The introduction in the mid-1970s of the USAF F-15 Eagle and F-16 Fighting Falcon put the then Eastern bloc fighter pilots at a distinct disadvantage. The deployment of the Su-27 Flanker and MiG-29 Fulcrum in the mid-1980s leveled the playing field. Designed as a high performance fighter with a fly-by-wire control system, and the ability to carry up to 10 AAMs, the highly maneuverable Su-27 is one of the most imposing fighters ever built.
The MiG-29 is superficially similar in layout to the larger Su-27, and unlike counterpart American fighters which are easily distinguished, a close attention to design details is needed to distinguish the two Russian fighters:
- The most striking difference is the Su-27's signature centerline fuselage stinger, which protrudes well aft of the engine exhaust, and is entirely absent on the MiG-29, though this feature may not be apparent from all angles.
- The vertical stabilizers on the MiG-29 are canted outward, while those of the Su-27 are vertical.
- Conversely, the air intakes on the MiG-29 are canted inward, while the air intakes on the Su-27 are vertical.
- The Mig-29 fuselage sits entirely above the air intakes, engine pods and exhaust beneath the wings, whereas on the Su-27 there is a distinct droop of the forward fuselage below the upper edges of the air intakes.
The first 'Flanker-A' prototypes flew on 20 May 1977. By the early 1980s, Sukhoi's T10-1 prototype was the subject of much scrutiny by Western intelligence agencies, who dubbed it Flanker-A. As the prototype evolved into the Su-27 or Flanker-B production model, word of its potential as a fighter spread as well. Flanker-B Su-27S, which was the original version to enter service, entered service in 1984. The initial production single-seater was referred to as the Su-27S, allowing the designation Su-27 to refer to any or all variants in the family of aircraft. However, it should be remembered that the designation of Su-27 is perfectly valid for the Su-27S, and probably in wider usage.
There are three factories - IAPO Irkutsk Aviation Production Association, KNAAPO Komsomolsk-on-Amur Aviation Production Association, NAPO Novosibirsk Aviation Production Association - that produced Su-27 aircraft. During the Cold War, IAPO was responsible for twin-seat versions and KnAAPO for single-seat variants. After the end of the Cold War, when orders were scarce and competition keen, both factories developed their own aircraft designs in both configurations.
The Su-27 airframe was manufactured using an integral configuration with the wing and fuselage forming a single aerodynamically lifted frame. Its longitudinal sections in the form of the wing airfoil ensure high aerodynamic efficiency and high lift coefficient while manoeuvring. To increase the aircraft manoeuvrability, it is designed statically unstable with artificial stability provided by the remote control system. The fighter is fitted with the analogue quad-redundant fly-by-wire system. The wings are mid-mounted and semi-delta with square tips. The wing has drooping leading edges and flaperons. The Leading-Edge Root Extension (LERX) extends downward and forward of the wing roots. The vertical tail is twin-finned with rudders. The horizontal tail is a differential tailplane and consists of two all-moving outer wings. The tail fins are swept-back, tapered with square tips, and mounted outboard of the engines. The flats are mid-mounted, swept-back, and tapered.
The fuselage is rectangular from the air intakes to the tail. The undercarriage is a three-leg one with a forward retracted mono-wheel strut. The aircraft construction is made of aluminium alloys with the use of titanium. The fuel system consists of five tanks located under the fuselage, in the centre and outer wings. There are two turbojet engines in the fuselage. There are square, diagonally-cut air intakes mounted under the wings alongside the fuselage. The nose is pointed and there is a bubble canopy. The crew cockpit is fitted with the K-36DM Series 2 ejection seats.
The program to develop the Su-27 as a new-generation plane was the USSR's major national defence program in the '70s-'80s. Its implementation was financed on a large scale, which had the most favourable effect on the development of many establishments in the national aircraft industry and related areas, making it possible to retrofit many production facilities and introduce a great number of new technologies.
The Su-27 program set up a large network of subcontractors across the country. Large-scale introduction of leading-edge technologies was the rule for all of the plane's systems.
