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#1
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Winching: Steel vs. Plasma
Further to Craig Freeman's post of July 28, photos of our new winch are
available at our club web site at http://www.permiansoaring.us/ The winch was conceived and built by Craig in about three months of spare time work, which is surely remarkable. Even more remarkable, Craig also wears additional hats as both club president and CFIG. A short winch description includes a freshly shopped 454 cu.-in. engine turning a 48-inch by 6-inch drum at about 8.5/1 reduction. As near as I can learn, the stock 454 engine generates about 325 hp and 350 lb-ft of torque at 3500 rpm. In June, we started our new winch operations using 3/16-in. stranded steel cable. With 5000-ft. of line out, we were averaging about 1200 ft. of launch height with our 1100-lb. Blanik, using the CG bridle. Craig wanted to evaluate Plasma rope, so we re-equipped in July. Since then, our launch heights have been running 1500-ft. or better. All of our towing so far has been in light winds of 10-15 kt. Since spooling on the Plasma, we have also enjoyed zero line-handling hassle, as covered by Craig and Bill Daniels in their recent ras posts. The physics of the two types of launch cable together with winch operation are kind of interesting. With steel, we were launching our Blanik in about four seconds to a speed of 50 kt., at which point climb was initiated and maintained at about 55 kt. Horizontal acceleration for the period was about 0.7 G. Total power draw from the engine was calculated at about 135 hp. With Plasma, the acceleration period was reduced to about three seconds to reach the same airspeed. Required engine power was reduced slightly, and acceleration was increased to about 0.9 G. During climb to release, which takes about 45 seconds on average, I'm estimating engine power required is reduced to about 110 hp for both steel and Plasma, including aerodynamic drag of the glider and towline. In my calculations, the force accelerating the glider at momentary full throttle was estimated at 1000-lb. I backed into this figure by observing the regular acceleration-phase line breaks we were initially experiencing using certified 1000-lb. poly rope for the weak link. Since switching to Plasma and 1320-lb. Tost weak links, any line breaks are occurring in the release area of the launch, where they are supposed to take place. As Bill Daniels has previously mentioned, it might be interesting to learn just how much force the glider is actually seeing during acceleration and climb. Bob Johnson |
#2
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explain PLASMA mate,
I always thought plasma would be the liquid part of blood or highly ionised gas is it kind of a rope? nylon? kevlar? latex :-) ? diameter? how to repair? ..... Chris "Bob Johnson" wrote in message ... Further to Craig Freeman's post of July 28, photos of our new winch are available at our club web site at http://www.permiansoaring.us/ The winch was conceived and built by Craig in about three months of spare time work, which is surely remarkable. Even more remarkable, Craig also wears additional hats as both club president and CFIG. A short winch description includes a freshly shopped 454 cu.-in. engine turning a 48-inch by 6-inch drum at about 8.5/1 reduction. As near as I can learn, the stock 454 engine generates about 325 hp and 350 lb-ft of torque at 3500 rpm. In June, we started our new winch operations using 3/16-in. stranded steel cable. With 5000-ft. of line out, we were averaging about 1200 ft. of launch height with our 1100-lb. Blanik, using the CG bridle. Craig wanted to evaluate Plasma rope, so we re-equipped in July. Since then, our launch heights have been running 1500-ft. or better. All of our towing so far has been in light winds of 10-15 kt. Since spooling on the Plasma, we have also enjoyed zero line-handling hassle, as covered by Craig and Bill Daniels in their recent ras posts. The physics of the two types of launch cable together with winch operation are kind of interesting. With steel, we were launching our Blanik in about four seconds to a speed of 50 kt., at which point climb was initiated and maintained at about 55 kt. Horizontal acceleration for the period was about 0.7 G. Total power draw from the engine was calculated at about 135 hp. With Plasma, the acceleration period was reduced to about three seconds to reach the same airspeed. Required engine power was reduced slightly, and acceleration was increased to about 0.9 G. During climb to release, which takes about 45 seconds on average, I'm estimating engine power required is reduced to about 110 hp for both steel and Plasma, including aerodynamic drag of the glider and towline. In my calculations, the force accelerating the glider at momentary full throttle was estimated at 1000-lb. I backed into this figure by observing the regular acceleration-phase line breaks we were initially experiencing using certified 1000-lb. poly rope for the weak link. Since switching to Plasma and 1320-lb. Tost weak links, any line breaks are occurring in the release area of the launch, where they are supposed to take place. As Bill Daniels has previously mentioned, it might be interesting to learn just how much force the glider is actually seeing during acceleration and climb. Bob Johnson |
