The Polikarpov I-15 was a Soviet biplane fighter aircraft that emerged in the 1930s.
It earned the nickname Chaika due to its distinctive gull-shaped upper wings.
The aircraft was utilised extensively by the Soviet Air Force and, alongside the Polikarpov I-16 monoplane, served as one of the primary fighters for the Spanish Republicans during the Spanish Civil War, where it was referred to as Chato (snub-nose).
