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#41
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Ask arround the sailing community about how much one can be hurt by a
flailing synthetic rope - it might not be as bad as wire in some ways but because it is infinately more flexible it can be just as bad. "Bob Johnson" wrote in message ... Hi Bill -- After my limited experience with it, I can't help but think that synthetic is going to be a lot safer and less nasty to work with during breaks or whenever else it has to be dodged or handled. It's light as a feather, soft as a baby's butt and stores absolutely no energy. BJ "W.J. (Bill) Dean (U.K.)." wrote: A winch should never have any doors or windows open while actually launching. The cab must be fully enclosed, doors and windows shut. The windows must be of laminated glass or similar, with Lexan or something similar on the inside surfaces. Any openings not glazed must be protected with expanded metal sheet, weldmesh or similar. If the cable breaks, and sooner or later it will, it can get inside the winch through any opening with amazing ferocity. One of the Long Mynd amateur winch drivers had the back window slightly open. The cable broke, came in through the window and attacked his clothing. He considered he had a very lucky escape, and has given up driving the winch. At another club one of the most experienced of all winch drivers parked his car directly behind the winch and facing it, what he thought was a safe distance away. This was at a busy club which has done many thousands of winch launches every year for a very long time. The cable broke and flew back, trashing the back of his car and round the car to break one of the front door windows. I saw the car afterwards and asked who had run into him. This sort of thing does not happen very often so it takes people by surprise. It is a completely avoidable risk and is just not worth taking. W.J. (Bill) Dean (U.K.). Remove "ic" to reply. "Martin Gregorie" wrote in message ... snip Climate control: there is a diesel burning heater for winter and the sliding doors open in summer. Martin Gregorie |
#42
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Stephen is right - IF you get tangled in it while it is under tension,
Spectra cut right through you like any strong line. Since you need a strong line, there's no getting away from that. The real danger from winch line is ballistic impact and there steel is far more dangerous. The commercial shipping and barge industries have almost completely switched from wire rope to Spectra on the safety issue alone. Steel stretches,storing energy like a spring - that energy is released in a springback when it breaks. Steel cable used to result in a hundred or so deck hand deaths a year. Spectra has eliminated those deaths. Spectra creeps under load and creeps back a little when it breaks - no real danger there. Spectra does not eliminate the danger posed by line termination hardware like carabiners and weak links. Those can hit the winch cab with the energy of a pistol bullet. A good strong, armored cab is still a necessity. (A heater and air conditioner would be nice too.) Bob is right in that Spectra is sweet to work with. Bare hands are fine - no gloves needed to protect your hands from "fish hooks" that are common with stranded steel cable. It's not black and white, but steel is far more dangerous than spectra and that alone makes it worth the switch. Bill Daniels "Stephen Haley" wrote in message ... Ask arround the sailing community about how much one can be hurt by a flailing synthetic rope - it might not be as bad as wire in some ways but because it is infinately more flexible it can be just as bad. "Bob Johnson" wrote in message ... Hi Bill -- After my limited experience with it, I can't help but think that synthetic is going to be a lot safer and less nasty to work with during breaks or whenever else it has to be dodged or handled. It's light as a feather, soft as a baby's butt and stores absolutely no energy. BJ |
#43
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Martin -
I appreciate that, Bert. So far all the bad break descriptions have described the cable lashing straight back over the winch. Has anybody known it to go sideways and if so, how far to the side? I'm now wondering if I should park the cable truck further away still or if my usual position is reasonable. As Bert said, the cable may strike anything within its range. That means to the side as well as straight back. Where the cable goes in a break depends little upon the wind (it has a low drag profile), but primarily on the failure mode of the cable. The rupture across a cable is not simultaneous at all points. It proceeds (rapidly) from one side to the opposite, and in doing so may impart a large lateral force on the cable. I have seen cable breaks, not in sailplane launching, where the cable whipped its full length to the side. The whole circle of radius equal to the length of the cable out, must be avoided if unprotected. Ed Grens |
#44
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"E. A. Grens" wrote in message ... Martin - I appreciate that, Bert. So far all the bad break descriptions have described the cable lashing straight back over the winch. Has anybody known it to go sideways and if so, how far to the side? I'm now wondering if I should park the cable truck further away still or if my usual position is reasonable. As Bert said, the cable may strike anything within its range. That means to the side as well as straight back. Where the cable goes in a break depends little upon the wind (it has a low drag profile), but primarily on the failure mode of the cable. The rupture across a cable is not simultaneous at all points. It proceeds (rapidly) from one side to the opposite, and in doing so may impart a large lateral force on the cable. I have seen cable breaks, not in sailplane launching, where the cable whipped its full length to the side. The whole circle of radius equal to the length of the cable out, must be avoided if unprotected. Ed Grens This was also briefed to me at Aston Down on the reverse pulley, that the wire clearance zone was quite large in the event of a break it could flail about a large radius around the pulley. Frank Whiteley |
#45
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On Thu, 06 Nov 2003 03:12:58 GMT, "E. A. Grens"
wrote: Martin - I appreciate that, Bert. So far all the bad break descriptions have described the cable lashing straight back over the winch. Has anybody known it to go sideways and if so, how far to the side? I'm now wondering if I should park the cable truck further away still or if my usual position is reasonable. As Bert said, the cable may strike anything within its range. That means to the side as well as straight back. Where the cable goes in a break depends little upon the wind (it has a low drag profile), but primarily on the failure mode of the cable. The rupture across a cable is not simultaneous at all points. It proceeds (rapidly) from one side to the opposite, and in doing so may impart a large lateral force on the cable. I have seen cable breaks, not in sailplane launching, where the cable whipped its full length to the side. The whole circle of radius equal to the length of the cable out, must be avoided if unprotected. Ed Grens Thanks, all. Noted for future reference. -- martin@ : Martin Gregorie gregorie : Harlow, UK demon : co : Zappa fan & glider pilot uk : |
#46
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Bill Daniels wrote:
... It's not black and white, but steel is far more dangerous than spectra and that alone makes it worth the switch. ... A lot of other factors are to be considered when deciding to switch. In our case, as we just spent a lot of money in 6 reels of 1km of new steel cables, which is already a questionable decision when you consider the very low use of the winch, spending a much higher lot of money in spectra is even more questionable. |
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