Sukhoi Su-57

The Sukhoi Su-57 (Сухой Су-57) is the designation for a stealth, single-seat, twin-engine multirole fifth-generation jet fighter being developed for air superiority and attack operations. The aircraft is the product of the PAK FA (ПАК ФА, Перспективный авиационный комплекс фронтовой авиации), a fifth-generation fighter programme of the Russian Air Force. Sukhoi's internal name for the aircraft is T-50. The Su-57 will be the first aircraft in Russian military service to use stealth technology.

The fighter is designed to have supercruise, supermaneuverability, stealth, and advanced avionics to overcome the prior generation fighter aircraft as well as ground and naval defences. The Su-57 is intended to succeed the MiG-29 and Su-27 in the Russian Air Force.

The prototypes and initial production batch are to be delivered with a highly upgraded variant of the Lyulka AL-31 engine used by the Su-27 family as interim powerplant while an advanced clean-sheet design engine, the Saturn izdeliye 30, is currently under development. The aircraft is expected to have a service life of up to 35 years. Its first flight took place on 29 January 2010.

Origins
In 1979, the Soviet Union outlined a need for a next-generation aircraft intended to enter service in the 1990s. The project was designated the I-90 (Истребитель, Istrebitel, "Fighter") and required the fighter to have substantial ground attack capabilities and would eventually replace the MiG-29s and Su-27s in frontline tactical aviation service. The subsequent programme designed to meet these requirements, the MFI (МФИ, Многофункциональный фронтовой истребитель, Mnogofunksionalni Frontovoy Istrebitel, "Multifunctional Frontline Fighter"), resulted in Mikoyan's selection to develop the MiG 1.44. Though not a participant in the MFI, Sukhoi started its own programme in 1983 to develop technologies for a next-generation fighter aircraft, resulting in the S-37, later designated Su-47. Due to a lack of funds after the collapse of the Soviet Union, the MiG 1.44 programme was repeatedly delayed and the first flight of the prototype did not occur until 2000, nine years behind schedule. The MiG 1.44 was subsequently cancelled and a new programme for a next-generation fighter, PAK FA, was initiated. The programme requirements reflected the capabilities of Western fighter aircraft, such as the Eurofighter Typhoon and F-22 Raptor. In 2002, Sukhoi was selected over Mikoyan as the winner of the PAK FA competition and would lead the design of the new aircraft; Mikoyan continued to develop its proposal as the LMFS (ЛМФС, Легкий многофункциональный фронтальный самолёт, Liogkiy Mnogofunktsionalniy Frontovoi Samolyet, "Light Multifunctional Frontline Fighter") which was designed to be smaller and more affordable.

To reduce the PAK FA's developmental risk and spread out associated costs, as well as to bridge the gap between it and older previous generation fighters, some of its technology and features, such as propulsion and avionics, were implemented in the Sukhoi Su-35S fighter, an advanced variant of the Su-27. The Novosibirsk Aircraft Production Association (NAPO) is manufacturing the new multi-role fighter at Komsomol'sk-on-Amur along with Komsomolsk-on-Amur Aircraft Production Association (KnAAPO), and final assembly is to take place at Komsomol'sk-on-Amur. Following a competition held in 2003, the Tekhnokompleks Scientific and Production Center, Ramenskoye Instrument Building Design Bureau, the Tikhomirov Scientific Research Institute of Instrument Design (NIIP), the Ural Optical and Mechanical Plant (UOMZ) in Yekaterinburg, the Polet firm in Nizhny Novgorod and the Central Scientific Research Radio Engineering Institute in Moscow were selected for the development of the PAK-FA's avionics suite. NPO Saturn is the lead contractor for the interim engines; Saturn and MMPP Salyut will compete for the definitive second stage engines.

On 8 August 2007, Russian Air Force Commander-in-Chief (CinC) Alexander Zelin was quoted by Russian news agencies that the programme's development stage was complete and construction of the first aircraft for flight testing would begin, and that by 2009 there would be three fifth-generation aircraft ready. In 2009, the aircraft's design was officially approved.

