Only few and rather corny information leaked into the West, and the 301 was believed not only to act as a reconnaissance plane , it was also believed to have (nuclear) bombing capabilities. Despite wind tunnel testing with models, no hardware of the 301 was ever produced - aven though the aircraft could have become a basis for a long-range interceptor that would replace by time the PVO's Tupolew Tu-28P (ASCC code "Fiddler"), a large aircraft armed solely with missiles.

Despite limitations, the Tu-28P served well in its role, but the concept of a very fast interceptor aircraft, lingered on, since the Soviet Union had large areas to defend against aerial intruders, esp. from the North and the East. High speed, coupled with long range and the ability to intercept an incoming target at long distances independently from ground guidance had high priority for the Soviet Air Defence Forces. Even though no official requirement was issued, the concept of Izdeliye 301 from the Seventies was eventually developed further into the fixed-wing "Izdeliye 701" ultra-long-range high-altitude interceptor in the 1980ies.

The impulse for this new approach came when Oleg S. Samoylovich joined the Mikoyan OKB after having worked at Suchoi OKB on the T-60S missile carrier project. Similar in overall design to the former 301, the 701 was primarily intended as a kind of successor for the MiG-31 Foxhound for the 21st century, which just had completed flight tests and was about to enter PVO's front line units.

Being based on a long range cruise missile carrier, the 701 would have been a huge plane, featuring a length of 30-31m, a wing span of 19m (featuring a highly swept double delta wing) and having a maximum TOW of 70 tons! Target performance figures included a top speed of 2.500km/h, a cruising speed of 2.100km/h at 17.000m and an effective range of 7.000km in supersonic or 11.000km in subsonic mode. Eventually, the 701 program was mothballed, too, being too ambitious and expensive for a specialized development that could also have been a fighter version of the Tu-22 bomber!

Anyway, while the MiG-31 was successfully introduced in 1979 and had evolved in into a capable long-range interceptor with a top speed of more than Mach 3 (limited to Mach 2.8 in order to protect the aircraft's structural integrity), MiG OKB decided in 1984 to take further action and to develop a next-generation technology demonstrator, knowing that even the formidable "Foxhound" was only an interim solution on the way to a true "Four plus" of even a 6th generation fighter. Other new threats like low-flying cruise missiles, the USAF's "Project Pluto" or the assumed SR-71 Mach 5 successor “Aurora” kept Soviet military officials on the edge of their seats, too.

Main objective was to expand the Foxhound's state-of the-art performance, and coiple it with modern features like aerodynamic instability, supercruise, stealth features and further development potential.

The aircraft's core mission objectives comprised:

- Provide strategic air defense and surveillance in areas not covered by ground-based air defense systems (incl. guidance of other aircraft with less sophisticated avionics)

- Top speed of Mach 3.2 or more in a dash and cruise at Mach 3.0 for prolonged periods

- Long range/high speed interception of airspace intruders of any kind, including low flying cruise missiles, UAVs and helicopters

- Intercept cruise missiles and their launch aircraft from sea level up to 30.000m altitude by reaching missile launch range in the lowest possible time after departing the loiter area

Because funding was scarce and no official GOR had been issued, the project was taken on as a private venture. The new project was internally known as "Izdeliye 710" or "71.0". It was based on both 301 and 701 layout ideas and the wind tunnel experiences with their unusual layouts, as well as Oleg Samoylovich's experience with the Suchoi T-4 Mach 3 bomber project and the T-60S.

"Izdeliye 710" was from the start intended only as a proof-of-concept prototype, yet fully functional. It would also incorporate new technologies like heat-resistant ceramics against kinetic heating at prolonged high speeds (the airframe had to resist temperatures of 300°C/570°F and more for considerable periods), but with potential for future development into a full-fledged interceptor, penetrator and reconnaissance aircraft.

Overall, “Izdeliye 710" looked like a shrinked version of a mix of both former MiG OKB 301 and 701 designs, limited to the MiG-31's weight class of about 40 tons TOW. Compared with the former designs, the airframe received an aerodynamically more refined, partly blended, slender fuselage that also incorporated mild stealth features like a “clean” underside, softened contours and partly shielded air intakes. Structurally, the airframe's speed limit was set at Mach 3.8.

From the earlier 301 design,the plane retained the variable geometry wing. Despite the system's complexity and weight, this solution was deemed to be the best approach for a combination of a high continuous top speed, extended loiter time in the mission’s patrol areas and good performance on improvised airfields. Minimum sweep was a mere 10°, while, fully swept at 68°, the wings blended into the LERXes. Additional lift was created through the fuselage shape itself, so that aerodynamic surfaces and therefore drag could be reduced.

Pilot and radar operator sat in tandem under a common canopy with rather limited sight. The cockpit was equipped with a modern glass cockpit with LCD screens. The aircraft’s two engines were, again, placed in a large, mutual nacelle on the upper rear fuselage, fed by large air intakes with two-dimensional vertical ramps and a carefully modulated airflow over the aircraft’s dorsal area.

Initially, the 71.0 was to be powered by a pair of Soloviev D-30F6 afterburning turbofans with a dry thrust of 93 kN (20,900 lbf) each, and with 152 kN (34,172 lbf) with full afterburner. These were the same engines that powered the MiG-31, but there were high hopes for the Kolesov NK-101 engine: a variable bypass engine with a maximum thrust in the 200kN range, at the time of the 71.0's design undergoing bench tests and originally developed for the advanced Suchoj T-4MS strike aircraft.

With the D-30F6, the 71.0 was expected to reach Mach 3.2 (making the aircraft capable of effectively intercepting the SR-71), but the NK-101 would offer in pure jet mode a top speed in excess of Mach 3.5 and also improve range and especially loiter time when running as a subsonic turbofan engine.

A single fin with an all-moving top and an additional deep rudder at its base was placed on top of the engine nacelle. Additional maneuverability at lower speed was achieved by retractable, all-moving foreplanes, stowed in narrow slits under the cockpit. Longitudinal stability at high speed was improved through deflectable stabilizers: these were kept horizontal for take-off and added to the overall lift, but they could be folded down by up to 60° in flight, acting additionally as stabilizer strakes.

Due to the aircraft’s slender shape and unique proportions, the 71.0 quickly received the unofficial nickname "жура́вль" (‘Zhurávl' = Crane). The aircaft’s stalky impression was emphasized even more through its unusual landing gear arrangement: Due to the limited internal space for the main landing gear wells between the weapons bay, the wing folding mechanisms and the engine nacelle, MiG OKB decided to incorporate a bicycle landing gear, normally a trademark of Yakovlew OKB designs, but a conventional landing gear could simply not be mounted, or its construction would have become much too heavy and complex.

In order to facilitate operations from improvised airfields and on snow the landing gear featured twin front wheels on a conventional strut and a single four wheel bogie as main wheels. Smaller, single stabilizer wheels were mounted on outriggers that retracted into slender fairings at the wings’ fixed section trailing edge, reminiscent of early Tupolev designs.

All standard air-to-air weaponry, as well as fuel, was to be carried internally. Main armament would be the K-100 missile (in service eventually designated R-100), stored in a large weapons bay behind the cockpit on a rotary mount. The K-100 had been under development at that time at NPO Novator, internally coded ‘Izdeliye 172’. The K-100 missile was an impressive weapon, and specifically designed to attack vital and heavily defended aerial targets like NATO’s AWACS aircraft at BVR distance.

