If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#21
|
|||
|
|||
SAFE Winch Launching
To Alan Larson.
I tried to reply to your questions directly, but your spam filter doesn't seem to like my tiscali email address. So the answers a 1) How high you get depends on the length of the run, the power of the winch (ours are Skylaunches with plenty of power and good control) and the headwind component. 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. 2) A wingtip touching the ground during an aerotow ground run is not normally an issue for aerotowing, provided that it's on a smooth surface or very short grass. Having said that I once did £5.5k's worth of damage to my glider trying to aerotow out of a cowfield with rather clumpy grass, when I caught a wingtip in a particularly lush clump before I could get the wing up and groundlooped violently. With a winch launch, because you are putting in a lot of energy very quickly, a cartwheel can develop very quickly; hence the need to abort the launch if a wing drops. You also have to fly the glider in such a way that you can always recover from a launch failure, which basically involves a short initial safety climb and controlling the rate of rotation. If you pull up like a Saturn rocket taking off, you are in severe danger or either flick spinning on the cable, or stalling heavily into the ground if the cable breaks or the winch fails early on! 3) It's surprising how often you find a thermal straight off the top of a winch launch. I suppose this is because the heat generated by the winch engine triggers off a thermal. Otherwise you head off to the nearest cumulus cloud, or look for birds or other gliders circling. It is considered polite to move out of the way before the next glider is ready to launch and not to circle low down in the base leg area, but that often allows 5 minutes or so in which to climb, by which time you may be high enough not to conflict. 4) When training new members we normally start them off with aerotows to get them used to being in the air and to learn how to control the glider before transferring to the winch. Having said that, many UK clubs do all their training by winch. 5) For obvious reasons you have to have a system in place that prevents aerotows and other aircraft from taking off at the same time as a winch launch is taking place. We have an appointed 'launch point controller' whose job it is to coordinate all movements by radio. We also place the winch launch point about 500 yards in from the downwind boundary and on a grass area away from the main runway, so most gliders, tugs and light aircraft can land short of there without conflicting with the cables. Unfortunately this costs us some potential launch launch height. If we use the full length of the airfield (1900yards) we can get 2500ft winch launches even in nil wind. We sometimes do this when things are quiet, but then you have to stop launching whenever there is an aircraft or glider on approach. Also the higher you take the cables, the more likely they are to drift over something expensive after a cable break. Regards, Derek Copeland At 13:30 09 July 2009, Del C wrote: Pros and Cons of winch launching: PROS: 1) A new professionally built winch will probably cost less than a new towing aircraft. If you build your own from scrap automobile/truck parts it will cost considerably less. 2) A winch doesn't require a highly qualified and certificated driver, Certificates of Airworthiness, 50 hour checks, etc, etc. Some routine maintenance is required though. 3) Low carbon footprint. A winch launch consumes less than a fifth of the fuel required for an aerotow 4) No aircraft noise complaints. 5) Given proper training and pilot awareness, it's pretty safe. 6) Winch launching is cheap; at our club less than a third of the cost of a 2000ft aerotow, even with professional winch drivers. So ideal for training and circuit bashing. A decent soaring pilot can usually get away from the sort of heights achieved, in the right conditions. 7) You don't have to learn accurate formation flying behind a tug. 8) You are unlikely to kill the winch operator, as opposed to a tug pilot who can be killed if you get too high or too out of position. 9) Above all IT'S FUN. CONS: 1) Launch height is limited by by the length of the cable run and the headwind component. On a still day you will at best get about 45% of the cable run. Launching directly into a headwind will improve this. 2) You can't get towed to a source of lift, such as a cumulus cloud or a ridge. You always end up right over the winch. 3) Pilots need to be fairly well trained and switched on to deal with launch failures and cable breaks. 4) Winch Cables may conflict with power flying at a mixed operation site. Derek Copeland |
#22
|
|||
|
|||
SAFE Winch Launching
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? |
#23
|
|||
|
|||
SAFE Winch Launching
On Jul 11, 9:36*am, 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? That you, Lennie? -T8 |
#24
|
|||
|
|||
SAFE Winch Launching
Unlike Bill Daniels, I tell it as it is without exaggerations and unproven
