Russia’s Su-57 fighter program – it’s worth following

If you’re not following the Su-57 because you rightfully believed that Russia was not going to procure these aircraft in sizable numbers, that the program was in limbo, or that this aircraft’s potential didn’t add up to much, now is a good time to take a second look. I think a fair bit of commentary and writing has been overly dismissive of this program based on earlier prototypes shown, and does not account for the different design philosophy and missions in mind that Russian MoD had behind the Su-57 when compared to U.S. approach to 5th generation aircraft. It’s also worth noting changes taking place to the design as it begins to mature.

I rarely write about aerospace and will walk into this subject cautiously.

BLUF: The Su-57 is a high maneuverability air superiority fighter, with a substantially reduced radar cross section compared to 4th generation Russian fighters, designed to work as part of Russian air defense to counter stealth aircraft near or within Russian airspace. This fighter is meant to team with Russia’s sizable 4th gen air force, and VHF/UHF ground based acquisition radars, to establish local qualitative advantages and help close corridors in Russian air defenses. The Su-57 is an affordable, producible option to bolster Russia’s air defense network. It will pose a major challenge for any 4th gen aircraft, and concern to stealth optimized 5th gen aviation. Yes it is a stealth 5th generation aircraft, but it is not a F-22 or F-35 clone, and the design philosophy is not based around mission requirements similar to U.S 5th generation aircraft. This fighter is tailored to Russian needs, though it has features intended to make it attractive to an export market.

Putin looking at Su-57

On May 15th Vladimir Putin announced that Russia would sign a contract for 76 Su-57 fighters, this will buy three regiments of 24 aircraft, plus a flight of 4 possibly destined for Lipetsk combat training center. The actual contract is likely to be signed at MAKS-2019 show late August. According to Kommerstant the contract is valued at 170 billion RUB (this figure is too low), which will fully load the production line at Komsomolsk-on-Amur plant, though at a rather low profit margin of 3-5%. This plant is already busy with Su-35 orders. Alongside the Su-57 announcement, Putin also declared that a contract will be signed in 2020 for 100 Mi-28NM helicopters and 114 Ka-52M helicopters (Ka-52M variant to be created by 2022). The Su-57 buy appears to be scheduled for 2019-2028, though keeping in mind that the state armament program for 2018-2027 is revised every five years, so in 2022 there are likely to be course corrections.

Putin remarked that Russia has bought more than a thousand fixed and rotary wing aircraft 2011-2018. This is true, about 468 fixed wing tactical aviation and somewhere around 600 helicopters (I’ve not found exact figures for helicopters). The original state armament program (2011-2020) hoped to buy 52 serially produced aircraft. After 2015 the timeline began slipping to the right, and the expected order size drastically reduced. The expected order dropped to 15 aircraft by 2028, with earlier explanations from Deputy Defense Minister Yuri Borisov that can be summed up as ‘Russia’s 4th gen aircraft are perfectly fine for our requirements so we don’t need Su-57 right now.’ This suddenly changed last week to ‘we’ve not built anything like this platform in 40 years and are going to invest in 5th gen. Such a reversal is not uncommon in Russian defense practice. Russia’s purchase of 76 aircraft is considered an initial installment, Russian air force requirements were considered to be 200-250 Su-57s. Considering the aerospace sector’s performance 2011-2018, they could readily build in the 2020s once serial production is established.

Russian aircraft procurement 2008-2017
From BMPD and Anton Lavrov’s work. Peak production years 2014-2016 for the main programs, though Su-34 remains in strong demand. Production has declined while overall procurement spending has remained relatively flat, demonstrating a limited appetite for purchases in this sector beyond certain aircraft.

Background

Su-57 is the official designation of the aircraft developed under the PAK-FA program (Перспективный авиационный комплекс фронтовой авиации), so far producing 11 prototypes, marked T-50-1 through 11. The USSR conducted research into low observable aircraft in response to the U.S. Advanced Tactical Aircraft program, yielding technology demonstrators such as the Mig-1.44 and the S-37. In 2002 Russia and India agreed to jointly develop a derivative of the PAK-FA aircraft as part of the Fifth Generation Fighter Aircraft Program (FGFA) for India. The deal was signed in 2010, with an initial investment of $295 million to jointly develop the design between Sukhoi and India’s HAL. The overall program was valued at $6 billion, with 35% allocated to Indian enterprises. In 2012 work stalled due to disagreements over financing and technology transfer. Moscow sought $5 billion from India to continue working on the program, valued at $10 billion. An arrangement was supposedly  worked out in 2016 envisioned both sides investing $3.7-4 billion into the program over 6-7 years.

Mig 1.44 demonstrator

Mig-144

India sought more than 50 modifications to the aircraft, ranging from engines to stealth characteristics, meanwhile HAL’s role in the program declined to 13%. Delhi kept changing its mind about how many, and what type of FGFA aircraft they intended to procure, originally seeking 214 fighters with 48-66 of them modified two-seat versions. Subsequently Indian requirements changed to 144 single-seat fighters, and were further reduced to 127. In early 2018 India walked away from the program citing shortcomings in stealth and avionics. Some Russian analysts interpreted this decision as the result of the technical and financial disagreements, along with Indian disappointment that they were not going to develop the Indian 5th gen aircraft they wanted on the basis of the Russian PAK-FA. Other sources suggest that Moscow wanted India to fund at least half of the R&D, but Delhi had already spent an estimated $8 billion on 36 Dassault Rafales (in a deal mired in controversy), and essentially had no money in the procurement budget to seriously invest in FGFA.

Instead India was to receive an export version of the T-50, and in this scenario they backed out, leaving the development risk to Russia, with the option to come back and buy the Su-57 if Sukhoi proves successful. Why India believed they could co-develop a 5th generation aircraft program with Russia, gain experience and tech transfer, for a fraction of what similar such programs typically cost, remains a mystery. Similarly, some Western analysts and commentators began writing off the PAK-FA when India backed out, as though the $4 billion that Russia never actually received from Delhi was going to make or break Russia’s 5th generation program (a country that spends 1.5 trillion RUB on R&D and procurement per year). Many of these predictions of Russian next gen weapons programs entering ‘death spirals’ are simply wrong.

Reasons for the delays found in defense news articles typically reference something about a lack of money, sanctions, or other analytical spaghetti thrown at the wall. There is no evidence that the PAK-FA program suffers from these problems. A simpler reason is that developing a 5th generation aircraft is not all that easy especially if you’re integrating a host of new capabilities, from an AESA radar, to a low observable air frame (or at least an attempt at one), a new engine, flight control system, etc. Suffice it to say Sukhoi encountered challenges – here are a few visuals to illustrate:

that's a problemmore problems

Aircraft cost

It is difficult to talk unit cost because the aircraft is being bought in two phases, one with the AL-41F-1 engines and another with the Izdeliye 30 engine, which is currently undergoing testing. Since key components for the real Su-57 are not yet completed, it is challenging to estimate the actual price per unit. Currently it is estimated as a $2.5 billion USD program which works out at ~$35 million per aircraft. That seems deflated and cheaper than the Su-35, i.e. it just can’t be true. Ilya Kramnik at Izvestiya expects the overall cost of the program to be 400-500 billion RUB, as opposed to 170 bil RUB, which would make the recently announced price tag reflective of just the initial batch of serially produced aircraft. Plus United Aircraft Corporation is going to haggle over the relative price of all the aircraft it is building for the MoD such that the ultimate price per aircraft is going to only be tangentially related to the actual production cost. Most of the estimates on price seem to cluster at $45-54 million USD, or about half the cost of a F-35, not that everything should be measured in prices relative to U.S. acquisition programs.

