Su-27 Flanker

The Sukhoi Su-27 (NATO reporting name Flanker) is a twin-engine supersonic air superiority fighter developed in the Soviet Union as the heavy counterpart to the MiG-29 and the answer to the F-15 Eagle. It entered Soviet service in 1985 as a long-range interceptor and bomber escort, combining a 3,530 km (1,910 nmi) range, ten hardpoints and a powerful radar with agility that extends to controlled flight at extreme angles of attack. The airframe is the root of the whole Flanker family — Su-30, Su-33, Su-34, Su-35 and the Chinese J-11 — and the original Su-27s remain in service with about ten air forces as of 2026, flown in combat by both sides of the Russo-Ukrainian war.

Development

In 1969 the Soviet General Staff, alerted to the US F-X programme that produced the F-15, issued a requirement for an advanced frontline fighter (PFI) with long range, austere-field performance, Mach 2+ speed and heavy armament. Too costly for a single type, the specification was split: the lightweight LPFI became Mikoyan's MiG-29, the heavy TPFI went to Sukhoi, whose work with TsAGI produced a blended wing-body flown slightly unstable under fly-by-wire control, with a wide tunnel between two podded engines that generates lift and shields underslung weapons from radar.

The first prototype, the T-10-1, flew on 20 May 1977 on AL-21 turbojets. By 1980 trials with the intended AL-31 turbofan and the Mech radar had shown that aerodynamics, avionics weight and fuel consumption all missed the requirement, and Sukhoi undertook a complete redesign: the T-10S, flown on 20 April 1981, shared little but the layout with the T-10 and became the pattern for production. Two T-10S prototypes were lost that year and structural failures persisted into 1984.

Deliveries began in 1985, although production problems delayed large-scale service until about 1990; conversion training used the tandem two-seat Su-27UB (Flanker-C). Export Su-27SK and Su-27UBK versions followed in 1991, and the carrier-capable Su-27K became the Su-33, covered on its own page.

Design

The Su-27 is aerodynamically similar to the MiG-29 but considerably larger: 21.9 m (71 ft 10 in) long, 14.7 m (48 ft 3 in) in span, with 9,400 kg of internal fuel. The cropped semi-delta wing is attached through large leading-edge root extensions, with conventional tailplanes and twin fins outboard of the nacelles. Two Saturn AL-31F afterburning turbofans deliver 12,500 kgf (122.6 kN) each with reheat, for 2,500 km/h (Mach 2.35) at altitude and a thrust-to-weight ratio above one at typical combat weights.

The aircraft carried the Soviet Union's first operational fly-by-wire system, which with low wing loading keeps it controllable at very low speed and high angle of attack; the "Cobra" demonstrated from 1989 — a momentary pitch-up to about 120 degrees in level flight — is flown on the basic airframe with conventional nozzles, thrust vectoring belonging only to later derivatives (Su-30MKI/SM, Su-35S, the Su-37 demonstrator). The N001 Myech pulse-Doppler radar offers track-while-scan and look-down/shoot-down modes, paired with an OLS-27 infrared search-and-track set ahead of the windscreen and a helmet-mounted sight.

Modernisation

Russia began a mid-life upgrade of its fleet in 2004 as the Su-27SM: multifunction displays, a new mission computer, a radar with a synthetic-aperture ground-mapping mode, the Pastel radar warning receiver and Khibiny jammers. For the first time the Su-27 could employ guided air-to-ground weapons — Kh-29 and Kh-31 missiles, KAB-500/1500 bombs — and the active-radar R-77. The Su-27SM3 adds a strengthened airframe with two extra underwing stations, three tonnes more take-off weight, AL-31F-M1 engines and the R-77-1; the Irbis-E-equipped Su-27SM2 was dropped on cost grounds. Ukraine's Zaporizhzhia plant produced a more modest upgrade from 2012 (Su-27P1M, Su-27UB1M) to radar, navigation and communications.

Armament

One 30 mm GSh-30-1 cannon with 150 rounds sits in the starboard wing root. Ten hardpoints carry up to 4,430 kg (9,770 lb) of stores, typically R-27 (AA-10 Alamo) medium-range missiles in semi-active radar and infrared versions alongside R-73 (AA-11 Archer) short-range missiles; upgraded aircraft add the R-77 (AA-12 Adder). Air-to-ground options on the basic aircraft are limited to unguided bombs, rockets and cluster munitions. Ukrainian aircraft have been adapted to US weapons, carrying AGM-88 HARM anti-radiation missiles from September 2022 and JDAM-ER glide bombs from 2023.

