The guys at Duotone caught up with designer Ralf Grösel about the two and a half year development process that advanced the Juice D/LAB to the absolute top end of what’s possible in the industry right now. Packed with future technology, Ralf explains the challenges that had to be overcome in the production process with the new material Aluula and how Duotone succeeded in creating unreal new kiting possibilities in hardly any wind at all — get a taste of the sensational feeling of kiting in 4-5 knots! The Juice D/LAB sets a totally new benchmark in light wind performance and it’s pretty obvious why Ralf considers this gamechanger as “the most interesting kite I’ve created in my entire career.”
Welcome Ralf, great to talk to you today, could you tell us where this kite sits in the Duotone range and what people can expect from the new Juice D/LAB?
It’s a pleasure for me to talk about the Juice D/LAB, a kite I’ve been working on for two and half years now. Juice D/LAB stands for Duotone Laboratory. This is a division of Duotone where we are creating kites which are the absolute top end of what is possible in the industry right now and the Juice D/LAB is sort of a revolution and definitely the most interesting kite I’ve done in my career, it’s amazing!
Tell us about the materials that have made the Juice D/LAB possible.
The Juice D/LAB features the Aluula material, which is currently the lightest material available on the market, it’s 80 gsm, for example, Penta TX on our SLS series is 130 gsm so it’s quite a big difference. With the Juice being the industry standard in its class, the Juice D/LAB is the cherry on the cake when it comes to ultimate light wind performance. I have changed quite a few variables to make it work, on the technical design and then also on the production side. That is one of the reasons it took us so long to get this kite ready as we had to change various production and sowing techniques to make the product come to fruition in a way we were satisfied with.
We’ve seen Aluula come out in other brands kites, but there definitely have also been some issues with the material, how difficult was it to overcome these difficulties?
It was the biggest, it’s not material as we are used to dealing with, it’s closer to a laminate construction and these laminates are extremely vulnerable to point loads such as needle holes. So to make it work we have done various tests of different seam constructions at the Lab we have in Germany. We had to establish a new sowing line at our factory in Sri Lanka to make it happen. It took many prototypes to validate it. This was more related to the structural stability and long term durability than adjustments to the flight characteristics. The original Juice was already a very good base for me to progress so the challenge was definitely to make the material work the way we would like to see it work.
Could you tell us how the material properties differ from Aluula to Penta TX to Dacron?
If you take the Juice it comes with a 140gsm Dacron on the leading edge. Aluula is not a normal woven material, it’s a laminate with two foils and some woven yarn in-between, it has a completely different character in every single regard. When you take a kite design from the computer model and simply change the material, it doesn’t work as it will deform in a totally different way, for example when you inflate the kite the material will elongate in different areas, so you’re receiving a different kite. It’s still the same construction, but you’re receiving a different kite. For example, the overall weight is different, the way the tips are controlled.
When the leading edge is different, that automatically affects the trailing edge so you end up designing a new kite, but you know exactly what you are looking for. It’s not as if you are starting from zero, you have to find a way to consider the previous design to make something that comes close to what you know to give you the right starting point and then from there work your way to the ultimate goal, which is always the handling characteristics. On a light-wind kite, this is the key aspect, that when you send the kite down (in the wind window) that the up stoke delivers as much power as possible, as this keeps your momentum on the water. If you have lightweight material, you don’t need so much energy for the upstroke performance which allows more room for tuning to the handling which is where we focused.