In 1976, Soviet pilot Viktor Belenko escaped with his MiG-25P to Japan, thus revealing RP-SA Smerch-A (NATO: Fox Fire) radar technology to the West. While the USSR was undeniably proud of the MiG-25P's peerless speed and altitude capabilities, it was in reality a rather simple aircraft mechanically. The compromise of the radar was much more serious. The Smerch-A was a much-modernized example of a line of heavy fighter radars dating back to 1956 that in later versions provided Soviet aviation with its first look-down/shoot-down capability.
As an emergency measure, Soviet planners decided to equip all MiG-25Ps with a totally new radar. It was to be based on the most advanced technology then available in the Soviet Union, which was the RP-23 series developed for the MiG-23. The new radar was designed by NII Radyostroyenya (NIIR) (Zhukovsky, Russia), which would eventually become part of NPO Phazotron (before separating again as Phasotron-NIIR). It was called the RP-25MN Sapfir-25 (N005; NATO: High Lark-4) and was basically an enlarged and more powerful version of the RP-23. It had increased ranges of 90 km (detection) and 60 km (tracking). In the look-down/shoot-down mode, the ranges were reduced by 30 percent. The ranges refer to engagements from the target's front hemisphere; in engagements from the rear hemisphere, range was reduced by a further 40 percent. Most importantly, the new radar had additional ECCM capabilities and was integrated with the modernized R-40RD/R-40TD (AA-6 Acrid) air-to-air missiles.
An interesting aspect of Soviet radar sets was that they were developed as a part of so-called "intercept systems." Such an intercept system consisted of a fighter platform, radar and fire-control subsystems, and a missile subsystem. For many years, every Soviet National Air Defense (PVO) and most Frontal Aviation fighters had unique radar and missile systems, used only on particular aircraft. It was a completely different philosophy from the US, where the AIM-4 Falcon, AIM-7 Sparrow and AIM-9 Sidewinder were used throughout the Air Force and Naval Aviation.
The Rise of Phazotron
Phazotron-NIIR was the first bureau in the Soviet Union working on phased-array antennas for fire-control radar sets, although it would be up to NIIP to bring the project off. Earlier, in 1968, NIIR had been tasked with developing the radar for the future MiG-31 (NATO: Foxhound). Engineers prepared two prototype units, dubbed Groza and Vikhr, both based on Saphir-series technology. The final version was called Smerch-100, but the radar failed to meet requirements. As a result, in 1971, NIIR was ordered to pass all the documentation to its consortium partner NIIP. The result was the RP-31 Zaslon (N007; NATO: Flash Dance) radar. The task was very difficult, since one of the main requirements was engaging cruise missiles, and the experienced NIIR had failed to solve the problem of detecting small objects against ground clutter and tracking multiple targets simultaneously. Finally all the problems were solved. First tests of the radar were conducted in 1973, and the system finally reached service in December 1981.
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The new radar made extensive use of solid-state digital technology. It had a large phased-array antenna and high power output. Its front-hemisphere range was 180 km in ideal conditions with no clutter, while the range was 90 km when engaging from the target's rear hemisphere. It could track ten targets simultaneously from a range of 120 to 180 km. In the look-down/shoot-down mode, the range was reduced by 30 percent. The radar was integrated with the R-33 (AA-9 Amos) semi-active radar-guided missile. The MiG-31 could carry four such missiles, and these could be launched simultaneously at four separate targets. The radar could detect and track targets as small as 0.3 sq. m radar cross-section (RCS) to a maximum range of 65 km. The radar's capability caused the Soviets to nickname the MiG-31 "Mini-AWACS."
In the '80s and '90s, there was work conducted on the development of the Zaslon, known as the Zaslon-M. The program was finally cancelled, but it is worth noting because one of its requirements was to engage launched Pershing-2 missiles in flight with long-range R-37 (Adder) active radar-guided missiles.
