PLAN dedicated carrier-borne AEW Thread (KJ-600 or KH-600)

Discussion in 'Navy' started by delft, Jul 7, 2017.

  1. Bltizo
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    Bltizo Lieutenant General

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    The JZY-01 is thought to have been derived from the Y-7, but let's set this aside for now and presume that H-600 has no influence from Y-7/was not derived from it etc.


    I've been talking about the airframe+powerplant. If they wanted a turbofan powered AEW&C, I don't think anyone believes they would use the same airframe as what the E-2/H-600 uses -- and choosing a new airframe configuration vs the proven E-2 arrangement adds risk. This is in addition to having a viable powerplant that they could adapt for it.


    Of course, I fully agree that turboprop driven aircraft have their advantages for a carrier based AEW&C and is almost certainly one of the reasons for going for a turboprop driven AEW&C.
    But I believe the lower risk of developing a turboprop driven airframe similar to the E-2 was also a factor for the final design they went for.
     
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  2. Iron Man
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    Iron Man Captain
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    The Yak-44 was developed with the Ulyanovsk class in mind, which in terms of flight deck size and flight ops was very similar to the Nimitz class, so the basis of comparison is perfectly appropriate as far as ships are concerned. As far as range and fuel efficiency is concerned, it's a matter of physics. Turboprops outperform turbofans at the speeds at which a carrier-based AEW/C aircraft is expected to fly. And in terms of aircraft design, the endurance of a given AEW/C design is one of the most if not the most paramount design criterion. Which means if you're going to design a carrier-based AEW/C aircraft, you will choose turboprop regardless of whether you're American or Russian. I have no doubt it is a pain in the ass to operate a relatively weak turboprop-engined, wide-winged aircraft on a flight deck filled with overpowered jet fighters, so the bar for their inclusion IMO was always going to be pretty high. Despite that both countries chose very similar designs. Why? Because wide, thin (high aspect ratio) wings combined with turboprops allow you to maximize fuel efficiency. And fuel efficiency in an AEW/C is what it's all about.

    No. The Viking AEW was a LM-funded proposal to the USN which was not solicited by any USN requirement to replace the E-2 with a specifically turbofan-based AEW. The USN wasn't even remotely interested in the concept.

    Right, and the PLAN rejected the JZY-01. If it were all about risk reduction, an entirely brand new design certainly doesn't seem to be lower risk than a modification of an established plane. In words, the Y-7 is as I said, unsuitable for modification into a carrier-borne AEW.

    No, I think they would use a very similar airframe, regardless of choice of turboprop or turbofan. See my answer to terran_empire above. Again, outside of the PLAN obtaining the E-2's blueprints, there is no risk reduction associated with a turboprop over a turbofan, especially in a clean-sheet design for which the PLAN has no prior experience. Just because you can observe the external characteristics of an E-2 doesn't mean you somehow reduced any risk for the H-600 program by choosing a turboprop, just because the E-2 uses it.
     
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  3. Bltizo
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    Bltizo Lieutenant General

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    To my knowledge the JZY-01 was not intended to be an airframe intended for service but a demonstrator..


    Okay, well in that case the underlined part would explain where our opinions differ.

    I personally do not think the airframe of a turbofan powered AEW&C would have a similar configuration to E-2/H-600, partly because I cannot think of any turboprop (or propeller) driven aircraft which had turbofan (or even jet) propelled variants and enjoy meaningful service lives. Things like wing sweep, landing gear arrangement (which in turn could have consequences for fuselage diameter), would likely all be rather different for a turbofan "variant" of H-600 such that it would be a different aircraft.
     
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  4. Iron Man
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    Iron Man Captain
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    Well, you can't have your cake and eat it too. Either it was an attempt to adapt the Y-7 to a carrier-borne AEW role, in which case it failed and my point remains, or it was just a technology demonstrator, in which case the association with the Y-7 is irrelevant to the entire discussion.

