Russian Su-57 Aircraft Thread (PAK-FA and IAF FGFA)


Tirdent

Junior Member
Registered Member
Bingo. The SU-57 is still considered work in progress by all accounts. For all we know, the Russians may still be working on the avionics and sensors for another ten years. There is no finished product to talk about unlike the F-22 which has been flying in active service for many years. Any attempts at comparison is frivolous at best.
Not so sure about that - there is a surprising amount of information on the systems architecture available if you know where to look (including a patent). In fact the article linked by TerraN_EmpirE provides a surprisingly frank and concise summary which indicates the philosophy may incorporate features to enable easier upgrades (like the Gripen NG segregated critical/non-critical architecture that has generated a lot of interest). This is one of the problems with the F-22 strongly centralized philosophy that has slowed the pace of its upgrades (while it is receiving some, the cost and effort is very high) because any software or hardware change automatically impacts critical functions.

Also the type and number of CPUs (late-model Elbrus-series RISC processors) have been published. While this chip is pretty obsolete by Western consumer electronics standards, but as gelgoog noted, so are the electronics used in the F-22 and F-35 due to stringent military certification requirements. I'm not an electronics expert, but the Elbrus seems particularly well-suited to real-time applications like this.

In any case 5th gen has moved away from technological stuff like OVT and super cruise - they are periphery. The 5th gen battlespace is about information and therefore about avionics, sensors, and information fusion. Situation awareness dominates every encounter, as was in history and so is in the future.

In fact speed literally kills. An aircraft leading-edge temperature increases with aircraft speed The detection range from IR sensors increase by a factor of 3 between sub sonic speed at 0.8 mach vs speed at 1.8 mach. Having supercruise sounds great but its utility has diminished in the age of IR sensors.
As I've described on this forum before, the USSR was an early adopter of intra-flight data-linking, having it in service at a larger scale on the MiG-31 and Su-27 than the US as recently as the late-1990s and early-2000s (when the low-cost MIDS terminal enabled near-universal retrofit of Link-16). The Russians are no strangers to the concept of networking and the Su-57 is known to adopt a new, bespoke system.

Also, Western aircraft (with the exception of Typhoon - PIRATE is a superlative capability!) are not very well equipped with IRSTs, unlike Russian fighters, so the problem is not symmetrical and supercruise continues to offer benefits for the Su-57. No IRST at all on the F-22, the F-35 EODAS is a MWIR system for better A/G performance rather than long range detection of aerodynamic airframe heating and Rafale's OSF-IT was by all accounts not a success (AFAIK later batches retain only the TV camera for target ID).
 

Brumby

Major
Not so sure about that - there is a surprising amount of information on the systems architecture available if you know where to look (including a patent). In fact the article linked by TerraN_EmpirE provides a surprisingly frank and concise summary which indicates the philosophy may incorporate features to enable easier upgrades (like the Gripen NG segregated critical/non-critical architecture that has generated a lot of interest). This is one of the problems with the F-22 strongly centralized philosophy that has slowed the pace of its upgrades (while it is receiving some, the cost and effort is very high) because any software or hardware change automatically impacts critical functions.

Also the type and number of CPUs (late-model Elbrus-series RISC processors) have been published. While this chip is pretty obsolete by Western consumer electronics standards, but as gelgoog noted, so are the electronics used in the F-22 and F-35 due to stringent military certification requirements. I'm not an electronics expert, but the Elbrus seems particularly well-suited to real-time applications like this.
The real hard work in avionics and sensor development are the deliverables in the form of capability output. Not in the architecture vision. As I said, showing some equipment that potentially are part of the preassembled package doesn't equate to a functional system ready to execute missions. The difference very often is 15 years or more of developmental timeline. in other words show me the tangible evidence that progress is being made and not claims of progress.

As I've described on this forum before, the USSR was an early adopter of intra-flight data-linking, having it in service at a larger scale on the MiG-31 and Su-27 than the US as recently as the late-1990s and early-2000s (when the low-cost MIDS terminal enabled near-universal retrofit of Link-16). The Russians are no strangers to the concept of networking and the Su-57 is known to adopt a new, bespoke system.

Also, Western aircraft (with the exception of Typhoon - PIRATE is a superlative capability!) are not very well equipped with IRSTs, unlike Russian fighters, so the problem is not symmetrical and supercruise continues to offer benefits for the Su-57. No IRST at all on the F-22, the F-35 EODAS is a MWIR system for better A/G performance rather than long range detection of aerodynamic airframe heating and Rafale's OSF-IT was by all accounts not a success (AFAIK later batches retain only the TV camera for target ID).
The Russian IRST systems were non-imaging type and several generations behind western standards even with OLS-35. What can you tell me about OLS-57? .
 

