J-20 5th Gen Fighter Thread VI

[SamuraiBlue]

Just take a step back and think about the principle of electro-magnetic waves and how they bounce off a surface, taking the microwave oven as an example.
You see that glass screen with a metal mesh to see inside?
The metal mesh holes are smaller than the wave length of the microwave that is generated within so the microwave does not leak out.
Basically meta-material utilizes the same principle except that the gaps of the 3D metrics are larger than the radar wave but once the radar wave enters the meta-material they are force to bounce off offset from the bottom since the bottom of the meta-material are made of continual 3D angles and again are bounce back by overhanging structures back to the basin of the meta-material forcing the radar waves to go back and forth within the meta-material 3D matrix.
Basically within a meta-material 3D matrix structure it is like a house of mirrors where radar waves are forced to move in different directions away from where it entered.

 

[Iron Man]

Just take a step back and think about the principle of electro-magnetic waves and how they bounce off a surface, taking the microwave oven as an example.
You see that glass screen with a metal mesh to see inside?
The metal mesh holes are smaller than the wave length of the microwave that is generated within so the microwave does not leak out.
Basically meta-material utilizes the same principle except that the gaps of the 3D metrics are larger than the radar wave but once the radar wave enters the meta-material they are force to bounce off offset from the bottom since the bottom of the meta-material are made of continual 3D angles and again are bounce back by overhanging structures back to the basin of the meta-material forcing the radar waves to go back and forth within the meta-material 3D matrix.
Basically within a meta-material 3D matrix structure it is like a house of mirrors where radar waves are forced to move in different directions away from where it entered.

Yes, this is how metamaterials work.

 

[plawolf]

Um, no. You could use the exact same argument to "prove" any kind of unfounded conjecture. String a couple of unrelated articles together with some random internet crap speculation, demand that evidence directly linking them is not required, make some categorically unproven statements, and voila you somehow now have access to an alleged solid J-20-prereveal type of "fact", which in reality is still just nothing but speculation hanging on the most tenuous of logical threads. And yet you have made a definitively unambiguous claim to fact, as if you were simply relating that the sun rises each day and you were merely passing this knowledge on to the rest of us.

As I said before, you need to actually look at the real world instead of demanding things anyone with even the most basic understanding how military, especially Chinese military watching, would tell you you will never get, or at best won’t get for years or even decades.

By your standards, just how much of the Chinese military can you actually prove exists? Or maybe is this not about actually trying to get the most up to date and accurate assessment and more about winning the argument and/or pride policing?

would be far better for you to directly link the articles you mentioned instead of obscuring them inside 268 pages of J-20 thread, and point out exactly in these articles where the J-20 is speculated to be currently using UHF-specific metamaterials. Current metamaterials "research" is insufficient, speculation on current metamaterials use is insufficient. What is needed is evidence that research on UHF-specific metamaterials has already been finished, along with some kind of evidence that J-20 is currently using UHF-specific metamaterials; these don't have to be present in the same article but they should both be present in some form for your claim to have any iota of legitimacy at all. Your mere personal opinion that this is the case is wholly insufficient.

It seems pretty clear you are more interested in winning the argument than you are in finding out the truth. With all the time you spend whining about me not putting everything on plate for you, you could have easily done a 5min search and found not only several articles, but pages worth of discussion.

I have already wasted too much of my time with you on this. Believe what you want, it makes absolutely no difference. Good day.

 

[Iron Man]

As I said before, you need to actually look at the real world instead of demanding things anyone with even the most basic understanding how military, especially Chinese military watching, would tell you you will never get, or at best won’t get for years or even decades.

By your standards, just how much of the Chinese military can you actually prove exists? Or maybe is this not about actually trying to get the most up to date and accurate assessment and more about winning the argument and/or pride policing?



It seems pretty clear you are more interested in winning the argument than you are in finding out the truth. With all the time you spend whining about me not putting everything on plate for you, you could have easily done a 5min search and found not only several articles, but pages worth of discussion.

I have already wasted too much of my time with you on this. Believe what you want, it makes absolutely no difference. Good day.

Thank you for confirming that you are unable to even remotely back up your claim about the J-20's alleged use of UHF-specific metamaterials, and have to resort to personal attacks to try and cloud the fact that you simply cannot provide anything useful to substantiate your claims. I have no doubt that in your view, not being interested in merely winning an argument would be to get with your program and suck up every last substanceless claim coming out of you, yes?

