Original Circoflex Kite Plan

Prolog - a bit of history about the english circoflex plan.

This plan was first recieved, htmlized, and placed on the internet on 15 May 1997. It is direct copy of the plan as written by Tom Oostveen, one of the co-inventors of the Circoflex.

Unfortunatly about a month latter (27 June 1997), I recieved an email from Tom Oostveen, who requested that the plan be removed from the internet for the moment until he can review it. I did this moving the plan to a secret URL and emailing this URL to anyone who formally requests the link from me by email.

Since then Tom never returned my emails, or anyone elses. After attempts over a full year by Peter Peters in the Netherlands, further contact with Tom has been recieved.

Requests for the then secret URL for the english version of the plan have been regualar (4-5 each week) during this period.

Finally both Peter Peters and myself agree, enough is enough! The French Version has been available since the plan was first published in european kite flying magazines. Also a simple and cryptic version has also been printed in a second edition of {...insert book name here...}.

As such it is only right that an english internet version be made available. So on 27 of November 1998, after more than a year of being offline, the plan is again available. and you see it before you.

For more information of this and other circoflex kites please, have a look at my Circoflex Kite Information Pages

-- Anthony Thyssen

What is a Circoflex

The Circoflex is a ring shaped kite that consists of a strip off fabric 750 x 50 cm. ( or 1000 x 60 cm), a seam of 2 cm at front containing only the construction material, a reinforced fiber ring of 750 cm (or 1000 cm) 3 or 3.6 mm and a seam at the back containing a 2mm line to ply the fabric into a curve that increases the wind pressure in the construction. The Circoflex has 12 bridles that join in groups of 7 and 5, interconnected with a string to adjust the flight angle.

Reactions to the Circoflex

Lots of remarks and Questions during the experimental lifting sessions and the first official lift in Dieppe shows that the shape of the Circoflex object, stimulates creative thinking

[photo]

A natural scientist passing by: "Sir, this object really starry me thinking, I don't understand the principal yet".
"How does it fly, where are the spars"?
"Does it pull? Oh, no, it's just like a delta. "
"To my opinion it's a revolution in kite design ".
"The sled kite, was because of it's simplicity the kite of the seventies.. I suppose this will be the kite of the year 2000".
"Nice kite, what a pity I didn't invent it myself".
"Could you also join the rings or fly different kites or different sizes on one line".
"it seems you are fully addicted to rings. "Lord of the Rings" translated in Dutch means 'addicted to rings',
"it's that simple, I don't understand why it wasn't invented before".
"Could it be built with carbon fibre?"
"Could it be made like a spinning wheel or like a turbine with a propeller inside ".
"Ah, well you just should be struck by the idea ".
"What is it? It's no kite, I can see no string. It's not a balloon either, it can't be a UFO because it is fully open".
"It's no kite, its just an object of art". .
"I have never seen something remarkable like this before!"
"How is it possible that this one fibre ring construction flies ? "
"Is it possible to fly it without the fibre ring ? "

Experimental Circoflex

How to fly a windsock as a kite. In 1993 we had to fly a windsock but we had a lot of trouble lifting the kite Which we had to fly over a huge river standing on a breakwater. This motivated us to experiment, in order to fly the windsock independently as a kite. This windsock was not constructed traditionally as a conus, which provides too much drag and too little lift, but like a tube with a 6 metre circumference, 7 meter long, with a fibre rod in the entrance and with a rope in the seam at the end of the tube. This rope was pulled about 30 cm shorter than the 6 metres at the entrance.

In order to test the influence of circumference and length on flight characteristics an 8 metre circumference tube 4.5 metres long was constructed in spinnaker nylon. This turned out to fly even better titan the long tube. This was the start of the challenge to experiment with variation of length and circumference. We initially developed a Circoflex 750 and Circoflex 1000 (750 and 1000 cm) circumference version.

The experimental versions of the Circoflex were made out of taped high density plastic or Mylar The twelve point bridle was just towed around the fibre not to the fabric, this spreads the pressure on the surface of the material. The first step in shortening the 4,5 m length version became 1.50 cm, the next Circoflex experimental versions were 1.20; 1.00 and 0.80; and finally 0.60 metres. A balanced aesthetic relation between circumference and length turns out to be 50-55cm for the Circoflex 750/50. But we even flew a Circoflex 750/35 cm version which also flies in low stable sea-winds, but the proportion of length and diameter is less balanced in our opinion. The Circoflex 1000/60 is best with 60cm length.

