Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!ingr!grimesga
From: grimesga@ingr.com (Greg Grimes)
Newsgroups: sci.space.shuttle
Subject: Re: How do they get it pointing up?
Summary: Thrust ramp up
Message-ID: <7851@ingr.com>
Date: 5 Dec 89 16:56:09 GMT
References: <1989Nov23.165606.27671@utzoo.uucp> <117.UUL1.3#5131@mvac23.UUCP> <1989Nov29.192322.6761@utzoo.uucp>
Organization: Intergraph Corp. Huntsville, Al
Lines: 19

In article <1989Nov29.192322.6761@utzoo.uucp>, henry@utzoo.uucp (Henry Spencer) writes:
> In article <117.UUL1.3#5131@mvac23.UUCP> mvac23!thomas@udel.edu writes:
> >I assume that one of the reasons that shuttle's engines start before the
> >solid boosters is to help counteract the tendency of the whole thing to
> >fall on the orbiter's back?
> 
> Yup.  The other reason is that you can abort a launch if problems occur
> in the orbiter's engines, but once the SRBs fire you are committed ...

I always thought it had to do the thrust ramp up time of the mains vs. the
SRBs.  Seems that the thrust curve for the SRBs is almost instantaneously
max while the mains take a few seconds to reach max.

--
-- 
Greg Grimes			|  These opinions are solely mine and
Intergraph Corp.		|  in no way reflect those of my employer.
Huntsville, Alabama		|  
uunet!ingr!fed_fe!greg		|		 :-)