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Thread: Su-57 News and Discussion -version_we_lost_count!-

  1. #91
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    You would have to be above looking down on the F-35 for that to ever be an issue.

    Next.
    "The early bird gets the worm but the second mouse gets the cheese."

  2. #92
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    Quote Originally Posted by panzerfeist1
    By stating what is stated there?
    No, by making various leaps of faith


    Quote Originally Posted by panzerfeist1
    2014 sources states where the GaN MMICs will be used since they are already created
    In 2014 they states their development program finished and produced several kind of UHF GaN modules. Then those modules can be used to reduce dimensions and weight of some ESM system.

    Quote Originally Posted by panzerfeist1
    later in 2015 they have GaN AESA present on their EW systems.
    where did they even mentioned the EW system is Himalayas like you are trying to imply?


    Quote Originally Posted by panzerfeist1
    So why do they have GaN MMICs present on their EW equipment(according to niip) while the only hinted EW to utilize GaN was on that Rostec PDF as a brand new feature. hmmm brand new feature using GaN, 2015 they say GaN is present on their EW systems. What does that tell you? Do you actually believe that they are not suggesting their 4 GaN MMIC types is present, but that they have other GaN MMICs that are present on their aircraft but not the ones mentioned on Rostec? pg17 of niip catalog "Usually, solid-state gallium-arsenide and
    gallium-nitride amplifiers are used as active
    elements of active phased-array antennas of
    present-day EW equipment."
    You haven't seen yes this makes alot of sense at this rate. But the source states GaN present on AESA systems. Unless your going to argue that the GaN mmics that are present just dont happen to be on rostec which has only gave mentions of which equipment will have it.
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    In short, in a paragraph about cutting edge technologies for EW material and developement, they said usually GaAs and GaN are used in present day EW equipment.What they said is totally correct because in the market at the moment there are many EW system using GaAs modules, and some uses GaN modules. They didn't say Their EW system uses GaN. Honestly, even if they did, there is no reason for us to believe that Himalayas is the EW system with GaN modules. For example: Northrop Grumman can correctly say " GaN T/R modules are used in radar system we produced " but that doesn't mean we should assume APG-77v1 and AGP-81 use GaN (at the moment we only know that TPS-80 has GaN element). Or BAE can correctly say "we produced EW system with GaN modules" but that doesn't mean we should assume AN/ASQ-239 use GaN, at the moment we only know EPAWSS uses GaN. My point is you making too many assumption and faith jump from vague information


    Quote Originally Posted by panzerfeist1
    The developement project is already completed, says will be used.....UHF modules not created you say......
    You should read slower before you reply, i said those UHF elements weren't created specifically for Himalayas, like you can put a Sniper-XR pod on B-1 but Sniper-XR isn't created for B-1 only

    Quote Originally Posted by panzerfeist1
    TheWell atleast the smartskin explanation you were helpful however ironically the Spectra I heard has happened to have GaN from another forum I visited.
    Spectra will have GaN in future batch, but it doesn't use GaN at the moment. Nevertheless, GaN is not a requirement for the so-called smart skin.


    Quote Originally Posted by panzerfeist1
    Same materials being used, same efficiency and size reduction claims.Why I also hinted the fga-35 (3d) is that its weight reduction as a radar from a previous AESA radar got drastically reduced by 1.5-2 times similar to the weight of the EW systems that got reduced by 1.5-2 times smaller being based with the same LTCC MMICs.
    Size reduction and efficiency in form of percentage how do you know know they are the same without a base number?? What if the previous version is bucky?. Imagine someone said his house dog is half as big as her father, his house cat is half as big as her mother, then someone else concluded that the dog and cat are equal in size. Won't you think that will be a ridiculous assumption?


