THE CUTTING EDGE OF KITE FLYING IS RETURNING TO THE EAST.
And not just because that's where Kevlar's new home is (must have been finally kicked out of Germany)!
I've said this before, but it's worth repeating;
It is rather embarrassing when us 'professional' kite fliers are upstaged by a bunch of kids and their parents flying $2 kites.
Which happened at Chengdu two weeks ago, every time the 'professional' kites dropped out of the sky through lack of wind - which was quite often.
The organisers would then, sensibly, open the flying area to the public and we'd be immediately inundated by hordes of kids squealing with delight while running in every which direction with small deltas- some of which would then rise through the melee to float hundreds of metres above us all in a distinctly mocking way.
How is it that these small cheap commercial kites can fly in less wind than any of our big expensive inflatable show kites and the best pilot kites can sustain in?
Some of them are even a match for specialist light wind framed kites like Genkis and such.
And to cut off an answer that may have been forming about now, it's NOT because they are lighter in relation to their size (the Charlie Brown 'ounces per square foot' metric). El cheapo deltas are not lighter for their area than ripstop nylon kites with carbon frames, and they are substantially heavier per sq. metre than conventional ram air pilots.
Nah, I can't think of any aerodynamic reason why this would be so- the opposite in fact.
Has to be shape then- that they are better able to generate proportionately more lift and better able to resist stalling in the critical 5km/hr to 10km/hr wind range.
This is a function of camber (concave lower surface) which deltas et al have- while most ram air inflated kites have convex lower surfaces. It doesn't require high faluting aerodynamic theories to understand how this works; with a cambered lower surface, arriving wind is gently re-directed in such a way that the resulting pressure increase and momentum transfer lifts the kite. In contrast, wind that encounters a convex lower surface piles up against it creating more drag than lift. Of course both these types of kites may have similar flow over their top surfaces- and therefore get the same lift contribution from there, but superior lower surface flow makes the difference for the delta type in very light conditions.
Sure, ram air inflated kites can easily be made with cambered lower surfaces, but then they have too much lift in mid and strong winds- and become unstable. Deltas deal to this by having wing tips that twist off to reduce lift in stronger conditions.
And yes, I've spent years trying to develop an equivalent for pilot kites, but with only marginal success so far. The 9sq.m and 11sqm Airbanners Lifters are the best I've managed to date. The 11 sq.m (confusingly, and for some reason unknown to me, it's generally called a 12metre), after extra development by Stefan Cook, is pretty good in light wind, has excellent reliability in gusty conditions and a wide wind range- which makes it a favourite with large show kite fliers. But it's no match for many $2 kid's deltas in the light.
There is one soft kite which will fly in slightly lighter winds than the 12m: Mr Ma's "Ladybird".
This kite, (and his Grasshopper Head) are different to most parafoils in having triangular cells.
Which appears to reduce the Ladybird's stall speed just enough to be useful, and again, it's a lower surface effect I think. Except that this is probably just another half-baked theory as his Grasshopper Head also has triangular cells, but isn't quite as good in the light, though it is a superb flier across the range.
After Chengdu came Tongren, (Guizhou Province) an even larger event, but very different.
The wind at Tongren wasn't light, it was absent.
So we used 200 large balloons (and around 80 cylinders of compressed Helium) to lift our show kites instead- which put us back into the ascendency over those embarrassing $2 deltas. Though show "kites" may be an incorrect description in this context, show "hangs" would be more accurate.
But there's another factor in the embarrassingly good light wind performance of small cheap kites in China: They are, in general, competently flown. I've repeatedly noticed that for children in the West, kite events very often end in broken kites, huge tangles and tears of frustration. At Chengdu, I was able to traverse the entire field from left to right with an 11sq.m pilot; over, under, and around hundreds of small kites being flown by children and their parents, eventually getting to my anchor at the far side with a clear line. Maybe this would have been possible also in Indonesia, and India (except that in India I would have been deliberately cut down within seconds), but in no way would this have been possible in NZ or other Western countries. Actually I'd rather mix with the kids than with the grown up's in China because the adult kite fliers there are wedded to Kevlar- it's everywhere. Even when I leave an event with apparently intact lines, they break at the scars and cuts the next time they're taken out in strongish winds,. I make my views on this loudly clear of course, but it's likely that this will result in my becoming 'persona non grata' there far before Kevlar is.
But there really is a kite culture in China- and it's in the process of being successfully rolled over to the next generation. All the happy excited kite flying kids there says this is so. That they are out of their high rise apartments, into the open air, enjoying precious one-on-one time with parents- who work much longer hours and have less holidays than Western parents- is the cement in this.
This is a strong reason to believe that in future, China will once again be the centre of world kite flying- and where kites are being flown is also where the market will be, and not just for the $2 kite either.
There are aspects of Chinese culture that I really don't like- such as too many bones in the fish for example-but their general friendliness, passion for kites, and especially their increasingly innovative designs, make it, for me, a place worth visiting.
See you there sometime?
PETER LYNN, ASHBURTON, APRIL 1 '16.
Single skin update: After A LOT more development, a 20m SS Octo is now flying well in very light winds. It also flies well in strong winds, but not, unfortunately, with the same bridle setting- though the adjustment is by shifting a single larks-head knot. The key tool was to use two initially identical kites so that every change could be checked with side-by-side flying. That this standard of testing is not really possible with just one kite is because wind is never the same from one minute to the next.
To my considerable surprise, the single skin leading edge is consistently superior to using a ram air inflated leading edge collar- in every wind. I added and then removed collars of different styles 3 times before being convinced of this.
Serpents with leading edge collars are still flying better than those without- albeit that they don't fly as well in light winds as the latest Octopus. Maybe they are also more solid above 50km/hr or so.
Whether this is causative or not, the change that facilitated light wind flying and reduced "falling off' (the annoying tendency to fall of completely to one side of the window in failing wind), was simply to shift the kite's centre of pull closer to the leading edge by shortening each of 10 bridles to the leading edge by around 100mm. In stronger winds this causes leading edge collapse- hence the requirement for an easy adjustment. It may be possible to use elastic elements in such a way as to make this change automatic but this will likely cause luffing in strong turbulent winds unless some sort of 'slow' spring can be devised; one that takes at least a few seconds to react to changes in load rather than doing so immediately.