The Sopwith Strutter was a British single- or two-seat multi-role biplane aircraft of the First World War. It was 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 Strutter because of the long and short cabane struts that supported the top wing. The type was operated by both British air services and was in widespread but lacklustre service with the French . Design and development [[File:An aeroplane leaving the deck of the Australia on a reconnaissance trip (13960807682).jpg|thumb|Sopwith 1 1/2 Strutter biplane aircraft taking off from a platform built on top of HMAS Australias midships 'Q' turret. 1918]] In December 1914, the Sopwith Aviation Company designed a small, two-seat biplane powered by an Gnome rotary engine, which became known as the "Sigrist Bus" after Fred Sigrist, the Sopwith 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.Jarrett 2009, p. 56. 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 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 Strutter. The first prototype was ready in mid-December 1915, undergoing official testing in January 1916.Bruce 28 September 1956, p. 544. The Strutter was of conventional wire-braced, wood and fabric construction. The pilot and gunner sat in widely separated tandem cockpits, with the pilot in front, giving the gunner a good field of fire for his Lewis gun. The aircraft had a variable-incidence tailplane that could be adjusted by the pilot in flight and airbrakes under the lower wings to reduce landing distance.Jarrett 2009, pp. 56, 8. The Vickers-Challenger synchronisation gear was put into production for the Royal Flying Corps (RFC) in December 1915 and in a few weeks, a similar order for the Scarff-Dibovski gear was placed for the RNAS.Bruce 5 October 1956, p. 586. Early production Strutters were fitted with one or the other of these gears for