The Yakovlev Yak-15 (Russian: Яковлев Як-15) was a first-generation Soviet turbojet fighter developed by Yakovlev OKB during World War II. It used a German Junkers Jumo 004 engine. Along with the Swedish Saab 21R, it was one of only two jets to be successfully converted from a piston-powered aircraft and enter production. 280 aircraft were built in 1947. Although nominally a fighter, it was mainly used to qualify piston-engine-experienced pilots to fly jets.