Shenyang / Chengdu "6th Gen" Aircraft - General Discussion and Speculation

yeetmahboi said:
I can see how the twin aperture factors in that equation. Not many existing AAMs are armoured enough anyway, and I'm not sure if the boundary air surrounding an AMRAAM is hot enough to render even a measly 50kw laser useless, especially when the missile is in its last-mile cruise phase and slowing down.
Click to expand...

It seems extremely doubtful those apertures support any kind of DEW. A laser would not use a large sensor window; it would use a trainable mirror. And if the goal was shooting down missiles, then only arming along the frontal arc shows a lot of faith in the system and the pilots - since they would not be able expose their tail in a fight.
 
Josh_TN said:
It seems extremely doubtful those apertures support any kind of DEW. A laser would not use a large sensor window; it would use a trainable mirror. And if the goal was shooting down missiles, then only arming along the frontal arc shows a lot of faith in the system and the pilots - since they would not be able expose their tail in a fight.
Click to expand...
I won't go out of line and claim that those dual apertures are 100% super lasers either, only time will tell. But putting giga sized facets purely for IRST also doesn't seem like it unless the PLAAF is betting all in for some breakthrough in passive ranging.
 
yeetmahboi said:
I won't go out of line and claim that those dual apertures are 100% super lasers either, only time will tell. But putting giga sized facets purely for IRST also doesn't seem like it unless the PLAAF is betting all in for some breakthrough in passive ranging.
Click to expand...
That does make sense, and it isn't even first such solution(see xf-108 rapier and yf-12), and here we need stealth(no, facetted solution isn't ideal).

Laser with any energy to speak of almost certainly will not work well through such window; it's already a type of weapon system built around rather delicate balance of heat at both ends.
 
All the heat from lasers and whatever AESA they put there has to go somewhere tho. Anyone speculated yet on how much say, fuel carried by the J-36 ? That will determine the cooling capacity available to the airframe. Which in turn capped how much power you can put in your lasers or radars/avionics.

The fuel will act as heatsink, absorbing the heat and those heat will seep out to the environment through the fuel tank wall. Thus making the wing tank ideal as it provide volume and potentially large surface area to dissipate the heat. So more fuel = more cooling capacity.

I have made some crude estimate on fuel capacity based on the reference wing area of 184 sqm for J-36. I have to devise correction factor tho as the equation is based on airliner wing fuel capacity. It yield me some 10 metric tonne of fuel in the wing. the next step would be the ratio of how much is likely stored in wing vs fuselage. 50% ratio (F-15 does have about 48% of internal fuel in wing) Thus the total fuel capacity for the airframe is 20 metric tonne.

Using that value and use the linear regression equation i developed based on known aircraft cooling. This can give some cooling capacity of 111 KW/sqm of aperture area. Not everything tho goes into avionics.. only about 39% of those. Thus for radar 43.3 KW/sqm

laser is i'm curious how much.. Like radar tho it depends on power and dimension available to the aperture.
 
stealthflanker said:
All the heat from lasers and whatever AESA they put there has to go somewhere tho. Anyone speculated yet on how much say, fuel carried by the J-36 ? That will determine the cooling capacity available to the airframe. Which in turn capped how much power you can put in your lasers or radars/avionics.
Click to expand...
I was assuming something in the neighborhood of 40+klbs of fuel for the big USAF NGAD concepts, and the J36 seems to be designed to many of the same concepts.


stealthflanker said:
laser is i'm curious how much.. Like radar tho it depends on power and dimension available to the aperture.
Click to expand...
Lasers are notoriously inefficient.

For sake of discussion let's assume a 50kw laser.

Old designs you'd be talking 450kw of heat to dump out, high end new designs somewhere around 50-150kw. Personally, I'd assume around needing to dump 100kw of heat from the laser.
 
siegecrossbow said:
Chengdu patent for flexible aeilron.

CN115871915A - Large-angle continuous variable camber aileron based on compliant variant structure - Google Patents

The invention belongs to the technical field of flexible aileron structure design, and particularly relates to a large-angle continuous variable camber aileron based on a compliant variant structure, which comprises the following components: the aircraft comprises an inner wing section back...
patents.google.com

View attachment 759694
View attachment 759695
Click to expand...

I feel like this is interesting enough to belong in the more serious non-speculation thread.
 

