Chengdu J-20 5th Generation Aircraft News & Discussions

[Han Patriot]

That is the smokiest engine i have ever seen... Hope I'm wrong.

This is smoke. The infaous Russian RDs

 

[Deino]

Fuel Dumping, not smoke

Indeed, however I'm surprised that the WS-10 also uses this unique system by the AL-31-series to dump fuel via the AB ... as far as I know no other engine (esp. no Western one) has this too.

 

[Han Patriot]

Indeed, however I'm surprised that the WS-10 also uses this unique system by the AL-31-series to dump fuel via the AB ... as far as I know no other engine (esp. no Western one) has this too.

Years of 'learning'.

 

[Speeder 2]

 

[onebyone]

J-20 fighter takes part in first combat exercises
By Zhao Lei | China Daily | Updated: 2018-01-12 07:26

Two J-20 fighter jets conduct an exercise. LI SHAOPENG/XINHUA
Fifth-generation jet, pilots put to test during realistic drills

The Chinese Air Force has deployed its best combat plane - the J-20 stealth fighter jet - to conduct exercises with other advanced jets.

The Air Force of the People's Liberation Army said in a news release on Thursday that several J-20s took part in a series of combat exercises against the less-advanced J-16 and J-10C.

The exercises took place over the past nine days at an undisclosed air base and were realistic, the release said.

The military said J-20s practiced beyond-visual-range aerial fighting maneuvers during these drills, without elaborating.

This is the first time the Air Force has confirmed that the J-20 has participated in a combat exercise. In July, the Air Force sent three J-20s to a military parade at the Zhurihe Training Base in the Inner Mongolia autonomous region and used that occasion to make public some details about the inside of the jet's cockpit for the first time.

In late September, a spokesman for the Defense Ministry confirmed at a news conference that the fifth-generation aircraft has been com-missioned to the Air Force.

Wu Peixin, an aviation industry observer in Beijing, said sending J-20s on combat exercises would not only enable its pilots to get familiar with the plane and its tactics as soon as possible, but also would help other aviators hone their skills on how to confront a cutting-edge fifth-generation jet in combat.

He said China faces a big challenge in the Asia-Pacific airspace from the F-22 Raptor and F-35 Lightning II - the other stealth fighters in service - deployed by the United States and Japan respectively, so it is urgent for Chinese pilots to know how to deal with such warplanes.

China conducted the maid-en flight of the J-20 in January 2011 and declassified the plane in November 2016.

Developed by Aviation Industry Corp of China, the State-owned aircraft giant, the J-20 shoulders the heavy responsibility given by the Air Force to create space for other aircraft during an air battle, according to Zhang Hao, head of an Air Force flight-testing center that has deployed the jet.

"J-20 will be like a needle that can penetrate and break down the enemy's air-defense network," he previously told China Central Television. "The plane is a typical offensive weapon. It has good stability, stealth capability, situational awareness capacity, and fire-control systems."

Yang Wei, chief designer of the J-20, has predicted the plane will be the backbone of the PLA Air Force for the next 20 years.

http://www.chinadaily.com.cn/a/201801/12/WS5a580a87a3102c394518eb05.html

 

[cirr]

Terahertz radar for J-20 in the future?

http://news.cctv.com/2018/01/11/ARTIdsFwXQoNdai48JtxuPY9180111.shtml

 

[siegecrossbow]

Terahertz radar for J-20 in the future?

http://news.cctv.com/2018/01/11/ARTIdsFwXQoNdai48JtxuPY9180111.shtml

Terahertz radars have notoriously short range. I doubt they'll be of much use.

 

[gambit]

Terahertz radar for J-20 in the future?

http://news.cctv.com/2018/01/11/ARTIdsFwXQoNdai48JtxuPY9180111.shtml

No, please perform basic research before you post. The basic research here is not about the J-20 but about the freq itself. You can put a thz system on the J-20 if you want, but it would effectively render the jet worthless in combat.

As pointed out in post 10147 that '...notoriously short range.'. Why is that ? It is called 'physics', as in real physics, not the garbage that is often concocted in this forum.

https://spectrum.ieee.org/aerospace/military/the-truth-about-terahertz

But the goal of turning such laboratory phenomena into real-world applications has proved elusive. Legions of researchers have struggled with that challenge for decades.

See that ? DECADES. And yet on PDF, it can be done in a few yrs.

What I really wanted were answers to questions like, What exactly are terahertz frequencies best suited for?

