Path: utzoo!news-server.csri.toronto.edu!rutgers!usc!wuarchive!rex!samsung!umich!dgsi!gregc
From: gregc@cimage.com (Greg Cronau)
Newsgroups: sci.space.shuttle
Subject: Re: New Shuttle Computers
Message-ID: <1991Mar9.044834.27802@cimage.com>
Date: 9 Mar 91 04:48:34 GMT
References: <1991Mar4.202334.22118@casbah.acns.nwu.edu> <1991Mar5.013344.7971@umiami.ir.miami.edu> <1991Mar06.063034.12021@nowhere.uucp> <1991Mar7.010752.10632@agate.berkeley.edu>
Reply-To: gregc@dgsi.UUCP (Greg Cronau/10000)
Organization: Cimage Corp, Ann Arbor, MI
Lines: 28

In article <1991Mar7.010752.10632@agate.berkeley.edu> jwl@garnet.berkeley.edu (James Wilbur Lewis) writes:
>In article <1991Mar06.063034.12021@nowhere.uucp> sking@nowhere.uucp (Steven King) writes:
>>
>>   With the 230 lbs they saved they could put a couple hundred meg disk
>> array on each CPU and...  
>
>...watch their data get turned into a worthless pile of iron oxide if
>the spacecraft changes attitude while the drives are spinning!
>
>-- Jim Lewis

Actually, no. I have moved hard drives through several axies of rotation
while working on them to no ill effect. I would *not* recommend this be
done on a regular basis, however. Modern, small radius platers with light
weight winchester head technology should not be adversly affected. I doubt
that very much engineering work would be required to rate a drive for an
environment in which it would have to survive axis re-orientation while
operating. Most 3.5" harddrives that are used in laptops have to able to
handle this.
	HOWEVER, I would be much more worried about the effects of launch and
re-entry vibrations on the drive. THAT would be the killer.
	The bottom line is that harddrives are only useful in situations where
you will be *writing* alot of new data. The control program for the
shuttle is only *read* during flight, never written. A read only tape drive
can be made much more rugged than a hard drive.

gregc@cimage.com