Read this one the other day and though you guys would like it.
Program Dossier: Su-57
The Su-57, also known as the PAK FA (Perspektivny Aviatsionny Kompleks Frontovoy Aviatsii-"Prospective Airborne Complex of Frontline Aviation"), is a Russian fifth-generation fighter. Current aircraft are fitted with a pair of Saturn AL-41F1 (izdeliye 117) engines. Production aircraft are expected to use the izdeliye 30 (item 30) turbofan, which is under development. The aircraft was developed by the Sukhoi Design Bureau and manufactured by the Komsomolsk-on-Amur Aircraft Production Association (KnAAPO).
Features
Overall Design
The Su-57 is intended to replace the Su-27/30 Flanker family of aircraft as both an air-superiority and strike fighter. The design features a full array of fifth-generation capabilities: stealth; supercruise; super maneuverability and advanced, integrated sensors.
The airframe is a blended wing-body design, resembling the Su-27 in that the core of the structure is a "centroplane"-a long-chord, deep-section inner wing to which the rest of the airframe components (the forward fuselage, widely separated engine nacelles, wings and tail surfaces) are attached. Compared to the Su-27, however, the centroplane is deeper between the engines to accommodate internal weapon bays.
The main challenge in the structural design was to provide space for tandem weapon bays running the entire length of the center section. This ruled out the structural concept used on the Lockheed Martin F-35 and F-22, which have multiple full-depth bulkheads carrying the wing loads, because this forces all the weapon bays to be ahead of the wing. The centerline structure on the T-50 has to be quite shallow, so that designing it to resist peak wing bending loads would be a very difficult challenge. The solution on the T-50 was to design the centroplane section as a stiff, integrated structure with two sets of full-depth longitudinal booms, located at the outer edges of the nacelles and at the wing-to-centroplane junction. These are connected by multiple (the patent drawing shows eight) span wise spars that also carry the wing attachment fittings. The result is a structure that spreads the bending loads over the centroplane and reduces the peak loads at the centerline.
Stealth Technology
The first details of the T-50's stealth technology emerged in late December 2013, when Sukhoi published several of its relevant patents. The documents claim the program's goal was to reduce the radar cross-section (RCS) of the T-50 to an "average figure of 0.1-1 m2," compared to approximately 10-15 m2 for the Su-27.
Extensive platform alignment is employed to reduce the number of directions in which radar waves reflect off the surface. The side fuselage, air intake lateral edges and vertical tails all are inclined at the same angle. The sweep angles of the forward Centro plane, wing leading edge and horizontal tail leading edge are all the same. The air intakes are rear-swept rhomboids, as on the F-22. There are a few openings in the surface of the aircraft-such as the boundary-layer bleeds on the sides of the air intakes and other openings on the upper fuselage immediately aft of the cockpit-but these are covered with a thick grid, featuring a mesh of less than one quarter of the wavelength of a search radar, which reduces the reflections from these uneven surfaces. Doors for the landing gear and weapon bays employ saw tooth edges on their front and rear.
The structure is largely comprised of carbon-fiber, for less inherent radio-reflectivity, and coated with a paint of ferro-magnetic nanoparticles of varying thickness (likely thicker at high-scattering areas). Gaps between the airframe elements are filled with conductive sealants. Scattering from the cockpit is prevented by a 10-nanometer-thick, layered coating of indium-tin-oxide and gold.
Sensor and communication systems have been designed to minimize their contribution to RCS. PAK FA has five radar arrays, all of which are angled to deflect incoming radar waves away from their sources. The radar covers permit passage of their own signals but block other frequencies. The edges of the array compartments are lined with radar-absorbing "curtains" to reduce possible signal leaks.
Engines
The T-50 prototypes are currently flying with a pair of NPO Saturn 117 turbofans, very similar to the 117S engines on the Su-35S, which themselves are modernized versions of the AL-31FP powerplants that equip the Su-27/30 family. The engine can produce 19,842 lb. of dry thrust and 32,000 lb. of thrust with full afterburner. The engines, combined with the T-50's sharply swept delta wings and high fineness ratio, mean the aircraft will have no difficulty in cruising at supersonic speed without afterburning, up to the temperature limits of its engines. It is believed that the target maximum speed of the T-50 is around Mach 2. The goal originally was Mach 2.35, but this was reduced to Mach 2.1 and then to the current figure, compared to Mach 2.25 for the Su-35S. The main reason for the difference is that the T-50 uses more composite materials in its primary structure than the Su-35S, which makes heavy use of titanium.
The AL-41F1s will serve as an interim power plant with the more advanced clean sheet izdeliye 30 expected to enter production in the 2020s. The new engine will be lighter than the current AL-41F1, at 3,197 lb. (1,450 kg) compared to 3,527 lb. (1,600 kg), and is expected to produce at least 16 to 17 metric tons of afterburning thrust (35,274 to 37,479 lb.). Special consideration was made to reduce the radar returns of the engine's face by using glass-fiber plastic inlet guide vanes.
