The Sopwith 1½ Strutter was a British biplane designed and built by the Sopwith Aviation Company during World War I. It was a two-seater aircraft with a single engine and was used primarily as a reconnaissance and bomber aircraft, but it also served as a fighter.

The Sopwith 1½ Strutter had a unique design feature in which the top wing was positioned forward of the bottom wing, allowing the observer to have an unobstructed field of view for reconnaissance purposes. It was armed with one or two forward-firing machine guns for the pilot and one or two flexible Lewis machine guns for the observer.

The aircraft was powered by a variety of engines, including the 110 hp Clerget 9Z rotary engine, which gave it a top speed of around 160 km/h (100 mph) and a ceiling of 4,600 meters (15,000 feet).

The Sopwith 1½ Strutter was widely used by the Royal Flying Corps and the Royal Naval Air Service during World War I, particularly on the Western Front. It was used in a variety of roles, including reconnaissance, artillery spotting, bombing, and ground-attack. It was also used as a fighter aircraft, particularly during the early stages of the war when the demand for fighter planes was high.

Overall, the Sopwith 1½ Strutter was a successful aircraft design and played an important role in the early years of air warfare. It was eventually replaced by newer aircraft designs towards the end of the war, but it remained in service with some air forces until the early 1920s.