J-20 5th Gen Fighter Thread VI

Discussion in 'Air Force' started by siegecrossbow, Sep 4, 2017.

  1. Tam
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    Tam Captain
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    Much ado about nothing.

    Do you have any idea that the J-20 maneuvers that were allowed in the public had to be approved in the first place?

    That means very likely they were only allowed to show the capabilities of the J-20 up to this point, and they are not allowed to show the full capabilities in the first place, and the maneuver is there to match a script.
     
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  2. Bltizo
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    Bltizo Moderator
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    It's not a straw man, because those are the roles that were ascribed to the aircraft. I wasn't the one that applied it.


    Do you accept that there were various mainstream defense media writers and commentators after J-20 was unveiled that argued J-20's design limited it to the role of a dedicated interceptor or a dedicated striker?




    An air superiority fighter can conduct interceptor profile missions like what you've described.

    As an air superiority fighter with other roles including as interception and strike, I fully expect J-20 to train to use interception tactics among various other tactics.


    Yes, air superiority fighters requires the ability to seize and hold air superiority.
    Straight from AVIC:

    [​IMG]

    "Major operational missions include: seizing and maintaining air superiority, medium and long range fast interception, escort and deep strike."





    I've been consistent in arguing that J-20 should have a secondary strike role if the requisite munitions are designed for its weapons bays.

    I've never argued that J-20 is an aircraft that is "not a pound for air to ground".

    See my post from #5392 above:

    "I am stating that J-20 is a general air superiority fighter that is capable of conducting other roles such as of interceptor and strike duties, which is a perfectly reasonable way of summarizing the current body of evidence and statements of what roles it is designed to be capable of conducting."

    https://www.sinodefenceforum.com/j-20-5th-gen-fighter-thread-vi.t8169/page-540#post-563663


    Let me be simple and clear:
    My position is that J-20 is an air superiority fighter whose other roles also include interception and strike.


    If you make further statements suggesting that I believe J-20 is not intended to be capable of doing the interception mission or that J-20 is not intended to be capable of doing the strike mission, then I can only be left to interpret that you are arguing from a position of bad faith.
     
    #5402 Bltizo, Jul 27, 2019
    Last edited: Jul 27, 2019
  3. ZeEa5KPul
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    ZeEa5KPul Junior Member
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    I'm not too concerned about the "network-centric warfare" thing - China has an excellent and fast-improving military electronics industry, and when it comes to weapons it's the US that's playing catch up with the AIM 260. The VCE is a strong counterargument, though. Do you have a handle on when China's VCEs will come into play?

    Maybe not in general, but the coupling phenomenon I pointed out is corroboration of the design objectives Dr. Song outlined in his paper, which strengthens the claim that high manoeuvrability is a core attribute of the J-20, which in turn lends support to the air superiority hypothesis.
     
  4. Tam
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    Tam Captain
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    What does this has to do with being an interceptor, dogfighter or a general air superiority fighter? You only talk about sustained turn rates without factoring that instantaneous turn rates are going to be more important.

    Running canards no one puts on a stealth aircraft? Oh? Boeing's six gen proposal.

    1020790304.jpg


    Stealthy canards is not about where it is coplanar with the wings, but when the edges of the canard has the same angle as the main wing. When you have two surfaces of the same angled direction, they appear as one on radar because the reflections on either two, would be the same.

    Your coplanar approach would not work simply because radio waves have a way of propagating across surfaces and they would hit the back wing nonetheless. Here once again, the leading edge of the main wing should be the same as angle as the leading edge of the canard. Two edges with the different angles would result in two directions of scatter instead of one, and that's less stealthy.

    The least stealthy thing on the J-20 is actually the LERX, as the leading edge has a different angle from the canards and the wing, and you have to use the canards and the DSI in a way to lessen the wave propagation to the LERX.

    Having the canards at the same plane as the main wing risks turbulence from the canards to the wing, and lessens fresh air flow to the leading edge of the main wings.
     
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  5. Inst
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    Inst Senior Member

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    @Tam

    As I've said before, the J-20 needs to ditch its tailfins and strakes. Note how on the Boeing 6th gen canard fighter, the strakes and tailfins are out as well.

    http://www.nasa.gov/sites/default/files/images/353809main_EC96-43641-8_full.jpg

    Until the J-20 gets TVC and dumps its strakes and tailfins, I don't see the J-20 as being able to compete with American 5th gens in symmetric stealth.

