For most other planforms, the chord length varies along the span. The wing area is the projected area of the planform and is bounded by the leading and trailing edges and the wing tips. The total surface area includes both upper and lower surfaces. The wing area is a projected area and is almost half of the total surface area. The aspect ratio of a wing is defined to be the square of the span divided by the wing area.
Aspect ratio is a measure of how long and slender a wing is from tip to tip.
For a rectangular wing, this reduces to the ratio of the span to the chord length. Gliders have a high aspect ratio because the drag of the aircraft depends on this parameter. A higher aspect ratio gives a lower drag and a better glide angle. The Space Shuttle has a low aspect ratio because of high speed effects. Airfoil Geometry A cut through the wing perpendicular to the leading and trailing edges will show the cross-section of the wing.