As I have argued in earlier articles, based on purchasing power parity (PPP), as opposed to pointless conversions into average USD currency values (the kind offered to us by SIPRI), Russia spends roughly $150-$180 billion in overall military expenditure. Of this about 75% is the national defense order, with roughly 50% of that budget allocated to procurement and R&D (maybe an effective $50-$60 billion). This aircraft will have a USD based export price tag at some point, but the cost to the Russian defense budget needs to also be understood in terms of effective spending value, calculated based on PPP. This is a domestically produced aircraft, which thanks to Western sanctions, is going to be made with probably almost entirely Russian components, especially after India withdrew (not that HAL was going to do much anyway). At 2.3-2.5 billion RUB per aircraft the program works out right now to an effective $80-100 million of spending per unit produced.

Aircraft design and purpose

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I think the Su-57 is a misunderstood aircraft in terms of design philosophy, purpose, and program viability. The Su-57 is a compromise between reducing the radar cross section and building a highly maneuverable air superiority fighter, with great performance at high speeds, and at different altitudes. It has innovative features which should qualify it for the 5th gen moniker, some of which I will cover later in this piece (engine, flight control, sensors, materials, etc.) That said, the Su-57 does not represent an aircraft solely dedicated to stealth and beyond visual range combat on the basis of first look/first kill.

The Su-57 is not necessarily intended to compete on stealth with U.S. F-22/F-35, though depending on the aspect, it may be quite comparable. It is not meant for penetrating integrated air defenses, conducting deep strike missions, or conducting offensive counter air within enemy air defenses. To compare its design for such roles is to engage in mirror imaging. The Su-57 appears intended to engage enemy stealth aircraft within its own air defenses, guided to target by ground-based low frequency radars, leveraging its own low observation properties to get closer to the adversary, and a mix of on-board sensors that can help with detecting low observable aircraft once within close range (IRST). I suspect it is intended to plug gaps or corridors in Russian air defense that may exist for very low observable aircraft.

The Su-57 has a SH121 multi-functional system consisting of N036 Byelka radars, which feature five active electronically scanned array radar antennas. Three in the X-band, one primary nose mounted, two smaller radars in the cheek position, plus two L-band matrices in the wing edges. Those can be used for IFF and electronic warfare, probably not powerful enough for any real stealth search/detection capability. Between the five AESA antennas, and the dedicated ECM suite in the tail, the Su-57 should be a capable electronic warfare platform, and leverage EW strengths to compensate for any shortcomings in stealth. The fighter could be used to establish local areas of air superiority against 4th gen aircraft, and get close enough to a stealth optimized aircraft to become a problem, especially with passive forms of detection like IRST. The Su-57 can carry the latest generation of Russian standoff strike weapons, and may have a role in intercepting high value air assets as well, such as AWACS. It has already been shown firing a Kh-59MK2 air-to-surface standoff guided missile.

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There was no discernible Russian desire to build an advanced sensor fusion platform that could integrate with a other ISR infrastructure, or for the aircraft to serve as an ISR platform for the rest of the force. They were not seeking a stealth optimized strike and recon platform for penetrating strikes. On the whole, there is considerable doubt in Russian circles on the viability of stealth in general, and a strong belief that aircraft must retain high performance flight characteristics – including so it can survive in a post-stealth world. Russia deployed low observable cruise missiles well before the Su-57, and in general, there is stronger interest in making long range guided weapons low-observable rather than planes. There is some suggestion this plane will team with Okhotnik-B or prospective drone platforms, but that may be aspirational at this stage. The potential Su-57 pairing with Okhotnik-B is unclear, but the Russian drone is remarkably large, and may offer an additional sensor suite for queuing.

Okhotnik and Su-57 on display
Recent photo of Okhotnik-B compared to Su-57 and other aircraft

From a stealth perspective, there are problems with the airframe design as is, but these were conscious choices by the designers. It has features of a high altitude interceptor, maneuverable dogfighter, and effort was made towards reducing the RCS via shaping compared to previous Russian 4th gen fighter designs. The patent filed acknowledges that the core requirements were a contradiction (that never happens in acquisition programs!), therefore the aircraft is inherently a compromise. The fighter features maneuverability at high angles of attack, great aerodynamic performance at supersonic speeds, and good aerodynamic performance at subsonic speeds, supercruise in the final engine, an internal bay capable of large payloads, and a substantially reduced radar cross section probably in the .1-.3m² range just based on shaping. When factoring in radar absorbing material, radar blockers, etc. it could be quite lower than .1m² and grant the aircraft very low observability.

Patent text for those interested:

“Изобретение относится к многорежимным самолетам, эксплуатируемым на сверх- и дозвуковых скоростях полета, в широком диапазоне высот полета. Преимущественная область применения изобретения – многорежимные сверхманевренные самолеты с крейсерским полетом на сверхзвуковой скорости и малым уровнем заметности в радиолокационном диапазоне.

Создание самолета, способного выполнять задачи в широком диапазоне высот и скоростей полета, обладающего возможностями сверхманевренности и, при этом, имеющим малую заметность в радиолокационном диапазоне длин волн, является сложной технической задачей.

К аэродинамической компоновке такого самолета предъявляются требования максимизации аэродинамического качества (увеличению подъемной силы и уменьшению силы лобового сопротивления) на до- и сверхзвуковых скоростях полета, обеспечению управляемости на сверхмалых скоростях полета. К внешней форме планера предъявляются требования по снижению радиолокационной заметности. Все перечисленные требования являются противоречивыми, а создание самолета, отвечающего подобным требованиям, представляет собой определенный компромисс.”

To read the patent you can click this link, it’s either totally safe or I’ve already infected my computer.

To stealth or not to stealth?