Attachments

  • Aircraft_Fighter_Jet_F-111_AFTI_NASA_0.jpg
    Aircraft_Fighter_Jet_F-111_AFTI_NASA_0.jpg
    601.7 KB · Views: 62
ar020 said:
i wonder what type of material they use for the flexing part. Any ideas?
Click to expand...
Sufficiently thin composite panels, with a different resin than usual. For example, the inside walls of the baggage compartment of a 727 were some fiberglass panel that you just flexed to shape. The flat floor over the keel stringers was aluminum.
 
stealthflanker said:
yeah, this is important.

Also the specualtion images does really way too look like some Chinese CG.. it even still has the Axisymmetric nozzle depiction.
Click to expand...
Exactly... What length/wingspan/leading edge sweep did you use on your 3D model?
 
It just occurred to me:

What if the role of this plane is to change U.S. wargames/simulations of a battle over Taiwan? Even suggesting the existence of a relatively low observable supercruising long ranged PL-17 thrower that can attack from unexpected directions might be enough to prevent U.S. wargames from suggesting an easy victory (even with the inclusion of platforms like the B-21 or NGAD in the simulation).

A kind of conventional computational deterence.
 
Avimimus said:
It just occurred to me:

What if the role of this plane is to change U.S. wargames/simulations of a battle over Taiwan? Even suggesting the existence of a relatively low observable supercruising long ranged PL-17 thrower that can attack from unexpected directions might be enough to prevent U.S. wargames from suggesting an easy victory (even with the inclusion of platforms like the B-21 or NGAD in the simulation).

A kind of conventional computational deterence.
Click to expand...
J-20 is already more than enough for the role you're describing. The J-36 just takes everything it does a couple of steps further to adapt to how the competition has evolved over time, and its design screams broadband VLO to unbiased audiences...

We've known for a while that the J-20 is overall competitive in range, stealth, and sensor capabilities with every fighter the American side currently has in its arsenal. Hence the need for the longer-ranged and more revolutionary F/A-XX and NGAD designs...
 
snne said:
We've known for a while that the J-20 is overall competitive in range, stealth, and sensor capabilities with every fighter the American side currently has in its arsenal. Hence the need for the longer-ranged and more revolutionary F/A-XX and NGAD designs...
Click to expand...
When and how did we know that?

I think on stealth, that hasn't been established at all, and sensor capabilities are likewise unproven. F-22 can be significantly superior to J-20 in stealth (e,g. in specific directions or radar bands) without affecting the argument for NGAD.
 
overscan (PaulMM) said:
When and how did we know that?

I think on stealth, that hasn't been established at all, and sensor capabilities are likewise unproven. F-22 can be significantly superior to J-20 in stealth (e,g. in specific directions or radar bands) without affecting the argument for NGAD.
Click to expand...
We don't know much information so we can't take anything from the Chinese side. However we can take reports from the American side, and you could make the argument that they are merely trying to ask for more budget allocation, which is why they talk up the J-20 capabilities, but it doesn't mean they are lying either. Previously USAF generals have said that early block 20 F22's are not competitive with the J-20, and aggressor squadrons have been made with early production f-35's to simulate the stealth characteristics of the J-20. What we can take from these reports and actions are that the J-20 in it's current state has stealth on par with early F-35's, but aren't as good as the latest versions, while it's sensors and capabilities surpass early F-22's, and therefore are able to compete with block 30/35 f-22's. It doesn't mean they are better than the latest upgrades of the the F22 and F-35, but they have the capacity to compete, which should be highlighted. Just the mere capacity to compete is enough to compel the existence for NGAD.

The USAF wants to fight an air war in which it has complete overmatch in technology, an adversary that could possibly compete with it is already a threat to it's air dominance.
 
Previously USAF generals have said that early block 20 F22's are not competitive with the J-20
Click to expand...
Where? Not read that.
and aggressor squadrons have been made with early production f-35's to simulate the stealth characteristics of the J-20.
Click to expand...
That would mean its stealth capability is closer to F-35 than an F-15 or F-16 for aggressor purposes. Which I would expect. That doesn't mean the stealth is truly competitive.

To be clear, I'm not saying it isn't, but this isn't good evidence. It only has to approach the US capability to be a good argument for NGAD.
 
Last edited:
overscan (PaulMM) said:
Where? Not read that.