#3
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Let me take this since Bob Johnson and I have been talking about his for a
long time. "Plasma" is a US marketing name for Ultra High Molecular Weight Poly Ethylene (UHMWPE). It is sold elsewhere as "Dyneema". (The use of the word "Spectra" makes it hard for search engines to find the stuff.) Spectra has a specific gravity of about .97 so it is very light. (it floats) It is available as 12-strand braided cord in a range of diameters. 5mm diameter seems a good choice for winch launching gliders since it has a breaking strength of about 5500 pounds. For lighter single-seat gliders, 3mm might work very well. Since it is very strong, light, and has no tendency whatever to tangle it seems the perfect winch line. There are two drawbacks. The large one is cost which is three to four times as much as steel but Plasma promises to last much longer than steel. (The price seems to be coming down fast) The other is a low melting point of about 287F with strength starting to diminish above 150F. Both these can be managed by operational changes. Splicing is very easy. Just a tuck splice like water ski rope works fine. Bill Daniels "CH" wrote in message ... explain PLASMA mate, I always thought plasma would be the liquid part of blood or highly ionised gas is it kind of a rope? nylon? kevlar? latex :-) ? diameter? how to repair? .... Chris "Bob Johnson" wrote in message ... Further to Craig Freeman's post of July 28, photos of our new winch are available at our club web site at http://www.permiansoaring.us/ The winch was conceived and built by Craig in about three months of spare time work, which is surely remarkable. Even more remarkable, Craig also wears additional hats as both club president and CFIG. A short winch description includes a freshly shopped 454 cu.-in. engine turning a 48-inch by 6-inch drum at about 8.5/1 reduction. As near as I can learn, the stock 454 engine generates about 325 hp and 350 lb-ft of torque at 3500 rpm. In June, we started our new winch operations using 3/16-in. stranded steel cable. With 5000-ft. of line out, we were averaging about 1200 ft. of launch height with our 1100-lb. Blanik, using the CG bridle. Craig wanted to evaluate Plasma rope, so we re-equipped in July. Since then, our launch heights have been running 1500-ft. or better. All of our towing so far has been in light winds of 10-15 kt. Since spooling on the Plasma, we have also enjoyed zero line-handling hassle, as covered by Craig and Bill Daniels in their recent ras posts. The physics of the two types of launch cable together with winch operation are kind of interesting. With steel, we were launching our Blanik in about four seconds to a speed of 50 kt., at which point climb was initiated and maintained at about 55 kt. Horizontal acceleration for the period was about 0.7 G. Total power draw from the engine was calculated at about 135 hp. With Plasma, the acceleration period was reduced to about three seconds to reach the same airspeed. Required engine power was reduced slightly, and acceleration was increased to about 0.9 G. During climb to release, which takes about 45 seconds on average, I'm estimating engine power required is reduced to about 110 hp for both steel and Plasma, including aerodynamic drag of the glider and towline. In my calculations, the force accelerating the glider at momentary full throttle was estimated at 1000-lb. I backed into this figure by observing the regular acceleration-phase line breaks we were initially experiencing using certified 1000-lb. poly rope for the weak link. Since switching to Plasma and 1320-lb. Tost weak links, any line breaks are occurring in the release area of the launch, where they are supposed to take place. As Bill Daniels has previously mentioned, it might be interesting to learn just how much force the glider is actually seeing during acceleration and climb. Bob Johnson |
#4
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I saw at your web page, that you winch from a concrete runway.
