Koolhoven F.K.55

Single-Seat, Single-Engine Prototype Fighter Aircraft

Netherlands | 1938

"Only one example of the Dutch Koolhoven F.K.55 fighter was ever completed before the program was cancelled in full prior to World War 2."

Authored By: Staff Writer | Last Edited: 05/10/2018 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site; No A.I. was used in the generation of this content.

Prior to World War 2 (1939-1945) the Dutch held a respectable aero industry that produced a few notable types of local design. The Koolhoven F.K.55 was a prototype developed along the lines of a high-speed fighter and appeared during the latter half of the 1930s. The line ended with a sole example being built, its first flight held on June 30th, 1938, and the program terminated before the end of the year.

Its design, begun in 1937, was one of a sleek all-modern fighter with the cockpit set forward of the wing mainplanes and the mainplanes shifted just ahead of midships (and shoulder-mounted). Wingtips were rounded and the appendages straight in appearance. The tail unit was conventional with a single fin and a pair of horizontal planes. Construction was mixed, composed of metal and wood. A "tail dragger" undercarriage was featured. The engine of choice became a Lorraine 12Hrs "Petrel" V-12 of 860 horsepower driving a pair of two-bladed propeller assemblies at the nose in contra-rotating fashion. Due to the placement of the cockpit, well forward in the fuselage, the engine was installed aft of the pilot (as in the famous Bell P-39 "AiraCobra" fighter detailed elsewhere on this site).

The completed aircraft was made ready for its first flight in the early part of 1938 and has all of the appearance required of a high-performance aircraft. A fixed undercarriage greeted this monumental moment for the design with the intention that a retractable system be instituted later in development. However, in practice, the design proved lacking in the power necessary for the role - the 860 horsepower produced for the engine was just take-off power. Underpowered and costly to revise, this aircraft endeavor was eventually abandoned by Koolhoven and fell to the pages of military aviation history. Engineers pushed for the installation of a Lorraine "Sterna" supercharged engine of 1,200 horsepower to no avail.

As designed, the F.K.55 sported an maximum speed of 317 miles per hour, a cruising speed nearing 280 miles per hour, a range out to 530 miles and a rate-of-climb of 2,580 feet-per-minute (all figures estimated by Koolhoven). Its proposed armament scheme was to fit a 20mm cannon firing through the propeller hub and 4 x .303 machines guns, two installed in each wing. The P-39 fielded similar armament though a more potent 37mm autocannon in the nose. Its performance was much better as well: a maximum speed of 375 mph was seen in the Q-models. Like the F.K.55, it first flew in 1938 and went on to have a strong war record in the subsequent global conflict.

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Power & Performance
Those special qualities that separate one aircraft design from another. Performance specifications presented assume optimal operating conditions for the Koolhoven F.K.55 Single-Seat, Single-Engine Prototype Fighter Aircraft.

1 x Lorraine Petrel 12Hrs 12-cylinder Vee engine developing 860 horsepower.
Propulsion

317 mph
510 kph | 275 kts
Max Speed

528 miles
850 km | 459 nm
Operational Range

2,580 ft/min
786 m/min
Rate-of-Climb

Structure
The nose-to-tail, wingtip-to-wingtip physical qualities of the Koolhoven F.K.55 Single-Seat, Single-Engine Prototype Fighter Aircraft.

1
(MANNED)
Crew

30.3 ft
9.25 m
O/A Length

31.5 ft
(9.60 m)
O/A Width

8.5 ft
(2.60 m)
O/A Height

3,527 lb
(1,600 kg)
Empty Weight

4,850 lb
(2,200 kg)
MTOW

Armament
Available supported armament and special-mission equipment featured in the design of the Koolhoven F.K.55 Single-Seat, Single-Engine Prototype Fighter Aircraft .

PROPOSED:
1 x 20mm cannon firing through propeller hub
4 x 7.7mm (0.303) machine guns in wings

Variants
Notable series variants as part of the Koolhoven F.K.55 family line.

F.K.55 - Base Series Designation; single prototype completed in 1938.

Operators
Global customers who have evaluated and/or operated the Koolhoven F.K.55. Nations are displayed by flag, each linked to their respective national aircraft listing.

Total Production: 1 Units
Contractor(s): Koolhoven - Netherlands

[ Netherlands (cancelled) ]

1 / 1

Image from the Public Domain.

Going Further...
The Koolhoven F.K.55 Single-Seat, Single-Engine Prototype Fighter Aircraft appears in the following collections:

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