Shenyang / Chengdu "6th Gen" Aircraft - News and Analysis

paralay said:
Three engines are a "crutch" for supersonic cruising speed. It will definitely have two engines when they are ready
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I am not interested in your wishful thinking being displayed here as fact as if those three engines were to be WS-15 then total output with afterburners could be 55 tons with dry thrust at 34 or 35 ton force. This is far more thrust than your two of your speculative engines that you believe for J-36 to must have and do not forget about your analysis/estimate of J-36 being powered by RD-33 sized engines that have output of WS-21 which no variant of RD-33 is capable of such output of 9.5 ton force. While there is WS-19 based on WS-15 that by some estimates and projections could have 12 ton force output thus 36 ton force with 3 engines. Problem with your narrative is that for such speculative engines you want J-36 to have would mean larger diameter and longer length thus require entire redesign of airframe.

EDIT:
Maybe redo your analysis with an high end estimate of J-36 being 26 meter long and wide as yours is lowest one.
 
Boxer (writing yesterday, J-36 very unconfirmed) itself looks very analogous to the first J-20: not quite a pre-production aircraft in every detail, but a full-size prototype rather than a minimal technology demonstrator, to be followed by a low-rate production batch. This process worked well on the J-20 and on the aircraft based on Shenyang’s FC-31.

There was also a lot of "only a tech demo" speculation when the J-20 appeared, and it was dead wrong. It may have originated with people not wanting to admit that Bob Gates had been wrong in 2009:

China, by contrast, is projected to have no fifth generation aircraft by 2020. And by 2025, the gap only widens. The U.S. will have approximately 1,700 of the most advanced fifth generation fighters versus a handful of comparable aircraft for the Chinese.
 
paralay said:
Two engines - two problems
Three engines - three problems
The required range cannot be achieved with three engines. Have you ever wondered why modern passenger planes have only two engines?
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If the engines have the same T/W ratio and the same SFC then how is it impossible to achieve the same range?

I get the logistics argument - but this other statement doesn't make sense.
 
paralay said:
Two engines - two problems
Three engines - three problems
The required range cannot be achieved with three engines. Have you ever wondered why modern passenger planes have only two engines?
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Engines are also heavy, and the third being present certainly eats into the performance more than having 2 engines that were designed for the job (as the current ones are definitely not).
 
paralay said:
Two engines - two problems
Three engines - three problems
The required range cannot be achieved with three engines. Have you ever wondered why modern passenger planes have only two engines?
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They have two because it is plausible since technology progressed that huge high bypass turbofan engines can be used yet that is very much different from fighter aircraft that has engines internally inside fuselage with long intakes while airliners have hanging under wing.

Your estimate of J-36 is at bottom of low end and most pessimistic to point it is not even realistic from what is available considering that Chinese WS-10 and soon WS-15 are all engines of comparable size to Russian AL-31 and AL-41 and AL-51 engines. All modern Chinese fighter jet aircraft use WS-10 series J-10, J-11, J-15, J-16 and J-20 while only J-35 is using WS-21(RD-33 size engine). For that very reason it does not make sense to ever consider truly as definitive that J-36 would use RD-33 sized engine be it WS-21 or WS-15 derived WS-19.

J-35 is the deviant as it uses WS-21 and soon WS-19 while only other Chinese aircraft is made with Pakistan that may soon use it is JF-17.

For whole premise is illogical in consideration of these facts of what engines Chinese primarily use, RD-33 analogue is not such primary.
Even if you were to remove middle engine and DSI intake on top of J-36. Larger engines will not work with J-36 if same intakes kept.
You would need to redesign whole aircraft to point of discarding majority of work done with J-36 that has been done by now.
 
Ainen said:
Kinda big and expensive for a test article, obvious sensor windows and IWBs.
Also, its flight was used as a political declaration. You don't declare things with flying an X-29 on Mao's birthday before Trump's innaguration.
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Yes, the Chinese tend to be very intentional about how/when/why they release things. Big emphasis on symbolism as well.
 
