Rokkaku

I have had a bit of a love-hate relationship to Roks - I love the simple, elegant form and it is a great canvas for appliquing; but it took me a lot longer than expected to figure out the details required to make it a well-behaved flier.

The Rok's simplicity is misleading: there are enough variables to adjust to make it hard to isolate cause and effect. Small alterations can make all the difference between a stable flyer and a manic looping kite.

Here's a list of my current preferences:

• 6-point bridle
  The 6-point bridle makes bridle-tuning quite a chore, but it has advantages over the 4-point bridle. It gives you more control over the Rok's shape under wind pressure - not so relevant for static flying but very important for fighter-Roks. 50% more bridle points also help to distribute the pressure more evenly - you can get away with lighter rods than would be required for a 4-point setup.
• bowing of upper and lower spreader
  The standard rule is to bow the lower more than the upper spreader. Don't be too timid, you really do need a pronounced bow. The most convenient set-up for me is to put split caps on the spreaders which go into spar pockets. This gives you a nice clean shape without any spars jutting out. Also it avoids any unneccessary straining or distortion of the sail which can easily result if the bow line is attached to the sail.
  I'm still not quite satisfied with the tensioning mechanism. I've tried various kinds of sliding tensioners and none seemed really reliable. Fixed tensioning points, on the other hand, can't easily be adjusted to match the prevailing wind conditions or desired flight characteristics. Now I'll try a back-to-the-basics sliding knot ... let me know what has worked for you.
• sail billow
  This is, in my experience, the least critical point. The proper billow develops automatically as a result of the frame construction and bowing. I was cautioned not to make too heavy a seam, because it would not stretch as much as the sail and would hamper the formation of the proper billowed shape. In practise I have found this is not really a problem: I use a standard double seam.
• bridle-tuning
  I find Roks to be quite sensitive to minor adjustments of the flight angle: tow point too far up and they start swinging and looping; too far down and they're sluggish and won't rise.
• framing
  Initially, I had all-carbon frames. Recently I replaced the spreaders with fibre glass tubing, using carbon only for the spine. The increased flexibility puts less strain on the sail, makes the kite more resilient to changing wind conditions and overall just more stable. For small Roks solid carbon could be an alternative - but I doubt whether it would be much of a gain in terms of weight or durability.
• aspect ratio
  So far, I have always used a 3-4-5 aspect ratio. This is the true Rok, as far as I am concerned. I suppose a 4-5-6 ratio or an enlarged lower triangle would result in a more stable kite, but I haven't yet tried either.

Big Roks

I have built large static Roks according to plans by Simo Salanne and Charlie Charlton. They are each about 1.5m by 1.2m, Carrington and carbon/fibre-glass frame.

I don't usually use Carrington, since it has more stretch and absorbs more water than Icarex does. It is nice, though, for "show kites": it doesn't crinkle at all during sewing and has a nice silky look from up close.

Charlie's design: This kite was built as a wedding present (kind of obvious :-)
(8K) (9K)

Simo's design: Another wedding kite (not so obvious). The glyph is the chinese symbol for Chi, loosely translatable as "life energy". The blue and red areas symbolize the elemental forces of fire and air.
(44K)

Little Roks

This one is really small, with a 75cm spine. It is primarily meant to be a fighter Rok. I haven't yet participated in a real Rok battle, but I do like to zoom around a fighter kite every now and again (check out my fighter kite page to find out about other types of fighters).
The spine is 4mm carbon, the spreaders are 2mm fibreglass. I initially used 3mm spreaders but these proved to be too stiff: the kite did not respond properly. Of course, if you're just flying it as a static kite 3mm is fine.
The sail is Icarex applique. The Navajo design was a result of my '98 trip to the south-western states of the US.
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