VLADIMIR KARNOZOV / MOSCOW
Despite having first flown 25 years ago, Sukhoi's proliferating Flanker family could continue in production for at least 15 years
Russia's Mikoyan and Sukhoi fighter design bureaux are battling to lead the development of the fifth-generation LFI lightweight frontline fighter. They face a common challenge: to come up with a design that will be economically and technically superior to the newest derivatives of the Su-27 Flanker. Some voices in the industry question the need for an all-new fighter, proposing instead to continue the incremental improvement of the Flanker as the platform for new and upgraded avionics and precision-guided munitions. The revised LFI specification, prepared by the Russian air force last year, seeks a medium-weight multirole aircraft sized to closely match the RSK MiG-29 Fulcrum - ruling out a derivative of the larger Flanker.
The specification requires the LFI to fly in 2006 and enter production four years later. Even if development goes to plan, therefore, the Su-27 family will still be the best Russian fighter available for some time to come.
Russian arms export agency Rosoboronexport says Sukhoi fighters account for 14% of the fighter market with orders worth $10 billion. Rosoboronexport intends to sell 450-500 Su-27-family fighters over the next 10 years. Current competitions include, in chronological order, Malaysia (Su-30MKM), Brazil (Su-35) and Singapore (Su-30/35).
Although the Su-27 will be available for the next 10-15 years, the design emerged in 1971 as a counter to the US Boeing F15 - a blended wing-fuselage, aerodynamically unstable twinjet with artificial stability and a hybrid analogue/digital fly-by-wire system. The T-10-1 technology demonstrator flew in May 1977. In 1981, Sukhoi flew the completely redesigned T-10S, which entered service in 1984 as the Su-27.
Limited production
The Komsomolsk-na-Amur Aircraft Production Organisation (KnAAPO) launched production in 1982, with the IAPO factory in Irkutsk joining in 1986. NAPO in Novosibirsk was to build the Su-27IB (also referred to as the Su-32/34) fighter-bomber, but Russia's long-running economic woes have limited production to nine aircraft. The Su-27IB flight-test programme has stuttered on since 1990 and is not due to be finished until 2004-05, with deliveries to the Russian air force "after 2005".
All single-seat aircraft - Su-27 and export Su-27SK (China, Ethiopia, Syria, Vietnam) air-defence fighters and the Su-27K (Su-33) for aircraft carrier operations - are KnAAPO-built. IAPO manufactures the twin-seat Su-27UB and Su-2UBK (for export) operational trainers as well as the Su-30 two-seat interceptor and its export derivative, the Su-30K. Production of these specialised models is nearing an end, following the introduction of the Su-30MK multirole platform developed in response to export customers' criticism of the Flanker's limited ground-attack capabilities. The criticisms mainly centred on the primitive targeting system and low payload/range performance. In large-scale production are the Su-30MKK for China and the Su-30MKI for India at KnAAPO and IAPO, respectively.
There are numerous other derivatives, experimental aircraft, development prototypes and initial production fighters. The Su-27SMK, Su-30KI and Su-37 are among those developed for overseas customers but never ordered. There are several other models with undetermined status - developed and flown, but without firm orders. KnAAPO has prepared tooling for the Su-35 single-seat multirole fighter, its tandem twin-seat variant the Su-35UB, and the Su-27KUB twin-seat side-by-side combat trainer for aircraft carrier operations.
IAPO is funding development of theSu-30KN and Su-27UBM, as well as mid-life upgrades for Russian air force Su-30-Ks and Su-27UB/UBKs, with the focus on adding precision weapons. Last year, the air force awarded IAPO a contract to upgrade 30 aircraft in 2002-03. The upgrade is generally applicable to all single-seat Su-27s - Russia's 400 aircraft and those operated by Belarus (23 aircraft), Kazakhstan (four), Ukraine (67) and Uzbekistan (30).
The plethora of variants stems from Sukhoi's policy of offering potential customers tailor-made aircraft. The policy has not always been successful, but it did succeed in securing multi-billion dollar orders in China and India.
