Newsgroups: sci.space
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: SSX: Space Ship Experimental (summary)
Message-ID: <1990Jan17.055635.27451@utzoo.uucp>
Organization: U of Toronto Zoology
References: <9001121009.AA01853@zit.cigy.> <11484@thorin.cs.unc.edu>
Date: Wed, 17 Jan 90 05:56:35 GMT

In article <11484@thorin.cs.unc.edu> beckerd@grover.cs.unc.edu (David Becker) writes:
>An area where this concept might need some serious new techonology would
>be rockets designed to operate for hours instead of minutes.
>Expendables run for minutes and chuck the engine.  The shuttle .. well
>excessive maintainance is what this SSX is supposed avoid.  When have
>have rocket engines been designed to operate with low maintainence for
>lots-o-launches? ...

At least one existing engine, the RL-10 used in Centaur, is cleared to
fire for an hour or more on a single mission, if anyone can find enough
fuel to keep it running that long.  Most regeneratively-cooled engines
have an almost unlimited life in principle.  The SSMEs are an unusually
bad case because they tried to push the technology very hard and it has
pushed back.  The high-time RL-10 has fired for four hours with relatively
modest maintenance.  Firing times of half an hour or more, spread over
a number of firings, with minimal maintenance, are not uncommon for
conservatively-designed engines.
-- 
1972: Saturn V #15 flight-ready|     Henry Spencer at U of Toronto Zoology
1990: birds nesting in engines | uunet!attcan!utzoo!henry henry@zoo.toronto.edu