The Sukhoi Su-37 (NATO reporting name: Flanker-F) nicknamed "Terminator" inside Sukhoi, is an experimental single-seat,supermaneuverable multirole jet fighter, designed by Sukhoi. A further development of the original Su-27 "Flanker", it was modified from the first-generation Su-35 (formerly "T10M") prototypes. The Su-37 features an upgraded avionic suite and fire-control system, but its most notable additions are the thrust-vectoring nozzles. Only two prototypes were converted.

During the Su-35 flight test programme, active controls during dogfighting maneuvers could not be attained. At the same time, Sukhoi was exploring the application of thrust-vectoring nozzles for fighter jets, giving it better dogfighting attributes. The first Su-37, converted from the eleventh Su-35, performed its maiden flight in April 1996 at Zhukovsky. It was joined by a second prototype in 1998. Throughout the entire program, the Su-37 demonstrated its potential to prospective operators at numerous air shows, performing maneuvers which were previously thought as impossible, among which was a 360° somersault. Despite its potential tactical advantage, the Su-37 did not enter production, and instead remained as a technology demonstrator for updated Su-27 family aircraft such as the export Su-30 and the Su-35BM.

Design and developmentEdit

The earliest records on thrust-vectoring technology research within Sukhoi began in 1983. The design bureau studied two-dimensional (2D) vector nozzle, which was believed by the West to be the best way of controlling thrust. Sukhoi modified an Su-27UB-PS twin-seater with a 2D nozzle to verify the feasibility of this kind of nozzle. However, the design bureau's General Designer, Mikhail Simonov, believed asymmetrical nozzles (3D) to be more suitable. At the request of Sukhoi, experiments on both types of nozzles were carried out by the Siberian Aeronautical Research Institute (SibNIA).[2][3]

Meanwhile, Sukhoi was busy with the T10M (later renamed Su-35 in 1993) program, which was a comprehensive upgrade over the Su-27. The T10M would incorporate aerodynamic modifications, improved avionics and armament, and have a better propulsion system, designed to give it greatly-enhanced agility.[4] The first Su-27M prototype (T-10S-70) made its maiden flight on 28 June 1988.[5]Changes from the Su-27 include canards, upgraded engines, new radar, and a digital fly-by-wire flight-control system.[6] Later Su-35 prototypes featured glass cockpits and modified vertical stabilizers.[4] The Su-35's construction made significant use of composites, including aluminium-lithium (Al-Li) alloy.[7] The aircraft, like the Su-27, could perform the previously-unattainable "Pugachev's Cobra" and tailslide, but during these low-speed maneuvers, active controls could not be achieved because the flight control surfaces were ineffective.[2]

In 1995, the eleventh T10M prototype, T10M-11, was delivered to Sukhoi's experimental workshop to be outfitted with exclusive systems. Built by KnAAPO, its structure has increased carbon-fibre and Al-Li content.[9] Installed was the 2D thrust-vectoring Lyulka AL-31FP, an interim measure pending the availability of the AL-37FU (Forsazh Upravleniye, "afterburner-controlled").[4] The Al-31FP, in fact, is a hybrid version combining the Al-31F and the vectoring nozzle of the Al-37FU. Being fitted with a 2D vector nozzle, the Al-31FU is only variable in pitch, plus or minus 15°.[10] The engine not only incorporates a new-generation 2D TVC nozzle but also is resistant to engine surge even during inverted and flat spins, giving better reliability and maneuverability even when the angle of attack is 180°.[11]

The fire-control system was also improved. An upgraded Phaztron N-011M Zhuk-M pulse-Doppler radar was fitted. It can scan 180° horizontally and 55° up and down, and is capable of tracking 20 aerial targets and guiding eight air-to-air missiles. In the aircraft's tail sting is an N-011M rearward facing radar, which has a 120° view horizontally and in elevation. The Su-37 also features an upgraded electronic warfare support measures package.[12] It can carry air-to-air and air-to-surface weapons on 12 hardpoints. The vast range of weapons, of which the Su-37 can carry 8,000 kg (17,600 lb), is supplemented by the 150-round 30 mm GSh-301 cannon.[13]

Instead of traditional analogue instruments, the cockpit has four T-form Sextan Avionique (Thales) LCD multi-function displays (MFD). These display air data/navigation, systems status, weapons/systems selection and tactical situation information.[14] The pilot, who sits on the K-36DM ejection seat inclined 30° to help counter the effects of high g-forces, is provided with a head-up display (HUD).[14][15][16] The pilot steers with a side-stick and pressure-sensing throttles.[14] The two-grip flying control configuration was designed to prevent the pilot from losing contact with the controls when the aircraft is engaged in fast vectored-thrust maneuvers. Both the fixed throttle and the side-stick controller provide secure points for the pilot to brace his hands.[16]

edit Operational historyEdit

Painted in a disruptive sand and brown scheme, the aircraft was given the code 711 Blue, later changed to 711 White.[17][18] Its maiden flight occurred at Zhukovsky on 2 April 1996, with Yevgeni Frolov at the controls. The nozzle was locked fully aft throughout the flight, and it was not until the sixth flight that tests on the thrust-vector nozzles commenced.[16][19][20] Frolov was joined by Igor Votintsev, and for the next twelve days, the two had amassed twelve flights between them.[18]

The 711 Blue was demonstrated to the press at Zhukovsky in spring 1996, by which time it was re-designated Su-37. Its debut to the general public came in September that year at the Farnborough Airshow, piloted by Sukhoi test pilot Yevgeny Frolov.[4] A big talking point of the show was its performance of the "Super Cobra", when the aircraft pitched up to 180°, literally flying tail first, albeit for only a few seconds; this maneuver evolved into the 360° "Frolov Chakra" somersault.[9][18] The following year, the aircraft arrived on the fifth and last day of the Paris Air Show to perform five aerial displays, the fourth of which was marred by a minor incident when the emergency undercarriage extension handle was moved, preventing gear retraction.[22] It appeared at that year's MAKS Airshow and Dubai International Defence Exhibition, as well as the 1998 FIDAE air show in Chile; for the latter two the Su-37 appeared under the enigmatic designation, "Su-37MR".[23]

In 1998, a second Su-37 (T10M-12) was similarly converted[1] before making its first flight on 23 March the same year.[24] Flight tests and demonstrations at air shows continued until 2000. In 2001, 711 was outfitted with the AL-31F and updated fly-by-wire flight control system and avionics. In December 2002, 711 crashed during a ferry flight, effectively bringing an end to the programme; the fault was later traced to a software malfunction.[25][26][27] The Su-37 did not reach the production stage, although by mid-2000, Sukhoi introduced several modernizations of Su-27, such as Su-30MKI and second generation Su-35, the Su-35BM, which feature similar improvements such as improved avionics and radar systems, and thrust vectoring engines.[21][28]

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