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MiG-25 Origins
In the late 1950s, the Soviet Union became aware of a trio of new extremely-high-speed American aircraft under development- the B-58, A-12, and B-70. Soviet interceptors then in service would be entirely inadequate to intercept these new threats. So in 1958 Mikoyan was tasked with developing a supersonic multirole aircraft to serve both as an interceptor and a high-altitude high-speed reconnaissance aircraft. Mikoyan at the time was developing an aircraft designated the Ye-150, a single-seat single-engine high-speed interceptor. However, it was clear that the Ye-150 and its derivatives would fall short of the required performance, particularly speed, and a more powerful design was needed. This would be the Ye-155, a twin-engine aircraft based on the Ye-150 but with a radically different design, possibly incorporating design elements stolen from the American A3J Vigilante. Perhaps most notably the Ye-155 would switch from the annular nose intake reminiscent of the MiG-21 to a pair of fuselage side intakes.
In February 1961 the Ye-155 was given the go-ahead for further development in the Ye-155P interceptor and Ye-155R recon variants. These would be largely identical, differing primarily in avionics. The greatest challenge facing the Ye-155 was finding a powerplant powerful enough to push the aircraft to its required Mach 3 top speed. Fortunately, there was already one such engine- the R-15 developed for the Tu-121 cruise missile and used in the Tu-123 reconnaissance drone. However, the R-15 had one major issue. Designed for cruise missiles it greatly prioritized thrust over service life. While modifications to the compressor, combustion chamber, and afterburner would greatly extend the life of the engines they would remain a major issue for the reliability of the MiG-25 family.
Presented with the issue of extreme kinetic heating at top speed, Mikoyan was faced with a choice- attempt to develop new heat-resistant alloys, or use cheap stainless steel. They chose the latter. The Ye-155 would be 80% stainless steel by weight. To protect internal systems from heating, it would utilized nitrogenated fuel and feature massive cooling and air conditioning systems, as well as reflective anti-heating paint. Overall this resulted in a relatively cheap and conventional aircraft, but an extremely high empty weight of approximately 20 tonnes, over three times that of the MiG-21.
The Ye-150 was the predecessor of the MiG-25
During early development of the Ye-155 several other unusual configurations were considered, including the use of lift-jets and swing-wings
The Ye-155R and MiG-25R
The first Ye-155R prototype, Ye-155R-1, was completed in December 1963. It lacked avionics and had a number of unique features that wouldn’t be incorporated on later aircraft: optional canards for high-speed handling, large wingtip fuel tanks to reduce flutter, downwards wingtip fins, and a double-curved nose cone. The aircraft would make its first flight on 6th March 1964. The aircraft performed well at subsonic speeds despite its weight, but would roll uncontrollably at transonic speeds. The wingtip tanks, designed to reduce flutter, would actually induce vibrations as their contents were expended. Finally, the aircraft had a whole host of stability, reliability, and heating issues at maximum speed.
Ye-155R-2 was completed in early 1965. Unlike the Ye-155R-1 it lacked wingtip tanks and fins.
Starting in 1966 these two prototypes were supplemented by pre-production aircraft Ye-155R-3 through R-6. These were functionally prototypes, only called “pre-production” as they were produced at the Gorkiy Aviation Plant rather than Mikoyan’s own facilities which were occupied with the production of the MiG-23’s prototypes at the time. These aircraft also had a full avionics fit.
All six aircraft participated in State Acceptance Trials, where camera resolution was of particular significance- at the speeds and altitudes the Ye-155R was designed for any number of problems could reduce image quality. The Ye-155R passed with flying colours; at an altitude of 20km altitude and Mach 2.35 the resolution of its most powerful A-72 camera was a mere 30cm! More troubled was the Peleng-S navigation system, which never achieved acceptable reliability during testing. However, the need for a high-speed reconnaissance aircraft was so great that in late 1969 the Ye-155R-4 standard was officially accepted for production as the MiG-25R with fixes to the Peleng to come on later models.
The first production MiG-25R was completed in 1969. They featured an suite of four A-70M and one A/E-10. Other avionics included the Peleng-S or later Peleng-D navigation suite, the SRO-2P IFF, SPO-10 Sirena-3M RWR, and SPS-141 jammer. However, MiG-25R production was short-lived and all would be soon upgraded to the next standard: the MiG-25RB.
The original Ye-155R-1 prototype was quite different from the production standard
Production MiG-25Rs had a much simpler, cleaner design
Finally, the MiG-25RB
Following the defeat in the Six-Day War in 1967, Egypt requested assistance from the Soviet Union in the form of advanced interceptors, reconnaissance aircraft, and bombers. The MiG-25P and R already covered two of these roles, so it was logical to develop a version to do the third, especially as the MiG-25R was already wired for illumination bombs meaning it would be a simple change to allow carriage of live weapons. In late 1969, Mikoyan was officially tasked with converting the MiG-25R into a dual-role recon-bomber aircraft. The navigation equipment was upgraded, an automatic bombing system was developed, and new high-temperature bomb racks were created. By February 1970, Ye-155R-4 was ready for conversion into the first MiG-25RB prototype.
