J-20 5th Generation Fighter VII

latenlazy said:

The point is that if they're using the method in a highly loaded part, that means the method is competitive in strength characteristics for that application. You can try to dance around the point but the utilization of the 3D printed part is self evident.

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Define "the method". Do they take a part straight from the printer, mill away the surface irregularities and use it as a fighter bulkhead or airliner wing spar? That's how I understand the claim, and I'm skeptical of such a part being up to the strength required in these applications.

If we're talking about a Chinese counterpart to Ampliforge, then I have no problems believing it. I'd just take grave issue with the characterization of the part as 3D printed then, for all the same reasons as nobody in their right mind would consider its F-22 equivalent a casting. Marketing may say differently (and I would even agree that it offers massive improvements in time an cost), but in the end it's still a machined forging, which gains its weight reduction from being machined, and its strength from forging.

latenlazy said:

Who else is printing 3D parts that big? The logic you're using is nonsensical for assessing *any* kind of engineering claim. It's like saying because Boeing is the only company using single piece carbon composites for the fuselage this technology must be unbelievable and imaginary.

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Anybody owning a Sciaky EBAM 150 since 2009 would come so close as to make virtually no difference, and with a 2016 EBAM 300 could print parts twice that size. You are also gravely misrepresenting my argument: it isn't "nobody else does it, so SAC/CAC cannot be doing it either" - that would indeed be nonsensical. It is in fact "others could do it but are not, and there are a couple of common sense reasons not to, so I'm not holding my breath". This may seem like mere nuance, but the two statements are in fact completely different in meaning.

latenlazy said:

You do know there has been a lot of research and development on different methods such as reducing grain size, developing melt or deposition patterns that can be post treated to generate specific grain patterns, and application of other kinds of post printing treatment that can drastically improve material strength right? SAC doesn't need to have done something hitherto unknown and magical in the world of 3D printing to make their 3D printed parts stronger.

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Yes. And I know that you are going to have a hard (if not completely impossible) time emulating what a conventional forging process does. Thermal effects are one thing, mechanical force is quite another. First principles.

latenlazy said:

Furthermore, you don't always need the part to match or exceed forging in every way. Strength just needs to be adequate enough to meet the engineering requirements.

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Not always, but in fighter fuselage bulkheads and airliner wing spars you do. Parts don't get subjected to a process which takes half a year and wastes 95% of the initial piece for giggles. The reason why this incredible expense is tolerated is because no other way to achieve the strength-to-weight ratio required for the application is available. Now, 3D printing the forging blank rather than starting with an ingot of extremely unfavourable aspect ratio cuts a lot of that time and waste, but it's not really what endows the part with the properties required.

latenlazy said:

You're basically employing the same logic as people 20 years ago who were skeptical of single piece carbon fiber being used for major structural parts in aerospace. Again, you keep treating the limitations of 3D printing like they're locked in laws of nature that can't be tractably addressed and resolved, when even a basic open source survey of the state of the technology will tell you that is clearly not the case.

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Not at all. There just are some qualities forging can instill in a part that are neigh impossible to achieve by 3D printing, due to, well, laws of nature indeed. I mean, sure - Arconic marketing wants us to consider Ampliforge a 3D printing process, but effectively it succeeds in providing properties equivalent to a forging by... actually forging the part.

latenlazy said:

As I've said before in a different post, use of 3D printing is not in of itself definitive evidence of weight saving. My main point in this round of exchanges was to address this notion that 3D printed parts couldn't possibly be used for load bearing structures.

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Fair enough. No issues with stating it like that, except perhaps the characterization of parts manufactured by certain processes as 3D printed. Again, this can seem like sophistry, but misguided assumptions often stem precisely from a lack of stringency in such regards.

taxiya said:

Isn't your argument kind of "I can not do it, so nobody can or it is useless, I don't understand so nobody do, I don't see it so it is not there."?

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No, not even kind of. Because:

1) I (if you insist on equating me personally with the leading non-Chinese aerospace industries, I guess I'll just take the compliment..) CAN actually do it, as I mention in the quote you so conveniently bolded. By "it" (and it's important to specify which part of the argument we are talking about here) I mean that I could build a J-35 or J-20 sized fighter with wing spars and fuselage bulkheads integrated into a single piece. 3D printing is not even a prerequisite for this.

