Showing posts with label Sukhoi. Show all posts
Showing posts with label Sukhoi. Show all posts

19 April 2011

Sukhoi's First Jet Bomber

The Sukhoi Su-10 in its final configuration
Following the end of the Second World War, both the Soviet Union and the West aggressively pursued jet bomber designs after the Luftwaffe had successfully introduced the Arado Ar 234 to combat in the waning months of the war. In the West, many early designs were based on layouts of high-mounted wings with wing-mounted nacelles to allow for a reasonably-sized bomb bay. Similar approaches were taken in the Soviet Union with the design bureaus (called OKBs) of Illyushin, Tupolev, and Sukhoi tapped to develop jet bomber designs to succeed the Soviet Air Force's standard bomber, the piston-powered Tupolev Tu-2. Last summer I had posted about an early Tupolev design that actually did fly, the Tu-12, that was based on the Tu-2 as a matter of expediency pending the arrival of the Tu-14 bomber. While Illyushin and Tupolev both had large aircraft design experience from their own work on twin-engine bombers during the war, Pavel Sukhoi's experience was limited to his prewar tenure at OKB Tupolev. But, given the pace of technological progress and the urgency of rearmament in competition with the West, Sukhoi was ordered on 26 February 1946 to develop a jet bomber powered by four Junkers Jumo 004B turbojets, the same jet engines that powered the Arado Ar 234. Work on Sukhoi's first bomber design began in earnest in April of that year and the aircraft received the official designation of Su-10. 

Several powerplant arrangements were considered along with the use of six engines instead of the four as originally specified. In the Soviet Union, the Central Aerohydrodynamic Institute in Moscow, or TsAGI by its Russian name, did a lot of wind tunnel and theoretical research work to support design efforts at each of the OKBs. At the time that OKB Sukhoi was working on the Su-10, TsAGI had lagged behind Germany and the West in high speed research and as a result, they lacked a significant amount of information on evaluating jet aircraft designs. As a result, much of what laid the basis of TsAGI's high speed aircraft research came about during their work in support of the development of the Su-10 in addition to what had been obtained of German design work following the end of the war. Two leading design variants were evaluated in TsAGI's wind tunnels- one design had four of the jet engines clustered in the mid fuselage and exhausting out the rear with two jet engines under the nose- this was felt to be advantageous design as it left the wings clean. The other leading variant had wing mounted nacelles with a high unswept wing with three engines mounted in clusters on each wing. 

To meet the specified target speed of 528 mph at 26,000 feet, Pavel Sukhoi decided that four engines were insufficient and that six were necessary. Since the Junkers Jumo 004 engine was the only jet engine available to the Soviet Union at the time that had reached production status, the Soviet Politburo placed high priority in reverse-engineering the engine for production- Vladimir Klimov and his OKB were already known for their piston engine designs during the war and he was put in charge of getting the German engine into production as the Klimov RD-10. Klimov's closest aide, Nikolay Kuznetsov, headed the actual reverse-engineering effort- Kuznetsov would go on to form his own engine OKB several years later. 

Inboard layout of the Su-10
With approval from the state authorities to use six engines, design work had settled on a cluster of three engines on each wing as the most efficient layout- the nacelle had two engines side by side with the third RD-10 engine below and slightly ahead of the pair. On 6 May of that year, a full scale mockup was built that was tested in TsAGI's largest wind tunnel with real RD-10 jet engines. Within two months, refinements to the design based on TsAGI's evaluation were in place as full-scale engineering began on the prototype. While two months sounds rapid, development of the Su-10 hit repeated technical hurdles, the biggest of which was that TsAGI lacked a significant portfolio of well-studied high speed airfoils. As a result, while supporting development work on the Su-10, assimilating German design work, TsAGI was also hurriedly developing its on portfolio of high speed airfoils. As a result, Sukhoi's team was constantly having to revise the Su-10 design based on developments from TsAGI. 