Issues arose almost immediately. The kinetic heating of high-speed flight proved to be more significant than expected, causing soldering to melt and on several occasions the bomb release pyrotechnics to overheat and detonate, dropping the suspended load. As an interim solution, the bomb racks were relocated from under the wing to under the fuselage, reducing heating. Later, high-temperature racks would be developed which allowed the reintroduction of wing bombs. Accuracy of initial models also suffered; at a standard drop conditions of 23km altitude and 2,500km/h CEP was a whopping 1km- not ideal for mere 500kg bombs. This would be reduced by an order of magnitude with the introduction of the Peleng-D navigation suite with a much more precise complement of float gyros for INS, as well as a vertical accelerometer and the new Polyot-1I SHORAN. Production of the MiG-25RB started in late 1970 with the type entering service in December that year. The MiG-25RB retained all the capabilities of the MiG-25R.
Ye-155R-4, converted to the prototype of the MiG-25RB
The FAB-500M-62T was an insulated version of the FAB-500M-62 developed specifically for the MiG-25RB to allow longer top-speed “sprints” without risking damage to the bomb’s fuze
Bombat in Service
The Middle East would be the testing ground for the MiG-25. The Soviets recognized the growing tension in the Middle East, which would serve as the ideal combat test for the MiG-25 to prove that its size and cost were worth its performance. To this end, two each MiG-25Rs and MiG-25RBs were shipped to Egypt in March 1971, to be piloted by experienced Soviet pilots in Egyptian uniforms. The Soviets attempted to keep the MiGs’ presence secret, with little success.
Starting in May, the four aircraft would be used in flights over Israel. Israeli attempts to down the MiGs were fruitless; nothing could catch a Foxbat. They flew above the maximum altitude of the MIM-23 Hawk and far faster than the F-4E Kurnass could manage. In theory, the F-4E could catch the MiG-25 head-on and destroy it with an AIM-7, but this required perfect positioning and timing. Only once did an Israeli Phantom manage to lock a MiG-25, on 16th May 1972, but its AIM-7E lacked the energy to catch the Foxbat and would instead eventually fall mostly intact onto Egyptian soil, being handed off to the Soviets. It was during one of these reconnaissance flights that a MiG-25 was reportedly tracked by Israeli radar at a speed of Mach 3.2, with Soviet records indicating the aircraft reached 3,400km/h. In July 1972, deteriorating Soviet-Egyptian relations resulted in an the expulsion of the Soviet military mission. Soviet MiG-25RBs would return in 1973 during the Yom Kippur War, but by the conflict’s end only one had been reassembled (the MiGs were shipped disassembled, being too large to fit in an An-22). This second deployment would remain in Egypt until late 1974.
From 1971, the MiG-25RBs were deployed across the Soviet Union as well as in Poland and East Germany, performing regular reconnaissance missions, though without any particular operations of note.
Following Belenko’s infamous 1976 defection, the MiG-25’s technology was no longer a closely-kept secret. So, both interceptor and recon-bomber versions were offered for export to a variety of nations, with their service in the Iran-Iraq war and Gulf War being of particular note. However, by this point the original MiG-25RB had been replaced by upgraded models including for export, so I won’t go any further here.
MiG-25RB over Cairo. Note the dappled camouflage
MiG-25RBs at Werneuchen, East Germany, one of the main forward deployment locations of the MiG-25
Further Developments
The MiG-25RB was just the first in a long line of recon-bomber MiG-25s, with most later versions differing only in avionics:
- MiG-25RBK, with Koob-3 SIGNIT suite, later refit with SPO-15
- MiG-25RBK, export model of above but with downgraded avionics
- MiG-25RBS, with synthetic-aperture Sablya-E SLAR instead of cameras
- MiG-25RBV, with SRS-9 Virazh SIGNIT suite
- MiG-25RBN, with NAFA-MK-75 night cameras
- MiG-25RBT, with Tangazh SIGNIT suite and SPO-15
- MiG-25RBSh, MLU for the RBS, with new Shompol SLAR
- MiG-25RBF, MLU for the RBK, with new Shar-25 SIGNIT
However, the MiG-25RB was also the basis for a number of more specialized aircraft:
- MiG-25MR, a weather aircraft
- MiG-25RR, radiation reconnaissance aircraft for detecting and monitoring nuclear tests
- MiG-25BM, SEAD aircraft with Kh-58Us and SPO-15, but no countermeasures
- MiG-25RU twin-seat trainer
This was in addition to a number of testbeds, prototypes, and projects.
The last MiG-25RB variant was the MiG-25BM armed with Kh-58U ARMs
Both interceptor and bomber MiG-25s were used by the Buran program as testbeds. The MiG-25 was the closest thing to a spaceplane available at the time!
