Designed as a counter to the excellent American swing-wing Grumman F-14 "Tomcat" carrierborne fleet defender and the classic McDonnell Douglas F-15 "Eagle" air superiority fighter, the Soviet/Russian Sukhoi Su-27 "Flanker" became an instant classic when introduced into service during June of 1985. The twin-engined heavy platform evolved from its air superiority roots to become a complete multirole fighter during its lengthy time aloft. Even today the series continues as a frontline answer to the West's 4th Generation types and the line has evolved to include the related Su-30, Su-33 and Su-35 as well as several Chinese-originated offshoots. It is expected that the Su-27 family will maintain a presence over the modern battlefield for some decades more even as the in-development Sukhoi T-50 PAK-FA (detailed elsewhere on this site) makes its appearance in suitable numbers for the Russian Air Force.
Origins of the Su-27 place it back in the 1970s when the Soviet Air Force and Ministry of Aircraft Industry joined resources to study concepts for future Soviet fighter platforms. Multirole models were the call of the day - a single aircraft to accomplish various roles such as interception, air defense neutralization and ground attack. Air powers typically adopted two aircraft classes to meet the need - a medium-to-heavy model alongside a lightweight performer. For the United States, this ultimately became the F-15/F14 paired with the General Dynamics F-16 "Fighting Falcon".
For the heavy-class fighter, the Soviet focus fell to a design expected to showcase excellent performance and maneuverability despite its size while the lightweight aircraftlwent on to become the Mikoyan MiG-29 "Fulcrum". The heavy fighter force would account for over one-quarter of the Russian Air Force fleet, the lightweight development used to fill the rest of the stock - built along the lines of economic mass production and readily available to Soviet export allies around the world.
Central Research and Development Institute No. 30 pressed ahead and drew up plans for a new heavy fighter form, giving it a sleek, wing-body blending shape with twin vertical tail fins set atop and a twin engine arrangement. The wing-body arrangement provided the strength needed to carry large, heavy war loads and the twin engine configuration offered the necessary power and survivability needed of a high performance combat craft (should one engine be lost in combat, the aircraft held a better chance of returning home with the intact powerplant still in play). Situational awareness for the pilot was to be handled by an advanced onboard suite as well as a bubble-style canopy offering excellent all-around vision. Powerful scan-and-tracking radar would be fitted in the nosecone.
The design was designated internally as "T10" and constituted the blended wing-body form (as the "T10-1") alongside a more conventional winged design (the "T10-2"). The latter design was dropped when it was deemed the advantages of the first offering were worth the risk and investment. With the design more or less fleshed out, power-players Sukhoi, Mikoyan and Yakovlev competed for the Ministry contract with a formal Air Force review coming in 1972. The Sukhoi design won out while Mikoyan was selected to fulfill the lightweight fighter requirement (producing the MiG-29). Engineering work continued on the T10 leading to many refinements until finalization was had by 1975. Construction on the flyable prototype was then begun.
Engines used to power the fighter would come from Lyulka and they produced the AL-31F turbofan engine. With origins in the AL-21F-3 afterburning turbojet, the AL-31 series also offered afterburner capability and two of its kind would be used to power the Sukhoi prototype.
Should the aircraft come to pass, the T10 would become the first Soviet aircraft to feature a true Fly-By-Wire (FBW) controlling with no mechanical linkage set between the control systems and the wing surface areas. Avionics would of course be state-of-the-art for the time and include a Head-Up Display (HUD) offering pertinent performance and mission information. A Fire Control Radar (FCR) and electro-optoelectronic targeting system would make the fighter a lethal adversary by assisting the pilot in all facets of targeting and engagement. Like the MiG-29, the Sukhoi T10 would also be fitted with an avionics suite largely digital in nature - another Soviet first for a combat aircraft.
All new missiles were also in development to round out the list of components necessary in bringing to life a frontline fighting machine to contend with anything the West could offer now and in the near future.
The T10 prototype recorded its first flight on May 20th, 1977 and managed nearly forty flights into January of 1978 before ending its days as a museum showpiece. Early testing magnified aerodynamic issues that were appropriately dealt with. However, the program suffered a major setback when the second prototype was lost in a fatal crash on May 7th, 1978.
