Duotone NOW Magazine No.03 2022

94 D R I V I N G F U T U R E I N N O V A T I O N S KENWINNER: It’s a challenge to understand fully all the kite-related implications of a material’s properties. Understanding durability is a big challenge, so we do bench testing of seam strength using different seam constructions, adhesives and threads. We do stretch testing on warp, fill and bias. We repeat stretch tests after cloth is fluttered for a period of time. We test tear strength both before and after hard use and we test kites at kite schools where they get a lot of hard use in harsh climates. Understanding stretch and shrinkage is a challenge. When we went from our standard Dacron to the Penta TX in our SLS kites, we had to adjust for the lower warp and fill stretch of the Penta TX. This was a satisfying adjustment to make because less stretch in the leading makes it easier for us to create a really smooth entry shape to the front of the canopy. WHICH SPECIAL CHARACTERISTICS OF A KITE DO YOU SPECIFICALLY INFLUENCE / CONTROL WITH THE USE OFWHICH NEWMATERIALS? KENWINNER: We’ve been mostly concerned lately with weight reduction, which influences drift, power, depower and turning quickness. Both our SLS (Penta TX) and D/LAB (Aluula) kites are better in these respects. We’ve also gained better turning performance and strut durability with our Flex Strut construction, for which we use a lighter but more robust polyester material. We gained better canopy durability by going to a new ripstop (replacing heavier Dacron) in the trailing edges of the canopies. Duotone Kite designers Ken Winner (Rebel, Neo, Mono) and Ralf Grösel (Juice, Evo, Dice, Vegas) as well as Antonio Destino, Head of R&D and Product Management of Duotone comment on questions of the science of fabrics. WHAT IS THE BIGGEST CHALLENGE WHEN WORKING WITH NEW CLOTH MATERIALS? Photo  Toby Bromwich Photo  Lukas K. Stiller INWHICHOF YOUR KITE LINES / INWHICH SIZES DO LIGHTWEIGHTMATERIALS MAKE THEMOST SENSE? RALF GRÖSEL: Lightweight materials and the resulting lightweight kites have two product advantages: they work well in less wind. This is perfectly logical: if something is light, I need less wind to do the lifting work. The upstroke of the kite is supported when a kite is particularly light. The drift behavior is significantly improved. So light materials make sense for large kites, conceivably for the Juice, for large sizes of the Evo, or even for a Rebel. In drift, the Neo of course, where drift is the main focus. KENWINNER: Any kite that will experience marginal power – that is, any kite that will at some point be under-powered during a session – can benefit a lot from low weight. Any light- wind kite (particularly large Juice and Neo models), any kite that has to drift to maintain flying line tension (wave kites like Neo), and any kite that is used with a hydrofoil (all sizes of Neo, Juice and Evo) will be more fun to ride. Lower weight helps with power on the upstroke, drift and quickness to turn. However, this difference in stretch also affected the curve of the leading edge of SLS kites – the curve of the leading edge as viewed from both the side and the front – a fact that we did not immediately appreciate fully. Once we realized what was going on we were able to focus more intently on some of the more subtle aspects of kite shape. And we were ultimately rewarded with overall better kite performance. Understanding stiffness and how it affects performance is also a challenge. When we worked on our D/ LAB kites, which are currently using Aluula in the leading edge and some struts, we immediately appreciated the benefits of lower weight, but we didn’t immediately appreciate the challenges we would face in several areas. 95 D R I V I N G F U T U R E I N N O V A T I O N S S C I E N C E O F F A B R I C S