J-20 5th Gen Fighter Thread VI

[Quickie]

Interesting magazine on testpilot He Bingbing, who test flew the J-20 and JF-17.

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The most interesting takeaway from the article was that a "new fighter" (likely J-20 because the JF-17 caps out Mach 1.6) achieved the fastest speed for a domestically produced fighter during test flight.

I think J-8 should have the fastest speed before that.

 

[Hyperwarp]

Interesting magazine on testpilot He Bingbing, who test flew the J-20 and JF-17.

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The most interesting takeaway from the article was that a "new fighter" (likely J-20 because the JF-17 caps out Mach 1.6) achieved the fastest speed for a domestically produced fighter during test flight.

J-8II - Mach 2.2
J-10/10A - Mach 2.2 (J-10B/C with the modified intake has a slower top speed)

So, J-20 Mach 2.2+ ???

 

[Air Force Brat]

Metamaterials was first brought to the public domain when in 2006 John Pendry of Imperial College published two papers showing how to create a Harry Potter-style invisibility cloak using the specially engineered materials. David Smith, professor of electrical and computer engineering at Duke University, who was a co-author of the research, went on to produce the first functioning cloak — although it made objects invisible to microwaves rather than to visible light.

Since then several companies have commercialised metamaterials, including Kymeta Corporation which sells satellite antennas made from metamaterials and Echodyne, which makes radar for drones.
View attachment 53067
Currently shaping accounts for 90% of the radar cross-section (RCS) reduction of a stealth aircraft and RAM the remaining 10%. And where RAM might reduce RCS by an order of magnitude, shaping can shrink it by three or four orders. But RAM reduces radar returns from certain features more than these guidelines imply and, while progress in shaping may be plateauing, in materials it is advancing rapidly. Lockheed is a major investor in metamaterials. The problem is how to sensibly apply the technology.

The following best sum up the problem “One might be tempted to construct an aircraft skin from such “transparent” materials, but radar would then reflect off objects beneath the surface such as sensors, fuel, metallic airframe and engine parts and the pilot. In practice, the bottom layer of a stealth skin is a highly conductive material, such as metal, which strongly reflects radar waves before they reach the complex reflecting environment below.” There is a reason why the membrane are selectively applied to the trailing and leading edges.

Source : AWST - The ‘Magic’ Behind Radar-Absorbing Materials For Stealthy Aircraft
View attachment 53068

So here you go, this is not new technology, but it is no doubt being continuously refined, and new applications introduced.....
so while its apparently being applied in certain areas of 4 Gen aircraft, its an absolute necessity for 5 Gen applications, but is of highly secondary importance to shaping. The reason the J-20 is likely very L/O and the Su-57 is dicey at best, relaying on meta-materials/RAM to reduce RCS.

 

[Air Force Brat]

Every picture of serials he has either comes from official state media or events so public like the Zhuhai airshows that it's almost as ridiculous as proposing the J-20 doesn't have an operational radar to imagine the PLA cares about the serials revealed.

I'm rather certain that Siege is indeed correct, listing serials in order to display numbers and locations of aircraft produced would no doubt be frowned upon, depending on "who" you are, and what your intention in revealing same might be...

you might get invited for tea? particularly now, when these articles have once again become sensitive material, so from the looks of things, we are still hovering around 20 airworthy airframes for test and in active duty squadrons... as Deino has suggested hopefully new airframes are being built with indigenous WS-10s finally..

It has indeed been a long while since we have seen any "primer birds" making first flights, though that is now no doubt sensitive material as well??

so for all we know, the PLAAF may have 35 to 40 aircraft? but I remain extremely skeptical of that? but I've been surprised before, by both good and bad news?

 

[Equation]

J-8II - Mach 2.2
J-10/10A - Mach 2.2 (J-10B/C with the modified intake has a slower top speed)

So, J-20 Mach 2.2+ ???

Not that Wikipedia is a very reliable source, it lists J-8IIM at Mach 2.4 (with 2.2 limit), J-11A at Mach 2.35, and J-15 at Mach 2.4. I think the J-11A figure is most reliable since that is what's known for Su-27SK.

 

[Equation]

So here you go, this is not new technology, but it is no doubt being continuously refined, and new applications introduced.....
so while its apparently being applied in certain areas of 4 Gen aircraft, its an absolute necessity for 5 Gen applications, but is of highly secondary importance to shaping. The reason the J-20 is likely very L/O and the Su-57 is dicey at best, relaying on meta-materials/RAM to reduce RCS.

Meta-materials is not new technology. The advances they made on top of what they had in the field of meta-materials (likely what was applied to J-20) is the new technology potential that the article was talking about.

