Jane's Encyclopedia of Aviation

Armstrong Whitworth F.K.3 (UK)
   During World War I the designer Frederick Koolhoven worked for British companies, among which was Armstrong Whitworth (after the war he designed aircraft in the Netherlands under his own name). The F.K.3 was the result of Koolhoven’s attempt to improve upon the B.E.2c. which was being built in the UK by several manufacturers including Armstrong Whitworth. As well as making the aircraft easier to construct he refined the fuselage, increased the wing span and area of the fm and rudder, and put the observer in the rear cockpit.
   With the RAF Ia engine installed, maximum speed was increased by 27 km/h (17 mph) to 143 km/h (89 mph). Five hundred production aircraft were built, most serving as trainers but a number as reconnaissance, artillery spotting and light bombing aircraft in Macedonia.