Koolhoven F.K.55

The Koolhoven F.K.55 was a Dutch fighter prototype of the 1930s. Designed as a high-performance aircraft, it never made it past the prototype stage.

Development
Design on a Koolhoven high-performance aircraft first started late in 1937. The result, finished in early 1938 was the F.K.55, a single-seat fighter of radical design with contra-rotating propellers and an engine housed behind the pilot. It had initially been proposed to do away with ailerons on the wings, and replace them with "slot-spoilers" for lateral control, however this idea was abandoned early in the project.

Of mixed metal and wood construction with wooden wings, the F.K.55's front fuselage was made of steel tube while wood formed the tail and rear fuselage. Its Lorraine Pétrel engine afforded just enough energy to take off and to stay in flight, and many designers thought that it should be upgraded to a supercharged Lorraine 12R Sterna engine which would have afforded greater performance, however this never happened.

Operational history
The aircraft flew for the first time in June 1938. It flew for two minutes then landed. Its performance and lack of ability to stay in the air due to its weak engine resulted in the project being cancelled in the same year.