    The wing sweep depends on the aircraft's intended role/speed, not the engine. Swing wing fighters are perfect examples, being turbofan-driven aircraft yet with highly unswept modes for maximum lift and fuel efficiency, and highly swept modes for high speed dashes, which an AEW/C aircraft will never experience. As for the landing gear differences, they really wouldn't amount to much at all. If you are claiming that the landing gear would be located in the fuselage for a turbofan AEW/C instead of underneath the turboprop housing, maybe, maybe not. Even if they were located in the fuselage you would still see the same wide, thin, high aspect ratio wing, the same thin fuselage with maybe a bulge at the bottom rear for the landing gear (or not even), and the same multiple stubby aft vertical stabilizers which are an inevitable consequence of the radar dish. In other words, a turbofan-driven AEW/C with the same appearance as the E-2 and the Yak-44. Which again, still gives you no risk-reduction at all because you don't have access to the blueprints for either of these aircraft, so you are starting with a clean-sheet design regardless of whether you chose turboprop or turbofan.
     
  5. Bltizo
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    Bltizo Lieutenant General

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    I think my original point was that H-600 could be substantially modified from the Y-7. At this stage we don't yet know just what exactly H-600 will look like and how much commonality it has with JZY-01, however it almost certainly would have been informed by JZY-01.


    What you've just described to me sounds like a very different aircraft in configuration and aerodynamics to the E-2/H-600, so we will just have to agree to disagree here.
     
  6. Iron Man
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    Iron Man Captain
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    And yet the CGIs of the H-600 (which I believe I read somewhere earlier in this thread that you thought were representative, yes?) do not look anything like a "substantially modified" Y-7, unless by "substantially modified" you actually mean nose and tail completely redesigned and fuselage and wings massively shrunk down in size. And of course the airframe would have to be significantly reinforced for cat launches and trap landings, along with a complete newly designed nosegear. Or in other words, a totally new aircraft, which really means there is no point in shrinking/redesigning a Y-7 in the first place because there would be absolutely nothing left of the original Y-7 anyway. What the H-600 looks like is an E-2 or Yak-44, not a shrunk down/Frankensteined Y-7. They bear no resemblance to each other except for the fact that they both have a fuselage and two wings.

    Hmm, let's see. Narrow, unblended fuselage? Check. High-mounted, high aspect ratio, unswept wings? Check. Multiple small, stubby vertical stabilizers? Check. Turbofan engines and MAYBE a fuselage bulge for landing gear? The only difference. Please detail for me how this would be a "very different" aircraft in "configuration and aerodynamics" to the E-2/Yak-44/H-600.
     
  7. Bltizo
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    Bltizo Lieutenant General

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    (The CGIs we've had of) H-600 looks a lot like JZY-01 to me..


    FYI I was talking about this part: "Swing wing fighters are perfect examples, being turbofan-driven aircraft yet with highly unswept modes for maximum lift and fuel efficiency, and highly swept modes for high speed dashes, which an AEW/C aircraft will never experience. As for the landing gear differences, they really wouldn't amount to much at all. If you are claiming that the landing gear would be located in the fuselage for a turbofan AEW/C instead of underneath the turboprop housing, maybe, maybe not. Even if they were located in the fuselage you would still see the same wide, thin, high aspect ratio wing, the same thin fuselage with maybe a bulge at the bottom rear for the landing gear (or not even), and the same multiple stubby aft vertical stabilizers which are an inevitable consequence of the radar dish."

    Moving the landing gear from the turboprop nacelles to the fuselage is a rather significant structural change, and while you won't be seeing fighter aircraft type swept wings, I cannot recall any contemporary turbofan powered subsonic aircraft with wings that are like that of the E-2. For example the sweep of turbofan powered aircraft like S-3 up to aircraft like C-17 are different to what we see on aircraft like E-2 or C-130.

    Take all of that and I see a different aircraft, and what I described above were very conservative minimal changes to the H-600 airframe anyway.
     
