Cul de canard Cul de canard Cul de canard (CDC) (French for "duck bottom") are the feathers from the back of a duck directly around the preen gland (uropygial gland); they are very buoyant due to preen oil produced by the preen gland. They are used when tying dry flies for fly fishing. They owe their buoyancy to their proximity to the ducks preen gland which secretes an oil distributed by the duck as a cleaning and waterproofing measure. It is unnecessary for the angler to add additional oil by way of floatant. Flies incorporating CDC are easy to dress requiring no floatant
Aviafiber Canard 2FL the main lifting surfaces were supported atop tall, V-shaped pylons which both generated lift and acted as vertical fins. Wings, pylons and canard have Wortmann FX-67-170 airfoil section. A further development of the concept can be seen in the Canard Aviation Canard SC, the production version of the 2FL. During flight tests of the SC, from 23 July 1983, progress was accelerated by the use of an auxiliary König SC 430 3-cyl. two-stroke radial engine mounted on a pylon between the V-struts and main-plane, driving a folding propeller. Results of flight testing with the engine running encouraged Farner and Bucher