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Thread: Clean Rafale & Gripen RCS is 5 m2 and 3 m2. Not .05 & .03

  1. #61
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    who did that model? Do they have access to exact sizes, materials used etc.?

  2. #62
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    @KGB and basically everyone.

    Well Clearly we need to define at WHICH frequency those values are from. It's little of use to argue that X-planes have 0.01 sqm RCS without specifying at which frequency they are measured.

    Rafale and Gripen may have small RCS BUT.. at which frequency (band) that is more important.

  3. #63
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    When have you seen and manufacturer or service state a specific RCS value, or one for a specific radar band. They just release vague equivalents: golfball, insect, bird (L-M’s famous assertion about the F-22 in 2009, -40dBm2 “from certain angles”).
    KGB happens to be collecting his RCS values from comments sections on websites, a scientific approach if there ever was one.

    Most of the “figures” floating around are assumed values for x-band as that the most common airborne fire control radar band.

    Overall, this is a throwaway thread (though several posts on last page leaned dangerously close to making this a coherent and worthwhile topic).
    Last edited by FBW; 6th November 2017 at 21:01.

  4. #64
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    Am I interpreting that F-16 pole right?

    Is it indeed saying that there is a significant peak in returns around 0deg (directly head on)?

  5. #65
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    So? That's kind of expected with a straight air intake and no radar blocker.

  6. #66
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    Blue apple

    Yeah totally. Straight through

  7. #67
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    Blue apple

    Yeah totally. Straight through
    Siiiighhhhhhhh

    That doesnt look like a "F-16"...
    Read again what Blue apple wrote and to whom he was answering.

    And please, stop once and for all with references to wikipedia, ok?

    Cheers

  8. #68
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    Blue apple

    Yeah totally. Straight through
    I. Stop being so insecure every time someone mentions straight and intake in the same sentence.
    II. On the ground, PAK-FA body pointing down because the front landing gear is shorter.
    Last edited by moon_light; 7th November 2017 at 16:03.

  9. #69
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    Hoping to be included in the "several posts on last page leaned dangerously close to making this a coherent and worthwhile topic" on#63 post, allow me some point: I've cited meteor because its the heavier weapon that can be carried by EF semi-conformal pylon , same applies to Amraam or another that can fit: what reduces RCS is the virtual elimination of the pylon not about the missile dimension in itself.
    Picture posted by GarryA in #49 gives you the idea.
    Worring however to the perpendicular duct of such a missile fall IMHO on the "stealth, stealth and stealth" syndrome running amok around some posters from the other side of Atlantic.
    What increase the RCS of a jet duct are the propulsor blades moving, something you just have NOT on a Ramjet.
    Add that to see the interior of the Meteor's duct ,one should have to be at the very same quote and straight in the front of it as an even minimal angle would get it covered.
    To see a missile under the body of a Typhoon of even a Flanker you have to be at a much lower quote, not just a pair thousand feet and directly in the front i.e. a place no one would like to be.
    I repeat, the use of RCS have to be tactically convenient to make sense, it a mean to an end not a question of national pride or worse a male reproductive organ measuring contest.
    Last edited by Marcellogo; 8th November 2017 at 00:51.

  10. #70
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    Quote Originally Posted by Marcellogo
    I've cited meteor because its the heavier weapon that can be carried by EF semi-conformal pylon , same applies to Amraam or another that can fit: what reduces RCS is the virtual elimination of the pylon not about the missile dimension in itself.
    I was talking about RCS of missiles, a Meteor in comformal position likely still increase RCS more than AIM-9X at wing tips
    For the specific case of Typhoon, semi comformal Meteor doesn't need pylons but its inlet is perpendicular to Typhoon's fuselage, that isn't desirable
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    In Rafale or Flanker case, the pylon is still there
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    Quote Originally Posted by Marcellogo
    Worring however to the perpendicular duct of such a missile fall IMHO
    What increase the RCS of a jet duct are the propulsor blades moving, something you just have NOT on a Ramjet.
    Add that to see the interior of the Meteor's duct ,one should have to be at the very same quote and straight in the front of it as an even minimal angle would get it covere
    Cavity reflection is not only due to turbine blades. Inlets of stealth aircraft are coated with RAM

    Quote Originally Posted by Marcellogo
    To see a missile under the body of a Typhoon of even a Flanker you have to be at a much lower altitude, not just a pair thousand feet and directly in the front
    You can see them fine at the same altitude
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    Last edited by garryA; 8th November 2017 at 07:17.

