Has anyone approached the rope suppliers for some developement funding
I would think that to enlarge their market that some funds could be
allocatted
possibly from their advertising budget since they don't have to advertise to
gain
clients.
gary
"Bob Johnson" wrote in message
...
Hello Bill --

In an attempt to summarize the search for an effective synthetic rope
guillotine then, I would say that we are expecting to develop an
emergency line cutter at least as effective and safe as those we
already employ against steel lines, stranded and solid, moving and
stationary.

Since the numerous winch builders and users on your side of the pond
will by necessity be building and rigorously testing an ideal unit
fairly soon, we'll be interested in learning of your solution(s) to the
problem!

I personally favor trying a "cigar cutter" powered by a compressed gas
cylinder. The cutting blade could be veed to gather the line into the
stationary blade and suitable finger guards can be added to prevent
injuries. The actuating cylnder diameter can be made as large as
necessary to multiply the bottle force enough to secure a successful
cut. Also, at least two units could be installed to provide a backup.

In the oilfield we use diaphragm operated rising stem valves that could
be adapted for trials by developing a new valve "trim". A typical 6-inch
diaphragm valve would have about 25 sq in of area. Powered by only a 100
psi cylinder, around 2500 lb of downward force would be available to the
descending stem. That ought to cut something.

A plus is that the valve body could have short pipe nipples screwed onto
each end, rendering personal injuries a non-issue. These nipples could
also be used to secure the unit the the winch by use of heavy duty pipe
clamps. Finally,the higher the pressure, the larger the gas cylinder and
the smaller the diaphragm, the faster the unit would operate.

BJ

"W.J. (Bill) Dean (U.K.)." wrote:

As I am sure Dave Martin knows there was another accident in the U.K.
where
the cable got round the glider's wing after the glider had released it.

The winch driver operated the cutter while the glider was still drawing
the
cable out, which did not succeed in cutting the cable; the winch driver
was
left with nothing else he could do, then the cable hung up, tightened,
and
the pilot was killed.

So here was a case where it was necessary to cut the cable when it was
moving.

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.


"Dave Martin" wrote in message
...

Bob

I think Marcel answered your questions

I can think of and know of instances where the winch
driver should cut the cable instantly, moving or stationary.

Should -- must -- need -- want -- ought to cut the
cable are all subjective and cannot be answered fully
in the space available. Ultimately I suppose on which
side of the incident you are sitting, on the winch
or in the air and the final outcome.

I witnessed an incident where the pilot on a winch
launch failed to take the correct action when travelling
too fast, he released and accelerated flying under
the cable which then wrapped itself round the glider.
Removed the tail plane and embedded itself in the
fin

The glider did a neat 180 and then dived at about 45
degrees earthwards. The winch driver did not cut the
cable. Just before the glider hit the ground, the winch
cable pulled tight and stopped the glider in mid air.
It 'landed' with greatly reduce forward speed and
energy. It hit the ground almost flat.

The glider was wrecked but the pilot lived.

Talking to the winch driver afterward, he failed to
cut the cable because events happened so fast, he froze.
It was probably all over in less than 10 seconds.

Whatever the incident, the winch driver MUST have the
facility to cut the rope. Only hindsight will tell
whether he should have or should not have cut the cable.

The answer to the problem is training the brain on
each end of the wire to treat the wire and the winch
with utmost respect.

Dave Martin