Polikarpov I-16

World's first low-wing cantilever monoplane fighter with retractable landing gear to attain operational status and as such "introduced a new vogue in fighter design".[2] The I-16 was introduced in the mid-1930s and formed the backbone of the Soviet Air Force at the beginning of World War II
Skilled Soviet pilots took advantage of the Polikarpov's superior horizontal maneuverability and liked it enough to resist the switch to more modern fighters.