Doing so with steel cables reduced the lifetime by a factor 10 compared to launching on gras. How is the abrasive behaviour of this cable? Do you have a the manufacturers address? Chris Hostettler Melbourne Australia "Bill Daniels" wrote in message ... Let me take this since Bob Johnson and I have been talking about his for a long time. "Plasma" is a US marketing name for Ultra High Molecular Weight Poly Ethylene (UHMWPE). It is sold elsewhere as "Dyneema". (The use of the word "Spectra" makes it hard for search engines to find the stuff.) Spectra has a specific gravity of about .97 so it is very light. (it floats) It is available as 12-strand braided cord in a range of diameters. 5mm diameter seems a good choice for winch launching gliders since it has a breaking strength of about 5500 pounds. For lighter single-seat gliders, 3mm might work very well. Since it is very strong, light, and has no tendency whatever to tangle it seems the perfect winch line. There are two drawbacks. The large one is cost which is three to four times as much as steel but Plasma promises to last much longer than steel. (The price seems to be coming down fast) The other is a low melting point of about 287F with strength starting to diminish above 150F. Both these can be managed by operational changes. Splicing is very easy. Just a tuck splice like water ski rope works fine. Bill Daniels "CH" wrote in message ... explain PLASMA mate, I always thought plasma would be the liquid part of blood or highly ionised gas is it kind of a rope? nylon? kevlar? latex :-) ? diameter? how to repair? .... Chris "Bob Johnson" wrote in message ... Further to Craig Freeman's post of July 28, photos of our new winch are available at our club web site at http://www.permiansoaring.us/ The winch was conceived and built by Craig in about three months of spare time work, which is surely remarkable. Even more remarkable, Craig also wears additional hats as both club president and CFIG. A short winch description includes a freshly shopped 454 cu.-in. engine turning a 48-inch by 6-inch drum at about 8.5/1 reduction. As near as I can learn, the stock 454 engine generates about 325 hp and 350 lb-ft of torque at 3500 rpm. In June, we started our new winch operations using 3/16-in. stranded steel cable. With 5000-ft. of line out, we were averaging about 1200 ft. of launch height with our 1100-lb. Blanik, using the CG bridle. Craig wanted to evaluate Plasma rope, so we re-equipped in July. Since then, our launch heights have been running 1500-ft. or better. All of our towing so far has been in light winds of 10-15 kt. Since spooling on the Plasma, we have also enjoyed zero line-handling hassle, as covered by Craig and Bill Daniels in their recent ras posts. The physics of the two types of launch cable together with winch operation are kind of interesting. With steel, we were launching our Blanik in about four seconds to a speed of 50 kt., at which point climb was initiated and maintained at about 55 kt. Horizontal acceleration for the period was about 0.7 G. Total power draw from the engine was calculated at about 135 hp. With Plasma, the acceleration period was reduced to about three seconds to reach the same airspeed. Required engine power was reduced slightly, and acceleration was increased to about 0.9 G. During climb to release, which takes about 45 seconds on average, I'm estimating engine power required is reduced to about 110 hp for both steel and Plasma, including aerodynamic drag of the glider and towline. In my calculations, the force accelerating the glider at momentary full throttle was estimated at 1000-lb. I backed into this figure by observing the regular acceleration-phase line breaks we were initially experiencing using certified 1000-lb. poly rope for the weak link. Since switching to Plasma and 1320-lb. Tost weak links, any line breaks are occurring in the release area of the launch, where they are supposed to take place. As Bill Daniels has previously mentioned, it might be interesting to learn just how much force the glider is actually seeing during acceleration and climb. Bob Johnson |
#5
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thanks
