First, a TEM trivia question:

What was Fokker's "last fighter?"
(Answer at the end of the article)

On July 21, 1919, a new airplane-manufacturing firm, N.V. Nederlandsche Vliegtuigenfabriek, was established at Amsterdam in the Netherlands. Its founder and managing director, one A.H.G. (Anthony) Fokker, was the same Anthony Fokker who had built many of Germany's premier fighter planes used in the recently ended World War. For obvious reasons his name was not included in the company name, but it wasn't long before the company unofficially became known as Fokker Aviation. Beginning with the large quantities of aircraft and accessories that Fokker had smuggled across the border, the company became the largest aircraft manufacturer in the world by the late 1920s. Besides building civilian airliners, Fokker, starting with upgraded versions of his famous D.VII, designed and produced military aircraft for the Dutch air services and for export abroad.

Design

On November 14, 1934, in response to a specification issued by Luchtvaartafedling (Air Division) of the Koninklijk Nederlands Indisch Leger (Royal Netherlands Indies Army), for a new fighter, the South Amsterdam factory of the Fokker company tendered a design for a monoplane with the then advanced features of a low wing position and an enclosed cockpit. Flexibility was built-in as the aircraft could be powered with either a. liquid-cooled or air-cooled engine. Early in 1935, the LVA contracted with Fokker for one prototype which first flew on March 27 1936, and was designated the Fokker D.XXI (the latest Fokker fighter in the "D" series which ran in sequence beginning with Fokker's World War One fighter designs).

The D.XXI, designed by a team led by Dr. Erich Schatzki, featured conventional Fokker mixed construction (wooden wings and a welded-steel fuselage covered with fabric, aluminum and duraluminum) and a fixed landing gear. Powered by an air-cooled radial engine, the 645 hp Bristol Mercury VI-S, and armed with four 7.92 Browning FN machine guns with 300 rpg (two in the fuselage and two in the wings), the prototype reached a maximum speed of 245 mph. However, the Dutch government decided to order only bombers for the KNIL. The home-based Luchtvaartafedling (Air Division or LVA) rejected the plane in favor of "luchtkruisers" (destroyers), and a competing design by Schatzki, who was now working for a rival Dutch company, the Koolhoven FK-58. This aircraft had been offered to the LVA with the claim that its performance was much superior to the D.XXI.

While D.XXI remained in limbo in the Netherlands, the Fokker company aggressively marketed the design to foreign air forces who had in the past ordered and built its products, such as the C.V. Finland and Denmark were the first to show interest. Two D.XXIs (designated the D.XXI-1) were ordered for the Danish Hoerens Flyvertropper (Army Aviation Troops) in 1936 (and delivered in 1938), and the Danish government purchased a license to build ten more at the Hoerens Flyvertroppers Voerksteder (Army Aviation Troops' Workshops). The D.XXI- I featured the same engine as the prototype but was armed with two fuselage mounted 7.9 mm machine guns and two 20 mm Madsen cannon mounted under the wings. On November 18, 1936, seven D.XXIs were purchased by the Finnish government who later acquired a manufacturing license to build 35 more at the State Aircraft Factory ("Valtion Lentokonetehdas" or VL) at Tampere. The Finnish D.XXIs, designated D.XXI-2, were powered by license-built 760 hp Bristol Mercury VIIs and, like the prototype, were armed with four 7.9 mm FN-Browning M-36 machine guns, in the wings and fuselage.

Spanish CIvil War

With the outbreak of the Spanish Civil War the Spanish Republican Government also acquired manufacturing rights to the D.XXI. Production was begun by Hispano Aviacion at Guadalajara and later moved to La Rabasa, near Alicante. Assembly was to be at San Vincente del Raspieg, also near Alicante. Although 50 fuselages and 25 sets of wings had been built, no aircraft were completed by the time the factory was overrun by the Nationalists. One aircraft, fitted with a Russian M-25, was actually flown by the Nationalists, but the remaining parts were scrapped, except for the landing gear sets which were used for the Hispano HS-42 trainer.

[See For Whom the Bell Tolls: Loyalist OB, Optional Additional Aircraft, May 1939, add at Barcelona (33:3625), 1x D.XXI 5F4 1/61

The rise in international tension caused the Dutch Government to fund the expansion of the LVA. The LVA reevaluated the D.XXI, testing the version intended for Finland, with favorable results and, as the FK-58 failed to achieve flight status until September 1938, 36 D.XXIs were ordered. Powered with British-built Mercury VIII engines and also designated D.XXI-2, the Dutch models had all four machine guns mounted in the wings. The last of the production aircraft was delivered on September 8, 1939.

