PLA next/6th generation fighter thread

[sunnymaxi]

I won't touch upon the validity or veracity of a triple-engine-equipped next-gen warplane (not just fighter aircraft), given how scarce the reliable information which we have access to at the present moment.

Let the bullets fly for a while (让子弹飞一会儿).

---

Recall that famed Academician Liu Daxiang (刘大响工程院院士) of the Chinese Academy of Engineering said this during the 2022 Keynote Report of China Aviation Industry Conference in late-November 2022, other than J-20A's WS-15 (directly translated):


View attachment 140245

While I do agree that China's mastery in engine technology is still some distance away from the international leading standards (i.e. the US), I don't believe that China is absolutely that far behind them in this field at this stage of progress. We're in 2024 and not 2004, after all.

Going back to the presentation from December 2022, I have sufficient reasons to believe that the "5th-gen low-bypass turbofan engine" mentioned by Academician Liu is actually referring to the VCE/ACE meant to power China's next-generation J-XD.

Beyond the aforementioned TWR of 12-15 (which is a huge step-up from the current 4th-gen LBP turbofan engines' TWR of ~10) - What are the key performance parameters that we can expect from such engines?

Weight of the engine? Military (dry) thrust? Maximum (augmented) thrust? Turbine inlet temperature? Etc. I think these could be more useful for discussion/argument WRT powerplants for the J-XD.

He is the highest authority in mainland China when it comes to turbofan engine industry. the fact is, he was also the biggest critics of AVIC engine policy.

during the Conference in 2022, he literally said, China will be the Tier1 player in Aero engine industry by 2035.

based on his statement regarding ''next generation engine technologies successfully breakthrough the barrier'' back in 2022 and during 2024 airshow we have seen Engine components with 3D printed additive manufacturing. AECC Chengdu/AECC Sichuan and NPU Xian have completed the process of next generation Engine components manufacturing facilities. which will be based on additive techniques and next gen laser 3D printed.

if i m not wrong. so far only GE have used additive manufacturing in commercial turbofan Engines. this shows what AECC is thinking about China's military turbofan Engines.

 

[tphuang]

When j-20 first came out, people were shocked at its size and thought it was a fighter bomber which persisted long after. And now it seems quite prescient that they made it so large.

now we all think j-xd will be larger. My assumption was something along the line of 20% heavier than j-20 to make use of the higher thrust they will get. (Ws-15 vs ws-10c).

now if plaaf actually believes J-XD needs to be 60 to 70% larger (as in MTOW) vs J-20, then clearly just the generational upgrade in engine isn’t enough.

What if plaaf requirement for J-XD is 4000 km range instead of 2000 km? What if loyalwing man are going to be J-10 size in MTOW?

I think whatever we see from this aircraft will provide us more info of how PLA envisions future air warfare to be rather than any tech limitations. Plaaf was entirely okay with testing and fielding first j-20s with underpowered AL31. So I just don’t see how underpowered engine is a concern here.

 

[Blitzo]

That implies the Chinese aeroengine industry is in a much worse place than even the most conservative estimates. No one here would argue they're the best in the world, but they're certainly not that far behind that they'd cripple the 6th gen design with something like a third engine, especially given how fast China is advancing. The much better play would be to wait for the engines to advance and mature, especially since NGAD is delayed/soft cancelled.

They were in a far worse place both in relative and absolute terms with the J-20 and they didn't cripple that design to accommodate weak engines. They just bit the bullet and flew the airframe they wanted in a nerfed configuration, and that's what we should overwhelmingly expect here.

Lol yes, I agree that I would have expected them to have bitten the bullet and pursued the aircraft in a nerfed fashion.

If they chose three engines, then yes the bolded part is more or less what I'm saying in terms of "implications for aeroengine industry" -- at least for their ability to develop a next generation engine (whether it's a high thrust VCE or otherwise) on a timescale that would work for J-XD. (To be fair it doesn't necessarily mean the Chinese aeroengine industry is in a much worse place than even the most conservative estimates -- it may just be that the advance to VCEs is much more difficult than we in the public estimated)

I'll rephrase what Index said because I think the idea is correct: If the 6th gen design indeed has three engines, then that's an inherent feature of CAC's conception of a 6th generation fighter. It would have 3 engines even if China had the American engine industry.

