In 1966, the Mikoyan Design Bureau launched the development of the E-155M multi-purpose variable-geometry twin-seater powered by two RD36-41M turbo-jet engines designed by the OKB-36 MAP Design Bureau (Chief Designer Pyotr Kolesov). It derived from the E-158 interceptor (1965), which was a further development of the E-155P
(MiG-25P) swing-wing aircraft powered by RD-19M engines. In accordance with the 24 May, 1968 directive by the USSR Council of Ministers, there were three E-155M versions to be developed - the E-155MP fighter-interceptor as part of the S-155M airborne all-altitude interceptor, the
E-155MF tactical missile-carrying bomber as well as the E-155MR reconnaissance aircraft. For the first time in the world practice, the Zaslon phased array radar capable of detecting all types of aerial targets at long ranges within the whole scope of altitudes and speeds including treetop targets flying against the land background, was supposed to become the backbone of the E-155MP's armament control system.
The radar featured the beam electronic scanning capability, which provided the view of a wide solid angle and made it possible to rid of the low-speed mechanical antenna drives and solve the problem of tracking and attacking a large number of targets without angle limitation.
The E-155MP (518-21) conceptual design was tailored in 1968. The directive required that the aircraft proceed to a joint state testing in the fourth quarter of 1971, however, further research found it necessary to re-design the aircraft configuration - the existing configuration provided lower climb rate and service ceiling if compared to the characteristics set, with the design proper being too heavy. In 1969, the development of the E-155MP modified design was commenced (product 518-22). In 1971, the aircraft configuration with a fixed trapezoid wing, conformal under-fuselage K-33 missile attachment and tandem-type two-seat cockpit to house the pilot and the systems operator was finally approved. The aircraft was supposed to be powered by the D-30F-6 engines designed by the Perm-based MKB Design Bureau (Chief Designer Pavel Solovyev).
One of the new requirements to meet was the capability to engage in semi-self-sustained combat without the continuous radar AD coverage in the country's Far North and Far East. That led to the development of the E-155MP (product 83) fighter-interceptor predesign in 1972.
The construction of the first E-155MP experimental aircraft (product 83/1, side number 831) was finished in 1975 at the Moscow-based Mikoyan Machine-building Plant (Russian abbreviation MMZ). Already at that time, the aircraft was equipped with the D-30F-6 issue engines. Initially, the version had the MiG-25RB wing (without leading edge slats and extensions but with sharp leading edges), which in the course of the testing was replaced by a new one with LERXes, leading edge slats, drooping ailerons and flaps. The differential stabilizer with a swept rotation axis featured a five-degree trailing edge bent-up trim strip. The under-fuselage fins' area was increased by 1.2 sq.m if compared with the MiG-25. The brake-flaps or flaps of the main gear, featuring an original two-wheel bogie design moved in the plane set at an angle of 40 degrees with the aircraft symmetry plane. The wing fuel tanks were not connected with the fuel system.
The aircraft housed the Polyot-1I navigation system and the SAU-155UP automatic control system. There were overall and weight mock-ups instead of the issue Zaslon radar and infrared sensor. Both cockpits accommodated the KM-1M ejection seats. Aircraft #831 made its maiden flight on 16 September, 1975 operated by test-pilot Aleksandr Fedotov. In spring 1976, all Mikoyan pilots tried out the aircraft (Boris Orlov, Aviard Fastovets, Pyotr Ostapenko, Valery Menitsky). Valery Zaitsev was appointed the first navigator-operator.
In early 1976, Mikoyan finished the construction of the second E-155MP aircraft (product 83/2, side number 832). Unlike the first prototype, aircraft #832 housed a complete set of equipment including the Zaslon radar and IR sensor. It also had smaller area under-fuselage fins. On 22 April 1976, Aleksandr Fedotov flew the aircraft for the first time. Aircraft # 831 and 832 participated in stage A of the Joint official testing.
In summer 1977, the Gorky based aircraft production plant built two first MiG-31s of the first development batch coded «Product 01» (registration numbers 011 and 012). They had a number of design features different from experimental aircraft #831 and 832:
For the first time, aircraft #011 flew on 13 July, 1977, and aircraft #012 made its maiden flight on 30 June, 1977. In May 1977, the Joint official testing was launched, with new aircraft of the development batches joining it as the pre-production series (#201 in 1977, #202, 203, 301, 302, and 303 in 1978). Stage A of the Joint official testing finished in December 1978, and there was a preliminary decision taken to initiate the MiG-31 series production that began at the Nizhny Novgorod-based Sokol Aircraft Plant (NGAZ) in 1979.
That very year, in Gorky (Nizhny Novgorod), there was an aircraft built (#305) for the first time equipped with the K-36DM standard ejection seats. In the course of the MiG-31 testing, there were flying laboratories (FL) widely used, which were derived from other aircraft - two Tu-104 FLs (1970 and 1972) to test the Zaslon radar, the MiG-21 FL (1970) to test the K-33 missile systems, the MiG-25P-10 FL (1973) to check the K-33 missile catapult start, the MiG-25PU (1975) to test the SAU-155MP automatic control system and the KN-25 navigation system, the MiG-25RB FL (product 99, 1976) to test and operationally develop the D-30F-6 engines. Stage B of the Joint official testing began in September 1979 and finished in September 1980 when for the first time the series aircraft were deployed with AD Forces line units. In accordance with a directive of the USSR Council of Ministers dated 6 May 1981, the MiG-31 interceptor boasting the RP-31 radar and R-33 missiles entered the inventory.
The production modification of MiG -31B was equipped with in-flight refuelling system. In 1985-86 the new versions of an airplane - interceptor MiG-31M and ASAT MiG-31D, and in 1998 multi-purpose MiG-31BM have appeared.
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