Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!uwmcsd1!ig!agate!ucbvax!hplabs!hplabsb!dsmith
From: dsmith@hplabsb.UUCP (David Smith)
Newsgroups: sci.space.shuttle
Subject: Re: rockets with nozzles at the top
Message-ID: <4870@hplabsb.UUCP>
Date: 29 Aug 88 16:16:09 GMT
References: <1001@scicom.alphacdc.com> <44700006@pyr1.cs.ucl.ac.uk> <1988Aug28.000754.16300@utzoo.uucp>
Organization: Hewlett-Packard Laboratories
Lines: 19

> > ... Why is it not possible to use the OMS thrusters
> >to make a powered landing on the shuttle, if unpowered landings are so 
> >undesirable?  Extra fuel would be required...
> 
> I *think* they simply aren't powerful enough to be useful in a one-gee
> environment.  There may be other reasons; anybody know for sure?

Right.  I saw the OMS engines listed at combined 6000 pounds thrust.  Not
enough for a go-around, or (I would guess) even to make significant difference
in gliding range.  If the orbiter glides in at a 21 degree slope weighing
175,000 pounds, then it is getting 63,000 pounds of thrust from its weight.
If we get that same thrust from 6,000 pounds OMS + 57,000 pounds gravity,
we have a 19 degree glide slope.

-- 

			David Smith
			HP Labs
			dsmith@hplabs.hp.com