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

Kar loči naša padala od konkurence je dejstvo, da smo pripravljeni vnesti v krilo mešanico materialov, s katerimi za vsako potrebno lastnost uporabimo točno določen material. Verjamemo, da je to bistvenega pomena, v kolikor hočemo trgu ponuditi proizvod z zadnjo preverjeno tehnologijo.

Preden obrazložimo kako uporabljamo vrvice na naših padalih je prav, da se najprej seznanimo s tem, kar je danes aktualno na trgu:

Dyneema: Trenutno defenitivno daleč najmočnejši material zaenkrat na trgu, kar za tretjino močnejši od ostalih aramidnih/kevlarskih vrvic z enakim diametrom. To pa tudi še ni vse: Dyneema prav tako tudi zelo dobro prenaša test upogibanja vrvice. Ta material zdrži skoraj 5000 ciklov, brez da bi sama vrvica poslabšala svoje lastnosti. Hkrati pa je Dyneema tudi bolj vzdržljiva pri UV lastnostih, tudi neoplaščena vrvica bo imela veliko daljšo življenjsko dobo od ostalih kevlarskih vrvic. Vseeno pa ima tudi slabšo lastnost, to je krčenje takrat, kadar vrvica ni pod napetostjo. To se malenkostno poveča še pri višjih temperaturah, kjer se Dyneema še prej skrči.

Aramidne/kevlarske vrvice: Te klasične vrvice so v uporabi v padalstvu že mnogo let. Kevlarju niso všeč testi upogibanja, saj se pri nekaj 1000 ciklih hitro pokažejo slabše lastnosti materiala. Novi pristopi namakanja vrvic v posebne premaze so pomagali pri UV vzdržljivosti, vsi pa vemo, da tudi ti premazi počasi popustijo in tako postane kevlar kar naenkrat izpostavljen velikemu stresu.
Ta material se ne krči kadar ni pod napetostjo, se pa podaljša kadar je izpostavljen napetosti dalj časa.

Na naših zadnjih modelih, od Knighta dalje, smo dobre in slabe lastnosti teh materialov uporabili v prid boljše postavitve vrvic, katera zagotavlja, da je življenjska doba dolžine vrvic kar se da najdaljša.
Nove PPSL Liros Dyneema vrvice so tako postavljene na A in B gurtni, kjer vrvice doživljajo največjo napetost. Dyneema je tam pod napetostjo in tako ostaja v svoji dolžini. Hkrati je ta Dyneema tudi oplaščena, kar pripomore k vidljivosti vrvic na štartu. Na C gurtni pa smo tako postavili kevlarske vrvice, ki imajo boljšo stabilnost pri manjših napetostih. Vrvice na C-jih so večinoma pod zelo majhno napetostjo, tako da se v tej situaciji ne raztegujejo, ampak ostanejo dalj časa v svojih merah. S tem smo lastnosti obeh materialov optimizirali za dolgo življenjsko dobo, z minimalnim trimanjem padala skozi življenjsko dobo krila.

Triple Seven – nič ni naključno

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