J-20... The New Generation Fighter

Re: New Generation Fighter

latenlazy said:

If you're talking about metamaterials, it's not just China and the US putting research to the concept. I highly doubt any of these countries see this research as implementable any time in the near future. China, like any other country, does the research so that it doesn't fall behind the curve.

No country has this technology currently implemented. The concept was only properly demonstrated on the nano scale in the last year or two. To even make stuff like this on a large scale we need huge advances in nanoscale manufacturing that could be decades off. And it's not a "composite material".

EDIT: I forgot to mention in this particular case the metamaterial in question doesn't even pertain to stealth. Note that the material doesn't bend the light to have a zero angle of incidence, which means you can see the light behind the object, but that it absorbs the light entirely so that the em radiation is trapped, which makes the object a "black hole".

Click to expand...

The device, as reported above, only works on microwave. A earlier report on the same research noted that the researchers were planning to built a device that works on light waves but no mention was made as to whether it can be implemented on radio waves.

Re: New Generation Fighter

Quickie said:

The device, as reported above, only works on microwave. A earlier report on the same research noted that the researchers were planning to built a device that works on light waves but no mention was made as to whether it can be implemented on radio waves.

Click to expand...

When I said light I meant electromagnetic radiation. Different materials will be effective for different frequencies of em radiation. This article is a big deal because up till now most metamaterials have only been able to bend very specific frequencies (or at best a narrow band). Of course, all this has very little to do with the j-xx.

Re: New Generation Fighter

latenlazy said:

When I said light I meant electromagnetic radiation. Different materials will be effective for different frequencies of em radiation. This article is a big deal because up till now most metamaterials have only been able to bend very specific frequencies (or at best a narrow band). Of course, all this has very little to do with the j-xx.

Click to expand...

What I meant was the researchers is planning on building another device that works on the higher frequency light waves. No mention was made of this for radio waves which is more concerned with the kind of radar stealth we're interested in.

Re: New Generation Fighter

Most radar, I believe, is in microwave frequency. X-band radar, for instance, is 8-12 ghz, while the materials test was in the Ku-band.

I do agree with you on two counts; one, the main civilian use of this technology will be in solar cells as an alternative to large mirrored arrays; you set up a visible light absorber somewhere in the desert, attach it to a stirling engine, and you have what is effectively a two-stage electrical power generator, since if the radiation absorber is as efficient as they advertise (99%!) you don't see the same problems with traditional solar stirling engines where having to convert light energy to heat creates a significant efficiency loss in the process.

For military use, I agree on the emissions hole problem. The key weakness of this as a stealth technology is that the resulting aircraft will show up as a black displacement against background radio emissions. You also have a potential weakness where if sufficient levels of high-energy radar are directed at this material, you could have the plane just explode from the inability to rid itself of heat energy. Perhaps they could implement a semiconductor control into this system in order to modulate radar emissions based on background noise.

Re: New Generation Fighter

Inst said:

Most radar, I believe, is in microwave frequency. X-band radar, for instance, is 8-12 ghz, while the materials test was in the Ku-band.

I do agree with you on two counts; one, the main civilian use of this technology will be in solar cells as an alternative to large mirrored arrays; you set up a visible light absorber somewhere in the desert, attach it to a stirling engine, and you have what is effectively a two-stage electrical power generator, since if the radiation absorber is as efficient as they advertise (99%!) you don't see the same problems with traditional solar stirling engines where having to convert light energy to heat creates a significant efficiency loss in the process.

For military use, I agree on the emissions hole problem. The key weakness of this as a stealth technology is that the resulting aircraft will show up as a black displacement against background radio emissions. You also have a potential weakness where if sufficient levels of high-energy radar are directed at this material, you could have the plane just explode from the inability to rid itself of heat energy. Perhaps they could implement a semiconductor control into this system in order to modulate radar emissions based on background noise.

Click to expand...

I think the solution you proposed sounds like a good one. I don't think the high-energy radar would be a problem, you can't aim at what you can't target, and if it can be targeted, then it's obviously not of that much use for stealth purposes. It'll be a long time before this thing can be militarized either way.

Re: New Generation Fighter

The F-35 and F-22 are supposed to be using radar absorbing composites. If I recall correctly, modern US stealth aircraft is both based off stealth-shaping, stealth composites, and radar absorbing paint. The Russians and the Chinese have a very good idea of the radar absorbing paint part, the stealth shaping is also pretty well-understood, but perhaps they're both underestimating the effects of stealth composites.

As to whether this metamaterial can be categorized as a composite; well, it's based off two materials, a circuit board and copper wiring. Isn't that a composite?

Re: New Generation Fighter

Inst said:

The F-35 and F-22 are supposed to be using radar absorbing composites. If I recall correctly, modern US stealth aircraft is both based off stealth-shaping, stealth composites, and radar absorbing paint. The Russians and the Chinese have a very good idea of the radar absorbing paint part, the stealth shaping is also pretty well-understood, but perhaps they're both underestimating the effects of stealth composites.

As to whether this metamaterial can be categorized as a composite; well, it's based off two materials, a circuit board and copper wiring. Isn't that a composite?

Click to expand...

Maybe if you call it a "nanoscale" composite. The most important feature of a metamaterial is that different materials are arranged at a particle by particle level to minutely control the defraction of light. A solution to the "black hole" problem is completely unnecessary. The first demonstration of a metamaterial was a bending of light to make that material and everything inside it completely transparent to specific frequencies of em radiation. In other words, once this technology is mastered and a way to produce them en masse is found, we could essentially make things "invisible".

Metamaterials are fundamentally different from the "stealthy" composites you're talking about. Though someone else will have to fill in the details, my understanding is that those composites don't reflect radar waves as strongly because they're dielectric materials. I think the Chinese and the Russians using higher levels of composites to reduce the RCS of the Su-27 is a good example of their understanding of that technology. To make use of a metamaterial for stealth it's likely that it would work more like RAM, being the most outer coat of a fighter to directly redirect light around the fighter (RAM merely absorbs the radiation and converts it to heat). In fact, if metamaterials are used for stealth they could replace every other design aspect of a stealth fighter. We could go back to an age where fighters are solely designed with aerodynamics in mind.

Re: New Generation Fighter


Hi guys.
I noticed that the section dedicated to J-11B is smaller than J-11A's one.
Does anyone have some new official info to add to?

Re: New Generation Fighter

I don't think at this type of implementation you need nanoscale structures; the wavelength of 16 ghz is 1.88 CM or 18.8 mm. With low frequency microwaves nanoscale structures aren't necessary. For visible light, on the other hand, you have wavelengths in the hundreds of nanometers.

Re: New Generation Fighter

Early proposal of the 5th generation fighter, found from here:




Judging by the text shown, it should be fighter design during concept stage, in the middle its the 611's proposal, so one may expect there could be alot of changes through, of cause, given the pic hold some truth.

Anyway, dont know how creditable the source is, but this is definitely a pic I have never seen before, so just some food for thought.