Ariane Economies of Scale

"Kim Keller" wrote in message . com...
"Hop David" wrote in message
...
Is mating vehicles difficult?

In the case of the shuttle, it is. Simply lifting the orbiter into position
for mating takes around 8 hours. Hard-mate generally takes around 18-24
hours, if all goes well. The entire process of completing mechanical and
electrical connections, plus checkout of the integrated stack takes about
five days of round-the-clock effort (been there, done that).

Interesting. Still the Shuttle takes about O(3 weeks) to recycle
doesn't it? Matter of interest where do the other two weeks go?

-Kim-

Rand Simberg wrote:

On Mon, 07 Jul 2003 00:32:06 GMT, in a place far, far away, Michael
Walsh made the phosphor on my monitor glow in
such a way as to indicate that:

The only virtue that a SSTO has over a TSTO (two stage to orbit) reusable
vehicle is the reduction in cost by developing and using only one vehicle
instead of two.

There are also theoretical operational cost reductions by not having
to mate the vehicles in turnaround, but at the current state of
technology it's not clear that the loss of performance margin of a
single stage doesn't wipe out this advantage.

OK, but that is just a clarification of what I posted.

Yes, because I (perhaps mistakenly) inferred that you were saying that
the main problem was development.

I didn't mean to imply that, but perhaps by putting development first made
it more important than the operational costs of using two vehicles.

In the long run, I would expect that the operational costs would be
more important, especially since the development of the SSTO should
have higher risk and probably a higher cost than the development of
one stage of a two stage vehicle. It might even be higher than the
cost of developing both stages.

The payoff of the SSTO would be from expected lower operational
costs.

Mike Walsh

"Ian Woollard" wrote in message
om...
Interesting. Still the Shuttle takes about O(3 weeks) to recycle
doesn't it?

I'm afraid I don't understand this statement. Could you clarify?

-Kim-

"Kim Keller" wrote in message . com...
"Ian Woollard" wrote in message
om...
Interesting. Still the Shuttle takes about O(3 weeks) to recycle
doesn't it?

I'm afraid I don't understand this statement. Could you clarify?

I assume that he's using "Big O" notation for the difficulty of a
task. It's a computer science term, and is generally used to
determine which algorithm is better on abitrarily large data sets.
It's not particularly useful for aerospace work since by definition it
completely ignores non-recurring costs.

I would assume he meant to say "roughly three weeks"

-jake

"Jake McGuire" wrote in message
om...
I assume that he's using "Big O" notation for the difficulty of a
task. It's a computer science term, and is generally used to
determine which algorithm is better on abitrarily large data sets.
It's not particularly useful for aerospace work since by definition it
completely ignores non-recurring costs.

I would assume he meant to say "roughly three weeks"

But I don't understand what effort he's referring to when he talks about
three weeks to recycle the shuttle. Recycle it after what? I could probably
give a semi-intelligent answer if he would elaborate.

-Kim-

h (Rand Simberg) wrote in message ...
On Sat, 12 Jul 2003 22:44:16 GMT, in a place far, far away, Michael
Walsh made the phosphor on my monitor glow in
such a way as to indicate that:

The payoff of the SSTO would be from expected lower operational
costs.

Yes, but because SSTO would have much less margin than a
(technology-equivalent) two-stage, lower operational costs may end up
being an illusion at current technology levels.

Not quite. By definition, SSTO has the same margin as a
technologically equivalent two-stager.

Ian Woollard wrote:

Not quite. By definition, SSTO has the same margin as a
technologically equivalent two-stager.

Not at all. For a given level of technology, the TSTO will
have more generous margins.

Paul

On 14 Jul 2003 20:48:55 -0700, in a place far, far away,
(Ian Woollard) made the phosphor on my monitor
glow in such a way as to indicate that:

The payoff of the SSTO would be from expected lower operational
costs.

Yes, but because SSTO would have much less margin than a
(technology-equivalent) two-stage, lower operational costs may end up
being an illusion at current technology levels.

Not quite. By definition, SSTO has the same margin as a
technologically equivalent two-stager.

??

Not at all, if you really mean "technologically-equivalent."

--
simberg.interglobal.org * 310 372-7963 (CA) 307 739-1296 (Jackson Hole)
interglobal space lines * 307 733-1715 (Fax) http://www.interglobal.org

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"Ian Woollard" wrote:
Not quite. By definition, SSTO has the same margin as a
technologically equivalent two-stager.

I like SSTOs but that's just nuts.

Ian Woollard wrote:

Not at all. For a given level of technology, the TSTO will
have more generous margins.

But increasing the margins is just using a lower level of technology.

Wrong.

Paul