• The MiG-25 was designed to counter the Mach 3 XB-70 Valkyrie and has the ability to reach Mach 2.8+.

The Mikoyan-Gurevich MiG-25 (NATO reporting name "Foxbat") was a super fast interceptor and reconnaissance/bomber aircraft (its speeds are still not matched today!) designed by the Soviet Union's Mikoyan-Gurevich bureau. First flown as a prototype in 1964, it entered service in 1970. With a top speed of Mach 3.2(however the engines would blow up at that speed), a powerful radar and four air-to-air missiles, the MiG-25 worried Western observers and prompted development of the F-15 Eagle.

The aircraft's true capabilities were not discovered until 1976 when Viktor Belenko, a Soviet MiG-25 pilot, defected to Japan. Subsequent analysis revealed a simple-yet-functional design with vacuum-tube electronics, two massive turbojet engines, and sparing use of advanced materials such as titanium. The MiG-25 series had a production run of 1,190 aircraft. The MiG-25 flew with a number of Soviet allies and former Soviet republics and it remains in limited service in Russia and several other nations.

The MiG-25 'Foxbat', 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 thirsty turbojet engines resulted in a very short combat range at supersonic speeds. The MiG-25's speed gauge was redlined at Mach 2.8, and pilots were instructed not to top Mach 2.5 in order to preserve the engines. Achieving the MiG-25's maximum speed of Mach 3.2 would result in the destruction of the engines.

The MiG-25's radar was also powerful enough to burn through the electronic countermeasures (ECM) of enemy aircraft.[citation needed] The radar's power system operated on vacuum tubes, which may seem odd to Western observers, but their use was very practical for the Soviets and served them well, including reduced susceptibility to damage from the electromagnetic pulses generated by nuclear explosions. Nonetheless, the Foxbat proved to be more useful in the reconnaissance role than as an interceptor.

A true understanding of the strengths and failings of the MiG-25 by the West came in 1976. On 6 September, a PVO pilot, Lt. Viktor Belenko, defected to the West, landing his MiG-25P at Hakodate Airport in Japan. It was carefully dismantled and analyzed by the Foreign Technology Division (now the National Air and Space Intelligence Center) of the United States Air Force, at the Wright-Patterson Air Force Base near Dayton, Ohio. After 67 days, the aircraft was returned to the Soviets in pieces. The analysis showed some surprising facts:

* Belenko's particular aircraft was brand new, representing the very latest Soviet technology.

* The aircraft was assembled very quickly, and was essentially built around its massive Tumansky R-15(B) turbojets.

* Welding was done by hand and construction was relatively crude. As in many Soviet aircraft, rivet heads were left exposed in areas that would not adversely affect aerodynamic drag.

* The aircraft was built of a nickel-steel alloy and not titanium as was assumed (though some titanium was used in heat-critical areas). The steel construction contributed to the craft's massive 64,000 lb (29,000 kg) unarmed weight.

* The majority of the on-board avionics were based on vacuum-tube technology, not solid-state electronics. Seemingly obsolete, vacuum tubes were actually more tolerant of temperature extremes, thereby removing the need for providing complex environmental controls inside the avionics bays. In addition, the vacuum tubes were easy to replace in remote northern airfields where sophisticated transistor parts may not have been readily available. As with most Soviet aircraft, the MiG-25 was designed to be as rugged as possible. Also, the use of vacuum tubes makes the aircraft's systems more resistant to an electromagnetic pulse, for example after a nuclear blast.

* Thanks to the use of vacuum tubes, the MiG-25P's original Smerch-A (Tornado, NATO reporting name 'Foxfire') radar had enormous power %u2014 about 600 kilowatts.

* The airspeed indicator was redlined at Mach 2.8, with typical intercept speeds near Mach 2.5 in order to extend the service life of the engines. An Egyptian MiG-25 was tracked flying over Israel at Mach 3.2 in 1973, but the flight had resulted in the destruction of its engines.[6]

* Maximum acceleration (g-load) rating was just 2.2 g (21.6 m/s²) with full fuel tanks, with an absolute limit of 4.5 g (44.1 m/s²). One MiG-25 withstood an inadvertent 11.5 g (112.8 m/s²) pull during low-altitude dogfight training, but the resulting deformation decommissioned the airframe.

* Combat radius was 186 miles (300 km), and maximum range on internal fuel (at subsonic speeds) was only 744 miles (1,200 km). In fact, Belenko had only just made it to Japan without running out of fuel %u2014 without sufficient fuel for a carefully planned landing, he narrowly missed a commercial airliner taking off, and overran the available runway on landing.

As the result of Belenko's defection and the compromise of the MiG-25P's radar and missile systems, beginning in 1978 the Soviets developed an advanced version, the MiG-25PD ('Foxbat-E'), with a new RP-25 Saphir look-down/shoot-down radar, infrared search and track (IRST) system, and more powerful engines. About 370 earlier MiG-25Ps were converted to this standard and redesignated MiG-25PDS.

