In aeronautics, canard (French for duck) is an airframe configuration of fixed-wing aircraft in which the tailplane is ahead of the main wing, rather than behind them as in conventional aircraft empennage.
Classes of canards
The canard wing exists in two classes: the control-canard and the lifting-canard.
In the control-canard, most of the weight of the aircraft is carried by the main wing and the canard wing is used primarily for longitudinal control during maneuvering. A control-canard mostly operates at zero angle of attack. Combat aircraft that have the canard configuration typically have a control-canard. In combat aircraft, the canard is usually driven by a computerized flight control system.
One benefit obtainable from a control-canard is avoidance of pitch-up. An all-moving canard capable of a significant nose-down deflection will protect against pitch-up. As a result, the aspect ratio and wing-sweep of the main wing can be optimized without having to guard against pitchup.
In the lifting-canard, the weight of the aircraft is always shared between the main wing and the canard wing. A lifting-canard generates an upload, in contrast to a conventional aft-tail which mostly generates a download that must be counteracted by extra lift on the main wing. The lifting-canard configuration is therefore more efficient than a conventional aft-tail from the perspective of induced drag. The lift generated by the canard wing is significant, so in order to minimise induced drag on the canard, it is usually of higher aspect ratio and greater airfoil camber than a control-canard.
With a lifting-canard, the main wing must be located further aft of the center of gravity range than with a conventional aft tail, and this increases the pitching moment caused by trailing-edge flaps. Aircraft with lifting canards cannot readily be designed with sophisticated trailing-edge flaps.
Examples of canard aircraft
Aircraft that have employed this configuration include:
Published - July 2009
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