PistolPete

Since 26 Apr 2010
18 Posts
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Sat Jan 02, 16 12:21 am |
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Matt V wrote: | ...If you stretch a lightly loaded bridal line, it may shrink over the day back and throw the length off. Anybody know why this is? Is it long term elastic stretch? Dirt accumulation in the lines? Garden gnomes?
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Flysurfer wrote: | ...Aging means shrinking – Or: the properties of a line over time
If you have ever compared the lines of an older kite, then you have most likely noticed that the frontlines have lengthened over time in comparison to the backlines. If you took the time to measure, you would notice that it is actually the back lines which have shortened, whereas the front lines have hardly changed at all. Confusing, at first, but enlightening if you take a closer look.
You have to have it in the back of your head that the lines are extremely pre-stretched and cured before delivery. Bending the lines (e.g. while winding) or abrasion (e.g. after rotations), the coating of a line fractures. In addition, sand or dust can get into the lines over time. Both have an effect: the line gets thicker and therefore, shorter. This is almost and sometimes entirely reversed by the frontlines, by the high load that must be carried while kiting. Still, while the back lines are subject to only a little load, they shorten remarkably, sometimes up to 20 centimeters. Under normal use, the lines should be readjusted after one year, earlier under frequent use.
http://www.flysurfer.com/en/news/4774-kiteleinen-eine-wissenschaft-fur-sich/
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Several years ago I remade cabrinha crossbow bridle lines with amsteel 7/64", copying the same lengths that were on the kite, worked fine. I also have remade spare part lines on flysurfer speeds using amsteel (made it adjustable by adding knots, so I would not have to keep replacing lines), again worked fine. Qpower line is easy (can tie knots with) to replace non-pulley bridle lines, once again had worked fine on old kites I had rebuilt. Instead of Qpower for flying lines, I prefer making Jerry Brown 800# center lines and 500# steering lines. Use amsteel again to make long pigtails and add knots if I need to shorten a line to get equal length flying lines. |
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