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The Lucas Torpedo

To: british-cars@autox.team.net
Subject: The Lucas Torpedo
From: megatest!bldg2fs1!sfisher@uu2.psi.com (Scott Fisher)
Date: Fri, 6 Aug 93 14:04:14 PDT
Six or seven years ago, I worked with a fellow with the very British
name of Ken Appleby.  He had a Spitfire, I had my '74 B, and we used 
to motor out to Pickwick's Pub and throw darts after work on occasion.

Ken used to work for Lucas in the UK, specifically for a division
of Lucas that did military electronics.  My favorite of his stories
was about the time he had been working on a computer-controlled
torpedo.  It used magnetic core memory to store the programs, which 
had the advantage of being very non-volatile as well as not susceptible
to EMP discharge.

So Ken got to ride on the boat for the first test of the torpedo that
used the computer with his program in it.  Somewhere out in the North
Sea, on an R. N. cutter, Ken and his crew launched the first ever run
of this new weapon, and Ken learned a new respect for debugging...

The program was supposed to make the torpedo shoot off the boat, dive
to a depth at which it couldn't be easily detected, then circle
toward the target, climb to striking depth, and hit the target.  There
were on-board sensors to detect sea level, and the torpedo was supposed
to travel at a preset distance below sea level, with constant feedback
keeping it on track.

Somehow, somewhere, Ken had multiplied one of the 3D coordinates by 
a negative number, and this error soon propagated through the 
transformation matrix (the mathematical construct that models 3D
space), with predictable results.

Within instants of hitting the water, the torpedo -- instead of
sinking out of visible range -- blasted up and out from the water in
a great silver fountain, then continued skipping across the surface of
the blue like some sort of deranged wingless flying fish.  Worse yet,
instead of circling toward the target, it circled all right, but began
to return to the ship that launched it.  Fortunately it was not armed,
but they still detonated the self-destruct on it rather than let it
slice through their ship at 50 knots or whatever rate it travelled.
Because of the non-volatile core memory, Ken was able to debug the
program from what the Royal Navy frogmen could recover from it, and
he fixed the problem for Rev 2.0.

But I must admit that the image of the torpedo, splashing happily
above the surface of the water like an aroused porpoise, is one that 
returns to me in idle moments such this.  What else would a Lucas
torpedo do but try to fly?

--Scott "Just when you thought it was safe to get out of the water" Fisher



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