I'm not going to exclude that possibility, but imo that would require the PRC aeroengine industry to have demonstrated a record or have credible rumours of it being sufficiently advanced, in a manner that would lend us to believe that they can produce engines of sufficient sophistication and thrust for the life cycle of J-XD.

Like, if next hear we start seeing 100x J-20s produced with WS-15s and we see multiple flying prototypes of J-20 or even J-XD powered by a high thrust VCE, then yeah sure I'd be quite comfortable agreeing that a three engine configuration is a reflection of greater ambition and that they are technologically, pound for pound not inferior.

How have we not? Is the WS-15 not a thing?

See above.

====

No other country besides US has put 2 10 TwR range fighter jet engines into service. So China experiences an equal degree of technological "backwardsness" as US and less than anyone else.

The leader is the trend setter, I.e. Whoever puts out the first 6th gen. If US puts out a 6th gen first, it has 2 engines and has the same rough capability as 3 engined J-XD, then a credible discussion about limitations can be made. But this is far from what's happening.

The natural assumption when an industry leader tries a new thing is that it is done because it is the next generation step, unless indicated otherwise. China isn't UK or Turkey, it doesn't experience the need to compromise on designs, as evidenced by J-20, J-35 etc.

If the Chinese aeroengine industry was an "industry leader" then I would agree with you.

As for "compromising" on designs -- on the contrary, I would argue J-20 and J-35/A were compromised in terms of powerplant.
J-20 used Al-31s and WS-10s for years and may soon finally enter production with WS-15s, and J-35/A with WS-13E and WS-21 (and even FC-31 RD-93/33) which supposedly may have flown recently with WS-19s.

But let's be honest if the PRC aeroengine industry was truly an industry leader, then J-20 s/n 2001 would've flown with WS-15s back in 2010, and FC-31V1 would've flown with WS-19s back in 2012. To their credit, they never let engine technology take themselves hostage, a wise decision, but it doesn't take away from the fact that up to this point, their new fighter aircraft have been out of sync with their somewhat more backwards engine development.

There has never been a PRC equivalent of "YF-22 or YF-23 flying with YF119/YF120" for example, or even "F-35A prototype AA-1 flies with F135".


Until such the point that the PRC is considered an "industry leader" in aeroengines, I would agree that the null hypothesis could be that a hypothetical decision for a hypothetical 3 engine design, is not due to technological/engine industry reasons. Until then, the null hypothesis should be that the choice was done due to individual engine technology/capability reasons.

Of course, if J-XD flies in the next couple of months and it has three engines, and if credible rumours suggest it is powered by high thrust VCEs that will be its intended engines, and those intended engines in turn do not seem inferior to say NGAP that the US is pursuing... then I'd be quite content changing my position in context of new information.

 

[Index]

Lol yes, I agree that I would have expected them to have bitten the bullet and pursued the aircraft in a nerfed fashion.

If they chose three engines, then yes the bolded part is more or less what I'm saying in terms of "implications for aeroengine industry" -- at least for their ability to develop a next generation engine (whether it's a high thrust VCE or otherwise) on a timescale that would work for J-XD. (To be fair it doesn't necessarily mean the Chinese aeroengine industry is in a much worse place than even the most conservative estimates -- it may just be that the advance to VCEs is much more difficult than we in the public estimated)




I'm not going to exclude that possibility, but imo that would require the PRC aeroengine industry to have demonstrated a record or have credible rumours of it being sufficiently advanced, in a manner that would lend us to believe that they can produce engines of sufficient sophistication and thrust for the life cycle of J-XD.

Like, if next hear we start seeing 100x J-20s produced with WS-15s and we see multiple flying prototypes of J-20 or even J-XD powered by a high thrust VCE, then yeah sure I'd be quite comfortable agreeing that a three engine configuration is a reflection of greater ambition and that they are technologically, pound for pound not inferior.




See above.

====



If the Chinese aeroengine industry was an "industry leader" then I would agree with you.

As for "compromising" on designs -- on the contrary, I would argue J-20 and J-35/A were compromised in terms of powerplant.
J-20 used Al-31s and WS-10s for years and may soon finally enter production with WS-15s, and J-35/A with WS-13E and WS-21 (and even FC-31 RD-93/33) which supposedly may have flown recently with WS-19s.

But let's be honest if the PRC aeroengine industry was truly an industry leader, then J-20 s/n 2001 would've flown with WS-15s back in 2010, and FC-31V1 would've flown with WS-19s back in 2012. To their credit, they never let engine technology take themselves hostage, a wise decision, but it doesn't take away from the fact that up to this point, their new fighter aircraft have been out of sync with their somewhat more backwards engine development.

