J-20 5th Gen Fighter Thread VI

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broadsword

Brigadier
Yes, my point was that a quantum leap in metamaterial application, if achieved, may well not be publicly acknowledged in detail.

As for assertions of a world first, maybe I'm a jaded cynic, but that invariably arouses my suspicions. If you do some research, it so often turns out that somebody else has been doing it for ages (even when the claim originates in the specialised press rather than mass media) that it's not even funny. I mean, Kinzhal is the world's first air-launched ballistic missile, Gutenberg invented movable type and GE pioneered swept fan blades & 3D compressor aerodynamics*, right?

* A favourite example of mine - poorly known, but extremely impressive. I'd rather not digress, but can certainly elaborate if there is interest.

Did China, or its media, claimed it was the first instead for those inventions? Sometimes it media are sloppy with its reporting.
 

Quickie

Colonel
...... I mean, Kinzhal is the world's first air-launched ballistic missile, Gutenberg invented movable type and GE pioneered swept fan blades & 3D compressor aerodynamics*, right?

The movable type was first invented in China a few hundred years before the time of Gutenberg's movable type. Maybe, Gutenberg has "Christian missionaries, traders and business people" to thank for his invention.


various sporadic reports of movable type technology were brought back to Europe by Christian missionaries, traders and business people who were returning to Europe after having worked in China for several years and influenced the development of printing technology in Europe. Some of these medieval European accounts are still preserved in the library archives of the
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and
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among many others.

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Hendrik_2000

Lieutenant General
Nothing much here it is
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J-20 Chief Engineer Talks NextGen Hunter
BY
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If the latest generation of fighter aircraft, characterized by a different degree of low observability, a strong awareness of the operational situation and increased survivability in the theater of intervention, is already beginning to enter a new era of maturity, including the programs like the F-22 and the American F-35, the Russian Su-57 as well as the Chinese J-20 and FC-31, the next-generation hunter criteria are still far from being defined.

How will an air combat take place in 15 to 20 years? What will be the role of fighter jets in future scenarios? What will be the technological requirements to meet the economic needs and the ground of tomorrow? With or without drivers? These are the questions that major air forces and aircraft manufacturers are beginning to ask themselves.

And YANG Wei (杨伟), chief engineer of the J-20 program and a member of the Chinese Academy of Sciences, gave for the first time his vision on these issues recently.

"We will define the standards of the fighter jet of the future"
"Before, we look at what others are doing and we are following," says YANG in
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in Beijing, "But today we are able to conceive and to provide only what the country's strategy needs. "

For this chief engineer who led several military programs at the 611 Chengdu Institute, one of AVIC's major design offices, China's military aviation sector has now entered a "kingdom of freedom", in which the armed forces can have confidence in the "Made in China" equipment and define their own strategic objectives and arms development paths, and that the industrialists can create and innovate without having to rely on the "foreign antecedents" , and show much more confidence about their own technologies.

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A serial J-20 comes out of the assembly line in Chengdu (Photo: Jacksonbobo)

"We had to understand why and how others do this and that in the past, and only when we see that others are successful in these choices are we confident we will follow them and do the same at home" says the man who was promoted to head of the design office at the age of 38, "Now even if the laws of physics are the same for everyone, we are able to define our own needs that are unique, and our technological path is entirely independent. "

"I had a goal before, I wanted to reach such a level that our opponents are forced to study us. Today I have another one, I want it to be China that sets the world's next-generation hunter standards. "

J-20 is not just a "ram"
Some analysts in China described the new J-20 fighter as a "ram" used to "smash" an enemy country's air carrier, "a needle that will pierce the net". As the program's chief engineer, YANG has another understanding.

"In the current family of Chinese hunters, the J-20 is the most powerful member. And as he is the strongest Chinese carrier in air superiority, he will inevitably be used in the most critical scenarios in the fight, "says YANG," but qualifying him as a ram is a bit of a let down. "

"How to use a jet fighter also depends on its number in staffing. When the series is still small it will be deployed for some applications, but when the series is bigger it will be another story. "

According to YANG, the J-20 is still at the beginning of its history and the program is already planning to develop other variants.