LowObservable said:
Boxer (writing yesterday, J-36 very unconfirmed) itself looks very analogous to the first J-20: not quite a pre-production aircraft in every detail, but a full-size prototype rather than a minimal technology demonstrator, to be followed by a low-rate production batch. This process worked well on the J-20 and on the aircraft based on Shenyang’s FC-31.

There was also a lot of "only a tech demo" speculation when the J-20 appeared, and it was dead wrong. It may have originated with people not wanting to admit that Bob Gates had been wrong in 2009:

China, by contrast, is projected to have no fifth generation aircraft by 2020. And by 2025, the gap only widens. The U.S. will have approximately 1,700 of the most advanced fifth generation fighters versus a handful of comparable aircraft for the Chinese.
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I'll just quietly again boost the idea that the Chinese language grapevine talking about J-20 when it emerged 14 years ago (and in the years of discussion leading up to its emergence, when it was known as J-XX) was basically roundly correct in all of their projections of J-20, if anything a few aspects ended up lowballing it (such as eventual procurement scale).

And FWIW, the consensus for J-36 is it is primarily an air to air combat aircraft, with long range, capable speed, relatively capable internal weapons load (compared to existing 5th gens), pursuit of significant signature reduction, and most importantly meant to operate within and to command and force multiply a system of systems warfighting approach including but not limited to UCAVs/CCAs.


Time will tell if this is correct, but 14 years ago people didn't listen to the PLA watching side of things when J-20 emerged (not directed to you, more in general among the online milspace) -- it may be worth keeping a more open mind this time.
 
Blitzo said:
And FWIW, the consensus for J-36 is it is primarily an air to air combat aircraft
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The confusion may relate to how the reader interprets "air to air combat". If we do assume an air to air mission, then "J-36" would seem to be more akin to a heavy interceptor (MiG-31) than an air superiority fighter (F-15). Some people see "air to air combat" and all they can think of is a turning WVR fight, something an F-22 or Su-57 would be far more suitable for. Then you get thought processes along the lines of "oh well if it isn't comparable to a Raptor it has to be a strike aircraft". A long-range, heavily-loaded interceptor, able to penetrate into an air defense network and unleash VLRAAMs at ISR and support assets? Very useful thing in a Pacific scenario.
 
Question for those in the know: Does the sweep angle of the intake lips tell anything about supersonic performance?
Compared to say the F-22 or the Su-57, the Chinese design has a more modest angled intake.
 
SOC said:
The confusion may relate to how the reader interprets "air to air combat". If we do assume an air to air mission, then "J-36" would seem to be more akin to a heavy interceptor (MiG-31) than an air superiority fighter (F-15). Some people see "air to air combat" and all they can think of is a turning WVR fight, something an F-22 or Su-57 would be far more suitable for. Then you get thought processes along the lines of "oh well if it isn't comparable to a Raptor it has to be a strike aircraft". A long-range, heavily-loaded interceptor, able to penetrate into an air defense network and unleash VLRAAMs at ISR and support assets? Very useful thing in a Pacific scenario.
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I agree, that is a major area of confusion.

I also think that many people who have correctly laid out the importance of CCAs/UCAVs for USAF future air combat concepts, aren't applying the same rationale to the PLA or this J-36 aircraft.
I.e.: the ability to loiter, operate at range in a stealthy manner and collate, process and command large supporting elements of CCAs/UCAVs will be an essential part of forthcoming "air superiority" capability as well.


I see this aircraft as a large, long range and endurance, stealthy, command+processing platform to direct friendly UCAVs and other manned fighters, while possessing its own very capable onboard weapons + sensors to engage targets independently when needed, and to possess enough kinematics to engage, disengage or avoid engagements on its own terms.
And I also view the above descriptor as what the future of an "air superiority aircraft" may be oriented towards.
 
eagle said:
Question for those in the know: Does the sweep angle of the intake lips tell anything about supersonic performance?
Compared to say the F-22 or the Su-57, the Chinese design has a more modest angled intake.
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Yes, it does! As mentioned earlier, in a caret intake the first oblique shock essentially covers the inlet aperture like a lid at design speed. The sharper the sweep angle, the higher the design speed, since a steep shock at high Mach number causes high total pressure loss.