    Quote Originally Posted by panzerfeist1
    Like stating how good its by jamming AWACs at 700km and LEO satellites at 300km? Your probably meant the context of saying whats the jamming power and what state the jammed equipment will be in. But I was just stating a previous mentioned GaN EW system and other systems that have surpassed it in range
    You have yet to give us the citation to these range
    Eitherway these numbers are meaningless if you don't know the radar cross section of assets that you want to protect and their distance to radar. If they are very far from the radar then it should be easy because the return is weaker

    beside jamming satellite is easy because they don't have high power


    Quote Originally Posted by panzerfeist1
    ...At this rate do I have to hold your hand whenever I post something and even give page numbers prior like I already did?

    An important line of activity for KRET is the development of
    ultrabroadband antenna systems using the AESA active phased array
    radar. In the AESA, every element or group of elements has its own
    miniature microwave transmitter, working in the frequency band
    from 1 to 18 GHz.
    Powerful solid-state amplifiers, made of gallium-arsenide and
    gallium-nitride technologies, are used as AESA’s active elements in modern EW solution. Thanks to them, the equipment’s weight can be
    reduced by 1.5–2 times, raising reliability and efficiency by 2–3 times
    No you don't have to hold my hand, but in any debate you are expected to back up your view with citations/links. Extraodinary claim need extraodinary evidence and all that. Anyway, individual microwave transmitter can transmit between 1 to 18 GHz doesn't mean the bandwidth of radar will be from 1-18 Ghz, this especially true for multi funcional array. Have a look at this pattern by Northrop Grumman Corp in 1987.
    The transmit-receive cells are fully functional at broadband and narrow band radio frequencies. In the narrow band of 9.2 to 10.2 GHz, the active antenna system would operate as a radar system. In the broadband range of 2.0 GHz to 20.0 GHz the active antenna system is fully functional in electronic countermeasures and radio frequency jamming
    https://patents.google.com/patent/US4823136

  3. #93
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    Same Gutenev statements but on a different version, this time from Military Watch:

    Regarding the cost of the Su-57, prominent Russian lawmaker Vladimir Gutenev, a member of State Duma's expert panel on the aviation industry, stated "The fifth generation fighter jets are undoubtedly competing with U.S. F-22s and F-35s, but it is considerably cheaper even though it has similar characteristics, while in some aspects, for example, manoeuvrability, it does better than the U.S. jets.” The lawmaker further stated regarding the fighters’ service in Syria: “The time our four Su-57 aircraft spent in Syria definitely allowed us to get additional information on this aircraft's ability to detect [using communications systems] U.S. F-22 and F-35 aircraft which are operating in the same airspace.” This was in reference to the United States’ deployment of Raptors and Israel’s deployment of its F-35I jets over Syrian airspace. Monitoring stealth fighters' transponders has long been a key means for U.S. adversaries to track its most advanced combat aircraft - an issue recently highlighted by the U.S. military.
    http://militarywatchmagazine.com/article/70770

  4. #94
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    @Spudman

    You would have to be above looking down on the F-35 for that to ever be an issue.

    Next.
    Spud. You don't seem to think that Lockheed built stealth compromising features into the design of the F-35. Do you think Sukhoi would build stealth compromising features into the su 57 ?
    Last edited by KGB; 11th July 2018 at 15:42.

  5. #95
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    Every fighter is a compromise in one way or another. What you have to determine is will the compromise affect the fighter in any significant way.

    My point is that LM's experience with VLO gives them more knowledge on what they can do (and not do) with regards to how a feature will affect the RCS of the aircraft, especially in an operational & wartime environment. I am not saying that Sukhoi will not "eventually" gain the same level of knowledge, just that they do not have it now.
    "The early bird gets the worm but the second mouse gets the cheese."

  6. #96
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    I am not saying that Sukhoi will not "eventually" gain the same level of knowledge, just that they do not have it now.
    That's a pretty bold statement, although I don't think you realize it. When we built HaveBlue and even the follow on F-117 we didn't have 3d printers, computers had very little processing power for simulations, computer aided design tools were in their infancy and not very reliable, and we were very limited in what we can do with composites. They don't have any of those problems today. Heck, they even got the radar absorbent materials we used on the F-117, and they have had almost 20 years to improve on them. So, although Sukhoi may not have the same level of knowledge (and experience) as LM now has, it is certainly sufficient.

