J-20 5th Gen Fighter Thread VI

[Tirdent]

I respect your holding your disagreement, but I am not interested in continue a debate with you about the definition, because it is neither mine nor yours.

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.

 

[Air Force Brat]

Which definition would that be? A perennial problem in this discussion is that in fact no universally accepted or applicable definition of "metamaterial" exists, it's a relatively recently coined buzz word (dating to 2000 or thereabouts IIRC). Latenlazy's post offers what I'd consider a very good description, and frequency selective surfaces or integrated forebody materials as used by the Eurocanards or F-22 and F-35 meet it exactly. How do you think they achieve their bandpass properties? What do the following look like to you?

View attachment 53063
Eurofighter Typhoon FSS radome pattern

View attachment 53064
Sukhoi FSS antenna shroud pattern

Like so many buzz words, there were perfectly valid instances long before the term first appeared - take "SUV", numerous car models meeting every aspect of the definition (such as it is - there isn't really an agreed formula either) of that term were built long before it was coined by Jeep in the mid-1970s. It follows that although you won't find any sources describing the Eurofighter radome FSS as a metamaterial (simply because when it was developed in the late-1980s/early-1990s the term had yet to be invented), it doesn't mean it can't in fact be considered one. If it walks like a duck...

Exactly, it doesn't mean the Chinese are not taking it to the next level, they very well may be, but that does not negate the fact that both F-35 and F-22 are indeed using a membrane overlaid on the leading and trailing edges, imbedded with the same radar absorbing/diverting metallic RCS reduction technology....

Mr. Trident is no doubt right, that others have been using these materials as an "overlay" for a long time...

 

[localizer]

Exactly, it doesn't mean the Chinese are not taking it to the next level, they very well may be, but that does not negate the fact that both F-35 and F-22 are indeed using a membrane overlaid on the leading and trailing edges, imbedded with the same radar absorbing/diverting metallic RCS reduction technology....

Mr. Trident is no doubt right, that others have been using these materials as an "overlay" for a long time...

As a scientist I can tell you we come up with all sorts of stupid names just to amaze people when it's just an iteration of some old thing.

 

[Brumby]

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.

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

 

[siegecrossbow]

Indeed, if you want only those confirmed by imagery, then this is the best we have. Thanks to @huitong

But I have the feeling that there are already between 8-12 for the 176th and 172nd Brigades each plus at least 4-6 for the 9th Brigade... I however would like to know how many are already built altogether, how many are in preparation to delivery and at what rate they are produced.

And if possible, if the second batch will get the WS-10?

When did Huitong start adding the serial count to his website? Admittedly I haven't visited in a while.

That said, I assume Huitong is not in PRC currently? With tightened security I think he might get in trouble for disclosing serials like that.

 

[jobjed]

When did Huitong start adding the serial count to his website? Admittedly I haven't visited in a while.

That said, I assume Huitong is not in PRC currently? With tightened security I think he might get in trouble for disclosing serials like that.

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.

 

[Hyperwarp]

When did Huitong start adding the serial count to his website? Admittedly I haven't visited in a while.

That said, I assume Huitong is not in PRC currently? With tightened security I think he might get in trouble for disclosing serials like that.

Do you mean these?
If so, then his "Gallery II" contains a ton of serials -

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Plus, he adds serials in the specific blog entries for the aircrafts

He has been doing that for a very long time.

 

[ZeEa5KPul]

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.

And it can't fire missiles at supersonic speeds either, haven't you heard.

 

[Blitzo]

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.

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)

 

[siegecrossbow]

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.