J-20 5th Gen Fighter Thread VI

[kurutoga]

Haters love to argue J-20's being longer means massive extra weight, as if the extra section is filled entirely of concrete or something.

I don't necessarily think people are haters. They have doubts, which are understandable. China has not been at the forefront of fighter jet design and manufacturing. It is hard to judge China's ability by past experience.

On the other hand, myself had been involved in some different projects, although not related to military, I know both electronics and manufacturing went through many great transformations, globally and especially in China, in the past 15 years. I know today is so much different than 1980s when F-22 was designed.

My suspicion is most people overestimated F-22's capability, they are the victims of propaganda. If J-20 has superior capabilities, we will gradually learn. For now most people can only speculate. You can't show how great the supersonic performance is in an airshow, you will blowout everybody's eardrums

 

[kurutoga]

The article starts with "based on expert reports from AIVC to ..., the unclassified data shows J-20 empty weight was controlled at 15 metric ton level". The likelihood of it being true is pretty high. How to explain it, the author mentioned a few advances in manufacturing methods in China, such as 80k ton forging press, ..., then he focused on three main technologies he thought helped during J-20 manufacturing:

• liquid metal electromagnetic shaping
• metal superplastic forming
• metal 3d printing

 

[Air Force Brat]

Unless the J-20 used some sort of extraterrestrial material or technique during its construction, it is simply impossible for it to have anot empty weight of under 19 metric tons. The J-20 has a longer fuselage than the F-22 and roughly the same cross-sectional area, which implies the same or greater empty weight even accounting for advances in material and manufacturing techniques.

Quite right Master Siege, and the reason Bro that you R a Super Moderator here on SDF,,, Logic, Reason, and Integrity,,, proud to see a man stand on those principles!

 

[Air Force Brat]

I don't necessarily think people are haters. They have doubts, which are understandable. China has not been at the forefront of fighter jet design and manufacturing. It is hard to judge China's ability by past experience.

On the other hand, myself had been involved in some different projects, although not related to military, I know both electronics and manufacturing went through many great transformations, globally and especially in China, in the past 15 years. I know today is so much different than 1980s when F-22 was designed.

My suspicion is most people overestimated F-22's capability, they are the victims of propaganda. If J-20 has superior capabilities, we will gradually learn. For now most people can only speculate. You can't show how great the supersonic performance is in an airshow, you will blowout everybody's eardrums

Heh?? really?? if anything the Raptor's full capabilities have NEVER been declassified,,, and it produces a great deal more static thrust in both dry and burner than the J-20 presently, and likely will produce in the future...

To illustrate further, even though the F-15 has a better thrust to weight ratio, the F-22 handily beats its climb rate....

so underestimate the Raptor to your hearts content,,, call its performance "propaganda",,,, but do so at the risk of your own integrity and credibility,,,, I would NOT lower myself to exaggerate the F-22s performance, but then I don't have to,,,, its an amazing aircraft, all you have to do is watch the video's,,, its def a very high performance aircraft,,,,

and you are right, nobody here should hate the J-20, its a lovely airplane with extremely high performance,,, I'd be very careful when comparing it to the F-22, to assume the J-20 is superior, with significantly less thrust does seem to defy the laws of physics, to assume its 25% lighter is a real stretch, and that's being very kind!

 

[kurutoga]

Heh?? really?? if anything the Raptor's full capabilities have NEVER been declassified,,, and it produces a great deal more static thrust in both dry and burner than the J-20 presently, and likely will produce in the future...

Having less empty weight may allow J-20 to carry more stuff but still achieve comparable TWR with a lower performing engine. That's what that article says. To review the overall capability of a jet we also need to have some idea of the electronics etc which are all classified. We have seen in some areas, at least in theory, China today can surpass US 30 years ago, for example some China made radar's real performance is unknown but from the specifications we think it is better than some US models designed a long time ago but are still in use in frontline units.

No one wants to disrespect any US technology, but I want to point out the reality. When I said someone could be overestimating F-22's capability, I meant exactly the open ended conclusions that will be eternally true. It was unreal in 1990s, it was fantastic in 2000s. but as time goes by, f-22 will become a classic some day, and obsolete eventually. The propaganda is not updated with time. But technology advances is real, it is happening each day and is accelerating. In some sense, the longevity is an enemy. Competitive advantage today must also include shorter design/modification/manufacturing cycle to better utilize recent tech advances

 

[manqiangrexue]

Heh?? really?? if anything the Raptor's full capabilities have NEVER been declassified,,, and it produces a great deal more static thrust in both dry and burner than the J-20 presently, and likely will produce in the future...

