# # # 1. Bear and transmit pneumatic load
The skin structure composed of aircraft skin and skeleton has great bearing capacity and stiffness, but its own weight is very light, which plays the role of bearing and transmitting aerodynamic loads. After the skin bears aerodynamic force, it transfers the force to the connected fuselage wing skeleton, so the skin material is required to have high strength and good plasticity.
# # # Second, maintain the aerodynamic shape of the aircraft
The direct function of aircraft skin is to form a streamlined outer surface of the wing. In order to make the drag of the wing as small as possible, the skin should be as smooth as possible to reduce its concave-convex deformation in flight. In addition, the skin also participates in the overall force of the wing, and is combined with the spar or wing wall to form a closed box-type thin-walled structure to bear the torque of the wing. When the skin is thick, it, together with the stringer and the wing lyna strip, forms a wallboard, which bears the shear force caused by the bending moment of the wing.
# # # Third, use special skin to improve performance
* * * Corrugated skin * *: It has strong deformation resistance in some directions and good specific strength. The test shows that when countless fine grooves are laid along the flight direction, the surface strength of the aircraft body is greatly improved and the relative flight resistance is the minimum. However, when the groove direction is perpendicular to the flight direction, although the wing skin can effectively suppress the wing lift deformation along the spanwise direction caused by lift, the resulting flight resistance may be greater. Corrugated skin has been successfully applied in some aircraft models.
* * * Composite skin * *: Because of its special excellent performance, it is widely used in the wing structure of the fourth generation fighter and aircraft designed in recent years. Composite skin has the advantages of high strength, high stiffness, high stability and light weight, which helps to reduce the weight of aircraft and improve the overall performance of aircraft.
To sum up, aircraft skin plays a vital role in the design and operation of aircraft. It not only bears complex aerodynamic loads, but also maintains the aerodynamic shape of the aircraft, ensuring the stability and safety of the aircraft in flight.
