The Heinkel HD 21 was a trainer built 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 ...

during the 1920s. It was a conventional

single-bay A biplane is a fixed-wing aircraft with two main wings stacked one above the other. The first powered, controlled aeroplane to fly, the Wright Flyer, used a biplane wing arrangement, as did many aircraft in the early years of aviation. While a ...

biplane A biplane is a fixed-wing aircraft with two main wings stacked one above the other. The first powered, controlled aeroplane to fly, the Wright Flyer, used a biplane wing arrangement, as did many aircraft in the early years of aviation. While ...

with staggered wings braced with N-type

interplane strut In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of strut, which act in ...

s. The main units of the fixed, tailskid undercarriage were linked by a cross-axle, and the aircraft had three open

cockpit A cockpit or flight deck is the area, usually near the front of an aircraft or spacecraft, from which a Pilot in command, pilot controls the aircraft. The cockpit of an aircraft contains flight instruments on an instrument panel, and the ...

s in tandem, although one of these was typically faired over. The HD 29 of 1925 was essentially similar, but was purely a two-seater. One HD 21 (registered ''SE-ACY'') was flown as an

air ambulance Air medical services is a comprehensive term covering the use of air transportation, aeroplane or helicopter, to move patients to and from healthcare facilities and accident scenes. Personnel provide comprehensive prehospital and emergency and cri ...

by Carl Gustaf von Rosen for the

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during the Italian invasion of Abyssinia in 1935. Others were flown 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 reshaped ...

'' at the clandestine aviation training facility in

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. Populatio ...

Specifications

References

* * {{Heinkel aircraft 1920s German civil trainer aircraft HD 21 Aircraft first flown in 1924