Aspect ratio (aeronautics)
In aeronautics, the aspect ratio of a wing (AR) is a measure of its length relative to its width. Mathematically, it is defined as the square of the wingspan divided by the wing area. For wings of constant chord, this simplifies to the ratio of span to chord. Thus, a long, narrow wing has a high aspect ratio, whereas a short, wide wing has a low aspect ratio.
Aspect ratio and other features of the planform are often used to predict the aerodynamic efficiency of a wing because the lift-to-drag ratio increases with aspect ratio, improving the fuel economy in powered airplanes and the gliding angle of sailplanes.