Construction:

The only construction needed is a ring of fibre or reinforced fiber which can be folded for transport into 4 small rings, together with the fabric ready to fly when it unfolds in a second (1000cm into 4 rings or 250cm circumference, diameter about 80cm). For more than 4 to 5 Beaufort winds or when scaling up the size, carbon fiber could be applied. At the end of the ring is another 'construction' existing of 2mm nylon line in the seam of 2-2.5cm. This line brings about the effect of a curve causing the air pressure in the construction to maintain the ring shape. It should be about 20-25cm less in circumference than the fiber ring.

One important feature: a weight of about 35gr should be taped or taped by Velcro. The weight should be spread evenly over 30-35cm inside the bottom of rite kite in the middle of the hours 5 to 7, some 8 to 10cm before the end seam. As a weight, balls of lead, used in the seams of curtains should be fastened to the sail. Instead of the lead balls, a zipper could be stitched at the bottom. This functions not only as a weight but as a device to build up the Circoflex easily.

When using nylon, the fiber ring can also be taken out the construction for transport. Stitch a ring on both sides of the zipper on front seam. Spread out the nylon, put a tent pole through each of these rings and the fibers can easily be put into the seam, This is even more important with an upsized Circoflex when using carbon fiber

Bridles

The bridles should be connected to nylon tape stitched directly to the seam before stitching the seam itself. The rings should be pointing to the center of the fiber ring. When the seam is too wide the bridles pulling on the fabric via the tapes and on the rings will cause a smaller ring in the front (a kind funnel shape) which disturbs the flying characteristics. When the lines in case of Mylar and high density plastic will be knotted directly to the fiber ring, the seam should also be rather small. Via the openings in the fabric where the bridle lines are knotted an air flow may pass and blow up the seam with the same consequences for the flight characteristics. When the lines are connected directly to the fiber, an extra check is needed after unfolding the four wise fold Circoflex. While folding, the fibers turn, and the lines will turn too and may become shorter..

The 12 bridle points are evenly spread over the fiber ring like on a clock. It is also easier to communicate when the ring is not fully in a circle share and some Adjustments need to be made, The bridles of 9,10,11,12,1,2,3, should be connected to one ring. The bridles of 4,5,6,7,8, should be knotted to another ring. In between these rings a line 20-25cm will be connected in order to adjust the third ring to which the kite line is fastened. The length of the lines are in the table. As a rule of thumb: when the kite has the tendency to turn to the left the bridle at the opposite should be repositioned. The ring Should have an ideal round circle shape.

Fabrics

Because of the evenly spread pressure on the ring surface and the taping of the seam around the fiber ring, light material like high density plastic and Mylar can be applied. Other fabrics like tyvek, nylon, ripstop nylon and polyester can be used.

Experimenting is going on to apply fabrics that let some wind pressure pass in high winds.

Patterns and special designs

The simple Mylar silver/gold version is so appealing to people that they don't understand what is up there. Even more when flown with very thin bridles and line. As in all kites large patterns and not too many different colors will emphasize it's shape.

Esherpatterns, Mondriaan, Indian and African .simple patterns can inspire the constructor. Special Circoflex kites have seen constructed for night flight. A black version with over 30 LED's with 9 programs, the other also black with silver .Mylar and over 100 reflecting tape streamers at the end.

Further experimentation

The Circoflex can be upscaled. We are constructing a 20 and a 36 meter version.
The Circoflex can be put in trains by connecting the bridle ring of first kite with a line of about three metres to the bridle ring of the second kite.
A smaller ring could be constructed inside the larger ring by connecting the smaller kite to the 12 extra lines connected to the center of the biggest kite.
Rings could be interconnected and flown with multiple bridle lines.
With a carbon fiber ring a construction like a bicycle spoke system could be made. One the axle, turning objects could be added.

You can...: Back to Circoflex Information Pages.

Recieve Date: 9 May 1997
Html Created: 15 May 1997
Plan returned: 27 November 1998
Original Author: Helmut Schiefer
Co-inventor: Ton Oostven
Html Conversion: Anthony Thyssen <anthony@cit.gu.edu.au>