To illustrate further, even though the F-15 has a better thrust to weight ratio, the F-22 handily beats its climb rate....

so underestimate the Raptor to your hearts content,,, call its performance "propaganda",,,, but do so at the risk of your own integrity and credibility,,,, I would NOT lower myself to exaggerate the F-22s performance, but then I don't have to,,,, its an amazing aircraft, all you have to do is watch the video's,,, its def a very high performance aircraft,,,,

and you are right, nobody here should hate the J-20, its a lovely airplane with extremely high performance,,, I'd be very careful when comparing it to the F-22, to assume the J-20 is superior, with significantly less thrust does seem to defy the laws of physics, to assume its 25% lighter is a real stretch, and that's being very kind!

To assume J-20 is 4 tons lighter than Raptor without reason would be a stretch, but now, there is word from AVIC, the makers of the J-20, that that is the case. I'm not saying the reliability is indisputable, but that coupled with the many posts here that discuss how weight could have been saved (possible 3 ton loss on improved titanium alone, weight loss through DSI, omission of thrust vectoring, etc...) certainly makes the case for the possibility. Don't forget, the J-20 was designed specifically to be able to cope with inferior engines if needed. At this point, from what I can see, the only argument for why the J-20 could not possibly be that light goes along the lines of, "But USA couldn't make it that light 20 years ago! How could anybody do better than a 20-year old American design?" Well, that's called denial, not reasoning LOL Times are changing, and they change faster in China than anywhere else. Call it "extraterrestrial" if you want, but to many, the entirety of China's meteoric rise has seemed quite out-of-this-world.


I'm very glad you brought up the case of the F-15 having a superior TWR than the F-22 but under-performing when compared with the F-22. It shows that you realize that new, superior design can overcome TWR deficit. So how is it that you suddenly believe that there must be a "defiance of the laws of physics" for a 2016 J-20 with less thrust (though not necessarily lower TWR due to massive weight savings from cutting edge Chinese manufacturing techniques) to outperform a 2005 F-22 with more thrust? Seems entirely possible to me given your F-15 vs F-22 example, especially seeing as how the supercomputers used to calculate aerodynamics have had their capabilities evolve exponentially with time.

Now don't get me wrong. F-22's a lovely silver pony, still among the best in the world surely, but to assume that it's superior to a modern 5th gen delta canard made with cutting-edge manufacturing techniques and materials designed with the fastest supercomputers in the world all 20 years later in advancement... well, no need to finish that sentence, to be "kind" back to you.

 

[plawolf]

There have been pictures posted in this very thread of the J20’s main structural bulkheads manufactured with 3D printing technology that have significantly less material than the F22’s forged bulkheads. That alone might account for most of the 4ton less weight. The J20 is designed decades after the F22 after all, and manufacturing capabilities have advanced massively in that timeframe.

One also needs to bear in mind that planes like the F22, J20 and F35 are designed as much by supercomputers as they are by human experience and initiation.

More computing power would allow more accurate calculation of forces and stresses, and coupled with manufacturing advances, allow designers to either reduce the built-in structural safety margins with no risks or compromise in performance, and/or to achieve the same required structural strength with far less materials, like the main bulkhead example.

As others have already mentioned, the F22’s TVC nozzles carry a hefty weight penalty as well. It’s much larger vertical stablzers are not made out of air either. It all adds up.

American preference for multirole capabilities could also have influenced the F22’s design team to ‘future-proof’ the design by including core structures already rated for multirole strike mission weights and carriage profiles so they could easily add strike capabilities to the plane without needing significant structural redesign and new birds to be built.

OTOH, China is behind on engine tech, that’s news to no one, so why would people find it so unreasonable to think that Chinese engineers and designers would place a much higher priority on weight minimisation compared to their American counterparts who know they have monstrously powerful engines to play with?

Together with advances in materials science, manufacturing process and supercomputing power, it’s hardly unreasonable to think they could have aimed for a much lower empty weight compared to the F22 (to compensate for their weakness in engines) and achieved it.

 

[Inst]

I don't think the 15000 kg figure is fully credible, and needs to be substantiated by further sources of independent credibility. But it's not wholly impossible; the J-20 is known to have a 40% weight reduction in its titanium airframe courtesy of Chinese 3D printing technology, and its volume is approximately around that of the F-22's.

Given the F-22 is about 40% titanium by weight, this comes out to a reduction of 3000 kg, or around 16000 kg for the J-20.

 

[latenlazy]

I don't think the 15000 kg figure is fully credible, and needs to be substantiated by further sources of independent credibility. But it's not wholly impossible; the J-20 is known to have a 40% weight reduction in its titanium airframe courtesy of Chinese 3D printing technology, and its volume is approximately around that of the F-22's.

Given the F-22 is about 40% titanium by weight, this comes out to a reduction of 3000 kg, or around 16000 kg for the J-20.

It's the same as always. We have to wait and see.

 

[Totoro]

J20 is not approximatively of same volume as f22. I've myself calculated the volume to be some 20ish percent bigger. Now that doesn't need to be accurate, but it's fairly evident from the images that volume is bigger.