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An airplane designer tries to select an airfoil shape that will give the best possible lift-to-drag ratio at some desired optimum flight condition, such as cruise or climb, depending on the type of aircraft. The shape of the airfoil then determines the balance of lift and drag at various angles of attack. The shape of the upper and lower surfaces of the airfoil and the angle that it makes with the oncoming airflow, or angle of attack, determines the way the flow will accelerate and decelerate around the airfoil and, thus, determines its ability to provide lift.įlow around the airfoil also causes drag, and an airfoil should be designed to get as much lift as possible while at the same time minimizing drag. The higher-speed air on the top of the airfoil produces a lower pressure than the flow over the bottom, resulting in lift. Although airfoils come in many different shapes, all are designed to accomplish the same goal: forcing the air to move faster over the top of the wing than it does over the bottom. The shape revealed if a wing were to be sliced from its leading edge to its trailing edge is called the wing’s airfoil section. Significance: The shape of a wing’s airfoil section or sections determines the amount of lift, drag, and pitching movement the wing will produce over a range of angles of attack and also determines the wing’s stall behavior. Definition: A two-dimensional, front-to-back section or slice of a wing.