"goneill" wrote in message
...
Other info now obtained
poly is 10 millimetres diameter and with use shrinks to 8ml
Durability is 1000-1500 launches on grass field being dragged out
by 4wd from stationary winch
Our local cost is $245US for 1000metres of rope.DO THE MATH.ITS CHEAP
We charge round $8US per launch this to help fund another winch
The winch motor is a 5.7ltr V8 petrol driving through an auto box to an
old truck axle with diff modified to drive one side at time (your common
winch)
The difference is the drums.The drums have a centre core cut from the old
front wheel
of a road roller 12ml thick hardened steel (we got it for free)and the
side
plates
10ml thick with a welded on bevel at the top to act as a guide.
All this to stop the crushing effects.of the stretched rope
I have the email of one of the main members who helped in the
experimentation stage
and is on the instructor,s panel so can explain the changes to the flight
training on
winch launching with our style of winch.
Another club has also switched to this method and is having the same
success
as we are on a similar strip length.Most single seaters are getting close
to
or +50% of
rope length in height.
Trials at another club with 5400ft of runway found that the sag in the
rope
with longer
lengths tended to get premature releases in top third of launch as angle
of
the rope
into the release was not as flat.
This was a limited number of launches.
gary

Gary,

Thanks for the information. Now, if the poly could be spliced ~50/50 or so
with something like 1/8" Validator 12
http://www.samsonrope.com/admin/data...dator12_LR.pdf ,
(Vectran) http://www.pelicanrope.com/peli05c.htm both the bungee and sag
effects could be reduced with some cost benefits. This could be a solution
for long runs. When we launched with 1000ft of Spectra on the end of the
wire rope, we didn't pull the Spectra through the rollers. Two synthetics
with a reasonable join might work well as a hybrid solution.

Vectran is stronger than Spectra with a higher critical temperature, but
with somewhat less abrasion resistence.

There are some interesting 1/4" vectran sheathed products
http://www.pelicanrope.com/new04.htm
for improved abrasion resistence.

And Plasma 12
http://www.cortlandcable.com/psrope/...PlasmaRev9.pdf
Spectra in a variety of sizes.

Frank Whiteley
Colorado