Since the Su-57 will not likely be developed into an unmanned version, the aircraft is being currently used also as a testbed for technologies being developed for Russia's future sixth-generation combat system that in its basic version will be an unmanned aerial vehicle (UAV) possessing an ability to be optionally manned. The technologies being tested on board the Su-57 are supposed to be mainly control and navigation systems, including weapon systems.

Procurement


In 2007, Russia and India agreed to jointly develop the Fifth Generation Fighter Aircraft Programme (FGFA) for India. In September 2010, it was reported that India and Russia had agreed on a preliminary design contract where each country was to invest $6 billion; development of the FGFA fighter was expected to take 8–10 years. The agreement on the preliminary design was to be signed in December 2010. India planned on acquiring a modified version for its FGFA programme. It originally planned on buying 166 single-seat and 44 two-seat variants, but this was reduced to a requirement for 130-145 single-seat and 45-50 twin-seat aircraft by 2014. In early 2018, India pulled out of the FGFA project, which it believed did not meet its requirements for stealth, combat avionics, radars and sensors by that time. This news lead some observers to question the future of the whole Su-57 project.

The Russian Air Force was expected to procure more than 150 fighters for PAK FA with the first fighter to be delivered in 2016. In 2011, the Russia's Ministry of Defence planned on purchasing the first 10 evaluation aircraft after 2012 and then 60 production standard aircraft after 2016. In December 2014, the Russian Air Force planned to receive 55 fighters by 2020. Russian Deputy Minister of Defence Yury Borisov stated in 2015 that the Air Force would slow production, reduce its initial order to 12 fighters, and retain large fleets of fourth-generation fighters due to the nation's economy.

Russian Air Force Commander-in-Chief Viktor Bondarev stated that the fighter planned to enter serial production in 2017, after all trials would be completed. In 2017, Deputy Minister Yury Borisov stated that the Su-57 would most likely enter service in 2018, due to implementation of more advanced engines, and further testing. He also stated that it would be part of the new 2018-2027 state armament programme. Actual number of aircraft to be delivered is yet unknown.

On 30 June 2018, it was reported that an order for 12 aircraft was agreed,  with deliveries to the ranks of the Russian Armed Forces starting in 2019. The first aircraft will join fighter regiments at the Lipetsk Air Center. At the same time, the Deputy Prime Minister for Defence and Space Industry Yury Borisov stated that "Today, the Su-35 is one of the world's best fighters, so there is no reason for us to speed up work on mass production of the fifth-generation fighter." Borisov's statement caused confusion among observers. Some interpreted the fifth generation fighter he referenced as the FGFA, the exported variant of the Su-57, while others interpreted it to be directly alluding to the Su-57 itself. This also led to predictions and concerns about the project's future: some have interpreted it as reiteration that the Su-57 program would continue as previously planned, others interpreted it as the Su-57 program would not be mass produced, and some believe it to be an implicit announcement of the project's cancellation. The slowing of procurement could be because of the current slow growth of the Russian economy, while the future patches' procurement are for an unknown future; the Russian military could be waiting for the more powerful Saturn izdeliye 30 engine to be ready for serial production.

On 22 August 2018, during the International Military-Technical Forum «ARMY-2018», the Russian Ministry of Defence and the JSC Sukhoi signed the first contract for delivery of two serial Su-57s. The contract should be finalized between 2018 and 2020.

Initial flight testing


The prototype's maiden flight was repeatedly postponed from early 2007 after encountering unspecified technical problems. In August 2009, Alexander Zelin acknowledged that problems with the engine and in technical research remained unsolved. On 28 February 2009, Mikhail Pogosyan announced that the air-frame was almost finished and that the first prototype should be ready by August 2009. On 20 August 2009, Pogosyan said that the first flight would be by year's end. Konstantin Makiyenko, deputy head of the Moscow-based Centre for Analysis of Strategies and Technologies said that "even with delays", the aircraft would likely make its first flight by January or February, adding that it would take five to ten years for commercial production.

Flight testing was further delayed when Deputy Prime Minister Sergei Ivanov announced in December 2009 that the first trials would begin in 2010. The first taxi test was successfully completed on 24 December 2009. Flight testing began with T-50-1, the first prototype aircraft, on 29 January 2010. Piloted by Hero of the Russian Federation Sergey Bogdan, the aircraft's 47-minute maiden flight took place at KnAAPO's Dzemgi Airport in the Russian Far East.