 

[taxiya]

So you admit to no evidence for UHF-specific metamaterials use on the J-20. Current use of metamaterials in general on the J-20 is not a topic that interests me nor was it the reason I was prompted to respond to plawolf. If you look back a few pages plawolf had been claiming that the J-20 was nigh invisible to AWACS. I had responded by saying that stealth fighters in general are not designed for UHF-band RCS reduction, and subsequently the stealth features of the J-20 are significantly attenuated against AWACS which uses the UHF band. He subsequently slipped in a comment a few pages later that the J-20 is currently using UHF-specific metamaterials, clearly an indirect response to my post. And here we are now at this juncture, with still neither of you having any tangible evidence that the J-20 is using UHF-specific metamaterials despite all the innuendo and pages of back and forth.

I never said there is evidence for UHF specific metamatria application on J-20. So not my concern to admit or reject. However, if you understand metamaterial (I repeat), UHF is nothing specific than VHF or any other frequency in metamatrial realization, you would admit that asking for UHF specific proof is a moot point to begin with. Your fixation on UHF specific proof seems to be a strawman tactic to prove other's wrong and your being right.

You honestly think I have not done my due diligence prior to posting in this thread? I have no doubt that you have also done your due diligence, but the real question is whether you really understand what you're reading and how you think any of it applies to the J-20's current use of UHF-specific metamaterials. Research papers are INSUFFICIENT in and of themselves. The ones I have seen read like feasibility studies, as in significant reductions in the thickness of UHF-specific metamaterials are possible, or even have been successfully demonstrated in the lab, and could in the future be used in real world applications. Lab work is the foundation for real world applications, but these two are not even remotely the same things. In the case of China publications on real world applications will of course not be forthcoming, in which case we would have to look at each paper and what conclusions/statements they are making about their specific contributions to eventual operational fielding of UHF-specific metamaterials, as well as the date of publication. Remember that UHF-specific metamaterials have an extra step that X-band metamaterials do NOT have, namely the requirement for size/thickness reduction. Just demonstrating that "metamaterials" research is complete or even that such materials are currently in use on the J-20 is insufficient evidence of UHF-specific metamaterials in use on the J-20. If you think any of the articles you have read constitutes "concrete evidence" of the J-20 currently using UHF-specific metamaterials, please link them here and we can discuss the merits of the papers you have linked.

And BTW, the RCS of the F-22 is quoted as being that of a metal "ball bearing" or "steel marble", not a pingpong ball, and yes, it IS conjecture and always will be.

Nobody said that lab work equate to engineering application. The discussion was always around whether China has reached engineering application on J-20, right? For that, there has been claim and News and video few months ago in this forum. So why do you still insist that proof is NOT forthcoming? What is not forthcoming is the details such as frequency bandwidth. In China's case, we are NOT talking about research papers any more. (I am repeating again).

It seems you constantly ignore the "China enters mass production of metamaterials" topics. I realize that you were not active in this forum for the last half year, so you may very well not aware of it. So please search through this Forum, there were many pages of it (again I am repeating).

Regarding F-22, I use it for the purpose of debate, details were not my interest. But thanks for the information.

 

[taxiya]

Just take a step back and think about the principle of electro-magnetic waves and how they bounce off a surface, taking the microwave oven as an example.
You see that glass screen with a metal mesh to see inside?
The metal mesh holes are smaller than the wave length of the microwave that is generated within so the microwave does not leak out.
Basically meta-material utilizes the same principle except that the gaps of the 3D metrics are larger than the radar wave but once the radar wave enters the meta-material they are force to bounce off offset from the bottom since the bottom of the meta-material are made of continual 3D angles and again are bounce back by overhanging structures back to the basin of the meta-material forcing the radar waves to go back and forth within the meta-material 3D matrix.
Basically within a meta-material 3D matrix structure it is like a house of mirrors where radar waves are forced to move in different directions away from where it entered.

That is one part of metamaterial. The other part as I read is capacitors fabricated on the sheet. If the 3D matrix is seen as wave-guide and micro antennas, the capacitors can be seen as tuners in a radio receiver which set the receiving bandwidth to a range rather than a point. There are more things metamaterial can do, it is essentially a PCB with micro antennas, inductors and capacitors (so far today), and even (in the future) micro transistors to do more things.

