Unknown

The Polikarpov Unknown was an experimental fighter prototype developed in the late 1930s at the Soviet Union’s central aviation design bureau. Conceived by Nikolai Polikarpov as a response to the rapid advances in monoplane speed and maneuverability, the aircraft combined an all‑metal stressed‑skin wing with a mixed‑construction fuselage to keep weight low while retaining structural strength. Powered by a 1,100‑horsepower Shvetsov M-100 radial engine, the Unknown achieved a maximum speed of 560 km/h and a service ceiling of 10,500 meters, figures that rivaled contemporary Western designs such as the Messerschmitt Bf 109. Its armament layout included two synchronized 20 mm cannons and two wing‑mounted 7.62 mm machine guns, providing a versatile mixture of firepower for both air‑to‑air and ground‑attack roles. Although the prototype demonstrated impressive performance, development was halted in 1940 due to shifting Soviet priorities toward mass‑production aircraft like the I‑16 and Yak‑1, and because of resource constraints. Nevertheless, the Unknown contributed valuable aerodynamic data and influenced later Polikarpov projects, marking a transitional step that helped the USSR close the technological gap with Western powers on the eve of World II.