The second aircraft was to initially start flight testing in late 2010; this was delayed until early 2011. On 3 March 2011, the second prototype, T-50-2, completed a 44-minute test flight. The first two prototypes lacked radar and weapon control systems. On 14 March 2011, the fighter achieved supersonic flight at a test range near Komsomolsk-on-Amur. The T-50 was displayed publicly for the first time at the 2011 MAKS Airshow. On 3 November 2011, the fighter reportedly performed its 100th flight. More than 20 test flights were made in the next nine months.

On 22 November 2011, the third prototype, T-50-3, took its first flight from KnAAPO's airfield in Komsomolsk-on-Amur, piloted by Sergey Bogdan. The aircraft spent over an hour in the air, and was subjected to basic stability and power-plant checks. It differs from the other prototypes in the way it lacks a pitot tube. At this time all 14 test aircraft were expected to fly by 2015. T-50-3 was the first prototype to fly with an AESA radar. Originally scheduled for the end of 2011, these flights occurred in August 2012, and showed performance comparable to existing radars.

The fourth prototype had its first flight on 12 December 2012 and joined the other three aircraft in testing near Moscow a month later. By the end of 2013, five prototypes were flown, with the fifth prototype having its first flight on 27 October 2013; with this flight the programme has amassed more than 450 flights. The first aircraft for State testing was delivered on 21 February 2014. However the VVS lacks facilities for testing some of the aircraft's performance parameters.

The fifth prototype, T-50-5 hull number 055, was severely damaged by an engine fire after landing in June 2014. The aircraft was returned to flying condition after cannibalizing components from the unfinished sixth prototype.

The sixth prototype first flew on 27 April 2016.

Overview


The Su-57 will be a fifth-generation multirole fighter aircraft and the first operational stealth aircraft for the Russian Air Force. Although most information is classified, sources within the Sukhoi company and Defence Ministry have openly stated that the aircraft is to be stealthy, supermaneuverable, have supercruise capability, incorporate substantial amounts of composite materials, and possess advanced avionics such as active phased-array radar and sensor fusion.

The Su-57 has a blended wing body fuselage and incorporates all-moving horizontal and vertical stabilizers; the vertical stabilizers toe inwards to serve as the aircraft's airbrake. The aircraft incorporates thrust vectoring and has adjustable leading–edge vortex controllers (LEVCONs) designed to control vortices generated by the leading edge root extensions, and can provide trim and improve high angle of attack behaviour, including a quick stall recovery if the thrust vectoring system fails. The advanced flight control system and thrust vectoring nozzles make the aircraft departure-resistant and highly maneuverable in both pitch and yaw, enabling the aircraft to perform very high angles of attack maneuvers such as the Pugachev's Cobra and the bell maneuver, along with doing flat rotations with little altitude loss. The aircraft's aerodynamics and engines enable it to achieve Mach 2 and is also capable of flying supersonic flight without afterburners, or supercruise; the high cruising speed and normal operating altitude is also expected to give it a significant kinematic advantage over prior generations of aircraft.

The aircraft will make extensive use of composites; on the first prototype, composites comprise 25% of the structural weight and almost 70% of the outer surface. Second stage prototype will increase the usage of composite material, as well as wider wingspan, stronger airframe and the possibility to install newer engines. According to Sukhoi design engineer, Alexander Shkoda, the airframe has a good balance between durability and weight, as shown during in-house testing to test the limit of its tensile strength characteristics; the test achieved a breaking point of 104 percent of maximum design load. An excellent result will be attained if aircraft's breaking point proved to be between 99 and 104% of the maximum load calculated by engineers during design work, while a result more than 104% means that the airframe is too heavy.

Weapons are housed in two tandem main weapons bays between the engine nacelles and smaller bulged, triangular-section bays near the wing root. Internal weapons carriage eliminates drag from external stores and enables higher performance compared to external carriage, as well as enhancing stealth. Advanced engines and aerodynamics enable the Su-57 to supercruise, sustained supersonic flight without using afterburners. Combined with a high fuel load, the fighter has a supersonic range of over 1500 km, more than twice that of the Su-27. Extendible refueling probe is available to further increase its range. In the Su-57's design, Sukhoi addressed what it considered to be the F-22's limitations, such as its inability to use thrust vectoring to induce roll and yaw moments and a lack of space for weapons bays between the engines, and complications for stall recovery if thrust vectoring fails.

