As an air superiority fighter and holder of numerous world records, a participant in spectacular air shows and unparalleled non-stop flights, and an aircraft which still continues to amaze the world with its top flight performances, the Su-27 is often called the Russian enigma of the 1980s. This aircraft opened the door to the 21st century for our tactical aviation. Designed in 1977 by the Sukhoi Experimental Design Bureau (EDB), the Su-27 came along as the first implementation of the vast and manifold development scenario of fourth generation tactical aircraft for the then Soviet, now Russian, Air Force. 
   The Su-27 has embraced in its design the latest achievements of EDB designers and scientists of defense research institutes. 
   Today, after a lapse of many years, one can see the results of this grand project, which may be the most challenging

in the history of combat aviation. They have materialized in the whole Su family, which now comprises the Su-27UB, Su-30, Su-33, Su-32FN, Su-35, and, finally, the Su-37 aircraft. 
 The new multirole all-weather superagile fighter Su-37 (registration number 711) with thrust vector control (TVC) represents a logical step forward in the steady implementation by the Sukhoi EDB of a development program of fourth and fifth generation of tactical aircraft from the basic Su-27 fighter for the Russian Air Force. As announced by General Designer Mikhail Simonov, the new fighter is related to "the fourth with two pluses" generation. This is the latest, although far from the last, Sukhoi's development. 
   Drawing on previous research and new progressive technologies, the EDB has produced, jointly with engine, systems, avionics and armament designers, a fighter which is likely to stay in service until 2015 - 2020. 
   Alexander Kotelkin, Director General of the Rosvoorouzhenie State Corporation, repeatedly declared at the latest international arms exhibitions that due to a large volume of export deliveries of the Su-27s and their derivatives, Sukhoi will rank among the world's top three leading exporters of fighters in the next decade. 
   The seriousness of this statement was confirmed by the first flight of the Su-37 prototype on April 2, 1996, with test pilot Yevgeny Frolov, Hero of Russia, at the controls. This was followed five months later by a demonstration flight of this aircraft at the prestigious Farnborough '96 air show, where it amazed the spectators with its maneuverability. 
   Introducing the new machine, Mikhail Simonov emphasized that, unlike the American X-31, this was no experimental specimen, but rather a prototype of the series production aircraft. It has a standard configuration of the Su-35 multirole fighter, can carry up to 14 air-to-air missiles and up to 8,000 kg of ordnance. 
   The following features clearly set this aircraft apart from the others: 
   - capability to deliver a preemptive strike at any air target, including hard-to-detect ones; 
   - exceptionally high performance; 
   - phenomenal agility; - multichannel redundancy and algorithmic protection of all information and aiming systems; 
   - ground target attack standoff range capability; 
   - terrain following and ground obstacle avoidance capability; 
   - automated group actions during attacks at air and ground targets; 
   - ability to counteract enemy ECM and optronic means; 
   - automation of all phases of flight and combat employment. 
   The Su-37's powerplant comprises two experimental TVC turbofans, type AL-31FU. The engine was developed by the Lulka-Saturn company team, led by General Designer Victor Chepkin, and is a derivative of the twin-shaft AL-31F turbofan installed on the Su-27. It has a modular design, which allows for replacement of its nozzle, afterburner, mixer, low-pressure (LP) turbine and compressor, and gearbox as part of its post-warranty servicing. One can also repair or replace the blades of the first stage of the LP compressor and all stages of the HP compressor. The axis-symmetric swivelling nozzle is secured to the annular swivel and can be moved in the pitch plane with the aid of two pairs of hydraulic jacks. 

 
   

Depending on a maneuver to be performed, the nozzles can be deflected both synchronously and differentially. The biggest problem with the implementation of the TVC nozzle concept, that has still not be resolved by the Americans, was to provide the nozzle reversal joint with a seal strong enough to prevent outblast of the gases with a temperature of almost 2,000 oC and pressure of 5 to 7 kgf/cm2. 
   The AL-31F and AL-31FU engines are fully interchangeable; in other words, all the derivatives of the Su-27 and the base aircraft may be powered by the AL-31FU engine. As well as powering the Su-37 fighter, the AL-31FU engine will be first installed on the Su-30MK multirole two-seater fighter. 
   The Su-37 uses the 'unstable integral triplane' layout, which, in combination with the small specific load acting on the wing, high power-to-weight ratio, integral electrical remote control system and powerplant TVC feature, ensures the aircraft superagility, increased range of controlled flight and improved takeoff and landing characteristics. 
   The TVC feature incorporated into the aircraft flight control loop makes it possible to minimize, when required, the flight speed and perform aerobatics at speeds nearing zero without angle-of-attack limitations (hence superagility). 
   According to Mikhail Simonov, the aircraft has virtually no angle-of-attack limitations. It can fly flatwise to the air stream, with its tail forward, i. e., with 90 and even 180 deg angles of attack. It can locate targets with its radars and attack them with its weapons from any position. This feature is extremely important for both air combat and the evasion of enemy missile attacks. 
   The Su-37 multirole fighter is furnished with the full range of onboard systems and equipment, and is a prototype of the series production aircraft. 
   Its avionics equipment comprises an onboard multifunction jamproof forward-looking phased-array radar that can track up to 15 targets at a time, provide target designation, launch and guide several air-to-air missiles fitted with active, passive and IR homing heads, and an optronic fire control and surveillance system. In addition, the onboard avionics equipment is used for mapping, multichannel employment of guided weapons and low altitude flight with avoidance of ground features. 
   The information and control facilities in the pilot's cockpit cover four wide liquid-crystal displays of tactical and flight-navigation data, onboard system monitors and an operating conditions control panel. Information from individual systems may be presented on any display selected by the pilot. One more widescope indicator is installed on the windscreen. 
  

The side short-travel control stick of the aircraft, avionics control handle and strain-gauging engine thrust controls, as well as tactical situation, flight conditions and systems monitors enable the pilot to effectively control the aircraft, systems and weapons. 
   The Su-37 multifunction fighter can carry air-to-air and air-to-surface weapons at its 12 hardpoints. 
   For air combat, the aircraft is fitted with R-73E short-range air-to-air IR homing missiles and RVV-AE air-to-air missiles with active radar guidance. 
   To attack ground and water-surface targets, the Su-37 can carry IR and radar homing missiles. 
   In the opinion of leading western experts, the Su-37 fighter will stay unrivaled for many years to come and take a deserving position on the world arms market. 

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