Tirdent

Junior Member
Registered Member
An improvement up the technology chain are non-imaging cooled IRST systems and are used in Su-27 variants including SU-35 (OLS-27 to OLS-35). These have much better sensitivity and thus longer range. Otherwise they share similar limitations as the older IR systems. Imaging, uncooled IRST systems are not used in fighter IRST systems but in missiles. They easily beat both uncooled and cooled non-imaging systems in almost every respect. They have decent range and as they are imaging, can also recognize and identify targets. They can do passive ranging and can detect/track large number of targets simultaneously. Imaging, cooled IRST systems are used in modern western IRSTs like Pirate, FSO and EOTS. These outperform all other types handily and have all the capabilities of imaging uncooled systems but offer much better sensitivity and thus better range and target discrimination abilities.
Uncooled IIR sensors have dramatically improved in performance recently, but for a long-range detection system like an IRST (as opposed to a missile seeker or MAWS sensor) cooled systems are still the way to go. Higher cost, complexity and weight, so uncooled sensors are popular for the applications I mentioned previously, but PIRATE is definitely cooled for good LWIR performance (it has an additional MWIR channel for imaging modes, IIRC).

Imaging sensors can be further divided to scanning and staring arrays. Scanning arrays have been used in earlier FLIR/IRST systems (Pirate, AN/AAAS-42, many FLIR systems) but staring arrays have really taken over during the last decade. EOTS and DAS use staring arrays as do many later targeting pods and for example DDM-NG in Rafale. Compared to scanning arrays, modern staring arrays have higher sensitivity, longer range and better reliability and higher frame rate with better image quality.
EOTS (I meant to say EOTS rather than EODAS in my earlier post too!) is a scanning system. Staring arrays are not very useful in a long range sensor but ideal for continuous wide angle surveillance (MAWS/EODAS). DDM-NG is likewise a scanning sensor though - this enables near-spherical coverage with only two sensors rather than 6 on installations like the F-22, F-35, J-20 and Su-35 (a cost and space constraint).

Need I say more?
Yes. When was that graphic created and which Su-35 does it refer to? Although the second question is pretty much rhetorical admittedly, because the current Su-35S (as opposed to the 1990s Su-27M with canards which never entered service) is known to use a fiber-optic avionics bus. Do you honestly believe that would be this low in bandwidth?
 

Tirdent

Junior Member
Registered Member
The real hard work in avionics and sensor development are the deliverables in the form of capability output. Not in the architecture vision. As I said, showing some equipment that potentially are part of the preassembled package doesn't equate to a functional system ready to execute missions. The difference very often is 15 years or more of developmental timeline. in other words show me the tangible evidence that progress is being made and not claims of progress.
Since I'd have to be an insider to have that information and would be under NDA not to publish it if I was, that's clearly impossible. We don't even have that confirmation for Western avionics architectures either, for the exact same reasons, so what's the point? We can chose to believe or disbelieve, but that's about it.

The Russian IRST systems were non-imaging type and several generations behind western standards even with OLS-35. What can you tell me about OLS-57? .
That's because they came decades before today's Western IRSTs. OLS-35 is pretty much an evolution of those systems with an A/G imaging channel added, so yes it's no match for PIRATE but this is not necessarily an indication of the capabilities of a clean-sheet design. No specifics have been released about the Su-57's 101KS-V.

It is not for me to believe or not but it is being quoted that the SU-35 is using a mil-std 1553b data bus. If you have sources that are reporting a different data bus adoption I am happy to be updated.
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Page 6: Волоконно-оптические и цифровые мультиплексные линии связи = Fiber optic digital multiplexed data buses
 

gelgoog

Senior Member
Registered Member
Whilst the F-35 sensor fusion is much publicised, it was build on the architecture of what went into the F-22 sensor fusion. It was an integrated systems architecture with sensor antenna embedded throughout the plane in order that the VLO features are not compromised. In other words, it is not an afterthought that you have with pods. Obviously when the F-22 was put together the state of the avionics at that time was not as advanced as when the F-35 came along.

View attachment 51316
The comment about the F-22 lacking IRST is repeated so often that it deserves to be addressed. The F-22 with the most powerful radar (AN/APG-77) at that time combined with the EW suite (AN/ALR-94) was a very potent sensor combination then and today. Those F-15 drivers will testify to that. Every time they go up against an F-22 they get popped without being able to locate their presence. Incorporating IRST at that time was simply an overkill against known and future threats. At that time non-imaging IR systems weren’t really that good and radar systems were very effective. As new imaging IRST technology has emerged it became increasingly popular on fighter aircraft in recent years. Both F-22 and F-35 have all aspect IR suppression and it would be interesting in terms of how effective IRST will be against these two birds.

...