Avionics
A core feature of fifth-generation fighters is the ability to process vast quantities of data gathered by multiple sensors into actionable information for pilots. This capability is referred to as sensor fusion, and it greatly expedites a pilot's decision-making cycle. Sensor fusion is among the most difficult aspects of fifth-generation development. In recognition of this fact, Sukhoi's design bureau is integrating the avionics subsystems for the Su-57. Historically, the instrument companies have been responsible for subsystem integration. Sukhoi developed an information management system for the Su-57 that will run on two onboard computers. The Su-57's principal avionic subsystems are the radars, electro-optical/infrared (EO/IR) systems and self-protection suite.
The Su-57's N036 Byelka (Squirrel) radar was developed by the Moscow-based Tikhomirov Scientific Research Institute of Instrument Design (NIIP). The system consists of five active electronically scanned arrays (AESAs) that together provide 270 deg. of continuous coverage. The largest array is the N036-01-1 X-band antenna, mounted on the nose and tilted up 15 deg. Comprising 1,552 transmit/receiver (T/R) modules, the array likely has impressive range across a 120-deg. field of regard, although Sukhoi has yet to specify it. Two more X-band arrays, each designated N036B-1-01, are mounted on the sides of the ventral nose under the front cockpit and angled down 15 deg.
The N036B-1-01 contains a 500 mm-wide elliptical array of 358 T/R modules on a hexagon-shaped mount. These side-looking arrays are believed to be intended for ground surveillance, as they are horizontally polarized instead of vertically polarized (as a forward-facing array is), but they also would allow the Su-57 to detect aerial targets up to 135 deg. off the nose axis, albeit at shorter range than the much larger forward array. Two L-band antennas, designated N036L-1-01, are embedded in the wings' leading edges and are used for IFF and target detection, likely improving the system's ability to detect lower-RCS targets. The system has a built-in N036Sh Pokosnik IFF System and can operate in air-to-air and air-to-ground modes simultaneously.
The Su-57 is protected from enemy radars, in addition to its stealth, by a Sh121 electronic warfare suite. The system includes a Kaluga Scientific Research Institute for Radio Technology (KNIRTI) L402 Himalaya electronic countermeasures (ECM) system that emits through two sets of arrays that operate in different frequency ranges: the N036 and a series of dedicated ECM emitters distributed around the aircraft, including one in the tail cone.
Weapons
The PAK FA has four internal weapon bays. The two main tandem weapons bays are recessed between the aircraft's engine nacelles and run along the length of the aircraft's ventral fuselage surface. Each bay is approximately 2 ft. 11 in. wide and are 14 ft. 5 in. long. The secondary "quick reaction" weapon bays are mounted in oblong underwing fairings adjacent to the aircraft's landing gear bay doors. An internal GSh-301 or 9A1-4071K 30mm cannon with 260 rounds is mounted in the starboard wing root. Two new internal ejection racks will be carried within the Su-57's main internal bays. The lighter UVKU-50L can accommodate munitions weighing up to 661 lb. (300 kg) and the heavier UVKU-50U can carry munitions up to 1,543 lb. (700 kg).
Russia is in the process of developing multiple new weapons for the PAK FA including three new air-to-air missiles (AAMs), precision-guided munitions (PGMs) and stand-off cruise missiles. The Su-57 can be fitted with six external pylons (four underwing and two fuselage) that can be used when low observability is not a concern.
The primary air-to-air weapon being developed for the Su-57 is the Vympel R-77M (izdeliye 180) medium range AAM, which is equivalent to the Raytheon AIM-120D. The Su-57 is expected to carry up to four R-77Ms internally with two missiles in each of the main weapon bays. The R-77M is a highly modified version of the existing R-77 (NATO reporting name AA-12 Adder). Russia also is developing shorter and longer-range AAM complements to the R-77M for the PAK FA. The Vympel K-74M2 (izdeliye 760) short-range AAM is Russia's latest short-range IR guided missile. The K-74M2 is capable of off-boresight shots at angles greater than 60 deg., as well as lock-on-after-launch engagements. The missile features a Karfagen-760 seeker with a range of 9 to 12 mi. (15-20 km) and a maximum kinematic range of 25 mi. (40 km). A single K-74M2 can be carried in each one of the quick reaction bays. The longer-range izdeliye 810 is an evolution of R-37M (izdeliye 610M), which was developed as a long-rang
e missile for the MiG-31BM interceptor. The izdeliye 810 will be miniaturized to fit within the confines of the PAK FA's internal bays. The original K-37M missile weighs 1,124 lb. (510 kg), is more than 13 ft. long and has a range of 124 mi. (200 km).
Several new air-to-surface munitions are being developed for the Su-57, including anti-radiation missiles and stand-off cruise missiles. The Raduga Kh-58UShK is a supersonic anti-radiation missile with a 328-lb. (149-kg) warhead. The Kh-58UShK is a highly modified variant of the Kh-58 and features folding fins and a redesigned, compact airframe suited to fit within internal weapon bays. The Kh-58UShKE (export) version has a range of 152 mi. (245 km). The Kh-59MK2 is a low observable, GPS/GLONASS-guided cruise missile with an electro-optical digital scene-matching area correlation (DSMAC) terminal seeker. The Kh-59MK2 is powered by an izdeliye 37-04 (TRDD-50B) turbojet engine and has a range of at least 180 mi. (290 km), though some Russian sources believe the missile's actual range exceeds 310 mi. (500 km)
Production and Delivery Status
Sukhoi officials originally stated they expect to produce 1,000 Su-57s over the next 35-40 years, including approximately 200 for Russia, 200 for India and 600 for export countries. As of the time of this writing, Russia is the only nation to commit to purchasing the aircraft. The VKS plans to field 76 Su-57s by 2028.
