Nick Hull wrote:

In article ,
"J. Clarke" wrote:


Another way would be to use a pyrotechnic cutter--they're purpose made
for this kind of thing.


A safe pyro cutter could be made from a rope wrapped in common smokeless
gunpowder. Ignition by a common model rocket igniter.

Might take some work to keep the powder in place under strain and get the
charge right to make a reliable cut on webbing heavy enough to trust with a
car, but could be done.

The kind used in parachutes are self-contained and can be mechanically or
electrically triggered. If you hold one in your hand and trigger it you'll
want to let it go _real_ fast (they get hot) but it won't do you any
lasting harm. Put your finger in the ring line passes through, and then
trigger it and you _will_ lose that finger. Some are big enough to take a
small-framed person's arm.

--
--John
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(was jclarke at eye bee em dot net)