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#41
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SAFE Winch Launching
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 |
#42
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SAFE Winch Launching
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 |
#43
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SAFE Winch Launching
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. |
#44
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SAFE Winch Launching
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. |
#45
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SAFE Winch Launching
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. |
#46
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SAFE Winch Launching
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. |
#47
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SAFE Winch Launching
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. |
#48
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SAFE Winch Launching
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 |
#49
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SAFE Winch Launching
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 |
#50
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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. |
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