In the early 1950s, the Soviet Union delivered hundreds of MiG-15s to China, where they received the designation J-2. The Soviets also sent almost a thousand MiG-15 engineers and specialists to China, where they assisted China's Shenyang Aircraft Factory in building the MiG-15UTI trainer (designated JJ-2). China never produced a single-seat fighter version, only the two-seat JJ-2.^[69]

The designation "J-4" is unclear; some sources claim Western observers mistakenly labelled China's MiG-15bis a "J-4", while the PLAAF never used the "J-4" designation. Others claim "J-4" is used for MiG-17F, while "J-5" is used for MiG-17PF.^[70] Another source claims the PLAAF used "J-4" for Soviet-built MiG-17A, which were quickly replaced by license-built MiG-17Fs (J-5s).^[71]What is certain, is that the service lives of the J-2 and J-4 in the PLAAF were short, as they were quickly replaced by the more capable J-5 and J-6.^{[citation needed]}

Like many aircraft designed as interceptors, the MiG-21 had a short range. This was exacerbated by the poor placement of the internal fuel tanks ahead of the center of gravity. As the internal fuel was consumed, the center of gravity would shift rearward beyond acceptable parameters. This had the effect of making the plane statically unstable to the point of being difficult to control, resulting in an endurance of only 45 minutes in clean condition. This can be somewhat countered by carrying fuel in external tanks closer to the center of gravity. The Chinese variants somewhat improved the internal fuel tank layout (also second generation of Soviet variants), and also carry significantly larger external fuel tanks to counter this issue.^[3] Additionally, when more than half the fuel was used up, violent maneuvers prevented fuel from flowing into the engine (questionable), thereby causing it to shut down in flight. This increased the risk of tank implosions (MiG-21 had tanks pressurized with air from the engine's compressor), a problem inherited from the MiG-15, MiG-17 and MiG-19.^[4] The short endurance and low fuel capacity of the MiG-21F, PF, PFM, S/SM and M/MF variants—though each had a somewhat greater fuel capacity than its predecessor—led to the development of the MT and SMT variants. These had an increased range of 250 km (155 mi) compared to the MiG-21SM, but at the cost of worsening all other performance figures, such as a lower service ceiling and slower time to altitude.^[1]

A pole mounted MIG-21

The delta wing, while excellent for a fast-climbing interceptor, meant any form of turning combat led to a rapid loss of speed. However, the light loading of the aircraft could mean that a climb rate of 235 m/s (46,250 ft/min) was possible with a combat-loaded MiG-21bis,^[1] not far short of the performance of the later F-16A. Given a skilled pilot and capable missiles, it could give a good account of itself against contemporary fighters. Its G-limits were increased from +7Gs in initial variants to +8.5Gs in the latest variants.^[5] It was replaced by the newer variable-geometry MiG-23 and MiG-27 for ground support duties. However, not until the MiG-29 would the Soviet Union ultimately replace the MiG-21 as a maneuvering dogfighter to counter new American air superiority types.

The MiG-21 was exported widely and remains in use. The aircraft's simple controls, engine, weapons, and avionics were typical of Soviet-era military designs. The use of a tail with the delta wing aids stability and control at the extremes of the flight envelope, enhancing safety for lower-skilled pilots; this in turn enhanced its marketability in exports to developing countries with limited training programs and restricted pilot pools. While technologically inferior to the more advanced fighters it often faced, low production and maintenance costs made it a favorite of nations buying Eastern Bloc military hardware. Several Russian, Israeli and Romanian firms have begun to offer upgrade packages to MiG-21 operators, designed to bring the aircraft up to a modern standard, with greatly upgraded avionics and armaments.^[1]

The Su-25 has a conventional aerodynamic layout with a shoulder-mounted trapezoidal wing and a traditional tailplane and rudder. Several metals are used in the construction of the airframe: 60% aluminium, 19% steel, 13.5% titanium, 2% magnesium alloy and 5.5% other materials.

Su-25 at Kubinka air base

All versions of the Su-25 have a metal cantilever wing, of moderate sweep, high aspect ratio and equipped with high-lift devices. The wing consists of two cantilever sections attached to a central torsion box, forming a single unit with the fuselage. The air brakes are housed in fairings at the tip of each wing. Each wing has five hardpoints for weapons carriage, with the attachment points mounted on load-bearing ribs and spars. Each wing also features a five-section leading edge slat, a two-section flap and an aileron.

