Interview with Best kite designer Peter Stiewe
Peter, what can you tell me about the 06 Yarga-Pro, the name is familiar but the kite looks very different?
The name will be familiar, as will be the feel of the kite to everybody who rode the Yarga, but itÃ¢â‚¬â„¢s a new design from the ground up. Every aspect of the kite has been revised in one way or another, from chord length to aspect ratio, construction methods down to material choices throughout the kite, itÃ¢â‚¬â„¢s all change. The only thing that really remains is the fact that it can still be flown four line or five line just like last years kites.
We knew from the Hellfish that Cuben cloth worked in a kite and gave some unique performance advantages. We also learnt that it needed strict adherence to different construction techniques compared to normal materials to get the best out of the new cloth.
So thatÃ¢â‚¬â„¢s why we have the Yarga-Pro, itÃ¢â‚¬â„¢s a high performance Dacron/Cuben kite that sits above the classic Yarga in the range, and is the result of our considerable labours with Cuben. ItÃ¢â‚¬â„¢s also the first kite in what will be called the Pro-line range.
Why was Cuben chosen, what are the advantages of this cloth against others ?
If I had to sum it up, I would say two things, stiffness and bias load transfer.
Kites turn due to the differential loads put through the wingtips, so using Cuben in the wingtips, with its zero stretch properties, means these loads are transferred more efficiently to the airframe of the kite. So just adding Cuben to the wingtip panels helps to improve the turning response of the kite.
With Cuben in the leading edge we can make a kite very stiff where the airframe inputs to support the foil shape for efficiency. This helps hold more accurate foiling in the canopy which allows us to develop slightly more power from the same canopy area. CubenÃ¢â‚¬â„¢s stiffness and bias transfer properties are key to this improvement.
At the same time using Cuben for the majority of the leading edge allows us to make the leading edge thinner, whilst still retaining the stiffness of larger leading edges, but without the weight penalty. Also a thinner leading edge reduces the drag on the kite, which improves the speed across the window and also improves depower by increasing the potential upwind angle.
When you add these together in one kite you get a significant improvement in performance and usability.
Has using Cuben made the kites much lighter?
The amount of reinforcement used to make the Pro-line bombproof means that weight savings are minimized. ItÃ¢â‚¬â„¢s a justifiable trade off when you factor in that using Cuben allows us to reduce the leading edge size and make the kites usable over an increased wind range compared to other c-shaped kites.
How has using Cuben altered the construction of the kite?
Nearly the whole construction of the kite is changed from previous Best kites, each feature has been extensively tested and logged, some of the prototypes have over 300 hours flying time logged on them.
The Pro-line of kites all have a circular leading edge; this gives a stronger leading edge with no bias loads being transferred across weak joints. Most failures in segmented leading edges happen around the circumferential seam, as loads from one tube section are transferred as shear into the next section, across the joint. Everyone has seen this type of leading failure at some point or other on segmented leading edge designs.
The load distribution in a circular leading edge is more homogenous, when you add this together with CubenÃ¢â‚¬â„¢s ability to transfer bias loads, you get a more durable and stiffer leading edge.
Why is only part of the kite made from Cuben and why only the wingtips and centre of the leading edge?
Best are all about providing the best performing kite for the money, thatÃ¢â‚¬â„¢s what people expect and want from us. As an example, having a Cuben canopy helps transfer loads a little better, as do the Cuben wingtips, but the cost of a fully Cuben canopy is prohibitive for most riders, so we put the features into production that have the best performance return.
In the leading edge, thereÃ¢â‚¬â„¢s little bias load operating towards the wingtip section, so Cuben was overkill, we tried all the theoretical variations, and in the end the best solution closely matched what we had predicted from our experience with previous models. ItÃ¢â‚¬â„¢s pleasing when you know you have finally got something dialled in correctly.
And thatÃ¢â‚¬â„¢s why the Yarga-Pro is constructed the way it is, we put the Cuben in the places that give the greatest performance gains.
What lessons were learned from the Hellfish development, how did that affect the way that Cuben was used?
There was a lot to learn from the project to develop the first kite made from an all new material, the number one thing we learnt from the Hellfish was that small but important details could get lost in translation between the R&D facility and production in China.