Disclaimer: Here we start to enter swampy waters. I’m not an engineer and can only discuss this topic in layman’s terms. I’m happy to be yelled at by actual engineers or people from the aerospace industry.

su-57 assembly

The Su-57 features a substantially reduced radar cross section compared to a typical Russian 4th generation aircraft, but this is a somewhat abstract way to discuss the subject. When we think about having low observation qualities or a small radar cross section (RCS) we are thinking about detection and engagement ranges from a particular type of radar, at a select band, and aspect. An aircraft could have a small RCS in m² when looking at it head on, but become rather visible from the rear aspect, sides, or when looking at it from below via ground based radar. It could have a tiny RCS to a X-band fire control radar, but be clearly visible to a VHF radar employing a wavelength of 1 meter or longer. A more technical paper, for example this one, explains the subject reasonably well:

if a typical air-defence radar could detect a target with an RCS of 1 m² (small fighter) at 200 nautical miles (NM), it would detect a target of 5 m² RCS (large fighter) theoretically at 299 NM (however, the upper limit of most ground radars is set to 255 NM). A reduced RCS fighter of 0,1 m² RCS would be detected at 112 NM and a stealth fighter of 0,001 m² RCS would be detected at 36 NM. The same logic applies to any kind of radar. However, concerning fighter aircraft radars, as well as air-to-air missile seeker radars, the respective ranges are considerably shorter compared to the ones of a ground radar. In theory, the RCS of some simple objects, such as a perfect sphere, can be well defined. In practice, most targets are rather complex objects and their RCS usually fluctuates considerably, as they move with respect to a radar.

Some commentators see the Su-57s design as a the wrong approach, unable to replicate a F-22 or F-35. As a consequence the design choice is incorrectly attributed to Russian inability to design a stealth aircraft, or some innate deficiency in the aerospace sector, for the simple reason that it’s inconceivable Russians might understand all the same things about modern air combat, and pursue a different design philosophy. This is mirror imaging. The Su-57 is not the result of a failure to execute. There are significant gaps in industrial capacity between the U.S. and Russian aerospace sector, materials, precision molds, additive processing, electron beam welding, yielding tight tolerances etc., but this is not the primary input into the Su-57 design.

The U.S. has placed most of its 5th gen eggs into the basket of stealth optimized platforms meant for beyond visual range combat, air defense penetration, and offensive counter air (if I’m wrong please yell at me). A substantial amount of money has been invested in this philosophy. The Chinese have to a large extent copied these designs, because that’s what they do. Russians think differently about stealth and the role of tactical air power in general. It is there to be one element of an integrated air defense network, and to support the ground force at the tactical-operational level, not to conduct aerospace blitzkrieg. Despite having access to plenty of information on stealth, a technology that’s at least 40 years in exploitation at this point, they developed different requirements for the aircraft.

Russia’s aerospace sector knows how to make good airframes, though not with the same tolerances, close fits, or materials. The Su-57 airframe has aspects that were clear structural choices not to invest heavily in stealth optimization at the cost of other requirements, the T-50 patent filing showed a planned RCS of .1-1m² based on shaping, though it does not include composites, radar absorbing, and radar blocking materials. So the target performance is a bit of a question mark. The biggest sources of radar reflection appear to be conscious choices.

There are oft cited statements in 2010 by the chief engineer, Alexander Davidenko, that the RCS was .3-.4 square meters, which is far higher than the potential .001-.01 m2 on a F-22. Unfortunately this is not exactly what he said. Davidenko said in 2010 that the F-22 has a .3-.4 m² RCS and that they are working with similar requirements for radar visibility. The actual RCS is undoubtedly a state secret, and Davidenko may have the wrong RCS for the F-22. He is also most likely giving out an average RCS as opposed to the RCS from a particular aspect. The point being is that he never said what the T-50 RCS actually is, from what aspect, in what frequency, or whether it was an average assessment.

Some see these comments as being in reference to shaping only, not the net RCS reduction after radar absorbing materials are factored into the equation. Those statements are also quite dated at this point, not reflective of improvements to successive air frames, though it’s reasonable to assume that the average Su-57 RCS would be somewhere in the .1-.3 range – but much lower from the frontal aspect.

Comparing Su-57 RCS to F-22 RCS is not especially helpful for two reasons. First, neither number is actually known, and the internet is awash with derived RCS figures that are relatively baseless. Second, there is no such thing as a general RCS value. The RCS is a conversion from the measure in decibels (dBsm), which varies depending on radar frequency, power, aspect of the aircraft being seen by the radar, and other factors.

It is doubtful that the Russian defense industry could build something optimized to the level of F-22 or F-35 from all aspects, because of the dedicated industrial processes required. It would entail considerable developmental risk, investment, and little payoff given the requirements. Yet the Su-57 does appear to be a very low observable design, particularly from the front aspect. The unit cost would also prove prohibitive for Russia to procure it in meaningful numbers. An optimized stealth aircraft that could not be built, or prove financially ruinous, would have been a brilliant yet somewhat pointless design. The airframe has good potential, and successive prototypes show attention to further RCS and IR signature reduction, though shortcomings are going to remain.

Judging the design based on the first series T-50 prototypes, without further investments in optimization, or the actual Izdeliye 30 engine, is probably a bit premature. Borisov made clear they would be revising the design, and a detailed look at the prototypes shows changes. After the first five prototypes, there were visible changes in the next three, according to Piotr Butowski. Three of the latest airframes (T-50-7,8,9) have an internally reinforced fuselage, panels that close the fuselage have been replaced with composite materials, the rear boom housing an EW suite has been lengthened, there are changes to the underside of the tail section, wingspan has increase from 14 to 14.1 meters – and the fuselage lengthened from 19.7 to 20.1 meters according to Butowski. The prototype T-50-9 was the first to feature a full electronic suite, which will be installed on the serial production model, as opposed to earlier examples that demonstrated partial kit.

One forum had a good example of differences in this image:

airbleed doors

There is a 2.5 year gap between #5 and #6, with the latter series showing modifications. The prototypes currently produced are meant to test different components of the aircraft – they are not the same, and as such looking at an image of any specific model and taking it for an example of the serially produced variant could prove a mistake.

Design considerations

air inlet.jpg

The inlets – these are a clearly a compromise in favor of performance over stealth, as Bill Sweetman wrote, “They are serpentine but the curvature is insufficient to obscure the entire engine face (as on the F-22, F-35 and Eurofighter Typhoon), so they also feature a radial blocker similar in principal to that used on the Boeing F/A-18E/F Super Hornet. Unlike the F-22 inlets, however, they feature a variable throat section and spill doors on the inboard, outboard and lower surfaces of the ducts. The result is a complex multiple-shock pattern at supersonic speed, which the Russians consider essential for efficient operation at Mach 2. The inlets also feature clamshell-like mesh screens and diverter slots to keep foreign objects out of the engine, as used on the Su-27 family.” The radar blocker could be a strong solution if it bounces radar waves multiple times inside the inlet prior to any return, then the blocker may prove quite effective, though its unclear the impact on performance. Currently the inlet design forms one of the main reflective surfaces looking head on at the aircraft.

The engine – the original AL-41F-1 (Izdeliye 117) is underpowered for the airframe, it is an interim power plant derived from the engine currently on the Su-35 and used on the prototypes, while Izdeliye 30 is developed. The AL-41F is a modernized variant of the AL-31, supposedly with 15% more power. Some batches of Su-57s will have to be bought with this engine, and perhaps retrofitted later. Izdeliye 30 is not expected to be completed until 2025, but will offer supercruise, delivering supersonic speeds without having to use the afterburner. It is not only more powerful, with 3D thrust vectoring, but also supposedly more efficient (17-18% according to Butowski). Top speed is set as Mach 2, supercruise at Mach 1.3. Izdeliye 30 has begun testing on one of the prototypes as of December 5, 2017 where it was seen launching from M.M. Gromov flight test center. That engine’s appearance seems to have a reduced cross section from the rear aspect in mind, when compared to the standard AL-41F-1.