That same year, work began on construction of the third prototype which introduced outward-canted tailfins as well as being outfitted with the AL-31F series engines. This forced a major revision of the engine housings from intake to exhaust port to accommodate the powerplants. The aircraft was used as both an engine testbed and as a naval fighter prototype - completing ski-jump take-offs and being finished with arrestor gear and a reinforced undercarriage for the role. For 1983, a fourth prototype joined the stable for service as an avionics and weapons testbed. It claimed its first flight in October of 1979. A long range of prototypes then followed including high-speed, high-performance types intended for record-setting exercises. Even as the Su-27 entered serial production and frontline service, development continued on bettering the line.
The Su-27 managed a plethora of variants and designations throughout its flying career. The original prototype was the aforementioned "T10" (known to NATO as "Flanker-A") and T10S followed with an improved configuration mimicking production standard Flankers more closely. "Su-27" was used to mark pre-production vehicles with the AL-31 series engine. Rounded wingtips were a physical difference of early Su-27 aircraft.
The initial production-quality fighter became "Su-27S" (NATO codename of "Flanker-B") and these were single-seat fighters fitted with improved AL-31F engines, leading edge slats, and clipped wingtips. The vertical tail surfaces were moved further outboard as well. Su-27P became an air superiority / interceptor model lacking ground attack functionality, primarily issued to the Soviet Air Defense Forces. Su-27PU (to become the Su-30) evolved into a two-seat model based on the Su-27P interceptor - these carried equipment to help support older Soviet fighters then in service. The mark was later revised to become multirole platforms for export.
Su-27UB became two-seat trainers ("Flanker-C") arriving in 1986 with a second cockpit for the instructor (at the expense of internal fuel and operating range). The Su-27S was exported as "Su-27SK" and the "Su-27UB" two-seat trainer was sold abroad as the "Su-27UBK". China evolved the Su-27SK as the Shenyang J-11 (detailed elsewhere on this site). Trainer forms retained all of their combat capability despite their primary role of flying classroom.
The Su-27SK variant was given an overall length of 72 feet, a wingspan of 48.2 feet and a height of 19.5 feet. Empty weight was 36,100 lb against a Maximum Take-Off Weight (MTOW) of 67,100 lb. Power is from 2 x Lyulka (Saturn) AL-31F turbofan engines developing 16,910 lb of dry thrust and 27,560 lb of thrust with afterburner engaged. Maximum speed reached Mach 2.35 or 1,550 miles per hour at altitude. Range is out to 2,200 miles and a service ceiling of 62,523 feet is reported. Rate-of-climb is listed at 59,000 feet-per-minute.
The Su-27SK carried a standard, fixed armament in the form of 1 x GSh-30-1 series internal cannon with 150 rounds afforded. Ten external hardpoints were in play capable of carrying up to 9,770 lb of stores for either Air-to-Air (AA) or Air-to-Surface (AS) sorties. A typical fighter/interceptor loadout became 6 x R-27 medium-range AA missiles with 2 x R-73 short-range AA missiles. Those Flankers equipped for ground attack had their armament load capabilities broadened considerably and carried anything from conventional drop stores and precision-guided munitions to guided missiles and rocket pods. Specialized mission forms were also forged, these equipped with anti-ship and anti-radar missiles.
Su-27IB was the prototype for the "Su-32", a two-seat long-range strike fighter development of the Su-27 (akin to the American General Dynamics F-111 "Aardvark" fighter bomber). This influenced the Su-32FN and Su-34 "Fullback" developments (detailed elsewhere on this site) developments. The Fullback, now in frontline operation, is easily distinguished from its Su-27 roots by the "platypus" nose design and side-by-side seating for the crew. The aircraft carries an onboard toilet with a sleep area for the crew to provide some comfort for extremely long-range mission sets. The undercarriage main legs are also revised with additional wheels for the added weight of the redesign but the Su-27 origins are still clearly visible in the Su-34 design as a whole.
The Su-27K emerged as a carrier-based fighter and eventually became the "Su-33" in service ("Flanker-D" to NATO) for the Soviet-Russian Navy. These were still single-seat models but given carrier fighter qualities such as folding wings, arrestor gear, reinforced undercarriages and high-lift devices. Production of this mark was very limited. A navalized version of the MiG-29 was also developed.
The single-seat Su-27M existed as a demonstrator and included the Su-35UB of two-seat configuration.
The Super Flanker and Beyond
In 1985, a heavily modified Flanker flew for the first time with all-moving canards and other refinements of the base Su-27 design. This aircraft, based on an Su-27M model, went on to become the Su-35 ("Flanker-E") air superiority fighter (detailed elsewhere on this site). A single-seat model, the Su-35 introduced more powerful engines (AL-41F1S turbofans), all-digital FBW with quadruple redundancy, a new avionics fit, and the new Phazotron radar ranged out to 62 miles. The radar fit offered the ability to track up to twenty-four targets simultaneously. An in-flight refueling capability added nearly-infinite operational range. Three Multi-Function Display (MFD) units were installed in the cockpit for improved mission performance.
