Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!pilchuck!seahcx!phred!petej
From: petej@phred.UUCP (Pete Jarvis)
Newsgroups: sci.space.shuttle
Subject: Re: How do they get it pointing up?
Message-ID: <2885@phred.UUCP>
Date: 11 Dec 89 14:47:49 GMT
References: <1989Nov29.094841.19907@jarvis.csri.toronto.edu> <648@sirius.ua.oz.au> <2871@phred.UUCP> <5519@hplabsb.HP.COM>
Reply-To: petej@phred.UUCP (Pete Jarvis)
Organization: <5519@hplabsb.HP.COM>o
Lines: 14

In article <5519@hplabsb.HP.COM> dsmith@hplabsb.UUCP (David Smith) writes:
>In article <2871@phred.UUCP> petej@phred.UUCP (Pete Jarvis) writes:
>>When the SSME ignite, causing the stack to sway forward and back again,
>>this is called "twang". The entire stack pivots. The SRB's do not flex.
>                                    ^^^^^ ^^^^^^      ^^^^^ ^^ ^^^ ^^^^
>Says who?
>
>			David R. Smith, HP Labs

David, if you've got something to add, why don't you? The orbiter stack
*does* pivot. You can easily see it. The SRB's move as a unit with the
orbiter during "twang".

Peter Jarvis, Physio-Control