equally spaced around the cross-section of the fuselage, lying in two planes at right angles, as on a typical missile. Wings lying together in a single horizontal plane about a vertical axis, as in the cruciform rotor wing or X-wing. Wing support To support itself a wing has to be rigid and strong and consequently may be heavy. By adding external bracing, the weight can be greatly reduced. Originally such bracing was always present, but it causes a large amount of drag at higher speeds and has not been used for faster designs since the early 1930s. The types are: Cantilevered: self-supporting. All the structure is buried under the aerodynamic skin, giving a clean appearance with low drag. Braced: the wings are supported by external structural members. Nearly all multi-plane designs are braced. Some monoplanes, especially early designs such as the Fokker Eindecker, are also braced to save weight. Braced wings are of two types: Strut braced: one or more stiff struts help to support the wing, as on the Fokker D.VII. A strut may act in compression or tension at different points in the flight regime. Wire braced: alone (as on the Boeing P-26 Peashooter) or, more usually, in addition to struts, tension wires also help to support the wing. Unlike a strut, a wire can act only in tension. A braced multiplane may have one or more "bays", which are the compartments created by adding interplane struts; the number of bays refers to one side of the aircraft's wing panels only. For example, the de Havilland Tiger Moth is a single-bay biplane where the Bristol F.2 Fighter is a two-bay biplane. Closed wing: two wing planes are merged or joined structurally at or near the tips in some way. This stiffens the structure and can reduce aerodynamic losses at the tips. Variants include: Box wing: upper and lower planes are joined by a vertical fin between their tips. The first officially witnessed plane to take off and fly, the Santos-Dumont 14-bis, used this configuration. Tandem box wings have also been studied (see Joined wing description below). Annular box wing: A type of box wing whose vertical fins curve continuously, blending smoothly into the wing tips. An early example was the Blériot III, which featured two annular wings in tandem. Annular (cylindrical): the wing is shaped like a cylinder. The Coléoptère had concentric wing and fuselage. It took off