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Shaped surface, such as an airplane wing, tail, or propeller blade, that produces lift and drag when moved through the air. An airfoil produces a lifting force that acts at right angles to the airstream and a dragging force that acts in the same direction as the airstream. High-speed aircraft usually employ thin, low-drag, low-lift airfoils; slow aircraft that carry heavy loads use thicker airfoils with high drag and high lift.
This entry comes from Encyclopædia Britannica Concise. For the full entry on airfoil, visit Britannica.com.