Sukhoi Su-57

• 1. Origins And Program Initiation

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  In 1979, the Soviet Union outlined a need for next-generation fighter aircraft intended to enter service in the 1990s. The programme became known as I-90 and required the fighter to be multifunctional with substantial ground attack capabilities. Two subsequent projects were designed to meet these requirements: the MFI and smaller LFI, with conceptual work beginning in 1983. Mikoyan was selected for the MFI and began developing its MiG 1.44/1.42. Though not a participant in the MFI, Sukhoi started its own programme in 1983 to develop technologies for a next-generation fighter. This eventually resulted in the forward-swept wing S-32 experimental aircraft, later redesignated S-37 and then Su-47.

  Due to a lack of funds after the dissolution of the Soviet Union, the MFI was repeatedly delayed. The first flight of the MiG 1.44/1.42 prototype did not occur until 2000, nine years behind schedule. Owing to high costs, the MFI and LFI were eventually cancelled while the Russian Ministry of Defence began work on a new next-generation fighter programme. In 1999, the ministry initiated the PAK FA or I-21 programme. The competition was announced in April 2001. Because of Russia's financial difficulties, the programme aimed to rein in costs by producing a single multirole fifth-generation fighter that would replace both the Su-27 and the MiG-29.

  Sukhoi's approach to the PAK FA competition differed fundamentally from Mikoyan's. Whereas Mikoyan proposed for three design bureaus to cooperate as a consortium with the winning team leading the design effort, Sukhoi's proposal had itself as the lead designer from the beginning. It included a joint work agreement covering the entire development and production cycle. In April 2002, the Ministry of Defence selected Sukhoi over Mikoyan as the winner of the PAK FA competition. Flight tests were projected to begin in 2007 according to Russian Air Force Commander-in-Chief Vladimir Mikhaylov.

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• 2. Prototyping And Structural Redesign

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  The T-50's maiden flight was repeatedly postponed from early 2007 after encountering unspecified technical problems. On the 28th of February 2009, Sukhoi general director Mikhail Pogosyan announced that the airframe was almost finished. He stated that the first prototype should be ready by August 2009. The first taxi test was successfully completed on the 24th of December 2009. The maiden flight of the first prototype aircraft, T-50-1, occurred on the 29th of January 2010. Piloted by Sukhoi test pilot Sergey Bogdan, the aircraft's 47-minute maiden flight took place at KnAAPO's Dzemgi Airport in the Russian Far East.

  A total of ten flying and three non-flying T-50 prototypes would be built for preliminary flight tests. Initially, the program was planned to have up to six prototypes before the start of serial production. However, testing revealed that the initial prototypes did not have adequate fatigue life. Early structural cracks formed in the airframe during public displays at MAKS-2011 despite flying with a restrictive 5-g limit. This necessitated grounding and structural reinforcing for over a year as well as a second stage structural redesign.

  The aircraft subsequently underwent a structural redesign with changes including increased composite material usage and reinforced airframe to meet full life cycle requirements. The sixth flyable prototype was the first of the redesigned second stage aircraft. The five initial prototypes were consequently considered first stage vehicles requiring additional structural reinforcements. In June 2014, the fifth prototype was severely damaged by an in-flight fire and written off. An incomplete first stage airframe was finished using parts salvaged from the fifth prototype. It was renamed T-50-5R carrying the same 055 bort number.

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• 3. Stealth Technology And Design Philosophy

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  The Su-57 employs a variety of methods to reduce its radar signature similar to other stealth fighters such as the F-22. The aircraft aligns planform edges to reduce its radar cross-section. Leading and trailing edges of wings and control surfaces are carefully angled to reduce the number of directions radar waves can be reflected. Weapons are carried internally in weapons bays within the airframe. Antennas are recessed from the surface of the skin to preserve the aircraft's stealthy shape. Radar absorbent material coatings absorb radar emissions and reduce reflection back to the source.

  To mask significant RCS contribution of the engine face, walls of inlet ducts are coated with RAM. Partial serpentine ducts obscure most of engines' compressor face and inlet guide vanes. Remaining exposed engine face is masked by slanted blocker grid placed in front of IGV at distance of 0.7 to 1.2 times diameter of duct. Aircraft canopy is coated with 70 to 90 nm thick metal oxide layers with enhanced radar wave absorbing. This reduces radar return of cockpit by 30 percent and protects pilot from impact of ultraviolet and thermal radiation.

  Combined effect of airframe shape and RAM of production aircraft is estimated to have reduced aircraft's RCS to value thirty times smaller than that of Su-27. Sukhoi patent for T-50 stealth features cites intention to reduce average RCS to approximately 0.1 to 1 m2 compared to Su-27's RCS of approximately 10 to 15 m2. Design emphasizes frontal stealth with RCS-reducing features most apparent in forward hemisphere. Shaping of aft fuselage is less optimized for radar stealth compared to American stealth designs such as F-22 and F-35 likely due to cost reduction.