I am digging on the net found some interesting informations at http://www.dsm.com/en_US/html/hpf/ropes.htm http://www.thecortlandcompanies.com/...=1&categoryid= HMPE (Plasmaź, Spectraź, Dyneemaź) High modulus polyethylene fibers produced by gel-spinning ultra-high molecular weight polyethylene (UHWPE) Excellent strength-to-weight ratio Highest abrasion resistance of any fiber Excellent dynamic toughness Very low elongation (3% - 5%) Excellent flex fatigue resistance Low resistance to heat Susceptible to creep 5mm in Diameter 5400-ft 1800m 77-lb. 35kg but for getting a quote I would need the yarn technical name - something like SK50, Plasma...... Chris "Bob Johnson" wrote in message ... G'day, Chris and thanks, Bill -- Here's what the sticker on the shipping reel had written on it: Cortland Cable Co, Inc PO Box 330 Cortland, NY 13045 607 753 8276 Fax 607 753 3138 5400-ft 77-lb. (The reel weighed 11-lb.) Actually asphalt or tarmac, but you're correct about the wear. Invariably, the steel would quickly develop waves or slight bends, and these areas would receive the abrasion. Broken outer strands would soon poke out with ugly "wickers" and any sorting out would soon teach you to use gloves, which weren't always 100% effective. With Plasma, wickers and sorting out have both gone away. Given its cost we're devoutly hoping the Plasma has an exceptionally long life. BJ CH wrote: I saw at your web page, that you winch from a concrete runway. Doing so with steel cables reduced the lifetime by a factor 10 compared to launching on gras. How is the abrasive behaviour of this cable? Do you have a the manufacturers address? Chris Hostettler Melbourne Australia "Bill Daniels" wrote in message ... Let me take this since Bob Johnson and I have been talking about his for a long time. "Plasma" is a US marketing name for Ultra High Molecular Weight Poly Ethylene (UHMWPE). It is sold elsewhere as "Dyneema". (The use of the word "Spectra" makes it hard for search engines to find the stuff.) Spectra has a specific gravity of about .97 so it is very light. (it floats) It is available as 12-strand braided cord in a range of diameters. 5mm diameter seems a good choice for winch launching gliders since it has a breaking strength of about 5500 pounds. For lighter single-seat gliders, 3mm might work very well. Since it is very strong, light, and has no tendency whatever to tangle it seems the perfect winch line. There are two drawbacks. The large one is cost which is three to four times as much as steel but Plasma promises to last much longer than steel. (The price seems to be coming down fast) The other is a low melting point of about 287F with strength starting to diminish above 150F. Both these can be managed by operational changes. Splicing is very easy. Just a tuck splice like water ski rope works fine. Bill Daniels "CH" wrote in message ... explain PLASMA mate, I always thought plasma would be the liquid part of blood or highly ionised gas is it kind of a rope? nylon? kevlar? latex :-) ? diameter? how to repair? .... Chris "Bob Johnson" wrote in message ... Further to Craig Freeman's post of July 28, photos of our new winch are available at our club web site at http://www.permiansoaring.us/ The winch was conceived and built by Craig in about three months of spare time work, which is surely remarkable. Even more remarkable, Craig also wears additional hats as both club president and CFIG. A short winch description includes a freshly shopped 454 cu.-in. engine turning a 48-inch by 6-inch drum at about 8.5/1 reduction. As near as I can learn, the stock 454 engine generates about 325 hp and 350 lb-ft of torque at 3500 rpm. In June, we started our new winch operations using 3/16-in. stranded steel cable. With 5000-ft. of line out, we were averaging about 1200 ft. of launch height with our 1100-lb. Blanik, using the CG bridle. Craig wanted to evaluate Plasma rope, so we re-equipped in July. Since then, our launch heights have been running 1500-ft. or better. All of our towing so far has been in light winds of 10-15 kt. Since spooling on the Plasma, we have also enjoyed zero line-handling hassle, as covered by Craig and Bill Daniels in their recent ras posts. The physics of the two types of launch cable together with winch operation are kind of interesting. With steel, we were launching our Blanik in about four seconds to a speed of 50 kt., at which point climb was initiated and maintained at about 55 kt. Horizontal acceleration for the period was about 0.7 G. Total power draw from the engine was calculated at about 135 hp. With Plasma, the acceleration period was reduced to about three seconds to reach the same airspeed. Required engine power was reduced slightly, and acceleration was increased to about 0.9 G. During climb to release, which takes about 45 seconds on average, I'm estimating engine power required is reduced to about 110 hp for both steel and Plasma, including aerodynamic drag of the glider and towline. In my calculations, the force accelerating the glider at momentary full throttle was estimated at 1000-lb. I backed into this figure by observing the regular acceleration-phase line breaks we were initially experiencing using certified 1000-lb. poly rope for the weak link. Since switching to Plasma and 1320-lb. Tost weak links, any line breaks are occurring in the release area of the launch, where they are supposed to take place. As Bill Daniels has previously mentioned, it might be interesting to learn just how much force the glider is actually seeing during acceleration and climb. Bob Johnson |
