SAFE Winch Launching

On Jul 14, 4:34*pm, Gary Emerson wrote:
Just exacly where are you making these tensions measurements????

Are you making them at the weak link??

Are you making these measurements at the winch end of things?

I'd really like to know...

Most people are using a "logger" that works like a GPS logger except
that it measures tension with a load cell and records the data on
flash memory card at a few samples per second for later readout on a
PC. With it's protective padding, It's about the size of a toy
football or a liter soft drink bottle and weighs less than a pound.
It's placed in the winch line near the parachute. I'm not an EE, but
I'm told they are easy to make using off the shelf components - any
"sparky" can build one. It's nice since you can use it on any winch.

You can also measure it at the winch if it's hydraulic or electric or
you use a Running Line Tensiometer (RLT).

A large drum has relatively little rope build-up during a launch so
the effective radius can be estimated pretty closely as a function of
time. With a hydraulic winch, the torque at the drum is directly
related to the oil pressure at the hydraulic motor. With those data,
the rope tension can be calculated to more than good enough accuracy.
It's the same with an electric winch except you measure electrical
values.

No matter how you get it, a tension trace is very useful in diagnosing
problems with a winch - or a winch driver. I'd want to make my own
trace on any winch before I bought it.

On Jul 15, 12:45*pm, tommytoyz wrote:
Andreas,
At my old club in Germany there were several prices depending if you
were a youth, club member in club aircraft, club member with your
private aircraft or non club member with your private aircraft. The
cheapest rates are as you mentioned. It also makes a big difference
that the German clubs have way more launches than 30 a week. It's more
like 150 a week or more. So the spread can be less.

Of course there are other criteria that the government supports these
clubs and some members to a small degree and they also charge by the
hour for their aircraft - though a small fee - but a fee none the
less. Their set up is just totally different, but *my point is that
you can make good money as a club here in the USA with a winch where
you really can't with a tow plane. The tow plane is just very
expensive if operated by the club and if using an FBO, no money comes
back to the club.

All this changes, with a club owned winch and even charging the
astronomical fee (for a winch launch) of $15 per launch, it's a good
money maker which can be put to good use in a non profit 501 (c)(3)
club to buy aircraft, equipment, hangars, etc.....Even at $10 a launch
it's a good money maker. Perhaps the launch fees can be charged as in
the German clubs, depending on club status and aircraft. This would
encourage club membership as well as it's cheaper to launch as a club
member.

You mention gov't support in Germany, but in effect that's what a 501c
(3) tax determination provides in the US. That is, the non-profit tax
determination is a means to keep the size of government at bay, yet
support your voluntary efforts for something that might not exist
locally apart from that volunteerism. The benefit comes from the
donors, and the donors benefit also and it reduces taxes.

A US club could do 150 per week, but you have to work at recruiting to
the sport and plan for the results of your efforts.

Club's are generally good at keeping logs of glider time, so why not
charge for air time. In the UK, they charged by the minute at the
clubs I joined. In the RAF clubs, the first ten minutes were free and
the meter was running (very modestly) after that. The book keeping is
hardly difficult these days.

Frank Whiteley

Bill,

Just out of interest, who are these 'most people' and do they have a
design for a tension logger that could published? I know of only one club
in the UK who have tried using one, which was the source of your infamous
'ugly tension spikes' claim.

I have looked at these logs and they tend to show momentary troughs rather
than spikes, and the weak link strengths were generally not exceeded.
Without knowing what the meteorological conditions where at the time, or
how smooth the winch driver and the glider pilot where in their actions,
it is difficult to draw any conclusion from them. I haven't yet seen a
trace from your 'US superwinches', so can you prove they would do any
better in the same circumstances and with the tension logger mounted in
the same place?

Derek Copeland

At 03:50 16 July 2009, bildan wrote:
On Jul 14, 4:34=A0pm, Gary Emerson wrote:
Just exacly where are you making these tensions measurements????

Are you making them at the weak link??

Are you making these measurements at the winch end of things?

I'd really like to know...

Most people are using a "logger" that works like a GPS logger except
that it measures tension with a load cell and records the data on
flash memory card at a few samples per second for later readout on a
PC. With it's protective padding, It's about the size of a toy
football or a liter soft drink bottle and weighs less than a pound.
It's placed in the winch line near the parachute. I'm not an EE, but
I'm told they are easy to make using off the shelf components - any
"sparky" can build one. It's nice since you can use it on any winch.

You can also measure it at the winch if it's hydraulic or electric or
you use a Running Line Tensiometer (RLT).

A large drum has relatively little rope build-up during a launch so
the effective radius can be estimated pretty closely as a function of
time. With a hydraulic winch, the torque at the drum is directly
related to the oil pressure at the hydraulic motor. With those data,
the rope tension can be calculated to more than good enough accuracy.
It's the same with an electric winch except you measure electrical
values.

No matter how you get it, a tension trace is very useful in diagnosing
problems with a winch - or a winch driver. I'd want to make my own
trace on any winch before I bought it.

