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Su-27: Russia's Top Fighter of the Cold War?

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Su-27: Russia's Top Fighter of the Cold War?
By Iain Norman
Oct 7, 2003, 18:30

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When discussing all the fighters produced by the Soviet Union it seems as though the words ?best? and ?Flanker? go together much too easily. The general view that the top fighter created by the Soviets for use during the Cold War was the Sukhoi Su-27 seems to be firmly implanted in the minds of the general public. Some, however, defend a different view; that of the most useful aircraft built for the purpose of shooting down the F-15 and F-16 was not in fact the Su-27 or the MiG-31 (its role being confined to cruise missile and bomber interception) but the MiG-29. Many will be quick to point out its faults so for the purpose of giving the reader a chance to compare the two (Su-27 and MiG-29) it would be in order to outline some of the generally acknowledged strengths and limitations of the respective aircraft.

Strengths of Su-27:
- long endurance
- heavy armament, including up to six R-27 (R-27R/R1, R-27ER, R-27T/ET)
- reasonably good sensors with a long-range radar
- excellent maneuverability

Weaknesses of MiG-29:
- very limited range
- carries a maximum of only two R-27s (R-27R/R1), which it is not likely to use due to weak sensors, and heavy reliance on GCI
- weak processing capability and vulnerability to any kind of jamming

If one takes all the above at face value it would seem that there is no ground for an argument. The Su-27 appears to be a wonder fighter and the MiG-29 a very limited airplane. On a second view many of these ?common attributes? of the Su-27 are in fact meaningless or simply very limited in their meaning. Let us take them one at a time.

Range It should be said from the start that range is indeed a true attribute of the Su-27, but with its undoubted strength come many weaknesses; one of the main tradeoffs is the weight penalty. This translates into poor maneuverability which will be discussed in detail in the next section. However what it basically amounts to is that the Su-27 cannot achieve AoA and G level close to those of the MiG unless it is carrying only 60% of its maximum amount of fuel. Which gives of course a much smaller range if the mission profile calls for the possibility of having to maneuver during the flight. In an all out scenario of war over central Europe the general chaos of the situation could well mandate such a requirement. At 60% fuel load and Su-27?s maximum range is (assuming an optimal range profile of Mach 0.8, 13,000 m) roughly 1860km. This takes into account 400kg of fuel for startup, taxi, and takeoff procedures, 1100kg for the climb, and 370kg for reserve.

The MiG-29 most assuredly is a very limited range aircraft but this fault was rectified to some extent in the MiG-29 Fulcrum C (9.13) which added a so-called ?hump back? saddle style fuel tank on the spine of the plane. This hump contained more fuel and an active jammer, offsetting probably the most valid of the concerns about the plane. However most of the room created by the spine was taken up by the jammer and the amount of fuel (translated to little extra flight time. But an increase however slight was still, to some extent, useful. One also has to consider that the intended role of the MiG-29 was that of ?battlefield air superiority?, and thus was not intended to undertake long combat patrols but rather to be more of a defensive interceptor. The MiG-29 carries less fuel, but is also smaller and far less probable to be seen from long ranges like the Su-27; when used in its intended role and with designed support, MiG-29?s disadvantages are also not as bad. A MiG-29 Fulcrum A (9.12) carrying a centerline fuel tank will need 400kg of fuel for startup, taxi and takeoff, 500kg for a engagement (including one minute of afterburner) and will usually need to have 1,000kg reserve for the return to base. This will leave 2,500kg of fuel for operations: enough to travel 408nm at Mach .8 at 40,000ft with five minutes loiter time. From the bases in East Germany this would be enough to get over southern England. Or to put it another way, at the optimal range profile (Mach 0.8, 13,000 m) assuming expenditures of fuel for startup, taxi, and climb to 13,000 ft at roughly 1180kg, the MiG is left with 2100kg for flight. Assuming that the peak of the decent to land back at the airfield is made roughly 100km out and at idle power, the maximum range of the MiG-29 (at Mach 0.8) is roughly 1450km. With the centerline tank that becomes 2090km.

Thus carrying the centerline tank the MiG-29 can actually out range an Su-27 at 60% fuel. Now of course the tank does impose some constraints on the MiG. However it would be emptied first before the internal tanks and then dropped. It should also be said that the Soviets would have operated their Su-27s with more than 60% fuel to allow for startup, taxi, takeoff, and climb procedures giving the Su-27 pilot 60% when he reached his preferred altitude.

Maneuverability Both of these planes are famous for their maneuverability, their designers went to great lengths to insure superior maneuverability dow to the last10% of their performance. The MiG-29 in particular wears the crown of ?the most maneuverable aircraft in the world? according to many opinions. This is a true virtue of the plane, and in general one sees the MiG much less overrated than the Su-27. The MiG was designed for maneuverability at slow speeds (below 350 kts) and it is acknowledged by F-16 pilots that it is much more maneuverable than their own highly agile mounts in this flight regime. This slow speed maneuverability allows the plane great ability to point the nose. In conjunction with the HMS (Helmet Mounted Sight) and the R-73, this offers huge advantages in the capability to point the plane towards the potential target and to snap a missile off. In this arena, the MiG-29 constitutes a highly potent threat.

