While the Sukhoi PAK FA/T-50 fifth generation fighter aircraft was being developed, the Russian Federation Air Force looked to a radically re-designed variant of the tried and tested Su-27 family of combat aircraft to fill its near term requirement for a new advanced multi-role combat aircraft to supplement its fleet of older generation combat aircraft, a number of which were being modernized. This new variant of the Su-27 family was given the label of the Su-35. The new Su-35S with the NATO reporting name ‘Flanker E’, is described by Sukhoi as a 4th ++ generation combat aircraft that utilizes technologies developed for 5th generation aircraft; in effect a bridge between the Su-27SM3 4th generation and the PAK FA/T-50 5th generation aircraft.
The Sukhoi Su-35 (Russian: Сухой Су-35), single-seat, twin-engine, supermaneuverable multirole fighter. Supermaneuverability is the ability of aircraft to maintain pilot control and perform maneuvers in situations and ways exceeding those that are possible by pure aerodynamic mechanisms.
The first variant was designed during the 1980s, when Sukhoi sought to upgrade its high-performance Su-27, and was initially known as the Su-27M. Later re-designated Su-35, this derivative incorporated aerodynamic refinements with increased manoeuvrability, enhanced avionics, longer range, and more powerful engines. The first Su-35 prototype, converted from a Su-27, made its maiden flight in June 1988. More than a dozen of these were built, some of which were used by the Russian Knights aerobatic demonstration team. The first Su-35 design was later modified into the Su-37, which possessed thrust vectoring engines and was used as a technology demonstrator. A sole Su-35UB two-seat trainer was built in the late 1990s that strongly resembled the Su-30MK family.
In 2003, Sukhoi embarked on the Sukhoi 35 programme. The Russian Air Force has ordered 98 production units, designated Su-35S, of the newly revamped Su-35. Both Su-35 models are marketed to many countries, including Brazil, China, India, Indonesia, and South Korea; China ordered the Su-35 in late 2015. Sukhoi originally projected that it would export more than 160 units of the second modernized Su-35 worldwide.
In 2003, even as Russia aimed to export the Su-27M, Sukhoi launched a project to produce a fighter to bridge the gap between upgraded variants of the Su-27 and Su-30MK, and Russia’s fifth-generation Sukhoi PAK FA. The project’s aim was a second modernization of the Su-27 airframe (hence its classification as a “4++ generation fighter”) by incorporating several characteristics that would be implemented on the PAK FA. Additionally, the aircraft was to be an alternative to the Su-30 family on the export market. The design phase was to take place until 2007, when it would be available for sale. It was later reported that the programme was launched due to concerns that the PAK FA project would encounter funding shortages. The project’s in-house designation is T-10BM (Bolshaya Modernizatsiya, “Big Modernization”) while the aircraft is marketed as the Su-35.
While the aircraft maintains a strong superficial resemblance to the Su-27, the airframe, avionics, propulsion and weapons systems of the Su-35 have been thoroughly overhauled. Technological advancements have produced more compact and lighter hardware, such as the radar, shifting the centre of gravity to the aircraft’s rear. The IRBIS-E Radar performance characteristics (Manufacturers Data) are detailed below:
- In elevation: +/- 60 deg.;
- In azimuth: +/- 120 deg.
The number of detected targets is 30.
The number of simultaneously fired upon air targets is up to 8.
Air to Ground mode:
- Mapping in SAR (Synthetic Aperture Radar) mode with less than 1 meter resolution.
- Real beam mapping in DBS (Doppler Beam Sharpening) mode;
- Ground moving target selection;
- Tracking of up to four targets;
- Tracking of one ground target preserving air sector surveillance.
The radar system has a projected service life of not less than 6,000 hours equating to 30 years of service.
Su-35S uses the N135 Irbis passive antenna array with electronic scanning radar for improved locating. The radar can also map the ground using a variety of modes, including the synthetic aperture mode. The Irbis-E is complemented by an OLS-35 optoelectronic targeting system that provides laser ranging, TV, Infra-red search and track (IRST) functionality. The Su-35 is compatible with a multitude of long- and short-range air-to-air missiles, precision and unguided air-to-ground weaponry that include missiles, fuel-air bombs and rockets. A maximum weapon payload of 8 tonnes can be carried on the fourteen hardpoints. The fighter may use missiles with a range of up to 300 km.