Stealth
The Su-57 will be the first operational aircraft in Russian Air Force service to use stealth technology. Similar to other stealth fighters such as the F-22, the airframe incorporates planform edge alignment to reduce its radar cross-section (RCS); the leading and trailing edges of the wings and control surfaces and the serrated edges of skin panels are carefully angled to reduce the number of directions the radar waves can be reflected. Weapons are carried internally in weapons bays within the airframe and antennas are recessed from the surface of the skin to preserve the aircraft's stealthy shape. The infrared search-and-track sensor housing is turned backwards when not in use and its rear is treated with radar-absorbent material (RAM) to reduce its radar return. To mask the significant RCS contribution of the engine face, the partial serpentine inlet obscures most of the engine's fan and inlet guide-vanes (IGV). The production aircraft incorporates radar blockers similar in principle to those used on the F/A-18E/F in front of the engine fan to hide it from all angles. The aircraft uses RAM to absorb radar emissions and reduce their reflection back to the source and the canopy is treated with a coating to minimize the radar return of the cockpit and pilot.

The Su-57's design emphasizes frontal stealth, with RCS-reducing features most apparent in the forward hemisphere; the shaping of the aft fuselage is much less optimized for radar stealth compared to the F-22. The combined effect of airframe shape and RAM of the production aircraft is estimated to have reduced the aircraft's RCS to a value thirty times smaller than that of the Su-27. Sukhoi's patent of the Su-57's stealth features cites an average RCS of the aircraft of approximately 0.1–1 square meters. Like other stealth fighters, the Su-57's low observability measures are chiefly effective against high-frequency (between 3 and 30 GHz) radars, usually found on other aircraft. The effects of Rayleigh scattering and resonance mean that low-frequency radars, employed by weather radars and early-warning radars are more likely to detect the Su-57 due to its size. Such radars are also large, susceptible to clutter and are less precise.

Engines


Pre-production T-50 and initial production batches of the Su-57 will use interim engines, a pair of NPO Saturn izdeliye 117, or AL-41F1. Closely related to the Saturn 117S engine used by the Su-35S, the 117 engine is a highly improved and uprated variant of the AL-31 that powers the Su-27 family of aircraft. The 117 engine produces 93.1 kN (21,000 lbf) of dry thrust, 147.1 kN (33,067 lbf) of thrust in afterburner, and has a thrust to weight ratio of 10.5:1. The engines have full authority digital engine control (FADEC) and are integrated into the flight control system to facilitate maneuverability and handling.

The two 117 engines incorporate thrust vectoring (TVC) nozzles whose rotational axes are each canted at an angle, similar to the nozzle arrangement of the Su-35S. This configuration allows the aircraft to produce thrust vectoring moments about all three rotational axes, pitch, yaw and roll. Thrust vectoring nozzles themselves operate in only one plane; the canting allows the aircraft to produce both roll and yaw by vectoring each engine nozzle differently. The engine inlet incorporates variable intake ramps for increased supersonic efficiency and retractable mesh screens to prevent foreign object debris being ingested that would cause engine damage. The 117 engine is to also incorporate infrared and RCS reduction measures. In 2014, the Indian Air Force openly expressed concerns over the reliability and performance of the 117 engines; during the 2011 Moscow Air Show, a T-50 suffered a compressor stall that forced the aircraft to abort takeoff.

Production fighters from 2020 onward will be equipped with a more powerful engine known as the izdeliye 30, Compared to the 117, the new powerplant will have increased thrust, lower costs, better fuel efficiency, and fewer moving parts. Those features, along with subsequently improved reliability and lower maintenance costs will improve the aircraft performance and reliability. The izdeliye 30 is designed to be 30% lower specific weight than its 117 predecessor. The new engine is estimated to produce approximately 107 kN (24,054 lbf) of dry thrust and 176 kN (39,556 lbf) in afterburner. Full scale development began in 2011 and the engine's compressor began bench testing in December 2014. The first test engines are planned to be completed in 2016, and flight testing is projected to begin in 2017. According to Deputy Minister Borisov, flight testing with new izdeliye 30 engines will begin at Q4-2017. The new powerplant is designed to be a drop-in replacement for the 117 with minimal changes to the airframe.