Being 15’ (4.57 m) long and weighing 1.370 lb (620 kg), this huge ultra-long-range weapon had a maximum range of 250 mi (400 km) in a cruise/glide profile and attained a speed of Mach 6 with its solid rocket engine. This range could be boosted even further with a pair of jettisonable ramjets in tubular pods on the missile’s flanks for another 60 mi (100 km). The missile could attack targets ranging in altitude between 15 – 25,000 meters.

The weapon would initially be allocated to a specified target through the launch aircraft’s on-board radar and sent via inertial guidance into the target’s direction. Closing in, the K-100’s Agat 9B-1388 active seeker would identify the target, lock on, and independently attack it, also in coordination with other K-100’s shot at the same target, so that the attack would be coordinated in time and approach directions in order to overload defense and ensure a hit.

The 71.0’s internal mount could hold four of these large missiles, or, alternatively, the same number of the MiG-31’s R-33 AAMs. The mount also had a slot for the storage of additional mid- and short-range missiles for self-defense, e .g. three R-60 or two R-73 AAMs. An internal gun was not considered to be necessary, since the 71.0 or potential derivatives would fight their targets at very long distances and rather rely on a "hit-and-run" tactic, sacrificing dogfight capabilities for long loitering time in stand-by mode, high approach speed and outstanding acceleration and altitude performance.

Anyway, provisions were made to carry a Gsh-301-250 gun pod on a retractable hardpoint in the weapons bay instead of a K-100. Alternatively, such pods could be carried externally on four optional wing root pylons, which were primarily intended for PTB-1500 or PTB-3000 drop tanks, or further missiles - theoretically, a maximum of ten K-100 missiles could be carried, plus a pair of short-range AAMs.

Additionally, a "buddy-to-buffy" IFR set with a retractable drogue (probably the same system as used on the Su-24) was tested (71.2 was outfitted with a retractable refuelling probe in front of the cockpit), as well as the carriage of simple iron bombs or nuclear stores, to be delivered from very high altitudes. Several pallets with cameras and sensors (e .g. a high resolution SLAR) were also envisioned, which could easily replace the missile mounts and the folding weapon bay covers for recce missions.

Since there had been little official support for the project, work on the 710 up to the hardware stage made only little progress, since the MiG-31 already filled the long-range interceptor role in a sufficient fashion and offered further development potential.

A wooden mockup of the cockpit section was presented to PVO and VVS officials in 1989, and airframe work (including tests with composite materials on structural parts, including ceramic tiles for leading edges) were undertaken throughout 1990 and 1991, including test rigs for the engine nacelle and the swing wing mechanism.

Eventually, the collapse of the Soviet Union in 1991 suddenly stopped most of the project work, after two prototype airframes had been completed. Their internal designations were Izdeliye 71.1 and 71.2, respectively. It took a while until the political situation as well as the ex-Soviet Air Force’s status were settled, and work on Izdeliye 710 resumed at a slow pace.

After taking two years to be completed, 71.1 eventually made its roll-out and maiden flight in summer 1994, just when MiG-31 production had ended. MiG OKB still had high hopes in this aircraft, since the MiG-31 would have to be replaced in the next couple of years and "Izdeliye 710" was just in time for the potential procurement process. The first prototype wore a striking all-white livery, with dark grey ceramic tiles on the wings’ leading edges standing out prominently – in this guise and with its futuristic lines the slender aircraft reminded a lot of the American Space Shuttle.

71.1 was primarily intended for engine and flight tests (esp. for the eagerly awaited NK-101 engines), as well as for the development of the envisioned ramjet propulsion system for full-scale production and further development of Izdeliye 710 into a Mach 3+ interceptor. No mission avionics were initially fitted to this plane, but it carried a comprehensive test equipment suite and ballast.

Its sister ship 71.2 flew for the first time in late 1994, wearing a more unpretentious grey/bare metal livery. This plane was earmarked for avionics development and weapons integration, especially as a test bed for the K-100 missile, which shared Izdeliye 710’s fate of being a leftover Soviet project with an uncertain future and an even more corny funding outlook.

Anyway, aircraft 71.2 was from the start equipped with a complete RP-31 ('Zaslon-M') weapon control system, which had been under development at that time as an upgrade for the Russian MiG-31 fleet being part of the radar’s development program secured financial support from the government and allowed the flight tests to continue. The RP-31 possessed a maximum detection range of 400 km (250 mi) against airliner-sized targets at high altitude or 200 km against fighter-sized targets; the typical width of detection along the front was given as 225 km. The system could track 24 airborne targets at one time at a range of 120 km, 6 of which could be simultaneously attacked with missiles.

With these capabilities the RP-31 suite could, coupled with an appropriate carrier airframe, fulfil the originally intended airspace control function and would render a dedicated and highly vulnerable airspace control aircraft (like the Beriev A-50 derivative of the Il-76 transport) more or less obsolete. A group of four aircraft equipped with the 'Zaslon-M' suite would be able to permanently control an area of airspace across a total length of 800–900 km, while having ultra-long range weapons at hand to counter any intrusion into airspace with a quicker reaction time than any ground-based fighter on QRA duty. The 71.0, outfitted with the RP-31/K-100 system, would have posed a serious threat to any aggressor.

In March 1995 both prototypes were eventually transferred to the Kerchenskaya Guards Air Base at Savasleyka in the Oblast Vladimir, 300 km east of Mocsow, where they received tactical codes of '11 Blue' and '12 Blue'. Besides the basic test program and the RP-31/K-100 system tests, both machines were directly evaluated against the MiG-31 and Su-27 fighters by the Air Force's 4th TsBPi PLS, based at the same site.

Both aircraft exceeded expectations, but also fell short in certain aspects. The 71.0’s calculated top speed of Mach 3.2 was achieved during the tests with a top speed of 3,394 km/h (2.108 mph) at 21,000 m (69.000 ft). Top speed at sea level was confirmed at 1.200 km/h (745 mph) indicated airspeed.

Combat radius with full weapon load and internal fuel only was limited to 1,450 km (900 mi) at Mach 0.8 and at an altitude of 10,000 m (33,000 ft), though, and it sank to a mere 720 km (450 mi) at Mach 2.35 and at an altitude of 18,000 m (59,000 ft). Combat range with 4x K-100 internally and 2 drop tanks was settled at 3,000 km (1,860 mi), rising to 5,400 km (3,360 mi) with one in-flight refueling, tested with the 71.2. Endurance at altitude was only slightly above 3 hours, though. Service ceiling was 22,800 m (74,680 ft), 2.000 m higher than the MiG-31.

While these figures were impressive, Soviet officials were not truly convinced: they did not show a significant improvement over the simpler MiG-31. MiG OKB tried to persuade the government into more flight tests and begged for access to the NK-101, but the Soviet Union's collapse halted this project, too, so that both Izdeliye 710 had to keep the Soloviev D-30F6.

Little is known about the Izdeliye 710 project’s progress or further developments. The initial tests lasted until at least 1997, and obviously the updated MiG-31M received official favor instead of a completely new aircraft. The K-100 was also dropped, since the R-33 missile and later its R-37 derivative sufficiently performed in the long-range aerial strike role.

Development on the aircraft as such seemed to have stopped with the advent of modernized Su-27 derivatives and the PAK FA project, resulting in the Suchoi T-50 prototype. Unconfirmed reports suggest that one of the prototypes (probably 71.1) was used in the development of the N014 Pulse-Doppler radar with a passive electronically scanned array antenna in the wake of the MFI program. The N014 was designed with a range of 420 km, detection target of 250km to 1m and able to track 40 targets while able to shoot against 20.

Most interestingly, Izdeliye 710 was never officially presented to the public, but NATO became aware of its development through satellite pictures in the early Nineties and the aircraft consequently received the ASCC reporting codename "Fastback".

