Tandemwing

Tandemwing is a configuration in which two lifting surfaces are arranged in tandem along the aircraft’s longitudinal axis, with one wing positioned aft of the other. The arrangement keeps the wings separated along the fuselage rather than stacked vertically as in a traditional biplane, and may involve a single fuselage or twin booms supporting the wing panels. The span and aspect ratio of the front and rear wings may be equal or different, and either surface can carry primary elevator or aileron controls.

Design considerations: The gap between the wings and their relative sizes create a distinct aerodynamic interaction. Tandem-wing designs can allow a high overall aspect ratio without requiring a single very long wing, potentially reducing wing bending moment. They can also improve stall behavior by distributing lift across two surfaces. Structural tradeoffs include increased complexity, weight, and bracing requirements, as well as drag from interference and strut systems.

Aerodynamics: The rear wing may fly in the downwash of the front wing, altering lift. Tail-first or canard interactions can be designed to complement stability. Tandem wings can be optimized for lift distribution, control effectiveness on both surfaces, and pitch stability, but they require careful aerodynamic and structural tuning to avoid excessive interference drag and adverse pitching moments.

History and usage: Tandem-wing configurations have been explored in aviation since the early days of flight and have appeared in experimental aircraft, light aircraft, gliders, and unmanned aerial vehicles. While offering potential benefits in lift distribution and span efficiency, they remain relatively uncommon in production aircraft due to complexity and limited benefits relative to more conventional layouts.

See also: canard, biplane, wing configuration, multihull aircraft, wing loading.