The Su-27 on the other hand cannot achieve full AOA and G ratings until internal fuel has been reduced to 60% ( (assuming that the maximum fuel load has been carried), meaning that a long range mission must account for not being cappable of efficent close-range combat until 40% of the fuel has been used. The technical reasons behind this limitation are simple; when fuel is reduced to by 40% the No.1 fuel tank, located behind the cockpit, and the No.4 tanks, located in the wings, are emptied. The importance of this lies in the No.1 tank which when full has an adverse affect on the plane?s center of gravity, moving it forward of the optimal balance. Thus when it is emptied the plane?s manvering cappabilities rise sharply. This fact means that the mission planning has to be very precise when it comes to the fuel ? which is easy during training, but something almost impossible under real combat circumstances. In the case of any kind of unplanned engagements the plane has to get rid of fuel overload; jettisoning BVR missiles is also a very real possibility as they constitute a weight and aerodynamic penalty. Only once the Flanker is lightened to a certain extent it is highly maneuverable. However the Su-27 does possess an analog fly-by-wire system, something not employed by the MiG-29.

BVR (Beyond Visual Range) Capability The main BVR weapon of both types is the R-27 (AA-10 Alamo), a missile actually specially developed for the Su-27. The Su-27 can carry a maximum of up to ten R-27R/R1/ER/T/ETs, while the MiG-29 can carry a maximum of two R-27R/R1/Ts.

Clearly, the armament of the Su-27 is much heavier, but the question is if this is actually as important in modern air warfare and how does this amount to in a fast moving engagement? Not that much. First of all it should be mentioned, that modern fighters do not have much time to use their weapons, nor are they likely to confront dozens of opponents. Modern air combats are characterized by their high speed and short duration: the results of the engagements are usually decided after the first exchange, and the subsequent loss of the situational awareness means that pilots from both sides will try to disengage in order to avoid being surprised by so eventually undetected enemy. The N-001 and the N-019 are heavily specialized for exactly this kind of engagements: they are mechanically scanned arrays they can only illuminate one target at a time, which in turn means that only one target can be engaged by SARH missiles. This brings to bear grave concern on validity of carrying a full load of six SARH missiles, as the aircraft is almost 95% sure to be able to attack only one target per mission. Thus the superiority in the number of weapons the Su-27 can carry is questionable, to say at least: it is not likely to engage more than one target per mission, it will carry the same mix of IR guided R-27Ts or R-27ETs as well as the R-27Rs and R-27ERs, but is very likely to be overloaded with weapons which it is not likely to use.
Due to their guidance system of homing onto the heat emissions the T and ET are fire and forget missiles. But they have major disadvantages: they do not possess a data link like SARH verstions, which means they can only be fired when the actual missile seeker is locked onto the heat emissions of the target. This severely limits the range that the T and ET can be launched at, despite their aerodynamic capabilities, and their powerfull motors. Also it is important to note that the range for detection with the radar drastically decreases in a tail-chase. So the R-27T/ET are really only useful in a tail-chase were the performance of the SARH missiles falls off and the IR homers have better range than in a head on aspect (this better range is due to the fact that the heat emissions of the target are much more prominent to the rear of the plane which, in a tail chase, would be facing toward the Su-27). So in reality, a combination of the two homing methods would be to the plane?s advantage: such combination is given on the MiG-29 as well as on the Su-27, but with the difference that the MiG-29 is more likely to engage at combat weights, and the Su-27 far more likely to be at overweight and within stress limitations at the moment of the first engagement. With other words: the MiG-29 will probably be ready to engage straight away, the Su-27 might need some precious time before the pilot will consider the condition ? especially the weight factor ? of this aircraft appropriate.

The MiG-29 can only carry two missiles, but it is standard practice ? and a part of the training schedule - no matter what combination of R-27s is carried, to fire them at the same time and against the same target. This was due partly to having the problem of a unbalanced plane if one was left under one wing while the corresponding station on the other wing was left devoid of a R-27, which severely limits maneuverability (15? AoA instead of 24? AoA). In theory, the Su-27 behaves like a gunslinger: under ideal circumstances - and if its opponents would be kind enough to wait - it could engage up to three of them, one after the other, each with a pair of R-27R and R-27T. In practice, the opponents do not wait: either they engage (which brings them closer), or disengage (which distances them outside the missile envelope). So, the Su-27 is very likely not to be in condition to need all its theoretical armament. The MiG-29 will engage and fire only its single pair of R-27s. An added benefit is that the plane is immediately afterwards ready for a combat at closer ranges, and there is no question of dumping fuel or jettisoning weapons.

