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