Chengdu J-20 news and analysis Part III

That's just a WS-10 with a Chinese copy of the LOAN nozzle. There is literally zero credible proof to substantiate the PLAAF flying J-20s equipped with WS-15s. No, CCP controlled state media tasked with external propaganda efforts isn't proof. Especially when that proof is from some blurry, grainy pic taken from half a mile away, and "leaked" by totally not Chinese intel/SCIO. Can anyone show me a close up of a WS-15 core, and then show a close up of that WS-15 in a J-20? So far, everything points to the engines being WS-10b/c with a Chinese copy of the LOAN nozzle.
 
Deino said:
Allegedly a video of no. 2052's maiden flight ... I'm still not convinced, but what I find interesting is, when I saw that video it was one of my first impressions, the sound is different to a WS-10C, more of a dull, deep rumble.
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First of all: I enjoy your work, and dedication. My only concern is that you're being used by the MSS/SSSB/SCIO to push and spread their propaganda to Western audiences. You seem to take what the CCP/PLAAF, or some totally not Chinese intel setting at the end of a runway monitored 24/7 by CCTV with facial recognition, at face value. It's not like the CCP/state police don't know someone is at the airfield taking pictures of their 'secret' fighter that "owns the West." If they didn't want you to see it, you wouldn't, and that person taking those pics would be gulag'd before being able to upload said pics. Don't take what I say personally, it's just a major concern with Chinese information, the same as it was with the USSR during the Cold War. Also, whose's to say the PLAAF isn't taking a page from their old Soviet playbook and renumbering their J-20s to make it seems as though they have many more built and fielded than they actually do? The CCP lies about literally everything else, and have been caught many times providing false import/export numbers, GDP figures, populations/demographic figures, poverty figures, etc. Why would I take their word as truth, and their claims at face value, when all evidence points to their default response is to lie? Again, I enjoy your work and dedication, though I think you're a little naive when it comes to your trust in information coming out of China.
 
I disagree with you about @Deino, I think he is fairly conservative with taking anything at face value and tries to corroborate all information. In fact, he is being sceptical in the very post you quote.

Also, whose's to say the PLAAF isn't taking a page from their old Soviet playbook and renumbering their J-20s to make it seems as though they have many more built and fielded than they actually do?
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Well, there are a lot of satellite photos from commercial providers providing evidence. I'm not sure its evident why China couldn't be building a lot of them if they want to, that seems more like wishful thinking on your part than @Deino
 
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activeaero said:
Deino said:
Allegedly a video of no. 2052's maiden flight ... I'm still not convinced, but what I find interesting is, when I saw that video it was one of my first impressions, the sound is different to a WS-10C, more of a dull, deep rumble.
Click to expand...

First of all: I enjoy your work, and dedication. My only concern is that you're being used by the MSS/SSSB/SCIO to push and spread their propaganda to Western audiences. You seem to take what the CCP/PLAAF, or some totally not Chinese intel setting at the end of a runway monitored 24/7 by CCTV with facial recognition, at face value. It's not like the CCP/state police don't know someone is at the airfield taking pictures of their 'secret' fighter that "owns the West." If they didn't want you to see it, you wouldn't, and that person taking those pics would be gulag'd before being able to upload said pics. Don't take what I say personally, it's just a major concern with Chinese information, the same as it was with the USSR during the Cold War. Also, whose's to say the PLAAF isn't taking a page from their old Soviet playbook and renumbering their J-20s to make it seems as though they have many more built and fielded than they actually do? The CCP lies about literally everything else, and have been caught many times providing false import/export numbers, GDP figures, populations/demographic figures, poverty figures, etc. Why would I take their word as truth, and their claims at face value, when all evidence points to their default response is to lie? Again, I enjoy your work and dedication, though I think you're a little naive when it comes to your trust in information coming out of China.
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Only having distrust and dislike of China and/or CPC is not enough to nullify or argue against years of PLA watching experience and track record.

Provide the receipts.


If anything, inherent distrust and dislike of China and the CPC probably makes one less able to be a competent PLA watcher. Having a degree of indifference and non-hostility OTOH are more useful baseline traits.
 
I take it the RCS calculations must not take into account RAM, because 0.2m^2 frontal RCS seems high for a stealth aircraft?
 
I think one of the big fears with canards is if they move during course adjustments... that can produce temporary signature increases... even worse is if they are permanently deflected in order to provide trim. This problem is reduced if one has 3d thrust vectoring though, as that can replace conventional control surface movements.

However, the issue still exists if the control surfaces are angled as a result of how the aircraft is trimmed. I suspect a conventional design might allow a bit more masking of the stabilisers when flying head-on... but if the opponent isn't flying straight head-on... it could still be an issue? I suspect that the canards aren't that much of an issue.

I would be curious to see simulations/estimates based on the presence or absence of the ventral strakes though!
 
Forest Green said:
I take it the RCS calculations must not take into account RAM, because 0.2m^2 frontal RCS seems high for a stealth aircraft?
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I mentioned it in the tweets, the airplanes are PEC. that's perfect electric conductor.