These improvements removed the need for canards and saw the abandonment of the “tandem triplane” featured on several Su-27 derivatives. Also omitted was the Su-27’s dorsal airbrake, which was replaced by differential deflection of the vertical stabilizers. Other aerodynamic refinements include a height reduction of the vertical stabilizers, a smaller aft-cockpit hump, and shorter rearward-projecting “sting”.
The reinforced airframe sees extensive use of titanium alloys, increasing its durability to some 30 years or 6,000 service hours (equal to that of the IRBIS E radar), and raising the maximum takeoff weight to 34.5 tonnes. Internal fuel capacity was increased by more than 20% to 11.5 tonnes, and could be raised to 14.5 tonnes with the addition of drop tanks; in-flight refueling can also be used to extend missions.
Sukhoi has overhauled the avionics suite, at the heart of which is the information management system that enhances man-machine interaction. The system, which has two digital computers, collects and processes data from various tactical and flight-control systems and presents the relevant information to the pilot through the two main multi-function displays, which, together with three secondary MFDs, form the glass cockpit. The aircraft features many other upgrades to its avionics and electronic systems, including digital fly-by-wire flight-control system, and the pilot is equipped with a head-up display and night-vision goggles.
The Su-35 is powered by a pair of izdeliye (Product) 117S (AL-41F1S) turbofan engines. Developed jointly by Sukhoi, NPO Saturn and UMPO, the engine is a heavily upgraded AL-31F variant, and draws on the design of the fifth-generation PAK FA’s Saturn 117 (AL-41F1) engines. Its thrust output is estimated at 142 kN (31,900 lbf), 20 kN (4,500 lbf) more than the Su-27M’s AL-31F. It has a service life of 4,000 hours, compared to the AL-31F’s 1,500; the two engines feature thrust-vectoring capability. Each thrust vectoring (TVC) nozzle has its rotational axis canted at an angle, similar to the configuration on the Su-30MKI. The thrust vectoring nozzles operate in one plane for pitch, but the canting allows the aircraft to produce both roll and yaw by vectoring each engine nozzle differently. A similar thrust vectoring system is also implemented on the PAK FA.
The engine may give the Su-35 limited supercruise capability, or sustained supersonic speed without the use of afterburners. Radar-absorbent material is applied to the engine inlets and the front stages of the engine compressor to halve the Su-35’s frontal radar cross-section (RCS); the canopy was also modified to deflect radar waves.
Sukhoi Su-35 External Stores load:
In addition to the impressive weapons load of the Su-35, the aircraft is fitted with the GSh-30-1 single-barreled, recoil operated autocannon weighing 46 kg (101 lb). Unlike many postwar cannons, it uses a short recoil action instead of a revolver cannon or Gatling gun mechanism. This results in a reduced rate of fire, but lower weight and bulk.
The GSh-301 has a rate of fire of 1,800 rounds per minute, customarily limited to 1,500 rounds per minute to reduce barrel wear. Despite that, its barrel life is quite short: 2,000 rounds.When firing a continuous burst of 100–150 rounds, the barrel is put under so much stress that it has to be replaced. The gun uses an evaporation cooling system to prevent the detonation of a high explosive round inside a heated barrel. This cooling system consists of a cylindrical water tank around the rear end of the barrel. The GSh-301 is equipped with a unique pyrotechnic mechanism to clear misfires: a small pyrotechnic cartridge is located to the left of the 30mm cartridge chamber. This pyrotechnic cartridge fires a small steel bolt through the side wall of the 30mm cartridge. The hot propellant gases following the bolt into the dud 30mm round ignite the powder charge of that round and firing continues.
The gun’s maximum effective range against aerial targets is 200 to 800 m and against surface or ground targets is 1,200 to 1,800 m.