  7. #97
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    Quote Originally Posted by ActionJackson
    Why wouldn't you? I believe you misunderstand how fire control radars work. They don't operate *simultaneously* throughout a 8-12 GHz range. Rather they have that bandwidth and *can* operate within that band on demand. Basically, they operate within a 10-20MHz band that hops around randomly throughout their bandwidth. It's this hopping ability that allows for low probability of intercept.

    A photonics radar would work the exact same. It is not simultaneously scanning the entire 1-100GHz band. It is operating in a 10-20MHz band that can randomly hop throughout that band. You do want this! It takes low probability of intercept to the next level and you can run an algorithm to periodically scan near the high 100GHz region of its bandwidth to find stealth aircraft while spending most time in in the 8-12 GHz region where there is less atmospheric absorption.

    But I do agree that the technology is a long way off.
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    10th July 2018, 12:06 #70 ActionJackson ActionJackson is offline
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    Quote Originally Posted by XB-70
    When you've obtained multiple bearings to a signal source from known locations over a short period of time then you have located the origin of the source - in real time to a small region of uncertainty.
    Who knows the means of locating the F-22's or whether it was real time or after analysis of mission data, it's largely irrelavent. For all we know they could have rolled a UHF radar up to the test area to track the F-22's movements and reactions.... simple fact is, in multiple translations on translation tools, we get this....

    "We were probably able to clarify a number of possible and accompanying data on the ability of the F-22 and F-35 to detect our aircraft in the short-term stay of our Su-57s in Syria in February this year - telemetry provided a significant reason for their improvement," - said V.Gutenev.

    to detect our aircraft - Unambiguous, nothing lost in translation
    telemetry provided a significant reason for their improvement - Same, also specific

    Then we get the full treatment in this thread of the typical deny, deny, discredit the source, deny, try to interpret it in 200 completely unrelated ways, deny, discredit...etc by the local bots. Enough to convince me it's right on the money and worthy of tipping to defence media to see if they want to run it.

    I've been saying it for a long time, "stealth" is not "just stealth". There's varying degrees of observability between LO to true VLO. The question of which aircraft would more often prevail in an encounter comes down to exploitation of the radar max range equation. If aircraft A has a lower RCS from operationally relevant angles (noticed some of the uneducated in the last thread were talking about the RCS of the very bottom of the aircraft... clueless) and a better radar than aircraft B then more often than not it's going to get the first shot in an encounter, immediately putting the opponent on the defensive where their SA and low RCS quickly disappear.

    At a certain point in stealth design, it comes down to tiny details to get to actual VLO. Turning of screws to a particular angle to prevent the most minute amount of specular return, removal of a canopy frame causing surface discontinuity diffraction, stealth shaping of the inside of the cockpit (as well as a small jammer built "inside" the cockpit at a concentration point), extreme sharpening of all leading edges, closing of airgaps, removal of cavities between the airframe and intakes, mm perfect laser directed application of ram strips to the skin to consistently achieve the highest level of effectiveness.

    Meanwhile....



    1 - surface discontinuity, corner reflector - causes both specular and diffraction return to source radar ... forget the ram, a recent video on Su-57 canopy treatment only stated a 60% reduction in RCS from the metalized treatment
    2 - surface discontinuity at a normal to the aircraft's axis causes diffraction return to the source radar
    3 - surface discontinuity at a normal to the aircraft's axis causes diffraction return to the source radar
    4 - HUD (inside) - specular return through canopy



    1 - cavity - causes resonance
    2 - cavity - causes resonance
    3 - cyclindrical pitots - massive specular return
    4 - large levcon cavity - causes resonance


    1 - cavity, surface discontinuity - causes diffraction and resonance - not blended with airframe
    2 - no sawtoothing and pinching of control surface edge, cavity - causes resonance
    3 - fat, rounded leading edges - causes high specular return compared to extremely sharp (1mm diameter) leading edges
    4 - cavity - causes resonance



    1 - Multiple sources of specular and surface discontinuity return - resonance depending on wavelength
    2 - massive surface discontinuity almost at normal to axis - the gaps in these areas are quite large, inches in size


    Almost forgot... radar disco ball/infrared headlamp
    Brilliant post.