That's why in my opinion talk of TBCC engines or extremely high speed is implausible in relation to this aircraft.
 
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The caret inlets on the F-22 and Su-57 are based on 2-dimensional flow fields, and can be quasi-3-dimensional, particularly the F-22 which is swept more "symmetrically" along multiple axes. These inlets provide good pressure recovery at Mach 2+ speeds.

This does make the more modest sweep angles of the J-36 caret inlet a bit odd, but it's possible that the design aims for maximum supercruise efficiency at around Mach 1.5 rather than good Mach 2+ recovery for the more swept inlets. That said, one has to wonder why the J-36 even bothers with caret inlets at all if it’s not aiming for a high maximum afterburning speed. A DSI would offer acceptable pressure recovery while also being lighter and stealthier. Perhaps a DSI, while having better efficiency than a pitot inlet like the F-16’s, still doesn’t quite compare to the multi-shock system of a caret inlet.

That said, the inlet shaping could still change, as was the case with the J-20 prototypes and pre-production aircraft.
 
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icyplanetnhc (Steve) said:
That said, the inlet shaping could still change, as was the case with the J-20 prototypes and pre-production aircraft.
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Within the scope of edge alignment for stealth, there are some fairly heavy constraints though (the changes on the J-20 did not affect any relevant angles). I could maybe see them eliminate one or both BL diverter gaps if they can find a way to bleed away enough air via additional perforations.
 
Another factor to consider, if the J-36 inlet sweep angles are too shallow (i.e. too high deflection angle), can the shock at the edges even remain at a “weak” shock condition that’s more ideal for pressure recovery?
 
Blitzo said:
I agree, that is a major area of confusion.

I also think that many people who have correctly laid out the importance of CCAs/UCAVs for USAF future air combat concepts, aren't applying the same rationale to the PLA or this J-36 aircraft.
I.e.: the ability to loiter, operate at range in a stealthy manner and collate, process and command large supporting elements of CCAs/UCAVs will be an essential part of forthcoming "air superiority" capability as well.


I see this aircraft as a large, long range and endurance, stealthy, command+processing platform to direct friendly UCAVs and other manned fighters, while possessing its own very capable onboard weapons + sensors to engage targets independently when needed, and to possess enough kinematics to engage, disengage or avoid engagements on its own terms.
And I also view the above descriptor as what the future of an "air superiority aircraft" may be oriented towards.
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Sounds good. The mirror-imaging can be annoying. "J-20 is inferior because China can't build flat vectoring nozzles" rather than "looks as if they didn't think it was worth the weight".
 
paralay said:
Two engines - two problems
Three engines - three problems
The required range cannot be achieved with three engines. Have you ever wondered why modern passenger planes have only two engines?
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Because the desired ranges can be reached more cheaply with two than three (or four) and the authorities allow it. The switch to two engines was tightly tied to the improvements in reliability meaning the national airworthiness authorities were willing to accept ETOPs. Remember, Airbus's long range widebody design of choice was the four-engined A340 with its literal half-sibling the A330 for shorter range routes. ETOPs destroyed the A340 not because it couldn't meet the range requirements, but because twins could meet them more cheaply.

(A340-200, 15,000km range, A330-200, 13,500km range, A330-800 neo, 13,900km, difference in fuselage lengths between the three about a metre).
 
Elysium said:
This might just a dumb theorycraft, but what if instead of going the variable bypass route, they had 2 low bypass turbofans for takeoff/supercruise/manuevering conditions, and one high bypass one optimized for efficient subsonic cruise?
On takeoff/ low speed manuevering, they might be using all 3 simultaneously for maximum power.

Edit: If fww115's picture is the real thing, the middle engine seems to have a rather short intake combined with a sizeable hump, meaning it could indeed be housing a high-bypass turbofan.
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If that's the case, then that raises some major questions about the progress of their engine development. I would not expect them to be at the same level as the US, but surely they could scale up a pre-existing design and make it work rather than creating a highly complicated mess?

I'm still inclined to think that it's the JH-XX and not a sixth generation fighter, simply because you'd really be opening a can of worms with that top intake.