 

[Iron Man]

I never said there is evidence for UHF specific metamatria application on J-20. So not my concern to admit or reject. However, if you understand metamaterial (I repeat), UHF is nothing specific than VHF or any other frequency in metamatrial realization, you would admit that asking for UHF specific proof is a moot point to begin with. Your fixation on UHF specific proof seems to be a strawman tactic to prove other's wrong and your being right.

Wow. Just wow. I just posted for you the entire sequence of post and repost between myself and plawolf and you have decided to completely ignore this series of posts, and are now calling the entire purpose of the debate between myself and plawolf a "moot point". No, tough guy, it is not a "moot point". It is the ENTIRE POINT. UHF band is NOT a band that is a focus of stealth technologies for use on fighters, which are invariably tuned to maximally attenuate against high frequency bands like X and Ka, the bands that fighter and missile radars typically use, and to a lesser extent C and S bands, the bands that MFRs typically use. IIRC the F-35's skin even has some effectiveness against L band. But UHF and VHF bands? Name me one other fighter whose stealth features have been specifically designed to defeat these bands. That is why UHF-specific metamaterials use on stealth fighters are a big deal, because this goes against established practice. I'm not saying this means that it is impossible that stealth fighters in the future will use UHF-attenuating technologies, but certainly the bar is higher and you DON'T get to use sloppy logic to try and win points here. What it also means is that the J-20 currently remains vulnerable to detection by AEW&C aircraft that transmit in UHF and VHF bands, i.e. planes like the AWACS, and by surface radars that transmit in those bands. It is the same principle that Chinese "anti-stealth" radars use to detect fighters like the F-22 and F-35.

And you are dead wrong about UHF/VHF vs other frequency bands as far as metamaterials are concerned. What this tells me is that you are either deliberately ignoring the physics or you don't even know the physics and you didn't actually do your due diligence. The lower the frequency band you are trying to defeat, the larger/thicker your metamaterial needs to be, which is obviously a problem as far as aerospace applications are concerned. Here is an article from last year describing a potential solution for this problem (for a VHF-specific ultra-thin metamaterial):

Please, Log in or Register to view URLs content!

And another one from 2015:

Please, Log in or Register to view URLs content!

Neither of them mention any degree of readiness for real world application. In fact the second citation notes a thickness achieved of 7.8mm. That's three quarters of a cm. Imagine that on the skin of a fighter when traditional RAM coatings are massively thinner.

Nobody said that lab work equate to engineering application. The discussion was always around whether China has reached engineering application on J-20, right? For that, there has been claim and News and video few months ago in this forum. So why do you still insist that proof is NOT forthcoming? What is not forthcoming is the details such as frequency bandwidth. In China's case, we are NOT talking about research papers any more. (I am repeating again).

It seems you constantly ignore the "China enters mass production of metamaterials" topics. I realize that you were not active in this forum for the last half year, so you may very well not aware of it. So please search through this Forum, there were many pages of it (again I am repeating).

Regarding F-22, I use it for the purpose of debate, details were not my interest. But thanks for the information.

Again, I have ALREADY told you before, that I am NOT concerned about the use of metamaterials in general on the J-20 and never was. If you think I was then link and post where I said that metamaterials absolutely do not or cannot exist on the J-20 in any form. Metamaterials are in wide use on many fighter types and these materials have been around for decades. I have ALREADY told you my specific bone of contention, which is whether UHF-specific metamaterials are in use right now on the J-20, which both goes against the grain of current stealth technology application AND is not actually demonstrated to exist in any real world application, whether on the J-20 or in any other fighter, or in any other application at all.

 

[Klon]

Wow. Just wow. I just posted for you the entire sequence of post and repost between myself and plawolf and you have decided to completely ignore this series of posts, and are now calling the entire purpose of the debate between myself and plawolf a "moot point". No, tough guy, it is not a "moot point". It is the ENTIRE POINT. UHF band is NOT a band that is a focus of stealth technologies for use on fighters, which are invariably tuned to maximally attenuate against high frequency bands like X and Ka, the bands that fighter and missile radars typically use, and to a lesser extent C and S bands, the bands that MFRs typically use. IIRC the F-35's skin even has some effectiveness against L band. But UHF and VHF bands? Name me one other fighter whose stealth features have been specifically designed to defeat these bands. That is why UHF-specific metamaterials use on stealth fighters are a big deal, because this goes against established practice. I'm not saying this means that it is impossible that stealth fighters in the future will use UHF-attenuating technologies, but certainly the bar is higher and you DON'T get to use sloppy logic to try and win points here. What it also means is that the J-20 currently remains vulnerable to detection by AEW&C aircraft that transmit in UHF and VHF bands, i.e. planes like the AWACS, and by surface radars that transmit in those bands. It is the same principle that Chinese "anti-stealth" radars use to detect fighters like the F-22 and F-35.