  11. #71
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    Hoping to be included in the "several posts on last page leaned dangerously close to making this a coherent and worthwhile topic" on#63 post, allow me some point: I've cited meteor because its the heavier weapon that can be carried by EF semi-conformal pylon , same applies to Amraam or another that can fit: what reduces RCS is the virtual elimination of the pylon not about the missile dimension in itself.
    Picture posted by GarryA in #49 gives you the idea.
    Worring however to the perpendicular duct of such a missile fall IMHO on the "stealth, stealth and stealth" syndrome running amok around some posters from the other side of Atlantic.
    What increase the RCS of a jet duct are the propulsor blades moving, something you just have NOT on a Ramjet.
    Add that to see the interior of the Meteor's duct ,one should have to be at the very same quote and straight in the front of it as an even minimal angle would get it covered.
    To see a missile under the body of a Typhoon of even a Flanker you have to be at a much lower quote, not just a pair thousand feet and directly in the front i.e. a place no one would like to be.
    I repeat, the use of RCS have to be tactically convenient to make sense, it a mean to an end not a question of national pride or worse a male reproductive organ measuring contest.
    IMHO you are. Common sense vs "eyeball markI forum level integrated joint RCS measurement apparatus"

  12. #72
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    You need to account for creeping wave. Objects which are not within line of sight still have significant RCS.

  13. #73
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    You need to account for creeping wave. Objects which are not within line of sight still have significant RCS.
    Yes, exactly. I pointed that out of previous page when discussion turned to conformal weapons and tunnel mountings.

    Forum discussions on RCS seem to degenerate into a discussion based on people believe and what they see (and neither tells the whole story). Seems eyeball RCS is a lot like a religious debate, short on tangibles long on feelings and suppositions.

  14. #74
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    Common sense vs "eyeball markI forum level integrated joint RCS measurement apparatus"
    If only RCS is as simple as common sense...

  15. #75
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    KGB rants on about wikipedia [something any of us can alter FYI] yet claims figures estimated by the company and the Swedish Defence Materiel Administration are bogus. Yeah, that pretty much sums up his whole discussion.


    To answer StealthFlanker; Saab are quite proud over the fact that the Gripen has a L/O in a wide spectrum. Here's an article from DefesaNet:

    Some slides presented in Farnborough in the s ame way seen in the offer to Brazil, pointed to the principle “Designed to be Upgraded” what suggest the evolution of Gripen NG as a base for a pure 5th Generation fighter.

    But, even with a low RCS (a strength point of the current Gripen C/D), the design changes purposed for the NG do not walk into the direction of a stealth geometry fighter. Have I hit SAAB’s forecast Achilles’ heel? Eddy says no!

    “First of all, we don’t really believe in the total stealth value, especially if you consider the current stealth fighters in service, their technical problems and unbalanced cost-benefit. If you look at the spectrum(¹), stealth means as maybe couple of millimeters of the Wide Spectrum Combat, which is about a half of a meter if you go on infrared, radar, high frequency (…). What we try to achieve is a balanced design that let us stealthy enough over the all the spectrum, not as others being stealth in a very, very narrow spectrum. It’s really hard to go in details on this; what we’ve done, what kind of methods we’ve using, because it is not only a company secret but a national secret as well”, finish the VP, Head of Gripen Export.
    Here are some slides from Saab regarding this issue:

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    Payload does affect the RCS of a fighter. For sure. Gripen was designed to combat a soviet invasion of Sweden. Gripens were to take off from airfields with a small payload of 2-6 A2A missiles, fire their payload and return to land at dispersed road bases, re-fuel, re-arm, and go back up within minutes. That's why it had a relatively small capacity of payload and a relatively small radius compared to other fighters at that time. It was intended to fight Flankers and Fulcrums, in a scenario where resources were limited. A Gripen E does not share those features, and instead has a quite formidable range and a much bigger payload in comparison to its predecessor. For A2A-missions, the Gripen E still intends to use 2-5 Meteors and 2 IRIS-T.