By October the full scale mockup had been approved by Soviet Air Force authorities and metal was finally cut for the prototype on 14 October 1946. In the first week of December, the Soviet government commission in charge of aircraft production decreed that the Su-10 would no longer use the Klimov RD-10 engine but instead use the TR-1 engine from the Lyulka OKB, the first indigenous Soviet jet engine design. Since the TR-1 was more powerful than the RD-10, the Su-10 could revert back to a four-engined design and once again Sukhoi and his team had to revise the bomber's design to accommodate the new Lyulka engines. Working at a frantic pace to meet state-decreed deadlines, Sukhoi managed to have a full set of production drawings ready by 23 December 1946 and three days later the OKB's own workshops had completed a static test airframe and production jigs and tooling for the prototype. If things weren't frantic enough as it was, the Minister of Aircraft Industry wanted the Su-10 flying for participation in the air show at Moscow on 18 August 1947! Common sense prevailed and that was one deadline Sukhoi was allowed to ignore. 

Three-view showing the layout of the Su-10 medium bomber
By 15 December 1947 the hydraulic system had been fully tested on a special ground rig (similar to today's "iron bird"), but construction of the prototype was hampered by slow progress from the various subcontractors that were responsible for some of the Su-10's systems. For example, the defensive armament system (which consisted of a manned tail turret, a remotely-operated dorsal turret and forward-firing cannon), the autopilot, the navigation suite and even the Lyulka TR-1 engines were to have all been delivered to Sukhoi's workshops for the prototype but by the end of 1947 none of those items were ready yet. During the delay, studies looked at alternative powerplant options and it was decided that the initial flight tests of the Su-10 would use the TR-1 engine but as soon as the more powerful TR-2 engine developed from the TR-1 became available, the Su-10 prototype would have its engines swapped out and then continue with the flight test program. 
 
These persistent delays led to the Su-10 prototype to sit in the OKB workshops missing various components- by 4 June 1948 the Soviet Council of Ministers ordered that spending had to be reduced on aircraft development programs that year and one of the unlucky programs to get canceled was the Su-10. By that summer OKB Ilyushin had already made the first flight of its Il-28 medium bomber and its performance outstripped what was projected for the Su-10. Not even rolled out, the Su-10 prototype was donated to the Moscow Aviation Institute where it was slowly reduced to parts over time as an instructional airframe. Sukhoi in the years to come devoted its efforts at interceptor, fighter, and ground attack aircraft and it wasn't until the arrival of the Su-24 Fencer in the late 1970s that Sukhoi finally had a production jet bomber. 
Source/Images: OKB Sukhoi: A History of the Design Bureau and Its Aircraft by Yefim Gordon and Dmitriy Komissarov. Midland Publishing, 2010, p93-101.




12 March 2011

The "Wings of Russia" Sukhoi Super Jumbo

The Sukhoi KR-860 was conventional in its layout
At the 2001 Paris Air Show, the Russian delegation created quite a stir by unveiling a four-engine, double-deck, long-haul airliner christened "Kryl'ya Rossii", or "Wings of Russia". The ambitious project had the Sukhoi OKB designation "KR-860"- KR for "Kryl'ya Rossii" and 860 indicating the passenger load. Design work on the KR-860 began in 1997 under the General Designer, Mikhail P. Simonov who had headed the design bureau since 1983. Already under his direction the Su-27 Flanker family of fighter aircraft had been upgraded and new variants had taken flight. By the time that design work began on the KR-860 project, Sukhoi had already been making its first steps into the civil aviation market with the start of work on the Su-80 utility transport and the Su-38 agricultural aircraft. But an aircraft in the class of the KR-860 was nothing short of a bold leap by Sukhoi. The "Wings of Russia" would rival the Airbus A380 and would be larger than the Boeing 747. The design team had looked at advanced technologies and unconventional layouts such as a flying wing, but eventually settled on a blend of advanced technologies (fly-by-wire, composites) combined with a conventional layout with a double deck fuselage and four turbofans. At each step of the KR-860's design evolution, tradeoffs were made between high technology and innovation and low-risk approaches. 