assumptions. The figures I gave are for a K13, which winch launches less well than a K21 because the belly hook is too far forward. K21's get about 200 feet higher, especially when flown solo.Also Bill Daniel's winch is using synthetic Dyneema cable which adds about 150 feet to the launch compared with the 4.5mm stranded steel cable we use. Dynema cable is superb stuff, but unfortunately 5 times more expensive than steel. As cable replacement is one of the major costs in winch launching, this makes it less economic. The Skylaunch winch gives well controlled, correctly speeded launches for every type of glider from slow old vintage single seaters up to big heavy two-seat DG1000 turbos. It is also very easy to drive (I am a winch driver). The gear change all occur during the ground run and are totally smooth and imperceptible from the glider end. If you build a winch with an automatic gearbox, you have to disable the kick down function and tweak the box so that it changes up at fairly low revs. I agree with Bill that you can't just stick an unmodified automatic gearbox into a winch without encountering the sort of problems that seem to beset Gerhlein winches. It is also important to get the overall gearing correct. For a good quality Skylaunch launch of a K21 to 2300ft into about a 5 knot headwind see: http://www.youtube.com/watch?v=4ArI5_1PE_Y BTW. My reply was genuine in response to an email from a gent called Alan Larson. I tried twice to reply by email, but got delivery failure notifications with the text: The following message to email address was undeliverable. The reason for the problem: 5.1.0 - Unknown address error 550-'5.0.0 All tiscali sends is spam' OK Tiscali is not the best ISP in the world for keeping out spam, but even so.....? I have removed Alan's actual email address to prevent him getting any spam. Derek Copeland At 13:36 11 July 2009, bildan wrote: On Jul 11, 2:00=A0am, 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? |
#25
|
|||
|
|||
SAFE Winch Launching
In article
, 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? My club used to have a very good winch. It was a one-off called the "Eagle Winch" and was designed and built by one of our members. He got his initial glider training in Germany and had knowledge of quality winches. That winch is now with the Philadelphia Glider Council, I believe. We were forced to let go of it because we moved to a municipal airport that was incompatible with winch operations (crossing runways). The Eagle winch has an automatic transmission. However, in our operation it was locked into 2nd gear for normal conditions. In strong wind, we used 1st gear. No gear changes necessary. It was very easy to operate and became even more so after the steel cable was swapped our for plasma rope by the second owners at the Memphis club. At our original field, with 4000 feet of cable out, we could easily launch our single seaters to 2000 feet if we had any headwind. |
#26
|
|||
|
|||
SAFE Winch Launching
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 |
#27
|
|||
|
|||
SAFE Winch Launching
On Jul 11, 9:15*am, Derek Copeland wrote:
Unlike Bill Daniels, I tell it as it is without exaggerations and unproven assumptions. The figures I gave are for a K13, which winch launches less well than a K21 because the belly hook is too far forward. K21's get about 200 feet higher, especially when flown solo.Also Bill Daniel's winch is using synthetic Dyneema cable which adds about 150 feet to the launch compared with the 4.5mm stranded steel cable we use. Dynema cable is superb stuff, but unfortunately 5 times more expensive than steel. As cable replacement is one of the major costs in winch launching, this makes it less economic. The Skylaunch winch gives well controlled, correctly speeded launches for every type of glider from slow old vintage single seaters up to big heavy two-seat DG1000 turbos. It is also very easy to drive (I am a winch driver). The gear change all occur during the ground run and are totally smooth and imperceptible from the glider end. If you build a winch with an automatic gearbox, you have to disable the kick down function and tweak the box so that it changes up at fairly low revs. I agree with Bill that you can't just stick an unmodified automatic gearbox into a winch without encountering the sort of problems that seem to beset Gerhlein winches. It is also important to get the overall gearing correct. For a good quality Skylaunch launch of a K21 to 2300ft into about a 5 knot headwind see: http://www.youtube.com/watch?v=4ArI5_1PE_Y BTW. My reply was genuine in response to an email from a gent called Alan Larson. I tried twice to reply by email, but got delivery failure notifications with the text: The following message to email address was undeliverable. The reason for the problem: 5.1.0 - Unknown address error 550-'5.0.0 All tiscali sends is spam' OK Tiscali is not the best ISP in the world for keeping out spam, but even so.....? I have removed Alan's actual email address to prevent him getting any spam. Derek Copeland At 13:36 11 July 2009, bildan wrote: On Jul 11, 2:00=A0am, 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? The Hydrowinch is currently fitted with Spectra 12-strand, not Dyneema nor Plasma-12. Having now driven some number of launches and having trained another to drive the Hydrowinch, I'd say it has some very nice features. There are a some others that I've suggested to the developers. There've been a couple of set backs, one of which led to a three month delay. These folks have day jobs also and since some of the team comes from overseas, it does slow things a bit. I'd like to put it on line today, but that's not my decision to take. They aren't so compromising, but it's close. Frank Whiteley |
#28
|
|||
|
|||
SAFE Winch Launching
Our club uses a mid seventies Tost winch with a Skylaunch throttle system