Just to emphasize John's point about a properly set up automatic gearbox
giving smooth and imperceptible gear changes during a winch launch, see if
you can hear the gearchanges in this video of a new Skylaunch winch in
action at Lasham?

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

Derek Copeland

At 19:34 11 July 2009, johngalloway wrote:
On 11 July, 14:36, bildan wrote:

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.
=A0With
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. =A0They are not particularly well
controlled since they use road vehicle torque converters and automatic
transmissions free to shift gears when they please. =A0The 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 some 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

On Jul 19, 4:30*am, Derek Copeland wrote:
Just to emphasize John's point about a properly set up automatic gearbox
giving smooth and imperceptible gear changes during a winch launch, see if
you can hear the gearchanges in this video of a new Skylaunch winch in
action at Lasham?

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

Derek Copeland

Opening the throttle like a little old lady will mask shifts on any
transmission. This obviously depends a great deal on the winch
operator opening the throttle very gingerly.

On 19 July, 16:54, bildan wrote:
On Jul 19, 4:30*am, Derek Copeland wrote:

Just to emphasize John's point about a properly set up automatic gearbox
giving smooth and imperceptible gear changes during a winch launch, see if
you can hear the gearchanges in this video of a new Skylaunch winch in
action at Lasham?

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

Derek Copeland

Opening the throttle like a little old lady will mask shifts on any
transmission. *This obviously depends a great deal on the winch
operator opening the throttle very gingerly.

Bill,

You seem to have difficulty coping with the fact that whatever
preconceived idea comes into you mind is not necessarily a fact.

The fact is that

On 19 July, 16:54, bildan wrote:
On Jul 19, 4:30*am, Derek Copeland wrote:

Just to emphasize John's point about a properly set up automatic gearbox
giving smooth and imperceptible gear changes during a winch launch, see if
you can hear the gearchanges in this video of a new Skylaunch winch in
action at Lasham?

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

Derek Copeland

Opening the throttle like a little old lady will mask shifts on any
transmission. *This obviously depends a great deal on the winch
operator opening the throttle very gingerly.

Bill,

You are implying that if the throttle of a Skylaunch winch is advanced
rapidly then the autobox changes will become obvious or a problem or
whatever. This is simply not the case.

At various times I have test driven a Skylaunch, been inside and
outside the winch looking out for gear changes (because this was
something I was initially wondering about too), and been launched. I
have seen the throttle advanced rapidly to maximum or advanced slowly
over 3 seconds and it makes no difference to appreciation of
gearchanges. As a personal example I had a launch recently in which
the driver (watched by a friend in the cab) for some reason pushed the
throttle rapidly through the throttle stop guide for my type and gave
me a very overpowered initial acceleration. There was absolutely no
detectable gear change effect during the initial (very rapid)
acceleration.

John Galloway

On a very still day the gliders up to DG1000Ts were being accelerated by
the Skylaunch winch from zero to lift off speed (50-60mph) in about 3
seconds, which is little slower than Bill claims for his US superwinch.
Any faster than this can be dangerous for some types of glider, because it
can cause excessive pitch up rates. Excessive acceleration can also bang
down the tails of those gliders that set on their nose wheels or skids
pretty hard onto the ground, with a risk of structural damage!

Derek Copeland

At 18:31 19 July 2009, johngalloway wrote:
On 19 July, 16:54, bildan wrote:
On Jul 19, 4:30=A0am, Derek Copeland wrote:

Just to emphasize John's point about a properly set up automatic
gearbo=
x
giving smooth and imperceptible gear changes during a winch launch,
see=
if
you can hear the gearchanges in this video of a new Skylaunch winch
in
action at Lasham?

http://www.youtube.com/watch?v=3DriqhzcXZqzg

Derek Copeland

Opening the throttle like a little old lady will mask shifts on any
transmission. =A0This obviously depends a great deal on the winch
operator opening the throttle very gingerly.

Bill,

You seem to have difficulty coping with the fact that whatever
preconceived idea comes into you mind is not necessarily a fact.

The fact is that

At 19:18 19 July 2009, johngalloway wrote:
On 19 July, 16:54, bildan wrote:

Opening the throttle like a little old lady will mask shifts on any
transmission. =A0This obviously depends a great deal on the winch
operator opening the throttle very gingerly.

Bill,

I am a little mystified by this, can you tell us Bill exactly how many
Skylaunch winches you have seen, which particular types, and how many
launches you have witnessed being made by a Skylaunch winch?

At 20:00 19 July 2009, Del C wrote:
On a very still day the gliders up to DG1000Ts were being accelerated by
the Skylaunch winch from zero to lift off speed (50-60mph) in about 3
seconds, which is little slower than Bill claims for his US superwinch.
Any faster than this can be dangerous for some types of glider, because
it
can cause excessive pitch up rates. Excessive acceleration can also bang
down the tails of those gliders that set on their nose wheels or skids
pretty hard onto the ground, with a risk of structural damage!

Derek Copeland

Not if you hold the tail down to prevent that happening. In theory the
faster the acceleration to flying speed the safer the launch, having
effective controls makes all the difference. Being towed down the field on
the ground accelerating slowly is a recipe for disaster.