Note the twin nose gear and unusual cockpit fairing
Although the layout of the KR-860 was conventional in appearance, the Sukhoi team succeeded in achieving a predicted lift/drag ratio of 19.5 (compared to the L/D ratio of the Boeing 747 of 17) via aerodynamic refinements. Large winglets were a part of the design and the smooth lines of the double deck fuselage were unusually broken by a blister-like fairing that housed the flight deck. One of the more unusual features of the KR-860 was its use of folding outer wings to reduced the footprint of the aircraft. Boeing had looked at a similar system during the design of the Boeing 777 and had even built a test article, but eventually dropped the idea as the gain in space at the gate wasn't enough to offset the increased weight and complexity. For the KR-860, though, the folding outer wings meant that the aircraft could use any gate position that could accommodate a Boeing 747. While the main landing gear was very similar to that of the 747 and A380 with two inward-retracting wing units and two fuselage mounted units, the nose landing gear was more like that of the Antonov An-124 Condor transport with twin units. The third unique feature of the KR-860 was its three integral airstairs that were on the centerline of the underfuselage- the forward airstair was ahead of the nose gears, the second one was mid-way down the fuselage where the wings were located, and the third and aft unit was under the tail. Like the integral airstairs on the Ilyushin Il-86, these were meant to reduce the ground support needs for the KR-860. 

Note the folding outer wings and the boarding airstairs under the nose
A variety of powerplant options were evaluated for the aircraft- the most serious contender was the General Electric CF6-80E1 used on the Airbus A330 family of aircraft- Sukhoi was reportedly in negotiations with GE at the time of the KR-860's unveiling at the 2001 Paris Air Show. License production of the engine in Russia was even discussed. In addition, consideration was also given to the Rolls-Royce Trent 800 used on the Boeing 777 and the Pratt & Whitney PW4168 used on the A330. In addition, Russian solutions were evaluated from the Kuznetsov NK-93 ducted fan to the unusual suggestion of using eight Soloviev PS-90 turbofan engines in paired nacelles. This would have been the cheapest solution, but the pair nacelles and eight engines would have been significantly heavier and cost more in fuel consumption. 

The aft boarding airstairs under the tail
The eight-engined variant was considered more appropriate for a cargo variant which had an upward-hinged nose visor like that of the An-124 Condor and the Boeing 747-400F. Sukhoi even pitched this version as a successor to the An-124s operated by the Russian Air Force. The cargo version was capable of carrying up to thirty of the 40-foot rail/road cargo containers. Using four turbofan engines, such a version was claimed to have a cost per mile only slightly higher than that of rail transit. In addition, combi versions were suggested and one of the more unusual variants was that of a flying liquified natural gas (LNG) tanker to connect outlying regions in Siberia planned for oil/gas exploration that lacked suitable infrastructure for conventional transport methods. 

Sukhoi estimated the costs for the development of the KR-860 would be more than offset with its use in cargo transport. Costs depending upon the authority consulted ranged from 3-4 billion US dollars to as high as 5.5 billion US dollars. As ambitious as the KR-860 was, there was simply not enough passenger traffic in Russia to justify an aircraft its size. Sukhoi turned to both India and China which had booming passenger markets to explore risk-sharing partnerships. At the end of the day, though, an aerospace project the size and scope of the KR-860 was simply more than both Sukhoi and the Russian government could handle and with more pressing financial needs, the Kremlin was reluctant to invest in the development of Sukhoi's super jumbo. Russian aviation authorities were highly skeptical of the need for the KR-860 given that most of what might get built would be exported to more robust and booming aviation markets. As a result, the KR-860 "Wings of Russia" program died quietly as Sukhoi shifted its resources to a much smaller aircraft that was needed in Russia to replace the aging fleets of Tupolev Tu-134 and Tu-154 fleets. Though development of the Sukhoi SuperJet 100 had started in 1999, the shift of OKB resources from the KR-860 to the SuperJet program which was formally launched in 2002. 

