September 2013

                                                     AN UNEXPECTED JOURNEY.

                  PATENT APPLICATION  NZ 614908, 30 August 2013,  FOR A SINGLE SKIN FLYING WING

                                And, might I add, particularly for a traction kite version thereof!

Not at all what I had expected to be doing this winter, but then again  kite development wasn't exactly what I expected to be doing with my life either, until it was.  Kites are some sort of recurring condition it seems; like malaria.

And it's been a surprise from another direction as well;    A few years ago I wrote something like: "The useful forms of traction kite have now all been invented, the future will be about improving these existing designs..." Back then, the type that I expected would eventually dominate was the rigid aeroplane style flying on a single line with radio control).  I still think this is the future, but as of 2013, they remain unavailable and largely unknown outside the kite-energy field.

But around 2 years ago  I began to see a strong possibility that steerable single skin soft kites could take over significant sections of the traction kite market that are now serviced by ram air inflated 'foils and LEI's (leading edge inflatables as used for kite boarding)- and create a few new markets as well. 

Soft single skin kites have a long history, traceable from simple parachutes that were made increasingly steerable by distorting and venting their canopies.  The Barish sail wing from the early 1950's was a notable early success, but largely overshadowed by NASA's development of the Rogallo flex wing through to the now ubiquitous NPW (Nasa PowerWing) kites in 2 and 4 line form.  NPWs are renowned for their pull and light wind flying, but don't have great L/D and are on the verge of stalling all the time- to the extent that they not infrequently decide to fly backwards, which can be rather disconcerting, and occasionally dangerous.  It's surprising that NPW's have so stubbornly resisted improvement- even after 30 years of development by very many people (including Chris Brent and myself here, who made a somewhat successful attempt at getting some power control from them around 2005).  

More recently, parapent designers approached the problem from a different direction- by  taking the lower skins off their multi-celled high performance ram air wings .  Until a year or two ago, these wings were regarded with some scepticism and no little alarm, but have now gained wide acceptance as safe and useful.  Useful in that 20sq.m versions can weigh less than 2kgms and pack small - so have become popular with mountain climbers who'd rather jump off than climb down.  Single skin parapents (plans for which are now freely available on-line ) are typically high aspect ratio (by kite standards), have very many cells, and a huge number of bridles, each attached to a tiny triangular flare.  Their top skins wrap over to form a leading edge shape similar to that of ram air inflated 'foils.  They don't have a lot of power control (being rigged to fly at sufficient angle of attack to ensure pressure under the wing) but their L/D approaches that of lower performance ram air wings.

Early in 2012 I made a single skin kite of the parallel ribs type and then another- which showed plenty of promise, sufficient for me to make a strong case to Vlieger Op (PL traction kite licensees) that they should develop kites along these lines-  or get left behind when others did.  Michel Dekker at Vlieger Op is (in my view) the world's best 'foil kite designer and right at the peak of his talent; definitely the right person in the right place at the right time to do this.  Didn't happen though, Michel made some prototypes and sounded plenty excited at times, but other development priorities then intruded and by 2 months ago I'd lost patience.

Since then I've developed my original concept through 13 more prototypes, spurred by a serendipitous discovery; excellent power control and complete luff resistance.  I didn't set out to make a single skin kite with these characteristics, had thought this impossible, but I'm very pleased to have been wrong about this.

Trying to get a theory that explains their performance has been the most interesting part of the journey.

By a month ago, I thought I had it all figured;  designs ready for production and a patent application ready for filing.  Then, from scepticism born of long experience, I tried cutting off  the cherished features that I believed were providing the power control and luff resistance.  If anything this kite then flew better, and didn't lose any luff resistance or power control at all.

The Greek chorus down the back here (staff and bosses at Peter Lynn Kites Ltd) seem to find this absolutely hilarious for some reason.

But it has now led to an even better-and simpler- design- and a believable theory as to why they have 100% luff resistance. 

Which is that the luffing virus that used to be endemic here died out through lack of hosts when I shifted focus to single line kite stability from about 2005.  Thinking back, I can now see that it did try to transfer to single line kites, but never really took.  Anyway, we're free of this virus here now, which is a great relief. 

No really, I do now have a theory that fits and has so far successfully predicted the effects  of various changes, and this became the basis for the patent filing (yesterday). 

I'll  probably look for more than one licensee this time because even compared to Peels, C Quads and Arcs, I have a sense that this kite is special- though rather alien to me because it's not at the high performance end,  which I've always previously gone for. 

They're special because they're so simple (just one skin, 6 ribs and 22 bridles on current 3.5 aspect ratio versions), because they're so easy and safe to fly, because they have more pull for size than 'foils and most of all because they fly in just half the wind that any other kites except NPWs require.  

Not that they are perfect; L/D is no better than an NPW at this stage of development and they are rather ugly - especially when fully depowered with the wing tips flapping.  Neither do I yet know for sure how well they'll scale up- or suit bar rather than handle flying. 

What will they be used for?

Beach shop kites and training kites first of all, and buggying of course, and snow kiting- especially transcontinental journeying.  Quite probably there will be on-the-water applications as well; for low wind kiteboarding, and for pulling boats (they fly happily off their bridles), and these are just the kite versions.  Parachuting,  parasailing and parapenting are other obvious applications.   

Need a name too, and here are some of the candidates; :

Zombie - because they rose from the dead (the 2nd prototype lay forgotten for nearly two years ), and you just can't kill them.

Vampire: because they're going to suck the blood out of the entire kite traction industry.  At half the price or less, manufacturers and shops will need to sell twice as many just to stay even. 

SS: standing for Single Skin and Swan Song- nah, I'm not even nearly done with kites as yet  .

BS  for Black Swan (no, not bullshit, silly). "No matter how many white swans you see, this doesn't prove that there isn't a black one out there somewhere."  Quite appropriate I think.

But is it really as good as I say?

No, and yes, the average of which is; I don't know.     Time will tell!

So where can you get one?

You can't as yet- soon though, and if I can contrive a way to do so without having to spend the next 10 years being a policeman I'd really like to allow non-commercial making- not least because of all the fresh thinking this taps into.

Peter Lynn, Ashburton New Zealand, 1 September '13

*A statement of "absence of evidence is not evidence of absence" made before West Australian black swans were first sighted by Europeans.