The Soviet Shvetsov "OKB-19" design bureau was the sole source of design for all of the Soviet government factory-produced radial engines used in its World War II aircraft, starting with the Shvetsov M-25 (itself based on the American Wright "Cyclone 9"'s design) and going on to design the 41-litre displacement Shvetsov ASh-82 fourteen cylinder radial for fighters, and the massive, 58-litre displacement Shvetsov ASh-73 eighteen-cylinder radial in 1946 - the smallest-displacement radial design from the Shvetsov OKB during the war was the indigenously designed, 8.6 litre displacement Shvetsov M-11 five cylinder radial.