MiG-31 Foxhound

The Mikoyan MiG-31 (NATO reporting name Foxhound) is a two-seat, twin-engine supersonic interceptor developed in the Soviet Union by the Mikoyan design bureau to replace the MiG-25 Foxbat, on which it is based. The prototype flew on 16 September 1975 and the type entered service with the Soviet Air Defence Forces on 6 May 1981; 519 were built at the Sokol plant up to 1994. It is the fastest known operational combat aircraft, with a top speed of around 3,000 km/h (Mach 2.83). Russia has been its sole operator since Kazakhstan retired its fleet in 2023, and the MiG-31K version carries the Kh-47M2 Kinzhal air-launched ballistic missile, which it has launched against Ukraine during the Russian invasion.

Development

The single-seat MiG-25 offered speed, altitude and climb but lacked manoeuvrability at interception speeds and was difficult to fly at low altitude. Its replacement began as the Ye-155MP, first flown on 16 September 1975, a largely new design with a longer fuselage for a radar operator's cockpit and a radar capable of look-down/shoot-down engagements and multiple-target tracking against low-flying cruise missiles and bombers.

Series production at the Sokol plant began in 1979 and totalled 519 aircraft: 349 baseline MiG-31s up to 1988, 101 MiG-31DZs with refuelling probes in 1989–1991 and a final batch of 69 MiG-31Bs in 1990–1994, of which 50 stayed with Kazakhstan after the Soviet collapse. The more thorough MiG-31M, flown in 1985 with D-30F6M engines, a 52,000 kg (114,600 lb) maximum take-off weight and the Zaslon-M radar, got no further than one prototype and six pre-production aircraft. The MiG-31BM upgrade passed state testing in 2008 and a fleet-wide programme began in 2010 with 100 aircraft to be converted by 2020; 24 had been handed over by April 2015, and a 2014 contract covered 60 conversions to the related MiG-31BSM standard. In 2020 Russia announced that airframe life would be extended from 2,500 to 3,500 hours to keep the type flying until at least 2030; the PAK-DP (MiG-41) replacement launched in April 2013 had not appeared.

Design

Like the MiG-25, the MiG-31 is a large twin-engine aircraft with side-mounted intake ramps, a shoulder-mounted wing of 2.94 aspect ratio and twin fins, but with a second cockpit for a weapon systems officer; both crew sit on zero/zero ejection seats. The structure is 49 percent arc-welded nickel steel, 33 percent light alloy, 16 percent titanium and 2 percent composites, the steel tolerating the kinetic heating of flight approaching Mach 3. The aircraft is 22.62 m (74 ft 3 in) long with a 13.456 m (44 ft 2 in) span, weighs 21,820 kg (48,100 lb) empty and 46,200 kg (101,900 lb) at maximum take-off, and carries 16,130 kg (35,600 lb) of internal fuel. Two Soloviev D-30F6 afterburning turbofans, each rated at 93 kN (20,900 lbf) dry and 152 kN (34,200 lbf) with afterburner, give 1,500 km/h (930 mph; Mach 1.23) at low altitude and a redlined 3,000 km/h (1,860 mph; Mach 2.83) at 21,500 m (70,500 ft). Service ceiling exceeds 25,000 m (82,000 ft); range is 3,000 km (1,860 mi) with four R-33s and two drop tanks, or 5,400 km (3,360 mi) with one refuelling.

The RP-31 N007 Zaslon passive electronically scanned array, adopted in 1981, detects fighter-sized targets at about 200 km (120 mi), originally tracking ten targets and engaging four, later 24 and six, and is paired with an 8TK infrared search-and-track sensor in a retractable fairing under the nose. The APD-518 datalink lets a flight of four MiG-31s up to 200 km (120 mi) apart exchange radar pictures automatically and direct other fighters onto targets. The Zaslon-M of the MiG-31M has a 1.4 m (4.6 ft) antenna and a search range said to be 400 km (250 mi) against an AWACS-sized target.

