Koolhoven FK.52
| Koolhoven FK.52 | |
|---|---|
|
|
| Type: | Fighter , reconnaissance and light bomb aircraft |
| Design country: | |
| Manufacturer: | |
| First flight: |
February 9, 1937 |
| Number of pieces: |
5 + 1 prototype |
The Koolhoven FK.52 was a military multipurpose aircraft of the 1930s developed by the Rotterdam- based Dutch Koolhoven Flugzeug AG (NV Koolhoven vfluguigen) . Only a small number of them were built.
Development and use
The prototype of the FK.52 began its flight tests on February 9, 1937. It had good flight characteristics, good climbing performance, was still fully controllable even in slow flight and required a correspondingly short runway. The good test results prompted the Dutch Air Force to order five aircraft, but before delivery could be completed, the prototype was destroyed in a crash on August 11, 1937. The small series was nevertheless completed and put into service.
When the winter war began with the Soviet invasion of Finland in November 1939 , foreign volunteers volunteered to fight in the Finnish armed forces or privately procured military equipment for the Finnish troops. In this context, the Swede Carl Gustaf von Rosen from the Netherlands acquired two of the five FK.52 and made them available to the Finnish Air Force , which used the aircraft for reconnaissance and as light bombers throughout the conflict and beyond during the Continuation War . The three aircraft that remained in the Netherlands were scrapped in 1940 after the German occupation of the country .
construction
The FK.52 was a einstieliger, strained and staggered biplane in composite construction with an upper and lower wing span and the same depth. The fuselage consisted of a welded tubular steel frame with an oval cross-section and fabric covering. The crew cabin with the seats one behind the other had a closed hood which, at the height of the front seat, had a hinged roof for the pilot to enter. The observer sitting behind it and at the same time gunner reached his workplace through a side door. To operate the defensive armament, he opened the rear part of the hood, which could be thrown off as a whole in an emergency. The two fuel tanks under the driver's seat with a total volume of 550 l could also be dropped. Suspensions for bombs up to 100 kg, which could be triggered by both occupants, were also housed in the fuselage.
The supporting structure consisted of upper and lower wings, each of which had two spars and straps made of spruce wood with planking made of plywood . The staggering of the wings was arranged so that the rear spar of the upper wing was level with the front spar of the lower wing. The connection with each other was made by N-posts and crossed tension wires, the upper wing was connected to the fuselage by a canopy . Fabric-covered metal ailerons were only on the lower wings.
The cantilever tail unit consisted of height and vertical tail with statically balanced treble and rudder . A trim tab that could be adjusted in flight was also attached to the elevator , while the trim tab on the rudder was linked to the operating mechanism. Like the ailerons, they consisted of a metal frame covered with fabric.
The FK.52 had a non-retractable main landing gear made of free-standing, clad and oil-damped Koolhoven struts and oil-pressure-braked wheels with low-pressure tires. The tail wheel sat in a fork and was rotatable through 360 °.
Technical specifications
| Parameter | Data |
|---|---|
| crew | 2 |
| span | 9.8 m |
| length | 8.3 m |
| height | |
| Wing area | 28.4 m² |
| Wing loading | 79.3 kg / m² |
| Power load | 2.7 kg / hp |
| Area performance | 29.2 hp / m² |
| Empty mass | 1350 kg |
| Preparation mass | 2135 kg |
| Payload | 115 kg |
| Takeoff mass | normal 2250 kg maximum 2500 kg |
| drive | an air-cooled nine-cylinder - radial engine |
| Type | Bristol Mercury VIII |
| power | 800 PS (588 kW) at an altitude of 4750 m |
| Fuel volume | 550 l |
| Top speed | 300 km / h near the ground, 370 km / h at an altitude of 4750 m |
| Marching speed | 315 km / h at an altitude of 4750 m |
| Rate of climb | 8.9 m / s near the ground, 10.0 m / s at an altitude of 4750 m |
| Rise time | 3.7 min at 2000 m altitude 8.3 min at 4750 m altitude |
| Service ceiling | 9200 m |
| Range | 1050 km at cruising speed |
Users
literature
- Peter Alles-Fernandez (Ed.): Aircraft from A to Z. Volume 2. Bernard & Graefe, Koblenz 1988, 3-7637-5905-0, p. 432.
- Werner von Langsdorff : Handbook of aviation. Year 1939 , 2nd, unchanged edition, J. F. Lehmann, Munich 1937, p. 328/329.
Web links
Individual evidence
- ^ Rainer Göpfert, Rolf Jakob: The Finnish Winter War. in Flieger Revue Extra No. 11, Möller, 2005, p. 51.