The Sukhoi Su-27

v1.0.2 / 01 jun 02 / greg goebel / public domain

* While the Russia that has emerged from the ruins of the old Soviet empire remains disorganized and shaky, the Russian military still retains some impressive weapons. One of the more impressive is the Sukhoi Su-27 fighter, a large combat aircraft that is one of the mainstays of Russian air power. This document describes the history and details of the Su-27.

[5] ADVANCED SU-27M (SU-35, SU-37)
[6] STRIKE SU-27IB (SU-34, SU-32FN)


* In 1969, the United States Air Force (USAF) selected the McDonnell Douglas F-15 as the winner of the service's "Fighter Experimental (FX)" program. Faced with a formidable new American threat, the Soviet government immediately issued a request for a new fighter of their own to match the F-15, under the designation "Perspektivnyi Frontovi Istrebitel (PFI / Prospective Frontal Fighter)". The program was also apparently referred to as the "anti-F-15".

The PFI was specified as a long-range interceptor to replace older aircraft of that category, such as the Tupolev Tu-128 "Fiddler", the Sukhoi Su-15 "Flagon", and the Yak-28P "Firebar". As a secondary requirement, it was to be used as an escort for long-range strike aircraft such as the Su-24 "Fencer", or as a long-range intruder to attack Western air assets such as tankers or airborne warning & control systems (AWACS) deep in hostile territory.

The PFI requirements specified an agile aircraft with a top speed of 1,450 KPH (783 knots); a combat radius of 1,700 kilometers (916 nautical miles) at high altitude and 500 kilometers (270 nautical miles) at low altitude; and an operational ceiling of 18,300 meters (60,000 feet). The PFI was to be able to operate from what the Red Air Force (VVS) called a "Third Class Airfield", with a runway length of 1,200 meters (3,940 feet).

The Mikoyan and Sukhoi design bureaus (OKBs) both began work on the PFI specification. The Yakovlev OKB also initiated work on the requirement, but dropped out to pursue the Yak-141 vertical takeoff fighter. The Sukhoi design team was led by Yevgeny Ivanov and his deputy, Oleg Samolovich, with inputs from OKB Director General Pavel Sukhoi.

Following aerodynamic information provided by the TsAGI (Tsentral'nyi Aerogidrodynamichesky Institut / Central Aerodynamic & Hydrodynamic Research Institute), both the Sukhoi and MiG OKBs designed aircraft with a twin-finned, high-winged, tailed-delta configuration and using a new armament and fire-control system being implemented by other design bureaus. The main armament was to be the "K-25" missile, which was apparently similar to the US Sparrow, but in fact never reached production.

It soon became obvious that the agility and range requirements of the PFI specification were incompatible, and so, under the urging of MiG OKB Director General Artem Mikoyan, the PFI specification was split into "Logiky PFI (LPFI / Lightweight PFI)" and "Tyazholyi PFI (TPFI / Heavy PFI)" specifications.

This also mirrored American thinking, since the US Air Force had followed their F-15 program with a relatively low-cost "lightweight fighter" effort that resulted in the F-16 Fighting Falcon.

One of the designs the Mikoyan OKB had investigated proved suitable for the LPFI specification, and became the Mikoyan "MiG-29". The Sukhoi design proved a match for the HPFI specification, and was designated "T10", since it was the tenth delta ("Teugoinyi / Triangular") winged aircraft designed by the Sukhoi OKB.

The T10 was a big aircraft, with large volume for carrying fuel and systems, and its elegantly-curved wing was blended into the fuselage to improve lift. Long leading-edge root extensions (LERX) were fitted to allow good handling at high angles of attack. The twin fins provided maximum controllability and directional stability.

The T10 was a twin-engined aircraft, initially fitted with Saturn-Lyulka AL-21F-3 engines providing 11,200 kilograms (24,700 pounds) thrust each, with the intakes under the wing roots. The first T10, designated "T10-1" or "Blue 10", flew on 10 May 1977, with Sukhoi's chief test pilot, General Vladimir Ilyushin, at the controls.

Vladimir Ilyushin is the son of Sergei Ilyushin, who founded the Ilyushin OKB, but is a well-known and highly respected figure in his own right. The T10 was the 143rd aircraft he had piloted, including almost every Soviet type and even the B-25 Mitchell, the Cessna A-37, and the Northrop F-5E. Ilyushin was extremely pleased with the T10.

Blue 10 was immediately spotted by a US reconnaissance satellite, with NATO giving the new type the provisional name of "Ram-K", since Western intelligence did not know the name for the secret Zhukovsky flight center and simply referred to it as "Ramenskoye", a nearby town. Some overimaginative analysts thought it had variable geometry wings, and a few years would pass before that myth would be discarded.

