SAFE Winch Launching

Unless Bill has invented a perpetual motion machine, you can't get more
power out of a mechanical device (such as an automatic gearbox) than you
put in. You can gear that power down to get more torque, but the Skylaunch
winch depends on supplying the right amount of power (related to throttle
setting) for the given glider type and headwind component. The automatic
gearbox is only useful to provide some extra torque at low revs to get the
glider moving at the start of the ground run without stalling the engine.

Derek Copeland

At 22:45 12 July 2009, bildan wrote:
On Jul 12, 3:30=A0pm, David Chapman
wrote:

But other nonsense posted here . please help me, =A0...

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?


That 'magic' is called a torque converter which begins to slip and
multiply torque under increasing load. Stock units can double torque
to the wheels.

Modern transmissions use a torque converter locking clutch allowing an
even greater torque multipication factor after the clutch disengages
under load. The effect can be 4:1 or greater.

For basic info, see: http://en.wikipedia.org/wiki/Torque_converter

In addition, automobile engine torque curves have peak torque lower
than cruise RPM. As the vehicle encounters a load such as a hill, the
torque output actually increases as the RPM is pulled down by the
increasing load. The typical V8 used in glider winches has a torque
peak at about 1800 RPM.

The engine/transmission combination acts in exact opposition to what
is needed in a glider winch.

At 21:30 12 July 2009, David Chapman wrote:

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.

Bill Daniels has some very strange ideas as to how an automatic gearbox
works! As far as I am concerned, it is a device to allow a motor vehicle
to move off from rest, to smoothly change gears, and to stop without
stalling the engine, without a driver operated mechanical clutch. It is
not cruise control!

In that changing gear with a mechanical gearbox and clutch would give
dangerous short term losses of power, an automatic gearbox is an essential
component for any winch or towcar.

Derek Copeland

Bill

The arguments are now in an endless repetative cycle fired by the theories
you propose and the convenient practicalities of the European systems, also
used by older US winches - still in use today.

There is only one solution the challenge is there -- get the winch built
with the new technology and at a competetive price and put it on the
market.

Like new glider technology if it works people will use it.

Sadly much as we would like to do it we cannot change overnight.

Look how long it has taken to get the EB28 technology into a practical
aircraft --- but at what cost and how many of us can actually afford it?

Dave

At 07:15 13 July 2009, Derek Copeland wrote:
At 21:30 12 July 2009, David Chapman wrote:

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.

Bill Daniels has some very strange ideas as to how an automatic gearbox
works! As far as I am concerned, it is a device to allow a motor vehicle
to move off from rest, to smoothly change gears, and to stop without
stalling the engine, without a driver operated mechanical clutch. It is
not cruise control!

In that changing gear with a mechanical gearbox and clutch would give
dangerous short term losses of power, an automatic gearbox is an
essential
component for any winch or towcar.

Derek Copeland

On Jul 13, 1:15*am, Derek Copeland wrote:
At 21:30 12 July 2009, David Chapman wrote:

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.

Bill Daniels has some very strange ideas as to how an automatic gearbox
works! As far as I am concerned, it is a device to allow a motor vehicle
to move off from rest, to smoothly change gears, and to stop without
stalling the engine, without a driver operated mechanical clutch. It is
not cruise control!

In that changing gear with a mechanical gearbox and clutch would give
dangerous short term losses of power, an automatic gearbox is an essential
component for any winch or towcar.

Derek Copeland

The only strange part is your inability to read and understand
technical manuals. No one except yourself used the term "cruise
control". Automatic transmissions are extremely complicated devices
with complex behaviors that cannot be understood in your simple terms.

On Jul 12, 12:45*pm, 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

By those standards, starting cars with hand cranks was 'adequate' and
electric starters would be 'nice to have'.

In fact, tension control is relatively new technology based on vastly
increased knowledge of winch launch dynamics. It certainly has the
potential to increase safety in those cases where unexpected weather
or a human winch operator creates unexpected conditions.

