• windbourne

    awesome.
    Hopefully they start taking customers up this year.

  • Congrats to VG/SC/TSC! Great looking flight. I hope you are all totally successful in your endeavor.

  • Henry Vanderbilt

    Congrats to all involved on a successful powered flight, and best of luck for safe ops from here on.

    I haven’t been following this closely lately. What are they using for a fuel grain these days? And are they still injecting separately methane and helium?

    What they showed of the burn looked relatively smooth – shock diamond movements were relatively small, indicating relatively small pressure variations. Is there a vid of the full burn up somewhere?

  • Henry Vanderbilt

    Hopefully they start taking customers up when they’ve done enough uneventful test flights to be reasonably sure of having no major bugs still to eliminate.

    It’ll be interesting to see how soon the next powered test flight is. A high test tempo would be a good sign.

  • Kirk

    Is it flying inverted at 0:40, and is that a standard part of the flight profile?

  • Kenneth_Brown

    From what I have heard, the fuel is back to HTPB and that could mean that He isn’t needed anymore. The Nylon fuel grain needed the He and possibly the CH4 to modify the burn, but all of that tankage and plumbing deleted 2 seats in the back and added a bunch of mass.

    The big question is how smooth the burn is. Previously with the HTPB, after around 30 seconds the burn was so rough that it was difficult for the pilots to see properly and may have been violent enough eventually to cause injury.

    Going from memory, the nozzle looks different which might be why the diamonds changed.

  • Geoff T

    Certainly does appearing to be flying an inside loop there at the end of the powered run. Looking at footage from VSS Enterprises successful test flights and there didn’t seem to be a point where it flew inverted, even the feathering was deployed in a standard orientation.

    Wonder if there’s any significance to the manoeuvre here or just adding a bit more flair to proceedings?

  • Michael Halpern

    Probably to avoid looking at the Sun

  • Lee

    Amen.

  • Goosegoose

    At least they didn’t kill anyone this time. That’s a plus.

  • Goosegoose

    I seem to remember that Enterprise only burned for 20 seconds and got higher than Unity’s 30 second burn. That means the rocket motor got worse or the “spacecraft” got heavier. Or possibly both.

  • Kirk

    You sure? According to Wikipedia (which could be in error), VSS Enterprise had only three successful powered test flights, with the third burning for 20 seconds and reaching Mach 1.4 / 71,000ft (cf. Thursday’s flight of Mach 1.87 / 84,271 feet).

  • Douglas Messier

    Double Amen.

    Virgin Galactic executives have always said that safety was the north star of the organization and that they would fly when they were ready and when it was safe. It had little to do with the flight test program they were pursuing four years ago, but no matter. People bought it. And everyone kept their jobs.

    Hopefully, they actually mean it this time. Space is rather unforgiving; it has a nasty tendency to expose gaps between the illusions that people create for the benefit of the public and the realities of what they’re actually doing.

  • Francesco Barato

    Hi Doug,
    pleas look to this:
    https://www.researchgate.net/publication/289538639_Aerodynamic_Performance_Prediction_of_SpaceShipTwo
    particular chapter V
    The author now works at Blue Origin. The paper is from 2012, 2 years before the accident…

  • Douglas Messier

    They’re back to rubber nitrous oxide. There’s a backstory, of course.

    In December 2013, SNC figured out a way to stabilize the burn using helium. Lots of it. This cut into performance, and word was they could reach 50 miles with four passengers. SNC was rewarded for all its hard work at the beginning of the Memorial Day weekend by being dumped for a nylon-nitrous blend that Scaled had been developing on its own. Officials read about it in an Alan Boyle story on NBCNews.com.

    Supposedly the nylon engine had better performance, but the reality is was cheaper to pay Scaled for this than what SNC was charging. VG was short of money, so they went with the cheaper option.

    The nylon was a little harder to get started, so they used nitrous oxide at the start of the burn to get it going (avoids a hard start that would result in an explosion) and helium to stabilize the firing.

