Chengdu J-20 5th Generation Aircraft News & Discussions

[Deino]

https://twitter.com/x/status/997739075254800385

 

[LKJ86]

 

[siegecrossbow]

https://twitter.com/x/status/997739075254800385

I think you meant composite, Deino.

 

[LKJ86]

I think you meant composite, Deino.

What did he post?

 

[siegecrossbow]

What did he post?

"Interesting composed image showing a J-20A during a sharp turn"

 

[LKJ86]

"Interesting composed image showing a J-20A during a sharp turn"

I have posted a repeated picture.

 

[LKJ86]

AVIC CG

https://mp.weixin.qq.com/s/pVizjmB_H-5uNjyYdyH3VQ

 

[samsara]

I think you meant composite, Deino.

Nope, Deino did mean "composed" i/o "composite".

One of the many meanings of the word "to compose" : to arrange to make a pleasing picture, artwork, etc, which fits the fascinating circular pics.

 

[Gomig-21]

Any idea why Chinese designer's preferred using explosive chords in the glass canopy of the J-20 instead of a fully ejectable canopy in order to reduce that ever so critical RCS that is compromised by the radar and other avionics from inside the cockpit?

It seems to me that the canopy with a chord in it emits more of a return than one without. Anyone know if they ever spoke about that?

 

[LKJ86]

Any idea why Chinese designer's preferred using explosive chords in the glass canopy of the J-20 instead of a fully ejectable canopy in order to reduce that ever so critical RCS that is compromised by the radar and other avionics from inside the cockpit?

It seems to me that the canopy with a chord in it emits more of a return than one without. Anyone know if they ever spoke about that?

It takes the style of F-35.

 

[Pepsi Cola]

Any idea why Chinese designer's preferred using explosive chords in the glass canopy of the J-20 instead of a fully ejectable canopy in order to reduce that ever so critical RCS that is compromised by the radar and other avionics from inside the cockpit?

It seems to me that the canopy with a chord in it emits more of a return than one without. Anyone know if they ever spoke about that?

It is an explosive cord which helps to crack the canopy before the ejection seat has to do this all by itself. When ejection is commanded, the harness is tightened and the canopy is shattered, and only then the real ejection starts. Earlier designs would blow the full canopy off, but this takes longer than shattering it, especially when the canopy is large.

Some seats have their own canopy breakers, but thick, tough canopies which are needed for flying at high dynamic pressure and for surviving bird strikes would slow the seat down too much. The F-16 canopy is 12mm thick in the area above the pilot. They are used widely for both land- and carrier-based aircraft, and modern designs try to make them less obvious. The F-35 canopy uses just one line down the middle.

Credit: https://aviation.stackexchange.com/questions/12821/what-are-these-wavy-lines-on-fighters-canopy

 

[Gomig-21]

It is an explosive cord which helps to crack the canopy before the ejection seat has to do this all by itself. When ejection is commanded, the harness is tightened and the canopy is shattered, and only then the real ejection starts. Earlier designs would blow the full canopy off, but this takes longer than shattering it, especially when the canopy is large.

Yes, I'm familiar with how they work. I was asking why they chose that particular detonation chord and particularly that pattern. The jet is impeccably designed in almost every single aspect to reduce RCS and adding that zig-zag detchord pattern seems to defeat the purpose a little bit. Maybe I'm wrong, but to me, I think it's basically like an antenna, if you think about it, and adding an antenna to an already heavily electronically filled glass canopy seems like a step back to otherwise a lot of effort to reduce RCS. I was wondering if they ever spoke about it and if it might be temporary or if it is indeed the final system they're going with.

Some seats have their own canopy breakers

Head seat spikes are a thing of the distant past. That's probably the WORST way to crack a canopy and makes it 10 times more of a violent and dangerous experience for a very stressed pilot when it needs to be as least stressful as possible. I'm glad they didn't go anywhere near that.