At the same time, the Soviet Union undertook a similar program called Soyuz, aimed at the development of advanced radar sets for future MiG-29 (NATO: Fulcrum) and Su-27 (NATO: Flanker) fighters. The program started in 1974. Both radar sets were to have maximum commonality; the only difference was to be their size and power. They were to use flat, slotted-array antennas, digital signal processing and pulse-Doppler technology. The aim was to track several targets simultaneously, providing both systems with a track-while-scan mode. The maximum ranges were to be 100 and 200 km, respectively. The MiG-29 radar was to be developed by NIIR, while NIIP would tackle the Su-27 system.
However, despite the success of RP-31, both institutes failed to develop the required systems on time, and less ambitious stopgap solutions were launched in the late '70s. NIIR designed and built the N019 Rubin (NATO: Slot Back) radar for the MiG-29, while NIIP developed the N001 Mech radar for the Su-27 (also called Slot Back by NATO). Both had traditional planar, mechanically scanned antennas. They were based on advanced solid-state technology and digital signal processing, but some radar controls were still partially analog. The main performance concession was that the radars could only track a single target with no track-while-scan capability. The biggest achievement was good look-down/shoot-down performance, with only a 20 percent range reduction. In the case of the N019 Rubin, the ranges were 85 km (detection) and 55 to 60 km (track). The maximum observation angle was 60 degrees up, 38 degrees down and 67 degrees on either side. The range of NIIP's N001 Mech radar fell far short of expectations, with only 140 km against a bomber-type target and 100 km against a fighter-size target. In chase, the ranges were reduced by half. The radar failed to pass state trials in 1982, and in 1985 NIIP was directed to improve it. It finally scraped by state trials in 1991 and was accepted to service, primarily because the alternative was that the Su-27 fighter would be left without any radar at all.
Some misunderstandings arise concerning the number of targets tracked by both types of radar. Some sources provide the number of ten targets tracked simultaneously. The number actually refers to the number of targets about which detection information is provided, which is not track-quality data as understood in the West. The Russian word "soprovozhdyeniye," with a rough English translation of "track," is misleading in this context. In this mode, the radar starts providing information about up to ten selected targets, but before engaging any of them, the pilot has to switch on the "perekhvat" mode, which in Russian means "intercept." In this mode, all the targets except one disappear, and the system prepares fire-control data for missile launch (no track-while-scan mode). Among the other radars (N019 and N001), there is a mode that provides automatic threat assessment and target prioritization. They are both also capable of close-combat work, with a quick vertical-scan mode. Both also work with the same R-27R (AA-10 Alamo) missile, while the Su-27's N001 radar's range enables use of the R-27R1 extended-range version. Both radar sets work in the X-band (about 3 cm wavelength).
In 1986, the N019M Topaz version of the N019 Rubin was developed. The main difference was the introduction of a more powerful digital processor that slightly improved the range (to 90 km) and provided more advanced ECCM capabilities. It was used on MiG-29 9.13 Fulcrum C aircraft. NIIR also developed the N019MP radar, which is an improved version of the N019M Topaz, with a more powerful "Bagiet" processor, for the MiG-29SM/SMT. The maximum range remains about the same, but the radar can detect 20 targets simultaneously, track four and engage two. The radar also has basic air-to-ground functions, such as terrain mapping; ground-target detection, tracking, and ranging; and Doppler beam sharpening. A N019M1 version was proposed for the MiG-29SD and MiG-29SE, which are only prototypes of RSK MiG modernization proposals. It is a pure air-to-air radar but is able to engage four targets simultaneously.
The N019, N019M and N001 radar sets represent the latest examples of second-generation systems introduced into Soviet service. Interestingly, no new types have since been introduced for the Russian Air Force. Therefore, these radar types are widely represented in the Russian, Ukrainian and Belarussian air forces. New radar types were developed but never introduced, although they were exported. Russian military forces simply do not have the money for new technologies.
Export Rays of Hope
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In the late '80s, after overcoming major difficulties, the third generation of fighter radar systems finally started to move forward under a re-launched Soyuz program. Still using common technology (common for NIIP and NIIR under the NPO Phazotron consortium), new fully digital radar systems with electronically scanned antennas were developed for the MiG-29M and Su-27M. None of these fighters reached Russian service, but the radar sets were used on export versions of the fighters.