  8. #98
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    Quote Originally Posted by XB-70
    That's a pretty bold statement, although I don't think you realize it. When we built HaveBlue and even the follow on F-117 we didn't have 3d printers, computers had very little processing power for simulations, computer aided design tools were in their infancy and not very reliable, and we were very limited in what we can do with composites. They don't have any of those problems today. Heck, they even got the radar absorbent materials we used on the F-117, and they have had almost 20 years to improve on them. So, although Sukhoi may not have the same level of knowledge (and experience) as LM now has, it is certainly sufficient.)
    Yeah, especially sufficient to avoid internet-enthusiast level of blunders against LO. The level of arrogance this discussion implies on the part of some people is simply amazing. One thing is not having all the experience in the manufacturing or maintenance aspects of LO, which is very logical and everybody would expect, and other completely different is not being capable of getting even extremely basic aspects of the design and shaping right... especially when you are the one formulating the theoretical basis that allowed LM to design stealth in the first place. This is simply ludicrous...

  9. #99
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    That's a pretty bold statement
    Looking at the Su-57 makes it self-evident and valid.
    "The early bird gets the worm but the second mouse gets the cheese."

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    @Spud

    Every fighter is a compromise in one way or another. What you have to determine is will the compromise affect the fighter in any significant way.

    My point is that LM's experience with VLO gives them more knowledge on what they can do (and not do) with regards to how a feature will affect the RCS of the aircraft, especially in an operational & wartime environment. I am not saying that Sukhoi will not "eventually" gain the same level of knowledge, just that they do not have it now.
    You just cant give it up can you..

    @Rall
    Brilliant post.
    Brilliant alight. You are just the kind of guy that he is targeting to give credence to his blatant trolling.



    ^ That's some surface continuity right there.

    A round speedbump between the canopy and nose. And that's just the beginning of the stuff that would be brought up as problems with the design if there was Sukhoi on the serial plate.
    Last edited by KGB; 11th July 2018 at 18:05.

  11. #101
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    @SpudmanWP

    Looking at the Su-57 makes it self-evident and valid.
    The delusions you internet fanboy stronkists have.. Is just astounding.

    No US or NATO official has operated on anything other than the assumption that they are dealing with stealth competitors in Russia and China. Or did you think they refrained from starting F-22 production again because the su 57's engine cowling was unpainted ? Lol.

    But hey. I wont stop you from enjoying your fantasy world. I wish you'd just keep that fantasy world in F-16.net or something like that.
    Last edited by KGB; 11th July 2018 at 18:24.

  12. #102
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    This is where LM's experience comes into play. With "continuous curvature" calculations and proper RAM/RAS, this kind of surface feature does not have to adversely affect a fighter's VLO profile. What LM did is exponentially better than what Sukhoi did with the Su-57.



    btw, I found a portrait for your basement bedroom wall.

    Last edited by SpudmanWP; 11th July 2018 at 18:25.
    "The early bird gets the worm but the second mouse gets the cheese."

  13. #103
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    subscribed, this seems like a very interesting thread
    Last edited by terryna; 11th July 2018 at 18:26.

  14. #104
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    Im not arguing about the F-35 vs su 57. I am just pointing to what YOU and your ilk would SAY if there was SUKHOI on the serial plate of the F-35 and not LOCKHEED.

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    Once again, I have not said that the SU-57 in not to some degree stealthy, just that due to lack of experience (shown in the oblivious use of IRST balls, vent slits, corner reflectors, etc) that it is not to the level of the F-22/35. Give them a decade or two of experience combined with an increase in tech availability and I have no doubt that Sukhoi should be able to get into the VLO range of RCS.
    "The early bird gets the worm but the second mouse gets the cheese."

