D.XXIs to Finland Fokker Development The Dutch East-Indian Army ordered a single-seat monoplane from the Fokker factory on November 14, 1934 to replace the Curtiss P-6 Hawk aircraft. The factory stressed simple design with a fixed landing gear. 3D wireframe picture of the Fokker D.XXI 650 hp Rolls Royce Kestrel IV was initially selected to power the fighter, but it was replaced soon with the 645 hp Bristol Mercury VI-S nine cylinder radial engine (on the right). The first three Finnish series were equipped with the 840 hp Bristol, PZL or Tampella Mercury VII 9-cylinder air-cooled radial engine. The Bristol Mercury engine, which turned out to give better performance for the Fokker than the Twin Wasp engine. Finnish series IV and V had the 825 hp Pratt&Whitney R-1535 Twin Wasp Junior SB4-C or G 14-cylinder air-cooled twin radial engine. The Mercury Fokkers (FRm) had a Ratier propeller and the Wasp Fokkers (FRw) a Hamilton Standard propeller. For training the Air Force used wooden propellers. The prototype was ready in early 1936 and it was delivered to Welschap airfield close to Eindhoven, where Fokker test pilot Emil Meinecke flew the first flight on the 27th of February 1936. In 1937 the Dutch government ordered 36 Fokkers equipped with the Mercury VIII engine. In addition to the Netherlands, Finland and Denmark would order the aircraft. Fokker D.XXI prototype FD-332 at Schipol airfield 1936 during "Wool Tuft" tests. Notice the white dots on the rear fuselage surface. The strings were used to verify the airflow over the fuselage and tail. Rudder flutter had been experienced and so tin weights had to be installed. The canopy has been removed for tests. Finland is the first export customer The Finnish Air Force had already operated the Fokker D-10 and the Fokker CVE and CVD. The CX model was used as a dive bomber. The Air Force had continuous connections with the Fokker factory in the 1930's. The Fokker D.XXI was half the price of the German Messerschmitt Me-109. When the Fokker D.XXI flew the first fligh, Me-109, Heinkel He-112, Hurricane and Spitfire had already flown with much higher max speeds. Fokker D.XXI had a fixed gear and an underpowered engine for interceptions, it lacked armour and the effectiveness of the weapons was questionable. The radios were limited in the beginning and the max level speed was only 420 - 440 km/h. Finland was the first export customer for the Fokker D.XXI and signed a deal for seven aircraft and license for 14 more on the 18th of November 1937. Fokker D.XXI production in Amsterdam The Fokker factory tried the so-called E-model wing with FR-76 in 1937. The wingtip was narrower and it had been "twisted" upwards from the main gear. Flight tests were disappointing and the regular wing was reattached. FR-76 with the E-model wing in the Netherlands, 1937. The max. sea level speed for II Series Fokkers was (performance for the Twin Wasp Fokker from Series IV in parenthesis) 342 km/h (354), at 2000 m 370 km/h (375) and at 5000 m 418 km/h (350). Climb to  3000 m (10.000 ft) was 3 min 27 sec (5 min 02 sec) and to 5000 m (17.000 ft) 6 min 23 sec (10 min 12 sec). Service ceiling 10100 m (9600 m) and range 950 km (800 km). It is easy to judge that the Twin Wasp Fokker had a slightly better sea level performance, but clearly lost at altitude. The Mercury Fokkers were armed with two 7,7 mm Vickers machine guns in the forward fuselage and one in each wing whereas the Wasp Fokkers didn't have fuselage weapons because of the twin radial engine. They were equipped with two 7,7 mm Browning machine guns in each wing. FR-76 had two 20 mm Oerlikon cannons, but experiences in the Winter War were negative and the aircraft was re-equipped with machine guns. The gunsight for the Fokkers was the optical tube-sight Goertz or the reflector sight Revi 3C or D. FR-76 20 mm Oerlikon cannon.   Go to Fokker D.XXIs to Finland, page 2 Home Latest Topic | Air Warfare | Conferences/Air Shows | Fighter Tactics | Fighter Aircraft | Missiles | Fighter Aviation Topic | Fighter History | Warbirds | Magazines | Current News | Links | Physiology | Photo Gallery | Bibliography | SIIVET - Wings | What's New J Lindberg. Copyright © 1997-2006 Fighter Tactics Academy. All rights reserved. Revised: tammikuu 01, 2006.