In combination with a laser rangefinding/targeting system, it is reported to be extremely accurate as well as powerful, capable of destroying a target with as few as three to five rounds. It has been deployed on several different types of fighter aircraft:
- Su-27, Su-30, Su-33, Su-34, Su-35 and Su-37: 1 GSh-301 in starboard wing root (150 rds. ammunition load)
- PAK FA: 1 GSh-301 in right LEVCON root
- MiG-29: 1 GSh-301 in port wing root (150 rds. ammunition load)
- Yak-141: 1 GSh-301 on the belly (120 rds. ammunition load)
- Shenyang J-11, Shenyang J-15, Shenyang J-16: 1 GSh-301 in starboard wing root (150 rds. ammunition load)
- 9A4273 gun pod: 1 GSh-301 flexibly mounted, pod weight 480 kg (150 rds. ammunition load)
During the 2009 MAKS air show, the Russian Defence Ministry signed a US$2.5 billion contract for 64 fighters, which consisted of a 48-aircraft launch order for the Su-35S (“Serial”). The Russian government promised to provide Sukhoi an additional US$100 million in capital, with additional financial assistance from Sberbank and Vnesheconombank, the latter of which was contracted to provide US$109 million to start the production programme.The Su-35S’s estimated price was $40 million each, and the 64-aircraft contract was the largest aircraft order after the collapse of the Soviet Union.All are expected to be delivered by 2015.
In November 2009, KnAAPO started manufacturing the first serial aircraft; Sukhoi estimated that 24 to 30 aircraft would be produced each year from 2010 to 2020.On 11 October 2010, the first production Su-35S had completed general assembly;at this point the preliminary flight test programme had logged 350 flight hours across 270 flights using the two remaining flying prototypes. Sukhoi confirmed that the aircraft had fully met all specifications and parameters, including maximum speed, height, radar detection range and manoeuvrability.The first Su-35S took its maiden flight in May 2011.
Following preliminary tests, the Defence Ministry was expected to initiate state joint tests involving six Su-35s to further scrutinize systems such as weapons.In early 2012, two aircraft were reportedly planned for delivery in 2011, eight in 2012, twelve in 2013 and 2014, and fourteen in 2015.In February 2014, the Russian Air Force received 12 Su-35S aircraft.By 2014, 34 of the 48 aircraft originally ordered had been delivered with the remaining 14 due in 2015.
In March 2015, it was reported that Russia and India signed an agreement to jointly develop a fifth-generation upgrade to the Su-35. A Russian industry source stated that the upgraded Su-35S will cost about US$85 million each.
A contract for another 50 Su-35s was signed in August 2015, but parent company United Aircraft Corporation (UAC) stated in January 2016 that delays in finalizing the order was due to a lack of clarity in Russia’s 2016 federal budget, which was only signed by Russian President Vladimir Putin in mid-December 2015. The fighters will be delivered at a rate of 10 aircraft per year starting in 2016.
Three production Su-27Ms were completed and delivered to VVS in 1996 for testing. They were operated by 929th State Flight Test Center (abbreviated as GLITS in Russian) at Vladimirovka Air Base, Akhtubinsk, performing weapons trials. During one such flights, a weapon pylon, to which a bomb and rocket were attached, fell into a village in Ryazan; nobody was hurt. In 2001, the Air Force decided that the aerobatics team Russian Knights would receive several Su-27Ms, presumably from GLITS and Sukhoi. After pilots from the team undertook conversion course at Vladimirovka AB, the first of five aircraft was delivered to the team in July 2003. It was expected that the Su-27Ms would enhance the flying repertoire of their new owners, but due to various reasons, they were used as a source of spare parts for other aircraft in the demonstration fleet.
In late May 2011, Sukhoi flew the first Su-35S to the Defence Ministry’s 929th State Flight Test Centre at Akhtubinsk prior to states joint tests conducted to prepare the aircraft for operational service with the VVS. Official trials commenced in mid-August with the two Su-35 prototypes, before being joined by production aircraft. As of March 2012, four Su-35S units were involved in such tests, operating alongside the two flying prototypes. These Su-35s had by April and August 2012, completed 500 and 650 test flights, respectively.
On 28 December 2012, Sukhoi delivered a batch of six serial production Su-35S fighters to the VVS. Defence Ministry officials accepted the aircraft at KnAAPO’s manufacturing plant in Komsomolsk-on-Amur, Russia. Five of the six Su-35S delivered in December went to the Gromov Flight Research Institute, where in February 2013 an eighteen-month programme began to test the Su-35’s ability to conduct highly maneuverable short-range combat. The programme consists of three components, which are dogfights; the use of weapons and the ability to evade enemy fire; and the ability to destroy helicopters and unmanned aerial vehicles. State-acceptance trials would conclude in 2015, by which time a second 48-aircraft order is expected to have been signed with the VVS. Another 12 Su-35S fighters were delivered in 2013.
