* Although the MiG-25 had been a considerable advance in combat aircraft design, it still left something to be desired, and advanced American aircraft were introduced in the 1970s that eroded its edge. As a result, the Soviets developed a substantially improved and more sophisticated derivative of the MiG-25, the "MiG-31", and fielded it in substantial numbers.
* During the 1960s, the West increasingly focused on low-level strike tactics that stood to be highly effective in penetrating Soviet air defenses. In response, the Soviets invested a great deal of effort in building up those defenses. After considering a number of different options, in 1968 work was authorized on a follow-on to the MiG-25 interceptor series.
The improved machine was to provide a general increase in capability and effectiveness over the Foxbat. The Mikoyan OKB considered more radical designs to meet the requirement early on, including swing wing and delta wing configurations, but decided that it would be more effective to retain the basic arrangement of the MiG-25, and give it a thorough workover.
The OKB's investigation led to an order for full development and two prototypes, with the design effort conducted by a team under the Mikoyan OKB's Gleb Lozino-Lozinsky, and the prototypes built in the OKB workshops. The first "Ye-155MP" prototype performed its initial flight on 16 September 1975, with Fedotov at the controls, and the second followed in May 1976.
Viktor Belenko mentioned the new machine during his debriefing by Western intelligence, describing a "Super Foxbat", with two seats, a strengthened fuselage for low-altitude flight, and a powerful look-down / shoot-down radar. Exaggerated details leaked in the Western press led to a best-selling technothriller novel, Craig Thomas's FIREFOX, involving a Soviet super-fighter with Mach 3 performance, vertical takeoff capability, and direct mind control over aircraft systems; the novel led in turn to one of the worst movies Clint Eastwood ever made.
Work on what would become a total of eight preproduction machines began at the factory in Gorky in 1977. In 1978, a US spy satellite observed one of the evaluation machines, flying at 6,000 meters (20,000 feet), intercepting a target drone emulating a cruise missile flying at 60 meters (200 feet) and 20 kilometers (12.5 miles) away. That was impressive, though since the Soviets were perfectly aware of the orbital schedules of American spy satellites, it suggests the whole thing was a staged "photo-opportunity".
Trials continued into 1980, leading to a formal authorization in 1981 of full production of what was originally to be designated the "MiG-25MP" but emerged as the "MiG-31". The type entered front-line PVO service in 1982, replacing the Tu-128 Fiddler. Aircrew were impressed by the MiG-31's sophistication, range, speed, and said it could climb "like a rocket". Like the MiG-25 before it, the MiG-31 was not very maneuverable, but there was really no need for it to be.
NATO assigned the MiG-31 the reporting name "Foxhound". The West finally got good pictures of the MiG-31 in 1985, when a Norwegian pilot intercepted one over the Barents Sea and took some shots of it. That was almost certainly a photo-opportunity, the Soviets having long used such intercepts as a means of unveiling new aircraft to the West, with the aircraft turning back for home the moment the photo session was over.BACK_TO_TOP
* The general configuration of the MiG-31 is similar enough to that of the MiG-25 for the two be confused at a casual glance. They are both slab-sided aircraft with twin engines featuring ramp inlets, a high-mounted swept wing, twin tailfins, and ventral fins. However, any more than a casual glance shows the MiG-31 to be clearly different from the MiG-25.
The first visible difference is that the MiG-31 was built from the start as a two-seat aircraft. The Soviets had finally decided that a completely ground-controlled approach to air defense was too inflexible, and so the MiG-31 was designed to be able to hunt and fight more or less independently, with a back-seater directing the pilot to targets using a much improved sensor suite, and controlling the weapons systems. The USSR did not have a continuous ground-based air-defense barrier such as the US-Canadian DEW line; the MiG-31 could be used to plug the gaps.
The two crew are placed in tandem under individual rear-hinged clamshell canopies, though the design team did consider a side-by-side arrangement as well. The crew sit on Zvezda K-36DM "zero-zero" (zero speed, zero altitude) ejection seats, which have built-in massage pads to keep the crew more comfortable on long patrol missions. The cockpits are painted using a dark turquoise color scheme, often used on Soviet-Russian aircraft, having been judged by Soviet ergonomics experts as relaxing for aircrew. The rear cockpit features a simple set of flight controls and a retractable periscope, to allow the back-seater to get the aircraft home in an emergency, as well as to provide flight training without a specialized trainer variant.