"It meets the needs of the country and it was the case for the J-10 program which is still in development, we will not stop there for the J-20. "

A mix of mechanical, computer and intelligent platform
In response to the question of how will be the fighter of the future, the 55-year-old Chief Engineer speaks with some restraints.

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The DMU of J-10A (Image: AVIC)

"The Americans had defined the 4S criteria for their fifth-generation fighter planes, but these criteria are not very prescriptive. Today the United States, Russia and China all have their own new generation fighter planes, but the weight placed on each of these criteria varies according to the needs and visions that are specific to each country. "

For YANG, the world's mechanical engineering has yet to cross a "threshold" before it can serve as a base for next-generation fighter aircraft. But once this threshold is passed, its contribution to efficiency and overall combat performance will be greatly reduced.

Although he did not explain what this "threshold" represents, but it is thought that this is the limit of the current aerodynamics and also that which the human body can bear.

"The key lies in computerization and (artificial) intelligence," says the one who is considered a symbol of military aviation design in China, "I think the next-generation fighter will be on the hunt for an even higher level of computerization and artificial intelligence, while relying on a good mechanical platform that remains scalable and adaptive. "

Driver, unmanned?
Faced with the question of whether drones will be the main vectors of the future, YANG thinks that (artificial) intelligence has two objectives - to help the pilot, or to replace the pilot.

"Personally I will not focus on the pilot or unmanned issue. The integrated intelligence between the man and the machine will continue to bring greater efficiency for a certain future period. "

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Two J-20 of the Chinese Air Force train in a military exercise (Photo: CCTV)

In the short and medium term, YANG remains convinced that the development of military air vectors will rely on mechanical engineering, computerization and artificial intelligence. He sees in mechanics the basis and the carrier of all equipment, while computerization will be the amplifier of performance, and artificial intelligence as technology of "rupture".

"Network + and System + will be the breaking points for any development of military equipment of the future",

Henri K.
 

Tirdent

Junior Member
Registered Member
If I interpret you right, you are saying other (existing) 5th gen aircrafts (F-22 and F-35) are already using (same or other type) frequency selective treatment?

Correct.

FSS (also sometimes called "bandpass") radomes keep RF outside radar's own band from entering the radome. This means that RCS reduction efforts on structure and equipment inside need only to concern themselves with a narrow bandwidth (e.g. only X-band for a fighter radar), making the job much easier.

Many post-1990 combat aircraft use this technology:

Eurofighter Typhoon

Aviation Today said:
Eurofighter's radome is a complex glass-reinforced plastic (GRP) structure manufactured to close tolerances. It includes layers of frequency-selective surface (FSS) materials, comprising metallic micro-arrays that absorb all frequencies outside the band of the aircraft's own radar.

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Rafale

Jane's IHS said:
However, Dassault and Thales are not proposing to make the AESA the all-encompasing RF cuisinart that Boeing (for example) envisages for the Super Hornet, with features such as passive detection, multi-beam operation and jamming. Nor does the team intend to exploit the AESA's wide bandwidth, which would mean a new radome. (This suggests that the current radome is a bandpass design, transparent at the RBE2 frequency but stealthily reflective at any other.)

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F-22 (and by extension F-35, although I can't find a source on the fly which explicitly says so)

Bill Sweetman said:
The radome is a "bandpass" type that reflects signals at all frequencies except the precise wavelengths used by the F-22 radar.

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USAF said:
Multiple design options were explored during the DemVal phase of the program with the YF-22 band pass concept (Lockheed, Boeing, General Dynamics) being the chosen design strategy at program source selection. Figure 10 illustrates the frequency filtering characteristics of the IFB which allow for transmissions but limit exposure of the radar antenna and forward cavity to outside radiators.

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Lockheed Martin said:
The F-22 design significantly reduces the radar’s signature using a combination of a bandpass resonant radome and low signature radar. The F-22 radome is one of the most complex structural components on the F-22.

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David C. Aronstein said:
The F-22 wideband radome was originally novel and high risk, especially from a manufacturing perspective. The design at the end of Dem/Val consisted of drilling hundreds of small holes and filling them with plugs to provide the correct antenna patterns and coverage across the frequencies of interest. The breakthrough in EMD involved etching the surface of the frequency selective substrate.

