Sukhoi Su-27M / Su-35
The Su-27M (factory designation T-10M) was conceived as a new upgraded variant of the Su-27 'Flanker' incorporating a true air-to-surface capability. Although the capability to carry air-to-surface weapons had been added to the baseline Su-27S, it was limited to 'dumb' bombs and unguided rockets. The Su-27's fire control system lacked a dedicated ground target acquisition and identification capability. Although Su-27M remained the Russian military designation, the Su-27M later received the Su-35 designation to enter the global fighter market. Having failed to attract any orders for the Su-35 between 1992 and 2002, Sukhoi started a new development program for the modernization of the single-seat Su-27 in 2002 under the bureau/factory designation of T-10BM (Bolshaya Modernizatsiya - Big Modernization). This latest Flanker derivative also aimed at the export market retained the Su-35 designation of its predecessor, despite significant differences between the two Flanker derivatives.
The Su-27M was equipped with the upgraded RLSU-27 radar system. The system was composed of the new forward-looking N011 radar with slotted-array and the smaller N012 rear-looking radar, the latter is located in the central tailboom. Compared to the RLPK-27 system with the N001 radar of the basic Su-27 variants, the RLSU-27 system offered extended target acquisition range, air-to-surface stand-off attack capability, simultaneous tracking of more targets, surveillance and tracking of targets in the rear hemisphere and improved counter ECM. The new radar system also provided terrain-mapping, enabling nap-of-the-eartch (NOE) flying and obstacle avoidance.
Later it was concluded that the slotted-array would be outdated soon, and a phased array variant of the N011 radar, designated N011M, was fitted to the Su-27M. The phased array enabled a greater radar range, wider zones of tracking and engagement, increase in number of simultaneously tracked and engaged targets, and the employment of more advanced weapons.
In addition to the radar, the Su-27M featured other advancements in its avionics suite compared to the Su-27. New components were the electro-optical sighting/navigation system, communications suite, instrument guidance equipment, new FBW system, IFF and digital computer. The aircraft was equipped with an advanced self-defence suite consisting of new RWR systems, Sorbtsiya ECM pods, and APP-50 chaff/flare dispenser.
The instrument panel layout was changed to accomodate three high-res multifuction monochrome CRT displays and an improved HUD, reducing the number of electro-mechanical instruments. The Su-35 was also offered with multifunction colour LCD displays. The IRST sensor was moved to the right off the line of symmetry to improve visibility from the cockpit. The ejection seat was elevated and declined at 30 degrees to enable the pilot to better withstand high G manoeuvering. The pilot would wear a helmet with the Shchel-3UM helmet-mounted target designator.
The Su-27M airframe incorporated a new nose section, new central tailboom, canards, and uprated AL-31FM engines. The wings panels were fitted with larger fuel cells and the enlarged fins have internal fuel cells as well increasing the aircraft's combat radius. Furthermore the Su-27M was fitted with a retractable in-flight refueling probe and the provision to carry two 2,000-litre underwing drop tanks to further extend its range.
The aircraft's structure and undercarriage was strengthened to cope with the increased weight of the aircraft caused by the new equipment. The single nose wheel was replaced by two smaller wheels.
The new systems enabled the Su-27M to be capable of using modern air launched weapons. The most important addition for the air-to-air role was the medium-range active radar homing R-77 (export designation is RVV-AE) air-to-air missile, the Russian equivalent of the AIM-120 AMRAAM. Up to twelve of these missiles could be carried or ten when equipped with wingtip ECM pods. The Su-27M retained the capability to be armed with the older R-27 semi-active radar, R-27E IR homing medium-range missiles as well as the short-range R-60 and R-73 IR homing missiles. All of which have since been developed into more effective versions.
These new systems and weapons capabilities made the Flanker a true multi-role fighter. Following the collapse of the Soviet Union, the Su-27M development slowed down and prospects of any significant production for the Russian air force soon vanished. Owing to its true multi-role capability, large action radius and reasonable price tag, the Su-27M was considered a good candidate for export. The Su-27M designated Su-35 was first shown at Farnborough international air show in 1993. Early attempts included the Su-35 based Su-37MR, which was marketed to the United Arab Emirates (UAE)). After the initial series production of three Su-27Ms had been completed for state trials, the Komsomolsk-on-Amur aircraft manufacturing association (KnAAPO) suspended production and refocused on meeting the requirements of possible export customers. Among the customization options was the possibility to equip the Su-35 with AL-31FP TVC engines, which were developed following the successful Su-37 trials with the first generation of AL-31FU TVC engines. Other improvements for the export Su-35 also included an open architecture avionics suite incorporating the latest digital computers and display systems.