#6
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I found that,
but shall I just ask that I need the same cable that your gliding club is using? There must be a name for the cable or is it just "Plasma 5mm" ??? CHo "Bob Johnson" wrote in message ... http://www.thecortlandcompanies.com/...asp?width=1031 CH wrote: thanks I am digging on the net found some interesting informations at http://www.dsm.com/en_US/html/hpf/ropes.htm http://www.thecortlandcompanies.com/...=1&categoryid= HMPE (Plasmaź, Spectraź, Dyneemaź) High modulus polyethylene fibers produced by gel-spinning ultra-high molecular weight polyethylene (UHWPE) Excellent strength-to-weight ratio Highest abrasion resistance of any fiber Excellent dynamic toughness Very low elongation (3% - 5%) Excellent flex fatigue resistance Low resistance to heat Susceptible to creep 5mm in Diameter 5400-ft 1800m 77-lb. 35kg but for getting a quote I would need the yarn technical name - something like SK50, Plasma...... Chris "Bob Johnson" wrote in message ... G'day, Chris and thanks, Bill -- Here's what the sticker on the shipping reel had written on it: Cortland Cable Co, Inc PO Box 330 Cortland, NY 13045 607 753 8276 Fax 607 753 3138 5400-ft 77-lb. (The reel weighed 11-lb.) Actually asphalt or tarmac, but you're correct about the wear. Invariably, the steel would quickly develop waves or slight bends, and these areas would receive the abrasion. Broken outer strands would soon poke out with ugly "wickers" and any sorting out would soon teach you to use gloves, which weren't always 100% effective. With Plasma, wickers and sorting out have both gone away. Given its cost we're devoutly hoping the Plasma has an exceptionally long life. BJ CH wrote: I saw at your web page, that you winch from a concrete runway. Doing so with steel cables reduced the lifetime by a factor 10 compared to launching on gras. How is the abrasive behaviour of this cable? Do you have a the manufacturers address? Chris Hostettler Melbourne Australia "Bill Daniels" wrote in message ... Let me take this since Bob Johnson and I have been talking about his for a long time. "Plasma" is a US marketing name for Ultra High Molecular Weight Poly Ethylene (UHMWPE). It is sold elsewhere as "Dyneema". (The use of the word "Spectra" makes it hard for search engines to find the stuff.) Spectra has a specific gravity of about .97 so it is very light. (it floats) It is available as 12-strand braided cord in a range of diameters. 5mm diameter seems a good choice for winch launching gliders since it has a breaking strength of about 5500 pounds. For lighter single-seat gliders, 3mm might work very well. Since it is very strong, light, and has no tendency whatever to tangle it seems the perfect winch line. There are two drawbacks. The large one is cost which is three to four times as much as steel but Plasma promises to last much longer than steel. (The price seems to be coming down fast) The other is a low melting point of about 287F with strength starting to diminish above 150F. Both these can be managed by operational changes. Splicing is very easy. Just a tuck splice like water ski rope works fine. Bill Daniels "CH" wrote in message ... explain PLASMA mate, I always thought plasma would be the liquid part of blood or highly ionised gas is it kind of a rope? nylon? kevlar? latex :-) ? diameter? how to repair? .... Chris "Bob Johnson" wrote in message ... Further to Craig Freeman's post of July 28, photos of our new winch are available at our club web site at http://www.permiansoaring.us/ The winch was conceived and built by Craig in about three months of spare time work, which is surely remarkable. Even more remarkable, Craig also wears additional hats as both club president and CFIG. A short winch description includes a freshly shopped 454 cu.-in. engine turning a 48-inch by 6-inch drum at about 8.5/1 reduction. As near as I can learn, the stock 454 engine generates about 325 hp and 350 lb-ft of torque at 3500 rpm. In June, we started our new winch operations using 3/16-in. stranded steel cable. With 5000-ft. of line out, we were averaging about 1200 ft. of launch height with our 1100-lb. Blanik, using the CG bridle. Craig wanted to evaluate Plasma rope, so we re-equipped in July. Since then, our launch heights have been running 1500-ft. or better. All of our towing so far has been in light winds of 10-15 kt. Since spooling on the Plasma, we have also enjoyed zero line-handling hassle, as covered by Craig and Bill Daniels in their recent ras posts. The physics of the two types of launch cable together with winch operation are kind