The Sukhoi Su-27 (Russian: Сухой Су-27) (NATO reporting name: Flanker) is a twin-engine supermanoeuverable fighter aircraft designed bySukhoi. It was intended as a direct competitor for the large United States fourth generation fighters, with 3,530-kilometre (1,910 nmi) range, heavy armament, sophisticated avionics and high manoeuvrability. The Su-27 most often flies air superiority missions, but is able to perform almost all combat operations. Complementing the smaller MiG-29, the Su-27's closest US counterpart is the F-15 Eagle.
There are several related developments of the Su-27 design. The Su-30 is a two-seat, dual-role fighter for all-weather, air-to-air and air-to-surface deep interdiction missions. The Su-33 ‘Flanker-D’ is a navy fleet defence interceptor for use on aircraft carriers. Further versions include the side-by-side 2-seat Su-34 ‘Fullback’ strike variant and the Su-35 ‘Flanker-E’ improved air defence fighter.
In 1969, the Soviet Union learned of the U.S. Air Force's "F-X" program, which resulted in the F-15 Eagle. The Soviet leadership soon realised that the new American fighter would represent a serious technological advantage over existing Soviet fighters. What was needed was a better-balanced fighter with both good agility and sophisticated systems. In response, the Soviet General Staff issued a requirement for a Perspektivnyy Frontovoy Istrebitel (PFI, literally "Prospective Frontline Fighter", roughly "Advanced Frontline Fighter"). Specifications were extremely ambitious, calling for long range, good short-field performance (including the ability to use austere runways), excellent agility, Mach 2+ speed, and heavy armament. The aerodynamic design for the new aircraft was largely carried out by TsAGI in collaboration with the Sukhoi design bureau.
When the specification proved too challenging and costly for a single aircraft in the number needed, the PFI specification was split into two: the LPFI (Lyogkyi PFI, Lightweight PFI) and the TPFI(Tyazholyi PFI, Heavy PFI). The LPFI program resulted in the Mikoyan MiG-29, a relatively short-range tactical fighter, while the TPFI program was assigned to Sukhoi OKB, which eventually produced the Su-27 and its various derivatives. The TPFI program is similar to the American F-X program, which resulted in the F-15 Eagle, while the LPFI program is similar to the Lightweight Fighter program, which spawned the F-16 Fighting Falcon and the Northrop YF-17, which itself led to the F/A-18 Hornet.
The Sukhoi design, which was altered progressively to reflect Soviet awareness of the F-15's specifications, emerged as the T-10 (Sukhoi's 10th delta wing design), which first flew on 20 May 1977. The aircraft had a large delta wing, clipped, with two separate podded engines and a twin tail. The ‘tunnel’ between the two engines, as on the F-14 Tomcat, acts both as an additional lifting surface and hides armament from radar. While being developed, it was spotted by a spy satellite at the Zhukovsky flight test center near the town of Ramenskoe, resulting in the temporary codename of 'Ram-K'. It was believed that the Ram-K was being developed in two versions: a swing-wing fighter similar in function to the Grumman F-14 and a two-seat fixed wing interceptor aircraft which in fact turned out to be the unrelated Mikoyan MiG-31.
The T-10 was spotted by Western observers and assigned the NATO reporting name 'Flanker-A'. The development of the T-10 was marked by considerable problems, leading to a fatal crash on 7 May 1978. Extensive redesigns followed, and a heavily revised version, the T-10S, made its first flight on 20 April 1981. This, too, had considerable developmental problems, leading to another fatal crash on 23 December 1981
The production Su-27 (sometimes Su-27S, NATO designation 'Flanker-B') began to enter VVS operational service around 1984, although manufacturing difficulties kept it from appearing in strength until 1986. The Su-27 served with both the V-PVO and Frontal Aviation. In V-PVO service it was primarily an interceptor aircraft, supplanting older aircraft like the Sukhoi Su-15. Although the Su-27 has some capacity to carry air-to-ground weapons, in Frontal Aviation it was primarily tasked with fighting its way past enemy lines to destroy tanker andAWACS aircraft. The Su-27 retains that role in CIS service, with later marks capable of carrying long-range "AWACS killer" missiles such as the Vympel R-37 and, potentially, the Novator K-100 when it enters production.