At 23:01 12 July 2009, bildan wrote:


In fact, tension control is relatively new technology based on vastly
increased knowledge of winch launch dynamics. It certainly has the
potential to increase safety in those cases where unexpected weather
or a human winch operator creates unexpected conditions.


In fact it has the potential to be the most dangerous suggestion ever
encountered in glider winching.
Why is it that for years winches have been developed and used in the UK
and Europe with no real problems and all of a sudden someone comes up
with probably the most moronic suggestion ever and that is that if the
tension on the cable is increased the winch slows down to compensate.
So I leave the ground and the glider starts to rotate to the climb,
increasing the tension on the cable so it slows down. Brilliant, it takes
a real towering intellect to think that one through. I suppose the
explanation will be that there is some clever electronic gizzmo to
compensate. The problem with high technology systems is they do not tend
to be robust and they require regular maintainace to ensure their correct
operation, (MVG Winch is a perfect example, most of the advanced features
don't work) whereas a well trained winch driver can do the necessary
compensation using good old fashioned judgement far more safely.
I would far rather place my trust in a basic winch with a well trained
driver that rely on dubious untried engineering solutions driven by the
unknowing.
Skylaunch, Tost, Supercat and MVG winches perform very well with very few
problems. Skylaunch, or Skylaunch re-engined winches are probably now the
most popular winch in use in the UK. We like them and the many years of
experience that has gone into them.

PS We do not have deserts in the UK, and we don't cancel comps just
because 2 or 3 people don't get away either.

On Jul 12, 6:30*pm, Don Johnstone wrote:
At 23:01 12 July 2009, bildan wrote:



In fact, tension control is relatively new technology based on vastly
increased knowledge of winch launch dynamics. *It certainly has the
potential to increase safety in those cases where unexpected weather
or a human winch operator creates unexpected conditions.

In fact it has the potential to be the most dangerous suggestion ever
encountered in glider winching.
Why is it that for years winches have been developed and used in the UK
and Europe with no real problems and all of a sudden someone *comes up
with probably the most moronic suggestion ever and that is that if the
tension on the cable is increased the winch slows down to compensate.
So I leave the ground and the glider starts to rotate to the climb,
increasing the tension on the cable so it slows down. Brilliant, it takes
a real towering intellect to think that one through. I suppose the
explanation will be that there is some clever electronic gizzmo to
compensate. The problem with high technology systems is they do not tend
to be robust and they require regular maintainace to ensure their correct
operation, (MVG Winch is a perfect example, most of the advanced features
don't work) whereas a well trained winch driver can do the necessary
compensation using good old fashioned judgement far more safely.
I would far rather place my trust in a basic winch with a well trained
driver that rely on dubious untried engineering solutions driven by the
unknowing.
Skylaunch, Tost, Supercat and MVG winches perform very well with very few
problems. Skylaunch, or Skylaunch re-engined winches are probably now the
most popular winch in use in the UK. We like them and the many years of
experience that has gone into them.

PS We do not have deserts in the UK, and we don't cancel comps just
because 2 or 3 people don't get away either.

Don, you have so utterly misunderstood the concept, it's difficult to
start a reply.

A tension controlled winch maintains tension, the pilot controls
speed. He does that in exactly the same way as in free flight - nose
up to slow, nose down to speed up. No matter what he does, the
tension remains at the same high percentage of the weak link
strength. The pilot cannot change the tension, only the speed. The
tension cannot exceed the weak link strength.

It's exactly like an airplane. Rope tension is the equivalent of
thrust. The winch provides the power and the pilot flies the glider.
The beauty is that no mater the turbulence wind layers or thermals,
airspeed remains under the pilots total control.

With an airplane on takeoff, even a powerful one, if you raise the
nose, the airspeed will decrease. If you lower the nose, the airspeed
will increase. It's how it works - hundreds of thousands of times a
day. A tension controlled winch does exactly the same thing.
Airplane pilots understand the concept instantly.

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 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