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Izdeliye 30 being tested on the left

different engines.png

The oft touted feature is 3D thrust vectoring, compared to 2D on the F-22, or no thrust vectoring on the F-35. This is useful at high altitude, for maneuverability within visual range, and certain scenarios, but is not an especially useful feature for beyond visual range combat. The Su-57 will be able to out fly most aircraft, if it can get near them and not be shot out of the sky at long range by a superior 5th generation platform – the latter scenario remains in question.

Radar – The aircraft features the N036 Byelka radar system with five AESA arrays, 3 X-band and 2 L-band. These have good potential to be used for electronic warfare, and IFF, along with the dedicated L402 ECM suite in the tail. The L402 Himalays ECM uses its own arrays and those of the N036. The N036 is a first generation AESA, and it will be the first AESA mounted on a Russian fighter. The wing leading edge extensions house two L-band matrices covering a combined 270 degrees. It’s doubtful that the L-band matrices have the power to search for a stealth aircraft in any meaningful way. They can determine range and bearing of a target, not height. Their resolution is insufficient to provide guidance to weapons. Turning them on will reveal the position of the aircraft using them well before they are likely to detect anything. L-band is typically reserved for large ground based radars because of the antenna size required to make effective use of this wavelength. Beyond IFF, and EW, it’s unclear what the L-band matrices are for – perhaps utility can be improved via networking between multiple aircraft. Could be part of a kitchen sink approach to countering stealth, reminiscent of the USSR sticking lots of non-acoustic detection sensors onto its submarines to compensate for capability gaps in acoustic detection.

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IRST and DIRCM – The front mounted IRST turret is 101KS Atoll, a useful passive IR sensor, though having the ball turret in the front compromises stealth looking head on. It rolls back to reveal a surface covered with radar absorbing material, but that sphere is a no-no for stealth optimization. The 101KS might make the difference in the aircraft’s ability to search and target stealth aircraft, particularly in an environment contested by heavy use of jamming. Again, here the wavelength matters, as individual IRST may offer passive detection at relatively closer ranges, whereas there is investment in the U.S. in long wave IR detection as a counter-stealth technology. Overall the IRST system makes more sense than L-band for stealth hunting, but they would need to do something about the turret shape. The system does much better searching when queued, which the aircraft could attain via datalink from air defense radars.

Targeting pod

Targeting pod 101KS-N.jpg

Other electronic features of note include the 101KS-O directional infrared countermeasure (DIRCM) turrets, IR sensors to help improve pilot awareness, and recent testing with the 101KS-N externally mounted targeting pod. These features don’t appear well integrated into the airframe, and in their current configuration further compromise stealth characteristics. They may form part of an integrated missile approach warning system. Targeting pods represent useful features for multirole functionality, but better geared towards the aircraft’s competitiveness on the export market.

T-50-9 with DIRCM mounted (system can be seen behind cockpit)

t-50-9.jpg

Airframe design – early prototypes suffered stress fractures in the airframe, which required internal reinforcement. This was one of the issues that led to delays in the PAK-FA program. The overall design appears cramped, with uneven surfaces along the underside, round shapes, exposed grills in the first series of T-50s, etc. Some of these deficiencies have been addressed between T-50-5 and T-50-6 (this seems to be where the 2.5 year gap may have gone). T-50-9 is the first exemplar of both RCS improvements and the full onboard electronic kit. Izdeliye 30 should help further reduce the rear aspect RCS together with the IR signature, plus latest prototypes show cowlings and other modifications to the engine housing.

Early T-50-4 variant

early variants.jpg

The aircraft features a refueling probe, and has a rugged undercarriage with large wheels for those lovely Russian runways. The internal weapons bay appears to carry 4-6 medium range missiles, or 4 standoff guided weapons, plus two R-73 short range missiles in side compartments (I’ve not seen these open to offer proof). Given the bay size, the aircraft should be able to deliver standoff tactical nuclear weapons, i.e. it’s a good candidate for the dual capable aviation role.

 

Conclusion

I would not discount the Su-57. It is not a 5th generation stealth aircraft design gone bad due to failure to execute. The program has legs, and it’s going to amount to something. Even though the U.S. is quite dominant as an aerospace power, it’s important to remember we exercise analytical humility in looking at why other countries may choose a different design, based on the context of how they see air defense and their requirements. The fighter will allow Russia to attain qualitative air superiority over a 4th generation air force, and work with its own integrated air defense to counter penetrating stealth aircraft. It is a reflection of the Russian philosophical approach to the tactical aviation component of its Aerospace Forces (VKS), intended to support the strategic air defense mission first, and engage in standoff strike as part of offensive aerospace operations.

The Su-57 also reflects Russian skepticism on the money and effort that should be invested into stealth optimization and reduced RCS, representing what one could call the ‘good enough’ solution to the overall air superiority problem. Maybe that’s a mistake, and they should have just cloned the F-22 to the best extent possible, but the F-22 and F-35 work in part because they belong to a large infrastructure of logistics, stacks of ISR, datalinks, support platforms, and all the pieces that make the U.S. succeed as an expeditionary aerospace power. Russia is primarily a land force, where the other services provide support at tactical-operational levels to a strategic land campaign in the theater of military operations. An F-22 clone seems somewhat overkill for that mission, and a F-35 clone makes no sense at all for an air force that has no need to operate within integrated enemy air defenses.

The fighter will also offer Russia’s aerospace sector experience in producing a 5th generation aircraft with the attendant materials/composite requirements. In this regard it reflects limitations of Russia’s military industrial complex, but even if they could replicate the same industrial processes, the unit price could prove prohibitive given all the other competing modernization priorities. Moscow can purchase several regiments of these aircraft at a fraction of the price of Western analogues, and with multirole features the fighter could prove attractive on the export market. Current program cost and production requirements are within the industry’s ability to deliver, assuming they can get the engine work completed 2020-2025. Sticking to timelines is not something industry does well. However, I would not be surprised if India came back to buy it after shifting all the risk and development cost to Russia. The airframe is likely to evolve over time into something less observable – the overall direction is better optimization for stealth.

Comments/criticisms welcome as always. Dealing with aircraft requires a tremendous amount of technical knowledge and is at best a layman’s area for me, so maybe the less I touch on it the better.

Update: had some good feedback on how to interpret patent, and a few other design items. Overall update is that patent numbers should be interpreted as providing average RCS based on shaping only, prior to RAM application, and other features (radar blockers/IRST coating) suggest that the front is VLO optimized. So I’ve gone back to edit a bit – overall conclusion remains the same, but I’m more convinced about the aircraft stealth characteristics than how I looked at the design initially, though I was much more positive on Su-57 than many of the posts out there to begin with. 

