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From: Henry Spencer <>
Subject: RLV engines (was Re: X-33 Concepts: Lockheed, Mac Dac, Rockwell)
Date: Wed, 19 Jun 1996 13:03:12 GMT

In article <4q6am4$> (Andy Haber) writes:
>I think this is an area where critics can speak the loudest.  Today's 
>existing engines all leave something be be desired as true, good SSTO engines.
>This is mostly due to history.  Most engines (other than SSME's) were 
>designed for ELV's, not SSTO's.

Actually, this does not have a lot of bearing on their suitability for
RLVs.  Most ELV engines are, despite their application, reusable, because
they have to be developed and tested.  The F-1 was specified for 20 starts
and 2250s of life, the J-2 for 30 and 3750s.  Six F-1s ran over 5000s each
as part of the service-life tests.  DC-X's RL10s looked "pristine" after
20 starts; the RL10 is nominally rated for 10 starts and 4000s of firing.

>...In terms of using SSME's, sure those can used,
>although doing something to reduce the required level on maintenance on
>the existing engines is quite desirable...

Unfortunately, it probably can't go far enough.  Rocketdyne's own estimate
was that, with a *lot* of work, you could probably get SSME maintenance
costs down to $750k/engine/flight, which is unsatisfactory if you're aiming
for really large cost reductions.
If we feared danger, mankind would never           |       Henry Spencer
go to space.                  --Ellison S. Onizuka |

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