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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. Gessler

    Gessler BANNED BANNED

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    J-20 maybe able to carry a higher payload, but F-35 due to its powerful electronic warfare and radar
    is likley to gain the upper hand because of greater chance of jamming the SAM radars, as it is neither of
    these fighters looks capable enough for outmaneuvering or fooling a modern SAM system like S-400 once fired upon.
     
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  2. Picard

    Picard Lt. Colonel RESEARCHER

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    @G777 No idea. I'd have to know their comparative wing loadings and thrust to weight ratios at 50% and 100% fuel to answer that... because against VHF radars, both will get detected.
     
  3. G777

    G777 Lt. Colonel ELITE MEMBER

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    You have got a good point there. Exactly what I was thinking, though we dont know what the J-20 has for electronic warfare.

    Even if a jet dont jam missiles that well it will be enough to screw up the missiles direction to avoid being hit. Thats where the J-20 gets the advantage in that area. It may not have powerful engines, but its got canards and large wing area, also the stealth although some are skeptical is said to be better or eqaul to the F35, though I expect thats at the front and sides and not the back.
     
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  4. Manmohan Yadav

    Manmohan Yadav Brigadier STAR MEMBER

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    but the canards always raise doubt in my mind,
    just how much RCS do they compromise for J-20.
     
  5. G777

    G777 Lt. Colonel ELITE MEMBER

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    Fly in a straight line and they will be fine. :smoking1: but if they really want to fly about without too much RCS then they need TVC. When canards move they can deflect radar in different directions. If they stay still then they cant do that.

    TVC on the Eurofighter would also reduce its RCS.
     
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  6. Manmohan Yadav

    Manmohan Yadav Brigadier STAR MEMBER

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    Yes, but i dont remember seeing any signs of TVC on J-20
     
  7. MiG-23MLD

    MiG-23MLD Major SENIOR MEMBER

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    All aircraft experience a loss of control effectiveness at supersonic speeds. To generate the same maneuver supersonically as subsonically, the controls must be deflected further. This, in turn, results in a big increase in supersonic trim drag and a subsequent loss in acceleration and turn performance=higher RCS at supercruise too


    JUST HOW GOOD IS THE F-22 RAPTOR? Carlo Kopp interviews F-22 Chief Test Pilot, Paul Metz

    This, it believes, would provide data to back up its claims that TVN could reduce fuel burn on a typical Typhoon mission by up to 5%, as well as increase available thrust in supercruise by up to 7% and take-off thrust by 2%.

    Eurojet pushes thrust-vectoring technology for Typhoon

    According to Russian sources J-20`s engine are WS-10s or Al-31, no TVC nozzles

    So very likely it does not supercruise the Russians said in 2010 China asked 117s engines to Russia.
    Russia said no 117 engines without Su-35 and large order

    Su-35 supercruises and has TVC nozzles with a 100km detection range in IRST and 400km radar detection range is probable J-20 is a F-35 type aircraft
     
    Last edited: Sep 15, 2012
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  8. G777

    G777 Lt. Colonel ELITE MEMBER

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    If the Chinese military truly believe that the J20 is stealthy then will make it even stealthier by adding TVC. TVC would have like a stealth setting where TVC controls aircraft mainly for flying about once in flight, however in combat and other situations the canards and other surfaces would work, though this is just speculation of what they could do with the TVC. Eurofighter was to have different settings if it used TVC, back ups and such.
     
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  9. G777

    G777 Lt. Colonel ELITE MEMBER

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    Well they better not turn much then with those giant canards, which is why I said they will be okay if they fly in a straight line. Though they will have to turn tail sometime.
     
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  10. gambit

    gambit FULL MEMBER

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    The issue is less about the canards' movements, although the movements do matter, but more about the QUANTITY of radiators.

    How many structural EM radiators does a sphere has? Just one -- its continuous surface.

    How many structural EM radiators does a cube has? All the sides and edges. Count'em.