Source: OKB Sukhoi: A History of the Design Bureau and its Aircraft by Yefim Gordon and Dmitriy Komissarov. Midland Publishing, 2010, p501-503.

22 December 2010

How Aleksandr Yakovlev's Rivalry with Pavel Sukhoi Did Him In

Aleksandr Yakovlev
The 1950s and 1960s in Russian combat aircraft development were marked by intense rivalries between the various design bureau (OKBs) heads. Nowhere else was this seen than with the rivalries between the respective OKBs of Artem Mikoyan, Pavel Sukhoi, and Aleksandr Yakovlev. During the Second World War, Yakovlev's OKB was one of the dominant forces in Russian aviation, having built thousands of fighters for the Soviet air forces. OKB MiG (Mikoyan and his partner, Mikhail Gurevich) was rapidly rising to prominence during the war. OKB Sukhoi really didn't start to establish itself until well after the war (some say that Stalin had a dislike of Pavel Sukhoi as one reason). As the jet age dawned, Yakovlev took a conservative approach that saw the first Yak jet fighters as jet derivatives of his wartime piston engined designs whereas MiG and Sukhoi were willing to push the envelope and advance the state of the art. A rivalry between Sukhoi and Mikoyan developed with Mikoyan gaining the upper hand against both Yakovlev and Sukhoi with the MiG-15, MiG-17, and MiG-19 fighter designs which outclassed comparable aircraft from Yakovlev. When in the 1950s the Soviet military command wanted a supersonic interceptor, it was Sukhoi's delta winged Su-9 (NATO code name Fishpot) that edged out Mikoyan's design based on an enlarged MiG-21 fighter. First flying in October 1957, the Fishpot was certainly fast, but it was handicapped by the poor reliability of its Lyulka AL-7F turbojet. In those days, it was rare for an AL-7F engine to last beyond 200 flight hours- and that's not time between overhauls, the reliability of the engine was so poor that few engine units lasted past 200 flight hours, an abysmal figure. The radar set in the conical shock cone of the nose inlet was limited as well. 

Sukhoi Su-9 "Fishpot"
Of course, having the Su-9 having much in common with the Su-7 (NATO code name Fitter) tactical fighter did make selecting the Su-9 for production much easier. But the Sukhoi OKB knew that the Soviet Air Defense Forces (PVO) was not pleased with the performance of the Su-9 and with only 924 examples built, an upgraded Su-11 was introduced. But it would be built in very limited numbers. At the time, the Soviet leadership had decreed that the "missile age" had made many aircraft designs obsolete, and like the infamous Duncan Sandys Defence White Paper in the UK that mortally wounded the British aerospace industry, numerous aircraft and engine projects were canceled and only those designs that were developments of existing designs were allowed to continue to develop. As the Yakovlev OKB had already in production the Yak-25/26 interceptor (NATO code name Flashlight) and attack variants, it proceeded with a supersonic design in the Yak-28 (the interceptor variant having the NATO code name Firebar and attack version being the Brewer). Three features made the Yak-28 more attactive than the Su-9/Su-11 family- first, it used the Tumansky R-11 turbojet was showing itself in the MiG-21 to be much more reliable and durable than the Lyulka AL-7F, secondly it had two engines which gave in a perception of safety over the single-engined Su-9/Su-11 family, and thirdly, having a nose free for a larger radar set than what was possible with the nose intake arrangement of the Sukhoi design meant that production was switched over to the Yak-28 instead, the interceptor version being the Yak-28P. 