About 1,186 MiG-25s were produced before production ended in 1984, and the type was exported to Algeria, Bulgaria (3 MiG-25R and 1 MiG-25RU until 1992), India (until 2006), Iraq, Libya, and Syria. Modest numbers remain in service.

The development of the MiG-25 began in the 1950s, paralleling American efforts to develop a Mach 3 bomber and interceptor aircraft, including the experimental XB-70 Valkyrie, the XF-103 Thunderwarrior, the Lockheed YF-12, and the XF-108 Rapier. With the first Mach 2 aircraft beginning to enter service, Mach 3 seemed like the next logical step. A variety of roles were considered, including cruise missile carriers, and even a small five to seven passenger supersonic transport, but the main impetus was a new high-altitude reconnaissance aircraft and heavy interceptor. If a Mach 3 bomber were to enter American service, it would have been nearly invulnerable to Soviet air defense.[citation needed]

The Mikoyan-Gurevich OKB accepted the assignment effective 10 March 1961, carrying the bureau designation "Ye-155" (or "%u0415-155"). Although the XB-70 Valkyrie was cancelled before the new Soviet aircraft reached the prototype stage, it seemed that the Ye-155 would still be a useful addition to the PVO Strany air defense interceptor force for use against reconnaissance targets like the SR-71 Blackbird.

Because of the thermal stresses incurred in flight above Mach 2, the MiG-25 could not be constructed with traditional aluminium alloys. Lockheed had utilized titanium for their YF-12 and SR-71 series aircraft and North American used a honeycombed steel material for the XB-70. Both American companies struggled with the materials used to construct their respective aircraft. In the end, Mikoyan-Gurevich OKB constructed the MiG-25 largely from nickel alloy ("Inconel") steel. The steel components of the MiG-25 were formed by a combination of spot-welding, automatic machine welding and hand arc welding methods. Initially there was concern that the metal welds would crack when the aircraft experienced the normal jolting of a landing. This did not prove to be the case, and any cracks that developed in service were easily welded in the field. A small amount of titanium and aluminum alloys were also used in the construction of the MiG-25, in areas particularly susceptible to high aerodynamic drag.

The first prototype, which was a reconnaissance variant, designated "Ye-155-R1" by the bureau, made its first flight on 6 March 1964. The prototype interceptor, "Ye-155-P1", took to the air on 9 September 1964. Development, which represented a major step forward in Soviet aerodynamics, engineering and metallurgy, took several more years to complete. In the meantime, several prototypes, under the cover designation "Ye-266" (or "%u0415-266"), made a series of record-setting flights in 1965, 1966, and 1967. Series production of the two initial variants, designated MiG-25P ('Foxbat-A') (interceptor) and MiG-25R ('Foxbat-B') (reconnaissance), began in 1969. The MiG-25R entered Soviet Air Force (VVS) service almost immediately, but the service entry of the MiG-25P with the PVO was delayed until 1972. A non-combat trainer variant was also developed for each version, the MiG-25PU ('Foxbat-C') and MiG-25RU, respectively. The MiG-25R evolved several subsequent derivatives, including the MiG-25RB reconnaissance-bomber, the MiG-25RBS and MiG-25RBSh with side-looking airborne radar (SLAR), the MiG-25RBK and MiG-25RBF ELINT aircraft ('Foxbat-D'), and the MiG-25BM ('Foxbat-F') SEAD variant, carrying four Raduga Kh-58 (NATO reporting name AS-11 'Kilter') anti-radiation missiles.

The MiG-25 was capable of high performance, including a maximum speed of Mach 3.2 and a ceiling of 90,000 ft (27,000 m), although on Aug. 31, 1977, an E-266M, a specially modified Foxbat, flown by MiG OKB Chief Test Pilot Alexander Fedotov, set the recognized absolute altitude record for a jet aircraft under its own power, reaching 123,523.58 ft (37,650 m) at Podmoskovnoye, USSR in a brief zoom climb. The record is the only recognized absolute record not held by a pilot from the United States.Although intended for intercepting or threatening high-altitude, high-speed aircraft the MiG-25's maneuverability, range, and close combat potential were extremely limited. Even its tremendous speed was problematic: although the available thrust was sufficient to reach Mach 3.2, a limit of Mach 2.8 had to be imposed to prevent supposed total destruction of the engines,though whether this was inevitable is disputed.Mach 2.5 and greater was difficult to reach without overspeeding the turbines.

Despite these limitations, inaccurate intelligence analysis and several false assumptions caused a panic in the West, where it was initially believed that the MiG-25 was actually an agile air-combat fighter rather than a stand-off interceptor. In response, the United States launched an ambitious new program, which resulted in the McDonnell-Douglas F-15 Eagle.