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#51
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SAFE Winch Launching
At 14:52 12 July 2009, bildan wrote:
Do I have an emotional bias against crappy engineering? Damn right I do - especially when it's being sold as the 'perfect' solution. My club in New Jersey used to operate a winch. It was before my time (hard to believe anything was before my time, but there you are). It was made from a Model A Ford chassis. One rear axle was welded solid and a drum (probably made from an old truck wheel) was mounted on the other axle with the launch rope wrapped around it. They launched down the side of a hill and had one helluva lot of fun doing it. OK, this was back in the 1930s, as I've heard the tales. We'd all like to have the ultimate winch to launch with. We'd also like to all have Ferraris to drive. Most of us settle for what we can afford, and try to avoid letting the perfect become the enemy of the good. Jim Beckman |
#52
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SAFE Winch Launching
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. |
#53
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SAFE Winch Launching
On Jul 13, 2:45*am, Dave Martin wrote:
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 We are doing exactly that - and it's working! It's what has the Brits so agitated. |
#54
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SAFE Winch Launching
After reading these cat fights for well over a year, and now that it
has spilled out into RAS, I think this public (and personal) argument is doing harm to potential winch activity in the U.S. There are many glider pilots in the U.S. who believe that winch launching is more dangerous than aerotow… and this endless debate, about the merits of one technology over another, just fuels that skepticism. Engineers, by personality and training, want clear-cut black and white answers to a problem. The fact is that there is a lot of gray involved in what works with winch equipment. Regardless of the merits of new winch technology, Europe has been effectively winch launching for many decades with “traditional” mechanical technology. Setting the engineering skirmish aside, the old technology is proven to work over the course of hundreds of thousands of launches. Maybe the “new” technology is better, but keeping it in context – it is a potential alternative to the proven traditional technology, not *THE* definitive answer. This is what is being lost in this ongoing point and counter- point dialog. There are many of us who believe in the merits of winch launching; and that U.S. glider pilots would benefit from the widespread adoption of the technique. However, from a management standpoint these ongoing inscrutable arguments are a winch advocate’s public relations nightmare. The fact is that traditional automotive-based winch technology works, as proven by decades of successful use. The developing new technology may be an improvement, but that in no way negates the wide-spread use of lower cost existing technology. It would benefit the soaring community if the polarized principals in this personal disagreement would spend their time advocating winch launching as a method, rather than publically arguing over technical details that may or may not be relevant. For most of us involved in winching, the debate is somewhat amusing (if not distressing), but what is does do is to support anti-winch sentiment in the U.S. Just as we can effectively train new pilots in a K-13 or a DG-1000, we can effectively and safely winch launch with automotive-based hardware or new technology hardware. If we could re-focus this obsessive, bias, and argumentative dialog into promoting the use of ground launching it would be of greater benefit to the soaring community at large. Anyone agree? Bob Lacovara (Winch pilot, winch driver, winch advocate) |
#55
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SAFE Winch Launching
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. |
#56
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SAFE Winch Launching
After watching this thread deteriorate, it reminds me why I stopped participating in the WinchDesign Yahoo news group. The discussions became personal, agressive, angry, and absent of civility.
I really wish this thread would change its' tone, or move back to the WinchDesign group. .. |
#57
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SAFE Winch Launching
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. |
#58
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SAFE Winch Launching
Yeah... well, my point exactly. Over and out.
Bob Lacovara |
#59
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SAFE Winch Launching
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 Look, I didn't start this thread. You don't have a perfect winch and neither does anybody else. There's a LOT of room for improvements in every aspect of winch design. Keep an open mind. If you think that automatic gear changes don't matter, put a tension logger on yours for a few launches. The results will astonish you. What gets my dander up is "emotional" opposition to all attempts at innovation based on the idea that your domestic winch is 'perfect'. |
#60
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SAFE Winch Launching
At 15:01 13 July 2009, Wayne Paul wrote:
After watching this thread deteriorate, it reminds me why I stopped = participating in the WinchDesign Yahoo news group. The discussions = became personal, agressive, angry, and absent of civility. I really wish this thread would change its' tone, or move back to the = WinchDesign group. I started this thread off trying to promote winch launching as a safe, environmentally friendly and low cost means of launching gliders. Most gliding clubs in Germany, Holland, the UK and the Eastern European countries do the majority of their launches this way. The problem is Bill Daniels. I have no idea what his true agenda is: Maybe to build up a US winch building empire? However the BGA winching advisor, who knows everything there is to know about winch launching, has also given up posting on the Winch Design Group in disgust. Derek Copeland |
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