Sukhoi general director Mikhail Pogosyan says: "Development [of the Su-27] never stopped, and it keeps moving. In the past 15 years we made a huge effort on developing the basic platform and we have created a whole family of aircraft with improved performance, and upgraded avionics and weapons, contracting a long chain of co-developers and systems manufacturers. The sustained development effort enables us to master new technologies in aircraft design and manufacturing."
Restructuring
In October, Russian president Vladimir Putin, unhappy with the "unhealthy competition" between IAPO and KnAAPO for exports, ordered the formation of the Sukhoi Aviation Holding Company, which should be completed next year. KnAAPO and NAPO are being turned into joint-stock companies that will subsequently be transferred to the Sukhoi holding company. State shareholdings in OKB Sukhoi (the design bureau), Beriev and IAPO have already been handed over. Apart from obvious economic and marketing benefits, the union will create a global support system. Pogosyan says: "As soon as we get the licence [to sell spare parts to exported aircraft], we will start formation of regional support centres around the world. The goal is to have the quality of after-sales support corresponding to the latest international standards. We already have customer support departments in the design house and production factories; the new task is to unite their efforts to give customers aunitary system for after-sales support of Sukhoi aircraft."
Basic Su-27 radar options are variants of the Tikhomirov NIIP N-001 pulse-Doppler radar with a mechanically scanned antenna. The Su-27 can attack only one air-to-air target at a time, while the Su-30MKK's can handle two targets simultaneously, attacking them with medium-range, radar-guided Vympel RVV-AE (AA-12 Adder) air-to-air missiles. A newer version has a ground-mapping mode and can guide the Zvezda Kh-31A anti-ship missile. Under test is a unit with high-resolution mapping, capable of targeting radar-guided PGMs.
The Su-30KN Stage I has the originalN-001 with the "strap-on" Oko bypass channel and Baget-55 processor. It has additional working modes, including 20-50m (65-165ft) resolution ground mapping and moving-target indicator modes. The Stage II can track and shoot at two targets simultaneously. The Stage III has a Peropassive phased-array antenna and a higher power transmitter, offering the benefits of electronic scanning and digital processing. Stage III aircraft, designed as command posts, have three 150 x 200mm (6 x 8in) liquid-crystal displays in the pilot's cockpit while the rear-seat operator has four. A secure datalink allows a Su-30KN Stage III to illuminate a target for a long-range missile launched from another aircraft.
The newest radar is the NIIP N-011M Bars with a passive phased-array antenna. Its manufacturer claims it is the most advanced multimode fighter radar available. "We can count the number of blades in the engine of the aircraft in sight and by that determine its type," NIIP says. It is claimed the Bars can build a "portrait" of five targets in 1s. This mode has been tested on the Su-30MK/Su-35. The Bars can track several targets while continuing to scan for more and simultaneously track airborne and ground targets. The export variant can track over 10 targets and shoot at four, but these numbers will grow with new software releases, the company says, adding that, in flight-testing, the radar detected an air target at 330km (180nm). Improved Bars will have extended range through use of an enhanced signal amplifier and increased power transmitter.
Phazotron-NIIR's Zhuk-MS radar is being tested on the Su-27KUB and Su-30MKK Series III. Based on the RSK MiG-29MRCA's Zhuk-M, it has a larger mechanically scanned antenna providing a detection range of 150-180km against a fighter and over 300km against a warship. A 3-6m resolution ground-mapping mode is being tested, says Phazotron-NIIR general director Anatoly Kanashenkov. The company is developing an active-array antenna and intends to test it on a development radar in mid-2003.
The Su-27IB was to have a Leninets sensor suite, integrating a forward-looking passive electronically scanned radar, with provision for an active array, and an active rear-looking unit. Development ran into technical and financial difficulties, so NIIP is offering the compact Osa electronically scanned radar for tail protection and precision-weapon targeting.
New designs
Sukhoi's newest designs are set to be 100% digital. Organisations in the holding company - OKB Sukhoi, KnAAPO, IAPO, Beriev, NAPO, and NITsASK, the scientific research centre for automated design systems - are thousands of kilometres apart and so built a corporate network to link them. With the LFI in mind, they have pursued continuous acquisition and lifecycle support, and computer aided design/manufacturing (CAD/CAM) technologies. KnAAPO and OKB Sukhoi are Russia's largest users of the US Unigraphics, Nastran and Autodesk packages.