Operational History

Soviet and Russian service

The first frontline unit was the 831st Fighter Aviation Regiment at Myrhorod, in the Ukrainian SSR, from November 1985. On 13 September 1987 an armed Su-27 collided with a Norwegian P-3 Orion over the Barents Sea during close passes; both aircraft landed safely. Russian Su-27s flew in the 1992–93 Abkhazia war, where one fell to friendly surface-to-air fire, and secured the airspace over Tskhinvali in the 2008 war with Georgia. A squadron of Su-27SM3s deployed to Syria in November 2015, and the type continues to fly intercepts along Russia's borders.

Africa

Ethiopia bought eight surplus Su-27s in 1998 during its war with Eritrea; in February 1999 they shot down two Eritrean MiG-29s and damaged a third, with further claims in May 2000 that Eritrea denies. In the Tigray war of 2020–22 Ethiopia used the type as a bomber with OFAB-250 unguided bombs over Mekelle, and in August 2022 the government said one had shot down an An-26 entering from Sudan. Angola's ex-Belarusian Su-27s entered service in 2000 during the civil war; one was reportedly brought down by a UNITA Strela-3 missile that November while landing.

Russo-Ukrainian war

Ukraine inherited roughly 70 Su-27s in 1991 but, starved of funds and spare parts, had only 19 serviceable when Russia annexed Crimea in 2014 and about 34 in service in 2019, flying top cover over the Donbas. Both sides fly the type in the full-scale war begun on 24 February 2022. Ukraine lost aircraft on the first day in a strike on Ozerne air base, another to a Russian S-400 battery over Kyiv on 25 February and several more that year. The fleet nevertheless took on strike work — a pair bombed Russian positions on Snake Island at low altitude on 7 May 2022 — with HARM and later JDAM-ER. Russian ballistic-missile strikes on Myrhorod air base destroyed several aircraft parked in the open in June–August 2024, and losses continued through 2025 and into 2026, including a Su-27UP2M shot down near Kharkiv in May 2024 and a brigade commander killed in air combat over eastern Ukraine in March 2026. By April 2026 Ukraine had lost 19 Su-27s in the war, against three Russian aircraft. On 14 March 2023 a Russian Su-27 dumped fuel on and then struck the propeller of a US MQ-9 Reaper over the Black Sea, forcing the drone down in international waters.

Operators

Russia remains the largest operator, with about 100 Su-27s of the S, SM and SM3 standards in the Aerospace Forces as of 2026 and a handful with Naval Aviation, a fleet shrinking as the Su-35S and Su-57 take over. Ukraine had some 24 in service as of early 2026. China took 76 Soviet- and Russian-built aircraft between 1991 and 2009 and built 100 more as the J-11A under licence from 1998; its two-seat Su-27UBKs remain in service. Ethiopia, Uzbekistan and Kazakhstan follow with some 10–20 each; Vietnam has ten Su-27SK/UBK and Indonesia five Su-27SK/SKM, while Eritrea and Angola keep a few. Belarus retired its Su-27Ps in 2012, and the US Air Force has bought a few for evaluation.

Accidents

Three Russian Knights aircraft flew into terrain near Cam Ranh in December 1995 while following their Il-76 support aircraft, and a Ukrainian Su-27UB crashed into the crowd at Sknyliv on 27 July 2002, killing 77 spectators in the deadliest air show disaster on record.

Variants

• Su-27S (Flanker-B): Initial production single-seater; the standard Soviet and Russian fighter.
• Su-27P: Air Defence Forces interceptor without air-to-ground weapons wiring.
• Su-27UB (Flanker-C): Tandem two-seat conversion trainer, retaining combat capability.
• Su-27SK / Su-27UBK: Export versions from 1991 with strengthened landing gear; China, Vietnam, Ethiopia and Indonesia. The Su-27SKM adds a glass cockpit and refuelling probe (Indonesia).
• Su-27SM (Flanker-E): Russian mid-life upgrade from 2004 with guided air-to-ground weapons and the R-77.
• Su-27SM3: Strengthened SM with two extra stations, AL-31F-M1 engines and R-77-1 compatibility.
• Su-27P1M / UB1M / UP2M: Ukrainian upgrades from 2012.
• Su-27K: Carrier version, produced as the Su-33 (separate page); the Su-27PU became the Su-30, the Su-27IB the Su-34.
• Shenyang J-11: Chinese licence-built Su-27SK (J-11A, 100 built), developed into the J-11B with Chinese systems.