On 5 December 2017, the first flight of the second Su-57 prototype (fuselage number 052) fitted with the izdeliye 30 engine took place at the Gromov Flight Research Institute. The 17–minute test flight was carried out by Sergei Bogdan, Sukhoi chief test pilot. The izdeliye 30 engine was installed on the port-side engine position while the izdeliye 117 engine remained on the starboard side. The izdeliye 30 features a new serrated nozzle that's slightly shorter but has larger diameter than the izdeliye 117 nozzle.

Armament
The T-50 prototype has two tandem main internal weapon bays each approximately 4.6 m long and 1.0 m wide and two small triangular-section weapon bays that protrude under the fuselage near the wing root. Internal carriage of weapons preserves the aircraft's stealth and significantly reduces aerodynamic drag, thus preserving kinematic performance compared to performance with external stores. The Su-57's high cruising speed is expected to substantially increase weapon effectiveness compared to its predecessors. Vympel is developing two ejection launchers for the main bays: the UVKU-50L for missiles weighing up to 300 kg and the UVKU-50U for ordnance weighing up to 700 kg.

For air-to-air combat, the Su-57 is expected to carry four beyond-visual-range missiles in its two main weapons bays and two short-range missiles in the wing root weapons bays. The primary medium-range missile is the active radar-homing K-77M (izdeliye 180), an upgraded R-77 variant with AESA seeker and conventional rear fins. The short-range missile is the infrared-homing ("heat seeking") K-74M2 (izdeliye 760), an upgraded R-74 variant with reduced cross-section for internal carriage. A clean-sheet design short-range missile designated K-MD (izdeliye 300) is being developed to eventually replace the K-74M2. For longer ranged applications, four large izdeliye 810 beyond-visual-range missiles can be carried, with two in each main weapons bay.

The main bays can also accommodate air-to-ground missiles such as the Kh-38M, as well as multiple 250 kg KAB-250 or 500 kg KAB-500 precision guided bombs. The aircraft is also expected to carry further developed and modified variants of Kh-35UE (AS-20 "Kayak") anti-ship missile and Kh-58UShK (AS-11 "Kilter") anti-radiation missile. For missions that do not require stealth, the Su-57 can carry stores on its six external hardpoints. Su-57 chief designer Alexander Davydenko has said that there is a possibility of the installation of BrahMos supersonic cruise missile on the Su-57 and its FGFA derivative; only one or two such missiles may be carried due to heavy weight of the BrahMos.

The aircraft has an internally mounted 9A1-4071K (GSh-30-1) 30 mm cannon near the right LEVCON root. The cannon is the lightest in 30mm class with 50kg weight, and could fire up to 1,800 rounds per minute. The cannon can fire blast-fragmentation, incendiary and armor-piercing tracer rounds and is effective against even lightly armored ground, sea and aerial target up to 800 m for aerial target and 1,800 m for ground target. The cannon is equipped with autonomous water cooling system, where water inside barrel jacket vaporized during operation.

Cockpit
The Su-57 has a glass cockpit with two 38 cm main multi-functional LCD displays similar to the arrangement of the Su-35S. Positioned around the cockpit are three smaller control panel displays. The cockpit has a wide-angle (30° by 22°) head-up display (HUD). Primary controls are the joystick and a pair of throttles. The aircraft uses a two-piece canopy, with the aft section sliding forward and locking into place. The canopy is treated with special coatings to increase the aircraft's stealth.

The Su-57 employs the NPP Zvezda K-36D-5 ejection seat and the SOZhE-50 life support system, which comprises the anti-g and oxygen generating system. The 30 kg oxygen generating system will provide the pilot with unlimited oxygen supply. The life support system will enable pilots to perform 9-g maneuvers for up to 30 seconds at a time, and the new VKK-17 partial pressure suit will allow safe ejection at altitudes of up to 23000 m. In November 2018, the system is said to be at the final stage of test -the stage of state flight tests- and the test pilots are already flying in this equipment.

