Canard (aeronautics)
The Wrights realised that a foreplane would tend to destabilise an aeroplane but expected it to be a better control surface, in addition to being visible to the pilot in flight.
[11] For example, the Santos-Dumont 14-bis aeroplane of 1906 had no "tail", but a box kite-like set of control surfaces in the front, pivoting on a universal joint on the fuselage's extreme nose.
Immediately before and during World War II, several experimental canard fighters were flown, including the Ambrosini SS.4, Curtiss-Wright XP-55 Ascender and Kyūshū J7W1 Shinden.
The Shinden was ordered into production "off the drawing board"[clarification needed] but only prototypes had flown by the time the war ended.
It was noted for its docile slow-speed handling characteristics[citation needed] and flew for some years, being used as a testbed during development of the swept wing of the (conventional layout) MiG-15 jet fighter.
The success of this aircraft spurred many designers, and canard surfaces sprouted on a number of types derived from the popular Dassault Mirage delta-winged jet fighter.
These included variants of the French Dassault Mirage III, Israeli IAI Kfir and South African Atlas Cheetah.
The Viggen also inspired the American Burt Rutan to create a two-seater homebuilt canard delta design, accordingly named VariViggen and flown in 1972.
It has been described as an extreme conventional configuration but with a small highly loaded wing and an enormous lifting tail which enables the centre of mass to be very far aft relative to the front surface.
In a control-canard design, most of the weight of the aircraft is carried by the wing and the canard is used primarily for pitch control during maneuvering.
A pure control-canard operates only as a control surface and is nominally at zero angle of attack and carrying no load in normal flight.
Modern combat aircraft of canard configuration typically have a control-canard driven by a computerized flight control system.
The first aeroplane to achieve controlled, powered flight, the Wright Flyer, was conceived as a control-canard[30] but in effect was also an unstable lifting canard.
[24] For example, seven years after the Wrights' first flight, the ASL Valkyrie adopted the canard position in order to make the aeroplane stable and safe.
When the main wing is most loaded, at takeoff, to rotate the nose up a conventional tailplane typically pushes down while a foreplane lifts up.
By bringing the foreplane close to the wing and just above it in a close-coupled arrangement, the interactions can be made beneficial, actually helping to solve other problems too.
A free-floating canard pivots so that the whole surface can rotate freely to change its angle of incidence to the fuselage without pilot input.
In normal flight, the air pressure distribution maintains its angle of attack to the airflow, and therefore also the lift coefficient it generates, to a constant amount.
A free-floating mechanism may increase static stability and provide safe recovery from high angle of attack evolutions.
[43] Secondary movable surfaces may be added to the free-floating canard, allowing pilot input to affect the generated lift, thus providing pitch control and/or trim adjustment.
NASA has also investigated a one-piece slewed equivalent called the conformably stowable canard,[45] where as the surface is stowed one side sweeps backwards and the other forwards.
[46] The Rockwell B-1 Lancer has small canard vanes or fins on either side of the forward fuselage that form part of an active damping system that reduces aerodynamic buffeting during high-speed, low altitude flight.
[47][48] Canard aircraft can potentially have poor stealth characteristics because they present large angular surfaces that tend to reflect radar signals forwards.
[22][page needed][49] The Eurofighter Typhoon uses software control of its canards in order to reduce its effective radar cross section.
[50][51] Canards have nevertheless been incorporated in some later stealth aircraft studies such as an early mock-up of Lockheed Martin's Joint Advanced Strike Technology (JAST) contender[52][53] and the McDonnell Douglas X-36 research prototype.