Here is a closing shot of Putin walking away as billions in RUB of Russian taxpayer money finds a new home.

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31 thoughts on “Russia’s Su-57 fighter program – it’s worth following

  1. Some comments:
    – A number of competetive stealth wise US stealth aircraft (ie F32) had radar blockers.
    – The patent describes shaping and does not account for radar absorbent coatings and structures.
    – The RCS figure commonly used for western stealth aircraft (-40dbm2 for F22A) came with dubious metadata.
    – The RCS figure cited by the Su57 desighner for F22A performance should not be used for judgement of Su57 RCS performance beyound the claim made by said desighner – that the performance is compatible due to the lack of metadata.
    – Su57 includes a number of weapons (Kh58UShK, Kh38 and KAB250 series and others) in it’s bays that imply the broad air superiority mission within the first day of war, inlcuding destruction of the enemy air (with izd 810 LRAAMs) and land based radar (with D7UShK), critical command posts and aircraft on airfields (with Kh38 and KAB250 series).

    While it does not use any SDB equivalent, the Kh38 series does have a cluster payload, including smart anti-tank submunitions.

    Liked by 2 people

    • Radar absorbing coatings, meshes, and shields are ways to further reduce the RCS, but the shape and construction is essential – here there is nothing that compensates for design choices that compromise the aircraft’s stealth. Su-57 is going to be far more visible than a F-22 or F-35, that’s reality, and no radar coating is going to solve for it.

      Su-57 doesn’t include any weapons. Weapon programs, successful or not, bought in numbers or not, are their own thing and there is no unique weapon being devised for just the Su-57.

      Like

      • What I am trying to say is that it -is- as stealthy as the F35A (as in the same class, specifics would differ on the aspects, wavelengths etc) and you are misusing both the patent and the statement by desighner.

        The patent discusses the signature reduction using shaping to achieve around -20db signature reduction when compared to T10 airframe. With conservative (-10db) further reduction using absorbent materials and structures this would move into the F35A region of overall signature (with standard caveats regarding aspect angles, wavelengths, etc).

        As to weapons – we know what the Su57 internal bays can take due to the data on the (unique) hardpoints being used – UVKU-50U and UVKU-50L. The selection of armament specific to Su57 bays (and a number of other factors, such as historical Soviet Su27S/MiG31 employment within say the counter air operation) implies tactics and roles different to the ones that you describe.

        Liked by 1 person

      • Let me explain my view again. We do not know X, which is how stealthy F-35 is. We do not know Y, which is how stealthy Su-57 is. Having Davidenko’s personal impression of F-22 RCS based on shaping is fascinating, but doesn’t get us anywhere really. We do not know the successful degree of optimization. Also he doesn’t say that this is his interpretation of F-22 average RCS just based on aircraft shape.

        One thing people on forums don’t always appreciate is the ability of governments to keep secrets and the fact that running various models and simulations online really does not quite get you there. Neither does building a model of F-35A in your garage and trying out different band radars on it. So we do not know it is in the same class. It may be in the same class from frontal aspect, as it is better optimized there, and it could be garbage from other angles. We also fixate on radar and rarely get into the IR signature conversation, which is also a factor.

        Where does the patent say what degree of reduction is successfully achieved? Please post where this -20 dbsm comes from.

        I think the difference is I tend to be on the conservative side as an analyst based on what we know and what we don’t, so I cannot sit on my couch and imagine another -10 dbsm added to -20 dbsm, and get Su-57 into the same class as F-35A. Do you know where the RAM has been placed? How much of it covers the airframe? Is it of the same performance as U.S.? What % effect does the radar blocker have? I do not.

        I’m using Davidenko’s statement correctly by not reading into it that which is not demonstrated to be there. Point taken on the shaping-only RCS figure from the patent. I’ve gone back to rethink that bit.

        Liked by 1 person

      • Everything that’s been said about the alleged stealth deficiencies of the su 57 doesn’t stand up. It has all been rather fictitious. First is the intake. We’ve all seen the famous pic
        showing some engine face exposed through the nacelle. Its strange how there is just one pic of this despite many pics of the jet online. Anyway this podded engine setup with no true
        S duct but rather offset intake openings , is the same as the YF-23. Even the production blueprint. The podded engine and true blend wing design allows the jet to have a lower
        profile and this lower RCS. Hence why both the su 57 and YF23 are so low profile.

        Not only that, but the X-32 also had engine face exposure. This did not disqualify
        those jets. It doesn’t disqualify the su 57.

        Then there is the back. Sure its true that it doesn’t have the tapered engine tips that the F-22 has. But neither does the F-35. The back of the su 57 will have serrated engine cowling with
        a serrated engine tip just like the F-35. The shrouding around the su 57 engines are round. But that is also the case with the F-35.

        The bulk of low abservabilty, what gives a jet the stealth designation is if the fuselage was computer generated from the ground up, for stealth. We can see by the shape of the
        57 that it is. Another requirement is plan form alignment and internal weapons. Again, su 57 has both. The su 57 actually has some better features in thsi regard than the
        J-20 or F-22. The su 57 has levcons that give it some of the performance of a Euro canard without there being worse for RCs because they are flush mounted within the contours
        of the wings. This also allows it to have smaller vertical stabilizers. The su 57 has way smaller stabilizers than the f-22. The su 57’s are also all made of composite material. Which is also better for RCS.

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  2. Excellent and level-headed presentation of the kind current commentary on Russian capabilities is desperately lacking. One thing strikes me as odd-and it is not directly related to the Su-57 programme.

    If stealth is not such a great issue for Russia, and you explain very well why that might be so, then since a prototype in the form of the Mig 1.44 existed already from the early 90s-and we should bear in mind it was designed almost in parallel with the ATF in the US which resulted in the F-22-why not go ahead with that? The Mig 1.44 had already made its first flight back in 2000, was the result of an extensive development and seems to perfectly fit the stealthy but not fully stealth, clearly superior to the 4th gen, multipurpose but mainly useful in a defensive-interceptor role the Su-57 seems to be designed for.

    In a very simplified timeframe estimate, had Russia continued development of the Mig 1.44 back in 2004-5, then by 2010 it would likely be able to mass produce it, assuming at a rate similar to the Su-27 variants at about 8-10 per year, resulting in say already a force of 100 planes.

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    • Stealth is an issue but it was one requirement among several competing requirements. Given the missions do not call for the degree of LO expected of U.S. aircraft, and the cost associated with attaining it might be prohibitive, plus the developmental risk as well – they decided not to go in this direction. Why not Mig 1.44 of earlier demonstrators? I don’t know honestly, but from what I call Mig bid, Sukhoi bid and Mig didn’t win – which is for the best. Mig hasn’t made anything good in my opinion since Mig-31.

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      • MiG did not bid with 1.44, they bid with 1.46 which was built as a stealth airplane (a broad comparison can be made to J-20).

        Sukhoi worked on signature reduction since their T4MS entry in 1970-1972 and were developing a deep, all round, deep penetrating stealth strike platform in late 1980s/early 1990s. While stealth was not a significant requirement in the MFI program Sukhoi worked on stealth under their own initiative.

