High Quality Content by WIKIPEDIA articles! The Yakovlev Yak-15, NATO reporting name: Feather,USAF/DOD designation Type 2) was a first-generation Soviet turbojet fighter developed by the Yakovlev design bureau (OKB) immediately after World War II. It used a reverse-engineered 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. Although nominally a combat aircraft, it mainly served to convert pilots with experience with piston-engined fighters to jets.