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Thread: IRBIS and the detection of low RCS targets

  1. #1
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    IRBIS and the detection of low RCS targets

    The newest Russian PESA radar has been claimed to have a detection range of 165-240 KM against a target having between RCS 0.1-0.5 m^2.

    How realistic is this claim, and if true, what are the chances of an IRBIS equipped su 27/30x against F-22.

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    It may be possible withy an extremely powerfull emiter. IRBIS seems to follow that path. I am not sure on the data but, by increasing four-fold the raw power radiated (as IRBIS is claimed to do) surelly you can "see" smaller RCS objects.

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    Quote Originally Posted by fft View Post
    The newest Russian PESA radar has been claimed to have a detection range of 165-240 KM against a target having between RCS 0.1-0.5 m^2.

    How realistic is this claim, and if true, what are the chances of an IRBIS equipped su 27/30x against F-22.
    All that data say nothing about high-up. Closing or leaving. There is not constant RCS at all.
    Detection does not mean tracking or even guiding. Test data and practical data are much different. When you do know in advance, where to look and what the return is to exspect from that, you can fine-tune the filters related to that. There is still a time gap, between a first return spotted and a stable confirmation, that you have a true signal from a fighter and not from something other in the air. Your radar will not distinguish between a signal from an airliner further away, but in the "line of sight" of your radar at first.
    There is not question, that IRBIS will spot a F-22 nearby a.s.o.
    If enough reaction-time is left to make use of that is questionable so far.
    But there is a constant race in capabilities and the number of fighters with that is very limited.

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    NIIP IRBIS-E RADAR
    400 Km for 3m2
    powrfullest radar in word
    IRBIS radar range show in this brochure
    Attached Images Attached Images  

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    There are two quite huge articles (in russian) on the NIIP official site and they contain a lot of information about Irbis.
    The average power is about 6KW, the peak - not less than 20KW. The antenna can be steered +- 60deg laterally and 120deg around its axis which combined with electronical scanning gives about +- 120deg scanning zone in azimuth. The radar utilises new russian made signal processors. In very sensitive mode Irbis can detect 3sqm target from 350-400km - but the "trifle" here is that such mode has relatively slow scanning, for example NIIP gives it in sector of 100sq deg (i would say that the scanning of 120deg forward sector /and 10deg thin/ would require about a minute).
    NIIP also says that "extremely low observable targets with RCS of 0,01 sqm" like cruise missiles can be detected from up to 90km.
    < Because it is also written that Irbis can detect A2A missiles, there are some disputes on russian forums wether the AMRAAMs could be found and even .. shot down :diablo: >

    The very curious matter is that NIIP says that the RCS of F-22 is approximately between 0,1 and 0,5 sqm and hence the distances of detection 160-240km.

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    real RCS of F-22 is 0.1
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    What is particularly interesting (or funny) is that the range against a 3 sqm fighter is about the same as for a huge ship:diablo: And if the scanning process takes that long it is unlikely to be usefull at all.

    PAK-FA
    real RCS of F-22 is 0.1
    Yes of course you must know it

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    Quote Originally Posted by Scorpion82 View Post
    What is particularly interesting (or funny) is that the range against a 3 sqm fighter is about the same as for a huge ship:diablo:
    Scorpion, range against naval targets is significantly affected because of sea clutter. look up different radars including the captor, and it will be the same.


    And if the scanning process takes that long it is unlikely to be usefull at all.
    this is also a very doubtful statement. i know hexpop has mentioned it, but i would like to see the support for the same!
    his statement makes little sense since the 100 sq degrees niip has mentioned is the usual angular coverage by pure esa scanning, not the mechanical turn, and the irbis-e has two all new solo data and signal processors for this purpose.
    remember, while the irbis-e makes use of the osa/wasp antenna array which is sligthly worse than the bars in terms of receive sensitivity, it makes up for it by a much more powerful dual twt.

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    I really don't know how much time the scan takes in these 100sq deg (100% sure these 100 sqdeg mentioned), but it may be about 4-5 seconds, which is normal for a particular scan frame. Well - 100 sq deg is scan frame 10x10 deg or 20x5 deg, the usual pure ESA scanning zone is 60x60 deg or in theory 3600 sqdeg.
    In the article is also mentioned that Irbis can detect incoming A2A missiles not less than 6 seconds before their possible impact and this time should be enough to set countermeasures and escape.
    Last edited by hexpop; 5th January 2008 at 15:57.

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    Quote Originally Posted by Nick_76 View Post
    Scorpion, range against naval targets is significantly affected because of sea clutter. look up different radars including the captor, and it will be the same.
    I know, nonetheless I mean to remember that already similar ranges were given for older radars and the ratio of detection range was significantly different between AA and Sea targets. The Russians throw around the 400 km figure since the early 90's at first for the N-011 for the old Su-35. It is no news that the N-011 didn't held what it promised and I have some doubts that Irbis will do so.

