Date:          Sat, 11 Dec 1999 18:39:37 -0600
From:          JIm Hannon 
To:            PSN-L Mailing List 
Subject:       Re: Mars Polar Lander "microprobe" accelerometers
Reply-to:      PSN-L Mailing List 

ted@.......... wrote:

> This must have been tough gear.  If my math is right, 400 mph is about 600
> ft/sec.  To decelerate from 600 ft/sec to 0 (assuming uniform deceleration)
> means that the avg speed during deceleration is 300 ft/sec.  At 300 ft/sec
> it takes about 14 msec to go 4 feet.  Therefore the deceleration must have
> been 300 / 0.014 = 21,400 ft/sec/sec or about 670 G's.  The science team
> was prepared to lose either probe if it hit a rocky surface (which would
> result in about 10,000 G deceleration I'd guess).  But they tested the
> units to thousands of G's on earth by firing them into the earth from
> airborne cannons.  (Why didn't I go to work for NASA?)
>
>
> Regards, Ted
>

I had a friend that used to design proximity fuses for cannon shells. He had
some interesting stories about what 10000 g
would due to common electronic parts. The  TO18 transistor can gets flattened
into a little disk.

--
Jim Hannon
http://soli.inav.net/~jmhannon/
42,11.90N,91,39.26W
WB0TXL



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