Armament

A 23 mm GSh-6-23 rotary cannon with 260 rounds is carried internally, a weapon the MiG-25 lacked. Four semi-recessed fuselage stations and four underwing pylons take up to 9,000 kg (19,800 lb). The primary weapon is the Vympel R-33 (AA-9 Amos) long-range missile, four under the belly, with a range of 120 km (75 mi), or 160 km (99 mi) for the R-33S of 1999; the MiG-31BM also fires the R-37M (AA-13 Arrow), a Mach 6 missile with a claimed range of up to 400 km (250 mi), and the R-77; the R-40TD1, R-60 and R-73 cover shorter ranges. Modernised aircraft can carry Kh-31P and Kh-58 anti-radiation missiles, Kh-31A anti-ship missiles, Kh-29T and Kh-59 air-to-surface missiles and KAB-500 and KAB-1500 guided bombs. The MiG-31K carries a single Kh-47M2 Kinzhal hypersonic ballistic missile with a conventional or nuclear warhead, a claimed speed of Mach 10 and a range of about 2,000 km (1,240 mi) including the aircraft's own radius; the modification removed the air-to-air missile equipment, leaving the aircraft solely a strike platform.

Operational History

The MiG-31 entered service with the Soviet Air Defence Forces (PVO) in 1981, and after 1991 the fleet was split between Russia and Kazakhstan. Russian regiments fly it from Monchegorsk, Khotilovo, Perm, Kansk and Tsentralnaya Uglovaya, and Naval Aviation from Yelizovo in Kamchatka; the air force inventory was put at between 85 and 131 MiG-31BMs in 2020. Kazakhstan's 610th Air Base at Sary-Arka kept 31 aircraft in 2022, retired the type in 2023 and put it up for auction.

Over Ukraine, MiG-31s have operated at high speed and altitude beyond the reach of Ukrainian fighters and reportedly shot down several of them with the R-37M. MiG-31Ks, ten of which had been converted by May 2018, have launched Kinzhal missiles: Ukraine said a Patriot battery intercepted one fired from Russian airspace on 4 May 2023, and six Kinzhals launched from six MiG-31Ks at Kyiv on 16 May 2023 were claimed destroyed. Three MiG-31BMs had been visually confirmed lost by 8 September 2024: one that overran the runway at Belbek, Crimea, on 1 October 2022, and two destroyed in a missile strike on Belbek on 15 May 2024. Ukraine claimed to have destroyed another MiG-31 at Belbek on 18 December 2025, and the Security Service of Ukraine said it targeted one there on 26 April 2026. On 19 September 2025 three MiG-31s, without flight plan or transponders, spent 12 minutes in Estonian airspace before Italian F-35s escorted them out, prompting Estonia to request NATO Article 4 consultations.

Variants

• MiG-31 (Izdeliye 01): Baseline production interceptor with the Zaslon radar and four R-33s, built until 1988.
• MiG-31DZ (Izdeliye 01DZ): Baseline aircraft fitted with an in-flight refuelling probe, 101 built in 1989–1991.
• MiG-31B (Izdeliye 01B): Final production batch of 69 from 1990 with a reworked Zaslon after a Phazotron engineer had sold radar details to the West, improved ECM and the R-33S missile.
• MiG-31M (Izdeliye 05): Heavier 1985 development with Zaslon-M, D-30F6M engines and digital flight controls; seven built, never produced in series.
• MiG-31BM: Multirole upgrade of the MiG-31B approved in 2008 with the Baget 55-06 computer, 320 km (200 mi) detection range, R-37 and R-77 compatibility and air-to-surface weapons.
• MiG-31BSM: Parallel upgrade of MiG-31BS airframes from 2014 with a refuelling probe, heat-resistant canopy glass, multifunction displays and a rear-view periscope.
• MiG-31K: MiG-31BM converted to carry one Kh-47M2 Kinzhal, ten by May 2018, with air-to-air equipment removed; the MiG-31I follow-on completed flight tests in April 2024.