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) NASA has also investigated a one-piece slewed equivalent called the conformably stowable canard, where as the surface is stowed one side sweeps backwards and the other forwards. The Rockwell B-1 Lancer has small canard vanes or fins on either side of the forward fuselage. They form part of an active damping system that reduces aerodynamic buffeting during high-speed, low altitude flight. Such buffeting would otherwise cause crew fatigue and reduce airframe life during prolonged flights. Canard aircraft can potentially have poor stealth characteristics because they present large, angular surfaces that tend to reflect radar signals forwards. The Eurofighter Typhoon uses