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  3. Nice work in the attempt to provide a balanced insight into an Su-57 program.

    The greatest problem related to any stealth designs or RCS related discussion is to actually find a clear definition or even basic agreements on what frequency being used to measure the RCS of an aircraft.

    As noted, almost and practically all claims of RCS are made without the additional information regarding frequency or maybe even taking into factor of path propagation factor or maybe aspect angle (frontal vs side aspect). Those are usually lead to dispute and confusion. Thus the Sukhoi designer’s claim of “0.3 sqm” and USAF “metal marble” claim cannot be disputed based on source as they could be both true.

    The following is a graphic of RCS of a frontal aspect RCS of my 3D model of KFX Taken from different frequencies :

    https://assets.kompasiana.com/items/album/2018/03/24/c107vhftox-5ab54344dd0fa8430e024072.jpg?t=o&v=700

    Notice the wild differences of RCS in various frequencies. I can claim the KFX have RCS of 0.001 Sqm (-30 dB) While my detractors claim 0.1 Sqm (-10 dB) and both claims are true, just different in frequency where the measurement is taken.

    The bottom line is, unless the condition is specified. it is hard to make any judgement regarding the “design target” of Su-57.

    Liked by 1 person

    • Yes but the frequency that mattes is the one that fire control radars operate at, which is typically X-band in 3-4 cm wavelength. Other frequencies will give you acquisition and visibility, but no target track, so you may see a larger cross section but practically you can’t do anything to the aircraft. I’m simplifying of course, but the point is that it really matters what the RCS is in the frequencies required to achieve a weapons quality track on the aircraft – not in other frequencies.

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      • I am pointing out the problem which often lost in discussion namely at which frequency the measurement is made.

        All RCS claims regarding Su-57 or other stealth fighter in respect does not mention at which frequency they are taken. How one know of the RCS value is for fire control or for the other kind of radar ?

        In short, How do you know if Sukhoi claims actually applies to fire control radar ? Is there a source or is it a general consensus made by community ?

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  4. “The aircraft features a refueling probe, and has a rugged undercarriage with large wheels for those lovely Russian runways”

    Dont you think, that this indicates a requirement for take-off from unpaved runways? As far as i know most US-Aircraft lack that requirement. It would make sense, if it really is build to support the ground force at the tactical-operational level.

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  5. Fair article overall, but the radar cross section section is not quite accurate.

    Firstly the 0.1-1m^2 RCS range that is given in the patent is specifically stated to be the _average_ RCS range, which is totally different figure than a frontal sector RCS, that is typically given for aircrafts. The frontal sector is by far the lowest for all stealth fighters, including F-22 and F-35, the RCS varies radically depending on the angle and sector. Like for example this (https://basicsaboutaerodynamicsandavionics.files.wordpress.com/2016/03/f_35_metal_rcs.png?w=1200) simulation shows, F-35 by shape alone (without RAM) can reach -30dB (0.001) from frontal sector, but from sides the RCS is typically between 0-10dB (1-10m^2) and that is not simulating the top and bottom sectors of the aircraft, which are even higher. Indeed Davidenko’s statement makes sense when we take it that he is talking about average RCS.

    It can be almost logically proven, that PAK FA’s frontal RCS is (much) lower than 0.1.

    Two main arguments:

    1. Comparison to aircrafts, which are known to be on that 0.1 class (clean, without weapons etc.) like Rafale, Eurofighter and Super Hornet.

    2. The fact that according to the patent the IRST is RAM treated on the back to minimize its radar return, when maximum stealth is needed.

    1:
    Rafale, Eurofighter and Super Hornet lack _most_ of the observable RCS reduction measures on PAK FA. They lack faceting, planform alignment, slanting of the inlet lips, blending of the canopy to the fuselage and door shaping. All opening doors on PAK FA employ the same zigzag shaping as other stealth aircrafts. The 0.1 category aircrafts do not. For example Rafale’s air refueling probe is fixed on an extended exposed position, whereas PAK FA’s probe is hidden inside the fuselage behind zigzag doors. Rafale’s radar is totally vertical, whereas PAK FA’s radar is tilted by 15 degrees (similarly to other stealth aircrafts). Super Hornet’s horizontal stabilizers are on a different plane than the wings (typical for non-stealthy older generation), whereas PAK FA’s horizontal stabilizers are on the same plane as the wings (just like F-35’s and F-22’s).
    It is illogical to think, that PAK FA would attain no advantage for its far greater employment of measures to control radar reflectivity. And indeed it is for a reason that it has internal weapons carriage and the others don’t.

    2:
    A metal sphere with 6 inch diameter has an RCS of 0.018m^2. There would be no point at all to treat the IRST with RAM, if the aircrafts RCS was on 0.1-1 range frontally. But reality is such that a 0.018 reflection from the IRST would ruin PAK FA’s stealth so they had to do something about it. With RAM you can pretty confidently take 20dB out of that RCS, which would put it at 0.00018. Of course the IRST isn’t metallic, so probably the base reflectivity is even lower, which only strengthens the argument.

    BTW F-32 (as seen on X-32) was supposed to achieve the VLO standard set by the USAF by using a radar blocker. So it isn’t just Sukhoi, but also the biggest aerospace company in the world, Boeing, who feels that radar blocker is totally suitable solution for VLO.

    Also the first picture supposed to be izd.30 is not it, but some Salyut work. Possibly for China or just for testing, but it is certainly not izd.30. They look very different, for example Salyut product has twice as many feathers as izd.30.

    Like

    • Good comments –

      #1 I think the frontal RCS is probably much lower than .1m² but there is no good way necessarily to place it. The gist of the argument in this piece is that this is a LO aircraft much better optimized than 4th gen analogues that have some stealthy features.

      It seems I’m wrong on degree of stealth optimization, because after more research some of the solutions to the shape are reasonably effective. Guess the RCS reduction is quite better taking all things into account.

      #2 I’m not sure what to make of the IRST. People post numbers and I don’t know where they come from. The IRST is not 6 inches in diameter but clearly much larger, and it needs to be facing forward to be of any use, without the radar absorbing coating. You have good point that there is no value in coating it with RAM if the front aspect was not VLO optimized.

      The bigger question is on the inlet design. It’s probably not as a big a challenge as some people make it out to be, but from the front it looks like the main issue. Well Boeing feeling like its X-32 radar blocker was a solution may be why Boeing didn’t win the competition – I’m just being cheeky, the radar blocker is clearly an answer, but it might have performance consequences. So I need to do more research into the impact and maybe take that criticism off the board.

      I’ll look at the izd.30 photo, and get something that looks right – probably was up late and thought it looked the part. Honestly I can’t visually place difference between Saturn engines just by looking at them and I’m glad there’s someone out there that can.