There may be others (what looked a lot like a FSS shroud was shown in an internal Sukhoi document, Gripen).

Part of the issue here is a classic "buzzword" problem - AFAIK the term metamaterial was only coined in the late 1990s, yet research (and in some cases even application) of technologies in this field goes back decades longer. So if you are not conversant with what "metamaterial" actually means, it is easy to miss references to examples which date from before the phrase had even entered the dictionary. Google Eurofigher + metamaterial and you will probably not find anything relevant while Eurofighter + frequency selective surface generates loads of results - but it requires you to figure out that a frequency selective surface is a typical case of what would nowadays be referred to as a metamaterial.

Think "supercruise" - Concorde had been doing it better than any 5th generation fighter for ages before the word was even invented :) And that's without getting into the problem of different languages - catch phrases for a certain technology might exist in one but not the other or be so different that it's not immediately recognisable that they're synonymous. Hell, even in English sometimes a frequency selective radome is a bandpass radome, as mentioned!

Did China, or its media, claimed it was the first instead for those inventions? Sometimes it media are sloppy with its reporting.

No, but that wasn't my point. All of those are examples of things hailed to be unique or world firsts, yet were pioneered by people/organisations other than those which are commonly credited (or like to take credit) for them today. The intent being to show that such claims frequently don't stand up to closer scrutiny.

The movable type was first invented in China a few hundred years before the time of Gutenberg's movable type. Maybe, Gutenberg has "Christian missionaries, traders and business people" to thank for his invention.

Exactly - so many alleged world firsts are in fact incorrectly attributed, including all of those I mentioned there.

Though Gutenberg's innovations did move the state of the art in printing forward regardless, so despite the fact that he did not come up with the basic concept he did improve the process considerably. He is to movable type what Dunlop and his pneumatic tyre were to the wheel :)
 

taxiya

Brigadier
Registered Member
Correct.

FSS (also sometimes called "bandpass") radomes keep RF outside radar's own band from entering the radome. This means that RCS reduction efforts on structure and equipment inside need only to concern themselves with a narrow bandwidth (e.g. only X-band for a fighter radar), making the job much easier.

Many post-1990 combat aircraft use this technology:

Eurofighter Typhoon

Eurofighter's radome is a complex glass-reinforced plastic (GRP) structure manufactured to close tolerances. It includes layers of frequency-selective surface (FSS) materials, comprising metallic micro-arrays that absorb all frequencies outside the band of the aircraft's own radar.

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Rafale

However, Dassault and Thales are not proposing to make the AESA the all-encompasing RF cuisinart that Boeing (for example) envisages for the Super Hornet, with features such as passive detection, multi-beam operation and jamming. Nor does the team intend to exploit the AESA's wide bandwidth, which would mean a new radome. (This suggests that the current radome is a bandpass design, transparent at the RBE2 frequency but stealthily reflective at any other.)

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F-22 (and by extension F-35, although I can't find a source on the fly which explicitly says so)



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Multiple design options were explored during the DemVal phase of the program with the YF-22 band pass concept (Lockheed, Boeing, General Dynamics) being the chosen design strategy at program source selection. Figure 10 illustrates the frequency filtering characteristics of the IFB which allow for transmissions but limit exposure of the radar antenna and forward cavity to outside radiators.
upload_2018-3-19_21-47-16.png

David C. Aronstein said:
The F-22 wideband radome was originally novel and high risk, especially from a manufacturing perspective. The design at the end of Dem/Val consisted of drilling hundreds of small holes and filling them with plugs to provide the correct antenna patterns and coverage across the frequencies of interest. The breakthrough in EMD involved etching the surface of the frequency selective substrate.
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Thanks for your effort providing the information. Here is my understanding.