Only few and rather corny information leaked into the West, and the 301 was believed not only to act as a reconnaissance plane , it was also believed to have (nuclear) bombing capabilities. Despite wind tunnel testing with models, no hardware of the 301 was ever produced - aven though the aircraft could have become a basis for a long-range interceptor that would replace by time the PVO's Tupolew Tu-28P (ASCC code "Fiddler"), a large aircraft armed solely with missiles.

Despite limitations, the Tu-28P served well in its role, but the concept of a very fast interceptor aircraft, lingered on, since the Soviet Union had large areas to defend against aerial intruders, esp. from the North and the East. High speed, coupled with long range and the ability to intercept an incoming target at long distances independently from ground guidance had high priority for the Soviet Air Defence Forces. Even though no official requirement was issued, the concept of Izdeliye 301 from the Seventies was eventually developed further into the fixed-wing "Izdeliye 701" ultra-long-range high-altitude interceptor in the 1980ies.

The impulse for this new approach came when Oleg S. Samoylovich joined the Mikoyan OKB after having worked at Suchoi OKB on the T-60S missile carrier project. Similar in overall design to the former 301, the 701 was primarily intended as a kind of successor for the MiG-31 Foxhound for the 21st century, which just had completed flight tests and was about to enter PVO's front line units.

Being based on a long range cruise missile carrier, the 701 would have been a huge plane, featuring a length of 30-31m, a wing span of 19m (featuring a highly swept double delta wing) and having a maximum TOW of 70 tons! Target performance figures included a top speed of 2.500km/h, a cruising speed of 2.100km/h at 17.000m and an effective range of 7.000km in supersonic or 11.000km in subsonic mode. Eventually, the 701 program was mothballed, too, being too ambitious and expensive for a specialized development that could also have been a fighter version of the Tu-22 bomber!

Anyway, while the MiG-31 was successfully introduced in 1979 and had evolved in into a capable long-range interceptor with a top speed of more than Mach 3 (limited to Mach 2.8 in order to protect the aircraft's structural integrity), MiG OKB decided in 1984 to take further action and to develop a next-generation technology demonstrator, knowing that even the formidable "Foxhound" was only an interim solution on the way to a true "Four plus" of even a 6th generation fighter. Other new threats like low-flying cruise missiles, the USAF's "Project Pluto" or the assumed SR-71 Mach 5 successor “Aurora” kept Soviet military officials on the edge of their seats, too.

Main objective was to expand the Foxhound's state-of the-art performance, and coiple it with modern features like aerodynamic instability, supercruise, stealth features and further development potential.

The aircraft's core mission objectives comprised:

- Provide strategic air defense and surveillance in areas not covered by ground-based air defense systems (incl. guidance of other aircraft with less sophisticated avionics)

- Top speed of Mach 3.2 or more in a dash and cruise at Mach 3.0 for prolonged periods

- Long range/high speed interception of airspace intruders of any kind, including low flying cruise missiles, UAVs and helicopters

- Intercept cruise missiles and their launch aircraft from sea level up to 30.000m altitude by reaching missile launch range in the lowest possible time after departing the loiter area

Because funding was scarce and no official GOR had been issued, the project was taken on as a private venture. The new project was internally known as "Izdeliye 710" or "71.0". It was based on both 301 and 701 layout ideas and the wind tunnel experiences with their unusual layouts, as well as Oleg Samoylovich's experience with the Suchoi T-4 Mach 3 bomber project and the T-60S.

"Izdeliye 710" was from the start intended only as a proof-of-concept prototype, yet fully functional. It would also incorporate new technologies like heat-resistant ceramics against kinetic heating at prolonged high speeds (the airframe had to resist temperatures of 300°C/570°F and more for considerable periods), but with potential for future development into a full-fledged interceptor, penetrator and reconnaissance aircraft.

Overall, “Izdeliye 710" looked like a shrinked version of a mix of both former MiG OKB 301 and 701 designs, limited to the MiG-31's weight class of about 40 tons TOW. Compared with the former designs, the airframe received an aerodynamically more refined, partly blended, slender fuselage that also incorporated mild stealth features like a “clean” underside, softened contours and partly shielded air intakes. Structurally, the airframe's speed limit was set at Mach 3.8.

From the earlier 301 design,the plane retained the variable geometry wing. Despite the system's complexity and weight, this solution was deemed to be the best approach for a combination of a high continuous top speed, extended loiter time in the mission’s patrol areas and good performance on improvised airfields. Minimum sweep was a mere 10°, while, fully swept at 68°, the wings blended into the LERXes. Additional lift was created through the fuselage shape itself, so that aerodynamic surfaces and therefore drag could be reduced.

Pilot and radar operator sat in tandem under a common canopy with rather limited sight. The cockpit was equipped with a modern glass cockpit with LCD screens. The aircraft’s two engines were, again, placed in a large, mutual nacelle on the upper rear fuselage, fed by large air intakes with two-dimensional vertical ramps and a carefully modulated airflow over the aircraft’s dorsal area.

Initially, the 71.0 was to be powered by a pair of Soloviev D-30F6 afterburning turbofans with a dry thrust of 93 kN (20,900 lbf) each, and with 152 kN (34,172 lbf) with full afterburner. These were the same engines that powered the MiG-31, but there were high hopes for the Kolesov NK-101 engine: a variable bypass engine with a maximum thrust in the 200kN range, at the time of the 71.0's design undergoing bench tests and originally developed for the advanced Suchoj T-4MS strike aircraft.

With the D-30F6, the 71.0 was expected to reach Mach 3.2 (making the aircraft capable of effectively intercepting the SR-71), but the NK-101 would offer in pure jet mode a top speed in excess of Mach 3.5 and also improve range and especially loiter time when running as a subsonic turbofan engine.

A single fin with an all-moving top and an additional deep rudder at its base was placed on top of the engine nacelle. Additional maneuverability at lower speed was achieved by retractable, all-moving foreplanes, stowed in narrow slits under the cockpit. Longitudinal stability at high speed was improved through deflectable stabilizers: these were kept horizontal for take-off and added to the overall lift, but they could be folded down by up to 60° in flight, acting additionally as stabilizer strakes.

Due to the aircraft’s slender shape and unique proportions, the 71.0 quickly received the unofficial nickname "жура́вль" (‘Zhurávl' = Crane). The aircaft’s stalky impression was emphasized even more through its unusual landing gear arrangement: Due to the limited internal space for the main landing gear wells between the weapons bay, the wing folding mechanisms and the engine nacelle, MiG OKB decided to incorporate a bicycle landing gear, normally a trademark of Yakovlew OKB designs, but a conventional landing gear could simply not be mounted, or its construction would have become much too heavy and complex.

In order to facilitate operations from improvised airfields and on snow the landing gear featured twin front wheels on a conventional strut and a single four wheel bogie as main wheels. Smaller, single stabilizer wheels were mounted on outriggers that retracted into slender fairings at the wings’ fixed section trailing edge, reminiscent of early Tupolev designs.

All standard air-to-air weaponry, as well as fuel, was to be carried internally. Main armament would be the K-100 missile (in service eventually designated R-100), stored in a large weapons bay behind the cockpit on a rotary mount. The K-100 had been under development at that time at NPO Novator, internally coded ‘Izdeliye 172’. The K-100 missile was an impressive weapon, and specifically designed to attack vital and heavily defended aerial targets like NATO’s AWACS aircraft at BVR distance.