Avionics
The main avionics systems are the Sh121 multifunctional integrated radio electronic system (MIRES) and the 101KS Atoll electro-optical system.

The Sh121 consists of the N036 Byelka radar system and L402 Himalayas electronic countermeasures system. Developed by Tikhomirov NIIP Institute, the N036 consists of the main nose-mounted N036-1-01 X band active electronically scanned array (AESA) radar, or active phased array radar (Активная фазированная антенная решётка, Aktivnaya Fazirovannaya Antennaya Reshotka, АФАР, AFAR) in Russian nomenclature, with 1,552 T/R modules and two side-looking N036B-1-01 X-band AESA radars with 358 T/R modules embedded in the cheeks of the forward fuselage for increased angular coverage. Moreover, the side-looking radar could enable Su-57 to employ extreme beaming tactic (fighter turns 90 degrees away/perpendicular to an enemy’s pulse doppler radar array, so enemy's radar would not detect/misintepret it as a nonmoving object) while still able to guide its own missile. The suite also has two N036L-1-01 L band transceivers on the wing's leading edge extensions that are not only used to handle the N036Sh Pokosnik (Reaper) friend-or-foe identification system but also for electronic warfare purposes. Computer processing of the X- and L-band signals by the N036UVS computer and processor enable the system's information to be significantly enhanced.

In 2012 ground tests of the N036 radar began on the third T-50 prototype aircraft. The L402 Himalayas electronic countermeasures (ECM) suite made by the KNIRTI institute uses both its own arrays and that of the N036 radar system. One of its arrays is mounted in the dorsal sting between the two engines. The system was mounted on the aircraft in 2014. The radar will reduce pilot load and make use of a new data link to share information between aircraft. The communication links will provide radio telephone communication and encrypted data exchange among various aircraft and also command centers (ground and sea-based and airborne). The S-111 system, as it is called, is capable of transmitting a large amount of information (include voice, video, and data from transponders and surveillance cameras) through centimeter wavelength radio channels inside a group of planes at speed up to 34.3 Mbit/s. The new generation antenna-feeder system is able to combine antennas for various kinds of transceiver equipment (for communications, navigation, identification, etc.) in the fuselage shell, which is protected by a radar-transparent coating. It will not only minimize the number of antenna devices, but also reduces wind resistance and the radar signature of the aircraft thus enhancing stealth characteristic of the aircraft. Developed by Federal Research and Development Center NPP Polet, the system will be based on modular concept and could be installed not only on Su-57, but also on various aircraft, helicopter, and drones. The Government certification tests of the system will be over by the end of 2017. "Its effective range of operation is up to 1500 km," as spokesman for the Roselektronika holding company told TASS. "The system's reliability is guaranteed by the multiple redundancy of the main functions and cutting edge technical solutions, as well as a wide range of radio channels."

The UOMZ 101KS Atoll electro-optical system consisted of:


 * The 101KS-V infra-red search and track turret mounted on the starboard side in front of the cockpit. This sensor can detect, identify, and track multiple airborne targets simultaneously. It can also be used to provide targeting information to a fighter's missiles in-flight, even while that jet is not facing directly to its adversaries. Above all else it allows the Su-57 to operate and persecute targets while staying electromagnetically silent (giving off no radio emissions).
 * The 101KS-O Directional Infrared Counter Measures system has sensors housed in turrets mounted on the dorsal spine and forward fuselage under the cockpit and uses modulated laser-based countermeasures to confuse or destroy heat-seeking missiles' tracking mechanism. Judging from its position, the system allegedly intented not only as a self-protection against MANPADS but also air-to-air missile. In this regard, Su-57 could be something of a pioneer, while similar DIRCM capabilities haven't been ported over to the latest generations of high-flying western fighter aircraft.
 * The 101KS-U ultraviolet missile approach warning sensors (MAWS) against infra-red homing missiles. MAWS using ultraviolet technology can operate under all weather conditions and will not be affected by solar clutter. It provides good directional information of the incoming missile for good decoy dispensing decision making, maneuvering and to cue the DIRCM system into action. Two of them, the 101KS-U / 02 have the shape of a house with two windows, one dedicated to the sector front & the rear sector; one is located under the front fuselage, and the other one on the upper surface of the 'tail' between the two nozzles engines. The other two, U-101KS / 01 are mounted on either side of the fuselage, just aft of the cockpit.
 * The 101KS-P, a high-resolution thermal imager, provides low-altitude piloting and landing in night conditions. It is installed in front of the compartments of short-range missiles and is not used for targeting purposes but for efficient low altitude flight and night landing operations.
 * 101KS-N navigation and targeting pod. It will have similar function to the AN/AAQ28 Litening and AN/AAQ33 Sniper advanced targeting pods of the US military. Despite earlier report stating that it would be integrated into the airframe to minimize the PAK-FA’s RCS, prototype 055 was seen carrying a 101KS-N targeting pod mounted on the port-side engine nacelle during a flyover to mark the 65th anniversary of the Lukhovitsky aviation plant on Aug. 17 2018. Not only it could give Su-57 precision ground attack capabilities in all weather, day or night, it also allow the pilot to take images and videograph the location to be shared among allied forces.

