monoplane

A monoplane is an aircraft that uses a single main wing plane. This distinguishes it from biplanes and triplanes, which carry their lift on two or more wings.

In the early days of aviation, many airplanes used braced or multi-wing configurations for structural reasons. Monoplanes required stronger spars and cantilever wing designs, along with innovations in materials, to achieve adequate stiffness and load bearing without a second wing. As these technological advances accumulated, monoplanes became technically and commercially viable in the 1930s and 1940s, reducing parasitic drag and improving climb and speed. The development continued with all-metal cantilever designs and later jet-powered forms, making monoplanes the standard for most military and civilian aircraft.

Planform and wing arrangements vary widely among monoplanes, including high-wing, low-wing, and mid-wing configurations, as well as straight, swept, or delta shapes. The choice influences stability, lift distribution, drag, and ground clearance.

Notable examples span military and civilian use: World War II fighters such as the Spitfire and Bf 109; the P-51 Mustang; civil cantilever monoplanes like the Boeing 247 and the DC-3; and modern airliners such as the Boeing 707 and Airbus A320. The term monoplane also covers current single-wing designs, including many experimental tailless and blended-wing configurations.