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From: (Henry Spencer)
Subject: Re: X-Prize on TLC
Date: Thu, 20 Apr 2000 02:32:16 GMT

In article <>,
McLean1382 <> wrote:
>>Also significant is the military missile heritage of most existing
>>rockets:  the military wants maximum payload out of minimum missile, which
>>pushes strongly toward multiple stages, whereas making a space launcher
>>bigger (at design time) costs almost nothing.
>Vanguard, Saturn, Scout, Shuttle and Arianne V were all designed from scratch
>as space launchers. With multiple stages.

"Heritage" doesn't have to be hardware.  Every one of those, with the
marginal exception of the shuttle, was designed by *people* who grew up
designing missiles, and who approached the new task with mindsets already
built up.

For an example, you need look no further than the constant use of gross
liftoff mass as a crucial figure of merit for launchers.  Launcher cost
scales heavily with complexity, thinness of margins, and newness of
technology... and almost not at all with GLOM.  Obsessing over how *heavy*
the rocket is marks you as a missile designer.  The military cares a lot
about fitting missiles into existing silos, onto existing aircraft, within
existing treaties, etc.  Launcher designers rarely have such constraints.

In most of the cited cases, there were other constraints as well.  For
example, the shuttle design evolved haphazardly from an all-reusable
original which had two stages by decree... and even at the time, people
were heard to observe that when the orbiter started using a big drop tank,
the question of whether it really needed a booster stage should have been
reconsidered but wasn't.
"Be careful not to step                 |  Henry Spencer
in the Microsoft."  -- John Denker      |      (aka

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