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From: oliver@vf.jsc.nasa.gov
Newsgroups: sci.space.shuttle
Subject: Re: Shuttle computers (Really, "Drop the landin' gear, Jed!")
Message-ID: <1991May3.150448.1@vf.jsc.nasa.gov>
Date: 3 May 91 21:04:48 GMT
References: <1991Apr26.111139.1@vf.jsc.nasa.gov> <1991Apr30.171707.27685@isc.rit.edu> <1991May1.162201.16502@zoo.toronto.edu> <1076@igor.Rational.COM>
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In article <1076@igor.Rational.COM>, wab@rutabaga.Rational.COM (Bill Baker) writes:

> I'm sure there is a perfectly reasonable, logical, and utterly
> necessary reason for this, but...
> 
> Why in the *hell* can they only *lower* the landing gear?
> Theoretically, I suppose, you only need to lower it in flight, but it
> still seems like bonebrain engineering to me.

There are two major reasons that I can think of.  First of all is why would you
want to raise the gear?  The Orbiter is a glider, it doesn't have the power to
go around on a missed approach, so there is not a flight requirement to raise
the landing gear.  Second, all the plumbing that it takes to raise the landing
gear has weight.  NASA tries to eliminate all weight which serves no useful
purpose, and on a space vehicle, equipment to raise the landing gear serves no
useful purpose.

Additionally, by not having the hydraulics system to raise the landing gear on
board the overall complexity of the hydraulics system is reduced.  This means
fewer things which have to be checked out during the vehicle turnaround.  Less
cost, less risk of something breaking, and just plain good engineering.
-- 

Pat Oliver -  	Lockheed Engineering and Sciences Company at NASA JSC
		2400 NASA Rd One, Houston, TX 77058 (713) 483-3323
		OLIVER@vf.jsc.nasa.gov