All techie stuff here
Finsterwalder uses a 110 g/m2 Dacron called Aircloth. It is lighter even than UVODL04 that is 135 g/m2 (I am not saying anything about stretching).
Instead to use the usual impregnation of the fabric to get dimensional stability it uses a fine webbing to reach the same shear stability. Other brands (e.g. North Sails) has the same sailcloth construction but in much heavier versions (not suitable for hang gliders).
Why Finsterwalder is the only one that uses this kind of sailcloth. It could save two or three lbs per sail (I am thinking about P3 and bottom surface of Sport 2, probably it is too flexible for a U2).
A question for people that have Fex wings: is Aircloth durable as the standard Dacron as the Finsterwalder advertisement says?
I think there is a good reason why Wills Wing does not use it. One of its main R&D focus is about sailcloth.
There are other newer alternatives: Pro Lite from Dimension Polyant (same supplier of Wills wing) that is almost lighter as Aircloth but uses Dynema (U-PE) in its construction or Fibercon Competition from Contender (that one I have no glue about it construction).
UVODL04 is a great and sexy improvement of weight, performance and looking for competition gliders (T2C). However for designs that cannot get any performance improvement using the low stretching characteristics of UVODL04 (e.g. Falcon and Sport 2) a good light weight Dacron alternatives could be welcomed. Save two or three lbs in a state of the art aluminum frame as used by Wills Wing means substitute aluminum tubes by expensive carbon fiber. For people that has some back injury as me and my father, two or three lbs mean a quicker restart in the sport.
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By DAVE 858
I have heard it is known to catch on fire at higher airspeeds.

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