The Junkers J 21 (manufacturer's sales designations T 21 and H 21) was a reconnaissance aircraft designed in

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

in the early 1920s and produced in the

Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...

at the Junkers plant at Fili for use by the

Soviet Air Force The Soviet Air Forces ( rus, Военно-воздушные силы, r=Voyenno-vozdushnyye sily, VVS; literally "Military Air Forces") were one of the air forces of the Soviet Union. The other was the Soviet Air Defence Forces. The Air Forces ...

Design and development

The J 21 was an all-metal,

parasol-wing A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes. A monoplane has inherently the highest efficiency and lowest drag of any wing con ...

monoplane A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes. A monoplane has inherently the highest efficiency and lowest drag of any wing con ...

of conventional configuration and fixed, tailskid undercarriage. The pilot and observer sat in tandem, open cockpits. Two prototypes were constructed at the Junkers factory in Dessau, the second with a wing of reduced area. Despite the fact that the prototypes were unable to attain the performance that had been specified by the Soviets, series production commenced at Fili in August 1923 where it was known as the Ju 21 (Юнкерс Ю 21 in Cyrillic). The production version differed from the prototypes in having a

BMW IV The BMW IV was a six-cylinder, water-cooled inline aircraft engine built in Germany in the 1920s. Power was in the 180 kW (250 hp) range. World record On 17 June 1919 Franz Zeno Diemer flew a DFW F37, powered by a BMW IV engine to ...

engine in place of the

BMW III BMW IIIa was an inline six-cylinder SOHC valvetrain, water-cooled aircraft engine, the first-ever engine produced by Bayerische Flugzeugwerke AG, who, at the time, were exclusively an aircraft engine manufacturer. Its success laid the foundatio ...

originally fitted, and carried

machine gun A machine gun is a fully automatic, rifled autoloading firearm designed for sustained direct fire with rifle cartridges. Other automatic firearms such as automatic shotguns and automatic rifles (including assault rifles and battle rifles) ar ...

armament for both the pilot and observer. Sluggish performance led to a few examples being fitted with L2 and L5 engines, but these provided little improvement. With performance only marginally better than the

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

-vintage de Havilland DH-9A that it had been purchased to replace, the Ju 21 was itself soon replaced by newly built DH-9As built under license as the

Polikarpov R-1 The Airco DH.9A was a British single-engined light bomber designed and first used shortly before the end of the First World War. It was a development of the unsuccessful Airco DH.9 bomber, featuring a strengthened structure and, crucially, repl ...

. The type was also evaluated by the ''

Reichswehr ''Reichswehr'' () was the official name of the German armed forces during the Weimar Republic and the first years of the Third Reich. After Germany was defeated in World War I, the Imperial German Army () was dissolved in order to be reshape ...

''s clandestine

training Training is teaching, or developing in oneself or others, any skills and knowledge or fitness that relate to specific useful competencies. Training has specific goals of improving one's capability, capacity, productivity and performance. I ...

school at

Lipetsk Lipetsk ( rus, links=no, Липецк, p=ˈlʲipʲɪtsk), also romanized as Lipeck, is a city and the administrative center of Lipetsk Oblast, Russia, located on the banks of the Voronezh River in the Don basin, southeast of Moscow. Populat ...

, but it was rejected due to its poor performance and the Heinkel HD 17 purchased instead.

Variants

*J 22 (T 22): single-seat fighter version, very similar to the J 21 but with its wing lowered almost to the top of the fuselage to reduce drag, the pilot's cockpit moved back further than the gunner's position on the J 21 and a more rounded rudder. First of two flew 30 November 1923. No production so no sales or Russian letter prefix. *J 28: two-seat fighter version of J 21 with a 400 hp BMW VI engine. No production.

Operators

; *

Imperial Iranian Air Force The history of the Iranian Air Force, currently known as the Islamic Republic of Iran Air Force, can be divided into two phases—before the Islamic Revolution, and after it. Imperial era The Imperial Iranian Air Force (IIAF) was a branch ...

; *

Specifications (first prototype)

References

External links