The MiG-31's wing is also noticeably different from the MiG-25's, with leading-edge root extensions with a sweep of 70 degrees and a thinner cross-section. Each wing features four-section leading-edge flaps; two-section trailing-edge slats; and outboard flaperons. The leading-edge flaps deploy automatically at low speeds, and are also used for combat maneuvering. The fuselage and engine inlets were designed to contribute to lift. The redesigned fuselage also features increased fuel capacity. Airbrakes are fitted under the engine inlets and forward of the main gear doors.
The landing gear is new and distinctive as well. The two-wheel nosegear is moved forward relative to the MiG-25, retracting backward instead of forward as on the MiG-25, and the main gear features two wheels, arranged in tandem but offset. This prevents the rear wheel from following in the rut created by the front wheel as it rolls over snow or mud. The MiG-31 uses twin cruciform brake parachutes, stowed in a fairing between and above the engine exhausts.
The Foxhound's primary weapon is the big "R-33" (NATO "AA-9 Amos") SARH AAM, roughly in the same class and strongly resembling the US Hughes AIM-54 Phoenix long-range AAM used on the Grumman F-14 Tomcat. Some sources suggest that the R-33 is actually, to some lesser or greater degree, a copy of the Phoenix, with the design details obtained from samples of the Phoenix obtained from Iran after the Islamic Revolution in that country. The MiG-31 can carry four R-33s in recesses under the fuselage, in an arrangement along the lines of that used by the Tomcat to carry its Phoenix AAMs. An R-33 swings down on a hydraulically actuated trapeze for launch. All four missiles can be launched in salvo, with each seeking out a different target in parallel.
The Foxhound has four underwing pylons, though apparently early machines only had two, which can be used to carry the R-40TM / AA-6 Acrid, R-60M / AA-8 Aphid, or newer "R-77" ("AMRAAMski / NATO AA-12 Adder") missiles. Typical warload is four R-33s under the fuselage and two or four R-60s on the underwing pylons, or three R-33s under the fuselage, the fourth position being taken up by a controller pod for two underwing R-40s.
A 2,500-liter (660-US gallon) external tank can be mounted under each outboard pylon. The MiG-31 actually has gun armament, consisting of a GSh-6-23 six-barreled 23-millimeter Gatling-type cannon mounted in a fairing set well back on the belly of the aircraft, just behind the right main landing gear door. The cannon has a rate of fire from 6,000 to 8,000 rounds per minute, and the MiG-31 carries an ammunition store of 260 rounds.
The airframe features more titanium and aluminum alloy than the MiG-25. The MiG-31 is powered by two Aviadvigatel D-30-F6 bypass turbojets, with an impressive afterburning thrust of 152 kN (15,500 kgp / 34,175 lbf) each, as well as fuel economy unimaginable with the old RB-15 engines. The engine intakes, which were the focus of considerable design effort to ensure better efficiency, feature an upper moving inlet ramp and a lower moving inlet lip. There are auxiliary inlet doors on top of the intakes.
* Avionics were significantly improved. The main sensor is the SBI-16 (S-800) "Zaslon" ("Shield" / NATO "Flash Dance") phased-array / electronically steered radar, the first such type of system to reach first-line service in a Soviet fighter, with 120 degrees coverage; excellent look-down / shoot-down capabilities; maximum detection range of 200 kilometers (125 miles); and maximum tracking range of 120 kilometers (75 miles). The radar can track ten targets and engage four of them at one time, with the targets prioritized by the interceptor's mission computer. A semi-retractable TP-8 IRST is also fitted as a passive sensor. Both are linked into an Argon-15 digital fire-control computer.
Although the MiG-31 is capable of autonomous operation, the Soviets did not abandon their ground-control network by any means, and the Foxhound can be directed semi-automatically by the AK-RLDN ground-based automatic guidance network, using the aircraft's APD-518 digital datalink and BAN-75 command link. The datalink can also be used to hook up the fighter to an Ilyushin A-50 "Mainstay" airborne warning and control system (AWACS) aircraft, as well as allow "wolfpacks" of four MiG-31s to cooperate under the control of a flight leader, covering a swath of airspace 900 kilometers (560 kilometers) wide. The flight leader can direct his three wingmates to specific targets.
