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Post by Dave Homewood on Nov 1, 2014 9:15:34 GMT 12
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Post by kiwithrottlejockey on Nov 1, 2014 10:02:10 GMT 12
CLICK HERE to view a photograph gallery on the Los Angeles Times website.
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Post by Bruce on Nov 1, 2014 10:11:17 GMT 12
Very sad. Unfortunately this is very much the nature of space flight, as we have been reminded earlier this week. Despite all the years of R&D space flight is not "routine". flight profiles are extremely unusual, propulsion systems are complex and exotic and fuels are seriously volatile. I cant think of any space vehicle programme that has not had a major "Anomaly" or near disaster at some point in its development. Not only are the risks of failure high, the environment is extremely unforgiving.
Commercial space tourism may help fund projects, but i'm not convinced it is a wise idea. SpaceshipOne, as a prototype on which the whole venture is based, accumulated mere MINUTES of spaceflight time. Its like flying one circuit in a brand new airliner and clearing it for commercial operations. Own risk I know, but future passengers will always be essentially test crew / ballast paying their own way. Not sure how I feel about that concept.
I do hope that VG overcome this setback, it will not be in vain and it will help move technology forward.
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Post by ErrolC on Nov 1, 2014 10:45:22 GMT 12
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Post by nuuumannn on Nov 1, 2014 14:30:46 GMT 12
Very interesting piece on that site, Errol. Thanks for posting. The thing that strikes me is that this is a commercial venture and hybrid propulsion motors, such as that powering the SpaceShips are relatively untried technology with all the risks that come with the hope of introducing it into commercial operations, is it worth the extra R+D cost and risk factor? The advantages of hybrid motors are that they produce great amount of power for a small quantity of fuel over a short period of burn time; important for the type of operation that Virgin Galactic wants to run. There are existing alternatives however, that have been tried and tested, thus negating the extra expense and risk of new technology, especially considering the whole venture is new technology.
Despite Rutan's aversion to liquid propellant, there is plenty of reseach and types of fuel/oxidant mix for a light weight, powerful bi-propellant motor that meets the criteria for VG needs. The one that springs to mind is HTP as an oxidant. Now, the first thing everyone will think is "Me 163 Komet" and that is understandable, but the HTP argument is a bit like that of using hydrogen as a lifting gas for airships. Everyone knows it has a reputation for being unsafe, particularly in German hands, but the British used hydrogen rigid and non rigid airships as well and in the same quantities as the Germans, although theirs were largely non rigid blimps, and they only had one or two serious incidents with hydrogen, unlike the Germans, who had many, including the destruction of bases and ships, not to forget the very public loss of Hindenburg. The issue was one of quality control. This is where the British were superior to the Germans in their airship operations, which ensured far fewer incidents and loss of life as a result.
The same can be said about HTP. Post war, the British invested large amounts of effort into researching HTP rocket motors. At the Rocket Propulsion Establishment at Westcott a family of HTP motors was developed rather successfully, the most notable being the Gamma motor built by Armstrong Siddeley and fitted to the Black Knight sounding rocket and the Black Arrow satellite launcher. Both of these rockets were relatively successful and suffered no ill effects due to their engines or propellant. Part of the problem is that the US did not build any successful HTP motors, preferring to use LOx, but that is expensive to manufacture and difficult to store. Mind you, no one in either Britain or the US ever put a man atop an HTP rocket, so a big hurdle would be altering people's perspective of the stuff.
Essentially, no rockect propellant is perfectly safe and risk free; after all, you are essentially strapping yourself to a giant fire cracker; the whole thought of putting people into a rocket propelled vehicle is a crazy one and is full of risk, HTP or not, but it does have a stigma regardless of how safe it might be in a modern context. The cost of carrying out R+D into a synthetic alternative rules out commercial operations, but surely a decent liquid fuel motor using existing propellant can be developed that reduces costly research budgets, yet is safe enough for commercial operation. I guess the issue is money, as always, which seems to be the making of the choice of developing hybrid motors for commercial venture an odd one...
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Post by conman on Nov 4, 2014 6:41:44 GMT 12
Preliminary investigations suggest the mid-air breakup may have been caused by an uncommanded feather of the wings at supersonic speed and not due to the rocket motor at all, in a way that is more concerning, the pilot that survived seems to have been thrown from the aircraft while it was breaking up, a lucky escape.
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Post by kiwithrottlejockey on Nov 5, 2014 16:43:25 GMT 12
 (click on the picture) |
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Post by Dave Homewood on Nov 5, 2014 17:23:06 GMT 12
The most remarkable thing is the pilot who survived this parachuted from 50,000 feet with no oxygen and no pressure suit, and survived it with just a busted shoulder. One very lucky man!
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