Most foil shapes require a positive angle of attack to generate lift, but cambered airfoils can generate lift at zero angle of attack. The lift on an airfoil is primarily the result of its angle of attack. This force is known as aerodynamic force and can be resolved into two components: lift ( perpendicular to the remote freestream velocity) and drag (parallel to the freestream velocity). When oriented at a suitable angle, a solid body moving through a fluid deflects the oncoming fluid (for fixed-wing aircraft, a downward force), resulting in a force on the airfoil in the direction opposite to the deflection.
Foils of similar function designed with water as the working fluid are called hydrofoils. Wings, sails and propeller blades are examples of airfoils. Streamlines on an airfoil visualised with a smoke wind tunnelĪn airfoil ( American English) or aerofoil ( British English) is a streamlined body that is capable of generating significantly more lift than drag. The dolphin flipper at bottom left obeys the same principles in a different fluid medium it is an example of a hydrofoil. Cross-sectional shape of a wing, blade of a propeller, rotor, or turbine, or sail Examples of airfoils in nature and in or on various vehicles.