[See Fall of France: presumably included in the Netherlands Air OB in the 1x Mxd 5F3 1/6.]

The Koolhoven F.K.58 was also placed into production but as a result of an order for 50 aircraft by the French government for service in French colonial territories. Eighteen saw,action in May 1940 flown by expatriate Polish pilots on factory defense with various Patrouilles de Protection. The "destroyer" envisioned by the Dutch government emerged as the twin-boomed, twin-engined Fokker G. 1, originally built as a private venture fighter/fighter-bomber/ reconnaissance aircraft. Twenty-three saw combat in May 1940. As with the D.XXI, both Finland and Denmark placed orders for export versions of the G. I but none were ever delivered.

WWII Service

Eight D.XXI-1s were serving with 2.Eskadrille of the Hoerens Flyvertropper at Vaerlose Airfield at Copenhagen when the Germans overran Denmark on April 9, 1940. Hauptmann Wolfgang Falck, a future night fighter ace, shot down one while it was attempting to take off; Bf110s of 1./ZG1 strafed and damaged three others on the ground. The survivors, seven in number, were placed in storage and seized by the Wehrmacht on August 29, 1943.

The LVA had 29 operational D.XXI-2s when Germany invaded the Netherlands on May 10, 1940: 11 with Ie JaVA at De Kooy, 10 with 2e JaVA at Schipol; and 8 with 5e JaVA at Ypenburg (JaVA = Jachtvliegtuigafdelingen or fighter squadron). Despite facing overwhelming odds and being 100km/h slower than the Messerschmidt Bf109E, the D.XXI put up a fight. The D.XXI's most notable success came on May 10th when they shot down 37 out of 55 Ju52/3m of KGrzbV 9 which were attempting to fly the air-landing troops of 22. Infinterie-Division (LL) into Amsterdam. The most notable individual success by a D.XXI pilot was by Sgt. J. Roos, who, after being attacked by three Bf109s and suffering severe damage, then attacked and destroyed two Bf110s, one by gunfire and one by ramming. He was then hit by friendly AA and forced to bail out. Only 8 or 9 D.XXIs remained operational when the Dutch Government capitulated on May 14, 1940. In addition to the 37 destroyed transports, D.XXIs had 15 confirmed and 17 claimed victories over Luftwaffe fighters and bombers.

It was in Finland where the D.XXI first saw combat, served in the largest numbers and achieved its greatest successes. When the Winter War began on November 30, 1939, 36 were serving with HLeLV 24 ("Havittajalentolaivue," fighter squadron) of the Finnish Air Force (Ilmavoimat). Despite its obsolescence, the D.XXI could still break-off combat because of its high diving speed and was one of the stars of that war.

By March 12 1940, the date Finland sued for peace, HLeLV 24 had the most aces of the Ilmavoiniat, with Captain Jorma Savento leading with 13 victories. Only 29 D.XXIs remained, as twelve had been lost (but only six in combat). The D.XXI had been responsible both for Finland's first aerial victory (an SB-2 shot down on December 1 1939, by Lt. Jaakko Vuorela, who claimed the first victory, just ahead of Lt. Eino Luukkanen, later to become Finland's third top-scoring ace) and its first aerial casualty (to friendly antiaircraft fire). Finnish pilots nick-named their D.XXIs "Ukkomokkeri" or "Isamokkeri" ("Old Man Mokker")

[See A Winter War: Finnish Air Force OB, Sep 1939: 1x D.XXI 3F4 0/6.1

After the end of hostilities, HLeLV 24 re-equipped with the Brewster 239 (the export version of the USN's F2A Buffalo), and the remaining D.XXIs were overhauled by VL and then assigned to newly formed squadrons: HLeLv 30 and HeLeLV 32. Production continued in Finland with fifty more being produced in 1941. However, all Mercury engines were needed for the Bristol Blenheim Is and IVs serving with the Finnish Air Force, so VL redesigned the D.XXI to take the American 825 hp Pratt-Whitney R-1535 Twin Wasp radial air-cooled engine (eighty of these had been imported via Sweden in 1940). The size of the new engine meant the fuselage guns had to be moved to the wings, and the size of the vertical tail services had to be increased. In addition, the glazing of the rear of the cockpit was extended to improve the pilot's vision aft. With a heavier engine, the Twin Wasp D.XXIs were slightly slower and less maneuverable than their Mercury counterparts. As a field modification, Finnish D.XXIs often were equipped with skis.

