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From: dsmith@hplabsb.HP.COM (David Smith)
Newsgroups: sci.space.shuttle
Subject: Re: center engine out
Keywords: Apollo
Message-ID: <5850@hplabsb.HP.COM>
Date: 19 Sep 90 20:49:16 GMT
References: <7285@eos.UUCP>
Reply-To: dsmith@hplabsb.UUCP (David Smith)
Distribution: sci.
Organization: Hewlett-Packard Labs, Palo Alto, CA
Lines: 24

In article <7285@eos.UUCP> brody@eos.UUCP (Adam R. Brody) writes:
>..middle engine of the S-1C first stage goes out while the surrounding four
>burn until completion.  The same thing occurs with the SII second stage at
>3:30.  Why is this?

To limit the peak acceleration loads.

>The book also mentioned that Apollo took 1.5 orbits around the Earth before
>TLI to gain momentum much like a discus thrower.  Can somebody explain this?
>Can it be like a gravity assist to another planet?

Not a gravity assist, nor momentum gain.  They wanted to go into a parking
orbit so they could check out vehicle operation in space before committing
to lunar transfer.  The orbit was inclined 28.5 degrees to the equator, and
if TLI occurred over Canaveral, the spacecraft would climb out toward the
opposite place in the sky 28.5 deg. south, where the Moon isn't.  Instead,
TLI took place in that part of the orbit which was opposite the planned
rendezvous point with the Moon.

-- 
"Some fear that Newtonian physics	| David R. Smith, HP Labs	
governs superpower relations:		| dsmith@hplabs.hp.com	
What goes up must come down."		| (415) 857-7898		
    Time Magazine, interviewing Gorbachev, June 4, 1990