What is the plane for?

Aircraft is the carrier of air transportation system. After nearly a century of development, the flight performance of aircraft has reached a very high level. Take speed as an example. Although most civil aircraft are subsonic (that is, the ratio of flight speed to sound speed or Mach number m is less than 0.75), transonic (m is between 0.75 and 1.2) and supersonic (m is between 1.2 and 5.0) civil aircraft have also been put into operation, such as 1977 of the former Soviet Union.

All aircraft can be divided into aircraft and spacecraft, the former is atmospheric aircraft, and the latter is space aircraft (such as rockets, space shuttles, planetary probes, etc.). Aircraft can be divided into lighter than air (such as balloons and airships) and heavier than air, such as airplanes and various helicopters, gliders and rotorcraft. The plane is the most important plane. Because of its many uses, there are many classification methods.

(1) classified by structure

According to different structures, aircraft can be divided into different types.

According to the number of wings, aircraft can generally be divided into biplane and monoplane.

According to the engine type, it can be divided into piston engine and propeller group aircraft and jet aircraft.

According to the number of engines, it can be divided into single-engine aircraft, double-engine aircraft, three-engine aircraft and four-engine aircraft.

According to the landing location, it can be divided into land plane, snow (ice) plane, seaplane, amphibious plane and carrier plane.

According to the take-off and landing mode, it can be divided into taxiing and taxiing take-off and landing aircraft and V/STOL aircraft.

In addition, it can also be classified according to the position or number of tails and the number of fuselage.

(2) Classification by purpose

Because the performance, structure and appearance of aircraft are basically determined by the use, classification by use is one of the most important classification methods. Modern aircraft can be mainly divided into military aircraft and civil aircraft according to their uses, and another kind of aircraft specially used for scientific research and experiment can be called research aircraft. The following mainly introduces civil aircraft.

1. passenger plane refers to the aircraft used to carry passengers and mail and contact domestic cities and regions or international cities. Passenger aircraft can be further divided into: long-range (large) passenger aircraft used on intercontinental routes; Medium-range (medium-sized) passenger aircraft used on domestic trunk lines; Short-haul (light) passenger aircraft for local routes (feeder lines). At present, most passenger planes used in various countries are subsonic. There are two kinds of supersonic passenger aircraft, and their maximum cruising speed is about twice the speed of sound. Medium-sized passenger aircraft are widely used, both jet and propeller, such as trident.

2. Cargo plane, used to transport goods, generally has a large load and a large hatch, or the fuselage can be turned over to facilitate loading and unloading goods; The cargo plane is easy to repair and maintain, and can fly in complex climate.

3. Trainers (civil) are used to train civil aviation pilots, which can be generally divided into primary trainers and advanced trainers.

4. Agricultural machinery and forestry machinery are used for agricultural spraying, fertilization, sowing, forest patrol, fire fighting, etc. Most of them belong to light aircraft.

Sports machine is used to develop sports, such as sports skydiving, which can be used for maneuvering flight.

6. Multi-purpose light aircraft There are many types and uses of this kind of aircraft, such as geological exploration, aerial photography, air tour, emergency rescue, short-distance transportation, etc.

Agricultural and forestry machinery, sports machinery and multipurpose light aircraft all belong to the category of general aviation. In the United States, Britain and other countries, general aviation generally refers to aviation activities that are neither military aviation nor conventional civil passenger and cargo transportation.