The plane's powerplant comprises two AL-31F turbofans developed by the Design Bureau of A.M. Lyulka. In terms of specifications and performance, these are new-generation engines with superior weight, thrust and fuel consumption characteristics achieved through a dramatic improvement in compressor gas-dynamic behaviour and operating temperature before the turbine. It was only possible to achieve such characteristics by harnessing promising new materials and technologies: new titanium alloys, heat-resistant steels, single-crystal vanes, special coatings, and other new features.
For the plane as a whole, it was vitally important to stay within the weight limits so that the Su-27's various systems had to be extensively reengineered to incorporate new components. For example, it was decided, to meet the specifications for the control system and reduce the size and weight of its assemblies, to incorporate in the plane's design the USSR's first mass-produced hydraulic system with operating pressure increased up to 280 kg/cm², and a radically new type of steering linkage, with power and distribution centres separated into individual blocks.
The Su-27's avionics were developed based on large-scale introduction of digital processing using an onboard computer and the principle of extensive integration of various systems by function; for instance, the fire control system incorporated, in addition to a target search and track radar channel (multi-purpose onboard radar), an independent information channel, i.e., an optical search and tracking station. As part of the goal-oriented retrofitting program, the Su-27 received a specially developed new-generation guided missile of medium (K-27E) and short (K-73) range.
All the above made it possible to create a combat aircraft capability which can be used to effectively engage the very best foreign-made combat planes. All the subsequent history of the Su-27 series validates this conclusion.
The development of the Su-27 fighter plane was completed in the early 1980s, and the plane subsequently set more than 40 world records of altitude and take-off-speed. Between 1986 and 1990, using a specially configured prototype aeroplane T10-15, which became known as P-42, the design bureau's test pilots established 41 IAF-registered world records of rate-of-climb and flight altitude, some of the records being absolute.
In June 1989, the Su-27 and Su-27UB were for the first time shown abroad, at the Le Bourget air show. The design bureau's test pilots V.G. Pugachov and Ye.I.Frolov demonstrated to the international aviation community the superior manoeuvrability of Sukhoi planes. From that day on, Su-27 type planes have been participating in the most prestigious international aviation events, invariably demonstrating the highest level of achievement in the Russian aircraft industry.
One of the little known facts about the Flanker is that its super-manoeuvrability reduces its visibility on radar screens. Mikhail Simonov, the aircraft’s legendary designer, explains: “Super-manoeuvrability should be looked at as a system of manoeuvres for close aerial combat. Once the pilot receives a signal that his plane is being tracked by enemy radar, the first thing he needs to do is to go vertical. While gaining altitude and losing speed the aircraft starts to disappear from the screens of radars that use the Doppler effect.
“However, the opponent is no fool either and will counter by pitching his aircraft upward as well. By that time our plane is going vertical and its speed approaches zero. But all Doppler radars can recognise only a moving target. If the aircraft speed is zero or simply low enough to prevent the enemy radar from calculating the Doppler component, for the enemy our aircraft will disappear. He may still be able to track us visually, but he will not be able to launch a radar-guided missile (either active or semi-active), simply because the missile’s seeker would not pick-up the target."
Another proof of the plane's superior combat performance is the Su-27's commercial success in the global marketplace. Starting in 1991, the production facilities in Komsomolsk-on-Amur and Irkutsk have been producing export variants of the Su-27: the Su-27SK and Su-27UBK. Models of these types have since 1992 been exported to China, Vietnam, Ethiopia and Indonesia. Sukhoi in 1997 signed an estimated $180-million contract with Vietnam to supply six Su-27 (of which two Su-27SK and four Su-27UB). It supplied four of them in 1996 [and two were destroyed when the freighter carrying them crashed into an apartment block in Irkutsk]. Indonesia ordered two Su-27SK and two Su-30MK aircraft, which were delivered in September 2003, and has plans to order eight more.
China also bought a license for the production of its own Su-27 fighters. Su-27SKs have since 1998 been produced as the F/J-11 in China under licence in accordance with intergovernmental agreement. The first licensed-production plane, assembled in the town of Shenyang, was flight tested on 16th December 1998.
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