The MiG-31 features other improved avionics, including updated radios; IFF; RWR; and particularly an NK-25 navigation system, featuring receivers for the Tropik medium-range radio navigation system, similar to the US LORAN, and the Marshrut long-range radio navigation system, similar to the US Omega. One of the motivations for such extensive navigation gear was to allow the Foxhound to patrol deep into Arctic airspace in search of Western cruise-missile carrier aircraft. Trial flights included such deep-arctic sorties, including one that overflew the North Pole.
MIKOYAN MIG-31 INTERCEPTOR ("FOXHOUND"): _____________________ _________________ _______________________ spec metric english _____________________ _________________ _______________________ wingspan 13.46 meters 44 feet 4 inches wing area 61.6 sq_meters 663 sq_feet length 22.69 meters 74 feet 6 inches height 6.2 meters 20 feet 4 inches empty weight 21,825 kilograms 48,115 pounds normal weight 41,000 kilograms 90,388 pounds MTO weight 46,200 kilograms 101,851 pounds max speed at altitude 3,000 KPH 1,865 MPH / 1,620 KT service ceiling 20,600 meters 67,585 feet take-off run 1,200 meters 3,940 feet ferry range 3,300 kilometers 2,050 MI / 1,780 NMI operational radius 1,200 kilometers 745 MI / 648 NMI _____________________ _________________ _______________________
The MiG-31 proved to be highly satisfactory in operational service; field commanders began to consider it for other missions, such as escort of long-range maritime patrol aircraft. That strained the range of the Foxhound, and so the MiG OKB designed a semi-retractable flight refueling probe that was fitted to the left side of the nose. The probe was introduced into standard production.
* In 1985, Soviet security arrested Adolf Tolkachev, head of the Phazotron radar design bureau, for selling secrets to the West. Tolkachev had compromised the radar systems of most of the USSR's first-line combat aircraft. The Soviets took a very dim view of traitors and Tolkachev was executed, but the damage had been done: the MiG-31's radar had been compromised, allowing it to be neutralized through countermeasures. The MiG OKB had already been working on improvements to the Foxhound, and came up with a new Foxhound variant, the "MiG-31B", which featured a new Zaslon radar with improved range and counter-countermeasures; as well as other updated avionics, including modernized digital processors; plus support for the improved R-33S AAM and fit of the inflight refueling probe as standard.
The MiG-31B entered production in 1990. The Gorkiy factory updated many early-production MiG-31s to the same standard, with these machines receiving the designation "MiG-31BS".BACK_TO_TOP
* A total of about 500 MiG-31s was built by the factory at Gorkiy up to the fall of the USSR. There were several minor and proposed Foxhound modifications and variants:
* In the mid-1980s, the MiG OKB began work on an improved interceptor variant, the "MiG-31M", which was primarily designed as a carrier for the R-37 AAM, an improved follow-on to the R-33 with an astounding range of 300 kilometers (186 miles). Seven MiG-31M prototypes were built, with the first flying in late 1985.
An improved Zaslon-M radar was fitted, along with a new IRST featuring a laser rangefinder. A new "fat" spine was fitted to the aircraft to accommodate improved avionics and increase fuel storage. At least one prototype featured wingtip pods with vertical fins for electronic systems. Large LERXes were fitted to improve high angle of attack handling; the tailfins and ventral fins were reconfigured to a degree; and an improved inflight refueling probe was designed, to be fitted to the right side of the nose of the aircraft.
Six R-39s could be carried under the fuselage in recesses, arranged as three rows of two missiles. All six could be launched in salvo and seek different targets. Four R-77 AAMs could also be carried on underwing pylons. The cannon was deleted. The cockpit was redesigned, with the front seater getting a new single-piece windscreen, and the windows for the back-seater reduced to a small panel on either side to allow him to focus his attention on his displays. Back-seat flight controls were deleted.
* The MiG-31M did not enter production since the Russian state lacked the money to buy many new aircraft, and so in 1997 the MiG organization began work on a multi-role upgrade to existing MiG-31s, designated "MiG-31BM".
A MiG-31BM prototype was demonstrated publicly in 1999. It featured an updated Zaslon radar close to Zaslon-M standards; a satellite navigation receiver; and significantly upgraded cockpit arrangements, with the back-seater provided with three large flat-panel displays. It is unclear if the cockpit arrangements were inherited from the MiG-31M or, as would seem likely given technological advances since the 1980s, used more advanced systems. The MiG-31BM could carry six R-33S or R-37 AAMs, as well as underwing stores such as smaller AAMs, ARMs, or iron bombs.