Every test weÃ¢â‚¬â„¢ve made on Cuben is now part of the kite data file, including all the knowledge from the Pro-line series R&D. We have a huge data resource on everything to do with using Cuben that we didnÃ¢â‚¬â„¢t have previously. It covers everything from the different needles we use for different materials, the 3 different weights and compositions of thread, reinforcement materials we use across the kite, right down to the stitch hole spacing and variety of specific bonding we use to provide the strongest and most durable seams in the leading edge.
As well as the physical things about the design of the kites, thereÃ¢â‚¬â„¢s also the process involved in getting the kite into production exactly as we designed it in the R&D facility. We now go to china for every feature change, everything from R&D is overseen in china every step of the way.
ItÃ¢â‚¬â„¢s been a much longer process, but IÃ¢â‚¬â„¢m confident itÃ¢â‚¬â„¢s the best way of doing it.
How long was the development cycle?
ItÃ¢â‚¬â„¢s hard to put a start date down as you always develop on your previous knowledge base, everything that was learned with the development of the Hellfish shows up somewhere in the Yarga Pro & Nemesis Pro and a whole lot more.
At BestÃ¢â‚¬â„¢s new R&D facility in Brazil everything is logged and recorded so we know exactly how many hours every kite has logged on it. And with wind every day around 20knots you can imagine how many hours each test kite gets, revisions have up to 300 hours on them before we are satisfied now.
How does the Yarga-Pro Rider experience differ from the basic Yarga?
The new Yarga-Pro points upwind with less drag, like a smaller kite, due to the reduced leading edge size. The new Ã¢â‚¬Ëœfull-circleÃ¢â‚¬â„¢ strut connections have allowed us to improve the accuracy of the foiling in the canopy, which gives a more efficient kite, add this to the reduced leading edge diameter and you have a kite that penetrates further into the window for better depower and improved range. At the same time this greater accuracy in the canopy gives you improved pull when not driven right to the edge of the window and operating at lower angles of attack.
The kites also turns faster and tighter, it has quicker reaction to bar pressure, with direct feedback, overall it has a more responsive feel, similar to flying on shorter lines, but without feeling nervous. The feel will be familiar to all Yarga riders, it is immediately a better Yarga. It manages to feel like a smaller and more reactive kite at the top end.
Because our team riders have all chosen to ride our latest designs (Yarga Pro & Nemesis Pro) in competition, as opposed to sticking with the more familiar older models, we feel sure weÃ¢â‚¬â„¢ve got the mix just right.
Has the Pro-line range development given anything back to the classic rip stop and Dacron kites in the best line up?
All the 06 kites benefit from having new strut to leading edge connections, this Ã¢â‚¬Ëœfull-circleÃ¢â‚¬â„¢ joint, stiffens the air frame and allows the use of reduced sized struts. Shrinking the struts has allowed us to clean up the air-flow under the kite, and this adds to the efficiency of all the kites in the range. It also helps improve relaunch by allowing faster water run off and making the kite even easier to flip. As well as the circular LE for better load distribution and durability.
Moving the R&D facility to Brazil as part of the Pro-line development has also meant that we are able to get out and test kites almost every single day, and with riders dropping in everyday to ride the lagoons, we have no shortage of willing and skilled test pilots.
If anyone is in the area, they should call in and take a Yarga-Pro for a spin.
Who is this kite aimed at?
ItÃ¢â‚¬â„¢s for anyone who wants a better kite. If you can stay upwind, youÃ¢â‚¬â„¢re good enough to ride a Yarga pro. ItÃ¢â‚¬â„¢s for improving kite riders who know how to fly and are looking to handle a performance kite, for riders wanting that performance edge without giving up the familiar c-shape feel and security.
ItÃ¢â‚¬â„¢s a solid kite with a really smooth feel, just as happy being de-powered and cruised around on all day as it is, being thrashed around in the waves.
With a lot of attention being given to the newer style of Ã¢â‚¬Ëœhigh projected areaÃ¢â‚¬â„¢ kites, how do you think a high performance c-shape like the Yarga-pro fits into the market?
Not everyone wants to listen to the same music, some like country music, some like classical, but the Best guys like to roc
hope you guys like the info.