    Same for the pyramid or the pentagon or just about anything non-spheroidal. Anytime you have a 'surface discontinuity' such as a gap or an edge, you have an EM structural radiator.

    The goal of 'stealth' is to reduce the overall quantity of these radiators. Unfortunately, we do not use the sphere as a fighter aircraft. The sphere is the best 'stealth' shape because it produces only one mode of radiation that can be directed back to the seeking radar -- specular.

    Specular reflection is that initial amount of surface reflection that all bodies produces. Even an edge have a small amount of surface area that is directly facing the seeking radar. Very small. The sphere produces other modes of radiation in the form of surface traveling waves that are mostly away from the seeking radar's position.

    Like this...

    [​IMG]

    It is only the 'creeping wave' behavior that can increase the sphere's RCS, but if the diameter is greater than ten wavelengths, the creeping wave behavior will not exist. Wavelength is represented by the Greek word 'lambda'. This rule is called the 'ten lambda rule'.

    Since we do not have a sphere for a fighter aircraft but a conglomeration of shapes of different sizes in a mass, the goal then is to do as much as possible to reduce the quantity of structural radiators of those different sizes. If we cannot reduce the quantity then we should try to reduce the sizes. Unfortunately, a canard is usually an active flight control element whose shape and size are dictated by aerodynamic demands and whose existence is demanded by the aircraft design itself. This is the flying wing design like the B-2 have the lowest RCS compare to its physical size. The flying wing have far less major structural radiators than the Cessna 152 and on any radar, a much lower RCS because of that.
     
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  11. MiG-23MLD

    MiG-23MLD Major SENIOR MEMBER

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    [​IMG] Cassidian, the defence and security division of EADS, has developed what is known as "passive radar" that can locate even difficult-to-detect flying objects such as stealth aircraft and that itself is practically undetectable. In contrast to conventional radar, passive radar doesn't emit any radiation, but instead analyses radiation reflections from other emitters, such as radio and television stations, to detect objects.

    "The principle of passive radar has been known for a long time," says Elmar Compans, Head of Sensors & Electronic Warfare at Cassidian. "However, we have now integrated the latest capabilities of digital receiver and signal processing technology to significantly enhance range and detection accuracy by monitoring various emitters at the same time."

    further readAsian Defense: "Passive Radar" from CASSIDIAN Remains Invisible

    [​IMG]


    +


    [​IMG]

    could F-22 and by default J-20 being beaten by the Eurocanards, Su-35 and obviously T-50

     
    Last edited by a moderator: Mar 12, 2014
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  12. Gessler

    Gessler BANNED BANNED

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    Thanks for the informative post Gambit.

    So I believe that the gap between the canard and the main wing's leading edge root is a typical surface
    discontinuity right? So lemme consider this example, if and when the F-22 and J-20 happen to be built
    out of, and coated with the same signature-reduction materials, and then when probed from below (as is the
    case with most ground-based radars) the J-20 will have a higher RCS due to the additional electromagetic
    radiators that are inherent to that airframe when compared vis-a-vis the F-22. This would
    also apply (although to a lesser extent I believe) when scannned by fighter-based radars.

    Let me know if I have rightly understood the concept here.

    Secondly, this would also mean that if the F-117A was built out of the same materials as F-22 and sent to
    fly over a radar station, the Nighthawk would turn out be far stealthier than the Raptor due to the
    much lesser EM radiator hotspots on the F-117 airframe...
     
    Last edited: Sep 15, 2012
  13. trendmaker1

    trendmaker1 REGISTERED

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    india may need more powerfull radar of these types after j 20 will complete its protection.:no:
     
    Last edited: Sep 16, 2012
  14. Picard

    Picard Lt. Colonel RESEARCHER

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    Better IRST + passive radar would be a more logical choice... why brute force through a wall when you can simply walk around it?
     
  15. trendmaker1

    trendmaker1 REGISTERED

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    i agree with you but we should also focus on defensive mediums...
     

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