Sukhoi PAK FA
|A T-50 flies at the MAKS 2011 air show|
|Role||Stealth multirole/Air superiority fighter|
|First flight||29 January 2010|
|Primary users||Russian Air Force
|Number built||5 prototypes|
|Program cost||US$8–10 billion (est.)|
T-50: US$50+ million
The PAK FA (Russian: ПАК ФА, Russian: Перспективный авиационный комплекс фронтовой авиации, Perspektivny Aviatsionny Kompleks Frontovoy Aviatsii, literally "Prospective Airborne Complex of Frontline Aviation") is a fifth-generation fighter programme of the Russian Air Force. The T-50 is the name of the prototype aircraft (though it is unlikely it will be the name for the production aircraft) designed by Sukhoi for the PAK FA programme. The aircraft is a stealthy, single-seat, twin-engine jet fighter, and will be the first operational aircraft in Russian service to use stealth technology. It is a multirole fighter designed for air superiority and attack roles. The fighter is planned to have supercruise, stealth, supermaneuverability, and advanced avionics to overcome the prior generation of fighter aircraft as well as ground and maritime defences.
The PAK FA is intended to be the successor to the MiG-29 and Su-27 in the Russian Air Force and serve as the basis for the Fifth Generation Fighter Aircraft (FGFA) being co-developed by Sukhoi and Hindustan Aeronautics Limited (HAL) for the Indian Air Force. The T-50 prototype first flew on 29 January 2010 and the first production aircraft is slated for delivery to the Russian Air Force starting in late 2016 or early 2017. The prototypes and initial production batch will be delivered with a highly upgraded variant of the AL-31F used by the Su-27 family as interim engines while a new clean-sheet design powerplant is currently under development. The aircraft is expected to have a service life of up to 35 years.
- 1 Development
- 2 Design
- 3 Operational history
- 4 Variants
- 5 Accidents
- 6 Specifications (T-50)
- 7 See also
- 8 References
- 9 External links
In the late 1980s, 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 (Russian: 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 program designed to meet these requirements, the MFI (Russian: МФИ, Russian: 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 program in the early 1990s to develop technologies for a next-generation fighter aircraft, resulting in the S-37, later designated as the Su-47. Due to a lack of funds after the collapse of the Soviet Union, the MiG 1.44 program 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 canceled and a new program for a next-generation fighter, PAK FA, was initiated. The program requirements reflected the capabilities of Western fighter aircraft, such as the Eurofighter Typhoon and F-22 Raptor. Following a competition between Sukhoi, Mikoyan, and Yakovlev, in 2002, Sukhoi was selected as the winner of the PAK FA competition and selected to lead the design of the new aircraft.
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 multirole 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 program'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.
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 invests $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.
The Russian Air Force is expected to procure more than 150 PAK FA aircraft, the first of which is slated to be delivered in 2016. India plans on acquiring modified PAK FA as a part of its Fifth Generation Fighter Aircraft (FGFA) program. It originally planned on buying 166 single-seat and 44 two-seat variants, but this has been reduced to 130-145 single-seat aircraft and the requirement for 45-50 twin-seat fighters has been dropped by 2014. The Russian Defence Ministry plan on purchasing the first 10 evaluation example 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. But Yuri Borisov, Russia's deputy minister of defence for armaments stated in March 2015 that the Air Force will slow PAK FA production and reduce its initial order to 12 jets due to the nation's deteriorating economy. Due to the aircraft's complexity and rising costs, the Russian Air Force will retain large fleets of fourth-generation Sukhoi Su-27 and Su-35S.
The T-50'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 airframe 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 of the T-50 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 T-50 was to initially start flight testing in late 2010; this was delayed until early 2011. On 3 March 2011, the second T-50 completed a 44-minute test flight. The first two prototypes lacked radar and weapon control systems; the third and fourth aircraft, first flown in 2011 and 2012, are fully functional test aircraft. On 14 March 2011, the T-50 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, Russian Prime Minister Vladimir Putin was in attendance. On 3 November 2011, the T-50 reportedly performed its 100th flight. More than 20 test flights were made in the next nine months.
