Re: Griffin Wants Inline SDLV and 5 Segment SRB/CEV

On Sun, 10 Jul 2005 21:39:58 -0400, in a place far, far away, "Murray
Anderson" <murraya@xxxxxxxxxxxx> made the phosphor on my monitor glow
in such a way as to indicate that:

>
>"Rand Simberg" <simberg.interglobal@xxxxxxxxx> wrote in message
>news:42e7eedd.169387997@xxxxxxxxxxxxxxxxxxxxxxxxxxx
>> On Sun, 10 Jul 2005 19:07:35 -0400, in a place far, far away, "Murray
>> Anderson" <murraya@xxxxxxxxxxxx> made the phosphor on my monitor glow
>> in such a way as to indicate that:
>>
>> >> >It wasn't necessary to have a fly-back booster - just recover the
>liquid
>> >> >boosters the way the SRB's are recovered.
>> >>
>> >> That would still have cost more than they had budget for (solids are
>> >> cheaper to develop than liquids, honest), and it's not at all clear
>> >> how refurbishable a liquid in that class would be after being dropped
>> >> in the ocean, Truax's limited experiments aside.
>> >
>> >They didn't know how refurbishable the solid would be either.
>>
>> They did, since they don't refurbish it--they rebuild it from the
>> recovered segments, with new grain.
>>
>It's the same with a liquid booster, except for the engine assembly - you
>just refill the tanks.

No, it's not that simple. The solids consist of segments, which can
be broken down and rebuilt. A liquid would have huge tanks that would
have to be inspected.

>The engine nozzle and gimballing system of the solid are supposedly
>recovered and reused, which would be like the engine assembly on the
>liquid - except for the turbopump system.
>There would be a difference if the turbopump system were harder to protect
>from seawater than the gimballing system on the solid.

As indeed it would.

>> >> Delta IV heavy doesn't have the payload they want, and getting it
>> >> (with man rating) probably will cost more than the development of the
>> >> Satay.
>> >>
>> >
>> >The payload was supposed to be 25 tons
>>
>> Emphasis on "was."
>>
>
>And the advantage of the stick is what? It doesn't exist so it can't be
>demonstrated not to meet the spec until it flies?

Again, go argue with them. I'm not defending the Satay.

>> >I
>> >> >accept that they can't do any better but don't quite see the
>connection
>> >> >between original design decisions and the flight rate. I'm not talking
>> >about
>> >> >the fantasies of 50 flights a year, but 10-12 a year would have been
>very
>> >> >helpful after the space station was started.
>> >>
>> >> Because they didn't design it for rapid turnaround, again due to
>> >> limited development budgets.
>> >
>> >That's a restatement of the problem in other words, together with a
>> >rationalization. What was it they wanted to do and didn't have the money
>> >for? A better thermal protection system would help, but that wasn't on
>> >offer, was it?
>>
>> With more money, yes. They could have, for example, used a titanium
>> structure underneath, instead of aluminum.
>>
>But the problem is the susceptibility to debris damage, not the insulating
>qualities of the tiles.

That's only part of the problem.

>Unless the tiles were all replaced by thermal
>blanket and it was less susceptible to damage. Anyway, was that the reason
>for using aluminum? I thought it was a combination of manufacturability,
>which is more schedule-related, and concern about interference with military
>programs.

It was for manufacturability, but that relates back, ultimately, to
cost.

>The leading edges would would still require carbon composite, but that
>susceptibility is more safety-related than maintenance related, so wouldn't
>impact schedule.

I've no idea what this means.

>> >Similarly, the external tank shouldn't shed foam to damage
>> >the tiles, but what tank design was turned down because it cost too much?
>>
>> The one that was incorporated into the Orbiter.
>
>That would imply a totally different design, possibly with dense
>propellant - and you may well be right about the cost here.

Yes. The point is that we had a very expensive "Shuttle"
operationally because we were unwilling to spend the money up front to
make it otherwise.
.

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