J-20 5th Gen Fighter Thread VI

[jobjed]

Why should we take a pretty extraordinary claim seriously?

In isolation, we shouldn't, because the probability of its being true is negligible. However, the source that it came from is more legitimate than normal so, based on what we know and can know, the probability of the claim's being true is now firmly out of "negligible" territory.

 

[Klon]

In isolation, we shouldn't, because the probability of its being true is negligible. However, the source that it came from is more legitimate than normal so, based on what we know and can know, the probability of the claim's being true is now firmly out of "negligible" territory.

Can you tell me the name of the trade magazine, or are you referring to an online source?

 

[latenlazy]

Thanks for the response. I'd like to ask you what your position is on the 15 tonne question, as you've generally made arguments in favor, but also expressed skepticism, particularly at the start of the discussion.
Do you think the weight is 15 tonnes or that it could be that? If the latter, what probability do you assign it?
If it's just that it could be 15 tonnes, do you acknowledge that it could be something else, e.g. 21 tonnes (which I take to be some kind of 'conventional' estimate) or 25 tonnes?
Why should we take a pretty extraordinary claim seriously?

The honest answer is I don’t know and, frankly, between 15 or 21 tonnes I don’t feel strongly about it either way. You can make a case for both. That said, for the J-20’s weight to be exorbitantly greater relative to its peers (such as 25 tonnes) would require believing either the PLAAF wasn’t aiming for a competitive fighter, or that they’re incapable of producing something that would fit the specs of a competitive fighter, or that they’re incompetent. We know from everything officials have said publicly and from documents like the program tender that the J-20 is supposed to be a competitive fighter to the F-22 though, and any three of those assumptions smacks of the sort of condescending biases and baseless prejudices that have led to underestimation of potential adversaries before (as we seem to be getting daily reminders of from NK of late). Irregardless of how you reason it though the only answer that matters is sitting in a spec sheet somewhere out of reach from our prying eyes. Everything else is presumptive speculation.

The main reason right now for taking the 15 tonne claim at least somewhat seriously is that the claim would be consistent with a comment made by AVIC Laser in 2013 that if the F-22’s titanium frame were made with their 3D printing process they could reduce its weight in titanium by 40%. Maybe this means the writer of the trade magazine article from whence the 15 tonne claim originates calculated a hypothetical weight assuming the J-20’s weight and Ti composition was in the ballpark of the F-22’s but for the titanium weight savings, or maybe they’re actually in the know about something as someone from within the industry. Maybe they’re just citing airframe weight with nothing else installed (though the article makes the weight claim in comparison to the F-22’s empty weight).

When weighing the reliability of these claims though I think it’s important to ask if China *could* make a 15 tonne J-20 with most or all of the bells and whistles, why wouldn’t they? If we don’t believe they could, why not? Right now the answer to why they couldn’t seems to hinge more or less on “because others (who are assumed to be technologically superior in everything) haven’t yet”. That sort of reasoning usually reflects retrograde (and often character based) subjective judgments rather than assessment based on technical merit, which of course will naturally be short in supply in what surmounts to, with minor exception, a discussion between lay persons in a hobby forum (as I hope my forum mates here don’t mind me saying).

Furthermore, to think China couldn’t seems to indirectly contradict an explicit comment that might suggest otherwise from within their industry, which usually hasn’t made doubters look particularly shrewd in the past. This is why I think it would be hasty and perhaps more than a little foolish to simply dismiss the idea as impossible because it sounds unbelievable. After all, subjective disbelief isn’t what determines what actually is or isn’t possible, and we are talking about state of the art in a country that’s doggedly trying to push the frontiers of their technology to surpass rivals. There’s a time and place for laughing at ridiculous claims, but so far this one hasn’t fit the usual fact patterns that would let us do so. That doesn’t mean we should abandon skepticism or that there isn’t anything to be skeptical of, but if we’re applying skepticism in an even handed and objective manner, reactions of dismissal or incredulous denial shouldn’t be exempt from scrutiny either.

 

[siegecrossbow]

Can you tell me the name of the trade magazine, or are you referring to an online source?

