Bill,

I must admit that I have only ever seen one guillotine in pieces to carry
out the modification, and that was for a Tost winch when when we carried
out trials on UHMWPE synthetic cable. This is a spring loaded system in a
tube, activated by a lever in the cab pulling out a pin via a Bowden
cable. The steel fixed bottom element was replaced by a bronze equivalent
and that was it.

I should point out that our winches are maintained by professional staff
at Lasham, so I don't get much involved in that side of things. I am an
amateur gliding instructor and a winch driver, with 28 years of wire
launching experience.

Have you ever driven or had a launch on a Skylaunch winch? No, I thought
not! I think that you would be impressed if you did. It is easy to drive
and gives smooth, consistent and correctly speeded launches, unlike
anything I had launched on before. If it as bad as you keep claiming, why
have so many major European gliding clubs bought them, often in preference
to their own National products?

Usual disclaimers. I have no financial or other connections to Skylaunch,
other than being a satisfied user of their products.

Derek Copeland


At 19:38 24 July 2009, bildan wrote:
On Jul 24, 12:30=A0am, Derek Copeland wrote:
I assume that Bill's comment is intended to be yet another thinly
veiled
attack on Skylaunch, who make an excellent winch! There is no hard
evidence that rollers are any less Dyneema friendly, and in any case
Skylaunch can supply and fit swivelling pulleys if you think they are
better. Our new Skylaunch winches at Lasham are so fitted.

Again the rollers he is talking about are as fitted to antiquated US
Gerhlein winches, and his Ford Model T analogy is about right.

The guillotine issue is more relevant. For some reason hardened steel
blades that will chop steel cable many times are instantly blunted
when
used on any type of UHMWPE synthetic cable. I believe the fix is to
replace the anvil with a bronze component. So much for modern
materials
and technology!

Derek Copeland

At 23:39 23 July 2009, bildan wrote:

On Jul 23, 12:45=3DA0am, Derek Copeland =A0wrote:
Chris,

Nothing special required, except that the rollers or pulleys should
be
smoothed out and polished if they have been used for steel cable.
Some
types of drum may need to be reinforced as Dyneema can slip and
tighten
o=3D
n
the drum to the extent that it get crushed.

More spectacularly bad advice from Del C.

Smoothing and polishing rollers will NOT work since the rope slides
in
a helical path on the roller if the wrap angle is not exactly at
right
angles to the roller. =A0All roller designs used with 'plastic
rope'
show rings of melted plastic when used with Plasma Rope. =A0The rope
itself shows severe damage from melting. =A0Using rollers with Plasma
Rope is an expensive mistake

Plasma Rope (Spectra/Dyneema) should have swiveling pulleys with
specific pulley groove geometry. =A0I have a tested design for
fairlead
pulleys with a Plasma specific guillotine that I'll let anybody use
to
make their own. =A0E-mail me and I'll send the drawings.

It wasn't meant to be 'thinly veiled'.

Actually Derek's inexperience is showing. There is a difference
between guillotines for steel and Spectra/Dyneema in that the shearing
cutters used with steel won't cut "plastic rope". It doesn't
'blunt'
the blade, it just pushes them apart and defeats the cutting attempt.
Spectra/Dyneema is a lot tougher than steel.

You need a more aggressive guillotine with a "chopping" action that
forces a sharp steel blade against an anvil instead of a shearing
action. A steel edge cutting against a brass block works well as does
a plastic block which saves the edge.