Yakovlev Yak-28P "Firebar"
Sukhoi wasn't going to be one-upped by Yakovlev, though. Taking as a baseline the limitations of the Su-9/Su-11 family. OKB Sukhoi set about to create a vastly improved interceptor in the shape of of the Su-15 (NATO code name Flagon). The Su-15 was designed from the outset to be superior to the Yak-28P- it used two of the same Tumansky R-11 engines and used lateral box intakes to leave the nose section free for the same large radar set used on the Yak-28P, the Oryol-D radar. Being a development of the Su-9/Su-11 family, though, it managed to avoid cancellation like so many other projects in the 1958-1959 timeframe in the Soviet Union. Interestingly, the Yak-28P and the Su-15 were produced in the same factory- in the Soviet Union, the OKBs only did design and flight test work with workshops for building prototypes. The designs were then handed off to independent factories for production.  At the time, the Novosibirsk aircraft factory No. 153 was responsible for the Yak-28P production and it was assigned production of the Su-15 once it had passed its State acceptance trials in 1962. Given that both the Yak-28P and the Su-15 used the same powerplant and radar, producing both at the same plant made logistical sense. And there was irony in the decision as the same plant built the Su-9/Su-11 interceptors that were replaced in production at that very plant by the Yak-28P. And now the plant was gearing up to produce more Su-15s with the intent of replacing the Yak-28P with the PVO. 

The sole Yakovlev Yak-28-64 prototype
Not willing to lose out to Pavel Sukhoi, Aleksandr Yakovlev dispatched one of his sons to the Novosibirsk plant to learn as much as he could about the Su-15 design (Yakovlev had two sons who worked for him- one would end up designing the Yak-40/42 airliners and the other would be responsible for the Yak-52 trainer). Seeing the threat posed by the Sukhoi design to the Yak-28P, Yakovlev set about designing an upgraded version provisionally designated the Yak-28-64 (due to work on it beginning in 1964). Many of the features of the Su-15 were incorporated into the Yak-28-64, primarily in moving the Tumansky R-11 engines to the rear of the fuselage from the wings. One of the criticisms of the Yak-28P was that having wing-mounted engines gave the aircraft a poor rate of roll and adverse handing characteristics in an single engine-out situation. Moving the engines to the fuselage resolved these concerns. The tail unit and the wings remained close to that of the Yak-28 and the unique bicycle landing gear was retained. The single ventral fin of the Yak-28P was changed over to a twin ventral fin arrangement for stability. Given that OKB Yakovlev had little experience with fuselage-mounted lateral intakes, Yakovlev incorporated a copy of the Su-15's lateral box intake design on the Yak-28-64. 

Yak-28-64
The prototype Yak-28-64 was rolled out in 1966 and it proved in flight tests right off hand to be a dog. In fact, the Yak-28-64's performance was even worse than that of the Yak-28P, the very aircraft that was being superseded by the Su-15. Numerous unpleasant handling characteristics were also uncovered and some of the landing issues present in the Yak-28P thought to be cured in the Yak-28-64 persisted (such as aileron reversal at high speeds). It didn't take long to realize that the Yak-28-64 was a dead end and the project was abandoned by Yakovlev. 

Sukhoi Su-15 Flagon
A look at some of the production figures during this rivalry is telling. Just over 900 Sukhoi Su-9s were built at the Novosibirsk factory. Less than 100 Su-11s were built. Replaced in production at the factory by the Yakovlev Yak-28P, over 400 examples were built before it was completely supplanted by production of the Su-15, of which over 1,200 were built. The attack versions of the Yak-28 had to be continually upgraded with no less than 10 versions, each in relatively small production batches around 200 or so. Having been topped by Sukhoi in the interceptor arena with the Su-15, the Soviet air forces replaced the attack versions of the Yak-28 with another Sukhoi design, the Su-17/Su-22 family (NATO code name Fitter) which proved more reliable and versatile operationally. 

The Yak-28-64 and the rivalry with Pavel Sukhoi damaged OKB Yakovlev for good. His designs were considered by the Soviet air forces to be unreliable and obsolete, at the worst, limited in performance at best. For years no other Yakovlev combat aircraft design was taken seriously by the Soviet military high command and even the VTOL Yak-36 design was supremely limited in its utility. Even Yakovlev's submissions to the  competition that resulted in the MiG-29 Fulcrum and the Sukhoi Su-27 Flanker (Yak-45 and Yak-47, respectively) were decidedly archaic in appearance and failed to use some of the latest advances in aerodynamics. Most Yakovlev designs following the abandonment of the Yak-28-64 were either light aircraft or airliners, areas that were more heavily influenced by his sons than by Aleksandr Yakovlev himself. 