First, NIIR developed the N010 Zhuk radar for the MiG-29M. The radar was first tested in 1986 on a MiG-29 9.16 prototype. In 1991, it was fitted to MiG-29M (9.15) prototypes. The Zhuk was to be the first Soviet multi-function radar with several air-to-air and air-to-ground modes, but in its basic version, it was still purely air-to-air. The radar had an electronically scanned antenna with a 680 mm diameter. The radar could cooperate with the new R-77 (AA-12 Archer) missiles with active radar seekers. Two missiles could be launched against two separate targets at the same time, and two others shortly afterwards. The radar range is 80 km for front-hemisphere engagements and 40 km for rear-hemisphere engagements. The radar works in the X-band. Depending on range, the radar has +20°, +60° or even +90° of detection/track angle in azimuth and two or four bars in elevation (+60°/–40° maximum). The radar has 5 kW peak power and 1 kW average power. However, the MiG-29M program was cancelled, and the N010 radar never entered service in Russia. It was sold abroad. The Chinese Air Force modernized most of its J-8-II fighters to a J-8-IIM version with a N010 derivative called Zhuk-8-II. It has slightly downgraded capabilities: maximum range is 90 km against a bomber and 70 km against a fighter; it can detect ten targets, track two of them and fire a missile at a single target. The maximum field of view was reduced to +85° in azimuth and in elevation to +55°/–40°.
At the same time, NIIP developed the N011 Bars radar for the Su-27M (Su-35) fighter. The radar had similar capabilities, but the N010 was more powerful and had a larger antenna diameter of 960 mm. The radar had a range of 140 km from the front hemisphere and 65 km on chase. Peak power output was 8 kW, while the average was 2 kW.
A further derivative of the N011 phased-array radar is being fitted to India's Su-30MKI two-seat fighters. The N011M is a multi-mode, dual-frequency (X- and L-band channels) radar that can track 15 air targets and engage four to six targets simultaneously (including motionless targets, such as helicopters). The search range for a target with a 2 sq. m RCS is 80 to 100 km in a head-on position, or 30 to 40 km in a tail-on position. A fighter-size target can be detected at a maximum range of 140 km. The maximum search range for large air targets, such as AWACS, is 400 km. In an air-to-ground mode, it can acquire surface targets at ranges of up to 200 km and provide ground-mapping, terrain-following and terrain-avoidance functions. Small ground targets, like tanks, could be detected out to 40 to 50 km. The radar can also detect naval targets; destroyer-size ships are detected at a range of 120 to 150 km. An interesting feature of the radar is its capability of recognizing air and ground targets based on their unique characteristics in cooperation with IFF. According to the manufacturer, the radar can identify targets using a non-cooperative IFF method.
In the '90s, NIIR prepared a developed version of the Zhuk radar called the N010M Zhuk-M. The pure air-to-air C.90 processor was replaced by a Bagiet, enabling several air-to-ground modes. Among them are ground mapping, detection and track of stationary ground targets, ground-moving-target indicator (MTI), Doppler beam sharpening and terrain avoidance. In the meantime, work on a bigger version of the Zhuk started. The "big" Zhuk-27 was intended for the Su-27 fighter, but the first "big" Zhuk version produced was the Zhuk-M-S — S for Sukhoi. Its peak power increased to 6 kW and average power to 1.5 kW. The antenna diameter was enlarged to 960 mm, like the N011 radar. The maximum range of the N010M was increased to 140 km (50 km in chase). The radar can detect up to 20 targets simultaneously and can track and engage up to four targets with R-77 missiles. It introduced synthetic-aperture-radar (SAR) (3 m resolution) and terrain-following modes in the air-to-ground role. Interestingly, the Zhuk-M-S entered series production for China and is used on Chinese Su-30MKK (except for the first 20, which were equipped with a slightly modernized N001VE).
All the aforementioned Zhuk radars have slotted-array, flat antennas. In the late '80s, a phased-array version was called Zhuk-F (or Zhuk PH when proposed on export, "PH" being equivalent of the Russian "F"). The Zhuk-F was the "small" version and was based on a single-role, basic N010 Zhuk. It was projected for the never-built MiG-29M3 version of the Fulcrum fighter, and the radar also remained in the development stage.