The third prototype, 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. On 22 November 2011, 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 powerplant checks. It differs from the other prototypes in the way it lacks a pitot tube. All 14 test aircraft are scheduled to fly by 2015.
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 T-50 prototypes were flown, with the fifth prototype having its first flight on 27 October 2013; with this flight the program 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 flying prototype T-50 '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 PAK FA is 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 Defense Ministry have openly stated that the aircraft will 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 T-50 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 high cruising speed and normal operating altitude is also expected to give it a significant kinematic advantage over prior generations of aircraft.
The T-50 makes extensive use of composites, comprising 25% of the structural weight and almost 70% of the outer surface. 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. Advanced engines and aerodynamics enable the T-50 to supercruise, sustained supersonic flight without using afterburners. Combined with a high fuel load, the T-50 has a supersonic range of over 1,500 km, more than twice that of the Su-27. In the T-50'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.
The T-50 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 aligned at several specific angles in order 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 IRST 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, but not all, 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 T-50'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 T-50's stealth features cites an average RCS of the aircraft of approximately 0.1-1 square meters. However, like other stealth fighters, the T-50'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 T-50 due to its physical size. However, such radars are also large, susceptible to clutter, and are less precise.
Pre-production and initial production batches of the T-50 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 by the engines. 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 T-50 from 2020 onward will be equipped with a more powerful engine known as the izdeliye 30, a clean sheet design engine that will supersede the 117. NPO Saturn and MMPP Salyut are competing to supply this definitive second stage engine. Compared to the 117, the new powerplant will have increased thrust and fuel efficiency, greater reliability, and lower costs. The izdeliye 30 has fewer fan and compressor stages than the 117, thus reducing the number of parts compared to its predecessor. The engine is designed to produce approximately 107 kN (24,050 lbf) of dry thrust and up to 167 kN (37,500 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. The new powerplant is designed to be a drop-in replacement for the 117 with minimal changes to the airframe.
The T-50 has two tandem main internal weapon bays each approximately 4.6 m (15.1 ft) long and 1.0 m (3.3 ft) 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 T-50'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 (660 lb) and the UVKU-50U for ordnance weighing up to 700 kg (1,500 lb). The aircraft has an internally mounted 9A1-4071K (GSh-301) 30 mm cannon near the right LEVCON root.
For air-to-air combat, the T-50 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, two large izdeliye 810 beyond-visual-range missiles can be carried 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 (550 lb) KAB-250 or 500 kg (1,100 lb) 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 T-50 can carry stores on its six external hardpoints. PAK FA chief designer Alexander Davydenko has said that there is a possibility of the installation of BrahMos supersonic cruise missile on the PAK FA and its FGFA derivative; only one or two such missiles may be carried due to heavy weight of the BrahMos.
The T-50 has a glass cockpit with two 38 cm (15 in) 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), and Moscow-based Geofizika-NV provides a new NSTsI-V helmet-mounted sight and display for the ZSh-10 helmet. 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 T-50 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 (66 lb) 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 23 km.
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 (Russian: Активная фазированная антенная решётка, Aktivnaya Fazirovannaya Antennaya Reshotka, Russian: 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. 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 systems information to be significantly enhanced.
The radar will reduce pilot load and make use of a new data link to share information between aircraft. The T-50 will have secure communication links to share data with all other friendly aircraft in the area, as well as airborne and ground-based control points. In 2012 ground tests of the N036 radar began on the third T-50 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 UOMZ 101KS Atoll electro-optical system includes 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. The 101KS-O infrared countermeasure system has sensors housed in turrets mounted on the dorsal spine and forward fuselage and uses laser-based countermeasures against heat-seeking missiles. The Atoll complex also includes the 101KS-U ultraviolet missile warning sensors and 101KS-N navigation and targeting pod.