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    Quote Originally Posted by hexpop View Post
    I really don't know how much time the scan takes in these 100sq deg (100% sure these 100 sqdeg mentioned), but it may be about 4-5 seconds, which is normal for a particular scan frame. Well - 100 sq deg is scan frame 10x10 deg or 20x5 deg, the usual pure ESA scanning zone is 60x60 deg or in theory 3600 sqdeg.
    .
    first, lets find out the pure esa scan limits- these shud be equal to or slightly greater or lesser than the bars. thats approx 40 degrees in elevation and 40 in azimuth, within that scan area, the beam will move in milliseconds with the processor controlled beam scheduler. the signal processor will do its job, and data processor will show it to the pilot.

    now as you say, the mechanical scanning comes, then the scan rate will be a combination of mechanical and electronic, but how niip has done this is their ipr. they could still achieve a higher rate than what the slow rotation of heavy antenna suggests, since that phased array can shift beam in milliseconds without entire antenna turning.

    so the basis is that irbis or bars will usually detect their targets very fast within pure electronic field of regard, and it will take more time when mechanical scanning is employed.

    in real life, with awacs everywhere nowadays, that mechanical scanning is useful for one thing, allowing the pilot to fix his antenna to side while taking a bvr shot and trying to crank his airframe away. and of course, useful for tactical build up, when you are doing a volume search early on, and allocating targets, if there is no awacs.

    In the article is also mentioned that Irbis can detect incoming A2A missiles not less than 6 seconds before their possible impact and this time should be enough to set countermeasures and escape
    yes but you have to take into account the speed of the aam as well and the extremely low rcs of the aam as well, in a head on profile.

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    Quote Originally Posted by Scorpion82 View Post
    I know, nonetheless I mean to remember that already similar ranges were given for older radars and the ratio of detection range was significantly different between AA and Sea targets. The Russians throw around the 400 km figure since the early 90's at first for the N-011 for the old Su-35. It is no news that the N-011 didn't held what it promised and I have some doubts that Irbis will do so.
    thats understandable, but it may be simpler, that the trials havent really touched on a2s work yet, and hence only estimates and earlier figures for bars etc are being trotted out.

    also, the irbis vs n011 comparison is not linear since we know, n011 is a planar array which was superceded by n011m which was a pesa, and now irbis is a pesa which makes use of the bars capability.

    the bars may do 300-400 km against large targets at max height of the mki platform. a bars radar detected a su-27 in trials, at 330 km.

    and sukhoi has been pointing out that the su-35 would get a new radar for some time, so its possible that they were just proceeding per plan.
    also, the n011m is said to be a modular radar, with twt upgrades possible (provided power gen is also addressed).

    ur quite right that final figures for irbis may not be as impressive or fancy, theres always that risk.

    imo, the 400 km range for irbis is likely to be vs and tws, will be lesser than that
    Last edited by Nick_76; 5th January 2008 at 17:11.

  13. #13
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    Quote Originally Posted by fft View Post
    The newest Russian PESA radar has been claimed to have a detection range of 165-240 KM against a target having between RCS 0.1-0.5 m^2.

    How realistic is this claim, and if true, what are the chances of an IRBIS equipped su 27/30x against F-22.
    Well the regular Su-27's radar can detect a 3 m^2 target fron 100 miles away, so this 0.1-0.5 m^2 is believable.

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    From a typical altitude of 10km sea level targets beyond around 400km will be below the radar horizon. No matter how big their RCS is, an Irbis at that altitude will not be able to see ships that are further away and neither will any other fighter radar.

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    Quote Originally Posted by Trident View Post
    From a typical altitude of 10km sea level targets beyond around 400km will be below the radar horizon. No matter how big their RCS is, an Irbis at that altitude will not be able to see ships that are further away and neither will any other fighter radar.
    So we can assume that the Flanker/Irbis test did choose a higher altitude to spot it.

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    Quote Originally Posted by Nick_76 View Post
    Since that phased array can shift beam in milliseconds without entire antenna turning.
    Since that phased array can shift beam in milliseconds without entire antenna turning.
    Can it that really? No!
    What is with the signal propagation delay?
    The spot moved than halted (Transmitting -->Duration-->Receiving-->Processing) than moved than halted(Transmitting -->Duration-->Receiving-->Processing)...
    A full scan need some 1/10s for EScan, depending on the distance and puls retention frequency!
    Last edited by KKM57P; 5th January 2008 at 20:17.

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    Quote Originally Posted by 1MAN View Post
    Well the regular Su-27's radar can detect a 3 m^2 target fron 100 miles away, so this 0.1-0.5 m^2 is believable.
    you might want to check your sources on N-001. I wouldn't trust any of these Russian brochure figures.
    Visit my Chinese military blog at http://china-pla.blogspot.com/

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    The shifting of the beam of Bars/Irbis is said to be around 0.4 milliseconds.

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    Quote Originally Posted by 1MAN View Post
    Well the regular Su-27's radar can detect a 3 m^2 target fron 100 miles away, so this 0.1-0.5 m^2 is believable.
    except that it's probably more like <0.0001 m^2.