In April 2017, UAC announced that a new next-generation integrated avionics suite has started flight-testing. According to Dmitry Gribov, a chief designer of the new complex, the new avionics suite—called the ИМА БК, the Russian acronym for Интегрированная модульная авионика боевого комплекса (integrated modular avionics combat systems)—will replace a system designed in 2004 called Багет (Baguette) used on previous Su-35. The still-in-development system has more than 4 million lines of code. The IMA BK makes use of indigenous Russian multi-core microprocessors and a new indigenous real-time operating system. The new avionic suite also makes use of fiber-optic channels with a throughput of more than 8 Gbit/s, which is up from 100 Mbit/sec for traditional copper wires. The new IMA BK integrated avionics suite is designed to automatically detect, identify, and track the most dangerous targets and offer the pilot the best solution to engage an enemy. "The new system takes control of almost all of the key sensors of the aircraft—radar, navigation and communication that in previous aircraft were controlled by separate computers," the company says. According to the designers, they use unique approach for the design of the avionics for the Su-57 compared to F-22 or F-35, where the complex is designed to process just the ‘upper part’ of data package instead of the entire volume of primary data. This allows it to work faster, more reliable and efficient. Designers also say the network structure of Su-57’s avionics complex increases reliability of all of its units, which means if one of the computers fails, the systems automatically switch to another unit. Additionally, the use of a centralized processor reduces the weight of the entire complex by almost two times, compared to its previous analogue-centered Russian fighter jet avionics.

During MAKS 2017, Foundation for Advanced Research Projects (FPI) presented an aircraft structural monitoring system based on the principles of operation of living organisms' nervous system designed to improve flight safety. The system will allow real-time assessment of the aircraft's condition and predict the remaining 'life' of the composite parts of the aircraft by combining optical fibers with sensitivity to mechanical influences with aircraft's network system. The information about aircraft's condition will be transmitted via laser beam through the optical fiber woven into the structure. It will decrease aircraft's maintenance costs by eliminating the need for expensive scheduled examinations since the aircraft's actual condition will be monitored accurately, and parts will be repaired on time, thus improving flight safety. To show how the system works, FPI presented a mock-up of the advanced PAK FA fighter, made of composite materials which is designed in such a way that if it is deformed (e.g. by bending the wing), the external impact is displayed on a screen.

Testing and trials
The 929th State Flight Test Centre (GLITS) received its first T-50 prototype for further testing and state trials in March 2014, and Russian Air Force Commander-in-Chief Lieutenant General Viktor Bondarev said that deliveries of initial production T-50 fighter were expected to begin in 2016. External weapon trials started in May 2014.

On 8 February 2018, Deputy Minister Borisov said that the first stage of state trials has been concluded and that the combat trials are on schedule. During the interview, he also reported that the contract for an initial batch of 12 aircraft is to be signed in 2018.

Syrian combat evaluation
On 21 February 2018, two Su-57s were spotted landing at the Russian Khmeimim air base in Syria. The aircraft were 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 were reported to have arrived in Syria. The deployment was criticised by some experts as overly risky, especially after reports of drones attack at Khmeimim air base. Military correspondent of Komsomolskaya Pravda Viktor Baranets was cited as saying that according to his information the Su-57s have "excellently" carried out their mission in Eastern Ghouta. On 1 March 2018, the Russian Defence Minister Sergey Shoygu confirmed that the two Su-57s indeed spent two days in Syria and successfully completed a trials program, including combat trials during which parameters of weapons work were monitored.