The flaps are mounted by steel sliders and rollers, attached to brackets on the rear spar. The trapezoidal ailerons are near the wingtips. The fuselage of the Su-25 has an ellipsoidal section and is of semi-monocoque, stressed-skin construction, arranged as a longitudinal load-bearing framework of longerons, beams and stringers, with a transverse load-bearing assembly of frames. The one-piece horizontal tailplane is attached to the load-bearing frame at two mounting points.

Early versions of the Su-25 were equipped with two R95Sh non-afterburning turbojets, in compartments on either side of the rear fuselage. The engines, sub-assemblies and surrounding fuselage are cooled by air provided by the cold air intakes on top of the engine nacelles. A drainage system collects oil, hydraulic fluid residues and fuel from the engines after flight or after an unsuccessful start. The engine control systems allows independent operation of each engine.The latest versions (Su-25T and TM) are equipped with improved R-195 engines.

Nose view of the Su-25

The cannon is in a compartment beneath the cockpit, mounted on a load-bearing beam attached to the cockpit floor and the forward fuselage support structure. The nose is fitted with distinctive twin pitot probes and hinges up for service access.

Su-25T

The Su-25T (Tankovy) is a dedicated antitank version, which has been combat-tested with notable success in Chechnya.^[15] The design of the aircraft is similar to the Su-25UB. The variant was converted to one-seater, with the rear seat replaced by additional avionics.^[78] It has all-weather and night attack capability. In addition to the full arsenal of weapons of the standard Su-25, the Su-25T can employ the KAB-500Kr TV-guided bomb and the semi-active laser-guided Kh-25ML.^[15] Its enlarged nosecone houses the Shkval optical TV and aiming system with the Prichal laser rangefinder and target designator. It can also carry Vikhr laser-guided, tube-launched missiles, which is its main antitank armament. For night operations, the low-light TV Merkuriy pod system can be carried under the fuselage. Three Su-25Ts prototypes were built in 1983–86 and 8 production aircraft were built in 1990.^[79] With the introduction of a definitive Russian Air Force Su-25 upgrade programme, in the form of Stroyevoy Modernizirovannyi, the Su-25T programme was officially canceled in 2000.^[80]

The T-10S-3 was modified and officially designated the P-42, setting a number of world records for time-to-height, beating those set in 1975 by a similarly modified F-15 called "The Streak Eagle".^[8] The P-42 "Streak Flanker" was stripped of all armament, radar and operational equipment. The fin tips, tail-boom and the wingtip launch rails were also removed. The composite radome was replaced by a lighter metal version. The aircraft was stripped of paint, polished and all drag-producing gaps and joints were sealed. The engines were modified to deliver an increase in thrust of 1,000 kg (2,200 lb), resulting in a thrust-to-weight ratio of almost 2:1 (for comparison with standard example see Specifications).^[9][10]

The production Su-27 (sometimes Su-27S, NATO designation 'Flanker-B') began to enter VVS operational service in 1985, although manufacturing difficulties kept it from appearing in strength until 1990.^[11] The Su-27 served with both the V-PVO and Frontal Aviation. Operational conversion of units to the type occurred using the Su-27UB (Russian for "Uchebno Boevoy" - "Combat Trainer", NATO designation 'Flanker-C') twin-seat trainer, with the pilots seated in tandem.^[12]

When the naval Flanker trainer was being conceived the Soviet Air Force was evaluating a replacement for the Su-24 "Fencer" strike aircraft, and it became evident to Soviet planners at the time that a replacement for the Su-24 would need to be capable of surviving engagements with the new American F-15 and F-16. The Sukhoi bureau concentrated on adaptations of the standard Su-27UB tandem seat trainer. However the Soviet Air Force favoured the crew station (side-by-side seating) approach used in the Su-24 as it worked better for the high workload and potentially long endurance strike roles. Therefore, the conceptual naval side-by-side seated trainer was used as the basis for development of the Su-27IB (Russian for "Istrebityel Bombardirovshchik" - "Fighter Bomber") as an Su-24 replacement in 1983. The first production airframe was flown in early 1994 and renamed the Su-34 (NATO reporting name 'Fullback').^[13]

