#PLANE AIRFOIL SKIN#

#PLANE AIRFOIL SKIN#

The best wing is a compromise between these two extremes to hold both turbulence and skin friction to a minimum. A wing with a low fineness ratio produces a large amount of turbulence. A wing with a high fineness ratio produces a large amount of skin friction. If the wing has a high fineness ratio, it is a very thin wing. Turbulence and skin friction are controlled mainly by the fineness ratio, which is defined as the ratio of the chord of the airfoil to the maximum thickness. The shape of the airfoil determines the amount of turbulence or skin friction that it produces, consequently affecting the efficiency of the wing.

The resulting aerodynamic properties of the wing are determined by the action of each section along the span. A wing may have various airfoil sections from root to tip, with taper, twist, and sweepback. Shape of the AirfoilIndividual airfoil section properties differ from those properties of the wing or aircraft as a whole because of the effect of the wing planform. When the force of lift on an aircraft’s wing equals the force of gravity, the aircraft maintains level flight. Within limits, lift can be increased by increasing the angle of attack (AOA), wing area, velocity, density of the air, or by changing the shape of the airfoil. Thus, a pressure differential is created between the upper and lower surfaces of the wing, forcing the wing upward in the direction of the lower pressure. This increased velocity, according to Bernoulli’s Principle, means a corresponding decrease in pressure on the surface. To do this, the air passing over the top surface moves at a greater velocity than the air passing below the wing because of the greater distance it must travel along the top surface.

Air flowing over the top surface of the wing must reach the trailing edge of the wing in the same amount of time as the air flowing under the wing. The difference in curvature of the upper and lower surfaces of the wing builds up the lift force.

Plane airfoil