There has never been a PRC equivalent of "YF-22 or YF-23 flying with YF119/YF120" for example, or even "F-35A prototype AA-1 flies with F135".


Until such the point that the PRC is considered an "industry leader" in aeroengines, I would agree that the null hypothesis could be that a hypothetical decision for a hypothetical 3 engine design, is not due to technological/engine industry reasons. Until then, the null hypothesis should be that the choice was done due to individual engine technology/capability reasons.

Of course, if J-XD flies in the next couple of months and it has three engines, and if credible rumours suggest it is powered by high thrust VCEs that will be its intended engines, and those intended engines in turn do not seem inferior to say NGAP that the US is pursuing... then I'd be quite content changing my position in context of new information.

High trust VCE for NGAD is however just vaporware.

Until US or someone else proves there is a new, higher standard than WS-15/F135, all that above is simply highly speculative.

China is an industry leader based on what we know of 2024s engine tech. We can't extrapolate 2030s potential US engine tech and then use that to compare with 2024s China engine tech to conclude US is "ahead", that makes no sense at all and is just dumb nationalist cope from Americans.

I'd be inclined to consider your hypothesis only when US puts their own NGAD in service, it has 2 engines and can achieve the same capability as J-XD if J-XD indeed has 3 engines.

 

[Blitzo]

I think whatever we see from this aircraft will provide us more info of how PLA envisions future air warfare to be rather than any tech limitations. Plaaf was entirely okay with testing and fielding first j-20s with underpowered AL31. So I just don’t see how underpowered engine is a concern here.

I don't think anyone is particularly concerned about the idea of J-XD using underpowered engines.

The question is more about the idea of J-XD using three underpowered engines rather than two underpowered engines.

Two underpowered engines would signal rather obviously that the intent is for them to be replaced by higher power target engines, that are able to meet the needs of the airframe.
But using three underpowered engines, implies that the aircraft's structure, internal bulkheads and ducting, mass, will not be changed for future iterations of the aircraft that use the eventual higher power target engines... and no one uses three engines out of choice -- i.e.: the aircraft needs three target engines.

Thus the question becomes: for a hypothetical J-XD configuration of three engines, are they choosing three target engines because the aircraft's characteristics itself requires three engines and each target engine is technologically similar and capable to equivalents by other global leaders -- or is it that the engines are individually technologically less capable and lower thrust than global leaders thus needing three engines as a compromise where they would have preferred two engines?

IMO until the Chinese aeroengine demonstrates high level competency and technological catch-up, we are obliged to go with the latter.


Keeping in mind of course, this is all just a hypothetical discussion on the idea of J-XD being a three engine configuration spurred on by that speculative art a few days ago. I personally do not have a major opinion as to whether J-XD will actually be three engine or not (I tend slightly in the negative to be honest).

High trust VCE for NGAD is however just vaporware.

Until US or someone else proves there is a new, higher standard than WS-15/F135, all that above is simply highly speculative.

China is an industry leader based on what we know of 2024s engine tech. We can't extrapolate 2030s potential US engine tech and then use that to compare with 2024s China engine tech to conclude US is "ahead", that makes no sense at all and is just dumb nationalist cope from Americans.

I'd be inclined to consider your hypothesis only when US puts their own NGAD in service, it has 2 engines and can achieve the same capability as J-XD if J-XD indeed has 3 engines.

That's a very bold set of assumptions to take when aeroengines are one of the remaining domains of the aerospace industry where the US retains a large and significant lead (albeit seemingly shrinking, in recent years), on the PRC.

To me, the more natural position is that it's up to the PRC to prove itself and to demonstrate its technological non-inferiority, rather than to cast skepticism towards US next generation efforts. But if that's really what you believe then I have nothing else to say, because this set of assumptions we're operating off are so completely out of phase with each other that there's basically no middle ground.


Edit: just regarding the bolded part, I am not comparing what we know of 2024s engine tech in China. I am comparing what is known in 2024 of Chinese engine tech, with what is known of 2024 US engine tech, and also going off J-XD being a three engine design where a two engine design is always going to be preferable.
If J-XD was a two engine design, I would actually be more tended to hypothesize that their future target engine to be of similar capability and technology with global peers. However, as a three engine design, it is more prudent to assume that their future target engines are insufficient for them to adopt a two engine design for it, rather than believing that their future target engines will be technologically similar/equal to global peers and thus the J-XD having three engines would make it some kind of super large/capable fighter instead.

