Newsgroups: sci.space.shuttle
Path: utzoo!henry
From: henry@zoo.toronto.edu (Henry Spencer)
Subject: Re: SSME Cost...
Message-ID: <1990Nov21.042644.19040@zoo.toronto.edu>
Organization: U of Toronto Zoology
References: <5759@crash.cts.com>
Date: Wed, 21 Nov 90 04:26:44 GMT

In article <5759@crash.cts.com> gandalf@pro-canaveral.cts.com (Ken Hollis) writes:
>Please be reminded that these are the first engines rated from sea-level all
>the way to the vacuum of space...

Nonsense.  The center engine on the Atlas, dating to the mid-1950s, burns all
the way from launch to orbit on a mission without an upper stage (e.g., the
Mercury orbital flights).

Actually, I'm afraid Ken hasn't thought this one through at all.  Even
first-stage booster engines are in near-total vacuum at burnout.  For
example, shuttle SRB burnout is at an altitude of over 40km, which is
in vacuum for all practical purposes (including rocket engine design).
There is enough air there to be detectable, but not enough to have major
effects on engine performance, since pressure and density are well under
1% of sea-level numbers.

>... They are also more
>complex because they COULD be made complex.  Computer systems & control
>systems that couldn't be made in Saturn days are now used on the SSME's.

And they have gained us virtually nothing to pay for all that extra
complexity.  Complexity for complexity's sake is a bug, not a feature.
Its only function is to keep lots of engineers and technicians employed,
which drives costs up and up and up.
-- 
"I don't *want* to be normal!"         | Henry Spencer at U of Toronto Zoology
"Not to worry."                        |  henry@zoo.toronto.edu   utzoo!henry