That would mean its stealth capability is closer to F-35 than an F-15 or F-16 for aggressor purposes. Which I would expect. That doesn't mean the stealth is competitive.
Click to expand...
www.airandspaceforces.com

Moore: ‘It’s Time to Move On’ from Block 20 F-22s, JATM Still on Schedule

The Air Force needs the $7 billion saved by retiring 32 Block 20 F-22s for the NGAD sixth-gen fighter system, the service's top planner said.
www.airandspaceforces.com www.airandspaceforces.com
In March 29 testimony before the House Armed Services Committee’s tactical aviation panel, Moore said the Block 20s are not “competitive” with the latest Chinese J-20 stealth fighters. And while the aircraft could be used for training, Moore said they are so out of synch with the combat-coded Block 35s that pilots are receiving “negative” training from them, meaning they have to “unlearn” habits developed in the Block 20 before they can become proficient in the Block 35.
Click to expand...
 
overscan (PaulMM) said:
Where? Not read that.

That would mean its stealth capability is closer to F-35 than an F-15 or F-16 for aggressor purposes. Which I would expect. That doesn't mean the stealth is competitive.
Click to expand...
Given sources of extensive frequency modeling on the internet, I'd say it's a given that J-20's VLO characteristics is within the same order of magnitude as the F-35. Of course these are not official papers from either manufacturers, and are online analysts. However much that may disprove their accuracy, the simulations are rigorous, and can show the broader picture. If civilian simulations done by experts cannot qualify in for getting a better scope on capabilities, nothing ever will until all documents pertaining to the fighter jets on either side become completely declassified.

A Preliminary Assessment of Specular Radar Cross Section Performance in the Chengdu J-20 Prototype

APA Analysis Paper APA-2011-03; Title: A Preliminary Assessment of Specular Radar Cross Section Performance in the Chengdu J-20 Prototype; Abstract: This study has explored the specular Radar Cross Section of the Chengdu J-20 prototype aircraft shaping design. Simulations using a Physical Optics...
www.ausairpower.net

Stealthflankers sim.
basicsaboutaerodynamicsandavionics.wordpress.com

F-35 vs J-20 vs Su-57 Summary

Introduction Previously, we have done HFSS simulation to evaluate the mean and median radar cross section as well as the radar scattering pattern of the four common stealth fighters namely F-35A, S…
basicsaboutaerodynamicsandavionics.wordpress.com basicsaboutaerodynamicsandavionics.wordpress.com

The F-35 does have superior stealth which is not surprising, but the J-20 does appear to be competitive in the sense where it can keep up. I'm not sure what you mean by competitive, if it means matching the F-35 in all capabilities and stealth that is not what I mean.

That is the kind of competitiveness that the USAF does not want to deal with.
 
Tomboy said:
Also the article is written in 2023, but now in 2025 there are the even newer J-20As with WS-15 entering service with upgraded sensors and stealth.
Click to expand...

To be fair weapon also factored into this. One key point is that Block 20 can’t use AIM-120D whereas J-20 could use PL-15 and later.

www.airandspaceforces.com

Keeping the F-22 Credible Through 2030 Will Cost At Least $9 Billion, USAF Leaders Say

The Air Force wants $9 billion to keep the F-22 until the NGAD is ready, but that plan depends on Congress letting 32 Raptors retire.
www.airandspaceforces.com www.airandspaceforces.com

“Upgrading the Block 20s to a combat configuration is cost-prohibitive and very time intensive,” Moore testified. “Based on the most advanced weapons that an F-22 Block 20 can carry now, it is not competitive with the [Shenyang] J-20, with the most advanced weapons the Chinese can put on it.”
Click to expand...
 
Tomboy said:
Also the article is written in 2023, but now in 2025 there are the even newer J-20As with WS-15 entering service with upgraded sensors and stealth.
Click to expand...

Credible individuals from the Chinese language side have stated that even existing WS-10 powered J-20s have seen meaningful improvements between successive production batches, in terms of signature reduction due to improvements in materials, and also improvements in overall capability due to subsystem refreshes.
Someone I've talked to who's in the know on these things from the US side have also corroborated this.
 
This is a specific statement about the Block 20 F-22, which is not fully combat capable. Even then the statement is

"Based on the most advanced weapon that an F-22 block 20 can carry now, it is not competitive with the J-20 with the most advanced weapons the Chinese can put on it."
Click to expand...
Nothing here speaks to the relative quality of avionics, stealth, or range. Specifically, it says that the Block 20 F-22 can't use modern long range AAMs whereas the J-20 can.

Not sure you can leverage this into a statement about J-20 being 'overall competitive in range, stealth, and sensor capabilities'.

