These days, it seeems that everyone is talking about "order of
magnitude"
reductions in launch costs. The phrase rolls off the tounge quite
nicely
doesn't it? But I wonder if this is really feasible using today's
rocket
technology? Heck, I would be happy with a cost reduction of 3 or 4
times.
We could do a lot more low cost space missions if our cheapest orbital
launcher had a $3M price tag instead of $12M. But instead people are
enamored
with achieving this "order of magnitude" improvement. As Mr. Schnitt
points
out, this sounds a lot like the propaganda that was used to sell the
Space
Shuttle, and we all know how that turned out. I do believe that SSTO
programs
can be useful as technology development efforts, but not as the magic
solution
to all of our launch needs.
- Joshua Cohen
-New Space
Mr. Schnitt is quite right that minimum weight does not equate to to
minimum cost and this is also generally true not only for space launch
vehicles but also for transport and other aircraft. The common fallacy
that he describes seems to have come about due to as a result of long
periods
of experience with aircraft built of materials of nearly the same basic
cost and quite similar fabrication cost and powered by one type of
engine.
As the range of materials and- in the case of space launch vehicles-
engine
types- has expanded,the mmon fallacy leads the unwary further and
further
astray.But air craft design has not gone down the wrong path in recent
years. The obvious example of this fact is that major fractions of
aircraft
structure ( other than on V/TOL's, for which the cost- performance-
tradeoff
functions are substantially different from those of conventional
aircraft)
are not made with high strength/ high stiffness fiber composites as
they
would be if weight minimization were the driving design criterion.Thus,
if the rationale for minimum- weight design of launch vehicles is
supposed
to be found in aircraft experience, it no longer exists. Two other
recurrent
falacies that beset advancd launch vehicle design. as Mr Schnitt
indicates,
are that single- stage- to- orbit and maximum recoverability are
inherently
lower- cost solutions for space launch systems.The reasons for these
assumptions
have never been clear and the experience with the Space Shuttle belies
their validity in general.This is not hindsight on my part. I testified
to the Proxmire Committee at the start of the Shuttle program that
whatever
other virtues the Shuttle might have, it would never lead to lower
launch
costs. Al Flax
- Alexander H.Flax
- Consultant
With reference to the preceding comment by Joshua Cohen, I wish to
clarify
the term “order of magnitude” as it was used in defining the desired
reduction
in space launch costs. It was a slightly more definitive term than
“drastic”
or “major,” and that was the intent. No one knew how much of reduction
was possible; in fact, my limited design work has shown reductions of
less
and more than a factor of 10. Let’s take what we get when using the
more
rational design criteria for space hardware. It was gratifying to gain
the concurrence of Dr Flax. I am appreciative of the added arguments of
support he presented. It would be gratifying as well to hear from
individuals
in industry who are cognizant of airplane transport design. Would they
be kind enough to answer such questions as: Is the airplane life cycle
cost minimized on a strict basis, or, because this would result in the
airplane having too high a sales price for the market place, to what
extent
is the airplane minimum cost criteria modified? Is the value of a pound
of weight used in the airplane design? Since this value is location
sensitive,
is a computer program used to achieve a balanced design?
- Arthur Schnitt
- Consultant