Other analysts suggested that it was a copy of a Western aircraft, much to the irritation of the aircraft's designers. To be sure, the Ram-K had features similar to those of Western fighters that had preceded it, but those Western fighters in some cases had features of various Soviet fighters that had preceded them in turn. In reality, similar aerodynamic and mission requirements tended to lead to similar design solutions.

To an extent, however, the "copycat" accusation wasn't based completely on snobbery, since the USSR, particularly in Stalin's day, pragmatically did not hesitate to borrow, copy, or steal useful foreign technologies. In fact, the MiG and Sukhoi OKBs occasionally accused each other of copying as well, though similarities between their respective efforts were inevitable, as they were working from the same TsAGI aerodynamic recommendations.

The second T10 prototype, the "T10-2", was lost on 7 May 1978, with the pilot, Yevgeny Soloviev, killed while ejecting. A total of four prototypes were built by the Sukhoi OKB in the bureau's workshops, while five more were built at the state factory at Komsomolsk between 1980 and 1982. The state factory also provided subassemblies for the four prototypes developed at the Sukhoi workshops. As Western intelligence learned more about the aircraft, it was given the name of "Flanker-A".

The prototypes varied in detail, with two of those developed at the bureau workshops featuring production "AL-31" engines. Two more prototypes were under construction when the decision was made to redesign the aircraft, as tests showed the T10 prototypes were not meeting performance specifications. As the T10 stood, it was no match for the American F-15.

* The redesigned aircraft was designated the "T10S", with the "S" optimistically standing for "Series". Roughly ten T10S prototypes were produced, with some of them built new and some rebuilt from T10 prototypes. Initial T10S prototypes were similar to the T10, with incremental changes progressing through the series to the final production configuration.

The development effort continued to have more than its share of troubles. The first T10S prototype, the "T10S-1", rebuilt from the "T10-7", first flew on 20 April 1981 with Vladimir Ilyushin as pilot but was lost due to a fuel system problem, with Ilyushin ejecting safely.

The second prototype, the "T10S-2", rebuilt from the T10-12, broke up in flight on 23 December 1981, killing its pilot, Alexander Komarov. Another prototype, the "T10S-7", was wrecked when the pilot, Nikolai Sadovnikov, tried only too successfully to duplicate the fatal last flight of the T10S-2, but Sadovnikov managed to get the aircraft back down on the ground even though it had lost much of its left wing. It turned out that the two accidents were caused by defective leading-edge flaps that broke away. The flaps were promptly redesigned.

After these nasty teething problems were resolved, the test pilots were wildly enthusiastic about the performance and handling of the T10S, particularly in comparison to the T10. Unfortunately, after the flight problems of the aircraft were generally resolved, manufacturing problems remained. The production aircraft, designated "Su-27", only began to enter service in small numbers in 1986. NATO gave the production aircraft the designation "Flanker-B".

* While the manufacturing problems were being resolved, some of the prototypes were being used to set flight records. The "P-42" was converted from the T10S-3 by stripping it of all unnecessary equipment, and was used to successfully challenge records held by the similarly stripped-down F-15 "Streak Eagle". The flights were performed by Sukhoi test pilots Viktor Pugachev and Nikolai Sadovnikov. One of the flights set a record climb to 15,000 meters (49,200 feet) in 70.33 seconds, breaking the Streak Eagle's record by seven seconds.

This was cause for satisfaction, given the rocky path of the aircraft's development, and encouraged believers that the efforts would pay off after all. Another prototype, the "T10S-10", was stripped down and modified to challenge the 500 kilometer (270 nautical mile) closed circuit speed record, but it appears it was never actually used in such an attempt.



* The production Su-27 clearly retained much of the look of the original T10, but the changes were visible and obvious. The most apparent change was the adoption of a larger wing that featured straight edges, replacing the curved wing of the T10. Other visible changes included:

Of course, the production Su-27 had armament and operational avionics systems. Armament included:

In mature production aircraft, the wingtip rails could be removed and replaced with Sorbtsiya electronic countermeasures (ECM) pods, and some aircraft had three stores pylons on each wing, along with the wingtip rails.

An infrared track-&-search (IRST) sensor was fitted just in front of the cockpit along with a laser rangefinder, and the nose accommodated the "N-001" long-range radar system. In later production Su-27s, the tail stinger extension accommodated the tail radome for the "SPO-15 (L-006) Beryoza" radar homing and warning system (RHAWS), as well 32 three-shot chaff-flare dispensers. The stinger possibly also stored a jammer system.