  16. #106
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    This is just getting painful (perfect reason I don’t find it worth my time to post on this forum anymore).

    KGB, give it a rest. The pathetic attempts to bring the F-35 into the discussion are sophomoric at best and frankly, idiotic if I were to be honest. Your paranoid attempts to deflect attention from the Su-57 with these lines drawn on the F-35 make you even more of a laughingstock and punchline than you were before.

    L-M has 37 years experience building LO aircraft (ones that are actually in service). The manufacturing tolerances and finish on the F-35 speak to that experience. If you want to engage in a tit for tat exchange on that, I think you will find the harsh reality of high resolution photos deeply depressing.

    We will see soon enough the build quality of serial Su-57’s within a year or two. I’ve always been under the impression that the aircraft is a work in progress, Russia tends to take incremental steps introducing new weapon systems.
    The internet minions claiming the Pre-serial Su-57’s are VLO as is, are fooling themselves. Even when people pointed out the unfinished nature of the project, people such as yourself would scream “troll”, then just as predicted, Sukhoi would make modifications and improvements.

    I’ve said it a million times on here, LO shaping of an aircraft has been made much easier with advances in computing and modeling. Building that airframe and incorporating apertures, antennas, control surfaces, maintenance access, and gap tolerances isn’t. There is a learning curve. I fully expect the Su-57 to evolve considerably over the next 5-7 years.

    There is no “western media conspiracy” against the Su-57. Unfinished military projects are always targets of defense “experts” and journalists. It doesn’t help that Russian media sources and officials make contradicting and exaggerated claims of progress, capability, and dates. I recall that article from the George Washington University thinktank, the Russian expat professor stated his probable date for large scale production of the Su-57 no earlier than 2025. People lost their minds on this forum and claimed he was a fool, full rate production was right around the corner. Then full details of the GPV came out, then officials started stating the Su-57 wouldn’t see FRP until after the second stage engine was complete post-2023. Seems he knew a bit more than our resident forum moron brigade.

  17. #107
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    Give them a decade or two of experience combined with an increase in tech availability and I have no doubt that Sukhoi should be able to get into the VLO range of RCS.
    @SpudmanWP - VLO isn't like a meter or a kilogram (or a decibel per square meter). There is no scientific consensus on what the term means. The Russians have said their spec is a metallic sphere the size of a "tennis ball". So if you define VLO as -30dBsm then it isn't going to be VLO. If you define it as -20dBsm then it is. And if you define it as -25dBsm then it will be if they just barely exceed their spec. But in all cases it is simply your interpretation of the term and others may legitimately argue otherwise.

    That said, I'm pretty sure you will say that the F-35 is VLO. And the Russians are going to exceed its spec in under a decade with Okhotnik.

  18. #108
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    There you go yet again. You couldn't be that arrogant. So it has to be blatant trolling. You are trolling this thread if you have the gall to write that Internet enthusiasts like yourself have a superior grasp of stealth than Russia and the Sukhoi design bureau. Ironically the country who makes the best AIR defense systems in the world. Systems that NATO members would risk losing the F-35 to acquire.

    Anyone who wasn't so arrogant would question their own Internet pseudo knowledge of RCS (IRST & all) before they made such claims that you do about the su 57.

  19. #109
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    FBW says that there is no witchhunt against su 57 and these are the same guys who can't seem to find a single thing wrong with the J-20.

    Which is strange because the J-20 is an odd looking aircraft. Built by China who has no experience.
    Last edited by KGB; 11th July 2018 at 20:04.

