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
Canard (aeronautics) homebuilt canard delta design, accordingly named VariViggen and flown in 1972. Rutan then abandoned the delta wing as unsuited to such light aircraft. His next two canard designs, the VariEze and Long-EZ had longer-span swept wings. These designs were not only successful and built in large numbers but were radically different from anything seen before. Rutan's ideas soon spread to other designers. From the 1980s they found favour in the executive market with the appearance of types such as the OMAC Laser 300, Avtek 400 and Beech Starship. Static canard designs can have complex interactions in airflow between the canard