The Su-37 multirole, all-weather fighter aircraft demonstrator is derived from the family of aircraft based on the Su-27, which was developed in 1977 by the Sukhoi Experimental Design Bureau in Moscow and is in service with the Russian Air Force and a number of other countries. This family also includes the Su-27UB, Su-30, Su-33, Su-32FN and Su-35, and has the Nato codename Flanker. The Russian Air Force is currently operating two Su-37 aircraft.
During the Su-35 flight test programme, active controls during dogfighting maneuvers could not be attained; thus Sukhoi explored the application of thrust-vectoring nozzles to give fighters better dogfighting attributes. The first Su-37, converted from the eleventh Su-35, made its maiden flight in April 1996 at Zhukovsky. It was joined by a second prototype in 1998. Throughout the program, the Su-37 publicly demonstrated its attributes at numerous air shows, performing maneuvers impossible to complete with normal flight control methods, among which was a 360° somersault. Despite its potential advantages, the Su-37 did not enter production; it has instead remained as a technology demonstrator for updated Su-27 family aircraft such as the export Su-30 and the modernized Su-35.
Design and development
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).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. The first Su-27M prototype (T-10S-70) made its maiden flight on 28 June 1988. Changes from the Su-27 include canards, upgraded engines, new radar, and a digital fly-by-wire flight-control system. Later Su-35 prototypes featured glass cockpits and modified vertical stabilizers. The Su-35's construction made significant use of composites, including aluminium-lithium (Al-Li) alloy. 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.
The Su-37 could perform the 180° "Frolov Chakra", demonstrating itssupermaneuverability
In 1995, the eleventh T10M prototype, T10M-11, was delivered to Sukhoi's experimental workshop to be outfitted with exclusive systems. Built byKnAAPO, its structure has increased carbon-fibre and Al-Li content. Installed was the 2D thrust-vectoring Lyulka AL-31FP, an interim measure pending the availability of the AL-37FU (Forsazh Upravleniye, "afterburner-controlled").The 3D thrust-vectoring Lyulka AL-37FU was still in development. 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-31FP is only variable in pitch, plus or minus 15°. 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°.
Cockpit
The cockpit is fitted with four liquid crystal displays for tactical and navigation data, onboard system monitors, and operating conditions control panel. Avionics for the aircraft were produced by Kronstadt, St Petersburg.Instead of traditional analogue instruments, the cockpit has four T-form Sextan Avionique (Thales) LCD multi-function displays (MFD). The pilot, who is provided with a head-up display (HUD), sits on the K-36DM ejection seat inclined 30° to help counter the effects of high g-forces. The pilot steers with a side-stick and pressure-sensing throttles. 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.Painted in a disruptive sand and brown scheme, the aircraft was given the code 711 Blue, later changed to 711 White. Its maiden flight occurred at Zhukovsky on 2 April 1996, withYevgeni 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.Frolov was joined by Igor Votintsev, and for the next twelve days, the two had amassed twelve flights between them.
The Su-37 can carry up to 14 air-to-air missiles and up to 8000kg of ordnance. The twelve external hardpoints can carry air-to-air missiles, air-to-surface missiles, bombs, rockets and an ECM (electronic countermeasures) pod. The aircraft is fitted with one GSh-301 30mm gun with a maximum rate of fire of 1,500 rounds a minute.
The aircraft can be equipped with Vympel R-73E short-range air-to-air missiles with infrared terminal homing and RVV-AE long-range air-to-air missiles with active radar guidance. R-73E (Nato codename AA-11 Archer) is an all-aspect, close-combat missile capable of engaging targets in tail-chase or head-on mode at altitudes between 0.02km and 20km, and target g-load to 12g. The Vympel RVV-AE (AA-12 Adder) air-to-air missile, also known as the RR-77, can intercept targets at speeds up to 3,600kph and altitudes from 0.02 to 25km.
The Su-37 can be fitted with air-to-surface missiles such as the Kh-25 (AS-12 Kegler) short-range missile and Kh-29 (AS-14 Kedge) with a 317kg penetrating warhead.
The aircraft is fitted with a multifunction, forward-looking, NO-11M pulse Doppler phased array radar, which can track up to 15 targets simultaneously and provide target designation and guidance to air-to-air missiles. NO-11M is manufactured by NIIP, the Tikhomirov Scientific Research Institute of Instrument Design.
There is also a rear-looking NIIP NO-12 radar and optronic fire-control and surveillance system.
There are also systems for terrain-following and terrain-avoidance, mapping and multichannel employment of guided weapons.
Engines
The Su-37 is powered by two AL-31FU TVC (thrust vector control) turbofan engines. This engine was developed by the Lyulka Engine Design Bureau (NPO Saturn) and is a derivative of the AL-31F twin-shaft turbofan engine on the Su-27. The modular design includes a four-stage, low-pressure (LP) compressor; a nine-stage, high-pressure (HP) compressor; annular combustion chamber and single-stage LP and HP turbines, afterburner and mixer. Each engine provides 83.36kN thrust and 142kN with the afterburner and is steerable from -15° to +15° along the vertical plane.
The thrust vector control is fully integrated into the digital flight control system. The TVC nozzle can be deflected both synchronously and differentially, depending on manoeuvre. The nozzle is connected to the annular swivel and can be moved in the pitch plane by two pairs of hydraulic jacks. The thrust vector control allows manoeuvres at speeds nearing zero without angle-of-attack limitations. The vectoring controls can be operated manually by the pilot or automatically by the flight control system.
Operational history
A modernized Su-35Ѕ performing at the Moscow International Aviation and Space Show in 2009. This aircraft features thrust-vectoring technology, similar to the Su-37
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 Yevgeni Frolov. 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. 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.It appeared at that year's Moscow International Aviation and Space Show and Dubai International Defence Exhibition, as well as the 1998FIDAE air show in Chile; for the latter two the Su-37 appeared under the enigmatic designation, "Su-37MR".
In 1998, there was a report about a second Su-37 (T10M-12) which was similarly converted before making its first flight on 23 March the same year. But this was not true. The No.712 was never converted to the Su-37 specifications, this plane was used in Aktubinsk for weapon and radar tests. Later, the No.712 (with the No.703 and all three serial produced planes, bort No. 86, 87, and 88) added to the Russkie Vityazi demo team, repainted. Flight tests and demonstrations at air shows continued until 2000. In 2001, 711 was outfitted with AL-37FU engines 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 program; the fault was later traced to structurally damaged right horizontal stabilizer, caused by the extensive load during high g post-stall tight turns. 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, which feature similar improvements such as improved avionics and radar systems, and thrust vectoring engines.
Performance
The Su-37 all-weather multirole fighter aircraft can fly at a maximum speed of 2,440km/h. The range and service ceiling of the aircraft are 3,700km and 18,000m respectively and the aircraft weighs around 18,500kg.