Nx4eu said:
Given sources of extensive frequency modeling on the internet
Click to expand...

Please. These only give you a rough idea of 'relative' stealthiness of the basic layout. It can tell you broadly where the big spikes are likely to be, whether it is all-aspect stealthy or front quarter only.

Without accurate modelling of the shape (exactly where does one get a high fidelity model of the J-20 from?) and knowledge of the radar absorbent structures and materials it is never going to give a realistic RCS prediction.
 
overscan (PaulMM) said:
This is a specific statement about the Block 20 F-22, which is not fully combat capable. Even then the statement is


Nothing here speaks to the relative quality of avionics, stealth, or range. Specifically, it says that the Block 20 F-22 can't use modern long range AAMs whereas the J-20 can.

Not sure you can leverage this into a statement about J-20 being 'overall competitive in range, stealth, and sensor capabilities'.



Please. These only give you a rough idea of 'relative' stealthiness of the basic layout. It can tell you broadly where the big spikes are likely to be, whether it is all-aspect stealthy or front quarter only.

Without accurate modelling of the shape (exactly where does one get a high fidelity model of the J-20 from?) and knowledge of the radar absorbent structures and materials it is never going to give a realistic RCS prediction.
Click to expand...
Well then I guess the J-20 isn't competitive to American fighters after all.

Alright time to pack it in boys, due to lack of official information nothing can be inferred or extrapolated from publicly gathered information. For all we know the J-20 could be a flying piece of cardboard with no radar installed and flown by two blokes in the engines farting the thrust required to fly, nothing to see here, no one can compete with the USAF. No need to discuss a 6th generation fighter here either, none of it's systems or capabilities will be revealed to the public for the next 50 years, seeing as we still lack the sensor capabilities of the J-20, and will probably never know after the J-20 even retires.

American air dominance is completely secured for the next millennium hurrah!!

Based on the zero official information we've got on the J-20, I guess we can't even be sure if it is at all competitive with the F-15 or the F-16. I suppose the J-20 might as well be a 2rd generation jet fighter, with engines that have a overhaul lifetime of 2 hours? That's because we lack officially released data reporting the current reliability of Chinese engines. Nothing can be leveraged, no statement on the J-20 could be true, it's all made up speculation Afterall.

Man, all the talks around Chinese equipment is speculation at this point, Afterall the Chinese could just be faking their data on the things they do publicly release right? I don't see the point in discussing about Chinese equipment if all we ever can talk about is the rough idea as nothing concrete really exists. Is this the conclusion you want?

There is nothing that can reliably prove that any modern weaponry made in China can compete with American weaponry, or works as intended.
 
Last edited:
As a side note, how do we know how competitive the F-22 and the F-35 is to the J-20, if those aircraft have many things that are classified as well. Such an example like stealth, as you said, publicly available information can only tell us the
overscan (PaulMM) said:
rough idea of 'relative' stealthiness of the basic layout. It can tell you broadly where the big spikes are likely to be, whether it is all-aspect stealthy or front quarter only.
Click to expand...

We don't know the composition of the radar absorbent structures and materials of the F-35, F-22 or the J-20 right? How can you be so sure that they are definitively superior to that of the J-20? Is it just an assumption that due to American tech being more mature, it is likely to be more advanced compared to the Chinese counterpart? That isn't something that can be definitively proven either right? Just speculation.

How do you know that the J-20 isn't competitive to the F-22? We tried to prove that it is, and well, I can see it has failed. Now show us all the real confirmed classified documents that definitively prove that one highly classified system is superior to another even more highly classified system.

How are you sure that NGAD's development was not due to the rise of foreign powers, the USAF has enjoyed air supremacy for over half a century now, If China still was only flying J-7's, and Su-57 production stayed in the low 10's. Would the USAF even pursue a replacement for the F-22 that had much greater range and even more powerful capabilities (and far more expensive)? If the J-20's capabilities were so vastly inferior to the F-22, that it wouldn't perform any better against the F-22 than say a J-10 or J-7, would the USAF ever think of developing a newer more expensive fighter that was even more advanced, and primed for the pacific theater? If I may, I Infer that the J-20 isn't a reskinned J-10, was made 2 decades after the F-22 and was made to "Compete" to a certain degree, such that it poses a great enough threat to America's complete air supremacy doctrine over the pacific, that further influenced the need for a new air superiority fighter aircraft. That isn't such a big leap in logic is it ... ?

