Armstrong Whitworth F.K.5 / F.K.6
In 1915, Frederick Koolhoven, the chief designer of Sir W G Armstrong Whitworth & Co Ltd, initiated work on a three-seat triplane powered by a 250hp Rolls-Royce 12-cylinder water-cooled engine. It was intended to accommodate two gunners each with a 7.7mm machine gun in shallow nacelles mounted above the centre wing on each side of the fuselage, the gunners being seated ahead of the propeller plane of the tractor engine. Although a prototype was completed and allegedly designated F.K.5, this was never flown, being extensively damaged as a result of a ground loop during its first take-off attempt. The design was extensively revised early in 1916 to meet an RFC requirement for an airship interceptor and long-range escort fighter.
The revised design is believed to have been designated F.K.6 and four examples were ordered, two of these being intended for the RNAS. In the event, only one F.K.6 was built. The gunners' nacelles were underslung on the central mainplane, armament remained two 7.7mm Lewis guns and the 250hp Rolls-Royce engine was retained. It is believed that relatively limited flight testing was undertaken. And no armament was actually fitted.
The middle wing was much longer than the others, but the other wings were equal span.
Engine: 1 x 250hp Rolls-Royce piston
Wingspan: 19.14 m / 62 ft 10 in