Arch rival to the U.S. F-86 in Korea, the MiG-15 shocked the West with its capabilities. The Soviets designed the aircraft in 1946 to answer an urgent need for a high-altitude day interceptor. It first flew in late 1947. The MiG-15 was the first Soviet jet to benefit from the British sale to Russia of the new Rolls Royce Nene and Derwent jet engines, which the Soviets immediately copied and refined. First successful jet fighter to incorporate swept wings to achieve high transonic speeds.