SAFE Winch Launching

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

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

I mis typed, ..
the winch is relevant to a good launch, but the pilot is responsible for
the safety,


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

If Skylaunches winches are supposed (by Bill Daniels) to be so bad, how
come I got 55knots on the nail (perfect speed) for every winch launch I
did on a Skylaunch today while instructing in a K13 in quite windy, rough
and gusty conditions? No oscillations, no over or underspeeds, no weak
link breaks and no unwanted gear changes.

Derek Copeland


At 21:45 12 July 2009, David Chapman wrote:
I mis typed, ..
the winch is relevant to a good launch, but the pilot is responsible for
the safety,


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

On Jul 12, 4:30*pm, Del C wrote:
If Skylaunches winches are supposed (by Bill Daniels) to be so bad, how
come I got 55knots on the nail (perfect speed) *for every winch launch I
did on a Skylaunch today while instructing in a K13 in quite windy, rough
and gusty conditions? No oscillations, no over or underspeeds, no weak
link breaks and no unwanted gear changes.

Derek Copeland

At 21:45 12 July 2009, David Chapman wrote:



I mis typed, *.. *
the winch is relevant to a good launch, but the pilot is responsible for
the safety,

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

Because you operate at low throttle settings and you have no clue what
turbulent air is. Try flying in the desert sometime.

On Jul 12, 3:30*pm, 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?


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.

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.

On Jul 13, 6:30*am, Del C wrote:
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.

In fact, with an automatic transmission in the drive line, it's
impossible to ever get the rope tension exactly right - certainly not
with something as simple minded as a throttle stop.

Most of what an automatic actually does in a glider winch is either
unnecessary or detrimental. Only the auto-clutch action at idle is
useful and there are far better ways to do that. The only
justification for using an automatic in a winch is that it's cheap and
comes with the engine.

The idea that low starting gears are necessary with a glider winch is
absurd. Tost gutted their automatics - even while saying automatics
were dangerous - to eliminate everything but the torque converter
leaving the box in it's straight through 1:1 ratio. Simple torque
calculations show that 3rd gear is capable of breaking the strongest
weak link during acceleration. Stepping through 1st and 2nd gears
only makes it more difficult to achieve accurate acceleration.

When our Tost winches were fitted with 'one speed' (fixed in top)
automatic gearboxes, the ground run acceleration for the heavier two
seater was somewhat ponderous, although they could still rocket launch
lightweight K8 single seaters. They also tended to overheat the gearbox
oil, despite being fitted with big oil coolers with electric fans.

This was also why you had to apply full throttle to get the gliders moving
and then back off as the gliders entered the full climb, to avoid a huge
overspeed. From a winch driver's point of view, it was hard to get this
right, which was probably the cause of some of the awful launches we used
to have to endure in that era.

Derek Copeland


At 14:49 13 July 2009, bildan wrote:
On Jul 13, 6:30=A0am, Del C wrote:
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
Skylaunc=
h
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
th=
e
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=3DA0pm, David Chapman
wrote:

But other nonsense posted here . please help me, =3DA0...

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. =A0Stock 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. =A0The 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. =A0As the vehicle encounters a load such as a hill,
the
torque output actually increases as the RPM is pulled down by the
increasing load. =A0The 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.

In fact, with an automatic transmission in the drive line, it's
impossible to ever get the rope tension exactly right - certainly not
with something as simple minded as a throttle stop.

Most of what an automatic actually does in a glider winch is either
unnecessary or detrimental. Only the auto-clutch action at idle is
useful and there are far better ways to do that. The only
justification for using an automatic in a winch is that it's cheap and
comes with the engine.

The idea that low starting gears are necessary with a glider winch is
absurd. Tost gutted their automatics - even while saying automatics
were dangerous - to eliminate everything but the torque converter
leaving the box in it's straight through 1:1 ratio. Simple torque
calculations show that 3rd gear is capable of breaking the strongest
weak link during acceleration. Stepping through 1st and 2nd gears
only makes it more difficult to achieve accurate acceleration.