101KS-V infra-red search and track
The 929th State Flight Test Centre (GLITS) received its first T-50 prototype for further testing and state trials on 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 then started in May 2014.
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 Defense Minister Anatoly Serdyukov said that Russia and India would jointly build the export version of the T-50 starting in 2020. In 2013, United Aircraft Corporation president Mikhail Pogosyan said that the Russian PAK FA and the Sukhoi/HAL FGFA will use "identical onboard systems and avionics".
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.
Navalized Sukhoi T-50 PAK FAs will be deployed on the Russian aircraft carrier Admiral Kuznetsov and future Russian aircraft carriers. There will be a competition between the Sukhoi, Mikoyan and Yakovlev design bureaus to choose the new naval aircraft.
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.
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".
- Crew: 1
- Length: 19.8 m (65.0 ft)
- Wingspan: 13.95 m (45.8 ft)
- Height: 4.74 m (15.6 ft)
- Wing area: 78.8 m2 (848.1 ft2)
- Empty weight: 18,000 kg (39,680 lb)
- Loaded weight: 25,000 kg (55,115 lb) typical mission weight, 29,270 kg (64,530 lb) at full load
- Max. takeoff weight: 35,000 kg (77,160 lb)
- Powerplant: 2 × NPO Saturn izdeliye 117 (AL-41F1) for initial production, izdeliye 30 for later production thrust vectoring turbofan
- Dry thrust: 93.1 kN / 107 kN (21,000 lbf / 24,300 lbf) each
- Thrust with afterburner: 147 kN / 167 kN (33,067 lbf / 37,500 lbf) each
- Fuel capacity: 10,300 kg (22,700 lb)
- Maximum speed:
- Range: 3,500 km (2,175 mi) subsonic
- 1,500 km (930 mi) supersonic
- Ferry range: 5,500 km (3,420 mi) with one in-flight refueling
- Service ceiling: 20,000 m (65,000 ft)
- Wing loading: 317–444 kg/m2 (65–91 lb/ft2)
- Saturn 117: 1.02 (1.19 at typical mission weight)
- izdeliye 30: 1.16 (1.36 at typical mission weight)
- Maximum g-load: +9.0 g
- Guns: 1× 30 mm (1.181 in) 9A1-4071K (GSh-301) cannon in right LEVCON root
- Air to air loadout:
- Air to ground loadout:
- Air to sea loadout:
- 4× Kh-35
- 2× K-74M2 or 2× izdeliye 300
- Hardpoints: Six external hardpoints.
- Sh121 multifunctional integrated radio electronic system (MIRES)
- 101KS Atoll electro-optical system
- Related development
- Aircraft of comparable role, configuration and era
- Related lists
- The new fighter's control systems, avionics and cockpit will be designed on the basis of the Su-35BM's systems.
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|Wikimedia Commons has media related to PAK FA.|
- General information
- PAK FA - GlobalSecurity.org
- Sukhoi T-50 PAK FA fighter aircraft - airrecognition.com
- KnAAPO page on the T-50
- PAK FA T-50
- United Aircraft Corporation promotional video
- "Wings of Russia" documentary (Russian)
- PAK-FA patent document
- News reports and articles
- FARNBOROUGH 2008: Russian air force to receive Sukhoi PAK FA - to be equivalent of the F-22 Raptor
- Article from India Times
- Article on Flight International website with artistic image of PAK FA from NPO Saturn (4 April 2007)
- Brazil, Russia to build jet fighter, Marco Sibaja, Associated Press
- The Russian Air Force's Super Weapon: Beware the PAK-FA Stealth Fighter, Dave Majumdar, The National Interest, Nov 26, 2014
Flight videos and photos:
- on YouTube
- on YouTube
- Photos of the first and second prototype of PAK FA (Т-50) in flight (2010-2011).