Russia
In 2013, the MoD planned to declare initial operational capability (IOC) and begin full rate production of the Su-57 in December 2016. The earlier "State Armament Program 2020" (GPV 2020), which was written in 2012, called for the purchase of 60 PAK FAs by 2020. An additional 150-160 aircraft would be purchased by 2025. In March 2015, Deputy Defense Minister Yuri Borisov announced that Russia may purchase more Su-30s and Su-35s by 2020 instead of T-50s. In December of that year, the Russian MoD signed a contract for 50 more Su-35S. In August 2017, Borisov claimed that the Su-35 was not inferior to the first-stage Su-57 configuration aircraft.
In August 2018, the MoD signed a contract for the first pair of production Su-57S aircraft. A subsequent order for 13 production examples was announced in January 2019, with deliveries beginning in 2020. A portion of these airframes will be of the stage two configuration with izdeliye 30 engines. Subsequent reporting by Russian sources stated 16 production-configuration Su-57s were on contract, rather than 15, prior to June 2019. In May 2019, Sukhoi began assembly of the first production model Su-57.
On June 27, 2019, Vladimir Putin signed 46 defense contracts worth 1 trillion rubles ($15.9 billion in 2019 dollars), including the procurement of 76 Su-57s through 2018-2027 GPV. The new contract includes the previous 16 Su-57s already on contract, effectively adding 60 new Su-57s. Putin announced the contract will cut the cost of the Su-57 by 20% and Russian Industry and Trade Minister Denis Manturov confirmed all aircraft would be delivered by 2028. The 76 aircraft will comprise a mix of stage 1 and stage 2 aircraft.
India Fifth-Generation Fighter Aircraft (FGFA) / Prospective Multirole Fighter (PMF)
In January 2003, Russia and India signed a letter of intent for the development of a Prospective Multirole Fighter (PMF), which India would refer to as the Fifth Generation Fighter Aircraft (FGFA). An intergovernmental agreement was signed in November 2007 concerning the joint development of the FGFA by both Sukhoi and India's Hindustan Aeronautics Ltd. (HAL). The two countries signed a $295 million, 18-month preliminary design contract in December 2010. Russia planned to hand over its first prototypes in 2017, with the Indian Air Force (IAF) declaring IOC in 2022. Eventual production would have been established in HAL's facility in Nasik, Western India. The FGFA program ultimately collapsed after years of disputes regarding India's industrial participation, Russian demands for renewed Indian funding, Indian requests for substantial modifications-to the effect of creating an entirely new aircraft-and PAK FA development delays.
India originally planned to acquire 214 FGFAs-166 single-seaters and 48 of a two-seat version-which would be developed by HAL. Indian companies also were supposed to have a 50% share in the development work. In October 2012, New Delhi reduced its planned buy to 144 fighters, all single-seaters. The reduced buy also resulted in a reduction in India's share of the design work to 25% and HAL's role has been considerably reduced.
Russia informed India it sought a second development contract worth $10 billion-which was later raised to $11 billion with a $5.5 billion Indian contribution in mid-2013. The IAF raised serious technical and performance-based concerns with the Russians over a series of meetings between December 2013 and January 2014. On Jan. 15, 2014, the Deputy Chief of the Air Staff, the IAF's top procurement official, said "the FGFA's engine was unreliable, its radar inadequate, its stealth features badly engineered, India's work share too low, and the fighter's price would be exorbitant by the time it enters service." A few months later in June 2014, T-50-5 caught fire while landing in front of an Indian delegation in Russia.
By the end of 2015, India had reduced its buy to 127 single-seat aircraft, its industrial participation had been reduced to 13% and the country stopped making FGFA payments altogether. Subsequent negotiations in January 2016 produced a compromise in which India would pay $3.7 billion over a seven-year period. IAF officials again requested 50 modifications to the baseline Su-57 design during these negotiations. In 2017, the IAF published a report that was deeply critical of the Indian government's involvement with the FGFA program. The IAF reportedly concluded that the FGFA would be inferior to the F-35 and the FGFA's maintenance costs would be much higher than projected, repeating the shortfalls of the Su-30MKI program.
In early 2018, India withdrew from the FGFA program. Political factors also are believed to have contributed to the demise of the FGFA program. Within the past few years, senior IAF officials have sought to promote the procurement of Western aircraft at the expense of India's traditional Russian suppliers. IAF officials also were concerned that funding the development of the FGFA would limit the IAF's ability to credibly fund its tender for 110 fighters following the IAF's purchase of 36 Rafales for [euro]7.8 billion ($8.7 billion) in 2015.
