طيار اختبار
The two prototypes flew in 1962. On September 11, 1962, the Tumansky R-21F-300 engine, also under development, exploded in midair at a speed of Mach 2.15. Test pilot Georgy Konstantinovich Mosolov, then one of the leading Soviet test pilots, was severely injured by debris from the compressor and had to eject at Mach 1.78.