Being 15’ (4.57 m) long and weighing 1.370 lb (620 kg), this huge ultra-long-range weapon had a maximum range of 250 mi (400 km) in a cruise/glide profile and attained a speed of Mach 6 with its solid rocket engine. This range could be boosted even further with a pair of jettisonable ramjets in tubular pods on the missile’s flanks for another 60 mi (100 km). The missile could attack targets ranging in altitude between 15 – 25,000 meters.

The weapon would initially be allocated to a specified target through the launch aircraft’s on-board radar and sent via inertial guidance into the target’s direction. Closing in, the K-100’s Agat 9B-1388 active seeker would identify the target, lock on, and independently attack it, also in coordination with other K-100’s shot at the same target, so that the attack would be coordinated in time and approach directions in order to overload defense and ensure a hit.

The 71.0’s internal mount could hold four of these large missiles, or, alternatively, the same number of the MiG-31’s R-33 AAMs. The mount also had a slot for the storage of additional mid- and short-range missiles for self-defense, e .g. three R-60 or two R-73 AAMs. An internal gun was not considered to be necessary, since the 71.0 or potential derivatives would fight their targets at very long distances and rather rely on a "hit-and-run" tactic, sacrificing dogfight capabilities for long loitering time in stand-by mode, high approach speed and outstanding acceleration and altitude performance.

Anyway, provisions were made to carry a Gsh-301-250 gun pod on a retractable hardpoint in the weapons bay instead of a K-100. Alternatively, such pods could be carried externally on four optional wing root pylons, which were primarily intended for PTB-1500 or PTB-3000 drop tanks, or further missiles - theoretically, a maximum of ten K-100 missiles could be carried, plus a pair of short-range AAMs.

Additionally, a "buddy-to-buffy" IFR set with a retractable drogue (probably the same system as used on the Su-24) was tested (71.2 was outfitted with a retractable refuelling probe in front of the cockpit), as well as the carriage of simple iron bombs or nuclear stores, to be delivered from very high altitudes. Several pallets with cameras and sensors (e .g. a high resolution SLAR) were also envisioned, which could easily replace the missile mounts and the folding weapon bay covers for recce missions.

Since there had been little official support for the project, work on the 710 up to the hardware stage made only little progress, since the MiG-31 already filled the long-range interceptor role in a sufficient fashion and offered further development potential.

A wooden mockup of the cockpit section was presented to PVO and VVS officials in 1989, and airframe work (including tests with composite materials on structural parts, including ceramic tiles for leading edges) were undertaken throughout 1990 and 1991, including test rigs for the engine nacelle and the swing wing mechanism.

Eventually, the collapse of the Soviet Union in 1991 suddenly stopped most of the project work, after two prototype airframes had been completed. Their internal designations were Izdeliye 71.1 and 71.2, respectively. It took a while until the political situation as well as the ex-Soviet Air Force’s status were settled, and work on Izdeliye 710 resumed at a slow pace.

After taking two years to be completed, 71.1 eventually made its roll-out and maiden flight in summer 1994, just when MiG-31 production had ended. MiG OKB still had high hopes in this aircraft, since the MiG-31 would have to be replaced in the next couple of years and "Izdeliye 710" was just in time for the potential procurement process. The first prototype wore a striking all-white livery, with dark grey ceramic tiles on the wings’ leading edges standing out prominently – in this guise and with its futuristic lines the slender aircraft reminded a lot of the American Space Shuttle.

71.1 was primarily intended for engine and flight tests (esp. for the eagerly awaited NK-101 engines), as well as for the development of the envisioned ramjet propulsion system for full-scale production and further development of Izdeliye 710 into a Mach 3+ interceptor. No mission avionics were initially fitted to this plane, but it carried a comprehensive test equipment suite and ballast.

Its sister ship 71.2 flew for the first time in late 1994, wearing a more unpretentious grey/bare metal livery. This plane was earmarked for avionics development and weapons integration, especially as a test bed for the K-100 missile, which shared Izdeliye 710’s fate of being a leftover Soviet project with an uncertain future and an even more corny funding outlook.

Anyway, aircraft 71.2 was from the start equipped with a complete RP-31 ('Zaslon-M') weapon control system, which had been under development at that time as an upgrade for the Russian MiG-31 fleet being part of the radar’s development program secured financial support from the government and allowed the flight tests to continue. The RP-31 possessed a maximum detection range of 400 km (250 mi) against airliner-sized targets at high altitude or 200 km against fighter-sized targets; the typical width of detection along the front was given as 225 km. The system could track 24 airborne targets at one time at a range of 120 km, 6 of which could be simultaneously attacked with missiles.

With these capabilities the RP-31 suite could, coupled with an appropriate carrier airframe, fulfil the originally intended airspace control function and would render a dedicated and highly vulnerable airspace control aircraft (like the Beriev A-50 derivative of the Il-76 transport) more or less obsolete. A group of four aircraft equipped with the 'Zaslon-M' suite would be able to permanently control an area of airspace across a total length of 800–900 km, while having ultra-long range weapons at hand to counter any intrusion into airspace with a quicker reaction time than any ground-based fighter on QRA duty. The 71.0, outfitted with the RP-31/K-100 system, would have posed a serious threat to any aggressor.

In March 1995 both prototypes were eventually transferred to the Kerchenskaya Guards Air Base at Savasleyka in the Oblast Vladimir, 300 km east of Mocsow, where they received tactical codes of '11 Blue' and '12 Blue'. Besides the basic test program and the RP-31/K-100 system tests, both machines were directly evaluated against the MiG-31 and Su-27 fighters by the Air Force's 4th TsBPi PLS, based at the same site.

Both aircraft exceeded expectations, but also fell short in certain aspects. The 71.0’s calculated top speed of Mach 3.2 was achieved during the tests with a top speed of 3,394 km/h (2.108 mph) at 21,000 m (69.000 ft). Top speed at sea level was confirmed at 1.200 km/h (745 mph) indicated airspeed.

Combat radius with full weapon load and internal fuel only was limited to 1,450 km (900 mi) at Mach 0.8 and at an altitude of 10,000 m (33,000 ft), though, and it sank to a mere 720 km (450 mi) at Mach 2.35 and at an altitude of 18,000 m (59,000 ft). Combat range with 4x K-100 internally and 2 drop tanks was settled at 3,000 km (1,860 mi), rising to 5,400 km (3,360 mi) with one in-flight refueling, tested with the 71.2. Endurance at altitude was only slightly above 3 hours, though. Service ceiling was 22,800 m (74,680 ft), 2.000 m higher than the MiG-31.

While these figures were impressive, Soviet officials were not truly convinced: they did not show a significant improvement over the simpler MiG-31. MiG OKB tried to persuade the government into more flight tests and begged for access to the NK-101, but the Soviet Union's collapse halted this project, too, so that both Izdeliye 710 had to keep the Soloviev D-30F6.

Little is known about the Izdeliye 710 project’s progress or further developments. The initial tests lasted until at least 1997, and obviously the updated MiG-31M received official favor instead of a completely new aircraft. The K-100 was also dropped, since the R-33 missile and later its R-37 derivative sufficiently performed in the long-range aerial strike role.

Development on the aircraft as such seemed to have stopped with the advent of modernized Su-27 derivatives and the PAK FA project, resulting in the Suchoi T-50 prototype. Unconfirmed reports suggest that one of the prototypes (probably 71.1) was used in the development of the N014 Pulse-Doppler radar with a passive electronically scanned array antenna in the wake of the MFI program. The N014 was designed with a range of 420 km, detection target of 250km to 1m and able to track 40 targets while able to shoot against 20.

Most interestingly, Izdeliye 710 was never officially presented to the public, but NATO became aware of its development through satellite pictures in the early Nineties and the aircraft consequently received the ASCC reporting codename "Fastback".

