The Mikoyan-Gurevich MiG-15 (Russian: Микоян и Гуревич МиГ-15) (NATO reporting name "Fagot") was a jet fighter developed for the USSR. In March of 1946, Soviet leadership sought out a new swept-wing jet fighter from the leading aircraft design houses. The Mikoyan OKB's response was a design with the bureau designation I-310; a project that was influenced by plans for the Focke-Wulf Ta 183, which Soviet forces had captured when they overran Berlin in 1945. The I-310 first flew on the 30th December 1947. Previous Soviet designs like the MiG-9 had been hampered by the poor quality of available engines, but acquisition of the British Rolls-Royce Nene turbojet led to the development of an unauthorized local copy, the Klimov VK-1, which powered the I-310. MiG-15 undersideThe I-310 was a clean, swept-wing fighter with wings and tail swept at a 35° angle. Although it possessed a number of dangerous handling eccentricities (some of which were never really resolved), including pitch-up at transsonic speeds, it had exceptional performance, with a top speed of over 650 mph (1,040 km/h). The I-310's primary competitor was the similar Lavochkin La-168. After evaluations, the MiG design was chosen for production. Designated MiG-15, the first production example flew on 31 December 1948. It received the NATO reporting name "Fagot", entering Soviet air force service in 1949. An improved variant, the MiG-15bis ("bis" being Latin for "twice"), entered service in early 1950, with a number of changes intended to mitigate the aircraft's handling flaws.