Source: OKB Yakovlev: A History of the Design Bureau and its Aircraft by Yefim Gordon. Midland/Ian Allan Publishing, 2005, p215-230. Additional material from Paul Martell-Mead at the Secret Projects forum. 


17 December 2010

Soviet Wild Weasels: Part Two (Aircraft)

Yakovlev Yak-28PP "Brewer-E"
Last night we took a look at the nuts and bolts of Soviet suppression of enemy air defenses (SEAD) doctrine and tactics. Tonight we'll continue along that them with a look at the aircraft that filled the role of  "Wild Weasels" in the Soviet air forces. Like the United States, the Russians had put into service several specialized aircraft that were used to knock out and/or jam enemy radars and surface-to-air missile sites. These aircraft were based upon established production types much in the same way the USAF Wild Weasels were adaptations of production fighter aircraft. The first aircraft to fill this role was the Yakovlev Yak-28N, an experimental adaptation of the Yak-28 "Brewer" attack aircraft. This version of the Brewer was the first Russian development for a Wild Weasel-class aircraft; work began by OKB Yakovlev in 1964-1965 with a production Yak-28I being set aside in 1965 for conversion to the -28N configuration. The attack Yak-28I had the "I" suffix as it was equipped with the Initsiativa-2 ground-mapping/bombing radar in a ventral radome aft of the nose gear. On the Yak-28N, the Initsiativa-2 radar was replaced by radar pulse detection unit that would seek out and locate enemy radar emissions and provide targeting data to Raduga Kh-28 (NATO code name AS-9 "Kyle") missiles, one each under the outer wings. The Kh-28, which I'll discuss in a subsequent post, was the first Russian anti-radiation missile to be fielded with the first operational examples coming out in 1964. 

By the time operational testing of the Yak-28N was completed around 1972, it had been far outclassed by contemporary Russian and American designs and the project was canceled. However, the work that had been put into the Yak-28N wasn't wasted as the Soviet air forces still needed a battlefield electronic warfare aircraft that better performance and was more flexible than the existing design in use, the Tupolev Tu-16PP Badger which clearly by 1972 was too big and too slow to survive in hostile airspace. The Yak-28 was again used as the basis for the Yak-28PP electronic warfare aircraft that crammed the jamming equipment of the Tu-16PP into a much smaller airframe. All of the armament provisions of the Yak-28 were deleted and four different jamming systems were installed in the Yak-28PP, which was marked by a number of dielectric bulges and blisters on the fuselage. The jamming systems generated so much heat that two heat exchangers were installed in the lower aft fuselage ahead of the aft bicycle gear to help cool the avionics. The outer wing pylons were fitted with rocket pods that fired chaff ahead of the aircraft to help sow chaff corridors to protect inbound strike packages. Below each engine nacelle of the Yak-28PP was a system for deploying bundles of fiberglass-based chaff strips in mass quantities. The role of the Yak-28PP was to accompany inbound strike packages with three of the ECM -28PPs sowing a chaff corridor on each side of the strike aircraft formation as well as using its powerful jamming equipment to blind NATO air defense radars. The first Yak-28PPs completed their State acceptance testing just as the Yak-28N was canceled. Most of the Yak-28PPs that were built (NATO code name "Brewer-E") were based with the Soviet forces in East Germany. 

MiG-25BM armed with Kh-58 missiles
The cancellation of the Yak-28N in 1972 came about due to the arrival of an aircraft with significantly higher performance that would become the first Russian production Wild Weasel-class aircraft, the Mikoyan MiG-25BM "Foxbat-F" based on the production interceptor version. It was recognized early on in the Foxbat's flight test program that a high-flying, high-speed aircraft would make an ideal SEAD aircraft- as it was proved itself immune to interception during operations over the Sinai prior to the Yom Kippur War, a SEAD Foxbat could out-fly defending fighters, fire its anti-radiation missiles, and streak back with impunity. While early anti-radiation missiles like the Kh-28 mentioned already were heavy, the newer generation of anti-radar missiles like the Raduga Kh-58 (NATO code name AS-11 "Kilter") were much lighter and imposed little performance penalty on the Foxbat. 

