I have no intention of getting into any exchange with Derek who has a
profoundly biased view of winch launch. There is a substantial body of
engineering measurements and expert opinion that contradicts just about
everything Derek has to say. Knowledgeable people just ignore him since his
prupose is just to start arguments.

His favorite winch (Which he serves as the chief cheerleader - probably to
the great embarassment of the maker.) exibits huge tension oscillations
which have been measured by logging tensionmeters. These oscillations are
easily felt and disturbing to all pilots - except Derek who seems somehow
unable to notice them. If you want to see tension logs of these
oscillations, contact me privately. I can link anybody to videos showing
this winch downshifting and breaking winch ropes.

I can assure everyone that Frank Whiteley can read an engine tachometer
better than just about anybody. There was no overrevving of the Faribault
winch, it was simply geared too tall to use 3rd gear. Using second gear
also eliminated the surging 3-2 downshift near the top of the launch.

Bill Daniels


"Derek Copeland" wrote in message
...
We don't seem to get 'tension oscillations' using basically similar
winches in the UK! Deliberately launching in second gear sounds like a
good way of over-reving the winch engine or running out of available cable
speed, unless there is a reasonable headwind. Perhaps Bill should have a
word with our gearbox supplier? We just launch in 'Drive' without
experiencing any of these problems!

We weren't told how long the winch run was, but I note that Bill felt
that 1500ft launches were usually high enough for contacting thermals.
That also mirrors our finding on this side of the pond. More height is
alway welcome though!

Derek Copeland


At 15:39 23 May 2008, Bill Daniels wrote:

"John Scott" wrote in message
...
What type of winch was being used?

John Scott


It was an ex-Canadian Gerhlein style single drum winch with a Chevy 350
V8

and a GM TH400 series transmission. It's a well maintained example of a

1960's style winch. It's not ideal but cheap enough to get started
with
winch launch. The ~1500' AGL launches it delivered were just fine for

contacting thermals. Had we not been in training mode, I could have
thermalled away on almost every launch.

The power was just right to allow the glider pilot to control airspeed
with
pitch inputs but it did exhibit tension oscillations whenever the launch
was
disturbed by a rough gear change or thermals as is typical with this
type
of
winch. We were able to reduce oscillations by using 2nd gear. 2nd gear

also eliminates the tendency for the TH400 to make a 3 - 2 downshift near

the top of the launch.

A modern tension controlled winch would probably increase the release
heights to 2000' AGL by holding rope tension nearly perfect.

Bill Daniels