Lifted from rec.kites Google Group (original post by Bernhard Malle can be found
>>here<<.
User information for C-Quad four line traction kites
Design, shape and history: Their basic layout is "C"-shaped with a small
diameter fiber reinforced plastic (fibreglass or carbon) rod holding the
curve of the "C" which is the leading edge and from one to 6 or more similar
rods arranged as spines to provide some form to the skin and trailing edge.
These kites are neither soft kites nor framed kites but are of an entirely
new hybrid arrangement using single skins with flexible f.r.p.(fibre
reinforced plastic) stiffeners. Developed to be suitable for re-launching
from water (hence the single skin and minmal structure) for use with our new
monohull kitesailing boat (the KiteBoard) and the FoilBoard, our new "snow
board for the water", these kites are proving to be very competitive by
performance and price for buggying and other traction kite uses.
Other sizes, up to 6.3sqm, are now being developed and already being used by a
selected group of testers in buggy-racing and kite-boarding.
Rip-stop nylon (Toray "Chikara") is used for all C-quads.
Performance:
The shaped skins and multiple bridle lines to the leading edge and spine rods
create curved airfoil shapes which give good L/D (lift to drag ratio- the
determinant of upwind performance) and excellent lift coefficients (the
measure of power for size). These kites are powerful and easy to use with
performance matching and bettering the very best traction kites in the
world.
Rod Stiffness: as frame material. We are testing
Currently C Quads are supplied with fiberglass rods or hybrid rod of 25%
carbon in the leading edge which provides excellent performance in the air
(more power and easier flying in light winds) but it does require more care
when packing the kite in its bag because the carbon is more brittle and
could break when the kite is packed wrong!) Generally our experience is that
there are few valid requirements in traction kiting for pull of much above
the fliers body weight hence rod diameters are set for each kite size so
that compressive distortions don't occur until the pull is greater than
about 100kgms. Larger diameter stiffer rods can be fitted during the
manufacture or at any later stage. Small increases in rod diameter result in
gains in stiffness but there is still significant weight and packing
disadvantages to doing this.
C-Quad Tuning:
As with other forms of four line kite, the main tuning is to set the
relative brake line lengths to suit the wind and your flying style. Although
we have experimented with many rigging systems, in their current form
C-Quads have only the brake lines (no main bridling) to the trailing edges.
This results in some flapping in light winds when the brakes are let fully
off but facilitates maximum power control and als, at this stage of
development, appears to be the most luff resistant arrangement.
C-Quad Flying:
Some over steering can occur coming out of stalls but handling is generally
highly acceptable. When introducing new users to C-Quads, shortening the
brake lines by a 100mm or so facilitates quicker adaption but experienced
C-Quad users are now adopting a very different flying style than for
conventional ram-air 4 line traction kites. The developing technique is to
set the relative brake line length such that the handles are gripped little
below the main lines rather than at the main lines with one finger above as
is usual for conventional 4 line traction kites. A "Neutral" wrist position
then sets the kite for maximum power while pulling on the brakes stalls the
C-Quad as for conventional flying but releasing the brake lines a little
de-powers the kite (without losing L/D but requiring some vigilance against
luffing). It is this last technique, which conventional 4 line traction
kites can't accept without collapsing, that is probably the main reason for
their starting performance in buggy racing and on the water. New users tend
to oversteer C-Quads by applying too much "2 Line" control and insufficient
"brake" steering. In extreme cases this can cause collapsing.
Design Protection:
Peter Lynn Ltd. employs two graduate engineers plus support staff full time
for traction kite product development and is only able to cover the cost of
this if the breakthroughs we do make are not immediately copied by others
freeloading on our work. Fortunately we have been able to file for a
comprehensive patent to protect the C-Wing and the C-Quad designs and will
vigorously pursue copiers. The patent covers not only specific aspects but
also the combination of features we have used. Kite graphics are protected
by copyright.
Water re-launching:
Being single skin, C-Quads do not hold water so have a natural advantage
over ram air traction kites in their re-launch ability.
In 1999 we expect to be offering special C-Quads with molded foam pads
fitted to the wing tip leading edges to further facilitate water
re-launching. For standard C-Quads flotation can be retro-fitted by sticking
pieces of 5mm to 8mm thick polyethylene foam (eg, from Hiker Pads") to the wing tip
leading edge areas using double sided tape. The more flotation that is added
the easier water re-launching becomes but if more than approx. 0.3kgm of
foam is added to the 4.2 C-Quad, light wind handling deteriorates,
proportionally for other sizes.
Water re-launching is easiest in stronger winds and is facilitated by wave
action but is not possible unless at least one of the kite's flying lines is
tight.
Handlebars.
Normally C-Quads are flown with the usual 4-line kite handles (not included
in the kite package). Contrary to our previous beliefs it has proved to be
possible to make a bar, of cunning shape, but without swivels or pivots,
that permits the full range of 4 line kite control. Comprimising a short
central straight section that bends down and then out at reach end, in
conjunction with a hip harness, these allow very easy one hand flying. -
especially useful when a spare hand (or even two for short times) is
required while getting back on the boat or refitting FoilBoard footstraps
etc.. Handlebars do take a little time to adapt but then offer C-Quad
control which can be more reliable than by individual handles in many
circumstances. These bars will become available in 1999.
C-Quad are copyrighted names and registered trade marks for Peter Lynn Ltd
Traction kite products. All rights reserved. Patent filing number: 330489.
ATB,
Sam
P.S. There are supposed to be two other info sheets, but thus far all references lead to links to defunct websites or file hosting services that were
never properly processed by Archive.org (The Way Back Machine).
"I never had any friends later on like the ones I had when I was 12 - Jesus, does anyone?" - The Body by Stephen King
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