Either way, I cannot wait for the NGAD (and hopefully GCAP) spending boost.
 
LowObservable said:
Sounds good. The mirror-imaging can be annoying. "J-20 is inferior because China can't build flat vectoring nozzles" rather than "looks as if they didn't think it was worth the weight".
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I think sometimes there are cases of excess mirror imaging (why are XYZ choosing this alternative approach, it must be due to ABC limitation/weird doctrine) and some cases of insufficient mirror imaging (like not applying global CCA/UCAV trends to this new aircraft, or even back when the PL-17 emerged many didn't take it very seriously but then being quite content with AIM-174B).

Oh well, some things change, some things stay the same.
 
My instinctive reaction to the layout, whatever is going on with the engines, is that if you're designing purely for air combat, you'd really want better visibility than the cockpit seems to provide. Because however good your LRAAM and MRAAM capability, sometimes the merge is going to happen and it'll be a bugger if you're in a turning fight and you can't see behind and above.

We really need better pics of the cockpit area. That's assuming there is a cockpit...

There are potentially technological ameliorations, EOTS systems that let you look through the aircraft, but a bubble canopy is difficult to beat in terms of simplicity.

Yes, there have been air combat aircraft without bubble-canopies, but they tend to be interceptors or conversions - Tornado ADV, MiG-25, MiG-31, F-111B, YF-12....
 
Josh_TN said:
It seems to have bomb bays and nose mounted sensors. That seems like a lot for a TD, though perhaps those areas are mock ups just for intimidation. But would not so many operational looking features suggest more of a prototype?
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When I said technology demonstrator, I thinking more like YF-22 and YF-23. This particular airframe may be built toward a specific concept to help validate any high risk areas, then it progresses toward a final production design incorporating what worked well on the demonstrator.
 
DWG said:
My instinctive reaction to the layout, whatever is going on with the engines, is that if you're designing purely for air combat, you'd really want better visibility than the cockpit seems to provide. Because however good your LRAAM and MRAAM capability, sometimes the merge is going to happen and it'll be a bugger if you're in a turning fight and you can't see behind and above.

We really need better pics of the cockpit area. That's assuming there is a cockpit...

There are potentially technological ameliorations, EOTS systems that let you look through the aircraft, but a bubble canopy is difficult to beat in terms of simplicity.

Yes, there have been air combat aircraft without bubble-canopies, but they tend to be in the
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It depends on how you are approaching air-combat. If you are primarily relying on BVR jousting (and trying to get the first shot off) - your 'close range' might be 50 km or 70 km... ranges where sustained cruise and supersonic turn circles matter more.

That might make sense for a design with a very powerful radar (say, powered by a third engine), VLO (tailless diamond design), super cruise, and VLRAAM missiles...

It is quite possible that the J-20 pilots would end-up using the Mk.1 Eyeball... but this new aircraft might only experience BVR (and could use a degree of sensor fusion if it was ever forced by circumstances into WVR).

Part of me is with you - give me analogue dials as a back-up, maybe a gun in case the missiles run out - but I suspect that we're moving beyond that - and this design could probably coordinate with other assets to make sure it keeps its distance.
 
Thinking about three engines, that really gives you some interesting loiter abilities - one engine, two engines, or all three. Though I quite like Sweetman's idea of a different central engine to give you a poor-man's variable cycle engine with current technology.
 
Avimimus said:
It depends on how you are approaching air-combat. If you are primarily relying on BVR jousting (and trying to get the first shot off) - your 'close range' might be 50 km or 70 km... ranges where sustained cruise and supersonic turn circles matter more.

That might make sense for a design with a very powerful radar (say, powered by a third engine), VLO (tailless diamond design), super cruise, and VLRAAM missiles...

It is quite possible that the J-20 pilots would end-up using the Mk.1 Eyeball... but this new aircraft might only experience BVR (and could use a degree of sensor fusion if it was ever forced by circumstances into WVR).

