<!-- This article is a part of Wikipedia:WikiProject Aircraft. Please see Wikipedia:WikiProject Aircraft/page content for recommended layout. -->{{Infobox Aircraft
 |name=Nieuport 21
 |image=Image:Nieuport_21.jpg
 |caption=
 |type=Fighter
 |manufacturer=Nieuport
 |designer=
 |first flight=
 |introduced=1916
 |retired=1920s
 |status=
 |primary user=''Aéronautique Militaire''
 |more users=Russian Air Force<br>US Army Air Service<br>Finnish Air Force
 |produced=
 |number built=
 |unit cost=
 |developed from=
 |variants with their own articles=
}}
The '''Nieuport 21''' was a French single-seat, single-engine fighter used during the First World War. The aircraft was used by the French, Russian, and American air forces. After the war, the Nieuport 21 was a popular civil aircraft.

==History==
The Nieuport 21 was designed by Le Rhône 9C engine as it was originally intended as a fighter training aircraft. As the  engine was fitted with a horseshoe shaped cowling, the Nieuport 21 was often mistaken for the smaller Nieuport 11, which had a similar cowling.  However, due to the urgent requirement for fighters, it had to be taken into service as a frontline fighter. Nieuport 21s were sold to the United States (who used them as trainers) and Russia, equipped with a 110 hp Le Rhône engine. They were also used in limited numbers by the RNAS. The Nieuport 21 was license manufactured in Russia by A/O Duks.

The Finnish Air Force (the ''Whites'') captured one aircraft in Tampere in 1918. It was used until 1923.

==Operators==
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==Specifications==
{{aircraft specifications

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|plane or copter?=plane
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|ref=Suomen Ilmavoimat I 1918-27

|crew=1
|capacity=
|length main=6.0 m
|length alt= 19 ft 8 in
|span main=8.16 m
|span alt= 26 ft 9 in
|height main=2.40 m
|height alt= 7 ft 10 in
|area main=14.75 m²
|area alt= 159 ft²
|airfoil=
|empty weight main=320 kg
|empty weight alt= 704 lb
|loaded weight main= 
|loaded weight alt= 
|useful load main= kg
|useful load alt= kg
|max takeoff weight main=495 kg
|max takeoff weight alt= 1089 lb
|more general=

|engine (prop)= Le Rhône 9C
|type of prop=radial engine
|number of props=1
|power main= 60 kW
|power alt=80 hp
|power original=

|max speed main=140 km/h
|max speed alt= 76 knots, 87 mph
|cruise speed main= km/h
|cruise speed alt= knots,  mph
|stall speed main= km/h
|stall speed alt= knots,  mph
|never exceed speed main= km/h
|never exceed speed alt= knots,  mph
|range main=250 km
|range alt= 132 nm, 152 mi
|ceiling main= m
|ceiling alt= ft
|climb rate main= m/min
|climb rate alt= 
|loading main= 33.6 kg/m²
|loading alt= 6.89 lb/ft²
|thrust/weight=
|power/mass main= 0.121 W/kg
|power/mass alt=0.073 hp/lb
|more performance=

frame|right|Nieuport 21
'''Nieuport 21''' oli ensimmäisen maailmansodan aikainen puurakenteinen, kaksitasoinen, yksimoottorinen ja yksipaikkainen hävittäjälentokone. Konetta käyttivät Ranskan, Yhdysvaltojen ilmavoimat. Sodan jälkeen kone oli suosittu harrastelentokone.  

== Taustaa ==
Koneen suunnitteli Gustave Delage ja sen ensilento tapahtui 1916. Kone oli heikompitehoisella moottorilla varustettu versio Nieuport 17-hävittäjästä ja se suunniteltiin alun perin harjoitushävittäjäksi. Konetta jouduttiin kuitenkin konepulan takia käyttämään operatiivisissa tehtävissä. Nieuport 21-koneita myytiin mm. Venäjälle sekä Yhdysvaltoihin, näistä vientikoneista osa oli varustettu 110 hv:n Le Rh&ocirc;ne-moottorilla. Konetta valmistettiin Nieuportin lisäksi lisenssillä Venäjällä, valmistajana A/O Duks.

==Käyttö Suomessa==
Valkoiset saivat yhden Nieuport 21-koneen (valmistusnumero 1325) sotasaaliiksi Tampereelta huhtikuussa 1918. Kone oli käytössä tunnuksella D86/18 4. huhtikuuta 1923 tapahtuneeseen poistoon asti.

== Tekniset tiedot ==
* Kärkiväli: 8,16 m
* Pituus: 6,0 m
* Korkeus: 2,40 m
* Siipipinta-ala: 14,75 m<sup>2</sup>
* Tyhjäpaino: 320 kg 
* Lentopaino: 495 kg
* Voimalaite: Le Rh&ocirc;ne 9 C-tähtimoottori, 80 hv