Circoflex kite/ last updated Oct 13, '99
Come back often to get tips and tidbits from people who are building these kites today!
Send us digital (or digitized) photos of your masterpiece Circo, and we will start a page of kites made from these plans! Gary Engvall; firstname.lastname@example.org
Notes from AKA workshop, Oct 8, '99:
Ed Spencer mentioned that people experience problems with brass ferrules breaking. Putting a flat taper on the ends of the rods spreads the stress, and the bending stress is born by the taper instead of the ferrule. Remember that this will reduce the length of the stick by the length of the taper.
3 yards of 41" ¾ ounce ripstop nylon. (1/2 yard per panel)
Five 48-inch pieces of 1/8" pultruded Fiberglass rod.
Five 1/8" i.d. brass ferrules.
71 feet of 50 pound dacron line.
6 curtain weights (lead square in fabric or plastic cover, approx. 1"x1"x1/16")
Note: The curtain weights should add up to about 3 ounces. Some weights are smaller. Weights we bought on the west coast were half the weight, took 12 weights for proper ballast. Your mileage may vary. Check your weights with a scale. Use whatever number add up to about 3 ounces, and space them evenly between 5 o'clock & 7 o'clock.
Another weight note: It has been pointed out that curtain weights can be expensive ($1.49 for four of them) and the same effect can be achieved with nickels (or other suitable coins...)
Why a 20 foot Circoflex? It makes the best use of the cheapest (by the yard) fabric. It can be framed with either 6 pieces of 40" carbon, or 5 pieces of 48" fiberglass. Can be made from a single piece of 54 inch fabric, 6'9" long, cut into 3 pieces 18" wide.
Fabric: Cut 6 pieces, 18" x 41" Make sure the ends are square. 41" allows for a ½ inch seam allowance. The fabric may not be exactly 41" inches long. Panels too long can be cut down, short ones can be alloed for in the seams. The seams need to be 40" apart or the circumference will not be correct. Sew all 6 panels together, making one long panel 18" wide and 20 feet, 1 inch long. On the good (finished) side, draw lines for the sleeves 1" in from both edges and the entire length of the panel. Crease along these lines. After the lines are marked and creased, sew the ends of the panel together. After the ends are joined, fold on the line, and sew the sleeves closed, all the way around.
Note: These plans call for 'slits' to be cut into the leading edge sleeve. This is easy, and optional. If it is desired to make the leading edge stick easy to remove, then sew an extra row of stitches 3/8" back from the leading edge fold. This makes a sleeve big enough for the 1/8" stick and the external ferrules. Tabs can be sewn in place of the slits. Be careful not to sew thru the sleeve for the leading edge stick.
Fold the sail to find the 12 & 6 o'clock points. Measure to find the bridle points in between, Cut a slit halfway into the sleeve at every "hour" on the kite. Cut one slit in the rear sleeve at 6 o'clock.
Sew the curtain weights evenly spaced between 5 & 7 o'clock, about 2" towards the front of the kite from the back sleeve. The sew tab for the weights should be towards the front (bridle, spar) of the kite. Hint: 6 weights = 5 spaces = 8 inches on center, for a 20 foot sail.) For the smaller weights that required 12 weights, we put them on 4 inch centers, and 'doubled up', put them right next to each other, in the middle.
Make a tension line by tying an overhand loop and then putting a mark in the line 233-3/8" from the end of the loop. Cut it about 5 inches longer. Thread it thru the rear sleeve by Lark's'ing it to a fid (6 inch long ¼ inch dowel with a hole cross-drilled in it.) Pull out the loose end, thread it thru the loop, pull to mark, and tie off. Pull all excess back into sleeve.
Sticks: Glue a ferrule halfway on each stick (push the stick into the ferrule so that the ferrule is half on, half off) and put aside to dry while you make the bridle.
First make one each of the 12 o'clock and 6 o'clock bridles: The 12 o'clock has a finished dimension of 55". Cut a line 65-3/4 inches long, put a mark 5" in from each end, bend at the mark, and tie and overhand loop. If the string is bent right at the mark, the finished string will be 55" long.
The 6 o'clock has a finished length of 18.5. Cut a string 29-1/4 inches long. Mark 5" in from each end, and tie overhand loops.
Bridle table: Finished length: Cut:
12 o'clock 55 65.75
1 & 11 o'clock 53.5 64.25
2 & 10 o'clock 49 59.75
3 & 9 o'clock 42.5 53.25
4 & 8 o'clock 34.5 45.25
5 & 7 o'clock 24 34.75
6 o'clock 18.5 29.25
Secondary Bridle: 6.04 16
Rear tension line: 233.375
Finished depth of kite, after sleeves are sewn: 16 inches.
Note: The relationship of bridle to kite is linear. These values are scalable. For a kite twice the size, double these values. This factor should be applied to the bridle, the circunference, the depth, the amount of weight, and the thickness of the leading edge spar.
Framing and finishing the kite: After the sail is sewn, the ferrules are glued and dried, and the bridle is tied, it is time to put in the sticks and install the bridle. Fiberglass & carbon spars have been known to have splinters that enter fingers, so it is a good idea to wear gloves for this part.
Note: The Bridle Table does not allow for Lark's Heads around the leading edge spar. If Lark's Head knots are to be used, add 3/4" to the Finished Length dimensions. No change in bridle length needs to be made if using the 'extra' sleeve and tabs.
Note: If using the 'extra' sleeve and tabs, it can be difficult to persuade the stick to go thru the sleeve. Putting a vinyl end cap over the end of the stick makes it much easier. Also, if using tabs, it is easiest to tie the kite end of each bridle leg to the kite first, using an Overhand Knot, then tying the Overhand in the other end of the bridle leg.
Start at 12 o'clock (The "top" of the kite) and insert stick into the sleeve with the 12 slits in it. Push to 1 o'clock, and put one end of the 1 o'clock bridle leg over the stick. Push the stick further in to the 2 o'clock position and put one end of the 2 o'clock bridle leg over the stick. Do this all the way around the sail. When you get back to 12 o'clock , put on the 12 o'clock bridle and push the end of the last stick into the empty ferrule of the last stick. There should now be a bridle leg at every "hour" of the kite.
Take the Secondary Bridle, which is a string 16" long and marked 5" in from each end. Thread one end thru the 6 o'clock, then the 5 & 7 o'clock, then the 4 & 8 o'clock bridle legs. Adjust so the mark on the Secondary Bridle is just showing away from the loops, and tie closed with several half hitches.
Take the other end of the Secondary Bridle and thread it thru first the 12 o'clock bridle leg, then the 1 & 11 o'clock, then the 2 & 10 o'clock, then the 3 & 9 o'clock. Adjust so the mark on the Secondary Bridle is just showing away from the loops, and tie closed with several half hitches.
Last thing: Make a knotted loop by taking 12" of string and tying it closed with an Overhand Knot. Lark's Head (actually, a Prussik Knot is better to use if you know how to tie it) it to the Secondary Bridle. I fly mine close to the bottom.
Lark's Head: http://www.netg.se/~jan/knopar/english/larkhuvu.htm
Prussik Knot: http://brmrg.med.virginia.edu/knots/prussik.html
Original kite design by Ton Oostveen. Picture by Ton Oostveen. Dimensions are adapted from a table by Mike Dallmer. Original drawing may be viewed at http://www.sct.gu.edu.au/~anthony/kites/circoflex/original/fig1.jpg.
Anthony Thyssen's Circoflex web site: http://www.sct.gu.edu.au/~anthony/kites/circoflex/