On 25 May 2018, the Russian Defence Ministry revealed that during the February 2018 deployment to Syria, a Su-57 fired a cruise missile in combat. Based off the video of the missile launch released by the Defence Ministry, the weapon was likely a Kh-59MK2.

On 18 November 2018, the Russian Defence Ministry posted a video of the fighters’ flights on Twitter, and announced that Su-57 performed 10 flights during its trip to Syria. The Defense Ministry also said that the deployment tested the Su-57’s flight and technical characteristics, its intellectual information control technology, onboard systems and armament amid high temperatures, complex relief and other factors in Syria. However, the video didn't specify when the test flight took place.

FGFA
The completed joint Indian/Russian versions of the single-seat or two-seat FGFA will differ from the current T-50 flying prototypes in 43 ways with improvements to stealth, supercruise, sensors, networking, and combat avionics.

In March 2010, Sukhoi director Mikhail Pogosyan projected a market for 1,000 fighter aircraft over the next four decades, which will be produced in a joint venture with India, 200 each for Russia and India and 600 for other countries. He has also said that the Indian contribution would be in the form of joint work under the current agreement rather than as a joint venture. In June 2010, the Indian Air Force planned to receive 50 of the single-seat "Russian version" before receiving the two-seat FGFA. Then in an October 2012 interview the Chief of Air Staff of India, NAK Browne, said that the IAF will purchase 144 of the single-seat FGFA. To reduce development costs and timelines, the IAF plans to begin induction of the FGFA in 2020.

In April 2018, it was reported that India is withdrawing from the program. India has become increasingly disappointed with the project's progress after years of negotiations, delays, and struggles with Russia. India is also not satisfied with the capabilities of Su-57, the basis of the FGFA with one of the main issues being the Su-57's insufficient stealth design.

Other versions
Alexei Fedorov has said that any decision on applying fifth-generation technologies to produce a smaller fighter (comparable to the F-35) must wait until after the heavy fighter, based on the T-50, is completed.

A proposal naval version of the Su-57 for the Project 23000E or Shtorm supercarrier. Models of the aircraft carrier project are showing Su-57 on board, with folding wings and stabilators. The Su-57 should be able to use the takeoff ramp as well as the Electromagnetic Aircraft Launch System.

Exports
Sukhoi states that the main export advantage of the PAK FA is its lower cost than current US fifth generation jet fighters. Russia was reported to be offering the PAK FA for South Korea's next generation jet fighter. South Korea's defence procurement agency confirmed that the Sukhoi PAK FA was a candidate for the Republic of Korea Air Force's next-generation fighter (F-X Phase 3) aircraft; however, Sukhoi did not submit a bid by the January 2012 deadline.

Russia's Centre for Analysis of World Arms Trade predicts that the PAK FA will be available for export in 2025; though this may include the Sukhoi/HAL FGFA for India, the primary export version. Ruslan Pukhov, director of the Centre for Analysis of Strategies and Technologies, has projected that Vietnam will be the second export customer for the fighter. In 2012, Russian Defence Minister Anatoly Serdyukov said that Russia and India would jointly build the export version of the T-50 starting in 2020. Mikhail Pogosyan, the head of United Aircraft Corporation, said in 2013 that the Russian PAK FA and the Sukhoi/HAL FGFA will use "identical onboard systems and avionics".

In 2013, Russia offered Brazil participation and joint production in a next-generation fighter based on the T-50.

Operators

 * Russian Aerospace Forces – confirmed in June 2018 it will buy 12 aircraft. 2 aircraft on order.
 * Russian Aerospace Forces – confirmed in June 2018 it will buy 12 aircraft. 2 aircraft on order.

Accidents
On 10 June 2014, the fifth flying prototype, aircraft T-50-5, was severely damaged by an engine fire after landing. The pilot managed to escape unharmed. Sukhoi stated that the aircraft will be repaired, and that the fire "will not affect the timing of the T-50 test program".