It came from a trade magazine called 兵工科技 (Military Tech).

 

[latenlazy]

Can you tell me the name of the trade magazine, or are you referring to an online source?

It came from a trade magazine called 兵工科技 (Military Tech).

Here's the original post with the source attached.
#358

 

[latenlazy]

Before I get caught for this, I should point out I just realized the second F-22 bulkhead image is right after forging and hasn't been milled yet, so probably not a good point of comparison. I'm also unsure about the first image. Much appreciated if someone has a better image for comparison.

EDIT: Maybe this one can serve for a better comparison, though it might weaken my point.


EDIT 2: Trident, earlier you were talking about hollowed structures or structures with trusses made from 3D printing. Though perhaps not with the bulkheads, it seems we might have our answer here, at least with some parts here. #4997

 

[Klon]

That said, for the J-20’s weight to be exorbitantly greater relative to its peers though (such as 25 tonnes) would require believing either the PLAAF wasn’t aiming for a competitive fighter, or that they’re incapable of producing something that would fit the specs of a competitive fighter, or that they’re incompetent. We know from everything officials have said publicly and from documents like the program tender that the J-20 is supposed to be a competitive fighter to the F-22 though, and any three of those assumptions smacks of the sort of condescending biases and baseless prejudices that have led to underestimation before.

Alternatively, fighter development is an extremely complex undertaking and weight creep is commonly seen in programs around the globe. The 611 Institute doesn't have to be incompetent or incapable to be forced into trade-offs that could result in a weight greater than the 'baseline' 21 tonnes. I'm not saying that this actually happened, just that it is not something that can be obviously ruled out.
I don't find imputation of negative motives, even without direct attribution, to be conducive to good faith discussion.

The main reason right now for taking the 15 tonne claim at least somewhat seriously is that the claim would be consistent with a comment made by AVIC Laser in 2013 that if the F-22’s titanium frame were made with their 3D printing process they could reduce its weight in titanium by 40%. Maybe this means the writer of the trade magazine article from whence the 15 tonne claim originates calculated a hypothetical weight assuming the J-20’s weight and Ti composition was in the ballpark of the F-22’s but for the titanium weight savings, or maybe they’re actually in the know about something as someone from within the industry. Maybe they’re just citing airframe weight with nothing else installed (though the article makes the weight claim in comparison to the F-22’s empty weight).

Thank you for the information (seriously).

When weighing the reliability of these claims though I think it’s important to ask if China *could* make a 15 tonne J-20 with most or all of the bells and whistles, why wouldn’t they? If we don’t believe they could, why not? Right now the answer to why they couldn’t seems to hinge more or less on “because others (who are assumed to be technologically superior in everything) haven’t yet”. That sort of reasoning usually reflects retrograde (and often character based) subjective judgments rather than assessment based on technical merit, which of course will naturally be short in supply in what surmounts to, with minor exception, a discussion between lay persons in a hobby forum (as I hope my forum mates here don’t mind me saying).

Furthermore, to think China couldn’t seems to indirectly contradict an explicit comment that might suggest otherwise from within their industry, which usually hasn’t made doubters look particularly shrewd in the past. This is why I think it would be hasty and perhaps more than a little foolish to simply dismiss the idea as impossible because it sounds unbelievable. After all, subjective disbelief isn’t what determines what actually is or isn’t possible, and we are talking about state of the art in a country that’s doggedly trying to push the frontiers of their technology to surpass rivals. There’s a time and place for laughing at ridiculous claims, but so far this one hasn’t fit the usual fact patterns that would let us do so. That doesn’t mean we should abandon skepticism or that there isn’t anything to be skeptical of, but if we’re applying skepticism in an even handed and objective manner, reactions of dismissal or incredulous denial shouldn’t be exempt from scrutiny either.

This is what I wanted to discuss. In the absence of published technical data and specifications from China, how does one decide what to think about these issues?

Personally, I believe Chinese sources that have been proven to be credible, from forum insiders such as maya and pop3 to He Weirong (J-20 deadlines) and Ma Xiaotian (H-20 "soon"). On the other hand, Yin Zhou and Zhang Zhaozhong, both rear admirals, are well-known for often being wrong on TV.