 

[taxiya]

Fair enough, since that is kind of my point also. Where we diverge is that as far as *I* can tell there is by no means any consensus on a definition among researchers either, so it's difficult to even appeal to authority on this subject. Here's a good primer:

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In fact, entire papers are devoted solely to the question of nailing down what exactly should be considered a metamaterial:

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The bottom line is that in my opinion it is a bit useless to even discuss metamaterials without more detailed specifics on what type is being applied. If even the experts can't agree on what "metamaterial" means, it should not be used like a well-established scientific term - it's best considered a buzz word that requires more context for proper appreciation of its significance. Does the J-20 really do something new or is there a precedent after all? It's impossible to tell merely based on it being described as a metamaterial.

1. The essence of those technologies is the most interested subjects to discuss. I think we all agree on that.
2. The naming "what is and which is metamaterial" is our difference (divergence). It is not an issue for me which got the fancy name, but it is important to give a name to differentiate them (F-35 type of composite vs. PCB like later material) when having a discussion without confusion. For that purpose, I have chosen what have read, while you provided the links.
3. Regarding your evidence, can you provide publications prior to F-35 type composite introduction that actually used the word "metamaterial" to refer to what F-35 is going to use? The link is a retro-application of the word "metamaterial" back to early researches. It is not really about consensus (everyone agrees), not necessary either, it is about who and when it began to be used for exactly what. The publications that I read which used metamaterial were all about the PCB like.
   1. The first link is the metamaterial that I was talking about which was in experiment in 2001 some time after F-35 program started. Can you say this type was used by F-35? This link actually strengthens my defination.
      
      
      
   2. The second link is a PERSONAL view by the author in 2009, far after F-35 into its development. It is a retro-application of the name metamaterial like today's renaming everything trend.
4. I know you object my exclusive usage of metamaterial on the PCB like ones excluding the F-35 type, and I am willing to loosen that usage, but as I said in point 2 we need non confusing names. What would you suggest to use then? So when people talk about F-35 and J-20 use something, we can make sure that we MAY be talking about different things.
5. My point general point is that it is important NOT to re-apply some future name back to earlier things to make a big confusion, EVEN IF that name is not accepted in all corners.

You are welcome to add on, while I think I must stop now hoping I have made myself clear.

 

[jobjed]

IMO the PLA cares about serials being revealed in some cases. There have been official photos of aircraft in units where the serials have been deliberately edited out, and of course it's normal for plane spotters to edit out serials of aircraft in service as well in their pictures.

And I think that is quite sensible, because sometimes serials for certain types of aircraft can provide valuable intelligence, such as where aircraft are based, the number of aircraft in said unit etc.


In this case, the photo revealed very little because we've known for a while that 9th brigade has had J-20s, and this aircraft #62001 is literally unit "01" of 9th brigade, which only in theory allows us to "confirm" that "only one" J-20 is in 9th brigade, even though we can be very confident that it's almost certainly more.



I.e.: the PLA does care about serials, but when they release pictures where the serial is visible it likely means that they made a deliberate, conscious choice to allow that serial to be shown (likely because it is no longer deemed worthy of opsec)

I said it's ridiculous the PLA would care about serials revealed at public events like Zhuhai. I didn't say they don't care about serials as a general rule.

 

[Hyperwarp]

Not that Wikipedia is a very reliable source, it lists J-8IIM at Mach 2.4 (with 2.2 limit), J-11A at Mach 2.35, and J-15 at Mach 2.4. I think the J-11A figure is most reliable since that is what's known for Su-27SK.

siegecrossbow said "domestically produced fighter". J-11A is a licensed build fighter where the kits are imported from Russia. That's why I excluded it. If we include the J-11A, then the Mach 2.35 is the best value since that value applies to the Su-27SK as well. Wiki entry for the J-15 can be disregarded. According

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the J-15 is powered by the WS-10, which we know is not the case.

J-8II is probably the fastest locally produced fighter. The max speed of Mach 2.2 seems to be consistent across multiple sites. One issue though is, whether the original J-8 was faster than the modern J-8II. Original J-8 with the nose intake would have been lighter than the J-8II. So the Mach 2.4 value may apply to the J-8.

 

[latenlazy]

So here you go, this is not new technology, but it is no doubt being continuously refined, and new applications introduced.....
so while its apparently being applied in certain areas of 4 Gen aircraft, its an absolute necessity for 5 Gen applications, but is of highly secondary importance to shaping. The reason the J-20 is likely very L/O and the Su-57 is dicey at best, relaying on meta-materials/RAM to reduce RCS.

On the contrary, just because some piece of tech shares a broad general category with another piece of tech, that doesn’t mean that technology *isn’t* new. Diminishing one new kind of metamaterial because it falls into a pre-established category is like saying there’s nothing special about a rail gun because linear motors have been around for over 100 years.