2) If, despite having the ability, I don't do it, that means I'm either too stupid to realize the rather obvious structural advantage, or I have found good reasons not to do it. And a couple are readily apparent, for example it might be even better for the wing spars to be carbon fibre, as done on the Typhoon, Rafale and F-22. Or the damage repair problem mentioned earlier - do you really want to bin an entire airframe each time a wing takes some damage?

Note that I'm not saying the J-35 doesn't use this kind of construction, there are indications that it in fact does. I'm just questioning whether it's such a clever idea. Yes, even experienced engineering organizations occasionally get lured into dead ends, I'm sure you can quote me a list of Western aerospace OEMs' failures yourself, so I won't bother. Why would their Chinese peers be exempt from such pitfalls though?

taxiya said:

C919's wing root beams are 3D printed. They have been flying around for years while being closely examined and also being "abused" on the static test rig. Aren't these actions engineering and science?

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Wing/body fairing longerons are not fighter bulkheads. The requirements in terms of strength are vastly less onerous, and other aircraft are flying with 3D printed parts in comparable applications (though nowhere near as large, AFAIK).

Tirdent said:

No, not even kind of. Because:

1) I (if you insist on equating me personally with the leading non-Chinese aerospace industries, I guess I'll just take the compliment..) CAN actually do it, as I mention in the quote you so conveniently bolded. By "it" (and it's important to specify which part of the argument we are talking about here) I mean that I could build a J-35 or J-20 sized fighter with wing spars and fuselage bulkheads integrated into a single piece. 3D printing is not even a prerequisite for this.

2) If, despite having the ability, I don't do it, that means I'm either too stupid to realize the rather obvious structural advantage, or I have found good reasons not to do it. And a couple are readily apparent, for example it might be even better for the wing spars to be carbon fibre, as done on the Typhoon, Rafale and F-22. Or the damage repair problem mentioned earlier - do you really want to bin an entire airframe each time a wing takes some damage?

Note that I'm not saying the J-35 doesn't use this kind of construction, there are indications that it in fact does. I'm just questioning whether it's such a clever idea. Yes, even experienced engineering organizations occasionally get lured into dead ends, I'm sure you can quote me a list of Western aerospace OEMs' failures yourself, so I won't bother. Why would their Chinese peers be exempt from such pitfalls though?



Wing/body fairing longerons are not fighter bulkheads. The requirements in terms of strength are vastly less onerous, and other aircraft are flying with 3D printed parts in comparable applications (though nowhere near as large, AFAIK).

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For this idea, as with most PLA watching, we are often at a disadvantage of information.
When confronted with new ideas or suggestions or rumours, if something passes the proverbial smell test, then the next step is usually to consider circumstances in which an idea/rumour/suggestion may be true or viable.


So for this hypothesis, it's really a two step question:
1. Does the idea/rumour/suggestion pass the smell test? (I.e.: is it black and white simply "impossible")
2. If the idea/rumour suggestion passes the smell test (i.e.: "not impossible"), then what are the prerequisite circumstances/technologies/capabilities that would have to be resolved for it to be likely to make sense and be viably implemented?

Patchwork_Chimera said:

It varies by Brigade, but yes we're seeing ~ 30 multirole airframes, with 24 expected as PMAI airframes, 4-5 as part of the training flight group [dadui] (大队), and 1-2 airframes either as attrition reserve inventory, or in other bespoke roles for the Brigade. We also expect to see slightly different configurations primarily based on aircraft type, wherein for example a J-20 Brigade of J-20s and J-20Ss may be structured with 24 PMAI single seaters, ~4 (one flight group/大队) of PMAI dual seaters, 4 PTAI dual seaters, 2-4 attrition reserve/bespoke task airframes. It's a semi-firm belief that J-16+J-16D composite brigades may be organized according to a similar ethos - rather than being put into specialized units or subordinated to EW brigades.

It's sorta loosey goosey at the moment though. The PLA is really, annoyingly good at obfuscating a lot of their structural specifics.

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But if PLAAF is good at obfuscating specifics, then how can anyone say "we're seeing this and that number of planes per unit"?

I mean, what sort of actual indications are there that there are indeed 30 planes per J16 and/or J20 units?

One set of indications (not a good one, i know) could be the numbers of shelters near the apron. For example, J10 units often had 28 such shelters. And that meshed well with the expectation/knowledge/assumption that J10 units indeed operated 28 planes.

