Line material optimization
One of the things that sets our wings apart from most other paraglider manufacturer’s products is the way we employ different line materials down the chord of our gliders. We feel that this is a logical and necessary way to get the best out of the available technology, and minimise potential problems caused by the very low number of lines on modern wings.
Brief line material summary
Before we push on with how we use the different lines in our wings, here’s a brief summary of the materials available, with their strengths and weaknesses listed:
Dyneema: This is by far the strongest material available today; up to about 1/3 stronger that comparable Aramide/Kevlar lines in the diameters we use for paragliding. And that’s not all; Dyneema sustains bending far better than the other materials, showing little or no weakening after the usual “5000-cycle” bending tests used to sort wheat from chaff in the line manufacturing business. It bears mentioning that Dyneema is just about unsusceptible to UV damage, meaning sunlight doesn’t matter much even for an unsheathed Dyneema line. Unfortunately, Dyneema is somewhat more prone to shrinkage than other materials, especially when exposed to heat. Dyneema will generally return to the specified length again as soon as it is loaded up, but for lines under minimal load this may not happen.
Aramide/Kevlar: This is the “classic” paraglider line material, known for the light brown colour when not coloured. Kevlar doesn’t much like to go through bending-cycle tests, meaning it is significantly weakened by repeated bending, but new technologies for dyeing have almost completely removed the UV-exposure problem of old. Modern Aramide/Kevlar line is often dyed dark grey, as this is the most efficient dye for UV protection. The dyeing process also helps protect the surface of the line against physical abrasion.
Aramide/Kevlar line does not shrink, but may stretch a bit under heavy loads. Once stretched it will not return to its original length, but lines may be looped back into spec if this is necessary.
On recent Triple Seven wings, we use the strengths and weaknesses of these materials to our advantage, deploying the new PPSLS Liros Dyneema lines for the A’s and B’s, which are always under heavy loads and thus don’t shrink, and using High strength Magix Pro Aramid A8000 line, dyed in dark grey for UV protection, for the C lines. The C-lines are critical in keeping a paraglider within trim specs, and line shrink here leads to sluggish behaviour on launch and in the air, but with these Edelrid lines we eliminate that problem. At the same time the C-lines are not subjected to heavy loads, so if we make sure we dimension the lines appropriately from the beginning we can build gliders that will remain in spec for their life cycle.
Triple Seven – nothing is coincidental