The Su-35 entered service in limited numbers and is also known as the "Super Flanker". When fully modernized, the Su-35 is said to be a 4++ Generation fighter intended to serve as a bridge product between older Flankers and the upcoming T-50 PAK FA Fifth Generation fighter.
The Su-37 ("Flanker-F") arrived as improved form of the Su-35 Super Flanker. Thrust-vectoring nozzles were installed at the engine exhaust to offer amazing inherent agility when coupled to the digital FBW system already in place. A fourth MFD was installed in the cockpit as was a sidestick control scheme. Only two Su-37s were built from existing Su-35 airframes and a first flight was had on April 2nd, 1996. Development of this aircraft was abandoned making it more of a technology demonstrator than a probable production aircraft.
The Su-47 "Berkut" (detailed elsewhere on this site) became another technological demonstrator born from the Su-27 line. The most noticeable change was its wing mainplanes which were swept forward while the aircraft retained much of the form and function of the original Su-27. Only one example was completed and saw testing by the Russian Air Force. A first flight was had on September 25th, 1997. The product proved (and disproved) many 4.5 Generation Fighter components which were to be featured later in Sukhoi fighter designs - including the upcoming PAK FA.
After the fall of the Soviet Empire, the Su-27 continued its progression. The Su-27PD served as a single-seat demonstrator but instituted an in-flight refueling probe. The Su-30M/Su-30MK forms were modernized two-seat multirole fighters that found more success in export than in local service. A mid-life upgrade of the Su-27S brought about the "Su-27SM" designation ("Flanker-B Mod. 1") and these used components proven in the Su-27M demonstrator. The Su-27SKM single-seat multirole performer became an export product of the Su-27SK - key features becoming an improved Electronic CounterMeasures (ECM) suite, an in-flight refueling probe, and modernized cockpit. The Su-27UB became the modernized two-seat trainer version.
Su-27SM2 marked a 4th+ Generation Fighter upgrade to Su-27s in service with the Russian Air Force. These included technologies proven on the Su-35BM platform with more powerful radar and AL-41F1S engines.
While the Soviet Union fell to history and Belarus gave up on their use of the Su-27 (some sold to Angola), operators of the Flanker remain plenty today (2015). This includes Angola, China, Eritrea, Ethiopia, Indonesia, Kazakhstan, Russian, Ukraine, Uzbekistan, Vietnam, and the United States (two purchased in 2009 from a private entity and used as aggressors in training). The Ukrainian inventory has consistently shrunk to feature just sixteen airworthy examples in 2015 (from a peak of seventy). Ukraine was once the most numerous Su-27 operator after Russia.
The Su-27 achieved Initial Operating Capability (IOC) during December of 1984 and saw its formal introduction come on June 22nd, 1985. When the West learned of the aircraft it provided the working name of "Ram-K" until 1982 when the series received the official "Flanker" name.
The Su-27 provided the Russian Air Force with an exceptional aircraft of considerable operating range and armament loadout. It was larger than the competing F-15 Eagle and, through its powerful nose-mounted radar, was given a tremendous scan-while-track ability against targets Beyond-Visual-Range (BVR) - even at tree top levels. It could be used as interceptor, trainer, fighter and ground attack platform with consistent effectiveness across all sortie types. Range was such that the fighters could escort a flight of Russian strategic bombers to the British homeland and back - all the while possessing the performance and systems to tangle with enemy fighters directly. It was a proper counter to enemy bombers such as the Boeing B-52 "Stratofortress" conventional bomber and the more advanced Rockwell B-1 "Lancer" stealth bomber.
Due to the success of the Su-27 platform and its progressive evolution, the Flanker line will remain in frontline service with Russian forces a while longer - at least until the PAK FA gains a foothold in the Air Force inventory. For other global operators, the Su-27 will continue to see operational-level use for decades to come. Certainly one of the best fighter aircraft of its generation, the Su-27 has become the pinnacle of Soviet-Russian fighter development - a true classic alongside the F-14 and F-15 lines offered by the Americans (the F-14 has already been retired from USN service and plans are being laid to modernized the F-15 to keep it a viable fighting platform for decades to come).