Only few and rather corny information leaked into the West, and the 301 was believed not only to act as a reconnaissance plane , it was also believed to have (nuclear) bombing capabilities. Despite wind tunnel testing with models, no hardware of the 301 was ever produced - aven though the aircraft could have become a basis for a long-range interceptor that would replace by time the PVO's Tupolew Tu-28P (ASCC code "Fiddler"), a large aircraft armed solely with missiles.

Despite limitations, the Tu-28P served well in its role, but the concept of a very fast interceptor aircraft, lingered on, since the Soviet Union had large areas to defend against aerial intruders, esp. from the North and the East. High speed, coupled with long range and the ability to intercept an incoming target at long distances independently from ground guidance had high priority for the Soviet Air Defence Forces. Even though no official requirement was issued, the concept of Izdeliye 301 from the Seventies was eventually developed further into the fixed-wing "Izdeliye 701" ultra-long-range high-altitude interceptor in the 1980ies.

The impulse for this new approach came when Oleg S. Samoylovich joined the Mikoyan OKB after having worked at Suchoi OKB on the T-60S missile carrier project. Similar in overall design to the former 301, the 701 was primarily intended as a kind of successor for the MiG-31 Foxhound for the 21st century, which just had completed flight tests and was about to enter PVO's front line units.

Being based on a long range cruise missile carrier, the 701 would have been a huge plane, featuring a length of 30-31m, a wing span of 19m (featuring a highly swept double delta wing) and having a maximum TOW of 70 tons! Target performance figures included a top speed of 2.500km/h, a cruising speed of 2.100km/h at 17.000m and an effective range of 7.000km in supersonic or 11.000km in subsonic mode. Eventually, the 701 program was mothballed, too, being too ambitious and expensive for a specialized development that could also have been a fighter version of the Tu-22 bomber!

Anyway, while the MiG-31 was successfully introduced in 1979 and had evolved in into a capable long-range interceptor with a top speed of more than Mach 3 (limited to Mach 2.8 in order to protect the aircraft's structural integrity), MiG OKB decided in 1984 to take further action and to develop a next-generation technology demonstrator, knowing that even the formidable "Foxhound" was only an interim solution on the way to a true "Four plus" of even a 6th generation fighter. Other new threats like low-flying cruise missiles, the USAF's "Project Pluto" or the assumed SR-71 Mach 5 successor “Aurora” kept Soviet military officials on the edge of their seats, too.

Main objective was to expand the Foxhound's state-of the-art performance, and coiple it with modern features like aerodynamic instability, supercruise, stealth features and further development potential.

The aircraft's core mission objectives comprised:

- Provide strategic air defense and surveillance in areas not covered by ground-based air defense systems (incl. guidance of other aircraft with less sophisticated avionics)

- Top speed of Mach 3.2 or more in a dash and cruise at Mach 3.0 for prolonged periods

- Long range/high speed interception of airspace intruders of any kind, including low flying cruise missiles, UAVs and helicopters

- Intercept cruise missiles and their launch aircraft from sea level up to 30.000m altitude by reaching missile launch range in the lowest possible time after departing the loiter area

Because funding was scarce and no official GOR had been issued, the project was taken on as a private venture. The new project was internally known as "Izdeliye 710" or "71.0". It was based on both 301 and 701 layout ideas and the wind tunnel experiences with their unusual layouts, as well as Oleg Samoylovich's experience with the Suchoi T-4 Mach 3 bomber project and the T-60S.

"Izdeliye 710" was from the start intended only as a proof-of-concept prototype, yet fully functional. It would also incorporate new technologies like heat-resistant ceramics against kinetic heating at prolonged high speeds (the airframe had to resist temperatures of 300°C/570°F and more for considerable periods), but with potential for future development into a full-fledged interceptor, penetrator and reconnaissance aircraft.

Overall, “Izdeliye 710" looked like a shrinked version of a mix of both former MiG OKB 301 and 701 designs, limited to the MiG-31's weight class of about 40 tons TOW. Compared with the former designs, the airframe received an aerodynamically more refined, partly blended, slender fuselage that also incorporated mild stealth features like a “clean” underside, softened contours and partly shielded air intakes. Structurally, the airframe's speed limit was set at Mach 3.8.

From the earlier 301 design,the plane retained the variable geometry wing. Despite the system's complexity and weight, this solution was deemed to be the best approach for a combination of a high continuous top speed, extended loiter time in the mission’s patrol areas and good performance on improvised airfields. Minimum sweep was a mere 10°, while, fully swept at 68°, the wings blended into the LERXes. Additional lift was created through the fuselage shape itself, so that aerodynamic surfaces and therefore drag could be reduced.

Pilot and radar operator sat in tandem under a common canopy with rather limited sight. The cockpit was equipped with a modern glass cockpit with LCD screens. The aircraft’s two engines were, again, placed in a large, mutual nacelle on the upper rear fuselage, fed by large air intakes with two-dimensional vertical ramps and a carefully modulated airflow over the aircraft’s dorsal area.

Initially, the 71.0 was to be powered by a pair of Soloviev D-30F6 afterburning turbofans with a dry thrust of 93 kN (20,900 lbf) each, and with 152 kN (34,172 lbf) with full afterburner. These were the same engines that powered the MiG-31, but there were high hopes for the Kolesov NK-101 engine: a variable bypass engine with a maximum thrust in the 200kN range, at the time of the 71.0's design undergoing bench tests and originally developed for the advanced Suchoj T-4MS strike aircraft.

With the D-30F6, the 71.0 was expected to reach Mach 3.2 (making the aircraft capable of effectively intercepting the SR-71), but the NK-101 would offer in pure jet mode a top speed in excess of Mach 3.5 and also improve range and especially loiter time when running as a subsonic turbofan engine.

A single fin with an all-moving top and an additional deep rudder at its base was placed on top of the engine nacelle. Additional maneuverability at lower speed was achieved by retractable, all-moving foreplanes, stowed in narrow slits under the cockpit. Longitudinal stability at high speed was improved through deflectable stabilizers: these were kept horizontal for take-off and added to the overall lift, but they could be folded down by up to 60° in flight, acting additionally as stabilizer strakes.

Due to the aircraft’s slender shape and unique proportions, the 71.0 quickly received the unofficial nickname "жура́вль" (‘Zhurávl' = Crane). The aircaft’s stalky impression was emphasized even more through its unusual landing gear arrangement: Due to the limited internal space for the main landing gear wells between the weapons bay, the wing folding mechanisms and the engine nacelle, MiG OKB decided to incorporate a bicycle landing gear, normally a trademark of Yakovlew OKB designs, but a conventional landing gear could simply not be mounted, or its construction would have become much too heavy and complex.

In order to facilitate operations from improvised airfields and on snow the landing gear featured twin front wheels on a conventional strut and a single four wheel bogie as main wheels. Smaller, single stabilizer wheels were mounted on outriggers that retracted into slender fairings at the wings’ fixed section trailing edge, reminiscent of early Tupolev designs.

All standard air-to-air weaponry, as well as fuel, was to be carried internally. Main armament would be the K-100 missile (in service eventually designated R-100), stored in a large weapons bay behind the cockpit on a rotary mount. The K-100 had been under development at that time at NPO Novator, internally coded ‘Izdeliye 172’. The K-100 missile was an impressive weapon, and specifically designed to attack vital and heavily defended aerial targets like NATO’s AWACS aircraft at BVR distance.

