designs that were to replace the B.E.2. The resulting Type 12 F.2A, was a two-bay equal-span biplane, closely based on the R.2A and R.2B designs. Prototypes In July 1916, work commenced on the construction of a pair of prototypes; on 28 August 1916, an initial contract was awarded for fifty production aircraft. On 9 September 1916, the first prototype performed its maiden flight, powered by a Falcon I engine. It was fitted with B.E.2d wings (Bristol were major contractors for the type) to save time; its lower wings were attached to an open wing-anchorage frame and had end-plates at the wing roots. On 25 October 1916, the second prototype was completed, powered by a Hispano-Suiza engine and differing from the first prototype in its tail-skid, which was integrated into the base of the rudder. It was found that the prototype's radiator arrangement obscured the pilot's field of view and the nose was redesigned around a new circular-shaped frontal radiator in the cowling. Other changes made to the first prototype during flight testing included the elimination of the end-plates from the lower wing roots and the addition of a shallow coaming around the cockpits. Between 16 and 18 October 1916, the type underwent its official trials at the Central Flying School, Upavon, during which it was tested with a four-bladed 9 ft 2 in propeller and a two-bladed 9 ft 8 in propeller. By the time of its arrival at the experimental armament station at Orfordness it had also been fitted with a Scarff ring mounting over the rear cockpit and an Aldis optical sight. Only 52 F.2A aircraft were manufactured before production began of the definitive model, the F.2B (retrospectively named Bristol Type 14), which first flew on 25 October 1916. The first 150 or so F.2Bs were powered by either the Falcon I or Falcon II engine but the remainder were equipped with the 275 hp (205 kW) Falcon III. The additional power gave the F.2B a advantage in level speed over the F.2A, while it was three minutes faster in a climb to . Armament The Bristol F.2 Fighter was armed in what had by then become standard for a British two-seater military aircraft: one synchronised fixed, forward-firing .303 in (7.7 mm) Vickers machine gun (in this case mounted under the cowling to avoid freezing) and a .303 in (7.7 mm) Lewis Gun on a Scarff ring over