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Now that you have read how the various parameters cause a stunt kite to behave it is time to design a kite. Step 1 is the most difficult. It is here that you must decide what characteristics you want the kite to have. Keep in mind you cannot have everything and that a good kite design is nothing more than making the right trade offs between conflicting requirements and their controlling parameters. For this design example I am going to design a light wind kite that is larger than normal. I always start with the frame, so I am going to consult the spar chart to pick a spar size and to finally size the kite. Spar Chart
Since this is going to be a light wind kite (not an ultralight) I will use as my reference a 64.5 inch leading edge kite framed with 0.250/2 wrap graphite spars (this is the configuration of most lightwind stunt kites). From the chart I selected 3 different spar sizes. Number one is a 0.280/3 wrap from Clearwater. If the reference is a 0.250/2 wrap the scale factor for the reference is 0.880. If I divide the scale factor for a 0.280/3 wrap which is 1.078 by the scale factor of the reference which is 0.880 I get the scale factor for the new kite of 1.225. Multiplying 1.225 times the reference of 64.5 inches I get 79 inches for the new leading edge length. If I do similar calculations for a pultrude AFC 2540 spar I get a new leading edge length of 78 inches. For a Clearwater 0.315/3 wrap I get a leading edge length of 86 inches. I am going to use the Clearwater 280/3 wrap for my kite but you may choose your own and can just scale the dimensions I ultimately come up with.
Next let us settle on the nose angle for this new design. A nose angle of 90 degrees will give the most sail area for a given leading edge length, however for my taste I like the looks of a wider nose. A larger nose angle will make the kite turn easier. This is a trade off of looks, ease of turning on the plus side vs higher wing loading and poorer tracking on the minus side. The larger angle will also reduce tip vortex drag, the primary source of drag at the low velocity this kite will fly. I am choosing an angle of 109 degrees for the nose. I am looking for ease of turning and looks, I will recover some of the tracking capability with a deep sail (large close up angle) and some of the sail area loss with large wing tips. Think about these choices. You may want to try something different. If you use pointed wing tips then you may want a smaller nose angle so as not to lose much sail area and maybe a less deep sail since tracking was not compromised as much.
Now let us choose close up angle or sail depth. My choice for this kite is 20 degrees. This is toward the upper end you will see on any stunt kite, but I like a deep sail not only for the tracking but for more solid edge performance. Another advantage of the large sail billow is that it will reduce the compression loads on the spreaders. Since the lower spreaders are quite long on this design the lower compression loads help quite a bit. This much sail depth will slow the kite somewhat, but it is a large kite meant to be flown in light wind and will be slow in any case so a few percent will not be much absolute speed reduction. Keep in mind this is only the first try at this design and to get everything optimised on this first try would be a miracle. But keep track of the parameters and after flying the kite try to figure out what changes would improve the design.
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