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                      *            	HISTORIQUE DU KOOLHOVEN FK 58                    *
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(Please: scroll down for english version)



Juste avant le dйclenchement du second conflit mondial, l'industrie aйronautique franзaise, alors en pleine restructuration
ne peut assumer seule l'ensemble des besoins. La France doit se tourner vers l'йtranger: les Etats-Unis avec lesquels une 
premiиre commande de 100 CURTISS H-75 est signйe en mai 1938. Mais si cet avion apparaоt au moins aussi bon que le MS-406,
il a le dйsavantage de coыter le double. Il faut donc trouver aussi bien, dans un dйlai relativement court et pas trop cher.
De la plupart des pays prospectйs, seule la Hollande semble apte а fournir des avions aux franзais.
Au mкme moment, le ministиre des colonies est soucieux de remplacer ses vieux POTEZ 25 en Asie du Sud-Est, dont les japonais
se rapprochent dangeureusement. Les Pays-Bas possиdent une expйrience indйniable en matiиre de rusticitй et de simplicitй, 
йtant donnйe l'importance de leur propre aviation coloniale. C'est donc а FRITZ KOOLHOVEN, patron de la sociйtй NV KOOLHOVEN
VLIEGTUINGEN que les reprйsentants franзais s'adressent pour la construction d'un chasseur destinй а servir en Indochine.
Ce sera le FK-58.
Cas exceptionnel, le prototype est prкt а voler en deux mois. L'avion est motorisй avec un moteur franзais de prйsйrie,
l'HISPANO-SUIZA 14 AA de 1150 hp en йtoile. Le premier vol du FK-58 (S/N 5801) а lieu le 17 juillet 1938 а WAALHAVEN avec le 
pilote d'essai THOMAS COOPERS aux commandes, train sorti et а basse vitesse. A la fin de juillet 1938, cet avion commence а 
faire parler de lui. Les performances annoncйes sont plutфt flatteuses pour l'йpoque: а 4000 mиtres, vitesse maximale, 
490 km/h, vitesse de croisiиre, 440 km/h. Le 24 septembre, le prototype immatriculй PHATO arrive а VILLACOUBLAY pour une 
premiиre sйrie d'essais et de dйmonstrations. Quelques jours auparavant, il aurait atteint en Hollande une vitesse en palier
de 504km/h.
Las, les premiers essais franзais s'avиrent dйcevants, la vitesse max atteinte en palier est de 448 km/h. Des essais de 
survitesse effectuйs par COOPERS permettent cependant d'atteindre 890 km/h en piquй.
Le capitaine LADOUSSE effectue une sйrie d'essais au CEMA avec une nouvelle hйlice; vitesse atteinte en palier а 4500m:
477km/h, et au niveau du sol: 378 km/h. Temps de montйe а 8000m: 12 minutes 45 secondes, ce qui revient а dire que ces 
performances sont lйgиrement supйrieures а celles du MS 406. Ce prototype est dйtruit lors de son vol retour vers la Hollande
Le deuxiиme prototype, immatriculй PHAVA est exposй au salon aйronautique de Paris en 1938 et est alors prйsentй comme 
l'avion le plus rapide du monde. Il ne fera son premier vol que le 14 fйvrier 1939 en Hollande.
Dиs 1938, le Lt-Gal RAAIJMAKERS йtablit dans un rapport les besoins de l'aviation nйerlandaises а 18 FK-58. Le 22 juillet
1939, ce sont finalement 40 FK-58 qui sont commandйs, initialement avec des moteurs BRISTOL TAURUS III, mais les anglais ne
pouvant fournir ces moteurs, ce sont finalement des MERCURY VII qui sont choisis. Les performances estimйes avec le MERCURY
sont les suivantes: vitesse maxi а 4400m, 460km/h, vitesse de croisiиre, 400km/h. Aucun de ces avions ne verra le jour.
FRITZ KOOLHOVEN a йgalement fait une йtude pour installer un DAIMLER-BENZ 600 sur la septiиme cellule prйlevйe sur la chaine
d'assemblage (S/N 5807). Il espиre obtenir d'autres DB600 via la Suisse. Cette modification est rapidement abandonnйe йtant
donnйe la progression des йvиnements en Europe.
C'est donc au terme du marchй N°177/9 que la France passe commande en janvier 1939 de 50 KOOLHOVEN FK-58, livrables entre 
juin et aoыt 1939. L'HISPANO-SUIZA AA ayant йtй abandonnй entre temps, les avions seront finalement йquipйs avec des GNOME &
RHONE 14N39.
Au dйbut du conflit, FRITZ KOOLHOVEN a rempli son contrat, mais pour des questions d'approvisionnement en instruments et
armement, une grande partie des avions est stockйe а Buc. Au jour de l'attaque allemande, l'armйe de l'air ne dispose que
de 14 exemplaires du FK-58 dont une majoritй d'entre eux seront menйs par des pilotes polonais qui s'illustreront ensuite
pendant la bataille d'angleterre. Et mкme si le FK-58 n'a jamais connu de combat, quasiment tous disparaitront dans la 
tourmente.

