During the first months of World War I, aviation, was still a new technology which was exhibited in the seemingly ungainly aircraft of the time. One of these early designs, the Vickers ‘Gunbus’ proved it was more than just an awkward ‘kite’, and it became one of the first successful designs of the war.
By Seth Marshall
The first year of the World War I was a tremendous learning experience for all of the militaries involved in terms of aviation. Before the war began, aircraft were seen primarily as platforms for reconnaissance- early military aircraft were armed with cameras, not with machine guns and bombs. Nonetheless, within a short time, pilots and observers began carrying with them pistols and rifles with the intention of shooting down other observation aircraft. However, even before the war began, the potential for use of aircraft in combat was being explored. Bombs were first dropped from aircraft during the Balkan Wars of 1912-1913. Around the same time, aircraft designers began considering the possibility of creating aircraft specifically intended to destroy other aircraft.
The first aircraft to be specifically designed for aerial combat was the Vickers F.B.5 ‘Gunbus’. In 1912, the British Admiralty issued an order for a scout aircraft armed with a machine gun. The Vickers firm, still new to aircraft design at the time, came up with a new prototype designated the E.F.B.1- “Experimental Flying Biplane 1”. Designed by Archibald Lowe, the first prototype, nicknamed ‘The Destroyer’, was flimsy and ungainly in appearance, with staggered unequal-span wings. It was equipped with a V-8 Wolseley engine which produced a measly 80-horsepower, and armed with a single 7.7mm machine gun. ‘The Destroyer’ was unveiled during the 1913 Olympia air show in London, but crashed on its initial flight because the machine gun, mounted in the nose, disrupted the center of gravity.
Vickers was not dissuaded by the failure of their first fighter design. A series of experimental pusher-type aircraft followed the E.F.B.1- these aircraft featured the pilot and observer/gunner in seats located in front of the engine; the engine itself was mounted facing the rear of the aircraft. The second plane, the E.F.B.2, also crashed. The third design, the E.F.B.3, ditched the wing-warping controls used in the previous two designs in favor of ailerons, flaps which control the roll-rate of flight. This version was more successful, and the Admiralty ordered six aircraft in late 1913. Finally, in the first half of 1914, the F.B.5 was designed. The F.B.5 was given a more powerful engine, a 100-horsepower Gnome rotary engine. Additionally, the tail structure was redesigned to with several beams forming a V-shape, with the rudder mounted at the apex of the V-shape. 
The new aircraft first flew on July 17, 1914, just weeks before the war broke out. Weighing just over 2,000lbs, the F.B.5 was capable of only reaching a top speed of 70 mph, slow even by the standards of the day. The F.B.5 had a maximum ceiling of 9,000 feet. In November, the first production F.B.5 aircraft began reaching Royal Flying Corps (RFC) units- the first squadron to receive the new aircraft was No. 6 Squadron. As was common for the time, the F.B.5 equipped squadrons piecemeal initially- most RFC squadrons flew a motley of aircraft during the first months of the war. It would not be until 1915 that F.B.5’s would be committed to action over the Continent. The first squadron to solely operate the F.B.5 was No. 11 Squadron, formed in February 1915 with the specific purpose of destroying other aircraft. In July, the squadron moved to an aerodrome near a racetrack at St. Omer, France. The nickname “Gunbus” was acquired through the escort duties that the type performed for unarmed reconnaissance planes. No. 11 Squadron thus had the distinction of becoming the first fighter squadron in history.
The operational life of the F.B.5 Gunbus was relatively short. The type’s slow speed, sluggish rate of climb, and mediocre ceiling meant that it was quickly eclipsed by newer aircraft types on both sides. Additionally, numerous problems were encountered with the Gunbus’ engine, which was considered unreliable. Maurice LeBlanc-Smith later recalled:
“… the Vickers seemed a more robust aircraft, but my chief recollection, apart from the smell of castor oil that blew into our faces and probably helped to keep us fit, was the unreliability of the 100hp Gnome engine. One great fault was the breakdown of the expanding piston ring, shaped like an L… It frequently would not stand up to the heat and would buckle or break, with consequent loss of power…”
Beginning in late 1915, the introduction of the German Fokker Eindekker effectively signaled the end of the operational life of the Gunbus. The Eindekker was faster and far more maneuverable- the Gunbus couldn’t even dive away for safety. As a result, by early 1916, the F.B.5 had been withdrawn from frontline service. Before it was phased out, the F.B.5 did have a moment of glory. On November 7, 1915, an F.B.5 from No. 11 Squadron, crewed by pilot Second Lieutenant Gilbert Stuart Martin and gunner First Class Air Mechanic T.H. Donald, shot down a German Aviatik and were then themselves brought down by ground fire. However, both crew were able to repair the Gunbus, take off, and return to base. Both were later awarded the Victoria Cross, Britain’s highest military honor. Nonetheless, the Gunbus’ operational days were numbered. By mid-1916, the F.B.5 had been relegated to the role of trainer. An improved version of the F.B.5, the F.B.9, was built in some numbers, but was generally unsuccessful.
Ultimatley, 125 F.B.5s were built by Vickers and delivered to the RFC- 109 of these served in the BEF. Another 75 aircraft were built under license in France by Societe Anonym Darracq between 1915-1916. Finally, 12 examples were built by the Danish company Tojhusvasrksted during 1917-1918. Today, no original examples of the F.B.5 survive. Several replicas exist, including one built in the 1960s that flew for a number of years in the UK. While the Gunbus had a relatively short operational life, it was an important step in military aviation design as the first purpose-built fighter aircraft. Additionally, the design of the F.B.5 informed later successful pusher-type aircraft designs, including the Royal Aircraft Factory F.E.2b two-seater and Airco D.H.2 single-seater fighters, both of which were important to eliminating the advantage that the Luftstreitskrafte had gained with the Fokker Eindekker. Though not a instrumental aircraft, the F.B.5 was an important stepping stone of First World War aviation.
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 Dog-Fight: Aerial Tactics of the Aces of World War I, p. 21-22