Circoflex Construction Notes

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I just finished the new 12 meter (circumference) circoflex ring with a ripstop leading edge and mylar (silver) body. The reason for the ripstop is to essentually provide a tough wear resistant leading edge and spar pocket.

As I asked on the rec.kites newsgroup for help in figuring out how to attach the ripstop to mylar, I return my results to the world kiting community.

As such this is a report of my construction notes so that others may benifit.

[photo] This is not a complete plan for circoflex kites, but additional information for those who are wanting to build one, or a better version of this wonderful kite. These notes are built around the construction of a 12 meter circumference silver mylar circoflex, with a number of inavations to the standard circoflex plan, (See Circoflex Page Above).

The ripstop leading edge was created from a black strip of 3/4oz ripstop, 5cm wide and 12 meters (pieced together with diagonal stiching). The strip was folded in half and sewn down the middle to form the spar pocket.

The body was as for a normal circoflex, 12 meters in length directly from a roll of aluminised 40 micron thick mylar (saturated polyproplene sheeting) and double sided taped end-to-end to form the main ring. I do not trim this mylar width wise, but just use the roll, at this width, regardless of the final circoflex size.

The loose edges of the ripstop spar pockect was then attached with doudle-sided tape on both sides of the mylar body, and the leech line pocket created by folding the trailing edge over the line and securing with more double sided tape.

     ripstop              mylar body                  leech line pocket
    .----v-----                                            __----.
    | OO | ------------------------------------------------------'
      |  |  |
      |  |  `-- double sided tape here (both sides of mylar, inside ripstop)
      |  `-- stich sealing spar pocket
      `-- spar X2
To let the spars be inserted and removed a velcro flap is added in a 30cm section of the ripstop spar pocket. Velcro on the mylar side is stuck down with a glue backing, while the ripstop side of the flap is sewn on.

[photo] An alturnative spar sleeve constructions was offered by Leong Ceewan <ceewan@pc.jaring.my> in the form of a Double Sleeve which may work even better.

The spar however is doubled, with two round carbon fibre rods (3mm) taped together with staggered ferules (brass tubing). This forms 8 x 1.6 meter spars from 16 x 1.5 meter lengths of 3mm carbon fibre rods.

The spars overlap each other by 5 cm to form the leading edge hoop spar, 12 meters long. Each spar has a ferule on the inside end of each of the two staggered rods to allow them to join together in either direction. In fact by overlaping the double spar in this way the ferules do not need to be very strong to maintain a smooth curve of the ring.

      |<----------------1.5m-------------------->|    |<--5cm overlap
This double spar, wants to bend narurally into a hoop in only one plane of movement, and resists being pushed sideways by the wind. This helps to stop the circoflex collapsing into a heap, especially due to wind turbulence.

Ripstop loops 1 meter apart around the spar pockets allow the attachments bridle lines (See my Circoflex Hints and Tips for measurements).

For the ballist weight, bolt washers from the local hardware (7 of them initially, increased later to 11 washers) was taped with wide clear boxing tape in the usual spot, 15 cm in from the trailing edge spread out between the 5 to 7 o'clock marks.

And as a final step the leach line was pulled 20cm shorter and the mylar puckering spread as evenly as possible around the ring. NOTE the shorter the better! Shortening it too much will produce far too much drag. It shoudl be only just short enough to form a slight lip in the final kite to stop flapping. It does not need to be much at all.

[photo] Well that is it. On the field a few helpers and weights was used to hold the loose mylar ring down in the wind while the spars were feruled together and inserted through the velcro opening and around the ring. After that the spars own weight holds the kite down until it was ready for launched.

The kite flew brilliently first time though it was evident from the roll of the kite in both directions that more ballist weight was required. After the additional washers were added, the kite was raised to a 60 meter height. Comments from people told me that they saw this kite 3 to 4 km away and came to investigate.

[photo] This kite I can honestly say is my best circoflex yet.

Mail me if you have any queries, clarifications, or just want to express your experences with circoflexi.

Created: 4 May 1998
Updated: 18 May 1998
Author: Anthony Thyssen, <A.Thyssen@griffith.edu.au>