Canard-Roller kite

A Brief History

On December 17, 1903, the Wright brothers made their first powered flight in the biplane "Flyer." Decades later, in 1975, the "Vari Eze," designed by Burt Rutan, took to the skies for the first time. With the further development, the Long EZ, Burt Rutan set numerous records. This aircraft, albeit with a different fuselage, was also built in Germany as the Speed ​​Canard from 1980 onwards. Common to all aircraft types is the canard principle, according to which they were designed and which is said to have particularly high flight performance.

The Canard Principle

"Candles" are aircraft in which the horizontal stabilizer is mounted at the nose of the fuselage, well in front of the wing. The name alludes to the flight pattern of the bird of the same name, which bears a certain resemblance to canard aircraft. Of course, every duck has its tail feathers on its tail, but what gave it its name is the long, outstretched neck that extends far forward in flight. Duck planes have two aerodynamic advantages over conventional planes: firstly, the small canard wing on the head also generates lift (in a conventional design, the horizontal stabilizer at the tail generates downforce), the overall lift area is larger, and secondly, the airflow on the main wing cannot stall in critical flight situations; a duck cannot spin or "skid." The drawback with duck planes is their behavior in slow flight, which can lead to critical situations during a landing approach and has thus prevented them from becoming more widespread. Their small number in the aviation world still makes them seem exotic. However, in all eras of aviation, the aerodynamic advantages of ducks have always been remembered when it comes to flight performance and economic aspects.

Manlifting in Berlin and Bruno Horstenke

In 1913, aerobatics entered the aviation world; the first inverted flight by A. Pégaud and the first loop-the-loop by P. N. Nestjerov caused a sensation. In Berlin, a hang-gliding team made headlines in the press. A team of manlifters lifted the largest Roloplan ever built, with a 15 m wingspan and 90 m² surface area. The pulling forces were difficult to control, so the Roloplan triplane was scaled down to a modest 12 m and 70 m². This allowed two people to be lifted simultaneously. One member of the team was Bruno Horstenke, who later made a name for himself with his own kite designs. The influence of the Steiff Roloplan, which was quite common in his era, is clearly evident in some of his designs. He continued to experiment with kites as model gliders. A carrier kite with a special holding device brought the test kite to altitude, where it was then released. Some kites demonstrated remarkably good gliding characteristics, and Horstenke meticulously recorded their flight times. From today's perspective, I'm thinking of deltas or genkis, for example, which, with a flying line cut at a kite festival, often soar better and farther than their pilots, who have to run after them, would like.

From the "Drachensegler Puck" to the "Hamburger Flieger"

One kite was very successful in these flight tests: the "Drachensegler Puck" from 1921. Its external shape was based on the silhouette of a conventional aircraft. In 1991, Gerd Blattert took it up again, and for the Hamburg Kite Group's winter project, the "Hamburger Flieger" was created. The construction plan has been published several times and has become a popular light-wind kite. Given his enthusiasm for aviation, it's understandable that Horstenke also resorted to a conventional aircraft shape for his "Drachensegler Puck." It would certainly have been surprising if he hadn't also built a model that was a "duck type." But he did build them, the ducks, only they weren't seen on the kite field for a long time, and it wasn't until 1997 when Hans Snoek briefly introduced them again in an article, thus saving them from oblivion. Bruno Horstenke is quoted in the article as saying that the duck models fly just as well as regular kites, but their gliding characteristics are significantly improved compared to earlier models. Horstenke didn't name his ducks, but if you think of them as a counterpart to the "Pucky Duck," how about "Pucky Duck"?

The Canard Roller

Horstenke's duck models immediately caught my attention. I quickly built my first duck with a 2-meter wingspan. However, it wasn't my intention to recreate the original in every detail. The design is based heavily on a Horstenke model, but I discarded the clumsy shape of his canard wing and replaced it with a completely different, more pleasing one. Furthermore, The framework in the area of ​​the struts has been modified, which, for example, causes geometric twist on the canard wing. My affection for the new kite was then put to the test, as the duck was very weak in its wings during its first flights and also very clingy. It responded to minor attempts at takeoff with kamikaze attacks on its creator. It was a good thing that it was quite dark at 11:00 p.m. and no one could see me on my small lawn. But without the right EWD (angle of incidence difference; the measure of the angle at which the wing and horizontal stabilizer are set to each other), not even a canard flies, and it's all just a question of balance anyway. I changed the guy wires, trimmed here and there, looked for a better balance point, and suddenly it flew, the canard that had now completely shed its down coat. With this preparation, I was ready to show off my new protégé on our flying field. There, the duck had to be quite brave and listen to a lot of things, as if it were punishment for its mischief during the moulting season. Even during setup, someone asked if some of the sails were missing between the rods, that I must have run out of fabric... And then the launch: I was holding the kite upside down, a mole kite, it would never fly like that, a Hamburg flyer assembled incorrectly, etc... And it flew after all, and it flew well, and everything was fine (kite psalm). With champagne, the kite was then christened "Canard-Roller." The kite had made its public debut, and I was reminded of Konrad Lorenz and his geese.