  20. #110
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    Quote Originally Posted by SpudmanWP View Post
    Once again, I have not said that the SU-57 in not to some degree stealthy, just that due to lack of experience (shown in the oblivious use of IRST balls, vent slits, corner reflectors, etc) that it is not to the level of the F-22/35. Give them a decade or two of experience combined with an increase in tech availability and I have no doubt that Sukhoi should be able to get into the VLO range of RCS.
    No need.
    To your pain and agony.. Sukhoi is right where they make lots of waves in the US world sandbox. The US leading hegonomy is not what it was 10 years ago.
    A truoblesome thought i know, but its better to get over it.

    USAF Col Forlof own words back in
    2008, RF;
    - "Their jets is a tad better".

    That was the 4th generation jets, in which granted, they had some difference in service debute.

    Deja Vu for the 5th generation jets anyone?

    Edit; And while the Su-57 prototype made a snap visit to Syria for a few days, there is that GIF where it launch a missile appears to be the Kh-59MK2, a standoff missile from internal W-bays.

    Something the usual suspects have now been all over. It cannot use W-bays, bla bla bla.
    Another amusing thought, the two Su-57 prototypes where spottet by a youtube poster on a final approach around Khem AirBase in Syria.
    But did or did not US know it flew down to Syria in the first place?

    The VKS must have almost daily flight past Iran-Iraq route from Southern Russia - Syria.
    But do they fly with military transponder on, and more importantly did the Su-57 fly with its transponders on.

    https://www.youtube.com/watch?v=AGjR4tZ32oM
    Last edited by haavarla; 11th July 2018 at 21:54.

  21. #111
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    Belief is a poor substitute for facts;
    US has produced 4 production manned LO aircraft, several unmanned (several other tech demonstrators, likely “black” experimental manned LO aircraft, likely several operational LO “black project” unmanned aircraft.

    The US has three generations of AESA flying, each building off previous, each with 3rd generation TRM (again built off operational experience).

    The US is still the world leader in bleeding edge aerospace R&D (though China is rapidly gaining).

    The gap is narrowing, just not with Russia. Not that any of the above would prevent the Su-57 from being a capable fighter when complete. Time will be a factor however, if it takes almost 10 years for the Su-57 to arrive in large numbers in active squadrons, that would be 25 years since the Sukhoi design bureau was selected to develop the Pak-Fa.

    Not exactly inspiring performance that would suggest Russian aerospace leapfrogging the US anytime soon.

    When you show up 15 years late to the 5th gen party, you better be bringing better champagne than the others.
    Last edited by FBW; 11th July 2018 at 20:47.

  22. #112
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    ^ 4th gen jets are still the backbone of the US airforce. France just started on a 5th gen project while Russia's is going into production.

    It is funny watching the Americans pump China's tires. I guess with their Russian engines, they are still the underdog.

    Love it or hate it, you can't ignore it. There is nothing quite like the su 57. Maybe deep down they know it's better. Which is why it gets all the attention.
    Last edited by KGB; 11th July 2018 at 21:15.

  23. #113
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    The mods decide to ban Berkut, but it's perfectly fine for KGB to continue with his drivel! I think it's hilarious that KGB feels so insecure that he start posting his garbage in other threads in his tit-for-tat behavior that seems like a 12 year old's.

    FBW said it perfectly. Su-57 is still work in progress and we still haven't seen the production aircraft. Su-57 might not pay as much attention to stealth as F-35 but it's not designed for the same missions and purposes as the F-35, and got other advantages like longer range and bigger weapons bays. Now can people stop with this back and forth crap? That goes for ActionJackson and RALL too.
    Last edited by RadDisconnect; 11th July 2018 at 22:27.

  24. #114
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    Some sage analysis from the western defense media on the su 57. And this is the kind of analysis that has convinced a large number of people that the su 57 isn't stealth.




  25. #115
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    I have never seen an official document which states the design rationale for SU-57 low observables.

    I can speculate that the SU-57 design provides an X-band detection advantage over western Gen 4 fighters. SU-57 edge alignment and RAM treatments likely provide effective X-band RCS reduction. This gives SU-57 first shot/A-pol advantage against Gen 4 fighters which would guard high value targets such as AWACS. NATO relies on AWACS directed Gen 4 fighters for air defense. Without the Air Battle Management coordination of fighters and long range L-band sensor capabilities of AWACS, NATO is vulnerable to air attack.