Part of me is with you - give me analogue dials as a back-up, maybe a gun in case the missiles run out - but I suspect that we're moving beyond that - and this design could probably coordinate with other assets to make sure it keeps its distance.
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It's also not just BVR -- it's being screened by formations of sensor and weapons equipped CCAs/UCAVs that you control and are networked with positioned in intervals up to hundreds km ahead of you, in concert with existing/upgraded 5th generation aircraft, then something has probably gone a bit wrong if an enemy has been able to get through all of that and come within merge distance of yourself, without you in the aircraft being able to evade or choose a vector that denies engagement.


===

If you're having to turn your head back because an opfor managed to get literally behind you were a Mk1 eyeball through the canopy is essential, then you probably deserve to get shot down by that point.
Alternatively, if you do want "visual 360 awareness" it is likely that AR helmets and further iterations of what EODAS can provide, will assist in that.
 
Avimimus said:
It depends on how you are approaching air-combat. If you are primarily relying on BVR jousting (and trying to get the first shot off) - your 'close range' might be 50 km or 70 km... ranges where sustained cruise and supersonic turn circles matter more.
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That was the gameplan for Typhoon*, and yet it still featured a bubble-canopy and good dogfighting capability. The two concepts aren't mutually exclusive, which makes me wonder "Why?".

* And presumably is for GCAP.
 
DWG said:
Thinking about three engines, that really gives you some interesting loiter abilities - one engine, two engines, or all three. Though I quite like Sweetman's idea of a different central engine to give you a poor-man's variable cycle engine with current technology.
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I thought of that idea. But if you used the internal volume taken up by the intake and high bypass engine and used it for fuel then it might be wash in terms of performance. You also eliminate the cost and complexity of the third engine.
 
Blitzo said:
something has probably gone a bit wrong
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That's why we design for things going a bit wrong - the other guy's designers are designing their platforms to make things go wrong for you.

if an enemy has been able to get through all of that and come within merge distance of yourself, without you in the aircraft being able to evade or choose a vector that denies engagement.
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Your job in an air combat platform isn't to evade, it's to stop the other guy completing his mission. If you are the last air combat asset between the bad guy and a high value asset, you engage, even if all you have left as SRAAMs, or even the gun. Or even just the aircraft itself, cf 9/11.

So good rearward visibility is a valuable asset, whatever you plan to do in the optimal situation, and a design that doesn't optimise for that is optimising for something else, and the choices tell us something about the assumptions behind the design.
 
DWG said:
Thinking about three engines, that really gives you some interesting loiter abilities - one engine, two engines, or all three. Though I quite like Sweetman's idea of a different central engine to give you a poor-man's variable cycle engine with current technology.
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No need to attribute this to B.S. We can and have made similar hypothesis here priorly.

Regarding the black canopy, recently PLAN had emphasized heavily in the online press the usage of blinding laser with not an ounce of shame. Seems that would explain the extreme tint of their glazing.
 
DWG said:
That's why we design for things going a bit wrong - the other guy's designers are designing their platforms to make things go wrong for you.
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That is correct, however the other guy's designers are also constrained and enabled by similar technologies and physics as you are.
Your job is to locate and identify the likely ways in which the other guy will try to make things go wrong for you, and to try to compete in the highest yield/threat ones.

The idea of next generation air superiority fighters emphasizing their design for WVR merges may become something like "what if the enemy fighter lands at your airbase and uses their gun to shoot you while you're spooling up" -- a technically feasible situation to encounter, but also very unlikely to occur. You'll have to design your aircraft around the highest risk and most likely scenarios in which the other guy may try to outcompete with you.



DWG said:
Your job in an air combat platform isn't to evade, it's to stop the other guy completing his mission. If you are the last air combat asset between the bad guy and a high value asset, you engage, even if all you have left as SRAAMs, or even the gun. Or even just the aircraft itself, cf 9/11.
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Actually, your job as an air combat platform is to complete your mission (which may or may not involve denying the other guy from completing their mission).

If you are the last aircraft standing between the enemy and a high value target that must be defended as part of your mission, then absolutely you'll be pushing your aircraft with everything you have.
If an enemy has somehow managed to approach you and you have supporting elements within range to intercept them more efficiently while allowing yourself to remain safe, then the natural response is to tactically withdraw and let your plentiful supporting CCAs/UCAVs and friendly 5th gens to tangle with the enemy and to also give yourself the ability to position for a better shot.


