much of a design that could viably do suborbital space travel as the Orteig Prize provided a viable commercial transatlantic flight plane. When I look at the prizes from that aviation era I always felt the most useful for actual technological development were the ones that were held in an annual basis as competitions between teams like the Schneider Trophy. The one time winner takes it all big bang scheme is seldom good in the long run.

    As for the liquid engines I felt much the same as the author. I mean who would choose a design that could not be easily refueled or throttled for a passenger transportation craft if he had the chance? Seems kinda bonkers in retrospect. I think this is one of those cases where Rutan’s love for the weird and wonderful caught up to him. Curiously enough in his other aircraft designs he usually used run-of-the-mill common as dirt engines.

    Still even liquid fuel expertise does not come cheap and I think outside of places like X-COR and SpaceX it just does not have the brainpower to even compute in developing an engine for something like this.

  3. Aren’t they already planning to switch to an all-liquid engine? And if it’s the nitrous oxide that blew up, then that’s a problem with nitrous oxide, not with hybrids.

    1. They’re working on liquid engines for LauncherOne but I’ve seen nothing official saying they were planning on using them for SS2.

      2. That’s exactly my question who does ever since Burt retired and they sold Scaled to Northrop Grumman?

        1. Burt never knew $hit about rockets anyway. One of my former bosses said it best – Burt Rutan designs the best crappy airplanes in the business.

          My understanding is that Scaled is a highly autonomous unit within NGC and can be selective about how they use the greater resources of NGC.

  5. Seems to me they got a little grandios…..if Space Ship One was safe enough and re-usable they had 2 pax seats…sholuld have been flying paying customers:

    “Rutan could have built another SpaceShipOne, but it is not in his nature to repeat himself. The ship’s tiny cabin – with two passenger seats directly behind the pilot – wasn’t ideal for space tourism. Rutan had something much grander in mind.

    That something was SpaceShipTwo, the world’s first suborbital SUV. With room for two pilots up front and six passengers in the back, the vehicle would have ample space for tourists to unbuckle themselves and float around the cabin. They would have a real space experience.”

    1. I agree. Should have gone to space with the spacecraft they had, not the one they wished they had.

    2. Space Ship One was not safe enough. That may have been the intention, but propulsion system reliability and aerodynamic stability turned out to be only marginally adequate for experimental use.

  7. That is indeed an outstanding article.

    While not exactly prescient, the timing was remarkable and it gave some good background information for today’s accident.

  8. Good article, but it has been my understanding that Rutan had very little to do with the actual design of SS2.
    His choice of the hybrid engine for Space Ship 1 was inspired, but continuing down that path isn’t working. I’ve also wondered about the low-wing design, and the in-flight video seems to show SS2 being less stable in the feather configuration. Back to the drawing boards, I hope they don’t give up, and I’m very sorry for the teams losses.

  9. Does anyone know at what altitude the pilot exited the vehicle? Was it greater than 135890 feet? I am assuming that after the engine explosion the pilot would have ridden the craft to apogee and then exited, but that’s just an educated guess with big error bars.

      1. Thanks. From the descriptions I’d seen so far, it wasn’t clear how far into the burn they were.

      2. And now I see Popular Mechanics is saying the anomaly was two minutes into the burn, and that the pilot who perished died on impact. So, there’s lots of misinformation out there.

        1. You’re right, there is a lot of misinformation out there. The engine was never designed to burn for two minutes. There are reports that the engine shut down after two seconds. Perhaps they attempted a restart some time later. At this point, who knows?

      3. Didn’t it launch from 71,000 ft. At 32 feet per sec per sec to get to 45000 would require
        40 seconds.
        Plus it would have had momentum, from the mothership going around 500 mph,
        so from launch point it should gain altitude, though mothership would gained more altitude
        after dropping it’s payload.
        If launched at 71000 it seems in next 10 seconds would have gained altitude if it was a rock,
        being a plane without power it would slow down quicker than a rock, but reach lower altitude
        than a rock. Plane could dive to be significantly lower then a rock would be- why would it? And
        if that desired, at 500 mph there limit to how quickly one change the vector of horizontal to upward direction, into say 45 degree dive.

        If assume it explode at near 71000 feet, and didn’t eject at that point, one assume to aviod
        spinning at huge gees, one should opt for 45,000 feet ejection.
        It seems it could immediately have began a spin resulting from the explosion, and at such thin air, the time of spinning, could made them blackout, and to aviod one bailout before this could happen. Or it was going to get any better, because not enough air to slow down the spin, so pilot had about 2 seconds of consciousness to make that call.

        1. WhiteKnightTwo can’t fly that high. It typically drops SpaceShipTwo between 45,000 and 50,000 feet altitude. On the previous powered flights, SpaceShipTwo needed a 20 second burn to reach 71,000 feet.

          1. Oh thanks, I misread a news article.

            So when Wiki says White Knight Two’s
            “Service ceiling: 70,000 ft (21,000 m) ”
            “Data from Virgin Galactic Presentation 2007”
            It is incorrect?
            Or do you mean they have not yet attempted it.

            I suppose that if White Knight Two were to fly to 70,000 feet
            there would a lot more safety concerns- everyone would
            have to be at least in a pressure suit.
            But I suppose as result of accident it may be that everyone will need
            them at 50,000 or even 45000 feet.

            I know that White Knight been flown to 50,000 ft, but suppose it
            possible with this new engine test flight they were launching at below 50,000 feet.

    3. They weren’t wearing pressure suits, just flight suits, helments, and a bailout oxygen mask. The explosion likely happened below 50,000 feet. Above about 40,000 feet, an oxygen mask alone isn’t sufficient – you need pressure on your body. When they lost cabin pressure (either as a result of the explosion or when the escape hatch was opened), there wouldn’t be much time before they’d pass out. There were no ejection seats, so getting out of their seats, opening the hatch, and bailing out would’ve been difficult. For one of them, it wasn’t possible.

  11. I would have never guessed that there was another space accident category called “loss of vehicle and part of the crew.” Has that ever happened before?

    2. Can a flight test that wasn’t supposed to ever leave the atmosphere be considered a space mission? There have been plenty of airplane crashes with loss of vehicle and part of crew.

      2. Good point. This was a high altitude aircraft accident. It was powered by a rocket engine, but it was not a spacecraft.

  12. Well, that could bring up some interesting perspectives. Is intending to go to space the defining criterion, or should it be that the vehicle is intended to be an all-up space craft? We usually count Apollo 1, even though it wasn’t conducting a launch into space when disaster struck. But would we have counted an accident with the captive carry and glide tests of the Space Shuttle Enterprise, which although designed to test the design of space vehicles, was itself just an atmospheric glider?

    Suppose the Space Shuttle had plowed into a fire truck on roll out? Would that count as a space accident or an airport accident? Working backwards from there, would a wheel blowout or landing gear failure be a space accident? Yet we feel a re-entry accident like Columbia is definitely a space accident, even though it occurred in the atmosphere, because Columbia had been in space. Yet Challenger never left the atmosphere but is still a space travel accident. But if Challenger had been lost while being flown cross-country on a 747 it would not have been.

    I think there are some nuances to all this.

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