    Another problem pointed out is that the canards impact side stealth, and from simulations they seem to create hotspots at particular angles. It doesn't mean that the J-20 has bad stealth at other angles, but it complicates and makes all-aspect stealth much more difficult.

    ===

    As for the J-20 turn video, what I find most exceptional about it is that it's a very hard turn wherein the aircraft seems to lose energy (i.e, ITR), and the afterburners are fully on. It's much more indicative of the J-20's limitations than any other video we've seen.
     
  6. Tam
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    Tam Captain
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    Every plane loses energy on a hard turn. Actually you being a delta, you can potentially lose more energy than a conventional wing. The advantage of canard-deltas are in their instantaneous turn rates along with fast rolls thanks to a high degree of elevon authority.

    I am not sure if canards would impact side stealth if the edges have the same angles as the main wings. Regardless of direction, if both edges have the same angles, they would appear as one wing. If you have more problems with that, build the canard out of composite metamaterial.

    Strakes and tailfins?

    The F-22 and F-35 has their tailfins. Maybe in the next generation you may eliminate them but that would affect maneuverability. You can leave this up to the sixth generation of fighters.

    The strakes are in the FB-22. Never mind turning the inlets that way came from the F-35.


    fb_22_1.jpg
     
  7. Inst
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    Inst Senior Member

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    I've already put out the bad faith accusation on you, so if you regard me as such, it's just turnabout as being fair play. But let me talk about the dedicated interceptor straw man:

    No talk about "dedicated" interceptor.

    http://www.ausairpower.net/APA-J-XX-Prototype.html

    https://www.wired.com/2011/01/dont-panic-chinas-new-stealth-jet-takes-to-the-air/

    Agility is prefixed with "perhaps", and the statement about the F-22, when we consider the underpowered engine and the TVC advantage of the F-22, is fairly reasonable. More problematic is the "fighter-bomber" statement, but this is based off incorrect information as the difference between China-watchers amateurs and professional analysts is that while both sides came to the 22 meter conclusion immediately, the professional analysts took more time to realize the J-20 was shorter and wider than they thought.

    In both sources, nowhere is the J-20 described as a dedicated interceptor or strike aircraft. That's your words that's being piled on.

    And as far as the AVIC sign goes, it, notably, is not describing the J-20 as an air superiority fighter, but rather as a heavy 5th gen aircraft that can seize air superiority, intercept, escort, and deep strike.
     
  8. Inst
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    Inst Senior Member

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    @Tam ,

    The FB-22 does not have the ventral strakes that are present in the J-20.

    As far as removing the strakes and tailfins, the J-20's aerodynamic design is already advanced enough with its dihedral lerx canard lerx anhedral wing configuration that once you put in TVC, get the flight regime and TVC to be mature and reliable, you can just lop off the strakes and tailfins. It's not going to be true 6th gen performance, but you have enough advantage there.

    I'll also point out that the J-20 wing configuration is creating corner reflectors:

    upload_2019-7-27_2-52-21.png

    This likewise shows up from a frontal view.

    [​IMG]

    ===

    Basically, the ideal stealthy shape is a diamond of some kind. The more you diverge from it, as with adding canards or for that matter having tailfins, the less stealthy you get. But these things can cancel each other out, i.e, canards without tailfins is as stealthy as tailfins without canards.
     
    #5408 Inst, Jul 27, 2019
    Last edited: Jul 27, 2019
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  9. Tam
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    Tam Captain
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    I am talking about the intake forming strakes that are part of vortex formulation.

    I already mentioned the LERXes are a problem. But the reflections you described, isn't going to work at all since the canards and the wings are in the first place, not coplanar.

    This is more a problem if the canards and the wings are coplanar like you strangely suggested, and I quote:


    I don't disagree with this. The stealthiest shape is one with the least directions of scatter, preferably one. That means all the angles in your aircraft have to be reduced. The canards, the wings and the tailfins all have the same angle on the J-20, but I pointed out that the leading edge of the LERX has a different angle.

    But for them to introduce LERX and not delete that feature at all --- its entirely possible, see MiG 1.44 --- that means maneuverability remains important for the designers that they are willing to sacrifice some stealth from that.

    In fact the whole J-20 design pays great attention to vortex formulation, and it has many vortex creators, and the vortex layers are smooth and well organized even at high AoA. The whole point of paying such high attention to this is for high AoA instantaneous maneuvers.
     
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  10. Bltizo
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    Bltizo Moderator
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    Just for the record, I've replied to this via a PM
     
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