The Sukhoi Su-35 (Russian: Сухой Су-35; NATO reporting name: Flanker-E) is a designation for two separate, heavily-upgraded derivatives of the Su-27 air-defence fighter. They are single-seat, twin-engine, highly-maneuverable aircraft, designed by Sukhoi and built by Komsomolsk-on-Amur Aircraft Production Association (KnAAPO).
The first variant was designed during the 1980s as an upgrade of the Su-27, and was initially known as the Su-27M. This derivative incorporated canards and a multi-function radar that transformed the aircraft into a multi-role aircraft, and was structurally reinforced to support its heavier weight. The first prototype made its maiden flight in June 1988. As the aircraft was not mass produced due to the collapse of the Soviet Union, Sukhoi re-designated the aircraft as Su-35 to attract export orders. At the same time, the fifteen aircraft produced were used for tests and demonstrations; one example had thrust vectoring engines installed, and the resultant Su-37 was used as a technology demonstrator. A sole Su-35UB two-seat trainer was also built in the late 1990s that strongly resembled the Su-30MK family.
In 2003, Sukhoi embarked on a second modernization of the Su-27 to serve as an interim aircraft awaiting the development of the Sukhoi PAK FA (Su-57) program. Also known as Su-35, this derivative has a redesigned cockpit and weapons-control system compared to the Su-27M, and features thrust-vectoring engines in place of the omitted canards. The type made its first flight in 2008. Although the aircraft was designed for export, the Russian Air Force in 2009 became the launch customer of the aircraft, the production version of which is designated Su-35S. China's People's Liberation Army Air Force is the sole foreign user of the aircraft. Other countries are reportedly in discussions with Russia about the possible purchase of the Su-35, among which is Indonesia, whose government is expected to sign a contract in the near future.
Design and development
Upgraded Su-27
The first aircraft design to receive the Su-35 designation had its origins in the early-1980s, at a time when the Su-27 was being introduced into service with the Soviet Armed Forces. The definitive production version of the Su-27, which had the internal designation of T-10S, started mass ("serial") production with KnAAPO in 1983. The following year, this Su-27 version reached initial operational readiness with the Soviet Air Defence Forces. Having begun work on an upgraded Su-27 variant in 1982, Sukhoi was instructed in December 1983 by the Soviet Council of Ministers to use the Su-27 as the basis for the development of the Su-27M (T-10M). Nikolay Nikitin would lead the design effort throughout much of the project's existence, under the oversight of General Director Mikhail Simonov, who had been the chief designer of the Su-27.
While sharing broadly the blended wing-body design of the Su-27, the Su-27M is visibly distinguished from the basic version by the addition of canards, which are small lifting surfaces, ahead of the wings. First tested in 1985 using an experimental aircraft, the canards, in complement with the reshaped wing leading-edge extension, redirected the airflow in such a way so as to eliminate buffeting at high angles of attack and allowed the airframe to sustain 10-g manoeuvres (as opposed to 9 g on the Su-27) without the need for additional structural reinforcement. More importantly, when working with the relaxed-stability design and the accompanying fly-by-wire flight-control system, the aerodynamic layout improved aircraft's manoeuvrability; it enabled the aircraft to briefly fly with its nose past the vertical while maintaining forward momentum. Because of this, theoretically, during combat the pilot could pitch the Su-27M up 120 degrees in under two seconds and fire missiles at the target. Other notable visible changes compared to the T-10S design included taller vertical tails, provisions for in-flight refuelling and the use of two-wheel nose undercarriage to support the heavier airframe.
Besides the increase in manoeuvrability, another feature that distinguished the Su-27M from the original design was the new weapons-control system. The centrepiece of this system was the multi-function N011 Bars (literally "Panther") phased-array radar with pulse-Doppler tracking that allowed it to detect targets below the horizon. First installed on the third prototype, the radar transformed the Su-27M from simply being an air defence fighter into a multi-role aircraft capable of attacking ground targets. Compared to the N001 Mech ("Sword") Cassegrain-attenna radar of the Su-27, which could only direct a missile towards one target at a time, the new radar could track fifteen targets and direct missiles towards six of them simultaneously. The extra weight of the N011 radar at the front of the aircraft necessitated the addition of the canards; engineers would only later discover the aerodynamic advantages of these devices. In addition, an N012 self-defence radar was housed in the rearward-projecting tail boom. Other changes to the aircraft included the use of marginally-uprated turbofan engines, as well as the increased use of lightweight composites and aluminium-lithium alloys in the aircraft's structure.
