Basic Ideas of Wing Theory: Flow around an Airfoil

Abstract

The basic principle underlying the construction of all flying machines is the property of an inclined plane, when it is moved horizontally through the air, of producing a supporting or lifting force. This property has long been known and the most remarkable feature connected with it is that the lifting force may be very great compared with the resistance which the plane experiences in the direction opposite to its motion. The ratio of the supporting force, or lift, as it is usually called, to the resistance, or drag, may be especially high when the angle of inclination of the plane to its path (the angle of attack) is small, and when the plane is of special form, resembling the wings of a bird.