    What many [well, mostly KGB] fails to recognize is that stealth is more than just angles and shapes. RAM-coating, use of special mixtures of composite material and reduction of protruding objects from fuselage are just some of many ways to reduce RCS in a certain spectrum. Saab for an instance has worked thorughly within aviation, naval and armored areas to reduce IR-signature, and they've done so very effectively.

    In terms of "stealth" there are many aspects on how to get detected. Radar emissions, com-links and IR-signatures are some of the few prominent weaknesses that can become a big factor in detection and combat. Gripen Es EW capability, Passive-mode on its radar and the silent data-fusion between other A/C are just some features that greatly aids the Gripens ability to stay undetected, or to the very least hard to detect.
    Last edited by wellerocks; 10th November 2017 at 16:47.

  16. #76
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    The Swedes claim that the Gripen has some LO features that make it have a lower RCS than any other 4th gen jet in that size range. Nobody is denying this. Not only are the Swedes saying this, they are also putting an RCS number on it.

    The problem here is, that the method/increments that the Swedes are using to come up with this number, is not the same number that the enthusiast community is using to roughly gauge RCS. (which is just the average of all the information out there.) The Swede RCS number is not an apples to apples comparison.

    But what we have is obscurantists , taking the number that the Swedes are putting out there and then conveniently claiming that the Gripen has almost as good of stealth as the Pak Fa. Which is complete and total nonsense. Apples to apples, it cannot and will not be close.

    All someone has to do it LOOK at the Gripen to see that it still is a 4th gen non stealth design. So it will not have the same RCS performance as a clean sheet stealth design.

    I could just imagine the uproar if the tables were turned. If Sweden was working its tail off, building a state of the art clean sheet stealth 5th gen jet and along came Russia with the Mig 35, claiming that it had almost as good of stealth as the 5th gen Saab.

    I cant even say that the JF-17 (a canardless Gripen with smaller wings & F-35 style intakes) has better RCS than the Gripen without an uproar ensuing.
    Last edited by KGB; 11th November 2017 at 06:56.

  17. #77
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    Its not entirely true that RCS from forums and comments are eyeball numbers. They are the average of the information that's out there.

  18. #78
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    The Swedes claim that the Gripen has some LO features that make it have a lower RCS than any other 4th gen jet in that size range.
    Is there anything else actually in its size range?
    "The early bird gets the worm but the second mouse gets the cheese."

  19. #79
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    Tejas, JF-17, MIg-21..?

  20. #80
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    Quote Originally Posted by SpudmanWP View Post
    Is there anything else actually in its size range?
    Quite a few, the LCA, the JF17, the Ching Kuo, the Mirage 2000, the F/A-50.
    The Gripen E being a bit bigger can be compared with the Viper or even the J10.

    Cheers

  21. #81
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    KGB rants on about wikipedia [something any of us can alter FYI] yet claims figures estimated by the company and the Swedish Defence Materiel Administration are bogus. Yeah, that pretty much sums up his whole discussion.


    To answer StealthFlanker; Saab are quite proud over the fact that the Gripen has a L/O in a wide spectrum. Here's an article from DefesaNet:
    Some slides presented in Farnborough in the s ame way seen in the offer to Brazil, pointed to the principle “Designed to be Upgraded” what suggest the evolution of Gripen NG as a base for a pure 5th Generation fighter.
    Here are some slides from Saab regarding this issue:
    I normally disagree with KGB but IMHO you should take these slides with grain of salt.
    Full PDF here: http://www.jsfnieuws.nl/wp-content/D...ripen_2009.pdf
    Full of contraction and questionable information me think, from the same brochure

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    Since when F-35 only carry 2 AAM?