The Su-27 was built mostly of light aluminum alloy, with some stainless steel and titanium. Flight controls were hydraulically operated, with some pneumatic backup systems. The nosewheel retracted forward, as did the main gear, rotating 90 degrees to lie flat in the wing roots. The pilot sat high with a good view in a Zvezda "K-36DM" zero-zero ejection seat. The ejection seat provided a "NAZ-8" survival pack, with rescue radio / beacon, rations, flares, medical supplies, and an inflatable raft.

The Su-27 was powered by twin Saturn-Lyulka AL-31F afterburning turbofans, with 12,515 kilograms (27,600 pounds) afterburning thrust each. The AL-31F was very reliable by Soviet engine standards, with a good time between overhaul of 1,000 hours, and the airframe allowed easy access to the engines.

   _____________________   _________________   _______________________
   spec                    metric              english
   _____________________   _________________   _______________________

   wingspan                14.7 meters         48 feet 3 inches
   length                  21.9 meters         72 feet
   height                  5.93 meters         19 feet 6 inches

   empty weight            16,380 kilograms    36,100 pounds
   max loaded weight       28,300 kilograms    62,400 pounds

   maximum speed           2,500 KPH           1,550 MPH / 1,350 KT
   service ceiling         18,000 meters       59,000 feet
   combat radius           1,500 kilometers    930 MI / 810 NMI
   _____________________   _________________   _______________________

* Su-27s began to perform mock intercepts of Western aircraft over the Barents Sea in early 1987, though at first they kept their distance. However, Norwegian F-16 pilots soon managed to get pictures of the type, and in September 1987 the crew of a Norwegian P-3 Orion ocean-patrol aircraft got a much closer view than they liked when an Su-27 clumsily clipped one of the P-3's propellers with its tail. Fortunately, both aircraft made it safely back home.

The Su-27 made its formal introduction to the West at the 1989 Paris Air Show, when Viktor Pugachev ran the aircraft through the now-famous "Cobra" maneuver, lifting the fighter to an angle of attack of over 90 degrees to its line of flight, causing abrupt deceleration until it nosed back down. The Cobra maneuver was apparently invented by another Sukhoi test pilot, Valerii Menitsky, as a flight-test exercise, but it became associated with Pugachev, it seems with his encouragement, and is also often called the "Pugachev maneuver" or "Pugachev Cobra". Few aviation experts believe that the Cobra maneuver has much combat utility, but it is undeniably a spectacular airshow trick.

It still shocked Western observers, since there were few or no Western aircraft that could perform the Cobra maneuver, and even though it may have been nothing more than a stunt, it demonstrated that the Su-27 was remarkably agile and very strongly built. However, observers noted that an Su-27 fully loaded for combat operations would not have anywhere near such capabilities, and is likely not all that capable as a close-in dogfighter, unsurprising for a big aircraft designed as a long-range interceptor.

The Su-27's agility is still impressive given its size, all the more so because the Su-27 is not a "dynamically unstable" design. Western designers have chosen to build maneuverable aircraft by designing them to be aerodynamically unstable, and then using advanced control systems to keep them in the air. Russian designers, preferring reliability and with less access to sophisticated avionics systems, opted for building a stable design and tweaking it for maximum maneuverability.

The Su-27 was, as mentioned, originally developed as a long-range "fighter interceptor" for the VVS and the Soviet air defense command (PVO), and was largely optimized for this role. Typical air-defense warload could be six "beyond visual range (BVR)" missiles and two or four short-range "dogfighting" missiles. While the Su-27's standard BVR missile, the "R-27" or "AA-10 Alamo" in its NATO codename, is regarded as inferior to the US AIM-120 AMRAAM, the standard dogfighting missile, the "Vympel R-73 / AA-11 Archer", is regarded one of the best in its class.

The R-73 has an "off-boresight" engagement capability, with the pilot cueing it to a target not directly in front of the aircraft with a helmet-mounted sight. The helmet-mounted sight can also be used to cue the IRST and laser rangefinder. While the US was developing AMRAAM at great expense and difficulty, the Soviets moved ahead with the R-73, and now the Americans are trying to catch up with the "AIM-9X Sidewinder" AAM.

The Su-27's electronics systems are less sophisticated than those of equivalent Western aircraft, and there are questions about their reliability, but the IRST has good tracking capability and the radar has excellent range, However, the radar does not have processing sophistication of Western counterparts. In the air-defense role, the Su-27 is designed to operate in conjunction with ground or air-based air-defense networks, a traditional Soviet practice, and the Su-27 has a datalink to allow it to perform intercepts "passively", without using its own radar.

Although the reliability of the Su-27's electronics may be uncertain, Russian partisans like to mock Western aircraft for their delicate mechanical nature and inability to operate off of rough airstrips. The rugged Su-27 was designed for such an environment and has no difficulty with it.