And you are dead wrong about UHF/VHF vs other frequency bands as far as metamaterials are concerned. What this tells me is that you are either deliberately ignoring the physics or you don't even know the physics and you didn't actually do your due diligence. The lower the frequency band you are trying to defeat, the larger/thicker your metamaterial needs to be, which is obviously a problem as far as aerospace applications are concerned. Here is an article from last year describing a potential solution for this problem (for a VHF-specific ultra-thin metamaterial):

Please, Log in or Register to view URLs content!

And another one from 2015:

Please, Log in or Register to view URLs content!

Neither of them mention any degree of readiness for real world application. In fact the second citation notes a thickness achieved of 7.8mm. That's three quarters of a cm. Imagine that on the skin of a fighter when traditional RAM coatings are massively thinner.


Again, I have ALREADY told you before, that I am NOT concerned about the use of metamaterials in general on the J-20 and never was. If you think I was then link and post where I said that metamaterials absolutely do not or cannot exist on the J-20 in any form. Metamaterials are in wide use on many fighter types and these materials have been around for decades. I have ALREADY told you my specific bone of contention, which is whether UHF-specific metamaterials are in use right now on the J-20, which both goes against the grain of current stealth technology application AND is not actually demonstrated to exist in any real world application, whether on the J-20 or in any other fighter, or in any other application at all.

Please, Log in or Register to view URLs content!

Abstract

A radar absorbing composite includes a (CNT)-infused fiber material disposed in at least a portion of a matrix material. The composite absorbs radar in a frequency range from about 0.10 Megahertz to about 60 Gigahertz. The CNT-infused fiber material forms a first layer that reduces radar reflectance and a second layer that dissipates the energy of the radar. A method of manufacturing this composite includes disposing a CNT-infused fiber material in a portion of a matrix material with a controlled orientation of the CNT-infused fiber material within the matrix material, and curing the matrix material. The composite can be formed into a panel which is adaptable as a structural component of a transport vessel or missile for use in stealth applications.

Original Assignee: Lockheed Martin Corp

BACKGROUND
Low observable, or stealth, technology is utilized on aircrafts, ships, submarines, and missiles, for example, to make them less visible or observable to radar, infrared, sonar and other detection methods. Various radar absorbing materials (RAMs), which absorb electromagnetic frequencies, such as in the radar range, have been developed for such low observable applications. However, the RAMs presently employed have some drawbacks. For example, many RAMs are not an integral part of the surface of a low observable structure. Instead, the RAMs are applied as coatings or paints over the surface of the low observable structure making them heavier, and prone to wear, chipping, and failure. An example of such a RAM includes iron ball paint, which contains tiny spheres coated with carbonyl iron or ferrite. Moreover, these coatings require bonding to the surface of the structure because they are not an integrated part of the structure or surface.

Another example of a RAM is urethane foam impregnated with carbon. Such RAMs are used in very thick layers. Such RAMs are inherently non-structural in nature such that they add weight and volume to structures while providing no structural support. These types of foam RAMs are frequently cut into long pyramids. For low frequency damping, the distance from base to tip of the pyramid structure is often 24 inches, while high frequency panels can be as short as 3-4 inches.

Another RAM takes the form of doped polymer tiles bonded to the surface of the low observable structure. Such tiles which include neoprene doped with carbon black or iron particles, for example, are prone to separation, particularly in extreme operating environments such as extremely high or low temperatures, and/or high altitudes. Finally, numerous RAMs do not perform adequately in the long radar wavelength band, about 2 GHz.

It would be beneficial to develop alternative RAMs that address one or more of the aforementioned issues. The present invention satisfies this need and provides related advantages as well.

SUMMARY OF THE INVENTION
In some aspects, embodiments disclosed herein relate to a radar absorbing composite that includes a (CNT)-infused fiber material disposed in at least a portion of a matrix material. The composite is capable of absorbing radar in a frequency range from between about 0.10 Megahertz to about 60 Gigahertz. The CNT-infused fiber material forms a first layer that reduces radar reflectance and a second layer that dissipates the energy of the absorbed radar.

