Ken Winner about the new "Juice"
What do you say when your mobile phone is out of battery? You say it's out of Juice. What do you say when your kite doesn't have enough power? Again, you're out of juice. We can't help you with the first problem, but for the second . . . we have Juice.
There are at least three main types of big kites:
-There are the big race kites, which are fast and have big wind range but aren't generally the best for handling or jumping. These kites need at least five struts and need to be light, so they have to be lightly built and are not the most bomb-proof kites around.
-Then there are the big airstyle kites, which have great wind range and jumping but are slow turning. These kites don't have to be particularly light because they are flown in plenty of wind, but this means they aren't the best at staying in the air in light wind.
- Finally, there are the big handling-oriented kites. These have to be light, durable and quick-turning. They're good for jumping and popping in light wind, but can also go big when powered. Unlike airstyle kites, they need to be nimble and quick. Unlike race kites, it's ok if they're not the last word in upwind performance.
This is where the Juice comes in. The Juice is based roughly on the Neo arc, strut count, profile and outline, but the aspect ratio has been stretched from 4.5 to 5.3, and the leading edge diameter has been shrunk a bit. The center strut is conventional -- so as to improve overall stability -- and the back pigtail is conventional because a relaunch bungee won't work well on such a thick LE tip.
Big kites have so much canopy area that they can really benefit from the stability provided by a lot of struts. Unfortunately, struts also add a lot of weight. We opted for three struts on the Juice because this number provides the best combination of low weight, high durability and good canopy stability.
You might wonder why not build a big kite with minimal weight by eliminating all struts, and this is certainly something we've considered. But our experience indicates that the lack of structure in strutless kites robs them not only of top end comfort and depower but also low end power. Add this to the tip flutter in turns and the strutless option seem limited.
The Neo has a floating strut in the center to give more complete luffing when sheeted out. We felt this was desirable on a smaller kite like the Neo. For the Juice, however, which is a much bigger kite, we felt a conventional strut in the center would give needed canopy stability.
The Juice shares the Neo arc. This arc gives a high segment count for good profile fidelity. It also provides smooth and quick steering while keeping good depower and sheet-go power delivery.
We know from testing a wide variety of kites that high aspect ratios can improve bar feel and depower in big kites by quite a bit. High AR can be overdone, as it can give an excessively long and heavy leading edge, but a moderate AR can be just right. With the Juice we found that an AR of 5.3 gave a nice short bar stroke without hurting other aspects of handling such as quick turning.
Given how well the Neo is working, we decided to stick with Neo profiles for the Juice.
We like to have several bridle anchor points on the leading edge so that bridle loads on the leading edge are well distributed. This led us to go with eight front bridle anchors.
We also like a bridle as short as possible, to reduce the chances of tangles and snags. The shortest bridles we tested did not give the best bar feel or turning ability so we lengthened the bridle to the point where steering and bar feel were good. This left the bridle still short enough that it can’t loop over the end of the leading edge.
Finally, we had to consider whether to go with a pseudo-pulley or fixed front pigtail. Since using a pulley would permit the Neo to work with a greater variety of safety systems, we decided to go with one pulley on each side of the front bridle. But we also knew that a pulley could make the kite feel a little less crisp and responsive. Fortunately, combining the pulley with a stopper – as we’ve done on the Neo and Dyno – allowed us to keep both the pulleys and the crisp bar feel that we were looking for.
Juice in summary
Steering / turning
Moderately narrow arc and wide tips give super-quick turning.
Drift / hover
The low weight, low strut count and low center of gravity of the Juice keep it very stable in the air. It flies well in the lightest of winds and resists stalling, both front and back, better than nearly any other kite.
Owing to the smooth, round turning and short bar stroke (for kites this big), the Juice has consistent, linear, sheet-go power delivery.
The high aspect ratio helps deliver quick, easy depower.
We’ve minimized materials where possible on the Juice, so keep the weight down, but have included all usual reinforcements.