The program moved along slowly, but by late 2006 the Russian Air Force (which absorbed the disbanded PVO after the fall of the USSR) was performing flight trials on two MiG-31BMs. In 2011, the service committed to upgrading 60 machines by 2020. There's talk of a replacement for the MiG-31, tagged as the "PAK-DP", but development isn't planned to start until late in the decade.BACK_TO_TOP
* MiG-25 variants include:
_________________________________________________________________________ INTERCEPTOR & SEAD VARIANTS: Ye-155P Prototypes. MiG-25P Foxbat-A Initial production interceptor with Smerch radar. MiG-25PD Foxbat-E Improved interceptor with Saphir radar. MiG-25PDS Foxbat-E MiG-25Ps upgraded to MiG-25PD spec. MiG-25BM Foxbat-F Dedicated SEAD variant. RECONNAISSANCE VARIANTS: Ye-155R Prototypes. MiG-25R Foxbat-B Initial photo-reconnaissance variant. MiG-25RB Foxbat-B Improved MiG-25R with bombing capability. MiG-25RBV Foxbat-B Updated MiG-25RB. MiG-25RBT Foxbat-B Further updated MiG-25RB. MiG-25RBK Foxbat-D Dedicated ELINT variant. MiG-25RBF Foxbat-D Improved MiG-25RBK. MiG-25RBS Foxbat-D Dedicated SLAR (imaging radar) variant. MiG-25RBSh Foxbat-D Improved MiG-25RBS. TRAINERS: MiG-25PU Foxbat-C Two-seat interceptor trainer. MiG-25RU Foxbat-C Two-seat reconnaissance trainer. MISCELLANEOUS VARIANTS: Ye-266 Cover designation for record-setting prototypes. Ye-133 Cover designation for record-setting MiG-25PU. X-500 Cover designation for "Egyptian" MiG-25Rs. I-99 Two test machines for D30F engines. MiG-25PDS Prototype interceptor with improved ECM. MiG-25PDZ MiG-25P fitted with refueling probe. MiG-25M (Ye-266M) Two test machines for improved RB15 engines. MiG-25PU-SOTN Trainer modified for Buran shuttle program. MiG-25MR MiG-25RBs modified for weather reconnaissance. MiG-25RBVDZ MiG-25RBV fitted with refueling probe. MiG-25RBShDZ MiG-25RBSh fitted with refueling probe. MiG-25RBN Prototype night reconnaissance machine. MiG-25RR Eight MiG-25RBVs modified for fallout sampling. _________________________________________________________________________
* MiG-31 Foxhound variants include:
_________________________________________________________________________ MiG-31 Initial production version. MiG-31B Later production version with updated radar. MiG-31BS Initial production upgraded to MiG-31B spec. MiG-31LL One early MiG-31 used for tests. MiG-31D Two prototypes of an ASAT system. MiG-31A Proposed smallsat launcher using MiG-31D. MiG-31F Proposed multi-role version. MiG-31E Proposed export versions. MiG-31M Next-generation Foxhound, 7 prototypes built. MiG-31BM Upgraded MiG-31B with MiG-31M features. _________________________________________________________________________BACK_TO_TOP
* I thought that writing up the MiG-25 and MiG-31 would be a straightforward exercise. I wasn't thinking. It turned out to be much more work than I expected: as with most Soviet-Russian aircraft, different sources on the MiG-25 tend to give frustratingly different stories, particularly in terms of variant descriptions and designations.
I remember from when I was a kid back in the 1960s how impressive the Foxbat seemed in the West. It is a bit surprising to look back from the 21st century and find that it has something of an outdated "boilerplate" appearance, and that the type has been, if not precisely forgotten, at least neglected. Information on it, particularly good information, tends to be hard to come by.
* As concerns copyrights and permissions for this document, all illustrations and images credited to me are public domain. I reserve all rights to my writings. However, if anyone does want to make use of my writings, just contact me, and we can chat about it. I'm lenient in giving permissions, usually on the basis of being properly credited.
* Sources include:
* Revision history:
v1.0.0 / 01 nov 03 v1.0.1 / 01 sep 05 / Review & polish. v1.0.2 / 01 may 07 / Review & polish. v1.0.3 / 01 apr 09 / Review & polish. v1.0.4 / 01 mar 11 / Review & polish. v1.0.5 / 01 feb 13 / Review & polish. v1.0.6 / 01 jul 14 / Review & polish. v1.1.0 / 01 jun 16 / Moved comments on Belenko around.BACK_TO_TOP