Another step towards meeting future customer requirements was to develop a twin-seat combat trainer variant of the Su-35. Sukhoi and KnAAPO developed the Su-35UB. The first Su-35UB prototype (bort number 801) built by KnAAPO made its first flight on August 7, 2000. It was first shown at the MAKS 2003 air show and subsequently served as a technology demonstrator and test aircraft for various avionics, including the Zhuk-MSE radar.
Despite efforts by Sukhoi and KnAAPO to market the Su-35, it did not receive any orders. The Su-35 had been considered by a number of nations for their next generation fighter program. These include South Korea, Singapore, Australia and Brazil. Apart from Brazil, the Su-35 failed to get shortlisted by these countries.
Brazil however was forced to postpone the decision, but had shortlisted the Su-35 together with the Mirage 2000BR and the Saab Gripen initially. Sukhoi/KnAAPO introduced the designation Su-35BR for the customized Su-35s that could be developed for Brazil. Before completition of the second round the Brazilian F-X program was cancelled.
Another South American candidate for the Su-35 emerged in the form of Venezuela soon after. The country was effectively forced to consider Russian fighters to replace its F-16 fleet, following the US arms embargo that was imposed on it in May 2006. The Su-35 was one of the options considered, however the multi-role Su-30MK variant had matured over the years incorporating some of the improvements of the Su-27M. More importantly, the Su-30MKK and Su-30MKK2 had entered full production at KnAAPO for China. The FAV quickly opted for the Su-30MK2.
In total 17 Su-27M aircraft were built by Sukhoi and KnAAPO; five prototypes converted from Su-27s, two static test airframes, six pre-production test aircraft, three production aircraft, and one Su-35UB prototype. Although the Su-35 (Su-27M) had no success on the global fighter market, the Su-27M line greatly contributed to the development of the Flanker family, both in terms of aerodynamics and avionics. The Su-27M saw the introduction of canards and 3D fly-by-wire control for enhanced manoeuvrability. The final two preproduction aircraft T10M-11 and T10M-12 (bort numbers 711 and 712) tested the N011M phased-array radar. Aircraft '711' went on to become the Su-37 and was soon after converted to thrust vector control (TVC) demonstrator, fitted with AL-31FU and modified FBW system.
All of the aforementioned innovations were subsequently further developed to be fitted to Irkut's Su-30MKI for India, and subsequently the Malaysian Su-30MKM and Algerian Su-30MKA. KnAAPO's Su-30MKK and Su-30MK2 versions inherited the enlarged tailfins providing additional fuel capacity of the Su-27M.
Although the Russian Air Force never ordered more Su-27Ms to enter production for operational service, the handful of early Su-27M types continue to serve the air force. Five of the preproduction and production aircraft have been assigned to the Russian Knights display team, since the state trials of the type were suspended in the mid 1990s.
Su-27M '710' (T10M-10) continued to serve the company as a flying testbed in 2004-2006, flight testing the advanced AL-31F derivative by NPO Saturn, dubbed 117S (AL-41F), the new turbofan will power the next Su-27 derivative, which will also carry the Su-35 designation.
Sukhoi realized by 2002 that the original Su-35 (Su-27M) would no longer be able to compete with comtemporary and future foreign fighters. Furthermore, the Sukhoi-owned KnAAPO plant had been struggling to compete with its Su-30MK2 against the more advanced Su-30MKI derivatives of the Irkut Corporation, its rival Flanker producer only partially owned by Sukhoi. Sukhoi started development of a new 'intermediate fighter' to fill the gap between its "fourth generation" Su-30MK and the upcoming "fifth generation" fighter in development under the PAK-FA (Perspektivnyi Aviatsionnyi Kompleks Frontovoi Aviatsii - Future Air System for Tactical Aviation) program, while offering a KnAAPO alternative to Irkut's Su-30MKI line. Contrary to earlier reports, the resulting "4++ generation fighter" has materialized as a new Su-27 derivative as opposed to upgrade of the Su-27M. Re-using the Su-35 sans suffix designation, the Su-27 Bolshaya Modernizatsiya ('big modernization', factory designation T-10BM) differs significantly from the Su-27M, having been redesigned from the basic Su-27 configuration incorporating the improvements developed for the Su-27SM2 upgrade program.