Testing and demonstration
In 1987, Sukhoi started converting the first prototype (designated T10M-1) from a T-10S airframe at its experimental plant in Moscow. Like several subsequent aircraft, the first prototype lacked the many physical alterations of the new design. It made its first flight after conversion on 28 June 1988, piloted by Oleg Tsoi, followed by the second prototype in January 1989. Following the conversions of the two Su-27M prototypes, the actual production of the aircraft was transferred to the country's Far East where it was carried out by Komsomolsk-on-Amur Aircraft Production Association (KnAAPO). The third aircraft (T10M-3), which was the first new-built Su-27M and first to be constructed by KnAAPO, made its first flight in April 1992. By then, the Soviet Union had disintegrated, and the ensuing economic crisis in Russia throughout the 1990s meant that the original plan to mass-produce the aircraft between 1996 and 2005 was abandoned, with the aircraft to serve as experimental test-beds to validate the canards, the flight-control system and thrust-vectoring technology.In total, two prototypes, ten pre-production and three production aircraft were constructed by 1995; the production aircraft were delivered in 1996 to the Russian Air Force for weapons testing.
By the time of the disintegration of the Soviet Union, Sukhoi had been demonstrating the Su-27M to senior defence and government officials. With its debut to a Western audience at the 1992 Farnborough Airshow, the company redesignated the aircraft as Su-35. The aircraft subsequently made flying demonstrations overseas in an effort to attract export orders, starting in November 1993 with Dubai, where Viktor Pugachev flew it in a mock aerial engagement with an Su-30MK in front of spectators. The aircraft thereafter flew in Berlin and Paris, and would be a regular feature at Moscow's MAKS Air Show. The Russian government cleared the aircraft for export during Sukhoi's unsuccessful sales campaign in South Korea during the late 1990s and early 2000s; the company also marketed the aircraft to Brazil, China and the United Arab Emirates.
As the flight test programme of the Su-27M proceeded, engineers discovered that the pilot failed to maintain active control of the aircraft during certain manoeuvres, such as the Pugachev's Cobra. The eleventh Su-27M (T10M-11) was therefore installed with thrust-vectoring engine nozzles in 1995, and the resultant Su-37 technology demonstrator made its first flight in April 1996. It also tested the enhanced N011M Bars-M radar, as did the twelfth developmental Su-27M. The Su-37's ability to maintain a high angle of attack while flying at close to zero airspeed attracted considerable public attention. It later received different engines and updated fly-by-wire controls and cockpit systems for evaluation.
Apart from the single-seat design, a two-seat aircraft was also constructed. Working in cooperation with Sukhoi, KnAAPO's own engineers designed the Su-35UB so as to combine thrust-vectoring engines with features of the Su-27M. Modified from an Su-30MKK airframe, the aircraft made its first flight in August 2000, and afterwards served as an avionics test-bed. While the original Su-27M never entered mass production due to a lack of funding, Sukhoi refined the Su-27M's use of canards and the Su-37's thrust-vectoring technology and later applied them to the Su-30MKI two-seat fighter for the Indian Air Force.The tenth Su-27M (T10M-10) also served as a test-bed for the Saturn 117 engine that is intended for the Sukhoi Su-57 (previously known under the acronym "PAK FA") jet fighter.
| A modernized Su-35S of the Russian Air Force | |
| Role | Multirole air superiority fighter |
|---|---|
| National origin | Soviet Union / Russia |
| Design group | Sukhoi Design Bureau |
| Built by | Komsomolsk-on-Amur Aircraft Production Association |
| First flight | Su-27M: 28 June 1988 Su-35S: 19 February 2008 |
| Introduction | 2014 |
| Status | In service |
| Primary users | Russian Air Force People's Liberation Army Air Force |
| Produced | Su-27M: 1987–1995 Su-35S: 2007–present |
| Number built | Su-27M: 15 Su-35S: 58, 4 for export |
| Unit cost |
US$40–65 million (Su-35S)
|
| Developed from | Sukhoi Su-27 |
| Variants | Sukhoi Su-37 |
sources: wikipedia
Sukhoi Su-35
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