# # # I. Basic functions and classification of landing gear
Landing gear is an important device used to support the weight of aircraft, absorb impact energy and guide the direction of aircraft during takeoff, landing and taxiing. According to the installation position and structural characteristics, landing gear is mainly divided into two categories: fixed landing gear and retractable landing gear. The fixed landing gear has a simple structure, but it increases the flight resistance of the aircraft; The retractable landing gear can be retracted during flight, reducing flight resistance and improving flight efficiency.
# # # Second, the multi-style design of landing gear
1. ** Front three-point landing gear * *
The front three-point landing gear is the most common landing gear layout in modern aircraft, which consists of two main landing gears located under the wing or slightly behind the fuselage, and one front landing gear located under the nose. This layout makes the aircraft have good stability and maneuverability when taking off, landing and taxiing, and it is the design adopted by most civil and military aircraft at present.
2. ** Rear three-point landing gear * *
The rear three-point landing gear is often used in early aircraft, which consists of a main landing gear under the fuselage and two tail wheels (or tail struts) on both sides of the tail. Although this layout is not stable during take-off and landing, it is a feasible choice under the technical conditions at that time. With the development of aviation technology, the rear three-point landing gear is gradually replaced by the front three-point landing gear.
3. ** Bicycle landing gear * *
Bicycle landing gear is a special layout, and its two main landing gears are located on both sides of the fuselage, and the position is high, similar to the wheels of a bicycle. This layout is more common in some special-purpose aircraft, such as vertical take-off and landing aircraft or some small drones. Bicycle landing gear can reduce the turning radius of aircraft when taxiing on the ground and improve maneuverability.
4. ** Multi-wheeled landing gear * *
For large aircraft, such as wide-body passenger aircraft, transport aircraft and heavy bombers, in order to disperse the weight, reduce the pressure and increase the stability, multi-wheeled landing gear is usually used. Each main landing gear of this landing gear is equipped with multiple wheels (usually two or more pairs) to ensure the stability and safety of the aircraft during takeoff, landing and taxiing.
# # # Third, the technical innovation of landing gear
With the continuous development of aviation technology, the design of landing gear is also constantly innovating. For example, using light and high-strength materials (such as titanium alloy and composite materials) to reduce weight and improve performance; Adopt advanced damping system to absorb more impact energy and protect the aircraft structure; And intelligent control system is adopted to realize automatic retraction and fault diagnosis of landing gear. These technological innovations not only improve the safety and reliability of aircraft, but also promote the sustainable development of aviation industry.
# # # Conclusion
Aircraft landing gear is an important part of aircraft, and its diversified design styles and continuous technological innovation provide a strong guarantee for the safe flight of aircraft. In the future, with the continuous progress of aviation technology and the continuous expansion of aviation market, we have reason to believe that the design of landing gear will be more advanced and humanized, which will escort the blue sky dream of mankind.
