Newsgroups: sci.space.shuttle
Path: utzoo!henry
From: henry@zoo.toronto.edu (Henry Spencer)
Subject: Re: SSME's
Message-ID: <1990Nov17.233940.26949@zoo.toronto.edu>
Organization: U of Toronto Zoology
References: <5687@crash.cts.com>
Date: Sat, 17 Nov 90 23:39:40 GMT

In article <5687@crash.cts.com> gandalf@pro-canaveral.cts.com (Ken Hollis) writes:
>>Don't read too much into this.  There has been no major design change, just
>>a bunch of small incremental improvements.
>
>The Main Engine Controller is a major upgrade for the engine, with completely
>new programming & components.

If I'm not mistaken, though, its external behavior is more or less identical.
Given that the MEC isn't a problem area of the engine, I think it fair to
class this as an incremental improvement.

>>The SSME is just too expensive to be a good expendable engine, though.
>
>Rocketdyne has been discussing the engines for the new generation ELV's
>(Expendable Launch Vehicles) and basically said that they would be a scaled
>down, less costly version of the SSME's.

It depends on which new-generation expendable you are talking about.  The
more sensible ALS people definitely would run miles to avoid using SSMEs
or any derivative thereof.  It also depends on who you are talking to.
Rocketdyne clearly has an interest in seeing that an SSME derivative --
built by Rocketdyne -- is used, as opposed to a new design done by
competitive procurement.  Considering how badly Rocketdyne's SSME has
failed to meet its promises, one might suspect that the next big engine
contract would go to someone else.  Rocketdyne is not an unbiased source.

I've seen a number of new-generation expendable proposals, and (ignoring
the explicit shuttle derivatives), Jarvis is the only one I can recall
that specified use of SSME derivatives.  Nobody who thinks he can afford
to (a) develop a new engine, (b) live without liquid hydrogen, or (c) live
with clustered RL-10s wants anything to do with the SSME.
-- 
"I don't *want* to be normal!"         | Henry Spencer at U of Toronto Zoology
"Not to worry."                        |  henry@zoo.toronto.edu   utzoo!henry