Introduction to Glider Flying > Aerodynamics of Flight > Airfoil

Airfoil is the term used for surfaces on a glider that produce lift. Although many different airfoil designs exist, all airfoils produce lift in a similar manner.

Some airfoils are designed with an equal amount of curvature on the top and bottom surface. These are called symmetrical airfoils. Airfoils that have a different curvature on the bottom of the wing when compared to the top surface are asymmetrical.

The term camber refers to the curvature of a wing when looking at a cross section. A wing possesses upper camber on its top surface and lower camber on its bottom surface. The term leading edge is used to describe the forward edge of the airfoil. The rear edge of the airfoil is called the trailing edge. The chord line is an imaginary straight line drawn from the leading edge to the trailing edge.

Relative wind is created by the motion of an airfoil through the air. Relative wind may be affected by movement of the glider through the air, as well as wind sheer. When a glider is flying through undisturbed air, the relative wind is represented by its forward velocity and is parallel to and opposite of the direction of flight.