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Re: Parachute lines

To: Wester S Potter <wspotter@jps.net>
Subject: Re: Parachute lines
From: Ed Van Scoy <edvs@uswest.net>
Date: Tue, 07 Nov 2000 21:09:18 -0700
Wes;
Just curious, do you think the catch-net would have stopped Burkland?
Ed


Wester S Potter wrote:

> Howard, List.
> The thing that disturbs me is that even after several years there are still
> tethers that can't handle the stress and snap so cleanly.  I'm aware of the
> programming Deist does and the results have been impressive in stopping so
> many cars so many times, safely.  What scares me is the fact that with the
> potental of eight or so 'liners capable of 400 mph speeds this next year.
> This should bring the probable result of two way record runs again.  On the
> South end of the course there won't be mud for stopping.  We don't need more
> "Breedlove stops" in a pond somewhere or someone running into a dike.
> As for a kevlar tether, the strength isn't necessarily longitudinal from
> what I have been able to read ... the impact resistance is based on a
> cushioning effect from the woven layers, of which there are several (and the
> friction between them is the shock absorbing quality), and the strength of
> the covering surfaces.  Ballistic nylon is just that, ballistic, tough
> enough to slow the original hit
> What is needed is some strapping that will hold up under the shock of the
> chute deployment jerk.  As an example, Polypropylene rope is stronger in
> some ways than nylon for the same number of strands and same thickness of
> strands.  There must be some composite that could be core-spun or
> multi-fiber cording that could be manfactured to handle the load.
> Just brainstorming and I'm probably all wet but I'm very concerned about the
> potential for a dangerous situation.
> Wes
>
> PS  ...  We once towed a '50 Chev 2 door for thirty five miles on a very
> cold winter night using two strands of nylon shroud line from a parachute.
> The stuff is great until it gets a solid hit, as long as it can stretch a
> bit it's just fine.
>
> W

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