<< Page 24 Page 25: Page 26 >>   Wing Area, Wing Loading We have seen how wings that fly slower, higher and have smaller surface areas produce less lift. This means a slow airplane or a high-flying airplane will need a large wing, because the air is not producing a lot of lift per unit of area (low wing loading). An airplane that flies fast, however, can generate more lift per area, and thus needs a smaller wing. Smaller wings are also stiffer and allow for tight turns and dogfights. (wing loading = lift per area of wing) Airplanes that are very slow thus try to have as much wing area as they can and as little weight as they can, due to the small wing loading. This is true of human-powered airplanes, of solarpowered airplanes, and of all airplanes before the 1920s (which is why they were biplanes – twice the wings means twice the wing area). Planes that fly very high also have more trouble generating lift and thus need bigger wings, unless they go at several times the speed of sound. Below; The Vickers Vimy, a glider, and a Fokker triplane: Instead of moving a little air by a lot, they move a lot of air by a little, so loads on the wings are smaller, and the wings can be more flimsy, and lighter: Airplanes that fly very fast and make tight turns need stubby, small wings for strength, because of the higher loads (and also because of the lower supersonic drag). This is true of fighters, experimental high-speed airplanes, and space-reentry vehicles. So high loads require low aspect ratios. Below; The X-15 and F-16: high speed and tight turns (high loadings) call for stubby wings: