The Fokker D.XXI fighter was designed in 1935 for use by the Royal Netherlands
East Indies Army Air Force . As such, it was designed as an inexpensive and
small, but rugged aircraft, which had respectable performance for its time.
Entering operational use in the early years of World War II, it provided
yeoman service for both the Luchtvaartafdeling and the Finnish Air
Force, and a few were built by the El Carmolí factory before it fell into
rebel hands during the Spanish Civil War.
Design and development The Fokker D.XXI was a low-wing
monoplane with a fixed spatted undercarriage. Following standard Fokker
design practice of the period, it had a steel tube fuselage covered in large
part by fabric, with wooden cantilever wings. Power was provided by a Bristol
Mercury radial driving a three-blade two-pitch propeller. When it entered
service in 1938 it was a significant leap forward for the Dutch Army Aviation
Group, whose fighter force had until that time consisted of aging biplanes
with open cockpits. The new Fokker proved to be an extremely sturdy
aircraft capable of attaining a speed of 700 km/h in a dive.
Operational history In 1936 a few Fokker D.XXIs were used by
the Spanish Republic. Although the order by the ML-KNIL was cancelled, the
Luchtvaartafdeling placed an order of 36 aircraft, which were all delivered in
time to participate in the war against the Germans in May 1940. The Fokker
D.XXI, although much slower and more lightly armed than the Bf 109, performed
surprisingly well in dogfights, due to its maneuverability. It was also one of
the few aircraft that could follow a Stuka bomber into its dive. Nonetheless,
the numerical inferiority of the Luchtvaartafdeling compared to the
Luftwaffe resulted in the destruction of most Dutch Fokker D.XXI fighters during
the campaign. Some were captured during and after 15 May, but their fates, apart
from their capture, are unknown. The Fokker D.XXI performed better and
for much longer in the Finnish Air Force, which had acquired a number of
licence-built fighters prior to the start of the Winter War. Against the
aircraft of the Soviet Air Force, the Fokker was more evenly matched, and its
rugged design with a radial engine and fixed undercarriage made it very
suitable for Finnish conditions. Later in the war, as newer models of Soviet
fighters appeared, the Fokker D.XXI was underpowered and too lightly armed to
compete. Plans to arm the Fokkers with 20 mm cannons were dropped and only one
fighter was armed as such. Another fighter was equipped with retractable
landing gear, but due to less than anticipated performance improvement,
wasn't continued in the series. During the Continuation War the Finnish State
Aircraft Factory also built some 50 D.XXIs with the Swedish-built Pratt &
Whitney R-1535 Twin Wasp Junior as the Bristol Mercury was in short supply.
These can be identified by their longer cockpit glazing, smooth cowl, and large
ventral air intake under the cowl. The fixed undercarriage lent itself to both
unimproved runways and conversion to skis for winter use, both of which were
advantages in the Finnish theater. Several Finnish Air Force pilots became
fighter aces with the Fokker D.XXI. The top scoring Fokker ace was Jorma
Sarvanto who obtained 12 5/6 victories with the type. Many other future aces
scored at least one victory with the Fokker. The highest scoring airframe was
FK-110, with 10 victories. This aircraft survived the war and is on display at
the Central Finland Aviation Museum. Variants
D.XXI Prototype serial no FD-322
D.XXI-1 Pattern aircraft supplied to Denmark,
two built, powered by 645 hp Bristol Mercury VIS engines. Armed with 2x 8 mm
machine guns and 2x 20 mm Madsen cannon D.XXI-1
Production aircraft built at the Royal Army Aircraft Factory, ten built powered
by 830 hp Bristol Mercury VIII engines. D.XXI-2
53 Built, of which 36 were delivered to the RNLAF.
D.XXI-3 Finnish license-built D.XXI-2s. Number
built: 38 D.XXI-4
Upgraded D.XXI-3, powered by 825 hp Pratt & Whitney R-1535-SB4C-G Twin Wasp
Junior engines. Number built: 50 D.XXI-5
Upgraded D.XXI-4, powered by 920 hp Bristol Pegasus radial engines. Number
built: five Project 150
Proposed version powered by a Bristol Hercules radial piston engine. Not
built. Project 151
Proposed version powered by a Rolls-Royce Merlin piston engine. Not
built. Project 152
Proposed version powered by a Daimler-Benz DB 600H engine. Not built.
Operators Denmark
Hærens Flyvertropper received two aircraft and built ten on license.
Locally designated IIIJJydske Flyverafdeling - two. Eskadrille
Finland Finnish Air Force received seven
aircraft and built 93 on license. No. 10 Squadron, Finnish Air Force
No. 12 Squadron, Finnish Air Force No. 14 Squadron, Finnish Air Force
No. 24 Squadron, Finnish Air Force No. 26 Squadron, Finnish Air Force
No. 30 Squadron, Finnish Air Force No. 32 Squadron, Finnish Air Force
Germany Luftwaffe operated an unknown number of
captured Dutch aircraft. Netherlands
Dutch Army Aviation Group received 36 aircraft.
1 Luchtvaartregiment 1 and 2 Jachtvliegersafdeling 2
Luchtvaartregiment Spanish Republic
Spanish Republican Air Force May have completed one aircraft.
Museums Aviation Museum of Central Finland has
FR-110 on display having been restored with additional parts from FR-81 and
FR-137. Militaire Luchtvaart Museum has a
replica painted in KLu markings. Crash Foundation
Popular culture A converted North American Harvard
trainer masqueraded as a Fokker D.XXI for the Paul Verhoeven movie Soldier of
Orange. Specifications
Data from General characteristics
Crew: one Length: 8.2 m
Wingspan: 11 m Height: 2.92 m
Wing area: 16.2 m2 Empty weight: 1,594 kg
Gross weight: 1,970 kg Powerplant: 1 × Bristol Mercury VIII
9-cyl. air-cooled radial piston engine, 620 kW
Performance Maximum speed: 460 km/h
Cruising speed: 429 km/h Never exceed speed: 700 km/h
Range: 930 km Service ceiling: 11,350 m service
ceiling Time to altitude: 6,000 m in 7 min 30
sec Power/mass: 0.309 kW/kg
Armament 4 × 7.7 mm Vickers machine guns
See also Aircraft of comparable role,
configuration and era Curtiss Hawk 75
Nakajima Ki-27 Koolhoven F.K.58
Fiat G.50 Related lists
List of fighter aircraft List of aircraft of the Spanish
Republican Air Force List of aircraft of World War II
References Notes
Bibliography External links
Fokker D.XXIs to Finland Fokker D.XXI Walk-around