A canard is a small wing mounted forward of the main wing. This horizontal control surface may replace or augment a conventional horizontal stabilizer. Incorporated into an aircraft design, the canard configuration is intended to modify airflow over the main wing, providing pitch control, longitudinal stability, and additional lift. Because the canard is designed to stall before the main wing, it prevents the main wing from reaching its stall angle, helping delay the onset of stall and preserving control at high angles of attack.
Expert behind this article
Jim Goodrich
Jim Goodrich is a pilot, aviation expert and founder of Tsunami Air.
What is a canard airplane?
A canard airplane is an airplane with horizontal stabilizing and control surfaces in front of supporting surfaces, which is a wing configuration where a canard is placed forward of the main wing. In the lifting-canard configuration, the weight of the aircraft is shared between the wing and the canard.
In aviation, a canard means both the small forewing mounted part of the main wing and the entire airplane built around this layout. The term ‘canard’ is the French word for duck. Observers of the 1906 Santos-Dumont 14-bis thought the machine, with its forward surface stretched ahead of the wing, looked like a duck extending its neck in flight, and the name stuck.
The canard design places a horizontal control surface - alternatively called a foreplane, a forward control surface, or a small wing - ahead of the center of gravity and ahead of the principal wing. Because this surface provides lift as well as pitch control, the configuration represents a complete redesign of the airplane: instead of generating negative lift like a conventional aft-tail, the canard adds positive lift and delays the onset of stall. Whether the foreplane is fixed, variable-geometry, or hinged for control, the resulting configuration integrates these extra surfaces into the aircraft's overall wing system, giving the pilot better authority and the airframe a distinctive silhouette.
How do canards work on a plane?
Canards work in conjunction with the foreplane. During flight, the foreplane is placed forward of the main wing and behaves as a fuselage-mounted horizontal surface that modifies airflow over the main wing. The control canard works like a forward-mounted elevator: it deflects, the nose pitches, and both surfaces work in tandem to maintain the airplane airborne while the main wing carries the aircraft's weight. Because the canard must stall before the main wing, the surface allows the plane to increase its angle of attack without risking loss of control. Vortices help keep airflow attached to the vehicle and so the stall arrives gently at a higher lift coefficient. While a conventional tail typically pushes down with a negative trimming force, the lifting canard instead adds lift so the main wing needs to be larger than expected from reduced load, yet this reduces the net drag.
What are the advantages of canard aircraft?
Canard surfaces give a boost in agility and better pitch control by generating extra lift instead of the negative lift of a conventional horizontal stabiliser, so the main wing can be smaller and the whole aircraft lighter with less drag. This positive lift lets designers reduce wing loading and improves the lift-to-drag ratio, making the configuration more efficient than traditional airplanes, especially at high angles of attack. Because the foreplane stalls first, the layout is advertised as stall-proof and safety is refined through natural aerodynamic angle-of-attack limiting, while still allowing larger control authority at higher lift coefficients than unstable aft-tail configurations. The foreplane supports short takeoffs and landings and permits quicker, accurate responses in tight turns or aggressive aerobatics, benefits that are magnified when the canard is incorporated with advanced flight-control systems.
The Chinese Chengdu J-10 and the Sukhoi Su-30MKI adopt canards to boost manoeuvrability and responsiveness, and Sweden's delta/canard Gripen was chosen because the configuration offers very low supersonic drag, proving that canards refine regional dominance, sortie rate and overall mission effectiveness without adding weight near the engine compartment.
What disadvantages of aircraft with canards include?
Disadvantages of aircraft with canards are that canards increase sensitivity to turbulence, cause adverse yaw-roll coupling, and raise radar return, making the aircraft more visible on radar. Because the canard creates strong downwash, the main wing works in a reduced-angle-of-attack setting, and any attempt to recover lift with increased wing sweep adversely affects low-speed performance. In the low-speed regime a deep stall occurs if the main wing stalls first. The tail sinks, causing the angle of attack to increase rather than decrease. The stall deepens and becomes unrecoverable, and pitch stability and low-speed performance suffer adversely. The canard still requires the rudder surface and elevons have to be large, so the total surface area grows, increasing weight and drag. The canard design typified by VariEze expects reduced directional stability and damping because of the short moment arm to vertical tail. The trim drag may be less compared to the traditional tail in a canard airplane.