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Using the Zhuk-M-S as a base, NIIR also developed the N010MF Zhuk-MF version (also called Sokol) with a fully phased-array 980 mm antenna (combining the Zhuk-M-S with the Zhuk-F phased-array antenna, but this time "big"). The radar's peak power output was increased to 8 kW and average power to 3 kW. Maximum detection and scan angles in both azimuth and elevation are +70°. The radar can track 30 air targets simultaneously and engage six of them with R-77 missiles. After cancellation of the ambitious N014 program destined for future Russian PAK FA (future fighter system for frontal aviation), it will probably equip the new Sukhoi fighter, winner of the recent PAK FA program (see "Contactor Chosen for New Russian Fighter," JED, July 2002, p. 16).
The final version of the large Zhuk family is the "small" version of "big" Zhuk-MF (Sokol), called the RP-35 Zhemchug. It was developed for the MiG-35, which is a modernized MiG-29M, but survived the aircraft's cancellation. The radar had been proposed for the Chinese J-10 fighter prototype and will probably be its radar when the J-10 reaches series production.
A competing radar for the MiG-29 is the newest NIIP Osa radar system, also provided with a fully scanned array. It has all the same functions as the NIIR Zhuk-MF but is lighter (120 kg) and smaller than even "small" Zhuk versions and can fit in the smaller nose of the MiG-29UB. It has ranges of 85 km (detection) and 65 km (tracking). The radar can detect eight targets, track four and engage two at the same time. Peak power output is 3.5 kW, while average power output is 700 W. The radar works in the X-band. The Osa radar fits on MiG-29UBT prototypes and is also proposed as part of a modernization package for the MiG-29UB, for Russia and foreign customers.
In the late '80s and through the '90s, NIIR also developed a family of lighter radar systems, destined for MiG-21 modernization. The base was a smaller derivative of the Zhuk radar called Kopyo, with a maximum range of 55 to 60 km. The origins of the program date back to 1974, when it was not yet clear whether the future MiG-29 was going to be something like a "smaller" version of the heavy Su-27 fighter or an F-16 equivalent, with good air-to-ground capability but no beyond-visual-range (BVR) air-to-air capability. For a while, it seemed like the latter, and development started on a simple, multi-function radar called Komar that was based on some technologies from the Soyuz program. However, the MiG-29 drifted back toward being a lighter air-superiority fighter, and the Komar was abandoned. The light radar program was relaunched in 1983 as a much smaller and simpler version of the Zhuk to equip modernized MiG-21s. It weighs only 100 kgs but can detect eight targets, track four and engage two of them with R-77 missiles.
A pod-mounted version called N027 Kopyo-25 was developed for Su-39 attack aircraft, but the Su-39 program was cancelled. The Kopyo-F (also called Faraon) is now proposed as a rear-facing radar for tail protection, as a competitor to the NIIP N012 radar developed for the Su-35 fighter and Su-32 fighter-bomber.
The smallest and simplest radar developed by NIIR is the Moskit radar. Originally, the Moskit was to be bigger and was intended for MiG-23 modernization, but it was developed as a "miniaturized" version. It only has a 25 km range and can track one target at a time. It has a +30¡ detection/track angle in azimuth and two or four bars in elevation. It also works in the X-band. The Moskit radar is intended for Indian Jaguar aircraft modernization (in place of the French Agava radar as well as Indian MiG-27 modernization) and will be mounted in a pod. The radar is optimized for naval-target detection and tracking. It only weighs 70 kg.
Finally, it is worth mentioning the Pero phased-array radar antenna system intended for the modernization of Russian Su-30 fighters. Pero can be integrated with the existing N001 radar to increase its performance. The radar range increases to 190 km and the radar would be capable of tracking twelve targets and engaging four of them with R-77 missiles. In late 2001, the Russian Air Force announced that it would modernize five Su-30PU fighters, but the program's future is unknown.
