The stubby Polikarpov I-16 was without a doubt one of the most revolutionary designs of pre-war aviation, being the first monoplane fighter with a retractable undercarriage. Part of its success lay in its M-25 engine which was based on the US Wright Cyclone, thanks to this the I-16 could boast an impressive speed for its time as well as great maneuvrability in the hands of a good pilot. It also sported an impressive armament of two cannon and two machine guns and thus packed a bigger punch than its contemporaries. The I-16 fought with distinction in Spain where it was nicknamed Rata (Rat) as well as against Finland but by the time of the German invasion was totally outclassed and suffered heavily at the hands of the more advanced Luftwaffe fighters (some were even used for ramming attacks). In spite of this, the I-16 was an excellent example of what the Soviet aviation industry was capable of and a taste of things to come in the near future.

The prototype TsKB-12 first flew on 31 December 1933 and was shown to the public during the May Day fly-by of 1935. Variants included the I-16 Type 4 with the uprated M-25 engine, and the I-16 Type 17 and Type 24 with more powerful armament configurations. The I-16 Type 18 introduced the supercharged M-62 engine which was later replaced by the M-63 in the I-16 beginning with the Type 24. Many of these aircraft could also be configured with skis for use in artic conditions.