SAFE Winch Launching

On Sat, 11 Jul 2009 17:07:50 -0700 (PDT), bildan
wrote:

A tension controlled winch will do the opposite - decreasing power in
thermals letting lift do the work and increasing it in sink leaving
the pilot to control speed with pitch. The pilot sees a very smooth
launch regardless of wind or thermals. The winch operator doesn't
need to do anything at all.

It's wonderful to never need speed signals again.


.... yet thousands of clubs in Europe with much, much more winch
experience than any club in the US don't see the need for such a
system.

Bills explanation a couple of posts ago is an excellent and simple
description of how it constant tension works and why it would be
beneficial.

Why don't we in Europe adopt this technology -- quite simply cost.
Without private finance of money/time/labour/parts few clubs if any can
afford to scrap their current winches and buy the new technology.

Dave

At 00:29 12 July 2009, Andreas Maurer wrote:
On Sat, 11 Jul 2009 17:07:50 -0700 (PDT), bildan
wrote:

A tension controlled winch will do the opposite - decreasing power in
thermals letting lift do the work and increasing it in sink leaving
the pilot to control speed with pitch. The pilot sees a very smooth
launch regardless of wind or thermals. The winch operator doesn't
need to do anything at all.

It's wonderful to never need speed signals again.


.... yet thousands of clubs in Europe with much, much more winch
experience than any club in the US don't see the need for such a
system.

On 12 Jul 2009 10:15:03 GMT, Dave Martin
wrote:

Bills explanation a couple of posts ago is an excellent and simple
description of how it constant tension works and why it would be
beneficial.

Why don't we in Europe adopt this technology -- quite simply cost.
Without private finance of money/time/labour/parts few clubs if any can
afford to scrap their current winches and buy the new technology.

If constant tension was really necessary for a good winch launch, many
clubs would already have one.
But the standard system (Tost, Skylaunch, whatever) is good enough for
the majority aof the clubs here.

It's definitely nicve to have - but Bill would probably have an easier
job if he advertized a more simple and much cheaper winch design to
the US clubs...

Hi,

A tension controlled winch will do the opposite

... yet thousands of clubs in Europe with much, much more winch
experience than any club in the US don't see the need for such a
system.

Some do.

When I was trained as a winch driver I was taught to judge cable tension
and use that as the input parameter to the control loop. The only way of
doing that without special sensors is to look at the cable sag. Works
during the main portion of the launch, but is not very accurate of course.

I think if the winch, or winch driver, has the means to control tension
and the pilot controls airspeed winch launches become more efficient and
even safer. Reports suggest that, I have no experience of my own.

Also you would propably get much more consistent launch performance
across different conditions and much more important, different drivers.
Today we get launches like being shot from a carrier deck and the
lumbering wingrunner-testing type all in the same day depending on who
is manning the winch. The first launches of the day, or after a driver
swap, or when conditions change would no longer need to be different
than those by a well-adapted driver.

I am all for it.

Ciao, MM

At 00:07 12 July 2009, bildan wrote:

If a glider encounters a thermal during a launch, the rope tension
will increase which the automatic transmission will see as a "hill"
causing it to increase torque to the drum. This increases rope
tension still more as it tries to pull the glider down through the
thermal. If the glider hits sink, the automatic transmission will
slack off the torque just when the glider needs more power. A good
winch operator can overcome these to a degree with constant throttle
adjustments - if he can tell what is going on in the glider but it's
hard, skilled work. It's definitely not "set and forget".

A tension controlled winch will do the opposite - decreasing power in
thermals letting lift do the work and increasing it in sink leaving
the pilot to control speed with pitch. The pilot sees a very smooth
launch regardless of wind or thermals. The winch operator doesn't
need to do anything at all.

It's wonderful to never need speed signals again.


I think the difference in design concept between Europe/ USA is that over
the years we have leaned to design things which work for a minimal cost.
We have tried to avoid the expensive solution designed to kill you. I can
think of nothing more dangerous in a winch design than a tension sensitive
drive.

It may be wonderful to not need signals again, which if you are dead of
course you don't need, we prefer the safe option over here even if it
means a little more work.

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.

On Jul 12, 8:45*am, Don Johnstone wrote:
At 00:07 12 July 2009, bildan wrote:



If a glider encounters a thermal during a launch, the rope tension
will increase which the automatic transmission will see as a "hill"
causing it to increase torque to the drum. *This increases rope
tension still more as it tries to pull the glider down through the
thermal. *If the glider hits sink, the automatic transmission will
slack off the torque just when the glider needs more power. *A good
winch operator can overcome these to a degree with constant throttle
adjustments - if he can tell what is going on in the glider but it's
hard, skilled work. *It's definitely not "set and forget".

A tension controlled winch will do the opposite - decreasing power in
thermals letting lift do the work and increasing it in sink leaving
the pilot to control speed with pitch. *The pilot sees a very smooth
launch regardless of wind or thermals. *The winch operator doesn't
need to do anything at all.

It's wonderful to never need speed signals again.

I think the difference in design concept between Europe/ USA is that over
the years we have leaned to design things which work for a minimal cost.
We have tried to avoid the expensive solution designed to kill you. I can
think of nothing more dangerous in a winch design than a tension sensitive
drive.

