Su-27

Flanker In Sky

 

 

 

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HISTORY

 

INTRODUCTION

 

SU-27 FAMILY:

Su-30MK

Su-32/34

Su-35

Su-37

 

 

The SU-27 , a Russian fourth-generation single-seat supersonic fighter, is recognised all over the globe as one of the best combat aircraft of the 20th century. Due to its perfect flight performances and operational characteristics, the fighter is rightfully popular with pilots and technicians. Top piloting capabilities of the Su-27 fighter demonstrated during multiple air shows around the world did not leave anyone indifferent. The Su-27 is in the top lines of the aviation record tables of the International Aircraft Federation. To the date, the Su-27 is a record-holder of 27 world class flight achievements. The Su-27 is the forefather of a combat aircraft family of various functionality, including the Su-27UB trainer, Su-27K ship-borne fighter (Su-33), Su-30 twin-seat interceptor, Su-30MK twin-seat multirole fighter, Su-34 tactical bombers Su-35, Su-37 and other high-manoeuvrability multirole aircraft.

Advavced FrontLine Flights Program

A team of developers from the Kulon Machine-Building Plant headed by Pavel Osipovich Sukhoi initiated in 1969 the development of an advanced new-generation fighter for the Soviet Air Force and Air Defence Forces' aviation. By the mid-seventies, a general concept of the new fighter was formulated in co-operation with a number of science and research institutions. This concept provided for a high-manoeuvrability long-range fighter with a powerful weapons system and a perfect sighting/navigation system that would allow the pilot to participate efficiently in both long-range missile exchange and dogfight. The basic performances of the new fighter were to be of top class globally while a number of characteristics was to exceed those of its American F-15 counterpart the American leadership was reasonably vesting its high hopes in. The design bureau was planning to introduce a number of major innovations and solutions into the design of the new fighter designated T-10.

Birth of T10

Proceeding from the updated and more specific requirements the client set for the tactical fighter of the eighties, Sukhoi started in 1972 developing a preliminary design of the T-10 fighter subsequently followed by the conceptual design stage. During 1970-75, over 15 options of the fighter configuration were given consideration. Those configurations varied not only in general approaches to the problem (integrated or classic configuration) but differed in solutions suggested for individual problems . Finally, preferences were given to the aircraft design with an integrated statically unstable configuration. The Su-27 was to become the first Soviet unstable fighter with longitudinal in-flight balancing to be provided by a fly-by-wire control system. Accepting the longitudinal static instability concept (in other words, "electronic stability") promised a lot of advantages: for the aircraft to balance at a high angle of attack, the leading edge slat's upward deflection was required with its lift being added to the wing lift, which allowed significant improvement of the fighter lift with a minor increase in its drag. Due to the use of the integrated statically unstable configuration, the Su-27 was to acquire outstanding manoeuvrability allowing the fighter altitude changes unavailable to typical configuration fighters and an increase in its range of up to 4,000 km without external fuel tanks. There were no other series-produced fighter in the world boasting similar performances.

T-10-1
The first Su-27 prototype

 

The Su-27 fighter powerplant included two powerful and economical AL-31F bypass turbofan engines producing thrust of 12,500 kg each. They were developed by the Saturn Mechanical Plant headed by Arkhip Mikhailovich Lyulka and supposed to ensure take-off thrust-to-weight ratio exceeding 1. Low specific fuel consumption along with about eight tonnes of fuel stored in internal tanks filling most of the airframe inner space was to ensure required operational range of the fighter.

T-10-1
The first Su-27 prototype

The Su-27 fighter weaponry which included 30 mm high-rate cannon, K-27 medium-range air-to-air missiles and K-73 or K-14 short-range missiles was to be standardised with that of the MiG-29 light tactical fighter. The only difference in armament was the warload carried: while the MiG-29 could house only six missiles, including two K-27 missiles, the Su-27 was capable of carrying eight, including four K-27s, as well as the K-27E improved longer-range radar-homing and heat-seeking missiles.

An integrated weaponry control system of both fighters was substantially standardised and, for the first time in the history of aviation, included two complementing channels - a radar sighting system and an optoelectronic sighting system, as well as a helmet-mounted sight. The sighting system initially designed for the Su-27 fighter had better characteristics. The N001 radar was built by the Phazotron Research and Development Association under the guidance of Victor Grishin. The OLS-27 optics-based detection and ranging system combining an acquisition/tracking IR locator and a laser rangefinder was developed by the Moscow-based Geophysics Central Design Bureau headed by Chief Designer D.Khorol.

The Maiden Flights

Vladimir Ilyushin
test pilot

The Su-27 fighter conceptual and detailed design stages were completed in 1975-1976, and after issuance of required design documentation and drawings, the manufacturing of first prototypes was initiated at the Kulon plant. Unfortunately, Pavel Sukhoi did not live long enough to see the fighter - he died in 1975 to be succeeded by Yevgeny Ivanov. From 1976 on, the Su-27 programme has been under immedeate guidance of Chief Designer Mikhail Simonov. The first prototype designated T10-1 was completed in early 1977. Due to the lack of the Al-31F turbofan bypass engines, the prototype was equipped with two AL-21F-3AI engines - a modified version of the series-production AL-21F-3A engine mounted on other Sukhoi-developed fighters (Su-17, Su-24). After the completion of required ground checks and run-ups, everything was ready for test flights and on 20 May, 1977 Vladimir Ilyushin, Sukhoi's chief pilot, took the T10-1 off the ground for its maiden flight. The first prototype was used to evaluate its key flight performances as well as stability and controllability.

 

The T-10 testing also revealed the failure of the fighter's certain characteristics to match those of the performance specifications. First of all, that was true for the range: the mismatch between the required and actual ranges exceeded 20 percent. The Designer General reported to the ministry that there were two main reasons for non-compliance with certain requirements set in the performance specifications. Firstly, avionics developers failed to meet the weight limits set out in the avionics performance specifications. The summary avionics excessive weight comprised a few hundred kilograms, which, naturally, led to the aircraft's overall weight increase, hampered its manoeuvrability and reduced its range. Secondly, the engine's specific fuel consumption ordered in the performance specifications had not been achieved by the developer either. Truth be told, the issue was settled later when the requirements to the engine's specific fuel consumption were found to be a tall order which could not be met then. In spite of the T-10's considerable deficiencies revealed during the research and flight tests, Yevgeny Ivanov hoped, nonetheless, for possibility to gradually hone that configuration through minor design modifications, fuel capacity increase, etc. Otherwise, Mikhail Simonov was pushing hard for radical aircraft reworking, since as early as in 1976-77 a team of his subordinates in cooperation with the SibNIA scientists developed on their own and later tested in the wind tunnel a new configuration of the airframe devoid of the deficiencies which the previous configuration had in abundance. Justice should be done to M.P.Simonov (who went to work for the Aviation Industry Ministry in 1979 to return to Sukhoi as Designer General in 1983) who managed to persuade the leadership to risk radical change in the configuration of the fighter that had been already undergoing tests by then. With the passage of time, this decision proved to be right and led no matter what to building the aircraft that still - almost two decades later - has been regarded as one of the best warplanes in the world. Having commenced production of the Su-27 in its final configuration, Sukhoi confirmed its reputation of a world leader of aviation industry in line with its old tradition of never fielding mediocre aircraft.

 

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