A Su-33 onboard Admiral Kuznetsov in 1996. U.S. Navy sailors from USS San Jacinto are visiting the carrier.^[20]

Compared with the rival MiG-29K, the Su-33's maximum takeoff weight (MTOW) is 50% higher; fuel capacity is more than double, allowing it to fly 80% further at altitude (or 33% at sea level). The MiG-29K can spend as much time as the Su-33 on station by using external fuel tanks, but this limits its ordnance capacity.^[21] The Su-33 can fly at speeds as low as 240 km/h (150 mph), in comparison the MiG-29K needs to maintain a minimum of 250 km/h (160 mph) for effective control.^[17] However, the MiG-29K carries more air-to-ground munitions than the Su-33.^[17] The Su-33 is more expensive and physically larger than the MiG-29K, limiting the numbers able to be deployed on an aircraft carrier.^{[4][N 2]}

The Su-33 carries guided missiles such as the R-73 (four) and R-27E (six) on twelve hardpoints, supplemented by the 150-round 30 mm GSh-30-1.^[17][24] It can carry an assortment of unguided rockets, bombs and cluster bombs for secondary air-to-ground missions.^[17][24] The aircraft can be used in both night and day operations at sea. The radar used, "Slot Back", has been speculated to have poor multi-target tracking, making the Su-33 reliant on other radar platforms and airborne warning and control system (AWACS) aircraft like the Kamov Ka-31 early-warning helicopter.^[19] The R-27EM missiles have the capability to intercept anti-ship missiles. The infra-red search and track (IRST) system is placed to provide better downward visibility.^[18]

The Pakistan Air Force plans, by 2017, to induct a twin-seater version known as the JF-17B for both enhanced operational capability and training.^[12][13] Preparations for a more advanced and technologically sophisticated block III version of the aircraft are underway and the AESA radar, KJ-7A, has been developed, which can track 15 targets and engage 4 targets simultaneously.^[14]

Since its induction in 2011, the JF-17 Thunder has accumulated 19,000 hours of operational flight.^[15] The JF-17 has seen active military service as it is used by the Pakistan Air Force to bomb militant positions in North Waziristan,^[16] using both unguided munitions and guided missiles for precision strike capability.^[8]

While originally oriented towards combat against any enemy aircraft, many MiG-29s have been furnished as multirole fighters capable of performing a number of different operations, and are commonly outfitted to use a range of air-to-surface armaments and precision munitions. The MiG-29 has been manufactured in several major variants, including the multirole Mikoyan MiG-29M and the navalised Mikoyan MiG-29K; the most advanced member of the family to date is the Mikoyan MiG-35. Later models frequently feature improved engines, glass cockpits with HOTAS-compatible flight controls, modern radar and infrared search and track (IRST) sensors, and considerably increased fuel capacity; some aircraft have also been equipped for aerial refueling.

Following the dissolution of the Soviet Union, the militaries of a number of former Soviet republics have continued to operate the MiG-29, the largest of which is the Russian Air Force. The Russian Air Force wanted to upgrade its existing fleet to the modernised MiG-29SMT configuration, but financial difficulties have limited deliveries. The MiG-29 has also been a popular export aircraft; more than 30 nations either operate or have operated the aircraft to date. As of 2013 the MiG-29 was still in production by Mikoyan, a subsidiary of United Aircraft Corporation (UAC) since 2006.

The MiG-29s continued their service in the subsequent Federal Republic of Yugoslavia. Because of the United Nations arms embargo against the country, the condition of the MiG-29s worsened as aircraft where not maintained according to rules and general overhaul scheduled for 1996 and 1997 was not conducted.^[94]

Six MiG-29s were shot down during the NATO intervention in the Kosovo War, three by USAF F-15s, one by a USAF F-16, and one by a Royal Netherlands Air Force F-16.^[95][96] However, one aircraft, according to its pilot, was hit by friendly fire from the ground.^[97] Another four were destroyed on the ground.^[98] One Argentine source claims that a MiG-29 shot down an F-16 on 26 March 1999,^[99] but this kill is disputed, as the F-16C in question was said to have crashed in the US that same day.^[100]