(Very) soft kites...

Hi Guys,

Research report on single skin kites.  (Apologies to those of you who have seen some bits before.)  And bin this one and let me know if you don’t want to get this SPAM any more.

Exec summ:

  • Launch from sock from pilot kite has potential – not sure how to fly a kite back into a sock yet
  • Dynamic reefing looks very plausible
  • Still developing control systems for big kites
  • Pilot launch (video about 10 seconds)

I think this is very cool.  Albeit with possibly limited applicability due to there being no obvious retrieval method associated with it.   Credit to Alec for this idea. 

The SS kite is stuffed inside a sock which is attached to the line of a pilot kite – single line stable kite.  The pilot kite is flown to an altitude at which the SS kite lines are nearly tight.  The SS is then pulled out of the sock  and it inflates itself so quickly that it flies before dropping out of the sky.  (I use the term inflate perhaps somewhat loosely here.  Remember, with these kites, there are no enclosed structures that hold pressure, whether bladders or ram air cavities.  But I think inflate is still the right word.)  This test was in quite light wind with relatively short lines.  I think in reasonable wind it will be quite robust.

Although the launch procedure looks good, I think the only way to fly the SS back into the sock will be by reversing the video!  Any ideas for a recovery strategy, which doesn’t involved dropping the kite in the water, would be much appreciated…..  Actually, perhaps I have an idea.  We could deploy the pilot again but this time with several dry grass runners hanging from the pilot line.  Fly the SS within bridle range of that and the grass runners are sure to cause enough bridle tangles to stop it flying!  (In fact, why several runners – from my experience, just a few would be sufficient!)

Dynamic reefing (video about 25 seconds)

These kites open up so quickly that it seemed worth trying reefing in flight.  This test was with a 2m with a reefing line tethered to a park bench at Victoria Point.  The reefing line connects to 4 loops, each of which goes through 5 central ribs, separated across the chord of the kite – so as it is tightened (in this case by me walking downwind while holding the flying lines), the loops pull the centre of the kite into a concertina. Although it didn’t fly very well in this configuration, it wasn’t too bad.  Reinflating was by walking back upwind.  I was happily pleased with the performance. 

I have a booking with my sail maker to put reefing lines in the 16m later this week.  At this stage I don’t know how we’ll launch that on the boat without reefing.  I’m hoping that reefing will allow a beach launch, transfer to boat, sail out to reasonable water, shake out reef and go.  Reverse for when returning to shore. 

If that works, it should be possible to eventually launch to short lines from the boat with the reef in, ease flying lines from winches to get the kite in the air, then open the reef etc.  Keeping the additional reefing line at the right tension could be problematic – I think I have a solution for launching.  Not so sure about when retrieving….though I’m working on something.

Big kites – bar control system

Lots still to learn, but I still think they have potential.  I was reminded of the potential in fact when I was testing the 16 at Murarie (more on that choice later) in no wind on Sunday.  Popped it hard enough to get it off the ground then there was a knot or two of breeze and it flew to zenith.  I was sure it would then collapse – but, no, a 4 knot or so gust (I guess).  Perhaps it was more but it didn’t seem much – but is it really possible to get lofted in 4 knots with a 16?  Quite amazing, not to mention a tad surprising for this old guy, to wonder why my feet were not still on the ground where they should have been!

So the weekend was largely unproductive due to lack of wind.  Alec, Marcel and I tried the high AR depower 12 at Birkdale (fields near the tip – high enough to have better breeze than most places) with a new control system. This is the kite I had to let go in the drink last week as I couldn’t hold it.  It was tethered to the boat, but I couldn’t hold the rear line tension.  First attempts on Saturday were with it tethered to a star picket – that was abandoned when it was being pulled out of the ground.  Then tried a harness with a 5th line safety tethered to a star picket.  The 5th line safety came into play on each launch, even though Marcel was holding on to my harness – ie we couldn’t hold our ground on launch so got pulled far enough for the 5th line to get tight.  It must have been less than 10knots.  One last attempt with it tethered to a fence post – showed potential, but the breeze direction changed so that the fence itself was well in play….so that was also abandoned.

I took them to Murarie on Sunday, having inspected the site on Saturday.  The grassed area inside the cycle track is very large.  Importantly, it has some shelter structures, with steel legs that seem very well concreted into the ground, that can act as tether points for any wind direction.  I’ve actually seen kites there quite often.  Two quite frustrating trips there were unproductive due to lack of wind.  The brief flights suggested that the bar setup might work – albeit it will feel quite different and take a bit of getting used to.  I’ll try further this week if there are a few knots sometime.

All the best,