I understand that the Van Gelder (MVG) winch at Dunstable (UK) is taken out
of service for half a day each week for routine maintenance and for one
week a year for a major overhaul. This done during their competition week
when they only aerotow.

In comparison, the Skylaunch is much like a modern automobile in that you
just check the levels and give it a daily inspection (DI) every day, and
change the oil, filters and the cables every so many thousand launches.

One of the reasons Lasham decided to change from Tost to Skylaunch (apart
from better launches) was that our long serving maintenance engineer
reached retirement age and the Tosts required quite a lot of servicing and
maintenance, and an annual rebuild which took about a month each. We did
these in the winter, but we still operate then, so if anything went wrong
with the winch in service we had no backup.

When we first started winch launching we tested a 6-drum MVG winch, which
as a driver I found really impressive with lots of flashing lights and
hydraulic and pneumatic systems. However it was very expensive and it was
felt that it was rather putting all our eggs in one basket. Particularly
when we (not me BTW) had a foul up which wrapped a cable many times around
the common drive shaft and put the whole thing out of operation for nearly
two hours. In the end we decided to buy two much more basic two drum Tosts
on the grounds that if you had a major foul up or a problem on one, you
could continue to launch with the other.

Incidentally I believe that the World Record height for a glider winch
launch (over 1500m) is currently held by the relatively simple MEL Leopard
winch, and was previously held by a slightly modified Tost fitted with
higher capacity drums. See:

http://www.youtube.com/watch?v=zFKsjDIjmDg

http://www.youtube.com/watch?v=-VlRd9-wxQI

Derek Copeland


At 22:45 27 July 2009, Don Johnstone wrote:
At 20:39 27 July 2009, Bruce wrote:
Look at what MEL does -

http://www.machinefabriek-el.nl/content_16.asp

This is the manufacturer to the reasonably conventional "Leopard"
winch

and of the "van Gelder" - probably the most sophisticated winch
actually
working.

I wonder what proportion they are made in.

But anyway - as examples.
Note the engines are Volvo Penta diesel...
And they measure lots of things, and still get manually driven - albeit

with exquisite control.

Interestingly there are reports of clubs reverting from van Gelder to
Skylaunch (or equivalent) with retrieve setups with better launch
rates.

Something to do with complexity and maintainability and cost. Any one
with actual experience?

Bruce

I flew off a Munster Van Gelder winch for 10 years and when it was
working
it gave the smoothest launches I have ever had. It was fitted with
automatic drum engagement which was permanently switched off as the
drivers could do the selection much more efficiently. The control
systems
were very very complex and it required many hours of maintenance during
the week to make sure it would run for the weekend. If it had been a
private club it would never have worked but the Royal Air Force had the
manpower to keep it maintained. Despite this many of the advanced
systems
did not work. The winch drivers however were well trained and in the
main
skillful so they worked round many of the minor problems. The winch was
a
perfect example of a complex and technically advanced machine which did
not stand up to the rigors of being operated in the real world, it was
just too complex. Following that I flew for 7 years at a club using a
Skylaunch. The ability to accelerate the glider was not much less than
the
MVG but it was nowhere near as smooth. The engineering was simple, one
could say agricultural, but that was it's main saving, there was
nothing
complex to go wrong. The winch was made up of well tried and test
indusrty
standard units which worked even with minimal servicing and I do mean
minimal. The only critisism I would make is that some of the engineering
was not agricultural enough to stand up to the abuse of club member
winch
drivers. Bits fell off from time to time but the the winch engine,
transmission and drums continued to work and work well.

The MVG winch and the Skylaunch winch do the same job but the MVG does
it
with much less effort. The MVG has 6 drums and it was a minor miracle if
they were all available for use. It drank deisel like there was no
tomorrow.
The Skylaunch has two drums and you could purchase 2 Skylaunch winches =
4
drums for the same amount the RAF paid for the MVG 15-20 years ago.

My current club operates a Supercat winch modified by Skylaunch to take
their engine, transmission and control. It is certainly as good as a
standard Skylaunch and has almost no downtime. They all run on LPG.
(It's
what passes for cheap fuel in the UK)
With winches I believe that the KISS principle is essential