Avimimus said:
I think one of the big fears with canards is if they move during course adjustments... that can produce temporary signature increases... even worse is if they are permanently deflected in order to provide trim. This problem is reduced if one has 3d thrust vectoring though, as that can replace conventional control surface movements.
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This has to be defined statistically, which is beyond the simple depictions i provided, considering that the aircraft may or may not require canard deflections in its entire flight or whether the strongest specular lobe would always be in view to hostile radar. The measurement or simulation would probably also needs to be dynamic, which unfortunately ANSYS plugin "move-it" which could do is No longer supported in the version i have and they already removed it from the shop.

Avimimus said:
I would be curious to see simulations/estimates based on the presence or absence of the ventral strakes though!
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As much as i want to do it... i am a mere human, and a human cannot move without food and i'm all out of food right now.
 
In_A_Dream said:
China increases J-20 stealth fighter jet production




I wonder what the "strong impression" was?
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The encounter was quite a while ago (March of 2022 specifically) so there's some articles from around then that have more context on what Wilsbach said about not only the J-20 but also of KJ-500 AEW&C aircraft:
https://www.eurasiantimes.com/chinese-j-20-meets-us-f-35-stealth-fighter-jet-for-the-first-time/
 
icyplanetnhc (Steve) said:
Any time someone cites EurAsian Times, your divinity of choice murders a kitten or puppy.
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Take your pick:

1691944032024.jpeg 1691944091410.png

In all seriousness though does anyone have the original response from General Kenneth Wilsbach's report on the incident?
I would like to know what he fully said and that would probably provide better first hand information than major news outlets' 15% reporting, 85% analysis.

Thanks
HalfACupOfRice
 
HalfACupOfRice said:
In all seriousness though does anyone have the original response from General Kenneth Wilsbach's report on the incident?
I would like to know what he fully said and that would probably provide better first hand information than major news outlets' 15% reporting, 85% analysis.
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Here is what Gen. Wilsbach stated originally in an Aerospace Nation event hosted by the Mitchell Institute for Aerospace Studies on March 14, 2022.

View: https://youtu.be/GNPo6S5uwZQ?t=2845
 
More into Canard.

So recently i did a little study which involves attempt of animating the canard in Ansys and trying to visualize how the canard's "mainlobe" or spikes behave during canard movements.


The movement are 0-35 degrees with additional 60 degrees to illustrate "extreme angle". The J-20 model is the same as what i use previously here, no absorber except in inlet, that's because applying the absorber in the aircraft are hell due to so many surfaces and i got demotivated by Ansys which is not as versatile as Blender in selecting multiple faces.

The purpose of this study is of course to observe the behavior and influence of Canard movement to RCS. Anyway the result. as follows.


This example is in X-band (10 GHz) One can easily notice the "strong" reflection of the canard started to appear at 15-20 degres deflection and become more visible as the deflection increases. At 60 degrees, the reflection formed some unique pattern.

Numerical wise however, the behavior of the canard is gradual but not exactly linear, in the manner that in some frequencies the RCS are lower compared to the canard at 0 degrees incident.

GraphREsult1.png

Also included comparison with other aircrafts. One can easily notice that the most noticeable increase are in low band (VHF, L) The increase of RCS also not "dramatic" as some social media accounts make out of it (e.g it forms corner reflector, canard= large RCS) At least in high frequency and low deflection below 20 degrees, the increase of RCS are apparently small.

The following depict the increase or decrease of RCS in percentage and broken down into frequencies

Graph Result-2.png


Notice that in small deflection angles, the increase in RCS are relatively negligible. Only when the canard is deflected to 20 degrees or more, the strong reflection start to affect the RCS into more linear fashion. The following is the table form of the graphics above

Table1-Breakdown.png

The negative sign in some frequencies is yes, depict that the RCS on that deflection angle and that frequency is smaller compared to the canard in normal angle. On subject of why. i wonder. Especially it's not in all frequencies, resonance maybe or there is certain contributor parts that got obscured by the canard movement and therefore not visible within the simulated angle. The next table depicts the averaged value of all frequencies.

Table2Average.png

One may easily notice that at least until 20 degrees. the "increase" of RCS are relatively negligible. While for larger angle, the increase become more noticeable.

It is however can be questioned, what angle the J-20 canard will realistically be employed. Is deflection beyond say 10 degrees are necessary during flight operations ?
 
interesting results, so the more the canards turn, the more impact it has on RCS, which makes sense.

have you done something similar on the moving tail/rudder, since the J-20's can entirely move?
it seems more designs will adopting this type of tail too. wondering how it affects RCS
 
helmutkohl said:
have you done something similar on the moving tail/rudder, since the J-20's can entirely move?
it seems more designs will adopting this type of tail too. wondering how it affects RCS
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Nope, will only do so if commissioned or when i feel like it.

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I really wonder, what kind of RCS people expect to see from canard. i have seen many people seems to view canard like some sort of horror for a stealth aircraft.
 
So long as the canard remains aligned to the main wing, its additional RCS is mostly negligible as it is lost in the wing return. However, as it deflects it stops being aligned to the wing. You could program the FCS with restrictions on deflection angles I suppose.

Given a fighter's frontal RCS is generally the most important, having a rear tail is easier to design for stealth.
 
stealthflanker said:
Nope, will only do so if commissioned or when i feel like it.

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I really wonder, what kind of RCS people expect to see from canard. i have seen many people seems to view canard like some sort of horror for a stealth aircraft.
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In fact, watching the flight video, it seems that the canard rarely moves or even does not move, which means that the full-motion canard can achieve the required control effect with very little deflection.
 

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