 

[Index]

That's a very bold set of assumptions to take when aeroengines are one of the remaining domains of the aerospace industry where the US retains a large and significant lead (albeit seemingly shrinking, in recent years), on the PRC.

To me, the more natural position is that it's up to the PRC to prove itself and to demonstrate its technological non-inferiority, rather than to cast skepticism towards US next generation efforts. But if that's really what you believe then I have nothing else to say, because this set of assumptions we're operating off are so completely out of phase with each other that there's basically no middle ground.

The natural position for both US and China is that they'll first have to prove they have a next gen capability before it can be conclusively stated if the other side needs to prove their "non inferiority". Isn't that the most normal null hypothesis?

So if US shows they have a 2 engined NGAD that can do what a hypothetical 3 engined J-XD can do, they have proven technological superiority. (Or vice versa if US is "forced" to make a 3 engined NGAD to match a 2 engined J-XD). If however the J-XD flies with capabilities that US has never flown with, then that is also an indicator that China is ahead, for the moment.

Seems madness to me to take 2 sides that are neck to neck and try to assign inherent assumptions on how platforms will turn out based on that. Nations steal a march on the other side all the time. Whether it's US that's 9.5 to China's 10 or vice versa, the chances for the next platform are a toss up.

We can only rely on demonstrated capability.

 

[Gloire_bb]

Until US or someone else proves there is a new, higher standard than WS-15/F135, all that above is simply highly speculative.

China is an industry leader based on what we know of 2024s engine tech.

Can we hold our horses a bit? Optimism is good, but F119 has first flown more than 3 decades ago, and is in service for 2.
F135 - two and one decade respectively.

Current China's level is WS-10c. Reliable enough, but still with relatively low service life. This is not leader, this is not catching up, there's a whole flock of earlier, similar and higher performing engines around the world.

That's not leader, that's mid-1990s production engine (core tech from 1980s) . I.e. this level of engine is like 40 years fresh.

Ws-15 has flown, but it isn't a production engine yet. Maybe next year, maybe the year after.

Same on ws-19 - excellent, but not yet. Same on ws-20 (first Chinese high bypass turbofan) - excellent, but not yet.
And now everyone is surprised that variable engine doesn't fly ahead of US. Like, we should be reasonable.

When China will become a leader - it will.
It's the single most difficult industrial catch-up of our time, not easy walk.
For now, especially if the goal is to get 50t fighter with fighter thrust to weight ratio(and additional power generation) - Chengdu has to either add an engine, or cut T:W, or produce a smaller bird in same class as J-20.
There's no magic.

 

[Index]

Can we hold our horses a bit? Optimism is good, but F119 has first flown more than 3 decades ago, and is in service for 2.
F135 - two and one decade respectively.

Current China's level is WS-10c. Reliable enough, but still with relatively low service life. This is not leader, this is not catching up, there's a whole flock of earlier, similar and higher performing engines around the world.

That's not leader, that's mid-1990s production engine (core tech from 1980s) . I.e. this level of engine is like 40 years fresh.

Ws-15 has flown, but it isn't a production engine yet. Maybe next year, maybe the year after.

Same on ws-19 - excellent, but not yet. Same on ws-20 (first Chinese high bypass turbofan) - excellent, but not yet.
And now everyone is surprised that variable engine doesn't fly ahead of US. Like, we should be reasonable.

When China will become a leader - it will.
It's the single most difficult industrial catch-up of our time, not easy walk.
For now, especially if the goal is to get 50t fighter with fighter thrust to weight ratio(and additional power generation) - Chengdu has to either add an engine, or cut T:W, or produce a smaller bird in same class as J-20.
There's no magic.

Yes, as what I'm saying, let's hold our horses until US proves it can do what China supposedly can't: 2 engined NGAD the size of J-XD with non inferior capabilities (assuming J-XD even drops with 3 engines at all).

US has had F-22 for a long time yes. That doesn't liberate them from the need to prove they have a future capability before it can be used in comparison. Time spent as a leader only means something when you show your progress.

 

[Blitzo]

The natural position for both US and China is that they'll first have to prove they have a next gen capability before it can be conclusively stated if the other side needs to prove their "non inferiority". Isn't that the most normal null hypothesis?