      Like

      • I just noticed, that the patent you linked is not the “stealth patent” I assumed you referred to. There is a patent by Sukhoi, which more specifically deals with the radar visibility reduction measures. And there is a patent about the radar blocker also.
        Stealth patent: https://findpatent.ru/patent/250/2502643.html
        Blocker patent: https://findpatent.ru/patent/262/2623031.html

        Sukhoi also tested S-ducts themselves on Su-47/S-37 as mentioned in the Sukhoi magazine. Picture of the page here: https://i.imgur.com/Wa7GTFT.jpg

        You really think the IRST is much wider than 6 inches (15cm)? https://i.imgur.com/g4GpQCT.jpg
        I got the figures for different sized metal spheres from a serious looking pdf about radar scattering. I found them to be interesting so I wrote the different values down. I tried to find it now, but I have too many files about stealth to comp through them quickly. I try to find it at better time and post it then. But here is another link, which shows 5.4 inch diameter metal sphere (KRTS-138) to have 0.015 m^2 RCS at 4.3GHz frequency. It isn’t identical to the the ball and frequency of the other source, but the similarity of the results suggests, that these are valid numbers.
        http://www.keycom.co.jp/eproducts/res/res02/page.html

        Like

      • I looked at a few studies online and was basically examining what 12 inch sphere might look like at 8-12 GHz frequency. Maybe 12 inches is a bit too big, but I thought 6 inches looked quite small for the size of that thing relative to the aircraft.

        I’ve rethought the inlet/radar blocker issue after digging more into the subject and looking at how the blocker can effect multiple bounces with a partial S-bend – also looking into something else of interest on the aircraft.

        Like

  6. Very thorough analysis, especially the technical part. The area that seems highly relevant to me, however, is also how will this plane operationally fit in other countries defence structures. Take Turkey, e.g. Since they don’t have nearly as developed air defence perimeter as Russia, would Su-57E be able to fulfill the Turkish needs?

    There seems to be a certain degree of similarity in military doctrines of both countries, as both emphasise ground forces and defensive capabilities (perhaps Turkey even more so). But would potential Su-57E purchase require require acquiring also extra S-400 battalions and radar equipment?

    Like

    • It’s hard to say without knowing Turkish requirements. Su-57 has multi-role features, good weapons bay, and options to carry a targeting pod, etc. So it would be a good export market contender. It doesn’t necessarily have the sensor package of F-35, but then again why does Turkey need all the capability offered by the F-35? Who are they planning to fight anyway? Besides Greece that is 🙂

      I think Su-57 will do just fine for most countries looking for something beyond the latest block F-16.

      Like

  7. P.s. sorry for missing my ID on two previous comments, it is getting a bit late (0415 local).

    While the stealth point has been discussed by several users (including myself) I think there is a second important point which did not see as much discussion as the stealth point, That is – expected role, tactics for the Su57 aircraft.
    I think it would be interesting to discuss them as an extension of the MiG31 (and Su27S) legacy, where MiG31 would be used in what can be described by a western user as an offensive counter air role, as a part of joint MiG31/Su27S (and other aircraft forces) conducting offensive air or counter air operation, because those have been widely studied in published literature and would form the historic basis for the Su57 development.

    Like

    • I’m decidedly skeptical on offensive counter air role for this platform. There’s little expectation that it would be bought in large numbers, or that it is necessary in this role when compared to the current 4th gen fleet Russia has. Su-27 and Mig-31 did not have the same mission. You’re welcome to expand on that thought stream though. It would be interesting to discuss them as an extension of these aircraft legacy but in my view incorrect – these aircraft are not going anywhere, and its unclear that Su-57 will ever be procured in sufficient numbers to substitute.

      You would equally have to prove that weapons for this role are even being bought in any substantial numbers for any aircraft let alone the Su-57, beyond the ‘well it has the mounting points on it.’ Just think about the reality of the proposition:
      – offensive counter air can be handled with cruise missiles, SRBMs, and other much cheaper means
      – Russia invested in standoff weapons precisely for this reason, because it is much more cost effective to kill runways via strike systems than to kill airplanes in the sky,
      – there is already a 4th gen tactical bomber and strike aircraft component to Russian VKS with standoff weaponry – what does Su-57 add to this picture?
      – There are far too many air fields out of range of Su-57 and its weaponry, plus the requirements are going to be vast, its not the sort of thing you would give to VKS
      – long range weapons are pointless against a 5th gen airforce because your radar detection range is going to be tiny, so izd. 810 is going to be for something like AWACS
      – Su-57 lifespan against a numerically superior 5th gen airforce outside of its own integrated air defense is going to be really short – again just think about the numbers.
      – China’s 5th gen air force is also going to be numerically superior, so in the initial period of war Su-57 will be on a one-way mission, especially given how well optimized it looks
      – In the U.S. the air force is the primary air defense, not land based air defense, so suppression of enemy air defense is a pointless mission for a high value aircraft

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      • I do not seem to be able to comment under the -stealth- thread 😦 so I would mention only one thing here, there is a difference in the relative signature reduction (db) and relative to the 1m2 RCS signature reduction (dbsm). So when I mean -20 db compared to T10 I mean 0,1m2 as it is 100 times smaller than 10m2, not -20dbsm which would get us 0,01m2 as it is 100 times smaller than 1m2.
        And sorry for the long winded rant.

        Back to employment. I would now discuss the counter air operation as the most useful example. You can see it being defined here: http://encyclopedia.mil.ru/encyclopedia/dictionary/details.htm?id=9475@morfDictionary
        Within that operation (and I would simply by leaving the maritime dimention out) there would be joint operations by SAM forces, fighter and interceptor forces to engage enemy aircraft in the air, to destroy airborne supporting assets, by missile troops and high power artillery, by bomber and ground attack aviation to destroy the enemy aviation and supporting assets on the ground.

        As a part of this operation MiG31 aircraft (which are probably not exactly what you would think when hearing offensive counter air) would be employed in joined formations with Su27S aircraft as they:
        – improve capability of such formations against airborne, deep, high value targerts (AWACS, stand off ECM, etc).
        – improve capability of such formations by providing improved ISR via datalinking, including CEC (note, this is Soviet era).
        – provide improved situational awareness to the broader formation by downlinking ISR information to the airborne and ground based command post (in Soviet era, now this would also be used to provide CEC for SAMs).
        [IMG]http://i63.tinypic.com/293ew53.jpg[/IMG]
        Offensive tactical operations by a MiG31 against a HVT
        [IMG]http://i63.tinypic.com/104nlhk.png[/IMG]
        Joint air operations by various aircraft
        [IMG]http://i68.tinypic.com/5a12cm.png[/IMG]
        Examples of Soviet era networking.
        As another part of this operation bomber and ground attack aviaiton would also be delivering strikes against ground targets.

        Su57 can provide both the air-air component of this operation as a part of joint operations by:
        – providing improved forward ISR to joint forces as well as CEC
        – providing flanking groups for the joint forces via stealth and supercruise (mobility)
        – providing the LRAAM capability with kinematics to further exploit it
        and the air-ground component of this operation and a part of joint operations by:
        – providing SEAD capability with internally carried Kh58UShK to enable operations by other groups of aircraft within the same force
        – destroying key targets (ie command posts), aircraft on the ground, using internally carried Kh59M2 cruise missile, Kh38 AGM with cluster payload.

