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

Discussion in 'World Armed Forces' started by A Bar Brother, Dec 23, 2014.

  1. Anlsvrthng
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    Anlsvrthng Senior Member
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    I think I see the problem here.

    There is no "military antenna" or " radar antenna" or "civilian antenna".


    There is only a single design and single principle how anyone can generate electromagnetic waves, about the calculation of beam width , side lobes , detection ability and jam resistance.


    Any secure, non detectable and non jammable long communication system must use directional antennas, and in the case of a mobile platform automatic (preferably electronics) steering.


    It can be either mechanically steered YAGI / parabolic antennas, or electronically steered phased array antennas.

    Neither of them is special by any means, lot of guy makes this kind of stuff as a hobby at home.

    Actually, anyone who can make a radar can make this kind of com system as well, considering that it is a cheap/ dumbed down radar.

    And still, I am very interested about the F-35 radar performance calculation : )
     
  2. Brumby
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    Brumby Major

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    There you go again with a bunch of comments that have no logical or causal relationship to the subject of discussions i.e. communications and jamming. This will be my final attempt and then I am out of this senseless conversation.

    Jamming of communications is the same as with jamming of radar.

    upload_2019-10-3_21-20-44.png

    Jamming involves the transmission of unwanted signals to a target receiver to interfere with its ability to receive the desired signals .It is about the jamming-to-signal ratio (J/S) which is the ratio between the receive power of the jammer and the desired signal in the target receiver

    upload_2019-10-3_21-24-44.png

    The jamming signal has to overcome the receiving signal and when that threshold is reached it is known as "burn-through" The other thing to note is that the jamming signal has to be of the same frequency as the receiving signal. This is it. Not the bunch of stuff that you said that has no relationship to the subject.

    That said what would it involve to jam a MADL transmission? As previously pointed out, if you don't know the presence of an F-35 and if it is transmitting stealthily there is no jamming - period. Even if you know its location, it is difficult to intercept its communication unless you are in line of sight but since the communication is directional you have to know in which direction it is beaming the message. You can attempt to flood the airwaves through barrage jamming at stand off distance but this will create fratricide. Finally, MADL operates in Ku band and that means it has a frequency band width of 6.5 GHz (12-18.5 GHz). That is a huge bandwidth to jam and a lot of jamming power is required. In contrast, Link 16 operates in the UHF frequency which only has a bandwidth of 700 MHz.

    AN/APG-81's detection range is classified and so there is no official number. A range has surfaced over the years from different sources and is between 180 to 250 km against a 1m2 RCS target. I basically took a conservative number of a lower range of 180 to 200 kms and apply it against the SU-57 RCS of 0.5m2. I then used a simplified version of the radar range equation to derive the detection range based on the following formula :
    .
    R1/R2 = (RCS1/RCS2)^(1/4)

    Nothing magical..
     
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  3. Anlsvrthng
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    Anlsvrthng Senior Member
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    It is not hard to recognise that the documents talk about high frequency directional antennas.


    It is phased array antenna, with electronic beam steering, keeping a relatively narrow beam on the other aircraft.

    Work like a simplified radar, with magnitude lower energy and wider beam.

    It require directional jammer, like a YAGI antenna pointed to the aircraft and emitting a narrow beam of high energy jamming signal - it is not prefered method, the long YAGI has a narrow bandwidth , phased array more preferred in this regards.

    It is not something esoteric or hard to design, the UK radio amateur rules directly define the maximum transmission energy for dipole, and the radiation energy in the case of a directional antenna can not be higher that the dipole radiation in the same surface cross section.

    This is not an esoteric science, any radio amateur with full license can construct a jammer proof directional antenna for you (maybe not with active electronic beam steering, but it is more of a cost constrain than anything else )



    Your assumptions without background or support fact:
    1. F-35 radar cross section
    2. Su-57 radar cross section.