Dyno 2013 - What's new? by Ken Winner
Low weight is a key feature of the Dyno and all measures have been taken to strip out materials that do not contribute to on-water performance. For example, there is no single-point inflation system on the Dyno simply because SPI increases weight without improving performance.
The performance benefits of low weight are mainly:
(1) the Dyno will easily fly when quite underpowered. The 17 will readily stay in the air when there is too little wind for an 80-kilo rider to plane on a big race board.
(2) when flying the Dyno up and down for power (as when racing downwind), the Dyno's low weight helps it to make a powerful upstroke.
Aspect ratio remains low enough for quick turning but high enough for good aerodynamic efficiency.
While the Dyno will work as a 4-line kite, it retains 5-line ability for these reasons:
(1) Easy relaunch in light winds. Even riders who like four-line kites often add a fifth line to make relaunch possible in super-light wind.
(2) Safety. When you need to get total, complete and perfect depower in half a second, nothing else works as well as a 5th line.
(3) Easy, safe self-launching and self-landing.
Thin tapered struts with semi-segmented and conical construction
Struts are tapered from a fairly large diameter where they meet the LE to much smaller diameters 25% back. The big joint with the LE gives more rigidity to the structure of the inflated elements. The taper to a smaller diameter provides lower drag.
The semi-segmented construction gives a smooth upper curve to the struts – an aerodynamically superior shape – while taking up excess cloth and preventing unsightly wrinkles in the lower surface of the strut.
The struts go to a conical construction at the 25% point. This eliminates seams and therefore removes a point of potential seam failure in the part of the strut that bends the most on the beach.
The 2012 Dyno has seven struts for extra stability – mainly appreciated by heavier riders taking the Dyno to the limit in powered conditions.
The 2013 Dyno is more narrowly focused on racing, which requires more flexibility and the lowest possible weight, so the new Dyno has only five struts.
The tip strut is closer to the tip to support the thin leading edge and provide stability during hard turning. The quarter strut is a bit closer to the tip strut so as to support the flat section of canopy between tip and quarter struts.
The large span between quarter and center struts provides the bulk of the power of the kite. This area is not heavily controlled with struts because it needs to be free to luff or fill, depending on wind strength.
More and different sizes
The Dyno was originally a light-wind kite but has evolved into a light-wind and race kite and now comes in sizes 7, 9, 11 and 13 in addition to the original 15 and 17.
The new 17 is larger than the 2012 Dyno 17 and has significantly more power. Sizes 15 and 13 are also more powerful than corresponding Dynos from 2012.
Graduated cloth weight
The inflated elements of the 2012 Dyno were entirely built of a light but extremely stable new Dacron. For 2013 we are keeping this lighter Dacron in the small-diameter inflated elements – the struts and the tips of the leading edge – while going with our standard, heavier-duty Dacron in the large-diameter parts of the leading edge. This heavier Dacron permits higher inflation pressures and thus greater stability in the leading edge.
We've added more segments to the geometry of the 2013 Dyno. This helps ensure good fidelity to design shape.
Owing to the fewer struts and lower weight, turning speed has been improved. This is most noticeable when flying the Dyno up and down on a deep downwind point of sail.
Leading edge diameter
Leading edge diameters are basically unchanged in the center of the Dyno but tip diameters are smaller. This change provides a bit less aerodynamic drag.
The new Dyno bridle has no pulleys. This gives a bit less weight and drag but also means that the 2013 Dyno must be flown on either (1) a 5-line bar or (2) a four-line bar with front-line safety leash.
Canopy profiles in the outboard quarters are quite flat for low drag. Canopy profiles at and between center and quarter struts are deeper and more powerful than in 2012.
Power vs. depower
The various changes have led to better power and depower.
The lower weight, deeper profiles and new geometry help the 2013 Dyno to relaunch quickly.
Sky Solbach Dyno:
"The new Dyno is something totally new and is hands down the fastest kite I have flown to date. It constantly shoots to the edge of the wind window while maintaining really consistent power delivery that carries you upwind. Downwind, the new Dyno is equally impressive. I can't wait to see what the North Race Team can do on the race course this year with this tool in their hands!"