I took my little 2m canard to various kite festivals and tested it in everyday kite flying. It soon became apparent that it flies best with a single-point bridle (!) and thrives in a light, steady wind. I immediately remembered the advice that you shouldn't build a "Hamburger Flieger" too small. Well, you build one from 6mm carbon fiber rods, each 165cm long, with a 330cm wingspan. Following this advice, I built a canard roller in exactly that size. However, since its wing depth is almost twice as large as the "Hamburger Flieger," I gave the new canard an 8mm rod. With this rod, the kite is still relatively soft and can therefore be used as a light-wind kite. To prevent the wings and tail from twisting too much against each other, two additional guy wires were added. The single-point bridle, which is still the only leg of the single-point bridle—which isn't exactly common on a flat kite without any tail (!)—can now be easily moved along the long spar using a new, special knot. The knot is immovable under load, but can be moved without tension. Similarities to the Prusik knot or the slip knot are unmistakable. This bridle adjustment allows the canard furler to adapt to different wind strengths. The construction itself is straightforward and in my usual style. The dimensions for the sail can be found in the plan. Fabric allowances for the hem and rod pockets must be added separately; you can use the suggested dimensions or use your own. I reinforced all corners with circular segments with r = 4 cm made from two layers of SpiNy, in the area of ​​the eddy crosses with circular segments with r = 8 cm, and then hemmed the sail with a closed hem of 1 cm. This results in a hem width of 5 mm. The fore and aft poles run in pockets along their entire length, but I omitted them for the sail battens. Cord tabs are sewn onto the end of the sail, which are used to tension it over the protruding cross poles. To find the right length for the cord tabs, you set up the corresponding wing and, with a helping hand, adjust it to the desired tension. The cord tabs are held in place and their correct position marked so that they can then be sewn in place. Some of the guy cords are sewn directly onto the sail or hooked into a split canopy/leaded to the next split canopy. I made all the cords between the mainsail and the canard wing separable with snap hooks, which reduces the risk of tangled cords during setup. The connecting cords are attached to the fore and aft pole with a loop around each of the eddy crosses. All guy cords and connecting cords are adjusted correctly once and then secured. It is essential to ensure symmetrical tensioning and that no waves are introduced into the side of the fore and aft pole. The crossbars are also not supposed to have any sweep; only the longitudinal bar is slightly bent at the end of the action to give the canard wing a more pronounced angle. Furthermore, the word "tensioning" is a bit of an exaggeration given the soft framework; "shaping" is more appropriate.

The Hardware

The frame is built on uncut 165 cm and 82 cm carbon fiber rods. I used FSD brand split caps with side slots. The lower rod on the longitudinal spar supports the sleeve with center stop and, directly behind it, the Exel eddy cross, both of which are glued together on the rod to prevent loss. The sail battens are made of 150 cm long, 6 mm carbon fiber tubing and must be cut to length. The cut-off excess length is used to line all the 8-inch rods in the area of ​​the eddy crosses and the sleeve. If you do this very generously, you will need some other rod scraps.

Bridge Adjustment

With the specified values ​​for the trim cords, the canard furler should be ready to fly immediately. The bridle point is normally one to two hand widths behind the canard wing, depending on the wind. In stronger winds, move it all the way forward, directly to the trailing edge of the wing; in very light winds, move it even further back. On my small 2 m canard furler, the optimal bridle point was a little further back, much closer to the main wing. However, I had also guyed it in a different, incomparable way. Both versions of the canard furler share their wonderful gliding characteristics, which can be used to bridge many a lull in the wind. However, you shouldn't expect much tension on the line.

Indoor Kiting

The canard furler is also ideal for indoor flying. With a fishing rod and some line, it's easy to keep it in the air. The low pulling force, despite the 3.30 m wingspan, prevents the rod from bursting. The single-point bridle is outstanding for indoor kiting, giving the canard furler incredible maneuverability. Using the fishing rod technique, a rotation on the spot around the vertical axis is possible – the single-line Axel! Trick flying with single-line kites – who would have ever thought that possible!

Have fun building it.

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