|Koolhoven FK.58 anti-aircraft defense patrol D.A.T. (Polish) at Clermont-Aulnat, June 1940|
|First flight||17 July 1938|
|Primary users||French Air Force
Polish Air Force
The Koolhoven F.K.58 was a single engine, interceptor-fighter aircraft designed and mainly manufactured by N V Koolhoven in the Netherlands 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, the French Conseil Supérieur de l'Air decided that domestic aircraft manufacturing capacity could not, in the event of war, equip the Armée de l'Air with fighters quickly enough. The Dutch manufacturer Koolhoven was contracted to design a cheap, easily built, high-performance fighter, that could be built and serviced with French-supplied engines and other components. According to some sources, the Koolhoven fighter was intended primarily for fighter units based in French colonies.
On 17 July 1938, the prototype Koolhoven Model 1166 (later renamed the F.K.58) flew for the first time. Designed by Erich Schatzki – a Jewish refugee from Germany – the F.K.58 may be seen as a development of his preceding fighter design: the Fokker D.21. The F.K.58 used the same composite materials as the D.21: the structure of the fuselage consisted of welded steel tubing covered with sheet metal (front part) and fabric (aft); the wings had wooden members with a plywood and fabric skin.
In January 1939, the Armée de l'Air placed an order for 50 aircraft, to be powered by Gnome-Rhône 14N engines.
Due to the unavailability of Gnome-Rhône engines and French instruments, just 17 aircraft – six F.K.58s and 11 F.K.58As – were completed at the Koolhoven works, with Dutch supplied engines and instruments – and delivered to the Armée de l'Air. Production was transferred to Nevers, where the aircraft were re-built with French components and the extraneous parts were returned to the Netherlands. However, only one more F.K.58 was produced from scratch at Nevèrs.
In July 1939, the Dutch government placed an order on behalf of the Luchtvaart Afdeling (Netherlands Army Aviation Corps) for 36 F.K.58 variants, powered by Bristol Taurus engines. As the British government restricted exports of Tauruses, they were to be replaced by Dutch stocks of the Bristol Mercury VIII (as used by the Dutch Fokker D.21 and Fokker G.1A). The lower output of the Mercury, relative to the Taurus, would have allowed a top speed to some 480 km/h.
Had the Armée de l'Air received its full order of 50 aircraft, before for the Battle of France, it is unlikely that they would have changed the outcome. The F.K.58s that became operational were regarded as superior to the Morane-Saulnier M.S.406, comparable to the Bloch MB.151, and inferior to the Dewoitine D.520, as well as the latest German fighters.
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 Jasionowski's improvised squadron, the patrouille DAT (Défense Aérienne du Territoire), based at Salon and Clermont-Aulnat (now Clermont-Ferrand Auvergne Airport). 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.
- 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 built.
- First production variant powered by Hispano-Suiza 14AA radial engine, 7 built.
- Production version powered by Gnome-Rhône 14N-16 engine, 11 built.
- Polish Air Forces in exile in France
- Eskadra "Koolhoven" operated eight aircraft, probably all were FK.58A variant.
- Crew: One
- Length: 8.7 m (28 ft 6.75 in)
- Wingspan: 11 m (36 ft 1.25 in)
- Height: 3 m (9 ft 10 in)
- Wing area: 17.3 m² (186.2 ft²)
- Empty weight: 1,930 kg (4,255 lb)
- Loaded weight: 2,750 kg (6,063 lb)
- Powerplant: 1 × Gnome-Rhône 14N-16 radial engine, 768 kW (1,030 hp)
- Maximum speed: 505 km/h (314 mph)
- Cruise speed: 450 km/h (280 mph)
- Range: 750 km (466 mi)
- Service ceiling: 10,000 m (32,810 ft)
- Rate of climb: 11.6 m/s (1,130 ft/min)
- Wing loading: 159 kg/m² (32.6 lb/ft²)
- Power/mass: 0.28kW/kg (0.17 hp/lb)
- 4 x 7.5 mm FN-Browning machine guns in underwing fairings
Aircraft of comparable role, configuration and era
- Bloch MB.152
- Curtiss P-36 Hawk
- IAR 80
- Fokker D.XXI
- Hawker Hurricane
- Messerschmitt Bf 109
- Morane-Saulnier M.S.406
- Visschedijk, Johan (31 July 2014). "VAN A. SWINDELLE COLLECTION No. 8142. Koolhoven F.K.58A (PH-AVK c/n 5808)". 1000aircraftphotos.com. Retrieved 12 June 2016.
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