As for the other technology gaps that you mentioned with the F-22, there are planned upgrades for the F-22 to ensure it remain the premier air to air superiority fighter. I have more confidence in the F-22 completing its upgrade before the SU-57 can complete its planned development.

Since you referred to SU-35, let's see where it is in the avionics bus architecture.

View attachment 51317

Need I say more?

….so the SU-35 is better than the F-22 in avionics. Please tell me more in what ways..
…. are you suggesting such features are lacking in the F-22/F-35? It is said that the strength of the F-35 is not in its stealth but in its sensor fusion. The autonomous feature of its sensor fusion engine is what makes it so powerfully different in terms of sensor directed operation and threat identification. Non of the sensor fusion features in Rafael and Typhoon come close in its autonomous capability. It is why the millions of line of codes are for.

Not according to the data bus technological tree above.
We are talking of a plane not a phone. In logic it is called a straw man argument.
The F-22 software was programmed in Ada and reused a lot of prior code. The F-35 software avionics were totally rewritten in C++. So no, it might use similar concepts in some ways, but it is all new. In fact this decision is probably the main reason for the delays with the F-35.

The F-22 does not have an IRST because back then the West was simply behind on that particular technology. In particular the USA. Originally the US considered such systems too expensive and unreliable. That perspective only changed when NATO had access to the MiG-29 in West German service. The only people who worked on similar systems in the West back then were the South Africans and the Israelis. Those countries had more combat exposure to Soviet fighters so they realized the problem with not having IRST and helmet mounted sights earlier. Similar reason why it originally did not have the AIM-9X.

With regards to the Su-35 I have enough data on it to know that it has nothing to do with prior Flanker series avionics. On seeing that diagram I question which Su-35 they are talking about. Also, like I said, the Eurofighter has less advanced avionics than the F-22. The databus is also worse like your diagram shows. So thank you for proving my point that the Eurofighter has really ancient avionics in it.

My talk about comparing chips does make a point. Ever heard of Moore's law? The Russians have better processors available to them than either the i960MX processors used in the F-22 or the PowerPC processors initially used in the F-35. AFAIK Russian military-industrial projects in aviation and space use some Elbrus derivative of the SPARC architecture. Probably the MCST-R1000. That is a quad-core 64-bit CPU with vector instructions fabbed at 90nm. Which is outdated but less so than the PowerPC processors used in the F-35. Let alone the i960MX.
 

Gloire_bb

Junior Member
Registered Member
The F-22 does not have an IRST because back then the West was simply behind on that particular technology.
That's wrong. US had better IRSTs on F-14 series.
But f-18 series dropped them(partially making up with a2g pods), and USAF never really felt the need(iirc, IRST was one of longer-surviving NAVAIR requirements from the NATF days).
TBH, i was surprised when they decided to adapt it to their 4th gen birds.
Change of the prospective may have actually affected Europeans, but not the US.
 

Tirdent

Junior Member
Registered Member
Yes, relative to other IRSTs at the time AN/AAS-42 was extremely impressive as well, so much so that most current US products (TigerEye, Legion, IRST21) still draw heavily on it. All in all it only ever equipped a small fraction of the total US fighter fleet due to high cost (same story with its modern day off-shoots) and as it was LWIR only and generally based on older technology its imaging capabilities are markedly inferior to PIRATE. That's why it was often teamed with the older TCS TV-system for target ID on the F-14.
 
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Brumby

Major
Since I'd have to be an insider to have that information and would be under NDA not to publish it if I was, that's clearly impossible. We don't even have that confirmation for Western avionics architectures either, for the exact same reasons, so what's the point? We can chose to believe or disbelieve, but that's about it.
Claims are merely claims unless it can be substantiated in some shape or form. Whether it is NDA is just red herring. If there is progress, we know of it because there are prototypes or product demonstrations that at least suggest progress is being made.

That's because they came decades before today's Western IRSTs. OLS-35 is pretty much an evolution of those systems with an A/G imaging channel added, so yes it's no match for PIRATE but this is not necessarily an indication of the capabilities of a clean-sheet design. No specifics have been released about the Su-57's 101KS-V.
…. except OLS-35 when measured against western standards of development. Since Pirate is the favourite standard bearer, how does OLS-57 stack up against it? Other than its official designation as "101KS-V" we know nothing about it even after so many years of development.
If we know nothing of it, how can claims be made of its capabilities?


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Page 6: Волоконно-оптические и цифровые мультиплексные линии связи = Fiber optic digital multiplexed data buses
I don't know Russian and so this is the translation of page 6.

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We still don't know what data bus architecture it is using from your source. However I know that MIL-STD 1773 is the fibre cable equivalent of MIL-STD 1553b.

upload_2019-3-10_13-2-33.png
 

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