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Interesting circular and rotary kite designs.

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This is a simple circoflex kite made from a standard kitchen garbage bag. I call it a Circoflex GB. Find instructions here.
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Rotary kite experiments -

Kite 1- Nice, but very heavy with wood ends and ball bearings. This required too much wind.
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Kite 2- A remarkable improvement. The wooden rod goes all the way through the kite for strength. It died when the wood swelled up with water and eventually fatigued and broke about 4 inches into the Styrofoam. This kite steers exactly like any two line kite and is extremely maneuverable.

It is made from 1" thick high density Styrofoam. It weighs in at about 3.5 oz. and works best in steady wind over about 8-10 MPH. The center 1/4" wooden rod has been replaced by a hollow carbon fiber arrow shaft. This brought the weight up to 3.75 oz.

The leading edges are covered with clear packing tape to reduce chips obtained by the necessary kick to get it spinning. Nails and plastic electrical bundle tie-wraps make excellent bearings, especially when a little Vaseline is added to the nails. Eventually the bending of this kite in high winds generated stress fractures in the center of the kite. The fractures have been contiually filled by squirting Gorilla glue into the crack and covering them with clear packing tape. This type of repair can be repeated many times before a new wing must be manufactured significantly increasing the life of the kite.
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Kite 3- This kite is a thing of beauty which requires 19 MPH air to fly. First flight damaged one of the end shafts which only extend through the first two internal chords. Eventually thin foam rings were added on the ends to protect this delicate tubular kite. They also store additional rotational energy to keep the kite from being stuck in mid rotation. It steers in reverse to a normal 2 line kite making it tricky to fly. Manufactured from balsa wood with a Monokote covering.
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Kite 4- This was an attempt at an improvement to #2. It flew terribly, due to vanes 1&4, 2&5, 3&6 producing successive lift. Ends oscillated up and down as the lift pulses arrived at certain wind speeds. It steers in reverse to a normal 2 line kite. Changes in direction rapidly decelerate the spin. Air flow over the blades at extremes of the wind angles is poor.
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Kite 5- This was an attempt to fix the oscillation seen in #4. This worked, but all the other detrimental flying characteristics of #4 remained.
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Kite 6- This was an attempt to fix #5. The hope was that adding the baffles would improve laminar air flow and possibly return the kite to conventional 2 line kite steering as was seen in model #2. One strange feature is that this kite can be pulled along the grass and will actually launch into the air. Steering response was very poor compared to the highly responsive #2.
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Kite 7- Constructed from 2 liter bottles and foam. Very strong and light. The hope being it will produce more lift and fly at lower airspeeds than #3. At 5oz this kite is too heavy and could be made much lighter with thinner bulkheads and less glue. Gorilla glue was used to connect the bottles and insert the shaping bulkheads. Designing the bulkheads for the 4.3 inch circumference 2-liter bottles was non-trivial. The next model will probably use Monokote to save weight and make construction easier.
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Kite 8- Constructed from the safety cover used for florescent lights. It flew, but bent and once bent refused to spin. If there was a way to make it stiff enough from end-to-end it would have been successful. It was very difficult to transport in my little car. Lesson here is that any bend in the kite will stop the spinning action. A rotary kite must remain rigid under any wind condition.
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Kite 9- Constructed from balsa ribs with longerons. Covered with Monokote from the local hobby store. This flew very well, but eventually it got dunked in the lake a few times. It was quickly assembled with Elmer's glue, not waterproof Gorilla glue as is my normal building glue. The balsa soaked up water, the glue failed and it blew up. The center damaged section was removed and it was reused, the repair was repeated a week later, and eventually this drastically shortened kite had insufficient lift and was retired. It made the eeriest hollow noise as it flew. Cold Monokote punctures easily letting water into the structure. I really liked this kite, but will make it a few inches shorter next time to fit easily into my car trunk and use waterproof glue. The white section was 36" long.
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Kite 10- Constructed from 24 ounce aluminum cans. This was a dismal failure. It was designed overnight when 50 MPH winds were predicted. It did fly, but was not particularly stable. It is very light, strong, and might be a useful design with the exception that aluminum skinned wings dented very easily. I might again experiment with aluminum cans, but foam is still the best and most durable construction material.
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Kite 11- Constructed from the remnants of kite #10, some wood arrow shafts, and some acrylic fabric. This kite flew fairly well, but exhibited the properties of not enough lift. The jury is still out on this kite. Making the fabric wasn't easy as it had to be tight and held stretched from ring to ring. Slots inside the fabric exist for both wooden leading edges and the center carbon fiber arrow shaft. I think the airfoil generated by two wooden rods being the leading and trailing edges isn't particularly good and generates some drag. My hope was that the cloth would last longer than aluminum, monokote, or foam skins. Perhaps if a single tube of fabric was used it would be easier to make and produce a better airfoil.
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Kite 12- Constructed like kite #2, but use a carbon fiber arrow shaft. Bevel the foam edge at 45 degrees, but not so much as to create a sharp edge that will chip off. Cut wing down the center, scoop out slot for arrow shaft, glue wing halves together with Gorilla glue. Cover seam with clear packing tape. Glue on end disks. Insert wood plugs into the arrow shaft until entirely inside arrow shaft, no wood extending. Drill a centered hole for the nail. Use a nail with a large flat head. File the inside of the nail head (remove ridges from head stamping operation) so a fishing swivel will spin well. Insert nail into a drilled hole with Gorilla glue. I like disks that are about 7.5" diameter made from 1/4" blue foam, commonly used under house siding. I like the wing to be about 7" wide and as long as your arrow shaft will support and allow the shafts to stick out half the disk diameter. Don't forget to lubricate the nails with Vaseline. Thicker foam can be used for end rings. To reduce drag, you can bevel the edges at 45 degrees. If you bevel to a point the edge tends break off, so again taper to an edge that is about 1/4" thick. Included in the photo is my favorite 2-line kite reel. It is made from Luan subflooring with a couple of coats of varnish. It has almost 125 yards of 50# "spiderline" fishing line purchased from Walmart. Good stuff without much stretch. At 3.5 cents/foot it would have been nice to get the entire 125 yards. They shorted me 35 yards in the reel I purchased, making me wonder how many fishermen know these reels are shorted 28% from the lengths advertised. A final improvement might be to cover the foam with a skin to stiffen the airfoil and resist the inevitable stress fractures that develop in high winds.
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