By July 1916 first examples of a larger Curtiss flying boat design began arriving in England. Designated H.8, these were quickly modified to accept more powerful twin 250-hp Rolls-Royce engines, and redesignated Curtiss H.12s, or 'Large Americas' as the RNAS crews usually referred to them. The Curtiss H.12 hull soon proved to be inadequate for its tasks, so Porte designed a new hull (the Porte II), resulting in all-round improvement in per-formance. With a new tail unit added, the modified craft was designated Felixstowe F.2, and its general structure became a prototype for succeeding F-boats.
Large-scale production of the F.2 was ordered, and the type began to equip RNAS units in late 1917. Carrying a crew of four, and a bombload of approximately 272 kg (600 lb), the F.2a (its production designation) could achieve a maximum speed of some 145 km/h (90 mph), with an endurance of perhaps six hours. It was cumbersome to handle and slow in manoeuvre, yet gave formidable opera-tional service for the rest of the war. With at least four machine-guns in nose, tail, and flank locations, it also gave a good account of itself when engaged by German seaplanes. The F.2a's main duty was antisubmarine hunting; an air deterrent which undoubtedly proved successful in the protection of Bri-tain's vital mercantile shipping.
Span: 29 m (95 ft 7.5 in) (upper), 20.8 m (68 ft 5 in) (lower)
Length: 14.1 m (46 ft 3in)
Height: 5.3 m (17 ft 6 in)
Maximum speed: 153.7 km/h (95.5 mph) at 609.5 m (2000 ft)