    The career of the nylon engine lasted 12 seconds in flight before something that Scaled and Virgin had overlooked (and the FAA had granted a waiver for) figuratively blew up in their faces: pilot error. Scaled hadn’t analyzed and mitigated for it, the FAA let it slide twice, and Virgin Galactic — whose north star was safety — did nothing. After the accident, Branson blamed the press, Mike Alsbury and Scaled — in that order.

    Although officials stressed how well the nylon engine burned for 12 of 38 seconds planned, they’re once again back to rubber nitrous that they’re producing inhouse.

  • Francesco Barato

    I think in the 4th paragraph you meant methane for the start…
    I will add also that the nylon motor was designed by Whittinghill aerospace for Scaled.

  • Goosegoose

    Not EVERYONE kept their jobs

  • Mr Snarky Answer

    They’re not illusions to informed public (informed by science and engineering that is). The safest thing to do is not fly at all. If anyone in the public thinks test flights of home built aircraft are particularly safe, let alone suborbital rocket planes, they are idiots.

  • Douglas Messier

    LOL. Plenty of people with more money than sense. Plenty of smart people with money who are not well informed on the risks of space travel.

    Regulations require informed consent but there are no limits on what companies can claim about the safety of their vehicles. So, how informed will people be?

  • Mr Snarky Answer

    As well informed as people are climbing up Everest knowing the history. I don’t lose any sleep over adults (regardless of net worth) taking on risky activities,this is a benefit of being quite libertarian in many ways. Adults are adults ignorance of reality (like the law) is no excuse.

    All one needs is access to Wikipedia and YouTube (and not just VG material). Look at the X-15 history, look at the history of other low flight rate vehicles. Look at the certification process for a commercial airliner by comparison (specially # of test flights).

    Look at the loss rate commercial airline per flight, private aviation, military tactical aircraft, and orbital space systems. Pretty easy to bracket suborbital on that continuum. All available in a few hours of reading to get a feel for what the deal is.

    Incidentally, while these flights are orders of magnitude more risky than commercial airline travel I don’t think they are overly dangerous compared to other risky activities, mountain climbing or acrobatic flying to name a few. I think you just single this one out because it’s in your backyard/wheelhouse.

    Losing a test pilot and aircraft by itself doesn’t portend a specific loss rate you are expecting. For example below is an engineer who died testing a system (due to bad testing methodology) for a rather benign transport system once in production. And no I am not directly comparing VG to an airport tram. I am comparing how flaws in testing methodology can be very dangerous but in the end the system is quite safe (relatively) once in production.

    http://www.nydailynews.com/archives/news/airtrain-driver-killed-testing-jfk-rail-link-article-1.512009

  • Douglas Messier

    Mt. Everest? There’s a history there to consult. Suborbital space tourism? Nothing. Zip. Nada.Rien. A giant goose egg.

    The rest of this involves a lot of assumptions and suppositions on your part not backed up by any data.

  • Mr Snarky Answer

    No, X-15 is very good analogue. Just because customers are onboard doesn’t change anything fundamental about the physics and probabilities involved (i.e. separation events, dry vs propellant mass fraction, redundancy in critical systems (or not).

  • patb2009

    the flight dynamics of the X-15 was very different.
    Now do most people understand there is some X percent chance they can die? I’d hope so.

    But I hope VG is making clear that there is a 1-10% chance of serious accident

  • Mr Snarky Answer

    Of course the flight dynamics are different, but the regime they are operating in is similar. Air drop is well understood from X-15, and other X planes / lifting bodies (even Pegasus).

    The powered flight portion of SS2 basically X-15 with the big engine at low throttle setting. How many flights do you think Crossfield could have done low throttle on the XLR-99 (no envelope expansion) before an accident and that was with 1950s engineering?

    As long as VG has properly qualified the engine (God help them if they haven’t done that by now) and properly vets the envelope with the feather out, the rest is pretty well beaten path historically. Given those two prerequisites they should be in better shape than X-15. Given the nature of the beast they are dealing with and the limited flights at best we are looking at 1:100 – 1:1000 vs 1:10000000 for commercial aviation until they can build up flight time. I think 1:10 is way pessimistic once they get through envelope expansion.