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#1
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Plasma Ropes ----- Help
To any club using plasma ropes in place of steel.
Having read the benefits of this type of rope, several UK clubs are interested in its use. One major obstacle to this, is cutting it during a launch, in the event of an emergency So far the best methods appear to be an axe an anvil type cutter. Any slight imperfections on scissor, guillotine and even the axe methods of cutting mean the rope does not get completely cut through. Even though the equipment cuts steel succesfully. Various methods such as hot wire and laser beams have been suggested, but with the way members treat club equipment I suspect the life of such things would be minimal. What emergency cutting methods for plasma rope do those who use it employ? Thanks in anticipation Dave Martin |
#2
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I understand that Skylaunch have developed a guillotine that cuts it very
nicely. |
#3
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"Dave Martin" wrote in message ... Various methods such as hot wire and laser beams have been suggested, but with the way members treat club equipment I suspect the life of such things would be minimal. Dave Martin Why should a hot blade be fragile? The winch engine starting battery has a lot of power to heat a robust blade very quickly. You only need to get the blade to Spectra's 265F melting point - far below the blades melting point. I would just mount the blade in a strong frame near the path of the rope and push the rope against the stationary hot blade with a rubber block. If well built, it should last nearly forever. Bill Daniels |
#4
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Surely a scissor type gulliotine would be more effective
Ian "Dave Martin" wrote in message ... To any club using plasma ropes in place of steel. Having read the benefits of this type of rope, several UK clubs are interested in its use. One major obstacle to this, is cutting it during a launch, in the event of an emergency So far the best methods appear to be an axe an anvil type cutter. Any slight imperfections on scissor, guillotine and even the axe methods of cutting mean the rope does not get completely cut through. Even though the equipment cuts steel succesfully. Various methods such as hot wire and laser beams have been suggested, but with the way members treat club equipment I suspect the life of such things would be minimal. What emergency cutting methods for plasma rope do those who use it employ? Thanks in anticipation Dave Martin |
#5
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Tried that, with a shiny new freshly sharpened scissor type guillotine, and it
didn't cut it, this stuff has very fine fibres which just bent around the corners. even using heat-shrink sleeving to simulate a plastic coating, we got the same results, you simply could not be sure of cutting the rope. |
#6
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Dave --
Just thinking out loud here, always dangerous: nail guns, either percussive, powered with shotgun shell or the like, or pneumatic with air cylinder. Sorry, no blueprints available. Replace nail with blade would be good. Wondering about guillotines in general, I know it's always good to have one, but has anyone in earshot actually used one? If so, what were the circumstances, line running or still, weak link or no, spring, gravity or muscle powered, radios or how did you know and like that. Bob Johnson Dave Martin wrote: To any club using plasma ropes in place of steel. Having read the benefits of this type of rope, several UK clubs are interested in its use. One major obstacle to this, is cutting it during a launch, in the event of an emergency So far the best methods appear to be an axe an anvil type cutter. Any slight imperfections on scissor, guillotine and even the axe methods of cutting mean the rope does not get completely cut through. Even though the equipment cuts steel succesfully. Various methods such as hot wire and laser beams have been suggested, but with the way members treat club equipment I suspect the life of such things would be minimal. What emergency cutting methods for plasma rope do those who use it employ? Thanks in anticipation Dave Martin |
#7
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How about a chunk of "Det. cord" in a circle or two with the Plasma rope
running through the center. Use a "pull" type of initiator to trigger the Det. cord. Bill Higdon Bill Daniels wrote: Bob, you need to get some of this stuff and play with it. It doesn't cut the way metal does - in fact, it's the preferred body armor for knives and penetrating weapons. The people who work with this stuff all the time use electrically heated hot blades. They cut through it like it isn't even there. Bill Daniels "Bob Kuykendall" wrote in message om... Earlier, "Bill Daniels" wrote: Why should a hot blade be fragile? The winch engine starting battery has a lot of power to heat a robust blade very quickly. I would definitely look askance at a system that required electricity to cut the cable, and I think that most certification authorities might also. I prefer my emergency systems to be powered by gravity, strong springs, or if necessary percussion-lit pyrotechnics. You only need to get the blade to Spectra's 265F melting point - far below the blades melting point. I'd tend to believe that you need to heat the blade to about twice or three times that - to account for the fact that you might be trying to cut the cable as it is running in or out, and so the blade is transferring heat to a pretty large volume of cable. Also, you'd want to cut the cable as fast as possible. This might be a neat idea if it were heated by exhaust from the winch engine... My preference would be for a sharp guillotine, for which the blade can pivot slightly to account for minor misalignments between the arm axis and the plane of the anvil. I'd try an anvil made of a 2" by 6" piece of MDF (medium density fiberboard) to be renewed after each slice. In testing, I'd look for 25 cuts out of 25 tries. Just my few ill-formed thoughts on the matter. Thanks, and best regards to all Bob K. |
#8
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There was a fatal accident in the U.K. when the glider being launched got
the launching wire over a wing. The guillotine was fired by the winch driver, but failed to cut the wire (which was of course being pulled out by the glider). It is not certain that cutting the wire would have saved the pilot, but he had little chance with it uncut. As a consequence of this accident we are very aware in the U.K. of the necessity for a reliable method of cutting the cable. The guillotine was re-designed, and they are now regularly serviced and tested in accordance with a laid-down schedule. So the answers to your question are; yes, the winch driver could see the problem, the guillotine failed to cut the wire. W.J. (Bill) Dean (U.K.). Remove "ic" to reply. "Bob Johnson" wrote in message ... snip Wondering about guillotines in general, I know it's always good to have one, but has anyone in earshot actually used one? If so, what were the circumstances, line running or still, weak link or no, spring, gravity or muscle powered, radios or how did you know and like that. Bob Johnson |
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