The main components of the aircraft include the wing, fuselage, tail wing, engine, landing gear and control system. Determining the number, overall dimensions and mutual positions of these main components is the work of aircraft designers in aerodynamic layout design. It is a very key link in aircraft design. Aerodynamic layout determines the flight performance of the aircraft, and also determines whether the aircraft (especially military aircraft) can meet its use requirements and tactical and technical requirements.
In the aerodynamic layout, the most basic thing is the selection and layout of wings and tail wings. The wing is the big wing of the aircraft and the main aerodynamic lift surface of the aircraft. The aircraft can fly in the air and mainly rely on it to generate lift. The small wing behind the wing is called the tail wing. The tail wing includes horizontal tail wing and vertical tail wing. It is the auxiliary lift surface of the aircraft and plays the role of balancing and stabilizing and controlling the flight attitude.
The layout of the wing in front and the horizontal tail in rear is called normal layout, also known as conventional layout. The normal layout has been adopted for the longest time and is widely used. Both military aircraft and civil aircraft have more design and use experience in this regard. This layout can also give better consideration to low-speed flight performance such as take-off and landing and high-speed flight performance at the same time. It is a relatively mature and balanced layout form.
The layout of horizontal tail in front and wing in back is called duck layout. The front horizontal tail wing in the canard layout is also called canard wing, which is also the origin of the name of the layout. The center of gravity of the aircraft with canard layout is before the lift action point provided by the wing, so it will produce a bow torque, but the front canard wing produces positive lift, which can balance this bow torque and reduce the trim resistance while increasing the lift of the aircraft. At the same time, when the vortex generated by the canard flows through the wing, it can well increase the lift of the aircraft.
In addition, the canard wing will also produce static instability, which can make the fighter change the flight attitude faster. These characteristics are conducive to improving the maneuverability and high-speed flight performance of the aircraft, so the canard wing is very suitable for military aircraft, especially fighter aircraft emphasizing air combat capability. The disadvantage is that it will affect the maneuverability of the aircraft. However, the problem of flight control can be better solved by using active control technology. France's Rafale, Sweden's jas-39 and China's J-10 are all successful canard fighters.