The Tumansky R-21 was developed at Tushino motor plant (part of OKB-300), headed by Nikolai Georgievich Metskhvarishvili, as a twin-spool axial-flow afterburning turbojet.
It was based on the Tumansky R-11 with the goal of increasing thrust and airflow, using a new six-stage compressor with a larger diameter and different rotor blades than its predecessor as well as a new afterburner chamber and variable exhaust nozzle.
The increased pressure ratio and turbine inlet temperature required components to be fabricated from advanced alloys.
On September 11, 1962 an R-21, fitted to a Ye-8, exploded in mid-air after compressor failure; test pilot Georgy Mosolov survived the ejection at Mach 1.78, but he never fully recovered.
[2] Shortly afterward the Ye-8 program was cancelled along with R-21 development in favour of heavier fighter planes such as the Mikoyan-Gurevich MiG-23, which required more powerful engines.