Sopwith 1½ Strutter

Sopwith 1½ Strutter
Role	Biplane general purpose aircraft
National origin	United Kingdom
Manufacturer	Sopwith Aviation Company
First flight	December 1915
Introduction	April 1916
Primary users	Royal Naval Air Service Royal Flying Corps Aéronautique Militaire
Number built	4,500 France 1,439 Great Britain

The Sopwith 1½ Strutter was a British single or two-seat multi-role biplane aircraft of the First World War. It was significant as the first British two-seat tractor fighter, and the first British aircraft to enter service with a synchronised machine gun. It was given the name "1½ Strutter" because of the long and short cabane struts that supported the top wing.

As well as serving with both British air services, it also saw widespread but lackluster service with the French Aéronautique Militaire.

In December 1914, the Sopwith Aviation Company designed a small, two-seat biplane powered by an 80 hp (60 kW) Gnome rotary engine, which became known as the "Sigrist Bus" after Fred Sigrist, Sopwith's Works Manager. The Sigrist Bus first flew on 5 June 1915, and although it set a new British altitude record on the day of its first flight, only one was built, serving as a company runabout.

The Sigrist Bus formed the basis for a new, larger, fighter aircraft, the Sopwith LCT (Land Clerget Tractor), designed by Herbert Smith and powered by a 110 hp (82 kW) Clerget engine. Like the Sigrist Bus, each of the upper wings (there was no true centre section) was connected to the fuselage by a pair of short (half) struts and a pair of longer struts, forming a "W" when viewed from the front, this giving rise to the aircraft's popular nickname of the 1½ Strutter. The first prototype was ready in mid-December 1915, undergoing official testing in January 1916.

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