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From: cage@fmeed1.UUCP (Russ Cage)
Newsgroups: sci.space,sci.space.shuttle
Subject: Re: Translunar/interplanetary shuttle?
Summary: Forget the idea already.
Message-ID: <8970@fmeed1.UUCP>
Date: 5 Dec 90 17:20:39 GMT
References: <3550@orbit.cts.com> <7089.275a4245@abo.fi>
Reply-To: russ@m-net.ann-arbor.mi.us (Russ Cage)
Followup-To: sci.space
Organization: Ford Motor Co., Electronics Div., Dearborn, MI
Lines: 31

In article <7089.275a4245@abo.fi> mlindroos@abo.fi writes:
>As for the problem with the main engines (we've been told here that they are
>not restartable), would it be possible to use the extra fuel for the OMS 
>engines instead...? (my guess is it won't be, anyway).

It would be easy to carry extra OMS fuel; it has been proposed
before, and I've seen depictions of orbiters with a rack of fuel
tanks taking up the back half of the cargo bay.

The problem is the low impulse of the OMS engines. To do a trans-lunar
injection burn, decelerate into lunar orbit, and burn again to return
to earth takes something like a million pounds of OMS fuel.  This is
about 20 Shuttle payloads worth.

Forget the idea of taking a Shuttle orbiter to the moon.  It's stupid.

Consider that the weight of the Shuttle's wings, tail, engines, landing
gear, thrust structure and thermal protection system is probably 130,000
of its 160,000 lbs weight.  Eliminate that and you've cut the fuel
requirements by 4/5.  Then dump the OMS engines and their fuel, and
carry a single RL-10 engine burning hydrogen and oxygen.  (These ARE
restartable, and have never failed to start or restart.)  This cuts
the required fuel drastically, and the cost of launching it.  What
you wind up with would be much smaller and cheaper than a Shuttle
orbiter for the same payload, and it could be built of off-the-shelf
engines and other parts.
-- 
Russ Cage	Ford Powertrain Engineering Development Department
Work:  itivax.iti.org!cfctech!fmeed1!cage   (CHATTY MAIL NOT ANSWERED HERE)
Home:  russ@m-net.ann-arbor.mi.us  (All non-business mail)
Member:  HASA, "S" division.