  8. Iron Man
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    Iron Man Captain
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    In as much as both have the type characteristics of a carrier-borne AEW/C aircraft, i.e. the radome, vertical stabilizers. And we have no idea if any of the details I mentioned specific to carrier flight ops were even a part of the JZY-01 airframe. If the JZY-01 is based on the Y-7 it is definitely a larger plane than the H-600. A smaller AEW/C airframe isn't a simple matter of somehow "shrinking down" a larger plane. I'm sure you understand this obvious point. If not, perhaps you could provide an example where something like this was actually done.

    Why are you talking about "moving"? There is no moving involved at all. Again, you DON'T have the blueprints of either the American or the Russian AEW/C plane (unless you want to start getting conspiratorial on me), so you are not "moving" anything around, whether the landing gear or anything else. All the PLAN has of the two planes are internet photos. A turbofan-driven H-600 would be a clean-sheet design. There is no risk-reduction going on because it's all new and all equally risky. And you trying to make a mountain of a molehill with the landing gear doesn't make it a "rather significant structural change" because 1) there is no change, and 2) a bulge at the bottom part of the rear of the fuselage has minimal effects on aerodynamics. You also haven't even established this plane would require a landing gear bulge in the first place, or that landing gear would have to be shifted to the fuselage at all.

    Don't worry, I can. Of the top of my head, the U-2 and the A-10 both have unswept high-aspect ratio wings. Both are turbofan-driven, and unsurprisingly, both are designed for low-medium speed, high endurance missions. Older fighters like the IL-28/H-5. I'm sure there are more.
     
    #108 Iron Man, Apr 5, 2019
    Last edited: Apr 5, 2019
  9. Bltizo
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    Bltizo Lieutenant General

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    Again, I refer to the phrase I used originally -- "substantially modify". Obviously it doesn't refer to merely "shrinking down" a larger plane.


    1. No change as in you're thinking of leaving the landing gear in the 2 turbofan engine nacelles in the same way as E-2/H-600/Yak-44? Or in the wings?
    2. considering the diameter of the fuselage of H-600, moving the landing gear from the engine nacelles to the fuselage under carriage almost certainly would change the cross section of the fuselage at that location rather dramatically.

    I think the onus here is on you to demonstrate that a turbofan powered variant of H-600 could allow the landing gear to retain the current position.



    And how many of those are derived from turboprop driven aircraft originally? If you really want to go back of course there are older 1st gen fighters like F-80 that are jet powered and with unswept, straight wings.

    Furthermore, when we consider contemporary turbofan powered aircraft intended for long endurance such as AEW&C and air to ground surveillance have swept wings (e.g.: P-8, E-7, and various business jets with military derivatives).
    Even turbofan powered aircraft designed for carriers intended for long endurance missions like S-3 and EA-6B have swept wings as well.


    Lastly, there are few if any direct "conversions" of turboprop driven aircraft to become turbofan or jet powered aircraft without very substantial modifications causing it in effect to become an entirely new aircraft.

    If you're suggesting that H-600 can be converted into a turbofan powered airframe with minor modifications then I think the onus is on you to demonstrate some evidence supporting the principle
     
  10. TerraN_EmpirE
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    TerraN_EmpirE Tyrant King

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    Neither never progressed beyond paper and models. Both were canceled leaving only the Kuznetsov and Helicopters. The Kuz then ended up in Ukraine as Russian boarders shrank. The Russians recovered her but the sister ship was left until it was bought and towed to China.
    Developed for the Common Support Aircraft requirement. Lock-Matt was proceeding along an established path to meet a desired product to replace S3,E2,C2,ES2. That program however was axed. https://fas.org/man/dod-101/sys/ac/csa.htm
    This left the Navy with the E2 and no other options. Part if of its mission was absorbed by the CMV22 and perhaps the MU(X) program will take up what is left.
     
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