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    Compare wing loading and Thrust loading without knowing lift coefficient and equalize combat radius?. No surprised F-15E looks so much better than F-16, F-18
    Last edited by garryA; 11th November 2017 at 15:07.

  22. #82
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    The FOI report is probably a terrible source. It's a defense research agency primer on network-centric warfare from 2001 and has very little to do with low-observable aircraft really. The quote about 0.1 sqm RCS is taken from an example on how to handle hostile aircraft incursions from a network perspective, not a detailed case study on stealth. It is stated in the Swedish text that the figures on RCS are "based on experiential evidence from FOI personnel"; given that the example uses 0.1 sqm RCS for a Gripen with a 4 AMRAAM (pre-Meteor)/2 Sidewinder loadout - we would have to assume that these figures are highly speculative if not outright useless. This is, of course, an aside to the case of the missing radar band information

  23. #83
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    Yeah there are plenty of problems with the Saab marketing brochure.

    Quote Originally Posted by garryA View Post
    Since when F-35 only carry 2 AAM?
    More importantly, who in the world would use that mission profile? It assumes that the plane needs to supercruise to the CAP area, but then it assumes the pilot wants to maximize CAP time. If so, wouldn't it make much more sense to get to the CAP area at cruise speed of around M = 0.8-0.9 so that you're not going full military thrust on the way there and the way back? You're only saving a few minutes anyway by supercruising with this mission profile, but you'd more than make it up with a longer CAP time.

    It's stuff like this that makes people not really take the Saab marketing seriously. Sounds good "on paper" to get the results they want, but makes less sense the more and more you think about it.

    Quote Originally Posted by garryA View Post
    Compare wing loading and Thrust loading without knowing lift coefficient and equalize combat radius?. No surprised F-15E looks so much better than F-16, F-18
    The 2008 RAND report claimed that the scatter plot was based on 50% internal fuel (which disadvantages higher fuel fraction planes like the F-35 and benefits lower fuel fraction planes like the Gripen). But not only that, it arbitrarily added or subtracted weight to different aircraft at whim. For example, it only added about 7400 lb to the empty weight of the F-22 when calculating T:W and wing loading when the F-22 reportedly carries 18,000 lb of internal fuel, plus the weight of weapons. It only added about 8500 lb to the F-15E when it carries over 23,000 lb of internal fuel (including from its CFT's) plus weapons. In other words, not only is "50% internal fuel" a bad assumption for comparing the performance of different planes, the scatter plot itself didn't even adhere to that! If it had, the scatter plot would have shown the F-22 to be "double inferior" (lower thrust to weight, higher wing loading) to the PAK FA, F-15C, and Typhoon, but people would've noticed that and called BS on the plot. So instead the authors arbitrarily changed the loaded weights for each aircraft to get the results they wanted.

    My favorite example of this is the MiG-29M. The authors gave it a wing loading of 70 lb/sq ft. Since the MiG-29M has a wing area of 409 sq ft, this means that they assumed its loaded weight would be 70*409 = 28,630 lb. Yet wikipedia (I know, I know...) lists its empty weight as 29,500 lb, so the loaded weight they used for it was even lighter than its empty weight! Now, granted, they might have used the stats for the MiG-29 (rather than the M variant); but the original RAND powerpoint (not the Saab) clearly states it's the MiG-29M, and not only that, the F-35 actually has pretty similar T:W and wing loading as the MiG-29! So any such scatter plot that has the F-35 not very close to the MiG-29 should immediately raise suspicions. But again, they didn't want to admit that, so they just made up numbers until they got the desired results. No wonder why RAND themselves disavowed the report shortly thereafter.

    Additionally, at the time, Saab was claiming that the Gripen E would be 15,700 lb empty with 7300 lb internal fuel. As of 2015 they were saying it would be 8000 kg with 3400 kg internal fuel, or 17,600 lb empty with 7500 lb internal fuel, an increase of 12% to its empty weight, with the requisite decrease to its flight performance. Who knows what they're claiming now...
    Last edited by Vanshilar; 13th November 2017 at 23:26.

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