In December 2012, Russian officials commented that the Swifts and Russian Knights aerobatics teams would receive new aircraft to replace the Mikoyan MiG-29 and Su-27, respectively. The Swifts was expected to receive the Su-30SM and the Russian Knights receive the Su-35. Deputy Prime Minister Dmitry Rogozin commented the upgrade was to “show to the world not only the inimitable skill of our pilots, but also the talent of our aircraft designers…” Russian Air Force received another 12 Su-35S fighters on 12 February 2014 to be deployed with an air regiment based in Russia’s Far East.
In January 2016, Russia, for the first time in combat conditions, deployed four Su-35S planes to its Khmeimim base; on 1 February the Russian defence ministry said the aircraft had begun to participate in the Russian air operations in Syria.
Since the early 1990s, an extensive sales arrangement of the Su-35 to China has been discussed. Sukhoi officials, in 1995, announced their proposal to co-produce the Su-35 with China, contingent on Beijing’s agreement to purchase 120 aircraft. However, it was alleged that the Russian Foreign Ministry blocked the sale of the Su-35 and Tupolev Tu-22M bombers over concerns about the arrangements for Chinese production of the Su-27.
In 2006, China was showing interest in the modernized Su-35, and was negotiating with Moscow for a purchase of the fighter. At the 2007 MAKS air show, a number of Chinese delegates were seen taking photos and videos of the Su-35 prototypes. In November 2010, Russia, through Rosoboronexport, was ready to resume talks with China on the sale of the Su-35. China reciprocated in 2011 by presenting a proposal on the purchase of the fighter.
In March 2012, the Russian media reported that the two countries were in final contract negotiations for 48 Su-35s; the remaining obstacle is reportedly Moscow’s demand that Beijing guarantee proper licensing for its Su-35 production. China denied this deal because it did not want the Su-35, but only shown slight interest in its 117S engine; at the 2012 Zhuhai Air Show Russia approached China with its 117S engine in a failed attempt to sell Su-35.
In late 2012, it was reported that China wanted to purchase only 24 units, which was less than what Russia deemed to be worthwhile, thus stalling negotiations. By late 2012, the negotiations resumed, this time involving 24 aircraft. During the next three years, negotiations would prove to be protracted, with several false reports claiming that a deal had been reached between the two countries; for example, in March 2013, it was reported that both sides had signed an initial agreement for 24 Su-35s and four submarines prior to Chinese President Xi Jinping’s visit to Russia. Negotiations concluded in November 2015, when a contract for 24 fighters worth $2 billion, was signed. The first aircraft will be delivered to China in 2016. One motive for China’s purchase of the Su-35 is its thrust-vectoring 117S engine; while China has recently developed modern fighters, its engines still lag behind Russia and the West despite heavy investments by China in domestic engine programs during recent years to catch up. According to Russian National Defense magazine, China will not order additional Su-35s but will instead focus on its domestic fighter programs especially its fifth generation fighters.
In May 2006, it was reported that Venezuela planned to purchase dozens of Su-30 and Su-35 fighters, and as many as 100 T-90 tanks. There were unconfirmed reports in October 2008 that the Venezuela government had ordered 24 Su-35s for the Venezuelan Air Force. In July 2012, Venezuelan President Hugo Chávez repeated his interest in acquiring the Su-35 fighters. This procurement seems unlikely now, given the catastrophic collapse of the Venezuelan economy.
In January 2015, North Korea has expressed interest in the fighter. But due to the international sanctions imposed on North Korea the delivery of fighters is unlikely in the near future.
Also in September 2015, Indonesia’s Ministry of Defence selected the Su-35 to replace the Indonesian Air Force’s aging F-5E Tiger II fleet. Indonesian Air Force intends to buy 16 Su-35S fighters from Russia. A contract for 10 Su-35S is reportedly to be signed in April 2016.
Vietnam and Algeria are also interested in this aircraft. In February 2015, one of the Su-35 was tested at Tamanrasset Airport in Algeria. According to “Kommersant”, the Algerian military were satisfied with the fighter’s flight characteristics and now Moscow is waiting for a formal application. It is expected that the first phase will focus on the acquisition of at least 12 aircraft.
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