Fokker D.XXI

https://en.wikipedia.org/wiki/Fokker_D.XXI

The Fokker D.XXI fighter was designed in 1935 by Dutch aircraft manufacturer
Fokker in response to requirements laid out by the Royal Netherlands East Indies
Army Air Force (Militaire Luchtvaart van het Koninklijk Nederlands-Indisch
Leger, ML-KNIL). It has the distinction of being the last fighter aircraft to be
developed by Fokker.

The D.XXI was designed as an inexpensive, rugged, and compact fighter aircraft
that would possess respectable performance for its era. Entering operational use
in the early years of the Second World War, it provided yeoman service for both
the Luchtvaartafdeling (Dutch Army Aviation Group) and the Finnish Air Force.
Additionally, a few examples were constructed by the El Carmolí factory before
it fell into rebel hands during the Spanish Civil War. Following the invasion
and occupation of the Netherlands in May 1940, several captured Dutch D.XXIs
were subsequently placed into service with the Luftwaffe.

The Fokker D.XXI was a low-wing monoplane fighter aircraft. Following standard
Fokker design practice of the period, it featured a welded steel tube fuselage
that was largely covered by fabric, including the flight control surfaces;
element forward of the trailing edges of the wings were covered by detachable
aluminum panels instead. The wings were of a wooden construction, being composed
of two box spars attached to ribs made of plywood. The aircraft was outfitted
with a fixed spatted undercarriage with cantilever legs; braking was provided by
independently-operated pedals using compress air.

The cockpit of the D.XXI was fully enclosed by a plexiglass hood featuring large
sliding sections, and was entirely jettisonable in an emergency situation to
enable pilots to bail out. Pilots were protected against turnover injuries by
means of a pylon built into the structure of the aircraft set behind the seat.
Fuel was housed in a 77-gallon tank located aft of the engine, wing-mounted
auxiliary fuel tanks could also be installed. The main armament consisted of two
pairs of 7.92mm M36 FN-Browning machine guns, two being housed within the wings
and the other pair within the forward fuselage, requiring the latter to shoot
through the propeller blades; guns installed within the fuselage carried 500
rounds each while wing-mounted guns had 300 rounds each.

Upon its entry to service in 1938, the D.XXI represented 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 quickly
proved to be an extremely sturdy aircraft, being capable of attaining a speed of
700 km/h in a dive.


Role
Fighter

Manufacturer
Fokker

Designer
Erich Schatzki

First flight
27 March 1936

Retired
1948

Status
retired

Primary users
Finnish Air Force
Dutch Air Force
Danish Air Force

Number built
148

The Fokker D.XXI was first used in combat by the Finnish Air Force during the
1939-1940 Winter War between the Soviet Union and Finland. Upon the war's
outbreak, a total of 41 aircraft were in Finnish service, all of which being
powered by the Mercury VIII engine. On 1 December 1939, the D.XXI achieved its
first victory with the shooting down of a Soviet Tupolev SB. 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 well suited
for Finnish conditions. The performance of the Finnish D.XXI allegedly won the
admiration of many Soviet pilots.

The conflict between Finland and the Soviet Union was resumed in the
Continuation War (1941–44), the D.XXI was again a key element of the Finnish Air
Force. During the first air battle, six Mercury-engined D.XXIs shot down a pair
of Soviet Ilyushin DB-3 bombers. Several Finnish Air Force pilots became fighter
aces with the Fokker D.XXI. The top scoring Fokker ace, Jorma Sarvanto, obtained
12 5/6 victories with the type; many other future aces also scored at least one
victory with the Fokker. The highest scoring airframe was FR-110, achieving 10
victories; this aircraft survived the war and is on display at the Central
Finland Aviation Museum. Finland continued to operate their D.XXIs until 1949,
and classified them as surplus to requirements in 1952.

The D.XXI, although much slower and more lightly armed than the Bf 109,
performed surprisingly well in combat 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 D.XXI fighters during the
campaign. Some were captured during and after 15 May, but their fates, apart
from their capture, are unknown.

Specifications (D.XXI - Finland - Mercury)

General characteristics
Crew: one
Length: 8.2 m (26 ft 11 in)
Wingspan: 11 m (36 ft 1 in)
Height: 2.92 m (9 ft 7 in)
Wing area: 16.2 m2 (174 sq ft)
Empty weight: 1,594 kg (3,514 lb)
Gross weight: 1,970 kg (4,343 lb)
Powerplant: 1 × Bristol Mercury VIII 9-cyl. air-cooled radial piston engine, 620
kW (830 hp)

Performance
Maximum speed: 460 km/h (286 mph; 248 kn)
Cruise speed: 429 km/h (267 mph; 232 kn)
Never exceed speed: 700 km/h (435 mph; 378 kn)
Range: 930 km (578 mi; 502 nmi)
Service ceiling: 11,350 m (37,240 ft) service ceiling
Time to altitude: 6,000 m (19,685 ft 0 in) in 7 min 30 sec
Power/mass: 0.309 kW/kg (0.188 hp/lb)

Armament

4 × 7.7 mm (0.303 in) Vickers machine guns






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