The Nieuport 21 (or Nieuport XXI C.1 in contemporary sources) was a French single-seat, single-engine fighter aircraft used during World War I. The aircraft was used by the French, Russian, British and American air forces. After the war, the Nieuport 21 was a popular civil aircraft. Design and development The Nieuport 21 was designed by Gustave Delage and it made its maiden flight in 1916. While it had a similar airframe to the Nieuport 17, it was equipped with a less powerful Le Rhône 9C engine as it was originally intended as a long range escort fighter. As the engine was fitted with a horseshoe shaped cowling, the Nieuport 21 was often mistaken for the slightly smaller Nieuport 11, which used the same cowling. Operational history The Nieuport 21 served alongside the more powerful Nieuport 17, where its lower weight helped boost its already impressive climb rate. Although initially intended as a bomber escort, this role was abandoned when the bombers were withdrawn from daylight operations. Large numbers were also built for training duties. Nieuport 21s were sold to Russia, and to the United States for use as trainers. The Nieuport 21 was license manufactured in Russia by Dux Factory. Examples were also used in limited numbers by the Royal Naval Air Service. A small number were used by a number of air arms in the early post war period, including the Finnish Air Force (the Whites) which had captured a Russian aircraft in Tampere in 1918 and which was used until 1923. The French Navy used one example for carrier trials in 1919 and 1920. Due to its similarity to the Nieuport 11, many operated by air forces post-war have been misidentified in the past as Nieuport 11s, few of which survived that long. Operators Argentine Navy Brazilian Air Force Estonian Air Force - Postwar Armee de l'Air French Navy Finnish Air Force Finnish Socialist Workers' Republic Red Guards (ex-Russian examples) Luchtvaartafdeling - operated 5 Nieuport 21s as 80 HP Nieuports. Portuguese Air Force Romanian Air Corps Imperial Russian Air Service Soviet Air Forces operated ex-Imperial Russian Air Service. Royal Thai Air Force Ukrainian People's Republic Air Fleet Royal Naval Air Service Five aircraft only. United States Army Air Service Specifications See also References Notes Bibliography 1910s French fighter aircraft 021 Sesquiplanes Single-engined tractor aircraft Rotary-engined aircraft 1910s French military trainer aircraft Aircraft first flown in 1916