The large size of the Su-27 makes it useful as a strike aircraft, able to carry a wide range of munitions, but strike is a secondary mission for the basic Su-27. A reasonable judgement of the Su-27 would place it as superlative in its role as a fighter-interceptor, but probably not the equal of the F-15 as a multirole aircraft.

* By the way, the Su-27 has no formal name. Sukhoi says the aircraft is referred to as the "Azure Lighting", but it appears that it is generally called the "Crane", for its bent-necked appearance in flight. Some sources claim that Russian personnel occasionally even refer to it by its NATO codename, "Flanker".



* The Su-27 is a big and complicated aircraft that demands much of its pilots, and so during T10 and T10S development the Sukhoi OKB also worked on a two-seat operational trainer version. Due to the development difficulties discussed earlier, work on the two-seat version had to be set aside until the single-seat version was in production, and the first two-seat T10U prototype did not fly until March 1985, entering production and service as the Sukhoi "Su-27UB" a year or two later. While initial prototypes were built in Sukhoi OKB facilities in Moscow and Komsomolsk, full production was transferred to a state factory in Irkutsk.

The Su-27UB has a tandem seats under a single canopy, with the back seat stepped up above the front seat, providing the flight instructor in the back seat a good view of both the world in front of the aircraft and of what the trainee in the front seat is doing. Sukhoi engineers like to point out that the view from the rear seat is much superior to that from the rear of two-seat F-15s. This arrangement gives the Su-27UB an even more "crane-necked" appearance than the Su-27.

The second seat was accommodated by stretching the fuselage, and the vertical tailfins were increased in height slightly to compensate for the changed aerodynamics. The Su-27UB was designed to be fully combat capable. Addition of the second seat increased the weight of the aircraft by only about 1,120 kilograms (2,470 pounds) without reduction in fuel capacity, and aside from minor increases in runway requirement and comparably minor decreases in top speed, the Su-27UB's performance is very similar to that of the single-seat Su-27. Like the single-seat Su-27, early production Su-27UBs lack certain systems and features of late-production aircraft.

* The late-production single-seat Su-27 was used as the basis for the export variant, the "Su-27SK" (where "SK" stands for "Series Kommercial"). While the Su-27SK is externally all but identical to the Su-27, it has a downgraded system fit. A two-seat "Su-27UBK" was also built for the export market.

The Chinese were the first export customer for the Su-27, signing a contract in 1991 for 24 Su-27SKs and 2 Su-27UBKs, with initial deliveries in 1992. The Chinese bought another batch of exactly the same number and types of aircraft in 1995, and in 1996 the Chinese signed a license agreement to allow them to produce up to 200 Su-27s of their own. The license agreement apparently stipulates that they cannot export the type, which has the Chinese designation of "J-11".

In 1999, the Chinese ordered 40 "Su-30MKK" multirole combat aircraft, which feature a new radar and fire-control system. The Su-30 variants are discussed in more detail later. Initial delivery of a batch of ten took place in December 2000.

In the mid-1990s, Vietnam, not to be outdone by their ancient Chinese rival, also bought a number of Su-27s. Syria, Algeria, Iran, and Libya have expressed various levels of interest in obtaining the type as well. Of course, a number of Su-27s were "inherited" by some of the newly independent states, such as Belarus and Kazakhstan, created by the collapse of the USSR, but these were not export variants.

* The Soviet Navy had planned to acquire four fleet aircraft carriers, and so accordingly planned to build navalized versions of the MiG-29 and Su-27 for carrier operations.

Work on a navalized Su-27 actually went back almost to the very beginning of the design of the Su-27 family. T10S prototypes were modified to test features of navalized variants in an incremental fashion. The first test flights, from a dummy land-based carrier deck at Saki in the Crimea, featured aircraft fitted with with small canard wings for better low-speed approach, improved short takeoff performance, and enhanced combat maneuverability. Tests then went on to aircraft fitted with arresting gear, and then to tests of aircraft with carrier landing systems.

The carriers were to be fitted with "ski-jump" takeoff ramps, rather than catapults, and one of these navalized Su-27 prototypes made an initial takeoff from a land-based ski jump in August 1982. In operational practice, the aircraft was to take off a carrier deck by building up full thrust against a tilt-up blast deflector panel until the aircraft sheared restraints holding it down to the deck. The fighter would then accelerate up the deck and be tossed into the air with the ski-jump.

This unusual scheme was devised because the Soviets had no experience in building aircraft carrier catapults, and didn't want to delay introduction of the carriers while puzzling around with a new and demanding technology.

