Vickers EFB-5 / FB.5 Gunbus
Progressive changes introduced by successive E.F.B.3s led to the E.F.B.5 - the E.F.B.4 being a project with a more streamlined nacelle centred between the wings and only two tailbooms - which was flown from Joyce Green to Brooklands on 17 July 1914. In parallel, Vickers developed the E.F.B.6, which, basically similar to the E.F.B.5, had longer-span upper wings. It lacked top decking between the two crew seats and had ailerons in the upper wings only. At Brooklands on 14 July 1914, the E.F.B.6 was taken on strength by the Royal Flying Corps when World War I began, but was not developed.
No orders were received but Vickers felt certain that war was imminent and began building 50 F,B.5s. These were eventually taken over by the RFC, which put a total of 241 in service. The E.F.B.5 was ordered into production for both the RFC and the RNAS on 14 August 1914, the first series aircraft being completed in the following October. At this time, the aircraft became simply F.B. (Fighting Biplane) 5 and was dubbed Gunbus. The E.F.B.5 had retained the semi-circular tail-plane of the E.F.B.2 and early E.F.B.3, but the series F.B.5 had an enlarged tailplane of rectangular planform and a larger rudder. A Lewis gun on a more practical mount supplanted the similar-calibre Vickers in the nose and the standard power plant was the 100hp Gnome Monosoupape nine-cylinder rotary.
The true fighter squadron was born on the 14 February 1915 when No.11 Squadron was formed at Netheravon. Completely equipped with Vickers FB5 aircraft this was the first unit established purely with the intention of destroying other aircraft.
The first F.B.5 reached the Western Front early February 1915, and, on the following 25 July, the first squadron of any air service formed specifically for fighting duties and equipped throughout with a single aircraft type arrived in France, this being the RFC's No 11 Sqn with F.B.5s.
The RNAS made little use of the F.B.5, and, after the delivery of four to that service, the large majority of subsequent deliveries went to the RFC, although the RNAS did receive two further F.B.5s which, ordered in May 1915, were fitted with the 150hp Smith Static radial engine, its large diameter propeller necessitating the raising of the fuselage nacelle several inches above the lower wing. Two hundred and forty-one F.B.5s were delivered to the RFC, of which 109 were sent to the British Expeditionary Force in France (60 in 1915 and 49 in 1916). Licence production of the F.B.5 was undertaken in France by the Societe Anonym Darracq (which built a total of 99 of these and the later F.B.9) between May 1915 and June 1916. Twelve were also built under licence in Denmark in 1917-18 by the Tojhusvasrksted. At least four F.B.5As were built with armour-plated fuselage nacelles and these were powered by 110hp Clerget 9Z nine-cylinder rotary engines and had oleo undercarriages. Suffering an unreliable engine and a marginal performance throughout its operational career, the F.B.5 was finally withdrawn from the Western Front in the autumn of 1916, being subsequently confined to RFC instructional units.
Engine One 100 hp Gnome Monosoupape
Length 27 ft 2 in (8.25m)
Wing span 36 ft 6 in (11.1m)
Height: 3.38 m / 11 ft 1 in
Wing area: 35.49 sq.m / 382.01 sq ft
Weight empty 1,220 lb (553 kg)
Max take-off weight: 930 kg / 2050 lb
Max speed: 70 mph (113 kph) at 5000 ft
Range: 402 km / 250 miles
Service ceiling: 9,000 ft (2,700 m) fully loaded
Endurance 4.5 hours
Armament: One Lewis machine gun, plus small bombs
Vickers F.B.5 Gunbus