The Yakovlev Yak-9 was a single-engine fighter aircraft used by the Soviet Union in World War II and after. Fundamentally a lighter development of the Yak-7 with the same armament, it arrived at the front at the end of 1942. The Yak-9 had a lowered rear fuselage decking and all-around vision canopy. Its lighter airframe gave the new fighter a flexibility that previous models had lacked. The Yak-9 was the most mass-produced Soviet fighter of all time.