The designation Su-35 had already been used from 1992 onwards to market the company's modernized Su-27M "Super Flanker" (bureau designation T-10M). Developed in the late 1980s for the Soviet Air Force, the Su-27M incorporated a modified aerodynamic configuration, uprated engine, and upgraded avionics. Sukhoi realized by 2002 that it would no longer be able to compete with comtemporary and future foreign fighters. The single-seat Flanker needed to be drastically upgraded, including a major redesign of its airframe. Furthermore, the Sukhoi-owned KnAAPO plant had been struggling to compete with its Su-30MK2 against the more advanced Su-30MKI derivatives of the Irkut Corporation, its rival Flanker producer which is only partially owned by Sukhoi. Sukhoi started development of a new 'intermediate fighter' to fill the gap between its "fourth generation" Su-30MK and its upcoming "fifth generation" fighter in development under the PAK-FA (Perspektivnyi Aviatsionnyi Kompleks Frontovoi Aviatsii - Future Air System for Tactical Aviation) program, Sukhoi developed a new "4++ generation" Su-27 derivative, internally known as T-10BM. The Su-27 Bolshaya Modernizatsiya ('big modernization') utilizes a redesigned airframes based on the standard Su-27 and is fitted with the latest Russian avionics, advanced weapons and new engines. Re-using the Su-35 sans suffix designation, it is primarily aimed at the export market, but Sukhoi also hopes to produce localized versions for the Russian Air Force.
Unlike the Su-27M and Su-30MKI, the new Su-35 features the same aerodynamic configuration as the basic Su-27, but with larger wings and engine intakes. The Su-35 is not fitted with canards. The flight performance and manoeuvrability will instead be improved by the advanced KSU-35 fly-by-wire system. It also lacks the larger vertical tails of the Su-27M. Internal fuel capacity has been increased by redesigning the airframe internal volumes. The Su-35 can carry 11,500kg of fuel, which can be increased to 14,300 kg using two underwing drop tanks. Like previous Su-27 derivatives, it has also been fitted with a retractable refueling probe. The new Su-35 lacks the Su-27's large upper air brake owing to advanced rudder control by the KSU-35 system.
Perhaps the most significant improvement is the extensive use of titanium alloys, which increases the aircraft's service life from 4,000 to 6,000 hours, with the time between overhauls growing to 1,500 hours. Another significant improvement is the use of radar absorbing materials (RAM) in various parts of the airframe reducing the fighter's X-band radar cross section within the +/- 60 degree sector.
The Su-35 is powered by the NPO Saturn's izdeliye 117S, the new engine is a much improved derivative of the Su-27's AL-31F turbofan based on the company's earlier AL-41F. In its current form the 117S (designated AL-41F1A) offers 16% more thrust than the standard AL-31F, providing 14,500 kgf in afterburner mode and 8,800 kgf in maximum dry setting. The engine's service life has been increased from 1,500 to 4,000 hours, with time between overhauls increasing from 500 to 1,000 hours. Flight testing started in March 2004 with the 117S fitted to the Su-27M '710' testbed. Two production standard 117S engines now power the first Su-35 prototype. Additional engines are being produced for the next two Su-35 prototypes, while development of even more powerful variants of the engine continues. Production of the 117S is shared between the NPO Saturn plant in Rybinsk and the Ufa Engine Production Association (UMPO) in Ufa.
The Su-35 new fire control system consists of the N035 Irbis multifunction radar system and the OLS-35 electro-optical search-and-track system. The N035 Irbis (Irbis-E for export) is an X-band radar with a 900mm passive phased array. Developed by the Tikhomirov NIIP institute the Irbis radar is a derivative of the N011M Bars radar with wider search zone, increased detection range, wider range of operating frequencies and improved resistance to jamming.
