The Tumansky R-79V-300. is an afterburning turbofan developed by NPO Soyuz in the Soviet Union, now AMNTK Soyuz in Russia. The R-79 is a vectored-thrust afterburning turbofan used as powerplant for the supersonic Yak-141 vertical takeoff/landing (VTOL) fighter aircraft designed by Yakovlev to replace the Yak-38
The development of the R-79 began in the late 1970 under the direction of V.K. Kobchenko with development project designation Izdeliye 79 ('Product 79'). The design and development of the R-79V-300 was driven by the requirement of designing a power plant for a supersonic V/STOL aircraft working alongside two lift engines (RD-41). Unlike its predecessor, the thrust-vectored non-afterburning turbofan Tumansky R-27 used in the Yak-38, the R-79 single exhaust design combined with a three-joints ring swivel nozzle made possible an afterburner turbofan capable of operate in any nozzle position.
The R-79V-300 used in the Yak-141 is a two-shaft axial-flow afterburning turbofan with counter-rotating spools to reduce weight and gyroscopic forces on the engine. The engine has a three-stage low-pressure compressor (fan) and an eleven-stage high-pressure compressor, with bleed air from after the 6th stage for roll control. Both compressors are driven by a pair of counter-rotating 2-stage turbines. However the bleed air for roll control, up to 10 kg/s taken from the core will reduce the thrust. Paired with two RD-41 (4.1 kN, 4,260 kgf) they totals a thrust in hovering mode of at ISA conditions.
Ground testing, production and test flights extended from 1983 to 1991 when the Yak-141 was cancelled.
During the 1990s Soyuz developed an alternative rectangular nozzle for vector control in the pitch axis, replaced the analogue electronic engine controller with a FADEC and increased thrust. Nevertheless, this improved version and a non-augmented R-79V-300 variant designated VK-21 have no reported application. In the early 2000s AMNTK Soyuz developed a 30 MW gas turbine using the core and turbines of the R-79V-300 replacing the low pressure compressor and adding a 5-stage power turbine developed by JSC Kuznetsov.
with reheat