Mikoyan MiG-25BM Foxbat-F in East Germany
At first the MiG-25BM was to be a dual-role reconnaissance/SEAD aircraft, the concept being that it would use its SEAD capability to allow it to penetrate deep into NATO airspace to complete its reconnaissance mission. By 1977 both the Soviet air forces and Mikoyan realized that the aircraft would be compromised in both roles and different Foxbat variants were developed for each role, with the MiG-25BM being the definitive SEAD variant. The MiG-25BM featured an integrated avionics package called Yaguar (Jaguar) that not only detected and located enemy radars, but it also networked with the Yaguar systems of other MiG-25BMs to allow a "wolf pack" of SEAD Foxbats to operate deep into NATO territory and share data and targeting information with other members of the wolf pack. The Yaguar system included target designation functions that cued the seeker heads of the four Kh-58 missiles that the MiG-25BM carried. In addition to the missiles, nuclear warheads could also be delivered to either knock out SAM missile sites or generate an EMP to short out communications and electronic systems. Several internal active ECM jammers were also carried which not only protected the MiG-25BM from air defense radars but could also counter fighter radars as well. The Foxbat-F was in production from 1982 to 1985, but the complex systems of the aircraft meant that only 40 examples were built. Nearly most were assigned to units stationed in East Germany and were unusual in being the only Foxbats to wear camouflage as the reconnaissance and interceptor variants were gray in color. Despite production ending in 1985, continued technical problems that had to be resolved meant that the first MiG-25BMs weren't operational in East Germany until 1988 with the Group of Soviet Forces Germany (GSFG), which ultimately withdrew from German soil in 1994. 

Kh-58 missile on an Su-24M, Fantasmagoria pod below it
The last SEAD aircraft developed for the Soviet air forces was the Sukhoi Su-24M "Fencer-D", but by this time the Fencer-D was less an dedicated SEAD asset and more an attack aircraft that had SEAD capabilities. Unlike the Yak-28N and the MiG-25BM that housed a large amount of equipment internally, technological advances meant that the Fencer-D could carry most of the radar detection and location equipment in a pod mounted on the centerline underfuselage which was called Fantasmagoria, with -A, -B, and possible -C version depending on the internal configuration of the pod. This was similar to the USAF where the Lockheed Martin F-16CJ replaced the specialized F-4G Phantom Wild Weasel. The F-16CJ had a small pod called the HARM Targeting System (HTS) that performed the same role as the Russian Fantasmagoria pod. The Su-24M could carry two kinds of anti-radiation missile, either the Kh-58 as was used by the MiG-25BM or the newer Kh-31 (NATO code name AS-17 "Krypton") missile. 

Sukhoi Su-24M Fencer-D, note the Fantasmagoria pod
The closest that Russian SEAD aircraft came to being committed to action came during the Soviet invasion and occupation of Afghanistan fron 1979 to 1988. During the war, Tupolev Tu-16 Badgers were used to bomb Mujaheddin positions, but were often tracked by Pakistani air defense and early warning radars. It was proposed to use the Su-24Ms to knock out the Pakistani radars which were providing warning information to Mujaheddin forces, but it was realized that it represented a significant escalation of the conflict and only limited cross-border raids were conducted with SEAD protection. During the Russian-Georgian War of 2008, it is believed that Su-24Ms were used against Georgian air defense positions, but poor tactical coordination resulted in the Georgians shooting down two Fencers. 

The last installment of this series will take a closer look at the anti-radar missiles that the Russians fielded for their SEAD assets. Stay tuned!

Source: Wild Weasel Fighter Attack: The Story of the Suppression of Enemy Air Defences by Thomas Withington. Pen and Sword Aviation, 2008, p100-102.