        More or less all of this is going to happen over hostile territory as it did with (non survivable at first glance) MiG31. However the depth of such operations would most likely allow Su57s (and MiG31s before them) to retain a degree of support from airborne and ground based radar, long range SAMs (think of 40N6 guided via CEC by a forward positioned Su57), missile troops and high power artillery.

        While the numbers are indeed not advantageous to Su57 force per say (or to RuASF in general, USAF&co have a lot of aircraft) expecting RuASF to rely on a passive defensive strategy instead of developing and deploying specialised aircraft (such as Su57) to provide force multipliers in the classical operations (ie counter air operation, strategic offensive operation, etc) is strange.

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      • Ivan, I don’t think any of that employment is going to happen over hostile territory. Counter high value targets such as AWACS is a boutique mission and not really offensive counter air. Everything else is not only not going to be done with the Su-57, but does not need to be done with Su-57 and could be done cheaper/better/easier with other platforms that have better payload, are cheaper, have a weapons systems officer – which really helps if you plan to do any of these missions. Yes, you may notice Su-57 is a single seat aircraft which throws a wet towel over some of these strike mission dreams.

        Defensive strategic operation yes, offensive strategic operation – highly unlikely. Offensive counter air, for about 5 minutes before all of the Su-57s are probably dead.

        Like

      • This branching is a big confusing, I am repplying to this post:
        Michael Kofman says:
        May 31, 2019 at 6:48 pm

        You may be mirrowing the concept of the offensive counter air (which I may have misused trying to explain the Russian approach to air war) into the Russian thinking. And it appears (however I may be mistaken) that because offensive counter air mission is not perceived as possible then the defensive operation and it’s air component must then be passive in nature, over friendly territory.

        The issue is that a “defensive air operation” includes many offensive elements into the enemy territory (against combat and supporting aircraft, airbases, supporting ground elements such as radars, command posts, etc), as I have tried to describe above.
        Without such elements even a strategic defensive operation becomes passive in nature, looses depth (depth can be created by striking into the enemy territory) and as such is not viewed as acceptable. If you have time for further reading I would suggest reading works by Babich.
        While attack on the AWACS in the hostile territory may indeed be an uncommon mission, it is one of a set of missions that I have described (which form a counter air operation), and that set, while does not require the entire RuASF to be made out of Su57s would strongly benefit from “boutique” force multiplier capabilities (stealth, supercruise) on the subset of RuASF inventory, after all ~72 plane plan for Su57s is much smaller than the known procurement for the T10 series (Su30M2, Su30SM, Su35S, Su34).
        And because there is a strong desire to be able to fight an active strategic defensive operation (and maybe a strategic offensive operation against non peers) those force multiplier capabilities are important.

        Those missions cannot be done better with other platforms becasue:
        – they require supercruise
        – they require stealth
        F22A has been compared in terms of capabilities to MiG31 in Russian thinking because both have superior situational awareness and cruise speed over their peers which allows them to be manuevered into tactically advantageous positions during air combat.
        In essense if you remove the premise that RuASF does not have some sort of VLO requirement driven by a desired mission, which in turn is based on the premise that western sources (mis)report that it lacks the VLO capability it would all make sense.

        F35A (with all of it’s failures) is both strike aircraft and a single seater. Su57 has a number of features (ie assisant AI) specifically advertised to enable the pilot to run many of those missions without the aid of a second crewman. Partially those features have already been developed and deployed for advanced 4th gen aircraft ie Su35S.
        Note that the bulk of the above described strike missions are against known targets (ie airfields) using smart, stand off munitions (ALCMs, ARMs, AGMs) and are conducted as a part of a combined force, including two seater aircraft (ie Su34s which are used as both bombers and ECM platforms).

        Like

      • Ivan, I don’t need you to explain the “Russian approach to air war.” I really feel at times here you did not read the blog post as you are literally repeating things I have written there as ‘your idea’ and are trying to explain these ideas as if they were not covered in the blog.

        It is a multirole fighter, but simply is not going to be used, and is not optimized, for enemy air penetration. Sorry – this aircraft would have a really short lifespan in that role. The theory of ‘it has the function by virtue of whatever can be stuck inside the internal weapons bay’ is not what one would call a solid understanding of concept of operations and doctrine.

        As for the rest, like I said before – you’re wrong. Su-57 will serve as a boutique capability to establish pockets of local air superiority and counter-stealth. All the other ideas are in the vein of ‘its a plane with hard points so technically it can do all the missions.’ Yes technically you can stick rocket pods on it and then post about how its really a ground attack aircraft.

        F-35 has maybe $60 mil more in tech onboard, and I’m still skeptical of it performing as a single-seat strike aircraft. You will note its performance is substantially affected by virtue of having that mission. F-35 is meant to replace an inventory of 4th gen aircraft in those roles – Su-57 is not meant to replace anything. Again the list of reasons for why you’re likely to be wrong is so long it would take a separate blog post to cover. So your theory is that Russia built an aircraft optimized for mach 1.8, high speed maneuverability, and high angles of attack, so as to do tactical bombing and standoff strike with long range PGMs, having no weapons officer onboard to manage those systems so the pilot can focus on flying – interesting.

        You know ALCM is like 5000km in range right? So in your theory, Russian invested in numerous of land based missiles for the destruction of critical objects, along with stand off cruise missiles, but Su-57 will be flying into enemy territory to fire Kh-58 and drop KAB bombs (with externally mounted targeting pod no less lol? 🙂 Anyway, we’re going to disagree because I think too much of your theory on airpower is somewhere in 1970s.

        Like

  8. I just noticed, that the patent you linked is not the “stealth patent” I assumed you referred to. There is a patent by Sukhoi, which more specifically deals with the radar visibility reduction measures. And there is a patent about the radar blocker also.
    Stealth patent: https://findpatent.ru/patent/250/2502643.html
    Blocker patent: https://findpatent.ru/patent/262/2623031.html

    Sukhoi also tested S-ducts themselves on Su-47/S-37 as mentioned in the Sukhoi magazine. Picture of the page here: https://i.imgur.com/Wa7GTFT.jpg

    You really think the IRST is much wider than 6 inches (15cm)? https://i.imgur.com/g4GpQCT.jpg
    I got the figures for different sized metal spheres from a serious looking pdf about radar scattering. I found them to be interesting so I wrote the different values down. I tried to find it now, but I have too many files about stealth to comp through them quickly. I try to find it at better time and post it then. But here is another link, which shows 5.4 inch diameter metal sphere (KRTS-138) to have 0.015 m^2 RCS at 4.3GHz frequency. It isn’t identical to the the ball and frequency of the other source, but the similarity of the results suggests, that these are valid numbers.
    http://www.keycom.co.jp/eproducts/res/res02/page.html

    Like

  9. To nitpick – Su57 (most likely) cannot carry 3 MRAAMs in it’s weapon bays as the CGI you have presented would imply.

    Like

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