When it comes to technical claims, it is indeed very hard to say anything without expertise and access to specifications. I don't assume that China couldn't be (isn't) ahead of the U.S. in some areas, and the number of these areas is sure to grow. However, there are claims that are hard to square with my understanding of things (model, if you like). For example,

• according to
  Please, Log in or Register to view URLs content!
  , an NRIET official said at Zhuhai 2016 that the AESA developed for the JF-17 has a range equivalent to the F-35's radar, achieved in a smaller volume radar;
• the claim that China's electromagnetic catapult is more advanced than America's;
• the 15 tonne claim.

I find these claims between quite and extremely implausible, but cannot prove that they aren't true. However, consider the reverse: would you be willing to believe an American claim saying that America's least important AESA, smaller and for export only, has equivalent range to J-20's radar?
If China's EMALS program started first, reached every milestone first and was much more open about its progress, would you believe an American claim that theirs was more advanced?
Similarly for the weight issue, if China was on the cutting edge of fighter development for the last 70 years, had four fourth generation designs in service and two stealth planes in service before it's first stealth fighter, would you be willing to believe that the first American stealth fighter, while larger than the first Chinese one, is nearly five tonnes lighter?

 

[latenlazy]

Alternatively, fighter development is an extremely complex undertaking and weight creep is commonly seen in programs around the globe. The 611 Institute doesn't have to be incompetent or incapable to be forced into trade-offs that could result in a weight greater than the 'baseline' 21 tonnes. I'm not saying that this actually happened, just that it is not something that can be obviously ruled out.

Some part of that is assuming Chinese aerospace isn't up to meet that challenge though, and if you delve into the "why" behind that question sometimes the reasons are grounded in some rather flippant or unpleasant beliefs. The PLAAF tendered for a fighter that could match the F-22, and the PLAAF is purported to be very happy with the J-20.

I don't find imputation of negative motives, even without direct attribution, to be conducive to good faith discussion.

Neither do I, but I think sometimes negative motives are implicit even if they're not intentional.

I find these claims between quite and extremely implausible, but cannot prove that they aren't true. However, consider the reverse: would you be willing to believe an American claim saying that America's least important AESA, smaller and for export only, has equivalent range to J-20's radar?
If China's EMALS program started first, reached every milestone first and was much more open about its progress, would you believe an American claim that theirs was more advanced?
Similarly for the weight issue, if China was on the cutting edge of fighter development for the last 70 years, had four fourth generation designs in service and two stealth planes in service before it's first stealth fighter, would you be willing to believe that the first American stealth fighter, while larger than the first Chinese one, is nearly five tonnes lighter?

I would if the evidence available was strong enough to make the idea plausible, and if America generally had a proven record of closing the technology gap and showed the prerequisite investment in time, effort, money, and manpower to do so, by either honest or illicit means. (And in fact, this is exactly what happened when America took the technology crown from Europe). If J-20 production started 20 years ago, it might not be so hard to believe that an American design coming out today could shave 5 tonnes if it dropped some requirements like multirole strike capability and experienced a few advances in manufacturing technologies. (I imagine the F-35 would have been much lighter if it were a pure air superiority fighter and Lockmart had to design it without being able to rely on reliable increases in engine power). As I've said before, subjective disbelief is not where the bounds of possibility are drawn. The "experience" argument in particular, I've found, is often overplayed to the great detriment of incumbents in the history of technological development. This is particularly true for technologies built on new operating principles and paradigms. Past performance is rarely the limiting factor in determining future performance, and I think people should be careful not to build their sense of what is believable on its sometimes tenuous logic.

"Larger" can be deceptive. We don't know the actual volume of the thing. Trident's approximate exercise showed a J-20 that was only larger than an F-22 by about 10% in volume. With some fudge factors around the margins, that could easily go up or down another 10%.

 

[Klon]

Some part of that is assuming Chinese aerospace isn't up to meet that challenge though, and if you delve into the "why" behind that question sometimes the reasons aren't grounded in anything analytically sound. The PLAAF tendered for a fighter that could match the F-22, and the PLAAF is purported to be very happy with the J-20.

