This Polikarpov fighter, developed in 1934, took a lot of its design ideas from the then-revolutionary Gee-Bee racing airplane of the same period – that is, the largest engine that could be fit into the smallest airframe. Adding retractable landing gear and four rifle-caliber machine guns and you had the miniscule I-16, a staple of the Soviet air force through the early part of World War 2, almost 10,000 being manufactured.
These tough little aircraft served in other forces as well, most notably in the Chinese Guomindang, where they pitted themselves against the more nimble and far more numerous Japanese fighters of the period. How they fared is another story.