Ariane Economies of Scale

Ian Woollard wrote:

Michael Walsh wrote in message ...
Ian Woollard wrote:
Yes, you said that. It's not totally clear why you said that. If the
cost was much the same for example, then SSTO may be more desirable.

Nope.

So you are opposed to SSTO even if it turned out to cost the same?

Interesting...

An interesting misinterpretation of what I, perhaps not too clearly said.

I was referring to equal operational costs where I would expect that
the multi-stage system would have lower development costs than the
SSTO.

Then equal operating cost means you never get back the total cost
of your system.

The cost of developing the SSTO would, in my opinion, be higher
than that of a two stage vehicle.

Perhaps. However some of the early Atlas first stages demonstrate SSTO
mass fractions (about 5.5% dry mass); and they weren't even trying to
build an SSTO vehicle. Granted, the Atlas engines were only capable of
delivering an ISP of around 300 seconds; you would need around 330
seconds to make a single stage vehicle, but other engines are capable
of this level of performance, so it would seem not impossible to do
this.

Since the original Atlas was parallel staged there was a significant hunk
of booster engine that was dropped off about two minutes into the flight.
The Atlas is frequently put forth as an example of a non-reusable SSTO
vehicle, but it really was not.

Discussion of mass fractions of expendable SSTO vehicles is an
interesting exercise, but not one I would expect to see anyone
actually try to produce.

If you disagree with this, that is your opinion,
but not I believe a sound one.

This from a man who doesn't think that SSTO is worth it if it cost the
same?

Please try to carry out a reasonable discussion instead of distorting
my remarks.

Basically, a SSTO is a more difficult technical problem than the
TSTO systems.

Possibly; although it's easy to forget how complex a vehicle like the
Shuttle really is, and it's unclear whether an SSTO is more difficult
or easier than that overall, since whole structures disappear. It may
very well be somewhat easier/cheaper overall. (If done right; done
wrong it is impossible of course).

NASA claims that SSTO is beyond our current
technological level. However, this looks more like a way of
excusing management failures that resulted in them giving up on
the X-33 and X-34 rather than hitting technological barriers.

Definitely, although the X-33 atleast deserved to die from what I
could see.

I regard the process that resulted in the failed composite tanks as
primarily a management failure rather than a technical failure.
When the original project manager, David Urey, accurately points
to the composite, conformal tanks as the highest risk for the project
and the program just rolls on with the full-size flight tanks coming in
and failing in construction and ground test I call that a management
failure.

By the time the X-33 got to the point where NASA canceled it,
it deserved to die.

Mike Walsh