Subsonic aircraft

All current civil aircraft, including airliners, helicopters, future passenger drones, personal air vehicles and airships, as well as many military types, are subsonic.

But other considerations such as light weight, structural stiffness, manoeuvrability, ground handling and so on often benefit from a shorter span and, consequently a less efficient wing.

[4] The wings of fast subsonic craft such as jet airliners tend to be swept in order to delay the onset of these shock waves.

A number of factors influence induced drag, however, and as a practical matter a wing of elliptical planform, like that of the Supermarine Spitfire fighter of World War II, is not necessarily the most efficient.

Taper has the desirable effect of reducing the root bending stress by shifting the lift inboard, but it has been argued by some noted designers, including John Thorp and Karl Bergey, that an untapered rectangular planform is best for aeroplanes of less than 6,000 pounds gross weight.