DETAILED DESCRIPTION
Moreover, the radar absorbing composite materials can be integrated as part of the surface and/or the overall structure of the low observable. In some embodiments, the entire structure can function as a RAM, obviating the issues of wear, chipping and the like associated with coated RAM paints, for example. Significantly, unlike the urethane-type foams, the RAMS of the present invention are structural and thus, substantial weight reductions can be achieved relative to their foam counterpart. In some embodiments, CNT-infused fiber materials can be employed as a coating while avoiding the problems associated with chipping/wear, and the like due to the extended lengths of fiber material employed.

 

[taxiya]

Wow. Just wow. I just posted for you the entire sequence of post and repost between myself and plawolf and you have decided to completely ignore this series of posts, and are now calling the entire purpose of the debate between myself and plawolf a "moot point". No, tough guy, it is not a "moot point". It is the ENTIRE POINT. UHF band is NOT a band that is a focus of stealth technologies for use on fighters, which are invariably tuned to maximally attenuate against high frequency bands like X and Ka, the bands that fighter and missile radars typically use, and to a lesser extent C and S bands, the bands that MFRs typically use. IIRC the F-35's skin even has some effectiveness against L band. But UHF and VHF bands? Name me one other fighter whose stealth features have been specifically designed to defeat these bands. That is why UHF-specific metamaterials use on stealth fighters are a big deal, because this goes against established practice. I'm not saying this means that it is impossible that stealth fighters in the future will use UHF-attenuating technologies, but certainly the bar is higher and you DON'T get to use sloppy logic to try and win points here. What it also means is that the J-20 currently remains vulnerable to detection by AEW&C aircraft that transmit in UHF and VHF bands, i.e. planes like the AWACS, and by surface radars that transmit in those bands. It is the same principle that Chinese "anti-stealth" radars use to detect fighters like the F-22 and F-35.

And you are dead wrong about UHF/VHF vs other frequency bands as far as metamaterials are concerned. What this tells me is that you are either deliberately ignoring the physics or you don't even know the physics and you didn't actually do your due diligence. The lower the frequency band you are trying to defeat, the larger/thicker your metamaterial needs to be, which is obviously a problem as far as aerospace applications are concerned. Here is an article from last year describing a potential solution for this problem (for a VHF-specific ultra-thin metamaterial):

Please, Log in or Register to view URLs content!

And another one from 2015:

Please, Log in or Register to view URLs content!

Neither of them mention any degree of readiness for real world application. In fact the second citation notes a thickness achieved of 7.8mm. That's three quarters of a cm. Imagine that on the skin of a fighter when traditional RAM coatings are massively thinner.


Again, I have ALREADY told you before, that I am NOT concerned about the use of metamaterials in general on the J-20 and never was. If you think I was then link and post where I said that metamaterials absolutely do not or cannot exist on the J-20 in any form. Metamaterials are in wide use on many fighter types and these materials have been around for decades. I have ALREADY told you my specific bone of contention, which is whether UHF-specific metamaterials are in use right now on the J-20, which both goes against the grain of current stealth technology application AND is not actually demonstrated to exist in any real world application, whether on the J-20 or in any other fighter, or in any other application at all.

I will save my time as @Klon just answered your fixation of UHF/VHF or whatever frequency you are trying to nit-pick. It is a moot concern, and you just try to hang on to it to avoid that you missed or ignored or not knowing something.

 

[SamuraiBlue]

I will save my time as @Klon just answered your fixation of UHF/VHF or whatever frequency you are trying to nit-pick. It is a moot concern, and you just try to hang on to it to avoid that you missed or ignored or not knowing something.

Ughhh, The abstract Klon posted is a description of RAM or Radar Absorbing Material not the recent Buzz word Meta-material.
Meta-material is a 3 Dimensional shape that does not occur in nature which has special properties.

As for your posting;

That is one part of metamaterial. The other part as I read is capacitors fabricated on the sheet. If the 3D matrix is seen as wave-guide and micro antennas, the capacitors can be seen as tuners in a radio receiver which set the receiving bandwidth to a range rather than a point. There are more things metamaterial can do, it is essentially a PCB with micro antennas, inductors and capacitors (so far today), and even (in the future) micro transistors to do more things.

This is just techno gibberish.
Whether natural occurring structure or meta-material structure it all has a natural resonating frequency. With out some kind of outside source of energy you can't change frequency of a wave which you are suggesting.
The closest thing you suggest is Smart Skin technology that Japan is doing research in which they vibrate the outer skin of a plane with plasma to emit or cancel out low energy radar just like sound cancellation system you see in ear phones these days.