World’s Fastest Super Cruiser: Russian Su-57 Fighter’s New Engine to Facilitate Mach 2+ Non-Afterburner Flight – Reports

The Russian Air Force is scheduled to begin receiving an enhanced new variant of the Su-57 fifth generation fighter from 2025, the Su-57M, which was reported in October 2022 to have begun flight testing and will integrate a new engine designated AL-51F. Although Russia’s fighter aviation industry has consistently missed announced projections for bringing new systems into service, the Su-57M is almost certain to begin deliveries before 2027. While much regarding the capabilities the new engine will bring to the Su-57 remains unknown, recent reports from Russian sources indicate that the AL-51F will allow the fighter to cruise without using afterburners not only at supersonic speeds – a capability known as supercruise – but to do so at speeds of Mach 2 or more. The only tactical combat jet currently capable of Mach 2+ cruise is the MiG-31 Foxhound interceptor, although it requires afterburners to do so, with this capability allowing the Su-57 to respond to threats and conduct patrols far more quickly without taking a toll on its range. Use of afterburners burns fuel far more quickly and thus makes flying supersonically unviable for extended periods for the large majority of fighter aircraft while reducing their ranges significantly. Currently the only fifth generation fighter in production capable of supercruise is the Chinese J-20, although this can only be achieved at low supersonic speeds a little over Mach 1. The American F-35 cannot fly supersonically without using its afterburners. 

Known in its development stages as the Saturn 30, after the name of the firm primarily responsible for the program UEC Saturn, the AL-51F engine represents Russia’s second attempt at a fifth generation design after the highly promising AL-41F, which although developed to readiness for serial production was considered too costly to produce for the MiG 1.42 fighter it was intended to power. With the Su-57 costing approximately half as much as the MiG 1.42 was expected to, its AL-51F engine is also reported to have lower operational and production costs. The new engine is well optimised for stealth, and benefits from convergent-divergent nozzles with serrated flaps to reduce its radar cross section. Its thrust is estimated to be approximately 8 percent higher than that of its closest American rival the F-22’s F119, although its primary advantage is expected to be its much lower maintenance requirements and three dimensional thrust vectoring capability for much improved low speed manoeuvrability. Although the Su-57’s range is already over double those of its American rivals the F-35 and F-22, the AL-51F will further improve the range of the fighter by close to 10 percent.