Before the beginning of the Second World War, the French aeronautic industry wasn’t capable to produce sufficient aircrafts
 to fulfill the needs. Therefore France had to call for foreign help: An order for 100 Curtiss H-75 was placed in the 
United States in May 1938. But when the aircraft proved to be just as good as the MS-406 for double the costs, the French 
realized they had to look for a cheaper one urgently. Among other prospected countries only the Netherlands seemed to be 
able to provide aircrafts to the French. Meanwhile the Colonies Ministry worried about replacing its old POTEZ 25 which was
still in use in South-East Asia, where the Japanese were dangerously getting closer. With their own Colonial Air Force, the
Dutch were undeniable more experienced with robustness and simplicity. Which is why the French official did chose FRITS 
KOOLHOVEN, owner of the NV KOOLHOVEN VLIEGTUIGEN Company, to build a fighter meant to be used in Indochina. This fighter 
would be the FK-58.

Exceptionally, the prototype was ready to fly within two months. The plane was motorized with a pre-serial French engine, 
the radial HISPANO-SUIZA 14 AA de 1150 hp. The first flight of the FK-58 (S/N 5801) takes place on July 1938 the 17th at 
the WAALHAVEN airfield near Rotterdam. Test pilot THOMAS COPPERS flies the aircraft with gear down at low speed. By the end
of July of 1938, the plane began to become famous. Their announced performances were quite good at that time; a maximum 
speed from 490 km/hr at a height of 4000 meters (305mph at 13,000ft) and a cruising speed from 440km/hr (275mph). On 
September the 24th, the prototype registered PH-ATO arrived at VILLACOUBLAY for several tests and displays. A few days 
before it would have reached a level speed form 504 km/hr (313 mph), but the first French tests were very disappointing. 
The maximum speed which was reached in level flights was only 448 km/hr at 4500 meters (278mph at 14,700 ft. Nevertheless 
in a shallow dive COPPERS managed a maximum speed of 890 km/hr (553mph)! Captain LADOUSSE performed several tests at the 
CEMA with a new propeller. With this propeller a maximum speed of 477 km/hr at a level flight on 4500 meters (296mph at 
14,700 ft) was registered, and at ground level 378km/h (235mph) wais reached. The aircraft proved capable to climb to 
8000 meters (26,200) ft in 12 minutes and 45 seconds, which meant that the performances were slightly better than the 
MS-406. The prototype was exhibited at the 1938 Pairs aeronautics show where it was advertised as the fastest aircraft in 
the world. This prototype was destroyed in a crash landing, due to an overheated engine, on its flight back to the 
Netherlands.  A second prototype registered PH-AVA made its first flight on February 14, 1939 from WAALHAVEN in the 
Netherlands.

Since 1938 Lieutenant-General RAAIJMAKERS was pointing out that the Aviation Section from the Dutch Army (LVA) needed a 
new fighter. And in July 22 1939, 36 FK-58s were ordered. First with Bristol Taurus III engines, but as the British cannot 
supply the engines the decision is taken to use spare Bristol Mercury VIII engines. The estimated performance was a maximum 
speed of 460 km/hr at 4400 meters (285mph at 14,400ft). None was ever delivered to the LVA.

FRITS KOOLHOVEN also tried to obtain a DAIMLER BENZ DB600 engine, which he wanted to install in the seventh airframe 
(S/N 5807). He hoped to be able to get some other DB600 engines via Switzerland. However this idea was quickly abandoned 
due to the developments in Europe and problems to merge the narrow V- engine with the wide fuselage.  Following the 
specifications from order 177/9, France ordered 50 KOOLHOVEN FK-58s in January 1939, which should be delivered between 
June and August 1939.  Meanwhile the HISPANO-SUIZA 14AA engines had been abandoned and the final aircrafts would be 
equipped with GNOME & RHONE 14N39 engines.  In the beginning FRITS KOOLHOVEN could keep up production as planned, however 
because of issues with the supply of instruments and armament, most aircrafts were stocked at Buc. When the Germans 
attacked only 14 Fk-58s were operational. Most of them were flown by Polish pilots who would make themselves famous 
during the Battle of Britain. The FK-58s would never see battle, nevertheless they all disappeared in the turmoil of war.