The Felixstowe F.3 was the most numerous of the British Felixstowe flying boats, and had a wider wingspan and could carry a heavier payload than the earlier F.2A, although at the cost of reduced agility.
The Felixstowe flying boats were directly descended from the Curtiss H-1 America, a twin engined pusher biplane flying boat that had been built in 1914 to try and fly across the Atlantic. After the outbreak of war one of its pilots, John Porte, a formal officer in the Royal Navy, returned to Britain, where he became commander of the Naval Air Station at Felixstowe. He convinced the Navy to purchase the two H-1s and place orders for the similar Curtiss H-4. In service these aircraft performed well in the air, but were felt to be rather too fragile on the water. Porte and his team carried out a series of experiments with new hulls, which produced the sole Felixstowe F.1. The next Curtiss design, which the British called the H-8, was even worse on the water, and couldn’t take off with a full load. Once again Porte combined the Curtiss wings with a new hull, producing the Felixstowe F.2. This entered production as the F.2A, although not until the start of 1919. The F.2A handled just as well as the Curtiss aircraft in the air, but much better on the water, both at take off and landing.
The one flaw with the F.2A was it’s poor payload – it could only carry two 230lb bombs, which was rather limited when used against U-boats. The Felixstowe F.3 was the first member of the family not to be developed directly from a Curtiss original. It was similar to the F.2A, but with a 4ft 16 1/2in increase in wingspan and 2ft 11in in length. This improved its range and payload, allowing it to carry four 230lb bombs. However it kept the same 345hp Rolls-Royce Eagle engines, so lost some speed and manoeuvrability, and with it the ability to attack Zeppelins and tangle with enemy floatplanes. A new method of building the planing bottom was used, but this wasn’t a great success, and made the aircraft more likely to leak.
The prototype, which was a modified F.2C, made its maiden flight in October 1917, when it was powered by two 320hp Sunbeam Cossack engines. Production aircraft used the Rolls-Royce Eagle VIII. This aircraft then entered operational service, but was considered to be worn off by April 1918 and was struck off.
A total of 263 F.3s were produced, including 18 built at the Dockyard Construction Unit at Malta. As with the F.2 several companies were involved in production of the F.3, including Short Brothers, Dick, Kerr & Co and the Phoenix Dynamo Co. About 100 were completed before the end of the war. Unlike the F.2, the F.3 saw service overseas, and was in high demand in the Mediterranean.
The F.3 was mainly used to fly anti-submarine patrols, where its heavier payload was invaluable. The main task was to patrol the ‘spiders web’, a patrol route centred on the Hinder Light Station, which covered the area almost all U-boats had to cross to reach their operational areas. Although no U-boats were sunk purely by flying boats in this period, the constant attacks did force many to cross the area submerged, and disrupted the voyage of others, reducing the time they could spend on station.
It was also used to test out an early automatic landing device, and to test servo-operated controls. One of the Malta based aircraft also took part in the Allied fleet‘s attack on the port of Durazzo on the Albanian coast on 2 October 1918. The F.3 was declared obsolete in September 1921.
Known F.3 serial numbers include N64, N4000-N4036, N4100-N4117, N4160-N4183, N4230-N4279, N4310-4321, N4360-N4397, N4400-4429. Unspecified Felixstowe aircraft were allocated the range N4430-4579
Engine: Two Rolls-Royce Eagle VIII 12-cylinder V piston engines
Power: 345hp each
Span: 102ft 0in
Length: 49ft 2in
Height: 18ft 8in
Empty weight: 7,958lb
Maximum take-off weight: 13,281lb
Max speed: 91mph at 2,000ft
Service ceiling: 8,000ft
Endurance: 6 hours
Armament: Four 0.303in Lewis machine guns on free mounts
Bomb load: four 230lb bombs on underwing racks