09/30/2008. When towards the end of the 1930s the threat of war increased, the Dutch government decided to strengthen its defense forces. That also increased the need for pilots, observers and gunners, and a specification for a new trainer was issued late 1937. The Koolhoven company at Waalhaven, Rotterdam, responded with the private venture F.K.56. To speedup development, Ir. J. Weyer and his team modified the fuselage of nineteenth F.K.51, covered the cockpits with a greenhouse canopy, and fitted a new designed gull wing with a strutted main landing gear.

The prototype was registered PH-ASB on March 21, 1938, although it took another three months before test pilot Thomas Coppers flew it from Welschap airfield near Eindhoven on June 30, 1938. In the autumn the aircraft was presented to the Netherlands Army Air Service at Soesterberg, where it was compared with the Focke-Wulf Fw 56 Stösser (Goshawk). An order for ten aircraft was received shortly thereafter.

Development continued, the main landing gear was altered into a that version that retracted rearwards into pods under the wings, while the 420 hp Wright Whirlwind R-975E-3 was replaced by the 350 hp Armstrong Siddeley
Cheetah X. The front canopy was identical to the one on the F.K.58, while the second cockpit was left open to be fitted with a machine gun. These features were fitted to the pictured second prototype that was flown for the first time in June 1939.

The production F.K.56 was redesigned by Erich Schatzki, the tail was copied from the F.K.58, the gull wing was replaced by a more conventional one and the Wright Whirlwind was used again. By the start of the hostilities in the Netherlands on May 10, 1940, the 10 production aircraft (s/n 81 to 90, c/n 5603 to 5612) were all delivered and based at the flying school at airpark "De Vlijt" on the island Texel. None survived the early days of the war.