These modified prototypes led to specific prototypes for the navalized aircraft, designated "T10K". These aircraft had canards, an arresting hook, and carrier landing systems, as well as a retractable inflight refueling probe to allow the aircraft to take off with a reduced fuel load and top off in flight. However, they did not have the ruggedized landing gear required for carrier landings, and lacked folding wings. Pugachev flew the first T10K in August 1987, though that particular aircraft was lost in a mishap in 1988.

The production navalized "Su-27K" featured the required heavier landing gear and folding wings, with drooping outer ailerons and inner double-slotted flaps for low-speed carrier approaches. It began carrier trials on board the carrier TBILSI in November 1989, again with Pugachev at the controls, leading to introduction to formal carrier operations in September 1991.

A batch of 18 Su-27Ks were built in 1982 and 1983, though abandonment of plans for the four-carrier force in the aftermath of the collapse of the USSR meant that the need for building more Su-27Ks vanished. The KUZNETZOV, as the TBILISI had been renamed after the end of the Soviet Union, made a cruise in the Mediterranean in 1996, giving the Su-27K its first taste of ocean operations. NATO assigned the Su-27K the codename "Flanker-D", while the Sukhoi OKB calls the aircraft the "Su-33".



* The fact that the Sukhoi OKB refers to the Su-27K as the Su-33 reflects changes in Russian society since the end of the USSR. The old Communist bureaucrats disappeared, to be replaced by marketing officials, which not only seems like a questionable improvement but also leads one to wonder if they're not sometimes the same people.

At any rate, the Sukhoi OKB has pursued new variants of the Su-27 family and has given them a bewildering range of new designations as marketing ploys, made all the more confusing because their Russian military counterparts have insistently stayed with conventional designations. One Western observer commented on the Sukhoi OKB in 1995: "They produced more new designations than airframes this year."

Given the difficult economic and political environment of the new Russia, unsurprisingly many of these new variants have not gone farther than prototypes, or even just models and mockups. However, Sukhoi has been healthier than its competitors, apparently largely due to the political skills and influence of the current OKB Director General, Mikhail Simonov, who succeeded Pavel Sukhoi after his death in 1975.

* While the original Su-27 had good range, it still did not have enough range for certain air-defense tasks required by the PVO, and so prototypes were built of Su-27s featuring a retractable inflight refueling probe, similar to that used on the Su-27K. The probe was offset to the left side of the nose, and to accommodate it the IRST was offset to the right. One single-seat prototype was built and designated "Su-27P", and one twin-seat prototype was built and designated "Su-27PU".

The two-seat Su-27PU was felt to offer more promise, since long-range missions really require two crewmen, and so two improved Su-27PU prototypes were built with dual controls; long-range navigation avionics; and an updated N-001 radar, providing some air-to-ground attack capability and the ability to track and engage multiple aerial targets at one time. The first of these two prototypes flew at the end of December 1989.

Sukhoi offered an option to allow an Su-27PU to be used as a "fighter controller", sort of a mini-AWACS, with the back-seater using the radar and data links to control other fighters. However, the PVO wasn't buying, since they were in a difficult financial situation and preferred to stay with the proven MiG-31 for long-range interception. A few aircraft designated Su-27PUs have ended up in PVO service in the training role, though it appears the only advanced equipment they have are the inflight refueling probes.

The Sukhoi OKB did not give up on the Su-27PU, and began to market variations under the company designation "Su-30". An "Su-30K" ground attack variant and an "Su-30M" multirole variant were proposed, with an export variant of the Su-30M offered as the "Su-30MK". A few Su-27PUs and Su-27UBs were "dressed up" in various plausible or implausible Su-30 configurations for airshows and marketing demonstrations. A specific Su-30M prototype flew in April 1992.

Sukhoi's marketing blitz paid off. Although Russian forces did not buy the type, in 1996 the Indian Air Force (IAF) ordered 40 Su-30MKs, enhanced to IAF specifications and designated "Su-30MKI".

As all the features desired by the IAF weren't actually available at the time of the order, the contract arranged for initial delivery of aircraft not much more sophisticated than the Su-27UB, presumably to be used for operational familiarization, and then gradually scaled up in capability to full-specification Su-30MKIs with canards, thrust-vectoring engine exhausts, an advanced phased-array multimode radar, and other new gear.

In December 2000, the Russians signed an agreement with India giving Hindustan Aircraft LTD (HAL) the right to license-build up to 140 Su-30MKIs. Initial production will be from kits provided by the Russians, but HAL intends to eventually handle complete fabrication of the aircraft.

The deal includes the right to license-build thrust-vectoring "AL32FP" turbofan engines. The avionics kit for these aircraft will include French-built subsystems, such as flat-panel displays and a head-up display (HUD) built by Thales (previously Thomson-CSF), as well as Indian-built subsystems.

