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Chinese J-20 and J-31 5th Generation Fighter Jets

Discussion in 'China & Asia Pacific' started by Martian, Dec 23, 2010.

  1. smestarz

    smestarz Lt. Colonel REGISTERED

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    I think we are away from topic of J-20 and talking something that is not really related to j-20 but talking abt F-35 and EFT.
    Now here are some of my views.

    Technology will always improve on itself exponentially, so, you see we have so many generations of planes, but there would be a time where there would be very little development in design and material (almost like now) but then there might be some radical new find and that exponential curve is redrawn for longer life and development in that case.

    Like most of us here say Stealth is very important for the survival of the plane, but Stealth is not going to be THE TECHNOLOGY, there would be some ways that Stealth will be detected. F-35 is VLO not Stealth.
    Frankly, would a plane that is detected by IR be actually termed as Steatlh?

    Stealth is stealth now, but in few years it might be superseded by technology that can detect it, and then all this investment in Stealth will have nothing to show for.

    I would believe I am school of thought where the basic design of fighter should be based on Aerodynamics for maneuverability and Speed (when possible) this what can make the plane an actual plane. the ability to out turn its opponents.

    Now, to enhance the planes ability, you can add technology that can be possibly fitted in modules, so as to not disturb the basic design of the plane. these modules should be possible to update so as to create a better detection and self protection.

    Looking at F-35 design, everything the shape etc has been designed to make it VLO, but that is now, but by the time it arrives on the scene, there might be few radars that can not only detect but also track this bird with ease, so what does this bird do?
    USA has good technology, but its not that they are the only country who has technology or rather they are not the only country developing it.


    Also i was thinking something else,
    We are always talking of trying to make the plane Stealth so that it is invisbile on radar, but there can be some ways such as
    1. When the enemy radar waves are sensed the system detects and analyses the signal and then transmits the signal out of phase, thus possibly giving no blip but this might need very serious computational power,

    2. Second thought might be rather than keep silent, the moment the plane detects enemy Radar waves, it starts to transmit in all possible wavelengths. (if you are detected when silent, why not just start singing)

    3. Third might be some sort of POD, that is deployed when over an enemy territory, that has pack of 4 missiles designed to be unstealthy, and when the detection is done for a long time. these missiles are deployed, and these missiles fly in different directions giving off heavy signal and thus creating a multiplied force for the radar to detect. Hnece the plane can either be lucky enough to evade or at least the enemy will end up deploying planes over a false alarm.

    If you cannot hide, you might as well show off, and do it in such a way that the enemy gets confused as to what exactly is happening.
     
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  2. G777

    G777 Lt. Colonel ELITE MEMBER

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    Agreed. Typhoon relies on survivability and is mainly for country defence.
     
  3. gambit

    gambit FULL MEMBER

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    Your source have at best an incomplete, if not false at worst, understanding of how to exploit different shapes' responses from radar bombardment.

    I will clarify...

    [​IMG]

    When a radar signal impact a curvature, such as found on a sphere or cylinder, there is ALWAYS a tiny amount of flat surface that will reflect a tiny amount of signal back to source direction. That amount is called 'specular' signal reflection, or specular reflection for short. If the sphere or cylinder is rotated, there will ALWAYS be that tiny amount of specular reflection and signal strength is constant throughout rotation. Most of the radar signal will become surface wave behaviors.

    On the other hand...

    [​IMG]

    When a plate is rotated, there will be a point where the plate's signal reflection strength is highest (perpendicular) and lowest (edge).

    This make the plate the body with the higher RCS overall in terms of both signal strength (perpedicular) and signal characteristics (scintillation).

    Scintillation:

    Scintillation (radar) - Wikipedia, the free encyclopedia
    Between the rotating sphere and the rotating plate, the sphere's constant low level specular reflections will most likely be discarded as part of background radiation while the plate's predictable fluctuation in amplitude (from perpendicular to edge) will be noticed and tracked, even if the edge reflection is lower than the sphere's specular reflection. The radar will note that for every high (perpendicular) there is a low (edge) followed by a high (perpendicular) followed by a low (edge) and so on...

    Further...

    [​IMG]

    If we take a look at the F-117, we see many plates joined together and each joint is a surface discontinuity. If we want to minimize 'off surface' radiation, in other words, since we are dealing with a finite body and if the goal is to keep as much of the radar signal on the surface for as long as possible, then we must minimize surface discontinuities as much as possible. If we cannot avoid surface discontinuities, such as with canopies, weapons and landing bay doors, and access panels, then we must redirect those off surface radiation via 'saw tooth' edge treatments to minimize their return to source direction. Minimize, not eliminate.

