biplanes

A biplane is a fixed-wing aircraft with two main wings, one above the other. The wings are typically connected by interplane struts and bracing wires, forming a box-like structure. Some biplanes use wing staggering, where the upper and lower wings are horizontally offset, and a few designs employ unequal spans, a configuration known as a sesquiplane.

The dual-wing layout provides high lift at low speeds and allows a strong, lightweight structure suitable for early engines. This made biplanes common in the early 20th century. The trade-off is greater aerodynamic drag and interference between the wings, which reduces top speed and fuel efficiency. As aerodynamic knowledge and engine power improved, cantilever monoplanes offered superior performance, leading to a decline in practical use of biplanes after the 1930s.

In World War I, biplanes dominated military aviation, serving as fighters, reconnaissance aircraft, and trainers. Famous examples include the Sopwith Camel, SE5a, and the Fokker D.VII. After the war, biplanes remained widely used for training and sport, with types such as the Avro 504, Bristol Scout, Stearman PT-17, and the de Havilland Tiger Moth becoming common in civil aviation and air forces worldwide.

Today, biplanes are largely relegated to vintage, sport, and aerobatic roles. They are flown by enthusiasts, museums, and air shows, and several manufacturers produce accurate reproductions or kit aircraft. Modern aviation has mostly shifted to monoplanes, though the biplane design remains of historical interest for its engineering and aviation heritage.