The Su-30MKK has a redesigned airframe developed using three-dimensional modelling and CAD/CAM. It was strengthened to allow a 38,000kg (83,700lb) maximum take-off weight. The fighter can carry an 8,000kg weapon load on 12 stations and 10,000kg of internal fuel. The aircraft has two 150 x 200mm LCDs in each cockpit. The Su-27's ground-attack weapons capability - limited to unguided rockets - has been replaced by an integrated system allowing the use of precision munitions.
The electronic warfare suite has been revised, receiving a sensitive radar warning/intelligence-gathering unit with an enlarged library of potential threats as well as the potential for expansion.
The Su-30MKK has an improved N-001 with additional data processors and an air-to-ground mode. Targeting is provided for a host of Russian air-to-surface missiles and guided bombs.
The Su-35 "Super Flanker" flew in 1988, as the Su-27M, and is marketed as theSu-27/30's successor. A higher degree of aerodynamic instability (the Su-27 is close to neutral), a canard-wing-tailplane configuration and thrust-vectoring requires a fully digital quadruplex flight control system (FCS). "We even made a corkscrew spin a controllable manoeuvre - the pilot can leave it at any moment by a single motion of the stick that engages thrust-vectoring and aerodynamic surfaces," says Sukhoi general designer Mikhail Simonov. "The greatest challenge was to make a highly sophisticated, naturally unstable supersonic jet's handling qualities resemble those of the Polikarpov Po-2 biplane.
"In fact, we cheat the pilot using computer technologies. The Super Flanker's flight control system automatically observes limitations on the angle of attack, pitch, speed and so on, reducing workload on the pilot and letting him focus on the combat task."
The Su-35's take-off weight is boosted to 38,800kg, the weapon load to 8,500kg and the internal fuel capacity to 10,250kg. Airframe life is 6,000h. From 1992 to 95, KnAAPO made 12 single-seat prototypes, followed last year by a Su-35UB twin-seater.
The N-011M Bars radar is standard, while the core avionics suite and systems are from the Su-30MKK, but software is further improved to enable a single pilot to employ the same weapons that can be used by the Su-30MKK's two crew.
Chief designer Sergei Korotkov believes that the Su-35's competitiveness lies not so much with the avionics and "super manoeuvrability", but the ability to carry a heavy weapons load over long ranges using only internal fuel - all at a $35-40 million sticker price.
"Competitors fall short when it comes to payload/range, yet some try giving range with external tanks and still claim that all munitions are on board. External tanks produce high levels of drag and sit on pylons that otherwise would be occupied by weapons."
The Su-30MKI is the best-selling export Flanker, with an orderbook exceeding $5 billion. IAPO is to deliver 50 airframes this year and next, while India's Hindustan Aeronautics will build 170 under licence in 2003-17. Over $300 million has been invested in research and development since 1996 and the Su-30MKI has aerodynamic performance, thrust-vectoring engines, an FCS and radar similar to those on the Su-35.
Avionics
Unlike the Su-35, however, it has extensive non-Russian avionics. The tandem cockpits have Thales multifunction colour displays (MFDs) and Elop head-up displays (HUDs). The Rif navigation/weapons system has been integrated by Ramenskoye RPKB, but includes French, Indian, Israeli and Russian items.
The Su-30MKI also has an UOMZ OLS-30 electro-optical sensor with a 90km detection range, 12 weapons stations able to carry targeting, reconnaissance and electronic warfare pods, and the gamut of Russian air-to-air and air-to-surface weapons. At a take-off weight of 38,800kg, the aircraft has a 3,000km range on internal fuel and 5,200km with one in-flight refuelling, says Sukhoi.
IAPO chairman Aleksei Fiodorov says the Su-30MKI's aerodynamics and Lyulka Saturn AL-31F turbofan engines will stay competitive without major upgrades for 10-12 years. "Launching an all-new fighter with new engines and airframe into full-scale development is premature.
"Instead, financial resources available should be concentrated on weaponry, avionics and materials. The Su-30MK can bridge the gap, incrementally developing from a 'fourth-plus' to 'fourth-plus-plus' generation fighter, with more 'pluses' gradually bringing it closer and closer to the fifth generation."
Source: Flight International