But then we also have airbases which operate a single brigade of j11, j16 or j20 and they have a different number of shelters. Some have just 24. But some have 28 and some up to 36.

Specifically, of the J-16 brigades that do not share their airbase with any other unit, and of those that have shelters (most do not) one J16 brigade unit has 24 and one has 28 shelters.

Of the J-20 brigades that do not share their airbase with any other unit, and of those that have shelters, one J20 brigade unit has 24, one one has 28 shelters, one has 36 (with 12 shelters being on the other side of the base, away from other 24 shelters) and another one has 36 where 8 shelters are separate and 28 are grouped.

PLAAF J-11B units, again when not sharing an airbase and when having shelters in the first place: one has 28 (24 grouped and 4 more on the other side of the airbase), two have 32 (24 grouped and another 8 grouped on the other side), one has 23 (10 grouped and another 13 grouped), one has 36.

The above lists do not include hardened shelters though. (as a separate note, those have started appearing more and more on PLAAF bases in recent years)

But crucially - all the lists above are really inconclusive. They can't be indicative of much, as there are way too many plausible explanations for the number of simple shelters being unconnected to the actual number of planes within a brigade.

So... one again, are there any good indications that would help unravel this mystery? Or does PLAAF really have no overreaching standard for the number of planes within a brigade? And perhaps PLAAF really has some j20 brigades equipped with fewer planes, some equipped with more, and the same lack of standard being applicable to J-16 and even J-11B brigades?

Totoro said:

But if PLAAF is good at obfuscating specifics, then how can anyone say "we're seeing this and that number of planes per unit"?

I mean, what sort of actual indications are there that there are indeed 30 planes per J16 and/or J20 units?

One set of indications (not a good one, i know) could be the numbers of shelters near the apron. For example, J10 units often had 28 such shelters. And that meshed well with the expectation/knowledge/assumption that J10 units indeed operated 28 planes.

But then we also have airbases which operate a single brigade of j11, j16 or j20 and they have a different number of shelters. Some have just 24. But some have 28 and some up to 36.

Specifically, of the J-16 brigades that do not share their airbase with any other unit, and of those that have shelters (most do not) one J16 brigade unit has 24 and one has 28 shelters.

Of the J-20 brigades that do not share their airbase with any other unit, and of those that have shelters, one J20 brigade unit has 24, one one has 28 shelters, one has 36 (with 12 shelters being on the other side of the base, away from other 24 shelters) and another one has 36 where 8 shelters are separate and 28 are grouped.

PLAAF J-11B units, again when not sharing an airbase and when having shelters in the first place: one has 28 (24 grouped and 4 more on the other side of the airbase), two have 32 (24 grouped and another 8 grouped on the other side), one has 23 (10 grouped and another 13 grouped), one has 36.

The above lists do not include hardened shelters though. (as a separate note, those have started appearing more and more on PLAAF bases in recent years)

But crucially - all the lists above are really inconclusive. They can't be indicative of much, as there are way too many plausible explanations for the number of simple shelters being unconnected to the actual number of planes within a brigade.

So... one again, are there any good indications that would help unravel this mystery? Or does PLAAF really have no overreaching standard for the number of planes within a brigade? And perhaps PLAAF really has some j20 brigades equipped with fewer planes, some equipped with more, and the same lack of standard being applicable to J-16 and even J-11B brigades?

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Considering that the PLAAF is undergoing modernization, reorganisation, and retirement of new, current and obsolescent fighter aircraft all at the same time, I think it's a bit unreasonable to expect conclusive, nation spanning consistent evidence.

At the moment, the most likely working hypothesis is that a threshold fighter brigade strength is 30 aircraft, but we aren't going to see consistent, nation spanning evidence for that given the ongoing modernization+reorganisation+retirement that is happening at the same time.



New aircraft being produced are likely being introduced to different units simultaneously at the same time rather than completing delivery to one brigade to full strength before moving to the next, infrastructure is being built and upgraded to accommodate new aircraft and to account for unit reorganisation, and older obsolete aircraft are being retired.
All of that, combined with the PLA's deliberate opsec towards hiding fighter serials, and given Chinese aviation photographers' understanding of the sensitivity of serials and evidence for basing --- well I think we should recalibrate our expectations a little bit and express some gratitude to the orbat gods for letting us even develop a tentative working hypothesis that brigades are likely to be at 30 aircraft intended strength.