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• 4. Engine Development And Performance

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  The Su-57 is powered by pair of NPO Lyulka-Saturn izdeliye 117 or AL-41F1 augmented turbofans. Engine produces 9 tonnes dry thrust and 14.5 tonnes thrust in afterburner. It also generates 15 tonnes thrust in special emergency power. Engines have full authority digital engine control integrated into flight control system to facilitate maneuverability and handling. The AL-41F1 is closely related to Lyulka-Saturn izdeliye 117S used by Su-35S.

  Aircraft employs thrust vector control where vectoring nozzles' rotational axes are each canted at angle similar to nozzle arrangement first employed on Su-30MKI. Nozzles themselves vector in only one plane. Canting allows roll and yaw moments by vectoring each nozzle differentially. This enables aircraft to produce thrust vectoring moments about all three aircraft axes: pitch, yaw and roll. In 2014 Indian Air Force openly expressed concerns over reliability and performance of AL-41F1 especially due to lack of supercruise ability.

  Planned Su-57M will be equipped with new engine from NPO Saturn in mid-2020s under development designation izdeliye 30. Powerplant designed with estimated thrust of 11 tonnes dry and 17 tonnes in afterburner. First flight of izdeliye 30 engine occurred on the 5th of December 2017 with second prototype T-50-2 bort no. 052. In 2023 it was reported that UEC Saturn is developing alternative non-axisymmetric flat nozzle for Su-57. Flight testing began in late 2024.

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• 5. Operational History In Syria And Ukraine

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  On the 21st of February 2018 two Su-57s performed their first international flight as they were spotted landing at Russian Khmeimim air base in Syria. Aircraft deployed along with four Sukhoi Su-35 fighters, four Sukhoi Su-25s, and one Beriev A-50 AEW&C aircraft. Three days later two more Su-57s reported to have arrived in Syria. On the 1st of March 2018 Russian Defence Minister Sergey Shoygu stated that two Su-57s had spent two days in Syria and successfully completed trials program including combat trials during which parameters of weapons work monitored.

  In May 2022 Russian sources claimed Su-57 fighters used two or three weeks after start of 2022 Russian invasion of Ukraine striking targets with missiles outside zone activity of Ukrainian air defenses. In June 2022 RIA Novosti reported four Su-57s working in network used in SEAD role over Ukraine to identify and destroy Ukrainian air defense systems. On the 19th of October 2022 Russian army general Sergey Surovikin then commander all Russian Armed Forces in Ukraine claimed Su-57 used both in air-to-air and air-to-ground role during war in Ukraine.

  On the 9th of June 2024 Ukrainian Main Directorate of Intelligence claimed to have damaged or destroyed two Russian Su-57 fighter jets using drones during strike on Akhtubinsk air base in Astrakhan Oblast. Several Telegram channels affiliated with Russian military confirmed attack and at least one Su-57 damaged by shrapnel. Maxar Technologies satellite imagery showed crater next to Su-57 at Akhtubinsk.

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• 6. Export Efforts And International Partnerships

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  Sukhoi states main export advantage of PAK FA is lower cost than current US fifth generation jet fighters. Russia reported offering PAK FA for South Korea's next generation jet fighter. South Korea Defense Acquisition Program Administration stated Sukhoi PAK FA candidate for Republic of Korea Air Force F-X Phase 3 aircraft. However, Sukhoi did not submit bid by January 2012 deadline. In May 2019 as Turkish participation in F-35 program doubted due to Turkey procurement S-400 missile system CEO Rostec Sergey Chemezov said Russia ready cooperate with Turkey on export and local production Su-57.

  On the 27th of December 2019 Algeria signed contract for 14 aircraft as part large military deal that also includes purchase Su-34 and Su-35 fighters. This decision reportedly taken summer 2019 when Algerian delegation personally inspected Su-57 at MAKS-2019 air show. Algeria confirmed acquisition set receive first Su-57E in 2025. Reports suggest they could arrive to Algeria by end 2026. On the 18th of November 2025 CEO Russia United Aircraft Corporation claimed first two Su-57s delivered foreign customer entered combat duty without specifying customer likely Algeria.

  In early stages PAK FA programme India planned be one largest foreign customers procuring FGFA derivative originally planned buy 166 single-seat and 48 two-seat fighters later changed it to 214 single-seat fighters reduced purchase to 144 fighters by 2012. In April 2018 India pulled out FGFA project believed did not meet requirements stealth combat avionics radars sensors Indian Air Force Air Chief Marshal Birender Singh Dhanoa stated Su-57 currently not being considered service but aircraft can evaluated once enters service Russian Aerospace Forces.

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