Finnish Continuation War

When Finland joined the attack on Russia in the "Continuation War" in June 1941, the Finnish Air Force had 17 Mercury D.XXIs and 19 Twin-Wasp D.XXIs serving with HLeLv 32. Additional Mercury D.XXIs were with one flight of HLeLv 30 and with one flight of TLeLv 12.

Again the first Finnish aerial victory of this conflict went to the D.XXI when HeLeLv 32 shot down 2 DB-3s on June 25 1941. HeLeLv 32 re-equipped with Curtiss Hawk 75s and the D.XXIs were relegated to tactical reconnaissance duties with TLeLv 12 ("Tiedustelulaivue" or ground liaison squadron) and TLeLv 14. Despite primarily serving in the reconnaissance and training roles, D.XXIs still claimed 60 aerial victories to go with the 127 victories gained in the Winter War. In 1944, VL built five more D.XXIs from spares which were powered by 920 hp Bristol Pegasus X engines, and also constructed an experimental model fitted with retractable landing gear. 36 were still in service on January 1, 1945. The last left active service in 1949.

[See Fire in the East: Finnish Air Force OB, Initial: 1x D.XXI 3F4 0/6; plus one received Nov 141.]

Anthony Fokker never lived to see the success of his penultimate fighter, dying at age 49 on December 23, 1939. His company finally went bankrupt in 1996. Yet, despite its small numbers and obsolescence, Fokker's penultimate fighter, like its ancestors in the First World War, forged an enviable record in the early years of the Second World War, especially in Finland during the Winter War, going up against the modern, faster aircraft of the air forces of two great dictatorships. Of the 209 or so D.XXIs ordered, 149 were actually built for three countries (of the four who placed orders); and the air forces of only two saw significant aerial combat in World War Two. Nevertheless, if only for its successful service with the Ilmavoimat in the David and Goliath struggles against the Soviet Union, the D.XXI deserves to be remembered as one of the notable aircraft of World War Two.

Performance, D.XXI
Spec	Netherlands	Finland
Engine:	825 hp Bristol Mercury VIII 9-cylinder radial, air- cooled	1050 hp Pratt & Whitney R-1535 Twin Wasp Junior SB4-G 14-cylinder radial air-cooled
Maximum speed:	286 mph @ 16,730 ft	272 mph @ 9,000 ft
Cruising speed:	240 mph	221 mph
Climb:	1.15 min to 3280 ft 3.4 min to 9840 ft 7.5 min to 19,685 ft	1.4 min to 3280 ft 4.5 min to 9840 ft
Service ceiling:	31,600 ft	29,520 ft
Range:	590 miles	550 miles
Weight:	3197 lb empty 4519 lb loaded	3380 lb empty 4820 lb loaded
Armament:	4x 7.9mm FN-Browning MG with 300 rpg	4x 7.92 FN-Browning M-36 machine gun

Production

D.XXI-1 (1 prototype, 2 for Denmark)
D.XXI-2 (7 for Finland, 36 for the Netherlands, including I D.XXI-El, experimental model with increased wing dihedral)
DXXI (10 license-built in Denmark)
D.XXI-3 (38 license-built in Finland)
DXXI-4 (50 license-built in Finland)
DXXI-5 (5 license-built in Finland)
Total 149 (plus 50 to be license-built in Spain)

Selected Bibliography

Eberspacher, Warren; Fokker D.XXI-1; St. Paul MN: Phalanx Publishing Co., Ltd.
Green, William: War Planes of the Second World War Fighters, Volume One; Garden City NY: Doubleday and Company, Inc., 1963.
Green, William: War Planes of the Second World War Fighters, Volume Three; Garden City NY: Doubleday and Company, Inc., 1964.
"The 'Halfway-House' Fokker," Air Enthusiast August 1971.
Information from Vesa Honkasaari
Hooten, E. R.; Phoenix Triumphant the Rise of the Luftwaffe, London: Arms & Armour Press, 1994.
Karnphuis, G. H.; "The Fokker D.XXI," in Aircraft in Profile, Volume 3; Martin C. Windrow, ed.; Garden City NY: Doubleday and Company, Inc., 1968.
Keskinen, Kalevi and Kari Stenman; Finnish Air Force 1939 -1945; Carrollton TX: Squadron\Signal Publications, Inc., 1998.
"The Mower - Fokker's Final Fighter," Air International Vol 7 No 4 (October 1974).
Shores, Christopher F.; Finnish Air Force 1918-1968; New York: Arco Publishing Company, Inc., 1969.
[Plus some really neat stuff I got off the Internet, including the history of the Fokker company as found on the Fokker bankruptcy trustees' home page.]

Fokker's Last Fighter