Our information for PLA fighter orbats are always going to be out of date and incomplete, perhaps by months or even years in disparity. But if your original question was "how many J-20s are likely to be in a standard brigade at intended strength" -- the best answer we have right now is "likely 30".

No, my question was not how many planes are there. My question is: What solid images/web links/publications/news bites that do we have, that could serve as indications for any specific number of J-20 planes per brigade? Without that question answered, there can be no "likely 30" answer, as any such answer must have *some* basis behind it.

Tirdent said:

No, not even kind of. Because:

1) I (if you insist on equating me personally with the leading non-Chinese aerospace industries, I guess I'll just take the compliment..) CAN actually do it, as I mention in the quote you so conveniently bolded. By "it" (and it's important to specify which part of the argument we are talking about here) I mean that I could build a J-35 or J-20 sized fighter with wing spars and fuselage bulkheads integrated into a single piece. 3D printing is not even a prerequisite for this.

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I am not equating you personally with any aerospace industry. I am just saying that you believe in the "looser" more than a winner.

You can make a single piece titanium bulkhead by forging. Nobody denied that. I didn't, what is your point? You can even make a single piece bulkhead with wood in even shorter time if you want to play the game of twisting.

I said (and you are trying to twist) that YOU CAN NOT make a single piece bulkhead in a few days by 3D printing.

3D printing is a prerequisite for doing it in a very short time and therefor lower the cost significantly.

The subject is around "3D printing". Don't pretend you did not know.

Tirdent said:

2) If, despite having the ability, I don't do it, that means I'm either too stupid to realize the rather obvious structural advantage, or I have found good reasons not to do it. And a couple are readily apparent, for example it might be even better for the wing spars to be carbon fibre, as done on the Typhoon, Rafale and F-22. Or the damage repair problem mentioned earlier - do you really want to bin an entire airframe each time a wing takes some damage?

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Everybody with some basic engineering background would realize the obvious structural advantage. You do not find any reason not to do it. But you are not able to solve the problem in perfecting 3D printing.

3D printing's problem is to reduce little gas holes in the product during the process. This is the roadblock preventing YOU to make 3D printing useful. Your inability of overcoming this problem is your "good reason" not to do it.

Your "problem/good reason" is solved by multiple Chinese teams including Wang Huaming. We don't have your problem. We don't have your "good reason" not to do it.

Once again, this is why I said your argument is kind of "I can not do it, so nobody can or it is useless, I don't understand so nobody do, I don't see it so it is not there."

Tirdent said:

Note that I'm not saying the J-35 doesn't use this kind of construction, there are indications that it in fact does. I'm just questioning whether it's such a clever idea. Yes, even experienced engineering organizations occasionally get lured into dead ends, I'm sure you can quote me a list of Western aerospace OEMs' failures yourself, so I won't bother. Why would their Chinese peers be exempt from such pitfalls though?

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Yes I can quote Western OEM's failure. AeroMet is quoted by Wang Huaming as the failed example in his presentation about 3D printing.

2001年美国AeroMet公司开始为波音公司F/A-18E/F舰载联合歼击/攻击机小批量试制发动机舱推力拉梁、机翼转动折叠接头、翼梁、带筋壁板等机翼钛合金次承力结构件。2002年制定出了“Ti6Al4V钛合金激光快速成形产品”宇航材料标准(ASM 4999)并于同年在世界上率先实现激光快速成形钛合金次承力结构件在F/A-18等战机上的验证考核和装机应用。然而,令人遗憾的是,由于未能有效解决激光快速成形大型钛合金结构件内部质量和力学性能控制等关键技术难题,其激光快速成形Ti6Al4V等钛合金结构件,即使再经热等静压(HIP)、开模锻造(open-die forging)等后续致密化加工,其疲劳等关键力学性能仍然显著低于钛合金锻件(如图1所示[2],优于铸件而低于锻件),难以取代锻件实现其在飞机主承力构件上的应用,AeroMet公司最终于2005年12月被迫停业关闭

AeroMet was the first in the world to make 3D printed titanium load baring component for F/A-18 in 2002. AeroMet could not solve the problem of 3D printing EVEN after using post-processing HIP and open-die forging. It was a failure. AeroMet bankrupted in 2005.

