Saturn AL-51F-1

In the 1990s, the collapse of the Soviet Union resulted in the disruption of funding and lengthy delays of the Mikoyan Project 1.44 for the MFI fifth-generation fighter program along with its engines, the variable cycle 18–tonne (177 kN, 40,000 lbf) class NPO Lyulka-Saturn AL-41F, internally designated izdeliye 20.[1] In 1999, as the MFI and LFI programs were gradually being abandoned, the Russian Defence Ministry initiated the more affordable PAK FA next-generation fighter program to replace the MiG-29 and Su-27. The competition was announced in April 2001, and Sukhoi submitted its T-50 proposal with a pair of 14.5-tonne (142 kN, 32,000 lbf) class Lyulka-Saturn AL-41F1, internally designated izdeliye 117, for the PAK FA.[2][3] Sukhoi was selected as the winner of the competition in April 2002 and in April 2004, it signed a contract with Lyulka-Saturn, now NPO Saturn, to develop the AL-41F1.[4] Despite its name, the engine is actually a highly uprated and improved variant of the earlier-generation Lyulka AL-31, originally designed for the Su-27. While the AL-41F1 used the same basic architecture, it had 80% new parts and applied technology from Lyulka-Saturn's original AL-41F, which was too large for the T-50.[5][6]

Although Sukhoi specified the AL-41F1 in the contract, the bureau anticipates that its T-50 design, eventually designated the Su-57, would be the basis for a family of stealth combat aircraft, with future variants employing more powerful engines. Following a competition between NPO Saturn and MMPP Salyut, the former was selected to develop the new engine, a clean-sheet design designated the izdeliye 30, that would equip the improved Su-57M variant in the mid-2020s.[7][8][9] Compared to the AL-41F1, the new powerplant will have increased thrust, lower costs, better fuel efficiency, and fewer moving parts; the engine also has glass-fibre plastic inlet guide-vanes (IGV) and a new nozzle with serrated flaps to reduce the aircraft's radar signature. Those features, along with subsequently improved reliability and lower maintenance costs will improve the aircraft performance and reliability.[10][11] The izdeliye 30 is designed to have fewer stages than the AL-41F1 and be up to 18% more effective.[12] Full scale development began in 2011 and the engine's compressor began bench testing in December 2014.[12] The first test engines were completed in 2016.[13] The new powerplant is designed to be a drop-in replacement for the AL-41F1 with minimal changes to the airframe.[14]

First flight of the engine on an Su-57 prototype occurred on 5 December 2017 with the second prototype (T-50-2, bort no. 052).[15][16] However, the engine’s development has seen a sluggish flight test pace; originally planned to enter service in the early 2020s, the izdeliye 30’s planned introduction has been delayed to the mid-2020s.[17][18] In 2023, the engine was given the designation AL-51F-1.[19]

The AL-51F-1 is a two-shaft low-bypass afterburning turbofan engine. The architecture is a three-stage fan driven by a single-stage low pressure turbine and five-stage high pressure compressor driven by single-stage high pressure turbine.[10] Unlike its AL-41F1 predecessor, the engine has glass-fiber plastic IGVs and convergent-divergent nozzles that use serrated flaps to reduce its radar signature as well as 19% higher thrust-to-weight ratio, 6.4% better specific thrust, and 9% lower specific fuel consumption; estimated thrust is 107.9 kN (24,300 lbf) dry and 166.8 kN (37,500 lbf) in afterburner.[20] The AL-51F-1 has full authority digital engine control (FADEC) to ensure its reliability in various operating conditions.[21]

• Sukhoi Su-57M (planned)
• Sukhoi Su-75 Checkmate (planned, derivative)

Data from Key Aero,[21] Aviation Week[10]

• Saturn AL-41

Comparable engines

• Pratt & Whitney F119
• Xian WS-15

Related lists

• List of aircraft engines