On Jul 11, 1:34*pm, johngalloway wrote:
On 11 July, 14:36, bildan wrote:



On Jul 11, 2:00*am, Derek Copeland wrote:

At my club we typically get about 1600ft in no wind and

2000ft launching into a 10 knot headwind. Our standard aerotows are 2000ft,
but you can go as high as you like, depending on your needs and the depth
of your wallet.

This week we were getting as high as 1900' from 3900 feet of rope at
9000 feet density altitude with little wind with the Hydrowinch. *With
no gear shifting at all, the Hydrowinch is MUCH smoother than any
winch with an automatic transmission.

Skylaunches are just like old Gerhleins with new paint - they use
exactly the same components. *They are not particularly well
controlled since they use road vehicle torque converters and automatic
transmissions free to shift gears when they please. *The old junk
Gerhleins around most US clubs are probably the only winches in the
world worse than a Skylaunch - but they are a LOT cheaper.

BTW, notice how Derek has to reply to himself to get any conversation
at all?

This account of the performance of the Skylaunch winch is, as Bill has
repeatedly been told previously elsewhere by pilots who actually
operate or launch on Skylaunch winches, utterly false and his
obsessive denigration of it is disgraceful. *Our club had a Skylaunch
winch for evaluation for six days a couple of weeks ago. *The
smoothness of launch is faultless and a vast improvement over Supacat
and Tost winches

The fact that the automatic transmission can shift gears "when they
please" is a complete non issue. *The gear changes up at the start of
the launch occur within the first 2-3 seconds (timed by me) and before
the glider has rotated into the climb. *The gear changes are
completely imperceptible in the glider. *None of numerous pilots on
the ground near the winch during launches note the upwards gear
changes without being prompted to listen out for them - an even then
there was soe debate about whether they could be detected.
Occasionally the autobox changes down to second during the mid launch
when under load but at no time was any of the many pilots launched
aware of any gear change.

The operational mechanisms of the Skylaunch are not designed to
"control" the launch so it is not surprising that it does not do so.
What it does have is an interconnected maximum throttle position guide
that takes into account the type of the glider and the headwind
component. *This means that each glider is effectively provided with a
winch with an appropriately powered engine for itself and the wind
conditions in the mid launch. *The winch driver still has to control
the start and end of the launch - by advancing the throttle control at
an appropriate rate at the start (about 3 seconds IMHO) and backing
off the power at the top. *The predictable response of the good old GM
V8 to load means that the plot can pull into a steep climb without
fear of overspeeding.

The new US winches may turn out to be brilliant but Bill's emotional
bias invalidates him as an objective reporter in my opinion.

John Galloway

For the record, I have no financial or managerial connection with
either US winch manufacturer but I strongly support and encourage
both. Both chose the best solutions based on very careful
investigation of winch launch dynamics. Neither chose to spend money
on excessively complicated solutions without extremely good cause.

Do I have an emotional bias against crappy engineering? Damn right I
do - especially when it's being sold as the 'perfect' solution.

The use of an automobile engines and automatic transmissions has only
one advantage - they're cheap and they 'work' after a fashion but it's
far from an ideal solution. There is quite a bit of field data to
support this. Once the underlying dynamics is fully investigated, it
become clear that this is not the way to go. Automatic transmissions
are a particularly evil choice.

To repeat yet again, automatic transmissions are highly developed and
uniquely adjusted for each vehicle in which they are installed. To
transplant them into a glider winch with diametrically opposite
requirements brings out the worst in the device. They are designed
for a wildly different purpose.

People can get used to anything and will learn to compensate for the
shortcomings of a winch based on automobile parts. They may not even
realize they are compensating unless there is a point of comparison.
You may not notice the transmission shifting or tension/speed errors
until you launch from a winch that does not shift and automatically
adjusts for air motion - then it's a revelation.

I strongly suggest doubters read George Moore's article in July
Soaring and the following article in the September issue. Thanks to
George, we now know EXACTLY how winch physics work. It's no surprise
that such knowledge leads to new and better winch designs.