Aerofoil Theory :-

• Aerofoil or airfoil is the cross-sectional shape designed with a curved surface, giving it the most favourable ratio between lift and drag in flight. Lift is the component such that the force is perpendicular to the direction of motion, and drag is the component parallel to the direction of motion. A similar idea is used in designing hydrofoils, which is used when water is used as the working fluid. Aerofoils are highly efficient lifting shapes as they generate more lift than similarly sized flat plates of the same area and generate lift with significantly less drag.

• The designing of the aerofoil depends on the aerodynamic characteristics, which further depends on the aircraft’s weight, speed, and purpose. These are dependent on specific terms that need to be defined to understand the design. German mathematician Max Munk first devised aerofoil, and it was further refined by British aerodynamicist Hermann Glauert and others in the 1920s.

• The basic premise of the theory is that for an airfoil in a uniform flow V∞, the airfoil can be replaced by a vortex sheet along the chord line. The strength of the vortex sheet, γ(x) is determined by the condition that the camber line must also be a streamline.