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    Quote Originally Posted by sferrin View Post
    except that it's probably more like <0.0001 m^2.
    Always when I see this figure I have the same thought, do Americans really know how to use metric units correctly? Someone tell me please which from these pictures the F-22 RCS will be equal to a cmxcm pixel for a radar.
    Last edited by martinez; 22nd May 2010 at 11:01.
    <Find a job you like doing, and you'll never have to work a day in your life>

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    Quote Originally Posted by martinez View Post
    Always when I see this figure I have the same thought, do Americans really know how to use metric units correctly?
    Last time I checked 1 cm^2 was 0.0001m^2. Or do they use a different metric system where you live?

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    then perhaps in the future we could see a russian testbed be it a flanker or some modified transport or whatever mounted with this radar and get as close to alaskan airspace as possible!would be interesting to see the results!

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    Quote Originally Posted by martinez View Post
    Always when I see this figure I have the same thought, do Americans really know how to use metric units correctly? Someone tell me please which from these pictures the F-22 RCS will be equal to a cmxcm pixel for a radar.
    The problem with RCS figures is that they're overwhelmingly subjective. When you see an RCS figure, it is typically going to be the smallest figure for the object. That is typically only going to be achieved from one angle, and in the case of the F-22A it is probably from a head-on aspect, which is what it needs being designed as a fighter anyway. Put a radar directly above an F-22, F-117, or B-2, and I'd bet you'll get a significantly higher figure due to the much greater surface area and the more favorable aspect angle for the antenna. The F-22 is equipped with what it needs to take the most advantage of the low head-on RCS of course, all of the radar and ESM gear will tell the pilot where the targets are so he can act accordingly and put himself in the best position to get a first shot opportunity.

    So yes, the F-22 could have an RCS as low as 0.0001m2, but it's not going to be an overall, every aspect angle figure.
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    Quote Originally Posted by pilatus View Post
    then perhaps in the future we could see a russian testbed be it a flanker or some modified transport or whatever mounted with this radar and get as close to alaskan airspace as possible!would be interesting to see the results!
    Except that the Raptors flying out on intercept sorties have been carrying external fuel tanks...I suspect that part of the reason for that is to deny accurate RCS measurement of the airframe! The jet also probably has some sort of system similar to that used by the F-117A where they can increase the RCS as well. That is primarily done for safety reasons, so that ATC radars can see the jets and deconflict civillian traffic if needbe.
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    Good point, but even with the tanks it would still have a low enough RCS so it might not take aslong to pick up, but it might satisfy some of the radar manufacturers claims perhaps!?

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    Quote Originally Posted by SOC View Post
    The jet also probably has some sort of system similar to that used by the F-117A where they can increase the RCS as well. That is primarily done for safety reasons, so that ATC radars can see the jets and deconflict civillian traffic if needbe.

    That'd be this guy right here. (Essentially the same function as the little pyramids you'd see on the F-117).
    Last edited by sferrin; 17th January 2009 at 20:30.

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    Quote Originally Posted by sferrin View Post
    Last time I checked 1 cm^2 was 0.0001m^2. Or do they use a different metric system where you live?
    Now I am not sure what you mean. Martinez has written cmxcm, that means 1 cm^2 which is exactly what you have provided. Where is the difference, then?
    Last edited by flex297; 6th January 2008 at 01:57.

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    Quote Originally Posted by tphuang View Post
    you might want to check your sources on N-001. I wouldn't trust any of these Russian brochure figures.
    That's my fault I ment 100km NOT miles.

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    Quote Originally Posted by SOC View Post
    The problem with RCS figures is that they're overwhelmingly subjective. When you see an RCS figure, it is typically going to be the smallest figure for the object. That is typically only going to be achieved from one angle, and in the case of the F-22A it is probably from a head-on aspect, which is what it needs being designed as a fighter anyway. Put a radar directly above an F-22, F-117, or B-2, and I'd bet you'll get a significantly higher figure due to the much greater surface area and the more favorable aspect angle for the antenna. The F-22 is equipped with what it needs to take the most advantage of the low head-on RCS of course, all of the radar and ESM gear will tell the pilot where the targets are so he can act accordingly and put himself in the best position to get a first shot opportunity.

    So yes, the F-22 could have an RCS as low as 0.0001m2, but it's not going to be an overall, every aspect angle figure.
    Given the fact what pilot glass in F-22 is fairly open, i'm very sceptical about that figure. For example, a single metallic button/wire/tooth/medalion/whatever on pilot dress will already provide much large RCS than that. There are also some other problems, and anyone with basic understanding in physic can see why F-22 RCS cant be less than 0.01m2 even in ideal condions (frontal area, x-band, etc).

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    Quote Originally Posted by Chrom View Post
    Given the fact what pilot glass in F-22 is fairly open, i'm very sceptical about that figure. For example, a single metallic button/wire/tooth/medalion/whatever on pilot dress will already provide much large RCS than that. There are also some other problems, and anyone with basic understanding in physic can see why F-22 RCS cant be less than 0.01m2 even in ideal condions (frontal area, x-band, etc).
    First off, I wasn't necessarily agreeing or implying that the 0.0001m2 figure is accurate.

    Secondly, the canopy glass has been treated and is not exactly radar-transparent, alleviating the effects of the internal reflectors.
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