It would seem like a vintage 125 dirt bike shock
would be just the thing for that. They have nice
long travel and a good progressive rate beginning
the first inch or so of compression with about
twenty pounds and increasing to 500+ pounds
before they bottom out. Use a 2:1 arm and it
should never reach bottom-out. Migth be a good
engineering experiment coming out of this.
Dick J
--- Dave <ddahlgren@snet.net> wrote:
> Thinking a little outside the box today.. I
> wonder if a spring and shock
> arrangement on a rocker system would soften the
> hit of the chute.. If
> you connect the chute line to a pull rod or
> rods and then go through a
> rocker arrangement you could push on a spring
> and shock (coil over type)
> and thereby take up the hit a lot softer. the
> same as driving with a
> solid suspension everything breaks or cracks
> from all the instantaneous
> loads. i see no reason why this could not work
> very effectively.. If
> you know the speed and mass of the car and the
> square ft. of the chute i
> would think that an appropriate spring rate and
> damping rate could be
> calculated so the chute does not just bang open
> and tear things up.
> Might even make some of the hard to handle cars
> a little smoother
> too.... I am open for further discussion on
> this.
> Dave Dahlgren
>
> 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
=====
* * * * * * * * * * * * * *
* Dick J *
* (In East Texas) *
* # 729 *
* C/GRS C/FRS D/STR *
* * * * * * * * * * * * * *
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