The N035's computing system consists of two Russian Solo-35 processors. A new two-stage mechanical drive mounts the phased array. The passive electronic array scans 60° in azimuth and elevation, while the mechanical steering enables the array to rotate an additional 60° for a wider search zone. The Irbis-E is capable of tracking of up to 30 aerial targets in track-while-scan mode and allows simultaneous engagement of two targets using semi-active radar homing missiles or up to eight targets using active radar homing missiles. The Irbis-E is advertised to be capable of detecting and tracking a fighter-sized target head-on at 350-400 km range using its long-range detection mode within a limited sector. It is also claimed to be capable of detecting 'super-low-observable' targets with 0.01 sq.m RCS at 90 km range.
For ground attack, the radar is capable of terrain mapping and target acquisition in different resolutions using Doppler beam sharpening and synthetic aperture focusing modes. In combined ground and air mode, the radar is capable of tracking aerial threats with sufficient precision to engage with active radar homing missiles.
Future options for the Su-35 might include a rear-facing radar such as the N012 to be fitted in the tailboom, but the current Su-35 does not contain such equipment.
Developed by the UOMZ (Ural Optical and Mechanical Plant) in Yekaterinburg, the OLS-35 infrared/laser search-and-track (IRST) system provides the second major sensor of the Su-35's fire control system. The OLS-35 combines a scanning infra-red direction finder and thermal imaging module for target detection and identification with a laser rangefinder/designator and TV camera. The OLS-35 offers sigficant improvements over the OLS-27 of previous Su-27 versions, owing to the use of more advanced electronics, algorithms and software. Information regarding detection ranges and detection/tracking zones vary across sources. The estimated range for detection from a tail-on aspect has been reported to be 70-90 km and up to 40-50 km for head-on engagement for non-afterburning targets. The detection and tracking zone is 55-60 ° upwards, 15 ° downwards, and between 60° and 90° in azimuth. The laser is capable to range aerial target up to 20 km and ground targets at 30 km with a precision of five meters. Alternatively, the Su-35 may be fitted with one of the new electro-optical systems developed by NIIPP (Scientific Research Institute of Precision Instruments Engineering) for the MiG-35.
As with all 4th and 5th generation fighter aircraft, the human-machine interface received considerable attention from its designers. The integrated avionics suite is controlled by the central information and control system. The 'open architecture' system's main components are two central digital computers, digital databus and the 'glass cockpit' display system. The latter consists of two 15" (9x12") MFI-35 full-colour multifunction LCD with 1400x1050 pixels, a multifunction control panel with built-in display unit, IKSh-1M wide-angle collimator HUD and control display unit. The Su-35 cockpit retains the conventional central stick and throttle arrangement of the Su-27, but incorporates the HOTAS principle.
Just like previous Su-27 derivatives, the Su-35 is capable of carrying a maximum payload of 8,000 kg on its 12 external hardpoints. The weapons suite has been further expanded with upgraded variants of existing weapons as well as several new long-range missiles.
The Su-35's air-to-air suite will comprise advanced R-27 versions (R-27ET1, R-27ER1, R-27EP1) and the active R-77 and new R-77M for medium range missiles, the R-73 and new R-74M short range missiles. Up to 12 R-77/R-77M can be carried, with two pairs placed between the nacelles. The Su-35 will also be able to equip up to five long-range missiles. Dubbed 'very-long-range' air-to-air missile, the K-100-1 (izdeliye 172S, 172S-1) has been developed by Novator in Yekaterinburg from its earlier K-172, which was first developed in 1991 for the Su-27M. The missile has a range of 300-400km and is capable of reaching speeds up to 4,000km/h pulling up to 9Gs to attack targets flying at altitudes ranging from 3m to 30,000m.
Air-to-surface missiles include up to six Kh-29T/L AGM, Kh-31A AShM, Kh-31P ARM, or up to five Kh-59MK longe-range AShM, Kh-58UShE extended range ARM, or up to three Kalibr-A long-range AShM, or one Yakhont heavy long-range AShM. Other air-to-surface weapons include a wide selection of guided bombs as well as unguided bombs and rockets. Laser-guided rockets are also planned to be added to the Su-35's arsenal.
