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.[3]
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 10kg/s taken from the core will reduce the thrust. Paired with two RD-41 (4.1kN, 4,260 kgf) they totals a thrust in hovering mode of 20,500kgf (45,194.8lbf) at ISA conditions.[4]
Ground testing, production and test flights extended from 1983 to 1991 when the Yak-141 was cancelled.[5]
Further developments
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.[6] Nevertheless, this improved version and a non-augmented R-79V-300 variant designated VK-21[7] 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.[8]
Improved version with higher maximum thrust, FADEC and new rectangular nozzle that enable a control of ±20° in the pitch axis. 176–200kN (40,000–45,000lbf) thrust.
Aero-derivative gas turbine with a capacity of 30MW and 33 MW peak power with a thermal efficiency of 36% developed since 2002–2003 and presented at 2005 MAKS but with little information after that. Airflow: 99.3 kg/s, Overall pressure ratio: 22.1:1.
Piotr Butowski, John Fricker (1995). Yakovlev's V/STOL Fighters... p.35.
Further reading
Piotr Butowski, John Fricker (1995). Yakovlev's V/STOL Fighters Yak 36, Yak 38, Yak 41 and Yak 141: The Full Story of Russia's Rival to the Harrier. Aerofax Inc. / Midland Counties Publications Ltd. ISBN978-1-85780-041-8.
Зрелов В.А, Маслов В.Г. (1999). Основные данные отечественных авиационных ГТД и их[Zrelov V.A., Maslov V.G. Basic data of domestic aviation gas turbine engines and their application in educational design.] (in Russian). Russia: Samara State Aerospace University. ISBN5-7883-0056-8.
