Mikoyan MiG-31 - Development

Development

The MiG-25, despite Western panic about its tremendous performance, made substantial design sacrifices in capability for the sake of achieving high speed, altitude, and rate of climb. It lacked maneuverability at interception speeds, was difficult to fly at low altitudes, and its inefficient turbojet engines resulted in a short combat range at supersonic speeds. The MiG-25's speed was limited to Mach 2.83 in operations, but it could reach a maximum speed of Mach 3.2 with the risk of damaging the engines beyond repair.

Development of the MiG-25's replacement began with the Ye-155MP (Russian: Е-155МП) prototype which first flew on 16 September 1975. Although it bore a superficial resemblance to a stretched MiG-25 with a longer fuselage for the radar operator cockpit, it was in many respects a new design. The MiG-25 used 80% nickel steel in its structure to allow welding. The Ye-155MP doubled the use of titanium to 16% and tripled the aluminium content to 33% to reduce structural mass. More importantly, supersonic speed was now possible at low altitudes. Fuel capacity was also increased, and new, more efficient low bypass ratio turbofan engines were fitted.

The most important development was introducing an advanced radar capable of both look-up and look-down engagement (locating targets above and below the aircraft), as well as multiple target tracking. This finally gave the Soviets an interceptor able to engage the most likely Western intruders at long range. It also reflected a policy shift from reliance on ground-controlled interception (GCI) to greater autonomy for flight crews.

Like its MiG-25 predecessor, the MiG-31 was surrounded by early speculation and misinformation concerning its design and abilities. The West learned of the new interceptor from Lieutenant Viktor Belenko, a pilot who defected to Japan in 1976 with his MiG-25P. Belenko described an upcoming "Super Foxbat" with two seats and an ability to intercept cruise missiles. According to his testimony, the new interceptor was to have air intakes similar to the Mikoyan-Gurevich MiG-23, which the MiG-31 does not have, at least not in production variants. While the MiG-31 was undergoing testing, an unknown aircraft was spotted by a reconnaissance satellite at the Zhukovsky flight test center near the town of Ramenskoye. The images were interpreted as a fixed-wing interceptor version of a swing-wing fighter codenamed "Ram-K". The latter was eventually revealed to be the Sukhoi Su-27 'Flanker', a wholly unrelated design.

Series production of the MiG-31 began in 1979 and about 400 were produced by 2000.

Some upgrade programs have found their way in the MiG-31 fleet, like the MiG-31BM multirole version with upgraded avionics, new multimode radar, hands-on-throttle-and-stick (HOTAS) controls, liquid crystal (LCD) color multi-function displays (MFDs), ability to carry the Vympel R-77 missile and various Russian air-to-ground missiles (AGMs) such as the Kh-31 anti-radiation missile (ARM), a new and more powerful computer, and digital data links. A project to upgrade the Russian MiG-31 fleet to the MiG-31BM standard was begun in 2010; 60 or more aircraft are to be upgraded to MiG-31BM standard by 2020.