Winch launch clinic at Faribault, Minnesota

"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

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

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

I am a senior instructor at a major UK gliding club and regularly take
winch launches on Tost and Skylaunch winches, which both have large
capacity GM Marine V8 engines and TH400 changing 3 speed automatic
gearboxes. To me, and everyone else who launches on them, they give smooth
and safe launches. The Skylaunch is the preferable design as it is much
more modern and fitted with a semi-automatic form of launch control. The
Tost is purely manually controlled. Please see the following videos as
examples of this: The one winch launch failure was simulated by the
gliding instructor as a training exercise BTW:

http://www.youtube.com/watch?v=FCQTkCFqLjc
(Tost)

http://www.youtube.com/watch?v=F2SD7USG1n4
(Tost and Skylaunch)

http://www.youtube.com/watch?v=HNcEtvcnnGc
(Skylaunch)

Derek Copeland

At 16:21 24 May 2008, Bill Daniels wrote:
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