    Just for clarification, the MIG-21 has 1-3 sqm radar cross section.

    You say that the same industry half century later designed a marginally better radar cross section air plane than the MIG21?

    The best part of hig RCS data comming from the analysis of the prototypes, and those was designed for other purposes than to test the RCS (more likely there is a few non-flying RCS testbed airframe never seen by the public )

    Not considered important data:
    1. Su-57 has bigger radar, roughly twice as bigger (in area) than the F-35 .
    2. Due to the above the Su-57 has square root 2 longer wavelength than the F-35 radar ( it has the same emitter count) means the radar cross section of the F-35 bigger on this wavelength than on the frequency used its own radar.
    3.Due to no1 the Su-57 has higher radiation amplitude and twice bigger aperture than the F-35

    So, issue with the logic:
    1. the Su-57 radar more capable due to nose diameter and geometry than the F-35 radar
    2. If we say that the two aircraft has magnitude similar radar cross section then the Su-57 has an advantage in detection range.
     
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  4. Inst
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    Inst Senior Member

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    I notice this hasn't been posted yet; i.e, Chinese interest in at least evaluating the Su-57.

    http://www.globaltimes.cn/content/1163033.shtml

     
  5. taxiya
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    taxiya Major
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    It is a Global Times author HIMSELF and his unnamed "expert" interested in evaluation and wanted to buy using NOT his budget money. That's all. It is so strange that some people today still have the kind of mind-set of "buy everything from anybody" as if 1. China is always inferior of everything and 2. Chinese money is unlimited. A mindset of inferior syndrome plus parvenu.

    The point is, knowing the others is always good by all means. If buying just ONE is possible, do it. Unfortunately that is never going to happen. Buying a bunch is simply crazy and not worth it.
     
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  6. ougoah
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    ougoah Senior Member
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    Well it all depends on effective they are but it is doubtful that the Su-57 is overall going to be as useful to the PLAAF as the J-20 is. For one thing Su-57 will only be compatible with Russian weapons. So then it becomes a matter of price. Su-35 does the job of having some "non PLAAF" fighters for SCS, Japan, and India missions. The Su-35 is more capable than everything regional airforces have and 24 of them can pretty much take air superiority on a limited conflict already.

    Since that role is already taken, where's the need for Su-57? J-11D onwards will benefit from having used Su-35 and knowing if supermaneuverability is worth pursuing. Not so much pulling it apart since the superficial aspects have been learned decades ago, the important stuff worthy of studying and reverse engineering is impossible to do i.e. engine specifics, FCS, any Russian sensor fusion, and other software. Flight control with TVC was demonstrated by CAC in J-10 performance. It's a different approach to TVC to the more expensive Russian method apparently (according to this forum's materials) but it proves CAC at least alone is capable of creating FCS for a TVCed version of J-10. Whether SAC can or wants to for future Sino-flankers, who knows, but having Su-35 helps PLAAF answer this question for SAC, at least in part - supermaneuverability.

    I doubt Su-57 will be ordered in large numbers either since that represents an opportunity cost to acquiring more J-20s or using that money to further domestic industry. Therefore no Su-57s will be purchased unless the Russians are happy to let China buy just 12 or a very limited run purely so China can study them and find out what it's capable of from operating them. This may damage Russia's chances at making big sales to India in future.
     
  7. anzha
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    anzha Junior Member
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    Lots of juicy bits to be seen in the background there.
     
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  8. Hyperwarp
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    Hyperwarp Captain

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    052 with one Izd.30 engine,

    [​IMG]
     
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  9. Hyperwarp
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    Hyperwarp Captain

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    New short-range missile for conformal pods? Looks like a R-77 cut in half o_O

    [​IMG]
    [​IMG]
    [​IMG]
     
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  10. TerraN_EmpirE
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    TerraN_EmpirE Tyrant King

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    Could be bust just as likely to replace the close range missiles used in the bays.
     
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