NetNews Usenet Archive 1992 #31/NN_1992_31.iso/spool/sci/space/18082

Text File | 1992-12-22 | 1.8 KB | 39 lines

Newsgroups: sci.space
Path: sparky!uunet!spool.mu.edu!agate!rsoft!mindlink!a752
From: [e-mail] (Bruce Dunn)
Subject: Re: SSTO vs. 2 Stage
Organization: MIND LINK! - British Columbia, Canada
Date: Wed, 23 Dec 1992 02:57:44 GMT
Message-ID: <[e-mail]>
Sender: [e-mail] (Usenet)
Lines: 28

> David Smith writes:
>
> There's an advantage (I believe) of SSTO vs multi-stage systems that's
> getting left out here.  When launching a DC-1 all the engines are started
> and then throttled up.  This means that if an engine refuses to start,
> OR if there is a major fuel system problem such that none of the engines
> will start you can abort the launch on the pad.  With the two-stager
> enough engines have to start at separation time to assure that the DC-1
> can at least abort.

     Agreed.  Failure of second and third stage engines of conventional
launchers to ignite after staging has historically been a common cause of
launch failures.  However, I presume that the DC-1 will have the capability
of surviving at least 1 engine failure when at near maximum fuel load
(otherwise failure of any one out of multiple engines would cause a crash in
the period immediately following an SSTO takeoff).  If the DC-1 can survive
an engine shutdown after launch in SSTO mode, it seems to me that it should
be able to survive the failure of an engine to start after separation from a
booster.  Remember that since the DC-1 already has considerable upwards
velocity, it has time to burn off fuel, even with only some of the engines
operating, to get its weight less than its thrust.
        I grant that no amount of engine out capability will help a DC-1 if
it separates from the booster and none of the engines fire because of a fuel
problem.


--
Bruce Dunn    Vancouver, Canada   [e-mail]