Being 15’ (4.57 m) long and weighing 1.370 lb (620 kg), this huge ultra-long-range weapon had a maximum range of 250 mi (400 km) in a cruise/glide profile and attained a speed of Mach 6 with its solid rocket engine. This range could be boosted even further with a pair of jettisonable ramjets in tubular pods on the missile’s flanks for another 60 mi (100 km). The missile could attack targets ranging in altitude between 15 – 25,000 meters.

The weapon would initially be allocated to a specified target through the launch aircraft’s on-board radar and sent via inertial guidance into the target’s direction. Closing in, the K-100’s Agat 9B-1388 active seeker would identify the target, lock on, and independently attack it, also in coordination with other K-100’s shot at the same target, so that the attack would be coordinated in time and approach directions in order to overload defense and ensure a hit.

The 71.0’s internal mount could hold four of these large missiles, or, alternatively, the same number of the MiG-31’s R-33 AAMs. The mount also had a slot for the storage of additional mid- and short-range missiles for self-defense, e .g. three R-60 or two R-73 AAMs. An internal gun was not considered to be necessary, since the 71.0 or potential derivatives would fight their targets at very long distances and rather rely on a "hit-and-run" tactic, sacrificing dogfight capabilities for long loitering time in stand-by mode, high approach speed and outstanding acceleration and altitude performance.

Anyway, provisions were made to carry a Gsh-301-250 gun pod on a retractable hardpoint in the weapons bay instead of a K-100. Alternatively, such pods could be carried externally on four optional wing root pylons, which were primarily intended for PTB-1500 or PTB-3000 drop tanks, or further missiles - theoretically, a maximum of ten K-100 missiles could be carried, plus a pair of short-range AAMs.

Additionally, a "buddy-to-buffy" IFR set with a retractable drogue (probably the same system as used on the Su-24) was tested (71.2 was outfitted with a retractable refuelling probe in front of the cockpit), as well as the carriage of simple iron bombs or nuclear stores, to be delivered from very high altitudes. Several pallets with cameras and sensors (e .g. a high resolution SLAR) were also envisioned, which could easily replace the missile mounts and the folding weapon bay covers for recce missions.

Since there had been little official support for the project, work on the 710 up to the hardware stage made only little progress, since the MiG-31 already filled the long-range interceptor role in a sufficient fashion and offered further development potential.

A wooden mockup of the cockpit section was presented to PVO and VVS officials in 1989, and airframe work (including tests with composite materials on structural parts, including ceramic tiles for leading edges) were undertaken throughout 1990 and 1991, including test rigs for the engine nacelle and the swing wing mechanism.

Eventually, the collapse of the Soviet Union in 1991 suddenly stopped most of the project work, after two prototype airframes had been completed. Their internal designations were Izdeliye 71.1 and 71.2, respectively. It took a while until the political situation as well as the ex-Soviet Air Force’s status were settled, and work on Izdeliye 710 resumed at a slow pace.

After taking two years to be completed, 71.1 eventually made its roll-out and maiden flight in summer 1994, just when MiG-31 production had ended. MiG OKB still had high hopes in this aircraft, since the MiG-31 would have to be replaced in the next couple of years and "Izdeliye 710" was just in time for the potential procurement process. The first prototype wore a striking all-white livery, with dark grey ceramic tiles on the wings’ leading edges standing out prominently – in this guise and with its futuristic lines the slender aircraft reminded a lot of the American Space Shuttle.

71.1 was primarily intended for engine and flight tests (esp. for the eagerly awaited NK-101 engines), as well as for the development of the envisioned ramjet propulsion system for full-scale production and further development of Izdeliye 710 into a Mach 3+ interceptor. No mission avionics were initially fitted to this plane, but it carried a comprehensive test equipment suite and ballast.

Its sister ship 71.2 flew for the first time in late 1994, wearing a more unpretentious grey/bare metal livery. This plane was earmarked for avionics development and weapons integration, especially as a test bed for the K-100 missile, which shared Izdeliye 710’s fate of being a leftover Soviet project with an uncertain future and an even more corny funding outlook.

Anyway, aircraft 71.2 was from the start equipped with a complete RP-31 ('Zaslon-M') weapon control system, which had been under development at that time as an upgrade for the Russian MiG-31 fleet being part of the radar’s development program secured financial support from the government and allowed the flight tests to continue. The RP-31 possessed a maximum detection range of 400 km (250 mi) against airliner-sized targets at high altitude or 200 km against fighter-sized targets; the typical width of detection along the front was given as 225 km. The system could track 24 airborne targets at one time at a range of 120 km, 6 of which could be simultaneously attacked with missiles.

With these capabilities the RP-31 suite could, coupled with an appropriate carrier airframe, fulfil the originally intended airspace control function and would render a dedicated and highly vulnerable airspace control aircraft (like the Beriev A-50 derivative of the Il-76 transport) more or less obsolete. A group of four aircraft equipped with the 'Zaslon-M' suite would be able to permanently control an area of airspace across a total length of 800–900 km, while having ultra-long range weapons at hand to counter any intrusion into airspace with a quicker reaction time than any ground-based fighter on QRA duty. The 71.0, outfitted with the RP-31/K-100 system, would have posed a serious threat to any aggressor.

In March 1995 both prototypes were eventually transferred to the Kerchenskaya Guards Air Base at Savasleyka in the Oblast Vladimir, 300 km east of Mocsow, where they received tactical codes of '11 Blue' and '12 Blue'. Besides the basic test program and the RP-31/K-100 system tests, both machines were directly evaluated against the MiG-31 and Su-27 fighters by the Air Force's 4th TsBPi PLS, based at the same site.

Both aircraft exceeded expectations, but also fell short in certain aspects. The 71.0’s calculated top speed of Mach 3.2 was achieved during the tests with a top speed of 3,394 km/h (2.108 mph) at 21,000 m (69.000 ft). Top speed at sea level was confirmed at 1.200 km/h (745 mph) indicated airspeed.

Combat radius with full weapon load and internal fuel only was limited to 1,450 km (900 mi) at Mach 0.8 and at an altitude of 10,000 m (33,000 ft), though, and it sank to a mere 720 km (450 mi) at Mach 2.35 and at an altitude of 18,000 m (59,000 ft). Combat range with 4x K-100 internally and 2 drop tanks was settled at 3,000 km (1,860 mi), rising to 5,400 km (3,360 mi) with one in-flight refueling, tested with the 71.2. Endurance at altitude was only slightly above 3 hours, though. Service ceiling was 22,800 m (74,680 ft), 2.000 m higher than the MiG-31.

While these figures were impressive, Soviet officials were not truly convinced: they did not show a significant improvement over the simpler MiG-31. MiG OKB tried to persuade the government into more flight tests and begged for access to the NK-101, but the Soviet Union's collapse halted this project, too, so that both Izdeliye 710 had to keep the Soloviev D-30F6.

Little is known about the Izdeliye 710 project’s progress or further developments. The initial tests lasted until at least 1997, and obviously the updated MiG-31M received official favor instead of a completely new aircraft. The K-100 was also dropped, since the R-33 missile and later its R-37 derivative sufficiently performed in the long-range aerial strike role.

Development on the aircraft as such seemed to have stopped with the advent of modernized Su-27 derivatives and the PAK FA project, resulting in the Suchoi T-50 prototype. Unconfirmed reports suggest that one of the prototypes (probably 71.1) was used in the development of the N014 Pulse-Doppler radar with a passive electronically scanned array antenna in the wake of the MFI program. The N014 was designed with a range of 420 km, detection target of 250km to 1m and able to track 40 targets while able to shoot against 20.

Most interestingly, Izdeliye 710 was never officially presented to the public, but NATO became aware of its development through satellite pictures in the early Nineties and the aircraft consequently received the ASCC reporting codename "Fastback".