The deal, which also included 200 T-90 main battle tanks, was worth $3.3 billion USD, and was the biggest single arms agreement ever signed between Russia and India. Since only 18 of the 40 Su-30MKIs ordered in 1996 had been delivered when the deal was signed, it is unclear if the remaining 22 aircraft in the old order are part of the new license contract.


[5] ADVANCED SU-27M (SU-35, SU-37)

* Many of the sophisticated features of the Su-30MKI were to be derived from another advanced Su-27 variant, the multirole "Su-27M", designed by a team under Nikolai Nikitin of the Sukhoi OKB beginning in the early 1980s. The idea was to build a multirole fighter that could excel as an interceptor, an air-superiority fighter, and a strike aircraft.

This was demanding, particularly because in many cases aircraft designed for multiple roles aren't necessarily excellent at any one of them. The Su-27M needed to carry avionics for air combat, strike navigation, and guidance of laser or TV guided smart munitions. It was also to be fitted with canards, and "wet" tailfins for additional fuel. This meant an increase in empty weight and a corresponding degradation in performance. The Sukhoi OKB felt the weight increase could be dealt with though improved "AL-31FM" or "AL-35" engines, and through reductions in weight using composite materials and lithium-aluminum alloys.

The Su-27M has proven to be not so much a particular variant of Su-27 as a series of increasingly refined prototypes. The first in this series flew in June 1988, and apparently was little different from a standard Su-27 except for addition of a refueling probe derived from the Su-27P, plus a new "glass cockpit". It was followed by more prototypes, adding features such as twin-wheel nose gear, and a new wing with eight stores pylons.

In 1992, one of these Su-27Ms was publicly flown at the Farnborough Air Show in the UK, and OKB chief Mikhail Simonov claimed it would be production by 1995. Apparently, other Sukhoi OKB officials present at this announcement went pale, and in fact the type has yet to enter production.

One of the problems is that, given the chaotic state of the post-Soviet industrial system, developing the avionics for an operational Su-27M has been extremely troublesome. Originally, the aircraft was to be fitted with an advanced NIIP "N-011" multimode radar, but this development program has been a moving target. The latest implementation of the N-011 has been stated to have a range of up to 160 kilometers (100 miles), the capability to track 20 targets at once, and engage six of those targets at once.

NIIP's rival Phazatron has responded with the "Zhuk-27" radar, or the similar "Zhuk-PH" with a phased-array antenna. The Zhuk-PH is stated to have a slightly longer range and wider scan angle than the N-011, the capability to track 24 targets at once, and engage eight of them simultaneously. NIIP, not to be outdone, has proposed a new radar of their own that not only has multimode capability, but can track aerial and ground targets at the same time.

One of the other incremental improvements of the Su-27M was a new and bigger tail stinger, intended to house an "N-012" rearward-facing radar, with a range of up to 50 kilometers (31 miles). The N-012 would cue rearward-firing AAMs, a concept which has been flight-tested by the Sukhoi OKB. The Su-27M is also to have a comprehensive EW suite for offense and defense, but the status of this effort is uncertain.

To no great surprise, Sukhoi marketing redesignated the Su-27M to "Su-35", but equally to no surprise, the Russian Air Force still calls it an Su-27M. In April 1996, the Sukhoi OKB flew yet another advanced prototype, calling it an "Su-37", though it is likely that to the VVS it's just another Su-27M.

However, the Su-37 does have a major new feature with its "AL-37FU" engines. These new engines offer more power than the traditional AL-31 engines, with 14,500 kilograms (32,000 pounds) afterburning thrust each, but more significantly they are fitted with thrust-vectoring exhaust nozzles that move in the vertical plane. The AL-37FU is said to be interchangeable with the older AL-31, and interestingly the nozzles are actuated by pressurized fuel, not hydraulic fluid, possibly as a means of providing some fuel preheat.

The Su-37 also features an advanced glass cockpit, with three multifunction displays, a sidestick controller, and a nonmoving, pressure-sensitive throttle. The Su-37 flew at Farnborough in September 1996 and performed maneuvers that dazzled the crowd. However, the cash-poor Russian military has yet to buy production quantities of any such advanced Su-27 variant.


[6] STRIKE SU-27IB (SU-34, SU-32FN)

* One of the most unusual Su-27 derivatives is the "Su-27IB", a dedicated strike variant with a completely redesigned front fuselage that provides side-by-side seating. The first prototype flew in April 1990, but curiously it was kept a secret for several years.