of interesting. With steel, we were launching our Blanik in about four seconds to a speed of 50 kt., at which point climb was initiated and maintained at about 55 kt. Horizontal acceleration for the period was about 0.7 G. Total power draw from the engine was calculated at about 135 hp. With Plasma, the acceleration period was reduced to about three seconds to reach the same airspeed. Required engine power was reduced slightly, and acceleration was increased to about 0.9 G. During climb to release, which takes about 45 seconds on average, I'm estimating engine power required is reduced to about 110 hp for both steel and Plasma, including aerodynamic drag of the glider and towline. In my calculations, the force accelerating the glider at momentary full throttle was estimated at 1000-lb. I backed into this figure by observing the regular acceleration-phase line breaks we were initially experiencing using certified 1000-lb. poly rope for the weak link. Since switching to Plasma and 1320-lb. Tost weak links, any line breaks are occurring in the release area of the launch, where they are supposed to take place. As Bill Daniels has previously mentioned, it might be interesting to learn just how much force the glider is actually seeing during acceleration and climb. Bob Johnson |
#7
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Do any changes have to be made to the pay-on rollers, to avoid the
lighter rope slipping and potentially overheating locally? On our winch, the rollers are heavily scored where generations of steel cable have slipped a bit and cut into the surface. These rollers are now about 40 years old, maybe older. While they could perhaps be renewed with a good surface, they do have considerable inertia, and a free-running cable suddenly coming into contact with one of them is bound to take some time to whirl it up to speed. Steel stands up to that - would Spectra/Dyneema? Chris N. |
#8
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Following this thread with interest and I have spoken
to the UK importers. Some experimental work has been done in the UK. One identified problem is that the standard winch guillotines do not cut the plasma cable as efficiently as they do steel cable and that a strand or strands remain. Can any user comment on this please. Dave Martin At 09:24 12 August 2003, Chris Nicholas wrote: Do any changes have to be made to the pay-on rollers, to avoid the lighter rope slipping and potentially overheating locally? On our winch, the rollers are heavily scored where generations of steel cable have slipped a bit and cut into the surface. These rollers are now about 40 years old, maybe older. While they could perhaps be renewed with a good surface, they do have considerable inertia, and a free-running cable suddenly coming into contact with one of them is bound to take some time to whirl it up to speed. Steel stands up to that - would Spectra/Dyneema? Chris N. |
#9
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"Chris Nicholas" wrote in message ... Do any changes have to be made to the pay-on rollers, to avoid the lighter rope slipping and potentially overheating locally? On our winch, the rollers are heavily scored where generations of steel cable have slipped a bit and cut into the surface. These rollers are now about 40 years old, maybe older. While they could perhaps be renewed with a good surface, they do have considerable inertia, and a free-running cable suddenly coming into contact with one of them is bound to take some time to whirl it up to speed. Steel stands up to that - would Spectra/Dyneema? Chris N. Yes, I would think you should make some changes. Swiveling pulleys with smooth surfaces where the Spectra rope contacts the metal should extend the life of the rope considerably. Bill Daniels |
#10
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"Dave Martin" wrote in message ... Following this thread with interest and I have spoken to the UK importers. Some experimental work has been done in the UK. One identified problem is that the standard winch guillotines do not cut the plasma cable as efficiently as they do steel cable and that a strand or strands remain. UHMWPE rope is very resistant to cuts - which is a good thing except when you want the guillotine to cut it fast. Spectra is used in body armor that protects against cutting weapons. Taking advantage of the low melting point with a hot-blade guillotine seems the way to go. Just make a steel blade and mount it solidly next to the rope path. Use a rubber block to push the rope into the hot blade. Heat the blade with current from the starting battery. A direct shunt across the battery should heat the blade to 500C in a second or two. Bill Daniels |
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