    NATO has no effective SAM defenses, so SU-57 does not need RCS treatments to protect against S-band SAMs. SU-57 does not appear to possess S-band RAS features which some western fighters possess.

    This speculative design philosophy is radically different that F-22 and F-35, where RCS was intended to counter the vast proliferation of Russian SAMs which would otherwise inhibit operation inside the IADS.

  26. #116
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    @djcross

    Typical thinly veiled innuendo about how.. you know..the su 57 will have an advantage over 4th gen fighters. And umm.. Russia doesn't need stealth b/c Nato's sam defenses. We get it. You came here to say that the su 57 isn't stealth. You just cant let it go.

    In 1986, the Soviet government initiated a "Multirole Tactical Fighter (MFI in its Russian acronym)" program to counter Western efforts to develop next-generation fighters, such as the US "Advanced Tactical Fighter (ATF)", which would become the Lockheed Martin F-22 Raptor.

  27. #117
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    @KGB

    MFI didn't have stealth requirement because ATF RFI 1982 didn't had it either. Only when Northrop proposed their stealth fighter and back it up with computer simulations USAF decide to put stealth as requirement and it was No1 requirement.
    Last edited by Krivakapa; 12th July 2018 at 09:39.

  28. #118
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    Once again, I have not said that the SU-57 in not to some degree stealthy, just that due to lack of experience (shown in the oblivious use of IRST balls, vent slits, corner reflectors, etc) that it is not to the level of the F-22/35. Give them a decade or two of experience combined with an increase in tech availability and I have no doubt that Sukhoi should be able to get into the VLO range of RCS.
    That experience hardly valid argument. LM has advantage of using computers much earlier due to US investment in semiconductors while Soviet Union was building steel mills in Ukraine. there was never effective investments in computing. it was horizontal spread out of medium tech assemblies.
    now skilled labor and investment is going at right places. and you can see it so fast development in various sectors of Russian economic system and Tanks like Armata platform.

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    The Su-57's Frontal RCS
    Cockpit and Aircraft Nose

    Click image for larger version. 

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    Travelling wave echo occurs when waves of the incident radar beam meet a surface at a shallow angle and run along the surface until they meet an object, different material, surface discontinuity or surface edge. They then bounce from the object/material/edge at an angle dependant on the incident angle. If they bounce from an object perpendicular to the direction of propagation of the waves, then the waves are bounced directly back along the path they came (towards the source radar).

    In the case of an Su-57 flying towards and adversary's radar there are a number of areas on the top of the aircraft which will cause travelling waves to bounce directly back to source. This occurs because the features that travelling waves reflect from are all at a normal to the aircraft's longitudinal axis.

    The diagram below shows how the OLS, canopy leading edge, canopy frame and the rear of the canopy will cause a large proportion of travelling surface waves to reflect back in the direction of the source radar. Green arrows represent the original direction of the travelling surface waves from the source radar and red are the echoed return. While the amount of energy returned from echoing waves is rather small compared to return from specular reflection (such as from the metallic pitot tubes seen above), undisputable science fact dictates that the features shown in the Su-57 top view below could be handled better to further reduce the aircraft's overall frontal RCS.

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    A sample of how other manufacturers handle surface waves travelling down the aircraft's length can be seen in the image below. Multiple layers of faceting leading up to the canopy glass surface, the lack of a frame to echo the waves and finally a faceted trailing edge cause the surface waves to reflect off at an angle that is consistent with the aircraft's plan-form design. The angles of the F-35's facets are designed to direct all reflected return (Specular and travelling waves) to a limited number of angles.

    The sensors on top of the aircraft are built into a gradually curving surface, but generally that will not be an issue as surface waves tend to stick to gradually and continuously curving surfaces (tip: the sky is blue because EM energy at the wavelength of blue light curves around drops of vapour in the atmosphere).