It may be wonderful to not need signals again, which if you are dead of
course you don't need, we prefer the safe option over here even if it
means a little more work.

Check your geography. Tension controlled winches were developed in
Europe. Check your engineering facts. Tension controlled winches are
FAR safer than any other alternative.

How can a winch be safe when the operator must control glider airspeed
with throttle WHEN HE HAS NO KNOWLEDGE OF IT? Actually, Skylaunch
indirectly acknowledges this by offering airspeed telemetry as an
option.

The only reason for this loud controversy is a single English winch
manufacturer in who uses cheap American auto parts and sells the
product - essentially a 2-drum Gerhlein - for $145,000 USD at last
check. It's a great business model as long as there are suckers.
People tend to get upset when you point out the Emperor has no
clothes.

Yes I know it's a MARINE GM V8 but that's the same engine core as used
in a pick-up trucks with a few different accessories. Last check,
they wholesale for about $2,500. The stock GM TH400 sells for about
$1200 USD.

On Sun, 12 Jul 2009 10:28:03 -0700 (PDT), bildan
wrote:


How can a winch be safe when the operator must control glider airspeed
with throttle WHEN HE HAS NO KNOWLEDGE OF IT?

It is safe. Period. Even if you don't believe that.


All the best
Andreas

On Sun, 12 Jul 2009 12:45:08 +0200, Marian Aldenhövel
wrote:


... yet thousands of clubs in Europe with much, much more winch
experience than any club in the US don't see the need for such a
system.

Some do.

Indceed some do - but very, very few.
If there really was an urgent need we'd have more than a couple of
such winches in Europe by now, don't you agree?

When I was trained as a winch driver I was taught to judge cable tension
and use that as the input parameter to the control loop. The only way of
doing that without special sensors is to look at the cable sag. Works
during the main portion of the launch, but is not very accurate of course.

But sufficiently accurate, isn't it?
Contrary to the believe of some people here it doesn't matter if the
speed during the winch launch is 5 kts faster or slower (although the
perfect speed certainly increases launch height).

I think if the winch, or winch driver, has the means to control tension
and the pilot controls airspeed winch launches become more efficient and
even safer. Reports suggest that, I have no experience of my own.

Efficiency? Definitely.
Safety? I doubt it.
I havent't been able to find even one accident report that was caused
by inappropriate power setting by the winch driver, yet there are
comparably many accidents caused by rope breaks or complete power
losses of the winch - things that cannot be prevented by tension
controlled speed.


Also you would propably get much more consistent launch performance
across different conditions and much more important, different drivers.

Indeed. Nice to have.

Today we get launches like being shot from a carrier deck and the
lumbering wingrunner-testing type all in the same day depending on who
is manning the winch. The first launches of the day, or after a driver
swap, or when conditions change would no longer need to be different
than those by a well-adapted driver.

Typical problem of winch driver training. Once we started to re-train
our winch drivers who had problem scontroling the speed, we got rid of
this problem.


Viele Grüße
Andreas

I would love to fly a tension controlled winch we were launhing today in
to strong head winds increasing rapidly part way up the launch. I can
imagine it is better, but I am not an expert.

Winch safety is mostly in the hands of the pilot, the winch is not
relevant to a good launch, but the trained pilot must be able to react to
any scenario.

But other nonsense posted here . please help me, ...

A standard car auto gearbox has some magic power to automatically adjust
the torque to the car wheels on reaching a hill, without changing gear,
road speed or engine setting? What magic is that?

David.


At 18:45 12 July 2009, Andreas Maurer wrote:
On Sun, 12 Jul 2009 12:45:08 +0200, Marian Aldenhövel
wrote:


... yet thousands of clubs in Europe with much, much more winch
experience than any club in the US don't see the need for such a
system.

Some do.

Indceed some do - but very, very few.
If there really was an urgent need we'd have more than a couple of
such winches in Europe by now, don't you agree?

When I was trained as a winch driver I was taught to judge cable tension

and use that as the input parameter to the control loop. The only way of

doing that without special sensors is to look at the cable sag. Works
during the main portion of the launch, but is not very accurate of
course.

But sufficiently accurate, isn't it?
Contrary to the believe of some people here it doesn't matter if the
speed during the winch launch is 5 kts faster or slower (although the
perfect speed certainly increases launch height).

I think if the winch, or winch driver, has the means to control tension

and the pilot controls airspeed winch launches become more efficient and

even safer. Reports suggest that, I have no experience of my own.

Efficiency? Definitely.
Safety? I doubt it.
I havent't been able to find even one accident report that was caused
by inappropriate power setting by the winch driver, yet there are
comparably many accidents caused by rope breaks or complete power
losses of the winch - things that cannot be prevented by tension
controlled speed.


Also you would propably get much more consistent launch performance
across different conditions and much more important, different drivers.


Indeed. Nice to have.

Today we get launches like being shot from a carrier deck and the
lumbering wingrunner-testing type all in the same day depending on who
is manning the winch. The first launches of the day, or after a driver
swap, or when conditions change would no longer need to be different
than those by a well-adapted driver.

Typical problem of winch driver training. Once we started to re-train
our winch drivers who had problem scontroling the speed, we got rid of
this problem.


Viele Grüße
Andreas