Koolhoven F.K.58

The Koolhoven F.K.58 was a single engine, interceptor-fighter aircraft designed by Koolhoven under contract by France. Intended for Armée de l'Air use, the F.K.58 saw limited service in the Battle of France.

Design and development
In 1937, as it became apparent to the French Air Council that domestic manufacturers would not be sufficient to equip the Armée de l'Air with enough fighters, the Dutch were contracted to produce a cheap, high performance fighter to supplement French construction. As produced, the F.K.58 was rather better than the M.S.406 and comparable to the Bloch MB.151 but inferior to the D.520 and most of the German aircraft it faced. It was of composite construction like the British Hurricane with a body of wooden and steel tubing and a skin of metal plates and linen. The wings were made entirely of wood.

The prototype Koolhoven Model 1166 (later named F.K.58) first flew on 17 July 1938. The French placed an order for 50 F.K.58s in January 1939, and the Dutch also placed an order for 36 fighters based on the performance of the second prototype (the first having been destroyed in a crash) but powered by Bristol Taurus engines. Unfortunately, just 17 of the French order were completed at the Koolhoven works due to insufficient French-supplied engines and instruments, and they were subsequently sent to France fitted with Dutch equipment. Production was transferred to Nevèrs where just one more F.K.58 was produced. The completed fighters (7 F.K.58s, 11 F.K.58As) were fitted with French equipment and their loaner parts returned to the Netherlands.

Even had the order of 50 aircraft been available for the Battle of France, it is unlikely that the small number of aircraft, outclassed as they were by German fighters, could have changed the outcome much. Had they been employed in their intended role as colonial fighters, they might have acquitted themselves well against the Italian aircraft in that theatre.

Operational history
The F.K.58 was originally procured for use as colonial fighters. Instead, the 13 fighters operational by May 1940 were manned by expatriate Polish pilots of Captain Walerian Jasionkowski's improvised escadre, the patrouille DAT (Défense Aérienne du Territoire) based at Salon and Clermont-Aulnat. As delivered, the fighters were not armed and the Poles had to acquire machine guns and fit them. From 30 May 1940, they were used in the defence of French cities, patrolling in Avignon - Marseille area, then from Clermont-Ferrand, without any encounters with the enemy. The type's service life was short-lived with only 47 or so operational sorties recorded; the unit had no confirmed victories, but at least one F.K.58 was lost. After the fall of France, all surviving airframes were scrapped.

Variants

 * F.K.58 Prototype
 * Prototype powered by 1,080 hp Hispano-Suiza 14AA engine, 2 built.


 * FK-58 [Bristol Taurus]
 * Dutch version powered by Bristol Taurus engine, projected Dutch aircraft, none completed.


 * F.K.58
 * First production variant powered by Hispano-Suiza 14AA radial engine, 7 built.


 * F.K.58A
 * Production version powered by Gnome-Rhône 14N-16 engine, 11 built.

Operators

 * Armee de l'Air
 * Polish Air Forces in exile in France
 * Eskadra "Koolhoven" operated eight aircraft, probably all were FK.58A variant.
 * Polish Air Forces in exile in France
 * Eskadra "Koolhoven" operated eight aircraft, probably all were FK.58A variant.