[AR] Re: SpaceShipTwo crashes shortly after Mojave test flight
- From: Anthony Cesaroni <acesaroni@xxxxxxxxxxx>
- To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
- Date: Sat, 1 Nov 2014 22:37:25 -0400
Here is the NTSB B-Roll from today. Notice the pressure vessel at 2:40 to 3:00
in the video.
http://www.youtube.com/watch?v=cZnQcMpzunM
Here is the vertical test firing from last May.
Notice the similar shape and also the bracket holding the cylinder.
Looks very similar to the one in the NTSB video.
https://www.youtube.com/watch?v=c37I8JS2vmc
I'll get back to you and your question tomorrow Peter.
Anthony
Sent from my iPhone
> On Nov 1, 2014, at 5:01 PM, Peter Fairbrother <zenadsl6186@xxxxxxxxx> wrote:
>
>> On 01/11/14 18:55, Rick Newlands wrote:
>> From your descriptions, and the fact that the tank is more or less
>> intact, definitely sounds like an engine failure. If the tank had gone
>> up there's no way one of the pilots would have been alive to parachute out.
>>
>> I'd reckon that part of the fuel grain broke off and blocked the nozzle.
>> The chamber pressure then rose and one of the engine bulkheads blew off,
>> sending a huge shock through the airframe that broke it apart.
>>
>> They've recently switched to a nylon fuel grain, which is a good thing
>> in general (nice, clean, almost transparent exhaust) but it might be
>> that they hadn't ground-tested the new grain sufficiently. It's cold
>> 50,000 feet above the desert, a fuel fin might have become brittle and
>> snapped-off.
>
> That's what I thought too. Or maybe just some energetic chugging. And maybe
> the acceleration helped (aiui the new grain/engine had been tested quite a
> bit on the ground, but hadn't been tested in flight before).
>
> Isn't it long past the time VG scrapped the nitrous hybrid engine, and went
> to a solid, or better a LOX/kero biprop?
>
>
>
>
> Scaled won the Ansari X Prize contest because Bert Rutan is very good at
> making lightweight aircraft, and the reusability rules meant that a hybrid
> would be the cheapest and fastest engine to be developed. Plus the angel
> helped.
>
> Scaled did not choose a nitrous hybrid because they thought it would be the
> safest or most reliable engine; and after the previous nitrous fatalities I
> had hoped they would learn their lesson and stop using nitrous hybrids.
>
> AIUI, they didn't choose a solid because the rules wouldn't allow it for the
> contest; and they didn't choose a liquid biprop because it would take longer
> to develop for the contest.
>
>
>
> But the contest is now over. Those reasons for choosing a nitrous hybrid are
> now extinct. There is *no way* a nitrous hybrid is the best engine choice for
> spaceship two.
>
>
>
> Nitrous hybrids - well, I have never thought they were suitable for human
> propulsion.
>
> First, they chug. Does anyone know exactly how that works? Thought not.
>
> Second, hybrids don't scale well. That is well-known, and has been known for
> a long time.
>
> And third, nitrous is a bipolar bitch - one minute she is pliant, the next
> she cuts off your balls. Assuming we are correct, nitrous hybrids have now
> bitten Scaled/successors twice.
>
>
> Q particularly for Anthony Cesaroni, if he would like to answer, but also
> generally - how much would it have cost to develop a human-suitable solid for
> SS2, and how much per shot?
>
> Q for the list - how hard/expensive/ would it be to develop a human-suitable
> LOX/fuel biprop engine?
>
> There is a saying in rocketry, don't develop a new engine for your project -
> what does that say about the advisability of developing a whole new class of
> engine? Especially for human passengers?
>
>
>
> Kudos to the brave pilots, and my sympathy to their families.
>
> But bad cess to the overall project design engineers, if such exist.
>
>
> -- Peter Fairbrother
>
>
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