and a second hand 454 cid chevvy big block and standard truck autobox, running 4.5mm stranded wire. The engine was imported second hand from USA three years ago It seems to be a mid seventies perhaps early eighties truck motor with associated gearbox, sourced from a scrapyard and fitted with a few mods but NO alterations save to disable kickdown and to run with lpg we did not look inside the engine and it used less than 5 litres of oil in 3000 launches. It is very smooth partly due to all the rollers and associated bearings being renewed. As John noted the gearchanges on this standard autobox are imperceptible and completed by approx 10' AGL . Driving is much the same as before but less variable owing to the throttle guide system. The old engine was a 425 cid oldsmobile engine with stock autobox which was finally retired spewing oil and rattling but still launching. The biggest differences arose with the new rollers and LPG both make these big winches much smoother. Simple cheap and very effective Jon Dorset Gliding Club, UK |
#29
|
|||
|
|||
SAFE Winch Launching
At 19:34 11 July 2009, johngalloway wrote:
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 some 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 Totally agree with all of that. I believe the Hydrostart winch on which the Hydrowinch is based costs an astonishing 500,000 Euros, so it ought to be damn good! Makes a Skylaunch 2 at 90,000 Euros sound very good value, and it is a tried and tested design. And remember that they do a cut down and simplified version called the Skylaunch 3 for a lot less than that, if you can do without air conditioned cabs etc. Until recently we had a demo Skylaunch with a GM 502 High Torque engine. On that you could open the throttle up to the preset as fast as the gas strut would allow you to. However we have just bought two new winches with the High Power engine and I initially got some complaints about banging the tails of K13s down a bit hard at the start of the ground run, so I have slowed down opening the throttle to about 3 seconds, as you suggest. You also have to start backing off the throttle for the last third of the launch to avoid overspeeding the glider. As long as you know that you have to do this it is not difficult. What the Skylaunch does brilliantly in my opinion, is to give a very consistent ground run and rotation, whatever type of glider you are flying. With our old Tost winches you could get anything from a dangerously fast snatch into the air to a slow and ponderous ground run with a risk of a wing drop. If a launch starts right it tends to stay right, so we get consistently higher launches from them, if only for that reason. Derek Copeland |
#30
|
|||
|
|||
SAFE Winch Launching
On Jul 11, 11:45*am, Berry wrote:
In article , *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? My club used to have a very good winch. It was a one-off called the "Eagle Winch" and was designed and built by one of our members. He got his initial glider training in Germany and had knowledge of quality winches. That winch is now with the Philadelphia Glider Council, I believe. We were forced to let go of it because we moved to a municipal airport that was incompatible with winch operations (crossing runways). The Eagle winch has an automatic transmission. However, in our operation it was locked into 2nd gear for normal conditions. In strong wind, we used 1st gear. No gear changes necessary. It was very easy to operate and became even more so after the steel cable was swapped our for plasma rope by the second owners at the Memphis club. At our original field, with 4000 feet of cable out, we could easily launch our single seaters to 2000 feet if we had any headwind. Germany is a good place to learn about winches. Plasma rope is like night and day compared to steel. Steel cable is evil stuff. If you have a winch actually designed for Plasma - unlike the Skylaunch and Gerhlein - it will outlast steel by as much as 5x making it actually cheaper in the long run. Did you actually lock your transmission in 2nd or just place the gear selector in 2nd? It's an important question since a standard tranny will still make the 1-2 upshift causing a power oscillation. We see a lot of tension traces showing tension oscillations from these winches. Anyone considering an automatic transmission for a gilder winch really needs to understand how they work. Automatics are highly developed for road vehicles whose requirements are diametrically opposed to those of a glider winch. If a road vehicle encounters an increasing load, such as a hill, it is designed to help the driver maintain speed by increasing torque to the wheels to meet the higher load, doing what it can to reduce the loss of speed. Cresting the hill and starting down, it reduces torque and tends toward coasting. Both actions increase vehicle performance and minimize fuel consumption. 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. |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Winch Launching in US | john hawkins | Soaring | 11 | June 10th 09 12:18 PM |
Winch Launching | Rolf | Soaring | 27 | January 7th 09 02:48 AM |
Ka8b winch launching | Jimmie L. Coulthard | Soaring | 11 | September 9th 08 08:38 AM |
Aerotow Fuel Costs & Winch Launching | Derek Copeland[_2_] | Soaring | 2 | May 26th 08 03:14 PM |
LIppmann reports a 950 meter winch launch with their Dynatec winch line - anything higher? | Bill Daniels | Soaring | 20 | December 27th 04 12:33 AM |