Sukhoi's 'intermediate fighter program' has already seen several delays. Sukhoi originally planned to start series production of the new type in 2007. The deadline was then changed to 2009 and the second prototype was scheduled to be ready in mid-2007 and to be fitted with the Irbis-E in August 2007. However by August 2007, Sukhoi and KnAAPO were barely able to unveil the first Su-35 prototype in the static show at the MAKS 2007 air show. On February 19, 2008, the first prototype Su-35-1 '901' finally made its maiden flight and Sukhoi issued a press release reporting 2010-2011 for the start of series production. The second prototype Su-35 '902' made its maiden flight on 2 October 2008, flown by Sergey Bogdan from the KnAAPO factory's Dzemgi airfield at Komsomol'sk-na-Amur. KnAAPO announced on March 23, 2009, that the first two prototypes had completed 100 flights, finalizing testing of the flight control system.
The third prototype built is solely used for ground testing. The fourth aircraft built would be the third flying prototype, but it was destroyed on April 26, 2009, prior to its scheduled first flight the next day. The aircraft ran off the runway at Komsomol'sk-na-Amur during high-speed taxi tests, hitting an obstacle causing a destructive fire. Test pilot Eugene Frolov was able to eject and escape unhurt.
The Su-35-1 '901' prototype did not feature the full mission systems suite. The second and third prototypes were planned to receive full mission equipment, with '902' devoted to mission systems and integration testing. Following the incident with the third flying prototype, KnAAPO stated the development programme should not be affected by the loss due to the success with the first two aircraft.
As the original Russian procurement budget for 2007-2015 did not provide funding for the acquisition of new fighter aircraft, Sukhoi originally envisaged the Su-35 mainly for export customers. Only provisions had been made for PAK-FA development and the Su-27SM upgrade program of the existing fleet of Su-27s. Having been introduced to the new Su-35 and also MiG-35 at MAKS 2007, premier Putin suggested a revision of the defence procurement budget to include these new aircraft. After the five-day war with Georgia during the summer of 2008, the Russian Air Force need for modernization became even more apparent. Due to delays in the PAK-FA development programme, the Russian Air Force wanted to buy Su-35s as interim fighter. With the global economic crisis the Russian government also decided to boast the Russian economy by investing in the defence sector. For Sukhoi this materialized in a $80 billion Rubles ($2.5 billion USD) contract for 12 Su-27SM3, four Su-30M2, and 48 new-built Su-35s, signed on August 18, 2009. All 48 Su-35 are to be delivered by 2015.
Sukhoi announced on November 17, 2009, that KnAAPO had begun component production for the initial production batch. Assembly of the first series production aircraft for the Russian Air Force is planned to start in 2010. The domestic version is reportedly designated Su-35S and will differ from export versions by having local IFF, electronic warfare and communication systems. The Irbis radar is also likely to have additional operating modes compared to its export version.
Su-35 / Su-27BM
Powerplant: two 142.2 kN (31,970 lb st) NPO Saturn / UMPO AL-41F1 (izdeliye 117S) afterburning turbofans
Length 21.9 m (71 ft 10 in)
Height 5.9 m (19 ft 4 in)
Wing span 15.3 m (50 ft 2.5 in)
Empty weitht 18,400 kg (40,570 lb)
Normal Take-Off Weight 25,300 kg (55,780 lb)
Max Take-Off Weight 34,500 kg (76,060 lb)
Internal Fuel: 11,500 kg (25,350 lb)
Max level speed at 11,000m (36,000 ft) Mach 2.25 or 2,400 km/h (1,490 mph)
Max level speed sea level 1,400 km/h (870 mph)
Service ceiling 18,000 m (59,000 ft)
Armament: one GSh-301 30mm cannon with 150 rounds
Bombload: 8,000 kg (17,640 lb)
Powerplant: two 142 kN (31,924 lb st) Saturn Lyul'ka AL-31FM (AL-35F) afterburning turbofans
Length 22.183m (72 ft 9 in)
Height 6.43m (21 ft 5 in)
Wing span 14.7m (48 ft)
Empty 18400 kg (40,564 lb)
Max Take-Off Weight 34000 kg (74,956 lb)
Max level speed at high altitude Mach 2.35 or 2500 km/h (1,553 mph)
Max level speed at sea level 1400 km/h (870 mph)
Service ceiling 18,000m (54,000 ft)
Armament: one GSh-301 30mm cannon with 150 rounds
Bombload: 8000 kg (17,637 lb