A little from column a, a little from column b? It’s meant to be a spaceplane.
SpaceShipTwo, to my knowledge, has only ever flown as an aircraft. Highest alt 71k ft?
I think Tacitus said “The desire for safety stands against every great and noble enterprise.”
The people who knowingly risk their lives to advance our space industry have my respect and admiration, and the loss of any of them is grievous.
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Steps forward in technology can dangerous. For example how many brave souls perished so that your next airplane flight is safe. Thus this fellow perished so the spaceflight will be safe. Lessons are learned from this and the next time will better.
If the test pilots thought so, good for them. If the engineers and managers had thought so, it would be a betrayal of the test pilots, though.
(Ran out of <3.)
The test pilots have balls from aircraft-grade titanium.
But they still deserve an appropriate level of care in designing (AND TESTING!!!) the craft. The importance of testing is grossly underestimated, across industries.
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I heartily agree.
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I’d rather take a space elevator. Can we get one of those, already?
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yeah, and they build sea-going ships from steel now, are they nuts? that stuff doesn’t even swim!
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I was reading this prescient article a few days ago:
http://www.parabolicarc.com/2014/10/30/apollo-ansari-hobbling-effects-giant-leaps/
The gist of it was that the design history of SpaceShipTwo has followed the unusual path of designing the vehicle first, and then trying to build an engine to fit into it (rather than beginning with the engine and customising the vehicle around it). This non-ideal situation came about because the original designer was convinced that his hybrid gas/solid fuel mixture (nitrous oxide and rubber) could be made to work properly.
The failure of the hybrid to scale led to another problem. SpaceShipTwo had already been designed and built. The dimensions of the ship, the size of the passenger and crew cabin, the center of gravity…all those were already set. So, engineers now had to fit an engine within those parameters that could still get the vehicle into space.
It was not until May 2014 – after spending nearly a decade on the program, and a reported $150 million on engine development [and after the 2007 disaster] – Virgin Galactic announced it would be switching to a different type of hybrid engine, one powered by nitrous oxide and plastic. They are hoping for much better performance in flight.
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What could be done to prevent this? I don’t know. I think if you’re testing major modifications, it would help to be able to remote-fly the first few flights. ???
The developers have been cavalier about the lives of their employees so far; why start worrying about them now?
Consider the 2007 explosion that killed three engineers:
Explosions are not unusual in engine development. However, it is rare that anyone dies in them. Safety procedures call for the evacuation of personnel to a safe area before any tests begin. That was not done in this case; the dead and injured were part of a group of 11 people standing near the test stand.
Following the accident, Rutan and Scaled Composites claimed ignorance. “The body of knowledge about nitrous oxide (N2O) used as a rocket motor oxidizer did not indicate to us even the possibility of such an event,” Scaled said in a press release. The media and Scaled supporters have largely parroted this explanation.
The combination of hubris (“our technology is too innovative to fail!”), a reluctance of regulatory bodies to be seen trying to supress the poster child of private-enterprise inventiveness, and a desperate sense of urgency (from massive delays, cost-overruns and an eleventh-hour change of propellent technology) does not bode well for worker safety.
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Seems large amounts of N2O are a real bitch, and apparently it’s a mystery why : (
Interesting; it appears that the feathering was activated too early, and it wasn’t the engines that caused the crash.
It is decomposing to N2 and O2 and the reaction is exothermic. Anything exothermic has a degree of potential to go runaway. Add a spike of high temperature, e.g. by adiabatic compression, and you have a chance of things going haywire - this often happens with oxygen and traces of grease in valves (hence oxygen stuff tends to have left-handed threads to not accidentally mix the piping with non-oxygen, hydrocarbon-lubricated ones) and causes explosions. I saw even a description of a medical oxygen bottle explosion because of massive block of aluminium the valve was made from caught fire. This effect could have been the cause of the earlier explosion during the non-burn, flow-only test that killed three couple years ago.
The crash debris shown something that looked like a pressure tank, largely intact. My hypothesis is that there was no massive explosion of the oxidizer. The fuel grain itself could have developed a crack (and increased the burn surface and therefore burn rate).
I am waiting for more detailed reports. Hopefully the critical “witnesses” survived the crash intact enough to be able to “talk”…
That is actually a good news in the bad news. The engine is the heart of the ship and if something else failed, namely premature sequencing of attitude change that resulted in aerodynamic forces tearing the craft apart, it’s in the realm of not-that-new tech and easier to debug.
I feel a bit foolish for focusing all the time on a motor failure. To my defense, many others did too and given the amount of stored energy in the propellant, all itching to go exothermic, it was a too tempting red-hot-burning herring.
Seems very weird to me though. I’d have wanted the feathering to be at least as hard to activate when unsafe as thrust reversers post-Lauda air. There should be an awful lot of safeguards and inadvertent pilot commands shouldn’t be anywhere near close enough to trigger it.
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A lot of design requirements like this are obvious only in rear-view mirror. I thin it’s called 20/20 engineering hindsight.
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