J-20 5th Gen Fighter Thread VI

siegecrossbow said:

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.

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siegecrossbow said:

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.

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Brumby said:

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.
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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
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jobjed said:

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.

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Hyperwarp said:

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+ ???

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Air Force Brat said:

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.

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Tirdent said:

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.

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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.

Bltizo said:

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)

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Equation said:

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.

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Air Force Brat said:

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.

Click to expand...