It's pretty hard to know how happy they are or aren't, but they can be happy even if the weight is 21 tonnes or more. Just because the plan was to match the F-22 doesn't mean that they fully succeeded. We know that the J-20 isn't flying with the WS-15 yet. Plus, the weight of the plane being proportional to its volume is not a failure.

Neither do I, but I think sometimes negative motives are implicit even if they're not intentional.

Must be great to offer notes on decorum to others but reject any offered to you.

I would if the evidence available was strong enough to make the idea plausible, and if America generally had a proven record of closing the technology gap and showed the prerequisite investment in time, effort, money, and manpower to do so, by either honest or illicit means. (And in fact, this is exactly what happened when America took the technology crown from Europe). If J-20 production started 20 years ago, it might not be so hard to believe that an American design coming out today could shave 5 tonnes if it dropped some requirements like multirole strike capability and experienced a few advances in manufacturing technologies. (I imagine the F-35 would have been much lighter if it were a pure air superiority fighter and Lockmart had to design it without being able to rely on reliable increases in engine power). As I've said before, subjective disbelief is not where the bounds of possibility are drawn. The "experience" argument in particular, I've found, is often overplayed to the great detriment of incumbents in the history of technological development. This is particularly true for technologies built on new operating principles and paradigms. Past performance is rarely the limiting factor in determining future performance, and I think people should be careful not to build their sense of what is believable on its sometimes tenuous logic.

I still hope you'll answer for all three specific scenarios. Can you honestly say you would accept those American claims? Although I know your position on the last two, do you think the KLJ-7A has the same range as the AN/APG-81?

"Larger" can be deceptive. We don't know the actual volume of the thing. Trident's approximate exercise showed a J-20 that was only larger than an F-22 by about 10% in volume. With some fudge factors around the margins, that could easily go up or down another 10%.

Are you sure about the 10%? If you multiply his fuselage cross section numbers with the fuselage length you get about 30% more volume for the J-20. He doesn't agree with thinner wings for the J-20 and the difference in various stabilizers isn't that big. Keep in mind that he was doing a best case scenario for the J-20, i.e. his assumptions were already favorable. Although it's true that his ultimate mass estimate was 21.2 tonnes versus 19.7 tonnes, a difference of less than eight percent.
I also don't think it's fair to constantly question others estimates without providing your own.

 

[FORBIN]

Alternatively, fighter development is an extremely complex undertaking and weight creep is commonly seen in programs around the globe. The 611 Institute doesn't have to be incompetent or incapable to be forced into trade-offs that could result in a weight greater than the 'baseline' 21 tonnes. I'm not saying that this actually happened, just that it is not something that can be obviously ruled out.
I don't find imputation of negative motives, even without direct attribution, to be conducive to good faith discussion.

Thank you for the information (seriously).

This is what I wanted to discuss. In the absence of published technical data and specifications from China, how does one decide what to think about these issues?

Personally, I believe Chinese sources that have been proven to be credible, from forum insiders such as maya and pop3 to He Weirong (J-20 deadlines) and Ma Xiaotian (H-20 "soon"). On the other hand, Yin Zhou and Zhang Zhaozhong, both rear admirals, are well-known for often being wrong on TV.

When it comes to technical claims, it is indeed very hard to say anything without expertise and access to specifications. I don't assume that China couldn't be (isn't) ahead of the U.S. in some areas, and the number of these areas is sure to grow. However, there are claims that are hard to square with my understanding of things (model, if you like). For example,

• according to
  Please, Log in or Register to view URLs content!
  , an NRIET official said at Zhuhai 2016 that the AESA developed for the JF-17 has a range equivalent to the F-35's radar, achieved in a smaller volume radar;

The range you have see is not for same target size for 2 radars,
170 km vs 10 m2 for KLJ7-A AESA others with this number of modules by ex. ES-05 Raven, APG-80 have about this range APG-80 195 km
And 240 km for 5 m 2 for APG-81... 1676 modules vs about 1000 - 1100 in more !

Make completely sense as some have say in JF-17 topic recently the bird is cheaper and don't make sense expensive powerful radar..