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    The image below shows the faceting on the F-35's canopy leading edge nice and clearly.

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    Other aircraft also adopt this principle.

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    This one too. I love this picture of the F-22 which is long overdue for a re-coat. The state of the surface really allows you to see the faceting and angle consistency in the magnetic RAM surface and fuselage features that are usually painted over.

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    Even the Iranians sort of have it.... but oh my gosh, what a beauty

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    In summary in regards to travelling wave return:

    There can be no dispute, based on real physical laws, that angled surface edges are preferred to surfaces at a normal to the aircraft axis for the purposes of reducing surface wave return in the context of frontal aspect stealth. Materials will go a long way to reducing radar return from poorly angled surfaces, but materials plus faceting will always be far superior.

    According to the Su-57's canopy's manufacturers, the surface coatings of the Canopy and presumably the 101KS-V (judging by it's colour) are coated with a combination Idium-Tin Oxide and Gold (and some other substances to make it a particularly thin film). It is a conductive but slightly absorbent film that reduces the radar return of the canopy material itself by 40-60%.

    The OLS's transparent surface helps hide the highly radar reflective, metalic components and lens of the IRST within (observable while it's being operated... ie. all the time). If the surface happened to be completely radar transparent then the OLS's internal components, having an RCS many dozens of times larger than the entire frontal aspect of most stealth aircraft would be exposed.

    101KS-V
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    On a side note, the aircraft also has two other spherical pods under the nose and on it's spine for it's IR countermeasures. These do certainly seem to be a major RCS issue as can be seen by their internal components. It seems these cannot be coated with lossy material as they would potentially melt when in use.

    101KS-O
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    .....to be continued
    Last edited by ActionJackson; 12th July 2018 at 13:52.

  30. #120
    Join Date
    Oct 2010
    Posts
    224
    ....cont

    Although the aircraft's canopy is covered in a very slightly attenuating, but conductive film, some radar waves do still penetrate the canopy and can reflect off objects inside. This image shows a number of cockpit features which will cause signal return back through the canopy. The HUD and the components in front of it, rear view mirrors, the helmet material...all contributors to RCS. Another side note: Also note the OLS. From the aspect this photo was taken, the feature presents an undeniably massive challenge for side aspect RCS.

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    One of the features of the F-35's and future US aircraft is the lack of a HUD and clean cockpit layout.

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    The pilot's helmet is made of carbon fibre (known for radar absorbing properties) and the canopy frame, even though concealed internally is faceted away from the source radar and is further concealed from the front behind a very thick piece of foam-rubber-like RAM. All other metallic frame components in the photo are concealed from site of incoming radar.

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    In summary: Low, frontal observability requires meticulous attention to detail, but also must be affordable by operators who choose to adopt aircraft with it as a feature. The F-35 program is such a large, multinational program with an equally as large amount of support infrastructure. While building the aircraft with a lot of additional care may cost a bit extra in procurement, it's the support costs of high end stealth over time which would be absolutely untenable without modernised maintenance systems that reduce man hours maintaining the aircraft's stealth features. The massive F-35 program has invested billions in tooling and robotic systems that are used in depots throughout the world.

    For relatively low GDP countries such as Russia that are going it alone with their own, much smaller stealth fighter programs, compromises must be made to reduce the amount of required stealth maintenance infrastructure while at the same time maximising aircraft availability rates. This is why Russia built the aircraft to their economic and tactical needs. The Su-57 is an affordable stealth fighter which is suited to defensive air to air operations over long distances unaided against the current European gen 4+ fighters.

    Against emerging and current 5th gen class fighters, it will be almost totally depend on Russia's large IADS and jamming systems to try to approach parity in combat. It'll not be produced in large enough numbers to justify the massive investment Russia needs to make in maintenance infrastructure to bring it up to the next level - full frontal VLO or ~-40dBsm or better frontal RCS
    Last edited by ActionJackson; 12th July 2018 at 14:16.

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