Editing Wingspan (section)

==Wingspan of aircraft==
The wingspan of an aircraft is always measured in a straight line, from wingtip to wingtip, regardless of wing shape or [[Swept wing|sweep]].

===Implications for aircraft design and animal evolution===
The lift from wings is proportional to their area, so the heavier the animal or aircraft the bigger that area must be. The area is the product of the span times the width ([[Chord (aircraft)|mean chord]]) of the wing, so either a long, narrow wing or a shorter, broader wing will support the same mass. For efficient steady flight, the ratio of span to chord, the [[Aspect ratio (wing)|aspect ratio]], should be as high as possible (the constraints are usually structural) because this lowers the [[lift-induced drag]] associated with the inevitable [[wingtip vortices]]. Long-ranging birds, like albatrosses, and most commercial aircraft maximize aspect ratio. Alternatively, animals and aircraft which depend on maneuverability (fighters, predators and prey, as well as those who live amongst trees and bushes, insect catchers, etc.) need to be able to roll fast to turn, and the high [[moment of inertia]] of long narrow wings, as well as the high angular drag and quick balancing of [[aileron]] lift with wing lift at a low rotation rate, produce lower [[Yaw, pitch, and roll|roll rates]]. For them, short-span, broad wings are preferred. Additionally, ground handling in aircraft is a significant problem for very high aspect ratios and flying animals may encounter similar issues.

The highest aspect ratio of man-made wings are aircraft propellers, in their most extreme form as [[helicopter rotor]]s.
{{Further|Flight dynamics (fixed-wing aircraft)}}