Only few and rather corny information leaked into the West, and the 301 was believed not only to act as a reconnaissance plane , it was also believed to have (nuclear) bombing capabilities. Despite wind tunnel testing with models, no hardware of the 301 was ever produced - aven though the aircraft could have become a basis for a long-range interceptor that would replace by time the PVO's Tupolew Tu-28P (ASCC code "Fiddler"), a large aircraft armed solely with missiles.

Despite limitations, the Tu-28P served well in its role, but the concept of a very fast interceptor aircraft, lingered on, since the Soviet Union had large areas to defend against aerial intruders, esp. from the North and the East. High speed, coupled with long range and the ability to intercept an incoming target at long distances independently from ground guidance had high priority for the Soviet Air Defence Forces. Even though no official requirement was issued, the concept of Izdeliye 301 from the Seventies was eventually developed further into the fixed-wing "Izdeliye 701" ultra-long-range high-altitude interceptor in the 1980ies.

The impulse for this new approach came when Oleg S. Samoylovich joined the Mikoyan OKB after having worked at Suchoi OKB on the T-60S missile carrier project. Similar in overall design to the former 301, the 701 was primarily intended as a kind of successor for the MiG-31 Foxhound for the 21st century, which just had completed flight tests and was about to enter PVO's front line units.

Being based on a long range cruise missile carrier, the 701 would have been a huge plane, featuring a length of 30-31m, a wing span of 19m (featuring a highly swept double delta wing) and having a maximum TOW of 70 tons! Target performance figures included a top speed of 2.500km/h, a cruising speed of 2.100km/h at 17.000m and an effective range of 7.000km in supersonic or 11.000km in subsonic mode. Eventually, the 701 program was mothballed, too, being too ambitious and expensive for a specialized development that could also have been a fighter version of the Tu-22 bomber!

Anyway, while the MiG-31 was successfully introduced in 1979 and had evolved in into a capable long-range interceptor with a top speed of more than Mach 3 (limited to Mach 2.8 in order to protect the aircraft's structural integrity), MiG OKB decided in 1984 to take further action and to develop a next-generation technology demonstrator, knowing that even the formidable "Foxhound" was only an interim solution on the way to a true "Four plus" of even a 6th generation fighter. Other new threats like low-flying cruise missiles, the USAF's "Project Pluto" or the assumed SR-71 Mach 5 successor “Aurora” kept Soviet military officials on the edge of their seats, too.

Main objective was to expand the Foxhound's state-of the-art performance, and coiple it with modern features like aerodynamic instability, supercruise, stealth features and further development potential.

The aircraft's core mission objectives comprised:

- Provide strategic air defense and surveillance in areas not covered by ground-based air defense systems (incl. guidance of other aircraft with less sophisticated avionics)

- Top speed of Mach 3.2 or more in a dash and cruise at Mach 3.0 for prolonged periods

- Long range/high speed interception of airspace intruders of any kind, including low flying cruise missiles, UAVs and helicopters

- Intercept cruise missiles and their launch aircraft from sea level up to 30.000m altitude by reaching missile launch range in the lowest possible time after departing the loiter area

Because funding was scarce and no official GOR had been issued, the project was taken on as a private venture. The new project was internally known as "Izdeliye 710" or "71.0". It was based on both 301 and 701 layout ideas and the wind tunnel experiences with their unusual layouts, as well as Oleg Samoylovich's experience with the Suchoi T-4 Mach 3 bomber project and the T-60S.

"Izdeliye 710" was from the start intended only as a proof-of-concept prototype, yet fully functional. It would also incorporate new technologies like heat-resistant ceramics against kinetic heating at prolonged high speeds (the airframe had to resist temperatures of 300°C/570°F and more for considerable periods), but with potential for future development into a full-fledged interceptor, penetrator and reconnaissance aircraft.

Overall, “Izdeliye 710" looked like a shrinked version of a mix of both former MiG OKB 301 and 701 designs, limited to the MiG-31's weight class of about 40 tons TOW. Compared with the former designs, the airframe received an aerodynamically more refined, partly blended, slender fuselage that also incorporated mild stealth features like a “clean” underside, softened contours and partly shielded air intakes. Structurally, the airframe's speed limit was set at Mach 3.8.

From the earlier 301 design,the plane retained the variable geometry wing. Despite the system's complexity and weight, this solution was deemed to be the best approach for a combination of a high continuous top speed, extended loiter time in the mission’s patrol areas and good performance on improvised airfields. Minimum sweep was a mere 10°, while, fully swept at 68°, the wings blended into the LERXes. Additional lift was created through the fuselage shape itself, so that aerodynamic surfaces and therefore drag could be reduced.

Pilot and radar operator sat in tandem under a common canopy with rather limited sight. The cockpit was equipped with a modern glass cockpit with LCD screens. The aircraft’s two engines were, again, placed in a large, mutual nacelle on the upper rear fuselage, fed by large air intakes with two-dimensional vertical ramps and a carefully modulated airflow over the aircraft’s dorsal area.

Initially, the 71.0 was to be powered by a pair of Soloviev D-30F6 afterburning turbofans with a dry thrust of 93 kN (20,900 lbf) each, and with 152 kN (34,172 lbf) with full afterburner. These were the same engines that powered the MiG-31, but there were high hopes for the Kolesov NK-101 engine: a variable bypass engine with a maximum thrust in the 200kN range, at the time of the 71.0's design undergoing bench tests and originally developed for the advanced Suchoj T-4MS strike aircraft.

With the D-30F6, the 71.0 was expected to reach Mach 3.2 (making the aircraft capable of effectively intercepting the SR-71), but the NK-101 would offer in pure jet mode a top speed in excess of Mach 3.5 and also improve range and especially loiter time when running as a subsonic turbofan engine.

A single fin with an all-moving top and an additional deep rudder at its base was placed on top of the engine nacelle. Additional maneuverability at lower speed was achieved by retractable, all-moving foreplanes, stowed in narrow slits under the cockpit. Longitudinal stability at high speed was improved through deflectable stabilizers: these were kept horizontal for take-off and added to the overall lift, but they could be folded down by up to 60° in flight, acting additionally as stabilizer strakes.

Due to the aircraft’s slender shape and unique proportions, the 71.0 quickly received the unofficial nickname "жура́вль" (‘Zhurávl' = Crane). The aircaft’s stalky impression was emphasized even more through its unusual landing gear arrangement: Due to the limited internal space for the main landing gear wells between the weapons bay, the wing folding mechanisms and the engine nacelle, MiG OKB decided to incorporate a bicycle landing gear, normally a trademark of Yakovlew OKB designs, but a conventional landing gear could simply not be mounted, or its construction would have become much too heavy and complex.

In order to facilitate operations from improvised airfields and on snow the landing gear featured twin front wheels on a conventional strut and a single four wheel bogie as main wheels. Smaller, single stabilizer wheels were mounted on outriggers that retracted into slender fairings at the wings’ fixed section trailing edge, reminiscent of early Tupolev designs.

All standard air-to-air weaponry, as well as fuel, was to be carried internally. Main armament would be the K-100 missile (in service eventually designated R-100), stored in a large weapons bay behind the cockpit on a rotary mount. The K-100 had been under development at that time at NPO Novator, internally coded ‘Izdeliye 172’. The K-100 missile was an impressive weapon, and specifically designed to attack vital and heavily defended aerial targets like NATO’s AWACS aircraft at BVR distance.

