The Vickers F.B.5 (Fighting Biplane 5) (known as the “Gunbus”) was a British two-seat pusher military biplane of the First World War. Armed with a single .303 in (7.7 mm) Lewis gun operated by the observer in the front of the nacelle, it was the first aircraft purpose-built for air-to-air combat to see service, making it the world’s first operational fighter aircraft.
Vickers began experimenting with the concept of an armed warplane designed to destroy other aircraft in 1912. The first resulting aircraft was the “Destroyer” (later designated Vickers E.F.B.1) which was shown at the Olympia Aero Show in February 1913, but crashed on its maiden flight . This aircraft was of the “Farman” pusher layout, to avoid the problem of firing through a tractor propeller, and was armed with a single belt-fed Vickers gun.
The F.B.5 first flew on 17 July 1914. It was powered by a single 100 hp Gnome Monosoupape nine-cylinder rotary engine driving a two-bladed propeller, and was of simple, clean, and conventional design compared with its predecessors. In total, 224 F.B.5s were produced, 119 in Britain by Vickers, 99 in France and six in Denmark.
The first F.B.5 was delivered to No. 6 Squadron of the Royal Flying Corps (RFC) at Netheravon in November 1914. On 25 December the first use of the F.B.5 in action took place, when F.B.5 No. 664 took off from Joyce Green airfield to engage a German Taube monoplane, hitting the Taube (and possibly causing its loss) with incendiary bullets from a carbine after the Lewis gun jammed
The F.B.5 began to be seen on the Western Front when the first reached No.2 Squadron RFC on 5 February 1915The type served in ones and twos with several other units before No. 11 Squadron RFC became the world’s first fighter squadron when, fully equipped with the F.B.5, it deployed to Villers-Bretonneux, France on 25 July 1915