So if US shows they have a 2 engined NGAD that can do what a hypothetical 3 engined J-XD can do, they have proven technological superiority. (Or vice versa if US is "forced" to make a 3 engined NGAD to match a 2 engined J-XD). If however the J-XD flies with capabilities that US has never flown with, then that is also an indicator that China is ahead, for the moment.

Seems madness to me to take 2 sides that are neck to neck and try to assign inherent assumptions on how platforms will turn out based on that. Nations steal a march on the other side all the time. Whether it's US that's 9.5 to China's 10 or vice versa, the chances for the next platform are a toss up.

We can only rely on demonstrated capability.

Well, there is a possibility that the US manned NGAD may be rather different to J-XD even independent of the number of engines they respectively have -- considering the USAF's review of NGAD and their system of systems approach and their ability to finance the project, they may well be seeking to adopt a smaller manned NGAD platform than they previously envisioned, which would make the discussion about comparing J-XD and manned NGAD directly, somewhat superfluous because they would have very different concept of operations to begin with.


My view is that until the Chinese aeroengine industry proves itself to be at least equal to that of current global leaders (specifically the US), then any sort of question or comparison where the answer hinges on the matter of Chinese engines and the two options are roughly "optimistic view towards Chinese engine development" versus "pessimistic view towards Chinese engine development" -- then the obligator answer should be the latter, until there is reason to believe otherwise (at minimum, credible rumours, but ideally seeing progress in the flesh) on a case by case basis.



I'm not going to exclude the possibility that a hypothetical three engine J-XD might be pursued because of the aircraft's own requirements rather than engine technology/capability inferiority. But to do so would also force us to give the Chinese aeroengine industry more benefit of doubt than it currently deserves, without any current corroborating credible rumours to suggest that benefit of doubt is deserved in this specific hypothetical case anyhow.

 

[Blitzo]

Yes, as what I'm saying, let's hold our horses until US proves it can do what China supposedly can't: 2 engined NGAD the size of J-XD with non inferior capabilities (assuming J-XD even drops with 3 engines at all).

US has had F-22 for a long time yes. That doesn't liberate them from the need to prove they have a future capability before it can be used in comparison. Time spent as a leader only means something when you show your progress.

No, holding the horses should not be done to expect the US to prove itself.
Instead, should be holding our horses to see whether China can prove itself (the point of his post was to demonstrate that China is still significantly behind the US in aeroengines, and that China is very much not a global leader).


The natural, obligatory response to the idea of a J-XD having three engines should be one of assuming that it is due to engine deficiencies, until there is a reason to suspect otherwise.

Can we hold our horses a bit? Optimism is good, but F119 has first flown more than 3 decades ago, and is in service for 2.
F135 - two and one decade respectively.

Current China's level is WS-10c. Reliable enough, but still with relatively low service life. This is not leader, this is not catching up, there's a whole flock of earlier, similar and higher performing engines around the world.

That's not leader, that's mid-1990s production engine (core tech from 1980s) . I.e. this level of engine is like 40 years fresh.

Ws-15 has flown, but it isn't a production engine yet. Maybe next year, maybe the year after.

Same on ws-19 - excellent, but not yet. Same on ws-20 (first Chinese high bypass turbofan) - excellent, but not yet.
And now everyone is surprised that variable engine doesn't fly ahead of US. Like, we should be reasonable.

For the record, I'm not surprised at that (the bolded part) -- I am saying that we should be accurate in assessing PRC aeroengine capabilities, and an appropriate set of assumptions should be in place when trying to answer questions where the answers lie decisively in the state or future of PRC engine technology.

When China will become a leader - it will.
It's the single most difficult industrial catch-up of our time, not easy walk.
For now, especially if the goal is to get 50t fighter with fighter thrust to weight ratio(and additional power generation) - Chengdu has to either add an engine, or cut T:W, or produce a smaller bird in same class as J-20.
There's no magic.

That is my view as well, and the idea of a hypothetical three engine J-XD implies the first option you listed -- i.e.: their engine technology is expected to be insufficient to enable two engines to power the aircraft, thus they are choosing to add a third.

It remains to be seen whether a hypothetical three engine aircraft emerges, and if it does, whether the aircraft is of such a size and nature that would have required three engines even if it had access to foreign engine technology thus implying that PRC aeroengine technology and capability of the future is approximately similar with that of future engine tech and capability of global leaders, but right now I don't think we are in a position to entertain that as likely.