In fact, rather than being over-promoted by Sukhoi OKB officials as they had learned in the New Russia, it was hidden by a misinformation campaign much like that of the old USSR, with Mikhail Simonov claiming it was an operational trainer for carrier landing. This fable was reinforced by a picture of the Su-27IB coming in for a landing on the KUZNETZOV, though sharp-eyed observers noted that the aircraft did not have an arresting hook extended and was likely only making a "touch and go" for the cameraman.

The truth eventually came out, with the Su-27IB designation revealing its true nature, since the "IB" stood for "Istrebitel Bomardirvoschik / Fighter Bomber". It was intended to replace the Su-24 "Fencer". Sukhoi OKB officials refer to the type as the "Su-34" or "Su-32FN", but VVS officers simply call it the Su-27IB. The Su-32FN has been advertised as a variant optimized for maritime strike, but that may simply be Sukhoi OKB marketing hype.

The initial prototype was an SU-27UB mated with the new nose for aerodynamic validation, with a full-specification prototype flying in 1993. The new side-by-side cockpit is said to be roomy and comfortable, and even has a toilet and a galley for long missions, though it is also said that its visibility is unsurprisingly inferior to that of fighter Su-27 variants.

The cockpit is protected from ground fire by a titanium "bathtub", and titanium armor is also used to protect fuel tanks. The total weight of added armor is estimated at about 1.5 tonnes (1.65 tons). The undercarriage has been changed completely to permit higher takeoff weight, with the main gear having tandem wheels on longer struts, and a two-wheel nosegear that retracts backwards. The crew gets into the aircraft through an access ladder in the nosewheel well. The Su-27IB has fixed-geometry inlets, meaning it is not capable of high supersonic speeds, but that was apparently not regarded as important for the strike role. The dorsal airbrake was deleted.

The SU-27IB is said to have a warload capacity of up to 5,440 kilograms (12,000 pounds). It features canard foreplanes; a retractable inflight refueling probe; a glass cockpit; a digital fly-by-wire control system; and a phased-array radar in the broad "platypus bill" nose, the radar providing terrain-following capabilities as well as a number of other combat modes. The SU-27IB also has new tail stinger much like that of the Su-27M, probably containing rearward-facing radar, and is still capable of air-to-air combat.

The VVS ordered 12 Su-27IBs for evaluation in 1996, but the delivery status of these aircraft is unclear. The appearance of the Su-27IB is clearly different from that of any other Su-27 variant, even to the untrained eye. Some find its appearance exotic and science-fictional, others find it hideously ugly, but all agree that it has a very unusual appearance.



* The Su-27 remains the first-line fighter of the VVS, serving in roughly a dozen air regiments. The PVO was disbanded in the 1990s and its units absorbed into the VVS. The VVS is proud of the Su-27, and brightly colored "Cranes" are internationally prominent in Russian aerobatic demonstration teams such as the Russian Knights. In the current financial climate, however, it may be difficult for the VVS to keep them all flying, much less update them or order new aircraft.

The Sukhoi OKB has been able to maintain forward momentum and even offer technical improvements through an aggressive program of foreign sales. The Indian Air Force deal was a particular coup, and the IAF's possession of such powerful long-range fighters has been a worry to other nations in the region, such as Pakistan and Australia.

The actual combat effectiveness of the Su-27 is hotly debated. In the absence of much in the way of actual combat experience for the type, at least in terms of confronting Western combat aircraft that could be presume to be its peers, such arguments are basically academic and tedious, with both sides simply gathering up facts to justify their prejudices and making almost no pretense of objectivity. Oddly enough, in some cases Western analysts have taken an optimistic view of the Su-27's capabilities, in order to support new Western aircraft programs to counter the threat.

The comparison game is also played with other Russian aircraft. Many analysts believe that advanced versions of the lower-cost MiG-29 are a better value for the Russian state at this time, particularly in light of its lower cost, and that the political influence of the Sukhoi OKB has led the country to adopt a the wrong solution.

A well-conducted and thorough comparative flight evaluation of the Su-27 versus, say, the F-15 and F-16 would provide much more substantial information on the strengths and weaknesses of the Sukhoi fighter, but it appears this has not been done, or if it's been done nobody's talking. However, one thing is clear: Su-27 pilots love the thing.

* Despite the difficult environment, the Sukhoi OKB seems to be doing well, with a net profit for 1999 of the equivalent of $7.58 million US, nine times better than 1998. Average monthly salaries in the Sukhoi OKB are the equivalent of $160, a pittance compared to aviation workers in the West, but better than any other Russian firm, and the Sukhoi OKB is meeting its payrolls.

While this may sound like evidence that Russian firms are starting to find their way, however unsteadily, to their feet in a new economic environment, it is still unsettling that even the Sukhoi OKB admits that only 2% of their revenue was provided by Russian defense contracts, with the bulk of their money coming from foreign purchases.



