The Koolhoven F.K.58 was a Dutch single-seat fighter aircraft developed in the late 1930s by N.V. Koolhoven, intended primarily for the French Armée de l’Air.
It was conceived during a period of urgent rearmament in France, which sought to supplement its domestic aircraft production by sourcing fighters from allied nations.
The F.K.58 was designed to meet French requirements for a lightweight interceptor suitable for colonial deployment and homeland defence.
Development began in early 1938, with the prototype completed and flown by July of that year.
Although the design was largely finalised before his arrival, German-born engineer Erich Schatzki—formerly of Fokker and known for his work on the D.XXI—joined Koolhoven in mid-1938 and contributed to the refinement of the aircraft’s configuration.
The F.K.58 featured a mixed construction: a steel tube fuselage with metal and fabric skin, wooden wings with bakelite covering, and a retractable undercarriage.
It was powered initially by a Hispano-Suiza 14AA radial engine, later replaced in production models by the Gnome-Rhône 14N-16.
In January 1939, the French government placed an order for 50 aircraft.
However, production was hampered by limited industrial capacity at Koolhoven’s factory and the unavailability of French-supplied engines and instruments.
Only 17 aircraft were completed, with Dutch substitutes used for instrumentation and powerplants.
To meet the order, the final 10 units were subcontracted to SABCA in Belgium, though these were never completed due to the German invasion in May 1940.
Two main variants were produced: the original F.K.58 prototype with the Hispano-Suiza engine and the F.K.58A production model equipped with the Gnome-Rhône 14N.
Armament consisted of four 7.5 mm FN Browning machine guns mounted in the wings.
Performance was respectable for its class, with a top speed of approximately 315 mph and a service ceiling of over 32,000 feet.
Operational deployment was minimal.
The aircraft were delivered to the French Air Force in early 1940 and saw brief action during the Battle of France.
Their impact was negligible due to the small number available and logistical challenges.
None were known to have survived the war.
The Koolhoven F.K.58 remains a footnote in aviation history—a symbol of the desperate measures taken by European powers on the eve of World War II.
Though technically competent and modern in design, its legacy is defined more by the constraints of its time than by its performance in combat.
