I never liked Rebels, but I must say some answers from a quote below are good.
1. Been playing with straight struts for a long time and they do allow more breathing of the canopy and I have them on bigger kites. Recently I'm OK w/o them since I've reduced number of struts.
they looks like this
2. I couldn't find very big issues in having straight center LE... TE naturally didn't follow it quite OK but only small mods were needed to fix that.
3. Longer straight LE segments actually are good in tips. I wonder why North still uses TE battens there if they're almost flutter-free?
Dan-at-North wrote:Regarding the four vs. five strut debate and Geotech discussions posted here and elsewhere, the designers have this to say:
"One of the reasons we liked the four-strut configuration of the ’09 Rebel was that eliminating the center strut permitted the broad center section of the Rebel to luff completely when the kite was depowered. This gave better power and depower – more of a “pop”, more of a crisp and quick on-off in the canopy power – when pulling in on the bar or letting out. At the same time, this more complete ability to luff in the center of the canopy gave all sizes a smoother, less draggy feel.
We were determined to keep both the good depower and crisp feeling in the 2010 Rebel, but thought that staying with a four-strut design, while fine for most riders, was too close to the edge for some. The answer was to move the quarter struts slightly farther from the center – thus enlarging the luffable center area of the canopy – and to place a straight strut in the center position.
We had dabbled with straight struts back in the summer of 2001, and we have prototyped with them occasionally over the years, but have never before found the right circumstances for gaining a clear advantage from them. However, with the new 2010 Rebel protos we could see that the tip and quarter struts were providing good profile stability while the straight center strut was adding enormous stability to the leading edge tube without robbing us of the large luffable area.
Combining the wider luffable center area of the canopy with the extra leading edge support from the fifth strut gave us, in short, the best of both four- and five-strut worlds."
For those who don't understand what Ken means by "straight strut" the easiest thing to do will be to go check a 2010 Rebel out, and take a good look at the center strut. You'll notice that it's not directly connected to the canopy, but sits several inches off of it, which allows the canopy to act as though there were no strut there, while the LE still has the added stability of the center strut. I think it's a rather brilliant solution to the difficult problem of trying to balance between the added stability of a center strut and the added performance of four struts.
As far as the "Geotech" claims, Ken has the following to add:
"The change in geometry that is shared by all 2010 Rebels is the reduction from three segements to just one segment in the span between tip and quarter struts. This is an idea we have tested and revisited over the last 5 years, but only now have hit upon the right way to do it.
From our testing, and from observing some other kites on the water, we knew that having too few segments through the center part of the kite – the part that has the most curve in the arc – has undesirable effects on canopy profile shape. Therefore, we knew we didn’t want to use single-segment geometry through the middle of the kite. However, nearer the tips, where the arc of the kite is normally not so curved and where flat canopy profiles are desirable because of their resistance to fluttering and flapping, the single-segment approach makes sense.
The result of this use of single-segment geometry gives canopy tips that are cleaner, less draggy and nearly flutter-free."
The final word, however, will always come from on-the-water testing, which is where Rebels have always done their best. The kites should be released in September. Contact your local for a demo.