Building/learning what makes a kite go, learning to fly, and learning bamboo is one thing. Purposefully designing a kite for a specific task is quite another. That task was to build a competitive fighter kite. After a while, I''d learned some building skills from Brian Johnsen and Johnny Hsiung. Brian and Johnny used similar building techniques and materials which prompted me to follow suit. Synthetic materials offered more easily repeatable and speedier results - so the eventual small adjustments I'd encounter would be dealt with more readily.
I had a Stafford Wallace kite that I flew the wings off of. Really liked the kites handling at 3 kts. to 5 kts., but wondered what would be involved with building a similar handling model that flew in a higher wind speed range.
At that moment I became a kite experimenter.
Beginning with a previously known quantity, I used the Stafford kite as a starting point. One thing that intrigued me with the Indian fighter was its shape. The colorful materials and appliques of Indian kites are interesting, but to me a certain preoccupation lay in the form and proportions. Although electing to stay with the size and shape, I immediately encountered a problem that stemmed from using the carbon fiber bow. Comparisons between a double tapered bamboo bow and a straight carbon fiber will reveal, when bent, different bow shapes. Since the leading edge of the kite is in part, defined by the shape of bow, I needed to fudge a little. The width of the kite (wingtips) and the point at which the bow crosses the spine ( upper bridle point ) are also defined by the bow. By the time I had the bow cut to length to accommodate these three points, the leading edge curve became slightly altered. The spine was made from 0.060 carbon fiber and aluminum tubing, the bow was made from 0.070 carbon fiber and the sail material was a heavier variety of Mylar. The kite was bound with tape and glue - the bridling system was three leg.
My kite was not a Stafford kite at all, but when it was stacked atop a Stafford, the two kites were carbon copies in size and shape, with exception of a slightly different leading edge curve.
The 0.070 bow was a lucky guess. Anything more or less in the way of a bow would not have worked as well. Because of the stiffer bow, sail and spine in conjunction with its ample size - the kite flew in lighter winds (with some work) and may have even been a good indoor flier as well. It did, to my great pleasure, fly its best in winds ranging in speed from about 5 kts. to 9 kts. With an increase of pull, the kite was a lot of fun with 600 ft. +/- of flying line deployed also. The added weight of my kite made available more momentum, which enabled it to fly farther off wind at closer distances. ( did my first 360 with this kite ) Being a very fun kite, it was a bit of a tank; at least competitive wise, so I grabbed a calculator and went back to the drawing board.
What I wanted to do was adjust the ratios of the kites measurements to seek optimal performances at various wind speed ranges. It occurred to me there would be some obstacles. Say for example: If I wanted the ratios reduced by 10%. No problem. All that need be done is multiply all the measurements by 0.9. That would work well if materials were available in many sizes. The more obvious hurtle was that carbon fiber rod was only available in certain diameters. 0.030, 0.050, 0.060 and so on. To accurately reduce a 0.070 carbon fiber rod by 10% would mean trimming 0.0035 inches off around the circumference to produce a rod that measured 0.063; a difficult task. The nearest available rod size measured 0.060.
The solution was to use the diameter of available carbon fiber rod sizes as a starting point to adjust ratios and proportions. Since I had no way of measuring the thickness, weight or pliability of Mylar or some properties of the spine - that would entail a little guess work.
The first go at a reduced size of kite began with a 0.060 rod, bamboo spine and a lighter weight Mylar. Interestingly enough the kite came out a bit stiff. In my minds eye I visualized the resulting kite being a more nimble handler in the same 5 kts. to 8 kts. wind speed range. To my surprise, the kites wind speed range was 9 kts. to 12 kts. I went back to the calculator using about a 5/8ths inch increase in width as a basis for an increase in overall area and a longer flimsier bow.
The alteration was just the ticket. The kite flew well in the 5 kts. to 8 kts. wind range. Playing with slight variances in size, I discovered what little alterations were necessary to effect the wind speed range and handling of the kite. Further experiments with kite sizes based on bow diameters also gave interesting results. Using a 0.090 rod for the bow and the heavy weight Mylar sail, made for a kite with very syrupy, slow forward speeds. The kite would be a good one for beginners because control input reaction time was increased. Smaller versions revealed increasingly quicker turning kites. It was necessary to slow the kite with bridle/spine adjustments just to be able to keep pace with the speed. On the smallest version, I used a 0.030 rod and a very light Mylar.
By this time the outcome of experimentation was becoming a tad more predictable. The two smaller and the largest versions were discontinued to concentrate on kite sizes evolving from the 0.050 and 060. bow diameters.
As much as I played with aspect ratio, the kites always wanted to return to the classic Indian proportions. To this day my cross-spared kites maintain Indian style proportions with regard to lengths and widths. Then I toyed with the previously mentioned size variances in addition to different sail materials, shapes, balance, bridling anything I could think of to effectively improve flight characteristics.
One of the challenges with learning fighter kite was transcending dogma. Some people whos work I admire, respect and stole from, of course, had theories and ideas they readily shared. The key to taking the best and leaving the rest, is keeping an open mind while in the learning stages; continually re-evaluating, and testing for yourself. So when your kite buddies say: Big kite for small wind, small kite for big wind, the bridle goes here, soft sail material is better, the spine dont have to be that straight - whatever; try it out so 'youll' know. One thing for sure, the kite will not lie to you.