Being 15’ (4.57 m) long and weighing 1.370 lb (620 kg), this huge ultra-long-range weapon had a maximum range of 250 mi (400 km) in a cruise/glide profile and attained a speed of Mach 6 with its solid rocket engine. This range could be boosted even further with a pair of jettisonable ramjets in tubular pods on the missile’s flanks for another 60 mi (100 km). The missile could attack targets ranging in altitude between 15 – 25,000 meters.

The weapon would initially be allocated to a specified target through the launch aircraft’s on-board radar and sent via inertial guidance into the target’s direction. Closing in, the K-100’s Agat 9B-1388 active seeker would identify the target, lock on, and independently attack it, also in coordination with other K-100’s shot at the same target, so that the attack would be coordinated in time and approach directions in order to overload defense and ensure a hit.

The 71.0’s internal mount could hold four of these large missiles, or, alternatively, the same number of the MiG-31’s R-33 AAMs. The mount also had a slot for the storage of additional mid- and short-range missiles for self-defense, e .g. three R-60 or two R-73 AAMs. An internal gun was not considered to be necessary, since the 71.0 or potential derivatives would fight their targets at very long distances and rather rely on a "hit-and-run" tactic, sacrificing dogfight capabilities for long loitering time in stand-by mode, high approach speed and outstanding acceleration and altitude performance.

Anyway, provisions were made to carry a Gsh-301-250 gun pod on a retractable hardpoint in the weapons bay instead of a K-100. Alternatively, such pods could be carried externally on four optional wing root pylons, which were primarily intended for PTB-1500 or PTB-3000 drop tanks, or further missiles - theoretically, a maximum of ten K-100 missiles could be carried, plus a pair of short-range AAMs.

Additionally, a "buddy-to-buffy" IFR set with a retractable drogue (probably the same system as used on the Su-24) was tested (71.2 was outfitted with a retractable refuelling probe in front of the cockpit), as well as the carriage of simple iron bombs or nuclear stores, to be delivered from very high altitudes. Several pallets with cameras and sensors (e .g. a high resolution SLAR) were also envisioned, which could easily replace the missile mounts and the folding weapon bay covers for recce missions.

Since there had been little official support for the project, work on the 710 up to the hardware stage made only little progress, since the MiG-31 already filled the long-range interceptor role in a sufficient fashion and offered further development potential.

A wooden mockup of the cockpit section was presented to PVO and VVS officials in 1989, and airframe work (including tests with composite materials on structural parts, including ceramic tiles for leading edges) were undertaken throughout 1990 and 1991, including test rigs for the engine nacelle and the swing wing mechanism.

Eventually, the collapse of the Soviet Union in 1991 suddenly stopped most of the project work, after two prototype airframes had been completed. Their internal designations were Izdeliye 71.1 and 71.2, respectively. It took a while until the political situation as well as the ex-Soviet Air Force’s status were settled, and work on Izdeliye 710 resumed at a slow pace.

After taking two years to be completed, 71.1 eventually made its roll-out and maiden flight in summer 1994, just when MiG-31 production had ended. MiG OKB still had high hopes in this aircraft, since the MiG-31 would have to be replaced in the next couple of years and "Izdeliye 710" was just in time for the potential procurement process. The first prototype wore a striking all-white livery, with dark grey ceramic tiles on the wings’ leading edges standing out prominently – in this guise and with its futuristic lines the slender aircraft reminded a lot of the American Space Shuttle.

71.1 was primarily intended for engine and flight tests (esp. for the eagerly awaited NK-101 engines), as well as for the development of the envisioned ramjet propulsion system for full-scale production and further development of Izdeliye 710 into a Mach 3+ interceptor. No mission avionics were initially fitted to this plane, but it carried a comprehensive test equipment suite and ballast.

Its sister ship 71.2 flew for the first time in late 1994, wearing a more unpretentious grey/bare metal livery. This plane was earmarked for avionics development and weapons integration, especially as a test bed for the K-100 missile, which shared Izdeliye 710’s fate of being a leftover Soviet project with an uncertain future and an even more corny funding outlook.

Anyway, aircraft 71.2 was from the start equipped with a complete RP-31 ('Zaslon-M') weapon control system, which had been under development at that time as an upgrade for the Russian MiG-31 fleet being part of the radar’s development program secured financial support from the government and allowed the flight tests to continue. The RP-31 possessed a maximum detection range of 400 km (250 mi) against airliner-sized targets at high altitude or 200 km against fighter-sized targets; the typical width of detection along the front was given as 225 km. The system could track 24 airborne targets at one time at a range of 120 km, 6 of which could be simultaneously attacked with missiles.

With these capabilities the RP-31 suite could, coupled with an appropriate carrier airframe, fulfil the originally intended airspace control function and would render a dedicated and highly vulnerable airspace control aircraft (like the Beriev A-50 derivative of the Il-76 transport) more or less obsolete. A group of four aircraft equipped with the 'Zaslon-M' suite would be able to permanently control an area of airspace across a total length of 800–900 km, while having ultra-long range weapons at hand to counter any intrusion into airspace with a quicker reaction time than any ground-based fighter on QRA duty. The 71.0, outfitted with the RP-31/K-100 system, would have posed a serious threat to any aggressor.

In March 1995 both prototypes were eventually transferred to the Kerchenskaya Guards Air Base at Savasleyka in the Oblast Vladimir, 300 km east of Mocsow, where they received tactical codes of '11 Blue' and '12 Blue'. Besides the basic test program and the RP-31/K-100 system tests, both machines were directly evaluated against the MiG-31 and Su-27 fighters by the Air Force's 4th TsBPi PLS, based at the same site.

Both aircraft exceeded expectations, but also fell short in certain aspects. The 71.0’s calculated top speed of Mach 3.2 was achieved during the tests with a top speed of 3,394 km/h (2.108 mph) at 21,000 m (69.000 ft). Top speed at sea level was confirmed at 1.200 km/h (745 mph) indicated airspeed.

Combat radius with full weapon load and internal fuel only was limited to 1,450 km (900 mi) at Mach 0.8 and at an altitude of 10,000 m (33,000 ft), though, and it sank to a mere 720 km (450 mi) at Mach 2.35 and at an altitude of 18,000 m (59,000 ft). Combat range with 4x K-100 internally and 2 drop tanks was settled at 3,000 km (1,860 mi), rising to 5,400 km (3,360 mi) with one in-flight refueling, tested with the 71.2. Endurance at altitude was only slightly above 3 hours, though. Service ceiling was 22,800 m (74,680 ft), 2.000 m higher than the MiG-31.

While these figures were impressive, Soviet officials were not truly convinced: they did not show a significant improvement over the simpler MiG-31. MiG OKB tried to persuade the government into more flight tests and begged for access to the NK-101, but the Soviet Union's collapse halted this project, too, so that both Izdeliye 710 had to keep the Soloviev D-30F6.

Little is known about the Izdeliye 710 project’s progress or further developments. The initial tests lasted until at least 1997, and obviously the updated MiG-31M received official favor instead of a completely new aircraft. The K-100 was also dropped, since the R-33 missile and later its R-37 derivative sufficiently performed in the long-range aerial strike role.

Development on the aircraft as such seemed to have stopped with the advent of modernized Su-27 derivatives and the PAK FA project, resulting in the Suchoi T-50 prototype. Unconfirmed reports suggest that one of the prototypes (probably 71.1) was used in the development of the N014 Pulse-Doppler radar with a passive electronically scanned array antenna in the wake of the MFI program. The N014 was designed with a range of 420 km, detection target of 250km to 1m and able to track 40 targets while able to shoot against 20.

Most interestingly, Izdeliye 710 was never officially presented to the public, but NATO became aware of its development through satellite pictures in the early Nineties and the aircraft consequently received the ASCC reporting codename "Fastback".