  • The language regarding Rafale is "suggest", without details of how. I can't make out anything so I leave it out.
  • The figure 10 of F-22 shows it to reflect (scatter) incoming radar waves to many directions therefor reducing the return. The description from David C. Aronstein says mechanically fabricate the patterns (holes and plugs). Is there specific patterns? The pattern is critical.
  • Eurofighter's key words are "metallic micro-arrays that absorb", this is the closest to what is described in the CCTV program. However we don't know the fabrication process which determines whether one can create the optimum pattern at will.

The principle of them and the "metamaterial" in CCTV is the same, that is to create a surface with appropriate patterns of conductors to absorb (best) or reflect incoming radar waves. There is no doubt of this, neither do I see CCTV program exaggerating by claim uniqueness in this regard.

What CCTV claims unique is to be the first to mass produce a material with desired pattern at will. Both the size (80cm x 80cm) film plate and photo-printing (like LCD screen's micro conductors). This is surely different from F-22, and to be honest much more advanced and cheaper. Think about the work and cost of drilling hundreds of thousands of small holes on some composite plate with precise dimensions, compared with the fabrication in a printer. This can be done for a radome, but would be too costly to cover the whole aircraft, while a film based plate can do cheaply. It is like "hand soldering a circuit vs. printed board".

In the end, my conclusion (for now) remains the same, regardless what the name is (metamaterial or FSS, IFB), the only thing that CCTV claimed was "first mass" production of such material, nothing else.
 
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davidau

Senior Member
Registered Member
...from the British Janes Defence Weekly website published the report of the Gabriel Domingues, entitled "China launches the 6th generation fighter aircraft research and development, will develop new type -20".....
...simply stunning! ...

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plawolf

Lieutenant General
The key difference between meta materials and composit materials that came before is the critical distinction that the internal structure of a meta material is purposely designed according to a carefully calculated optimal model, and manufactured to meet those design specifications.

Traditional composite materials OTOH, are more production driven, whereby accumulated production and manufacturing experience showed that if you add X material, treated it in A way, then add Y material, and treat it in B way, you get a material with new and interesting properties.

The two are like two people starting from opposite ends of a spectrium and both working towards the same middle ground. They both have the same goals, and will often face the same kinds of problems. Hell, they may even hold the solutions to each other’s problems. One is driven by the structural design, while the other is driven by the manufacturing processes.

As a very simplistic illustration, have the X axis as cost per unit, and the Y axis as the closeness to the theoretical optimal, with the trade off between the two exactly proportional so you have a nice easy straight line plot going diagonally upwards from left to right.

Traditional manufacturing starts at the bottom left, with minimal unit cost, but far from the theoretical optimal, and they work it’s way up, accepting higher costs for better performance. OTOH, meta materials start form the top left, with something tailor made in a lab to be as close to the theoretical optimal as possible, but they tend to work their way down as performance compromises are accepted to bring costs down to affordable levels and yield up to useful quantities.

As a general rule, the starting points of the two sides tend to also significantly influence their end points, where they settle on a marketable product and go for mass production. So traditional manufacturing driven R&D will tend to settle for lower costs but worse performance, while meta material designers tend to accept higher cost for better performance.

Think of composite materials as like dog breeding. There is a lot of skill and science to it, but the core underlying mechanics of it are down to natural processes and learnt from trial and error.

Meta materials is like gene selective IVF/cloning. You have much more fine control of the end result, but it costs a lot more.

Thus, there are a lot of linkage between traditional manufacturing driven materials sciences and lab driven meta material sciences, since a fundamental bottleneck with meta materials is mass production.

It’s all well and good to design a mathematically ‘perfect’ material structure that does all kinds of wonderful and amazing things. However, if you need a bleeding edge 3D printer to print it at the atomic level and could only make minute trace amounts of the stuff at exorbitant cost, it isn’t really going to be of much benefit in practice.
 

Klon

Junior Member
Registered Member
If I interpret you right, you are saying other (existing) 5th gen aircrafts (F-22 and F-35) are already using (same or other type) frequency selective treatment?
I'm pretty sure there's a misunderstanding, in that what's used in radomes is by now quite common and presumably not the same thing being hinted at in the CCTV report. If that's so, there's not much to clear up.
(Disclaimer: this comment made without any technical knowledge.)

Just out of curiosity, what does the "
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" qualify as?
 
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