Chinese peers are not exempt from any pitfalls. While you fell into the pitfall, Chinese solved the problem. It is just that simple.

Tirdent said:

Wing/body fairing longerons are not fighter bulkheads. The requirements in terms of strength are vastly less onerous, and other aircraft are flying with 3D printed parts in comparable applications (though nowhere near as large, AFAIK).

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I didn't say that, did I? But they are load baring component, aren't they?

In the same presentation and quoted in my post, an unnamed fighter jet's bulkhead is 3D printed and it was tested for more than 8000 hours and more than a year. Did you read it?

It is also well-known that 3D printed parts are used in many aircraft worldwide, nobody said otherwise, so again what is your point?

It seems that you selectively avoid the inconvenient evidence and pick some common sense that nobody reject. I see this as a well-know tactic in getting away from a debate.

From all your posts, the only conclusion that I can reach is that "you simply can not accept the possibility or reality that China can do something that the others can not." In the attempt of denial, you come up with the "common sense" and most importantly "there must be some pitfalls that China is hiding or not seeing. Even if China solved pitfall 1 there must be pitfall 2 down the road that is not revealed yet."

Blitzo said:

For this idea, as with most PLA watching, we are often at a disadvantage of information.
When confronted with new ideas or suggestions or rumours, if something passes the proverbial smell test, then the next step is usually to consider circumstances in which an idea/rumour/suggestion may be true or viable.


So for this hypothesis, it's really a two step question:
1. Does the idea/rumour/suggestion pass the smell test? (I.e.: is it black and white simply "impossible")
2. If the idea/rumour suggestion passes the smell test (i.e.: "not impossible"), then what are the prerequisite circumstances/technologies/capabilities that would have to be resolved for it to be likely to make sense and be viably implemented?

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The "fighter jet 3D printing bulkhead" is not said by someone unknown. It is said by Wang Huaming, a member of China Academy of Engineering in a presentation which is posted in this forum not long ago when Tirdent is a active member. According to Wang's personal introduction on China Academy of Engineering website, SAC and XAC among others are main sponsors and partners of his work.

I honestly don't see how Tirdent could call this revelation as mere idea, rumour or suggestion that need to go through the suggested steps of test. So I won't entertain him down this path. Neither dare he call Wang Huaming a liar from his (Tirdent) professional background whatever that may be. So he hide himself behind "reasonable doubt" from his own "common sense". There is no way to convince a person in such mental condition to open up to any other inconvenient possibilities. It is not a technical, fact and evidence based debate but a mental and emotional argument.

Put it another way, if we switch SAC and XAC with LM and Boeing, switch Wang Huaming with chief scientists of LM or a subcontractor with prestige title in US engineering community, switch J-20 with F-22, will Tirdent come up with the same line as "because Russian and Chinese is not doing it, so I doubt Americans can do it, there must be some pitfalls that US will fall in down the road"? I don't believe we will hear anything from him.

taxiya said:

The "fighter jet 3D printing bulkhead" is not said by someone unknown. It is said by Wang Huaming, a member of China Academy of Engineering in a presentation which is posted in this forum not long ago when Tirdent is a active member. According to Wang's personal introduction on China Academy of Engineering website, SAC and XAC among others are main sponsors and partners of his work.

I honestly don't see how Tirdent could call this revelation as mere idea, rumour or suggestion that need to go through the suggested steps of test. So I won't entertain him down this path. Neither dare he call Wang Huaming a liar from his (Tirdent) professional background whatever that may be. So he hide himself behind "reasonable doubt" from his own "common sense". There is no way to convince a person in such mental condition to open up to any other inconvenient possibilities. It is not a technical, fact and evidence based debate but a mental and emotional argument.

Put it another way, if we switch SAC and XAC with LM and Boeing, switch Wang Huaming with chief scientists of LM or a subcontractor with prestige title in US engineering community, switch J-20 with F-22, will Tirdent come up with the same line as "because Russian and Chinese is not doing it, so I doubt Americans can do it, there must be some pitfalls that US will fall in down the road"? I don't believe we will hear anything from him.

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Don’t you see, Chinese engineering advancement can only progress to a point behind western technical cutting edge, because how else can the west maintain their decades old lie that China cannot innovate and can only copy the master race if China develops something they don’t have themselves?

Guys, this is the J-20 thread.