* The Sukhoi OKB has had plenty of ideas for next-generation fighter aircraft, for example a single-jet lightweight with the general configuration of the Su-27M but about half the weight, and in the class of the US F-16 fighter. Sukhoi has displayed a model of this concept, designated "S-54", at international airshows in recent years. More significantly, the organization has developed a new experimental prototype aircraft, the forward-swept-wing Sukhoi "S-37 Berkut (Golden Eagle)".

In 1983, the Sukhoi OKB began work on a heavy fighter designated the "S-32", with a forward swept wing, as a parallel effort to work being done by the MiG OKB for next-generation fighters for the 1990s. The Soviet government decided to emphasize the MiG efforts, but allowed the S-32 work to continue on an experimental basis.

With the collapse of the USSR and the following economic woes, work on the S-32 had to be suspended, but as the Sukhoi OKB began to make money from foreign sales, Mikhail Simonov decided to continue the project with company funds. Due to security concerns, the S-32 became the "S-37". The type made its first flight in September 1997, with Igor Votintsev at the controls. The S-37 is now in flight tests, and the Sukhoi OKB is apparently receiving some state funding for the effort.

While details of the S-37 remain classified, it has flown in public demonstrations. It is of size and general configuration similar to that of late-model Su-27 variants, though of course noticeably different with its forward-swept wings. Although forward-swept wings have traditionally had problems due to excessive structural loads, the S-37's wings use advanced composite materials to give them the necessary strength.

The S-37 has a wingspan of 16.7 meters (54.7 feet), a length of 23.8 meters (78 feet), and a normal takeoff weight of (56,600 pounds). It is powered by two Aviadvigatel "D-30FG" turbofans, similar to those used in the MiG-31M, with 25,700 kilograms (34,200 pounds) takeoff thrust each. It is an inherently unstable aircraft that is kept in controlled flight using a fly-by-wire system, something of a tacit admission that the dynamically unstable approach has its virtues. Interestingly, the Berkut is so large that its wings fold to allow it to fit into Russian hangars.

* In the spring of 2001, Sukhoi officials announced a collaborative program involving Sukhoi; all of Russia's aviation research institutes; and many of Russia's aviation industries to develop an operational next-generation fighter, under the "Future Air Complex for Frontal Air Forces (Perspektivnyi Aviatsionnyi Kompleks Frontovoi Aviatsyi / PAK-FA)" program. A collaboration between the MiG and Yakovlev concerns also developed a proposal.

In late April 2002, the Russian government announced that the Sukhoi-led group would build the PAK-FA, though the MiG-led group would have some participation in the program. The PAK-FA will be somewhere between the size of the MiG-29 and the much larger Su-27. It is expected to compete with the American F-35 Joint Strike Fighter (JSF) in export sales, and eventually probably in air combat.

The schedule for the PAK-FA is very ambitious, with a draft design to be fixed before the end of 2002, initial flight of a prototype in 2006, and introduction to service in 2010.

Simonov stated that the new Sukhoi fighter will be a multirole aircraft, and would be able to operate from aircraft carriers as well. Sukhoi officials insist that the S-37 is not a prototype for the new operational fighter. They emphasize that the S-37 is strictly an experimental platform, but add that its technology will be leveraged into the new design.

Sukhoi is also engaged in discussions with India on a partnership to help develop the PAK-FA. The Sukhoi group is providing India with data on the S-37 and obtaining India's requirements for the new aircraft.



* I find the games played by Sukhoi OKB officials in redesignating Su-27 variants amusing, as I spent about 14 years working as a technical support person in a marketing organization. The marketing people occasionally made public statements that were so false and ignorant that I wanted to go over and shoot them to the Moon.

I spent three years in the US Army before that, and though I did not learn to admire the military mind, one of its good qualities is a low tolerance for this kind of nonsense. I suspect that Sukhoi OKB officials who slip up and refer to an "Su-35" in front of senior VVS officers feel lucky if all they get in response is a blank stare.

I'm not really a great Su-27 fan myself. It's a little on the big side to be particularly attractive as a fighter, and I much prefer the MiG-29. However, it is an impressive aircraft and Russia's premier fighter.

* I have somewhat glossed over the various prototype and minor variant developments of the Su-27 in this document in order to clarify the evolution and actual use of the type. Those interested in more detail can consult the following sources:

* Revision history:

   v1.0   / 01 aug 00 / gvg
   v1.0.1 / 01 feb 02 / gvg / Minor corrections.
   v1.0.2 / 01 jun 02 / gvg / Added comments about Sukhoi win of PAK-FA.