Boy am I going to wake up tomorrow to see such kind and wonderful responses from the loveliest people in the world here, aren't I.
 
Last edited:
Wonderful strawman arguments you have there, @Nx4eu, watch out they don't blow away in a light breeze. I get this is the discussion and speculation topic but still -

We've known for a while that the J-20 is overall competitive in range, stealth, and sensor capabilities with every fighter the American side currently has in its arsenal. Hence the need for the longer-ranged and more revolutionary F/A-XX and NGAD designs...
Click to expand...

China did an excellent job with speedy development of the J-20 ahead of Western estimates. The weaponry and avionics look good on paper. China does, however, lack experience in warfare and active use of their equipment in real world engagements.

Low probability of intercept radar design is complex, and algorithms for TWS, NTCR, ECCM etc are closely guarded secrets and evolved and refined in the US (and UK, France..) over many years and generations of radar designs. Counting the number of AESA elements, or reading placard range on a radar display at Zhuhai, doesn't speak to these essential characteristics, so its hard to conclude the J-20 is competitive. Maybe China will hit it out the park on first try, but history suggests real world experience is a great teacher.

Additionally, they have had challenges getting up to speed with engine development, and J-20 still hasn't reached parity in this area. As @F119Doctor has noted in other topics, supercruise requires a specifically optimised engine design. WS-15 may be such an engine. WS-10 is not. We don't at this stage know how much fuel the J-20 carries, so its hard to be certain of its range. We can make estimates, but we don't know.

Rough RCS analysis tools such as we have show J-35 does not appear to be shaped with all-aspect VLO in mind. The basic configuration is not optimal for stealth, and there's only so much you can do with materials. It is likely the stealth requirements for J-20 were notably lesser than F-22, especially in the side and rear aspect.

It's still likely that its better in this respect than any fighter in service outside F-22 and F-35. But that doesn't mean we can conclude its 'competitive in stealth' with the F-22, which seems to be your conclusion.

When you make statements like

We've known for a while that the J-20 is overall competitive in range, stealth, and sensor capabilities with every fighter the American side currently has in its arsenal.
Click to expand...

it comes across a bit "China Stronk". If you want sound more credible, cite the sources that lead you to this opinion. The specific source cited above is much more about redirecting Congress from funding costly upgrades to near-obsolete early F-22 Blocks to spending in more useful areas than anything else.

US Air Force sources have generally been surprised by the rapid pace of China's developments, but still reasonably confident an American pilot in the F-22 Block 35 could still handle the J-20. However the margin of superiority has been significantly eroded and this is a pretty awesome achievement for China.

Back to topic....

The J-36 represents a possible turning point here, and the USAF needs to pick a path forward pretty soon or get left behind.
 
Last edited:
stealthflanker said:
Well mine was from the other thread discussion, which 23 m in length and 19 m in wingspan. It's from the exchange of Flateric and you i think.
Click to expand...
Thanks for the info!
My current (revised) model is 21.5m long and has a wingspan of 22m. I've overlapped CAD-screenshots with available photos to check proportions. The result isn't 100% satisfactory, but I'm not all too far off.
On another note, RAeS ( @LowObservable ) came up with 22.5m × 19.8m. It will be interesting to see who was closest once official specs are available ;)
 
It's really a pointless argument. Given that there is currently no air war between two countries between fifth-generation aircraft, I think that all arguments are untenable, in a Chinese idiom is "纸上谈兵", it is better for both sides to sit down and drink something, after all, we are not politicians or enemies, just aircraft enthusiasts.
 
overscan (PaulMM) said:
This is a specific statement about the Block 20 F-22, which is not fully combat capable. Even then the statement is


Nothing here speaks to the relative quality of avionics, stealth, or range. Specifically, it says that the Block 20 F-22 can't use modern long range AAMs whereas the J-20 can.

Not sure you can leverage this into a statement about J-20 being 'overall competitive in range, stealth, and sensor capabilities'.
Click to expand...

Well, I hate to be the “to be fair guy” but J-16 and J-10C could carry the PL-15 as well and J-16 can even carry the PL-17. If it is just about weapons carried you can arguably say that Block 20 is not competitive with J-16 either. What we can conclude from Moore’s assertion is that block 20 + AIM-120C is not competitive with J-20 + PL-15/16.
 

Similar threads

Please donate to support the forum.

Back
Top Bottom