Sukhoi Su-37 - Design and Development

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.

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. Installed was the 2D thrust-vectoring Lyulka AL-31FP, an interim measure pending the availability of the AL-37FU (Forsazh Upravleniye, "afterburner-controlled"). 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°. 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°.

The fire-control system was also improved. An upgraded Phazotron 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. 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.

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. 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). 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.