Douglas Adam's Hitchhikers Guide to the Universe claimed the answer is 42- but was a little uncertain as to the question.
42 definitely is the answer to one little corner of all of these things: Single line single skin kites (SSSL's). And the question asked is clear: Can a single skin single line kite be made that is practical and useful?
To reprise; SSSL 24 (42 backwards you'll note), from 4 Nov '14, eventually flew reasonably well across the wind range, and in gusty conditions- the first fully functional SSSL I've had, and maybe the first ever.
This is a big deal, because once one of something new works, success is pretty much assured-even if eventual solutions are quite different. It's like what the Wright Flier did for the aeroplane- even though the Flier had very few features that are now mainstream except for an engine, propellers and wings.
But after 24, I went back down into the swamp and blundered around in the dark for a while until getting onto firm ground again from number 31 (Dec and Jan Newsletters).
By 35 (2 Jan '15) performance was generally better than our current ram air parafoil style pilots. Very exciting! There's nothing quite like being on the right side of new and disruptive technology, even when it's your own products that are likely to be superceded.
By 42 the design was refined sufficiently for 43 to be made with almost no changes- first time in this series- not that this is now a completed body of work, no development program ever is.
The only doubts I have as to 42 really being the answer to everything is that it's green- and I'm fairly sure that green isn't the answer to anything. Religions (like Greenism) just provides another excuse for people (and kites, see below) to behave badly, and we have quite enough trouble being good as it is (as do kites).
SSSL's an invasive species, Nelson January 18 2015.
35 to 43 have great wind range, huge pull for size, better flying angle than pilot kites, really good gust tolerance and are so easy to launch and fly. Unlike ram air kites they 'inflate' immediately.
In 70km/hr winds 39 (10 Jan, 30gm/sq.m fabric) pulled 37kg and weighs just 250gm; perhaps a record?
To my surprise (everyone's I expect), they fly like Rokakus- zoom up fast when line is pulled in, float back without losing form when line is let out- and in light winds can be controlled in classic fighter kite style.
They also do something else unexpected: They boom like a drum or gunshot when the flying line is plucked- even in quite light winds. Not quietly either. The pitch seems to be a function of kite area not wind strength so I'm hopeful of having a kite based percussion orchestra that will at least manage the opening bars of Tchaikovsky's 1812 Overture - boom booom boom BOOOM. Hence the name: "Boomers".
ST's Ray and SSSL42 at Nelson, January 2015.
At the 24th Nelson Kite Festival in Jan '15, there were 5 Boomers in use as pilot kites by various people.
In mostly quite strong wind, some light patches and not always smooth, they performed pretty well, as they did at Goa, Pune and Dubai later in the month. Goa and Dubai's perfect winds were no test for any kite, but at Pune there was no wind, only periodic thermals- and the Boomers revelled in this- as did Andreas Fischbacher's latest Maxi Manta- what a kite, the best light wind large show kite ever, and by quite a margin (see Nov '14 Newsletter).
These boomers were prototypes between numbers 35 and 43. Earlier ones fly as well as later ones: which is good in that insensitivity to small differences is a marker of successful design, but not so good in that I'd deluded myself into thinking that each new kite in the series was significantly improved.
42 and 43 do flap and rattle a lot less than 35 though.
But as the saying goes; one swallow does not a hangover make -or should this be something about spring?
I do have some concerns:
Though not at all fussy about fabric weight, stiffness or porosity, they are very sensitive to bridle and fabric stretch. At Goa on the 24 Jan, 43 became entangled with a church * - which is not good for kites (or for people) I reckon. After the strains of this religious experience it behaved badly, diving suicidally off to the left. Intense re-education has helped, but I suspect residual jihadist tendencies- it remains on the security watch list for now. Hopefully it's just immaturity.
Boomers currently have 26 bridles- which is a lot- but they are all exactly the same length. And I mean exactly: 3.0m +/- 5mm! At present the only way they'll fly straight in very strong winds is by continual adjustment until everything settles in and stretches out. If required, left/right tuning is then by shortening one rear outer rib bridle by up to 20mm.
Until a way is found to make them less sensitive in this respect, volume production will be a challenge.
Another concern is that the rear panels flap noisily in strongish winds. Enough to cause noticeable fabric softening in just a day or two. Nor can this currently be solved by reshaping the fabric or tightening the trailing edge, as this flapping is the only solution I have so far found for a strong wind instability effect. Which is that if the camber is carried through to the trailing edge (all of the 60mm of camber is currently in the forward 75%), in strong winds the kite flies at a flatter angle of attack (higher flying angle), causing the leading edge to collapse. Having the rear 25% of the kite flap in stronger winds destroys its contribution to lift, causing the kite to fly at a slightly higher angle of attack (lower flying angle), which prevents leading edge collapse. There may be other ways to accomplish this- like spring bridles- but I haven't found any yet.
There is also another problem with rear camber; that in stronger winds, flow becomes attached over more of a kite's upper surface, shifting the centre of pressure progressively rearward. This causes "roll-over" instability (ROI)- an inexorable dive over to one side or the other as wind speed increases. Adding more camber to the rear to reduce flapping is probably not an option for Boomers because they appear to be close to having an ROI problem- though this does seem to recede as the fabric softens.
Concerned that fabric stiffness was a factor in their ability to hold shape, from 35 they're larger: 2.5sq.m of lifting area (up to 34 they were smaller). Much to my relief, leading edge stability was not affected. As a further check, very light stretchy quite porous fabric (30gm/sq.m) was used for 39- and it flies as well as any of this series, especially in strong winds. Nor has it been necessary to add stiffening of any sort (most single skin traction kites use weed whacker cord to stiffen their leading edges). I don't expect any problems with further scaling to at least 10sq.m., but no doubt there'll be some limiting factor.
The last time I can recall having the same road-to-Damascus feeling about a single line kite was back in 1974 when I was making polystyrene box and aeroplane styles. To my view then, their performance was stunning; so much pull for size, incredibly high flying angle, rock solid stability, singing lines. I remember lying on my back in the long grass for hours just staring up at them mesmerised- which did attract some comments of the 'not exactly adult behaviour' sort ( I was 27 at the time). It puzzled me then as to why people didn't queue up to buy them. Too fragile I thought, but I was wrong about this- small polystyrene aeroplane kites are now ubiquitous throughout Asia, there are zillions of them at every festival. In hindsight, it was just youthfull impatience (not to be confused with the fully developed adult impatience I have now).
Kite Bali 2007.
But in the 41years since then I've had many enjoyable challenges developing small and larger framed fabric kites, then soft theme kites, and especially traction kite stuff. But neither the sticked single line kites nor any of the ram air show kites (like the Octopus) have quite the responsive 'joy of flying' of either those original polystyrene box kites or these SSSL Boomers now. Who says you can't re-visit your youth!
PETER LYNN, DUBAI, 1 FEBRUARY '15
SSSL 43 Religious Experience.
*Mount Chapel, Portuguese Goa, built in 1519. 43 was caught by two large decorative marble balls and a small tree growing out of its roof. Fortunately, workmen doing restoration were on hand to release it.