Koolhoven F.K.56

The F.K.56 was a low-wing monoplane powered by a 450 hp (336 kW) Wright Whirlwind R-975-E3 radial piston engine.^[1] Designed as a basic trainer, the F.K.56 had two seats in tandem for the instructor and pupil under a fully enclosed canopy.^[1] The first prototype flew on 30 June 1938 and had fixed conventional landing gear and a gull wing.^[1] The second prototype had retractable landing gear and was powered by a 350 hp (260 kW) Armstrong Siddeley Cheetah X engine.^[2] Testing showed that the aircraft was too stable for use as a training aircraft, while the gull wing was too complex for mass production. A new, un-gulled, wing, based on that of the Koolhoven F.K.58 fighter was therefore designed, which was incorporated in a third prototype, which reverted to the Whirlwind engine and was fitted with dual controls.^[1][2] The third prototype flew on 5 December 1939.^[2]

Ten aircraft were ordered by the Netherlands Army based on the design of the third prototype.^[1] These ten, including the re-worked first and third prototypes, were all delivered before the German invasion of the Netherlands in May 1940.^[1]

Earlier in February 1940 the Belgians had ordered twenty F.K.56 basic trainers and seven had been delivered before the rest were destroyed in an air raid on the Waalhaven factory.^[1]

 Belgium

• Belgian Air Force

 Netherlands

Data from ^[1]

General characteristics

• Crew: 2
• Length: 7.85 m (25 ft 9 in)
• Wingspan: 11.50 m (37 ft 9 in)
• Height: 2.30 m (7 ft 7 in)
• Wing area: 20 m² (220 sq ft)
• Empty weight: 1,058 kg (2,332 lb)
• Max takeoff weight: 1,600 kg (3,527 lb)
• Powerplant: 1 × Wright Whirlwind R-975-E3 Radial piston engine, 336 kW (451 hp)

Performance

• Maximum speed: 300 km/h (190 mph, 160 kn) at a height of 500m (1640 ft)
• Range: 800 km (500 mi, 430 nmi)
• Service ceiling: 7,300 m (24,000 ft)