The line lenght mistery

[remko 0]

Part of packing is inspecting the canopy. Since it gets jerked at a lot doing CReW I leave it out after the last jump of the weekend. This has two advantages. First it enables me to drink beer sooner, secondly I take some extra time during the week to give it an extra look. I check for little burn holes in the fabric and mark them so I can differentiate the new ones from the old ones. I check for loose stitches, dents/loose/sharp edges on slider/container grommets, corrosion on quick links (especially under the lines) and the lines... It's easy to spot a damaged line, but I am also interested in checking the length. I want to know how much my canopy is out of trim and how much is much or too much.
This is where the mistery starts. I understand that, for a lightning anyway, the lines of a canopy is like paint for a car. You can order all kinds of lengths and trims. The subject is more complicated than I first thought due to the cascades (assuming for simplicity that ALL lines are cascaded). Is it true that all A-lines should be equally long? In other words that the canopy shape is circular, left to right, when the connector links are held together? And that the difference in A/B/C/D/Steering lines is linear? In other words that the under side, front to aft, of the canopy is straight? And how much difference is acceptable, 1 inch, 2, 3? I heard someone say that A lines are in principle cut as a multitude of feet, true? But lines shrink A LOT as a result of produced heat by for example slider movement. How much is "a lot"? 1 foot, 2?
Remko
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Skydive long and prosperous.

[PhreeZone 15]

Line/ Tirm shrinkage is usally less then 3 inches on a way our of trim canopy. The outer lines shrink more and faster then the inter lines shrink.
Call or Email PD or your canopy maker for a Trim chart. They will give you the ideal length for each line to see how far off you are.
Cause I don't wanna come back down from this cloud... ~ Bush

[riggerrob 558]

The previous poster was correct.
By the time your lines have shrunk or stretched by 3 inches from factory trim, you are due for a new line kit.
If you tell me which size of Lightning you have, I will post the trim numbers here.
I only have one Lightning trim chart. I am assuming that it is the stock trim. For the more exotic competition trims, you will have to contact the Performance Designs factory.

[Hooknswoop 19]

The smaller the canopy, the larger the effect 3 inches out of trim would make to the performance. A manta 288 that is 3 inches out of trim won't be affected nearly as much as a crossfire 89 that is 3 inches out of trim. That is why the small canopys usually have vectran lines. It would be nice if manufactures would recommend a maximum tolerance for each size canopy. Maybe a percentage across the board for each type of canopy.
Hook