They are used widely for both land- and carrier-based aircraft, and modern designs try to make them less obvious. The F-35 canopy uses just one line down the middle.

That's what I was getting at. If the detchord is the way the Chinese engineers wanted to go, I would've thought they would have designed a lot less conspicuous layout like the F-35 or even used the full canopy jettison system.

Not that the F-35 is the standard to go by and neither is the F-22 which incorporates the full canopy jettison system, there are pros and cons for both systems but if we do look closely at the F-35, its detchord not only runs down the middle of the top part in one straight line like you mentioned (reducing as much chord as possible), but it travels along the front and bottom rails where the glass connects to the frame and back. It essentially splits the glass into two leafs from the frame. Kind of in-between a full canopy jettison and a zig-zag detchord just on the top but more importantly, it's less conspicuous.

It seems they took a lot of considerations into designing it not only for effectiveness, but specifically for lower RCS and any additional electronic emissions from the glass cockpit. They also had to consider that one of the three models is a carrier-based variant and the STOVL aircraft has a greater risk of dropping into the water. A detchord system is much better suited for that than a full canopy jettison. The latter doesn't work so well when the aircraft is submerged in water.

But even with all those safety and water considerations, it seems they also made an effort to minimize something that would seem to increase the aircraft's RCS, and that's what I was wondering about the J-20.

 

[LKJ86]

http://www.81.cn/jskj/2018-05/16/content_8033754_2.htm

 

[siegecrossbow]

Any idea why Chinese designer's preferred using explosive chords in the glass canopy of the J-20 instead of a fully ejectable canopy in order to reduce that ever so critical RCS that is compromised by the radar and other avionics from inside the cockpit?

It seems to me that the canopy with a chord in it emits more of a return than one without. Anyone know if they ever spoke about that?

Lighter weight is one reason.

 

[cirr]

China confirms use of mature stealth testing technology

2018-05-23 08:56:13 Global Times

Aircraft company showcases deployment of radar detection capabilities

China can comprehensively test the stealth capability of its aircraft and apply the mature technology to the design and manufacture of naval vessels, a military expert said Tuesday in response to a report in a technical review magazine.

Shenyang Aircraft Corporation successfully conducted a Radar Cross-Section (RCS) test for aircraft, according to the official WeChat social media account of Ordnance Industry Science Technology, a Chinese periodical on national defense industries and technologies.

This is the first time China has openly released information confirming its use of the RCS testing technology on stealth fighters.

Tuesday's report included a photo of a fighter jet like the J-11 and a research team from the corporation based in Northeast China's Liaoning Province.

Military analysts said the article proved that Chinese stealth capability has massively improved, with multiple Chinese military industrial research institutes able to maturely apply the technology to their production of more sophisticated weapons including ships and tanks.

RCS is a measure of how detectable an object is by radar. A larger RCS index indicates that an object is more easily detected by radar.

According to the report, China long ago gained the technology and applied it to the design and manufacture of China's most advanced fifth generation stealth fighter, the J-20.

"The J-20 is built by Chengdu Aircraft Industry Group, and Shenyang Aircraft Corporation is also conducting research and development of another China-made stealth fighter, the FC-31, so the technology is very basic and essential," Song Zhongping, a military expert and TV commentator said.

"If the RCS test can be used maturely, that means the fourth-generation fighter jets including the J-11 and J-16 that form the main body of the Chinese air force and are produced by Shenyang Aircraft Corporation, can also improve their stealth capabilities."

The RCS index largely depends on the object's size, configuration and materials.

Although the older fighter jets in commission cannot change their aerodynamic configuration, they can reduce their index with a stealth coating, Song noted.

"This means that apart from the J-20, some other aircraft in the Chinese air force also have stealth capability," he said.

Only a few countries in the world have stealth testing capability: the U.S., Russia and a few EU members can conduct the test, according to the report.

The technology can also be used for navy vessels and armored ground vehicles.

http://www.ecns.cn/news/military/2018-05-23/detail-ifyuqkxh5542964.shtml