    That is why we moved away from the angled faceting (plates) method of the F-117 and incorporate curvatures into the B-2, F-22, and F-35. We want to induce surface wave behaviors for as long as possible so our absorber can work to produced low level 'leaky' waves, then when whatever remain has to leave the aircraft -- because it is a finite body -- those edge diffraction signals will be so low that hopefully they will be dismissed as part of background radiation.

    It is the judicious use of angled facetings when applicable and curvatures when applicable. It is not as simplistic either-or as your source made it out to be.
     
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  4. satya

    satya Lieutenant FULL MEMBER

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    Gambit you are a very nice addition to the forum, i really appreciate the your contribution
     
  5. MiG-23MLD

    MiG-23MLD Major SENIOR MEMBER

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    [​IMG][​IMG]


    J-31
    [​IMG]
    I think you are not understanding my point, flat surfaces are good for concentrating the reflection into just one direction thus the reflection in that direction is stronger than the one of rounded surfaces but it goes to a narrow angular section, some reflection will go back to the radar, but its reflection back to the radar will be lower as long as the angle is not 90 degrees.

    Round surfaces reduce the reflection strength because they distribute the reflection into a wider angular section but the reflection goes to a larger angular section thus it it is more detectable from a wider angular section


    By the way the sources are not wrong, simply explain a reality stealth unpairs aerodynamics
    [​IMG]
    [​IMG]

    http://www.rfcafe.com/references/electrical/ew-radar-handbook/radar-cross-section.htm

    The sphere is essentially the same in all directions.

    The flat plate has almost no RCS except when aligned directly toward the radar.

    The corner reflector has an RCS almost as high as the flat plate but over a wider angle, i.e., over ±60°. The return from a corner reflector is analogous to that of a flat plate always being perpendicular to your collocated transmitter and receiver.http://www.aerospaceweb.org/question/electronics/q0168.shtmlSquare trihedral corner reflector Strongest radar return due to triple reflection of incident wave
    Right dihedral corner reflector Second strongest radar return due to double reflection of incident wave; decreases from maximum slowly with changing θ and rapidly with changing φ
    Flat plate Third strongest radar return due to direct reflection of incident wave; decreases rapidly as incidence angle changes from perpendicular
    Right circular cylinder Strong radar return as aspect (θ) changes, but decreases rapidly as azimuth (φ) changes
    Sphere Produces the same isotropic return in all directions
     
    Last edited: Oct 30, 2012
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  6. hitesh

    hitesh REGISTERED

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    Chinese planes are copy cat trash. J20 is neither stealth nor 5th gen
     
  7. MiG-23MLD

    MiG-23MLD Major SENIOR MEMBER

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    [​IMG][​IMG][​IMG][​IMG][​IMG][​IMG][​IMG][​IMG]
     
    Last edited: Oct 30, 2012
  8. MiG-23MLD

    MiG-23MLD Major SENIOR MEMBER

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    [​IMG][​IMG][​IMG]
     
    Last edited by a moderator: Mar 12, 2014
  9. MiG-23MLD

    MiG-23MLD Major SENIOR MEMBER

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  10. Picard

    Picard Lt. Colonel RESEARCHER

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    So, F-22 and PAK FA copies?
     
  11. MiG-23MLD

    MiG-23MLD Major SENIOR MEMBER

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    [​IMG] PAKFA is an original design.

    The chinese copied the F-22 and F-35 with inferior jet engine technology.

    J-20 has no TVC and Al-31s and J-31 has RD-33


    [​IMG]
    [​IMG]
     
    Last edited: Nov 2, 2012
  12. MiG-23MLD

    MiG-23MLD Major SENIOR MEMBER

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    [​IMG]

    best ever picture of J-20
     
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  13. Picard

    Picard Lt. Colonel RESEARCHER

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    I know that PAK FA is an original design, what I meant was that Chinese have merged F-22 and PAK FA to form J-20, and copied F-22 for another.
     
  14. MiG-23MLD

    MiG-23MLD Major SENIOR MEMBER

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    [​IMG][​IMG][​IMG]

    In my opinion the Chinese can not copy T-50 first because T-50 has variable geometry intakes which means it flies faster, plus it has TVC nozzles, the chinese fighters lack that too.


    China only copied superficially the american aircraft and MiG-1.44 in the wing-canard-tail arragement

    [​IMG]
     
    Last edited: Nov 2, 2012
  15. G777

    G777 Lt. Colonel ELITE MEMBER

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    I prefer stealth aircraft to concentrate reflection in less directions as possible, which is why I dont like rounded areas or jagged bits. Radar deflection is almost like a light with a mirror aint it. Shine a light on a flat mirror and deflect the full beam in one direction, sphere mirror scatters the light in a wide area thus loss in light intensity but some still light comes back to the source. A jet headon is a cone shape and thus nothing can really come back to the source.

    Thats just the way how I have always seen it. Except radar ofcorse can go through objects which is why they try to make advanced stealth coating.
     

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