Radar Concerns The basic performances for the radars of the Su-27 and MiG-29 - i.e. detection ranges (all range figures are for a 3sq m target)
- N-001 (Su-27): 80-100km head-on and 40km from the rear
- N-019 (MiG-29): 75-85km head-on and 35km from the rear

Both radars can track ten targets and engage one at the time with R-27R missiles. Both operate in the 3cm wavelength, azimuth limits for the N-001 are +60? -60? and +67? and -67? for the N-019. Both radars have the ASCC designation ?Slot Back?. Both have twist-cassegrain antennas and are pulse-doppler designs. The N-001 has a definite range advantage, but both radars use the ts100 processor, which can perform 170,000 operations per second, so the Su-27 can claim no advantage in this area. It is interesting to note that while the Su-27 has a 15km range advantage (using the upper range figures or the lower figures) in the head-on aspect there is only a 5km range difference in the tail-chase aspect. Both radars have much in common, upwards of 70% of the components are shared (the exact figure has not been disclosed). The radars were a source of disappointment for both aircraft, much more advanced designs had been projected but the poor state of the Soviet electronics industry prevented this and older technology (namely the twist-cassegrain antennas) had to be used. The Su-27?s projected radar in particular was troubled, and the N-001 is basically the N-019 scaled up to fit the larger radome of the larger plane.

GCI (Ground Control Intercept) Reliance The heavy use of ground control interception radar stations by the Soviets was a policy well in place by the time the Su-27 and MiG-29 entered service. It was often criticized by the West as not allowing flexibility in a flight and limiting the freedom of the pilot. All in all it was a technique that was thought to create pilots that were more reliant on GCI than on their own personal skills. While in fact the role of GCI was pretty similar to that of a Western AWACS -i.e. to provide advanced warning of and advice for how to engage targets ? while introducing the MiG-29 and Su-27 into service the Soviets started developing their interception doctrines so to provide their pilots with the ability to operate autonomously. This is less so the case with the MiG-29, and slightly more with the Su-27: the MiG-29 was especially branded with the label of ?GCI dependency?, but given the same basic radar technology and capabilities, this argument is actually irrelevant. Regardless if flying the MiG-29 or the Su-27, the pilots are trained to operate their radars powered up but not emitting (in the ?standby mode?), then wait for the report from the GCI that their assigned targets are in range, and they should activate the radar: similar decisions are made solely by the pilots in western air forces. It is of extreme interest to note here, however, that Frontal Aviation (FA) pilots thought of their fellow pilots in the PVO, (the Soviet home defense air force) in a derogatory manner, as being heavily GCI reliant: in expectation of massive encounters with NATO fighters, the FA recognized that its GCI system could not properly track large air battles and would very likely lose the control of the developments. Therefore, the pilots were trained to make many of important decisions alone ? just like their counterparts in the West. The PVO-pilots, however, were expected to intercept singular bombers which would try to penetrate the Soviet air space. Their GCI was likely to remain in control of all the developments for 99% of the time. Therefore, the PVO-pilots were trained to exactly follow the orders from their GCI.

Conclusion Given the above facts, the MiG-29 seems to have a small advantage, in as much as it is a ?to do? type of aircraft: it is built to be scrambled, close at high speed and launch an attack against a single target using R-27s. If needed, the plane could then relay on its maneuverability and snap-shot capability to repeat the attack from a closer range. The Su-27, on the contrary, can be seen as a kind of a further development of the MiG-29, and is at best described as a flying SAM-site. Especially the ability to carry a large number of R-27R/ERs and T/ETs (the ER and ET are slightly improved versions of the R and T, respectively, which have improved motors enabling them to engage targes at higher speeds; nevertheless, their engagement envelopes remained the same). But, there is a huge problem that the Su-27 was developed in context with the Cold War. Without any surprise, it is constantly being redesigned ever since.

First of all the original design for the Su-27 (built in 1978) was unsatisfactory so a redesign was required. This was the T-10S. The first production Su-27S were to be delivered in 1984, but due to many problems with the plane as a complete weapons system delivery was delayed until 1985. Even these first twenty planes were only delivered to a test squadron by the production plant. Many additional problems then plagued the test unit, the avionics proving to be a major source of trouble. During 1985 the deliveries continued, and by 1989 a few hundred Su-27s were is service. But the system was only accepted as fully combat capable in 1990, showing that even in the period between 1985 and 1990 huge problems with reliability and the avionics existed. By contrast the MiG-29 had a remarkably smooth development and the integration of radar and avionics went very well in comparison.

In conclusion, it is obvious that one cannot possibly consider the Su-27 in a realistic light as it was not accepted into full service until 1990; by which time the Cold War was in all practicality over! With other words, while the Cold War was in full swing ? in the mid to late 1980s - the MiG-29s of the 16th Air Army in East Germany were expected to do the job alone and without any help from Su-27s. The 16th Air Army was feared by NATO forces, and had the best pilots in Frontal Aviation service. An above average collection of pilots flying an above average machine; the best their country had to offer. As such, in Soviet service at the time, the MiG-29 was certainly a much more valuable combat system in that it arrived on time where as the Su-27 took far longer and in fact emerged in regular unit service only in the last years of the Cold War.

Ever since however the further developments of the Su-27 continue to fascinate the public.

Sources

ACIG Forum

MiG-29 Flight Manual by Alan R. Wise

Su-27 Flanker Story by A. Fomin

MiG-29 Flight Manual Russian edition

Special (and grateful) thanks to ?Booga? for access to some source material and calculation assistance.