Koolhoven FK.55
| Koolhoven FK.55 | |
|---|---|
 Project study by FK.55 |
|
| Type: | Fighter plane |
| Design country: | |
| Manufacturer: | |
| First flight: |
June 30, 1938 |
| Commissioning: |
- |
| Number of pieces: |
1 |
The Koolhoven FK.55 was a 1930s fighter aircraft designed by Frits Koolhoven in the Netherlands .
development
Koolhoven gave the aircraft a rather unconventional structure. The engine was located behind the pilot in the middle of the fuselage and drove two propellers rotating in opposite directions on the bow via an intermediate shaft and a gearbox . With this design, the FK.55 should achieve a top speed of 510 km / h and a maximum climb rate of 13.5 m / s. The wings were set high up, which is why the main landing gear was attached to the fuselage and had a rather small track width .
First a 1: 1 dummy was made, which was exhibited at the Paris Aérosalon in 1936 , where it caused quite a stir because of its original design. A prototype was then built , which was completed in 1938. He received as driving a French Pétrel - twelve-cylinder - V engine of Lorraine with 860 hp, but for series production was a much stronger Sterna -Triebwerk from the same manufacturer provided. On June 30, 1938, the FK.55 took off on its first flight, which was also its last and lasted only two minutes. No further attempts followed and the program was terminated. The concept probably failed, was too immature, or too complicated.
A bomb attack by KG 4 of the German Air Force on Waalhaven airfield in the early morning hours of May 10, 1940 , in which the Koolhoven production facility and aircraft under construction were also badly hit, also destroyed the parked FK.55.
construction
The FK.55 was a cantilever monoplane in composite construction developed. The front part of the fuselage consisted of a welded tubular steel frame up to about the level of the rear edge of the wing and behind it of a wooden frame in a shell construction . The planking consisted of smooth sheet metal. In the center of gravity under the wings , behind the pilot's seat, the engine and the fuel and lubricant tanks with a capacity of 430-510 and 39-50 l respectively were housed. The closed cabin, which was set far forward, gave the pilot a very good view.
The FK.55 had wooden wings clad with plywood with two box spars and ribs made of plywood. Spreading flaps were installed between the ailerons and the fuselage . At the stern was the cantilever tail unit in normal construction. The axleless rear wheel landing gear was pulled into the fuselage.
Technical specifications
| Parameter | Data |
|---|---|
| crew | 1 |
| span | 9.60 m |
| length | 9.25 m |
| height | |
| Wing area | 16 m² |
| Wing extension | 5.75 |
| Wing loading | 142.30 kg / m² |
| Power load | 1.69 kg / hp |
| Area performance | 84.5 hp / m² |
| Preparation mass | 1600 kg |
| Payload | 680 kg |
| Takeoff mass | 2280 kg |
| Calculated performance for series execution | |
| drive | a liquid-cooled twelve-cylinder - V-type engine having two counter-rotating twin sheet metal Verstelluftschrauben Ratier |
| Type | Lorraine "Sterna" |
| Starting power continuous power |
1,350 PS (993 kW) 1,000 PS (735 kW) |
| Fuel volume | normal 430 l maximum 510 l |
| Top speed | 510 km / h at an altitude of 3600 m |
| Marching speed | 450 km / h at an altitude of 3600 m |
| Landing speed | 115 km / h |
| Rate of climb | 13.1 m / s near the ground 13.5 m / s at 3200 m height 9.2 m / s at 6000 m height 4.8 m / s at 8000 m height |
| Rise time | 12.8 min at an altitude of 8000 m |
| Service ceiling billing ceiling |
10,100 m 10,300 m |
| Range at cruising speed |
850 km with 430 l fuel 1000 km with 510 l fuel |
| Duration of flight at cruising speed |
1.9 h with 430 l of fuel 2.25 h with 510 l of fuel |
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. 329.
Web links
Individual evidence
- ↑ Doug Dildy, Frans Scheve: "Meidagen" - Holland 1940. In: Fliegerrevue Extra No. 13, Möller, 2006, ISSN 0941-889X, p. 58