In 1954, the MiG OKB began to investigate the potential of a mixed-power, short-range point defence interceptor as a variation of the Ye-2, the result being designated Ye-50. Designed around a Tumansky AM-9Ye (RD-9Ye) turbojet with an afterburning thrust of 3800kg and a Dushkin S-155 bi-fuel rocket motor of 1300kg, the first of three prototypes, the Ye-50/1, flew on 9 January 1956. It began trials with the rocket motor on 8 June 1956. A year later, on 17 June 1957, the second prototype, the Ye-50/2, attained a speed of Mach=2.33 and an altitude of 25600m. The Ye-50/2 introduced some modifications to the rear fuselage and vertical tail, and the Ye-50/3 featured a lengthened fuselage nose and increased internal fuel. This last prototype was lost during flight test when its vertical tail detached. The Gor'kiy factory was ordered to build a batch of 20 aircraft, which, powered by the AM-11 engine and S-155 rocket, were to be designated Ye-50A. These were intended for operational evaluation, but none of them was built owing to a lack of rocket motors, the Dushkin OKB having meanwhile closed down.