DWG said:
So good rearward visibility is a valuable asset, whatever you plan to do in the optimal situation, and a design that doesn't optimise for that is optimising for something else, and the choices tell us something about the assumptions behind the design.
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Rearward visibility is a valuable asset yes, but among the hierarchy of useful and important modern air superiority traits it is near the least valuable on the totem pole. That is especially the case with further maturation of helmet mounted AR systems paired with 360 degree EO/IR passive sensors.

For the 2030s, with things playing out the way they seem to be, if I were choosing traits of an air superiority fighter I'd prefer to put points into higher yield domains like signature reduction, networking, sensors, processing, endurance/range, weapons, power generation, meanwhile a sufficient minimum in kinematic maneuverability and cockpit eyeball visibility is fine but does not require anything bleeding edge.
 
Blitzo said:
The idea of next generation air superiority fighters emphasizing their design for WVR merges may become something like "what if the enemy fighter lands at your airbase and uses their gun to shoot you while you're spooling up"
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And yet people keep putting dedicated SRAAM bays in their designs. And even when people have a valid case for 'Is that really necessary', there's considerable institutional inertia around retaining capabilities - cf the RAF, Typhoon, and the internal gun.

if I were choosing traits of an air superiority fighter I'd prefer to put points into
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But with a free hand you'd also want good external vision without a technological dependency. If you opt not to include that, it tells us things. The interesting point isn't 'they could do that', but 'why did they do that?'.
 
snne said:
Here's a nice counter argument for you guys:

https://twitter.com/x/status/1872535461945577902
View: https://x.com/Tas1Bora/status/1872535461945577902?s=19
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heavier the aircraft, the G load forces grow too

At 9Gs at 70 Kilogram pilot will weight 630 kg
a 55000 kg aircraft at 9G will weight close to 500,000kg the structure will not resist, simple like that.

Paralay is using real life examples since Su-34 and MiG-31 are heavy and have lower G load capability than the lighter Su-27 or MiG-29.

Sr-71 also was very limited due to heavy weight.

This machine is an attack aircraft with some air to air capability at long range.

Basically a modern Su-34.

If you do not believe it check the overload Limit of Tu-22M, B-1B, Su-34, F-111, MiG-31.

Heavy aircraft are built with the same materials and basic structures that lighter aircraft are built with to some degree.

Having 3 engines means lots of fuel.

The landing gear shows a very heavy weight aircraft.

I weigh approximately 200 pounds, 230 with my gear on. For most people, the peak G-force they’ve experienced is probably on a rollercoaster during a loop—which is about 3-4G’s. It’s enough to push your head down and pin your arms by your side. Modern fighters like the F-16 and F-35 pull 9G’s, which translates to over 2,000 pounds on my body.
www.wearethemighty.com

G-Forces and Fighter Pilots: What’s it like to pull 9Gs?

G-forces don't translate to the big screen, or to video games, but they are a major aspect of flying fighters. Movies like Top Gun show the characters
www.wearethemighty.com www.wearethemighty.com

Now consider the same happens to the structure
 
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Jason Dykstra (Wyvern) said:
If that's the case, then that raises some major questions about the progress of their engine development. I would not expect them to be at the same level as the US, but surely they could scale up a pre-existing design and make it work rather than creating a highly complicated mess?

I'm still inclined to think that it's the JH-XX and not a sixth generation fighter, simply because you'd really be opening a can of worms with that top intake.

Either way, I cannot wait for the NGAD (and hopefully GCAP) spending boost.
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I agree because the Chinese were always behind in jet engine design and manufacturing.
 
LowObservable said:
Sounds good. The mirror-imaging can be annoying. "J-20 is inferior because China can't build flat vectoring nozzles" rather than "looks as if they didn't think it was worth the weight".
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Agree. Would recommend the fanalysis start with "what would the requirements and missions be for this class airframe?" followed by "how were they met?".
 

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