The application here is radar, of which the foundation of the real world application is the PULSE.

Radar detection needs REFERENCE POINTS. Anything that the radar computer can use to mark time. When a radar pulse is created, there are two reference points: leading and trailing edges.

But orbiting terahertz instruments have a big advantage over their terrestrial counterparts: They’re in space! Specifically, they operate in a near-vacuum and don’t have to contend with a dense atmosphere, which absorbs, refracts, and scatters terahertz signals. Nor do they have to operate in inclement weather.

Problem One: The terahertz freqs already have greater vulnerabilities to effects from various atmospheric phenomenons.

Problem Two: A radar pulse is a finite packet of energy due to the cut off of transmission -- the trailing edge.

If we put the two problems together, it is clear to see why the terahertz freq is -- at this time -- unsuitable for long range radar applications.

The longer the pulse, the more energy is in the pulse which will give the pulse only marginal resistance to atmospheric interference, but the time markers, the leading and trailing edges, would be wider. The result is REDUCTION OF ACCURACY of these major target resolutions:

- Range
- Distance
- Heading
- Altitude
- Aspect angle

The shorter the pulse, the greater the accuracy of the above target resolutions, but precisely because a pulse is a finite packet of energy, less energy means greater vulnerabilities to atmospheric phenomenons, and this is not yet adding in Problem One as native to the terahertz freqs.

The longer the pulse, the greater the TACTICAL need for longer transmission periods for the radar computer to work, but this would give the J-20's position away, which defeats the purpose of 'stealth'. The shorter the pulse, the greater the atmospheric losses, thereby giving the J-20 near useless radar vision. Low radar observability is preserved, but at the expense of TACTICAL combat utility.

The problem with these fanboy-ish articles is that people are informed only of the theoretical benefits without educating them of the background information. Technically oriented articles, like the IEEE source, are considered too boring to read thru.

So absolutely yes, put a terahertz radar on the J-20.

 

[Gomig-21]

Indeed, however I'm surprised that the WS-10 also uses this unique system by the AL-31-series to dump fuel via the AB ... as far as I know no other engine (esp. no Western one) has this too.

As opposed to what, dump and burn?

 

[Safriz]

J-20 prototype 2021 spotted with WS-10B engine.

 

[Figaro]

J-20 prototype 2021 spotted with WS-10B engine.

These are old pictures and have been postesd before ...

 

[Deino]

As opposed to what, dump and burn?

No, You got me wrong or you are misinformed: Each aircraft has a system to dump fuel in case of emergency.

My point is that Western types use other methods (on the wings, tail or under the fuselage) to dump fuel and none does it thru the afterburner as it does the Russian AL-31F series ... and the WS-10.

Here Su-30MKK

Here a J-10

... but the JH-7 has a system thru the wings:

 

[Gomig-21]

No, You got me wrong or you are misinformed:

I did misunderstand you, and not sure why since it was pretty clear what you were saying. Must've been too much PDF participation in one day. That tends to turn the brain into mush after a few hours.

Each aircraft has a system to dump fuel in case of emergency.

My point is that Western types use other methods (on the wings, tail or under the fuselage) to dump fuel and none does it thru the afterburner as it does the Russian AL-31F series ... and the WS-10.

I had this discussion many years ago with a former USAF F-15 pilot back in the 1980's who used to visit another forum we were on and was a treasure trove of information, and a great guy as well. He mentioned the concept that the USAF goes by when it comes to dumping fuel from its aircraft because of atmospheric and environmental concerns, even though fuel released at these altitudes is vaporized into gas and never reaches the ground to pose any threat, the idea was more that some were questioning whether the effectiveness of actually burning it off by using a fuel dump & burn (like the famous F-111 and I believe the F-14 did as well) was better overall, or just dumping it which turns out was actually much faster and obviously easier on the engines. It was a great bit of information I wish the forum was still on to look back at the details of the convo, but sadly it isn't.

A couple of points on your examples; despite aircraft such as the F-18 Super Hornet having fuel dumping outlets on the top of both its vertical stabilizers and the F-35 outlet is somewhere under the wings (or even just the port wing), the one in the Eurofighter 2000 is claimed by some to not necessarily be a fuel-dump outlet and that the EF does not have fuel dumping outlets, but that one on the tail fin is rather a "reheat drain."

When reheat is cancelled, there’s a temporary over-pressure caused by unburnt fuel (accumulated in the jet pipe, upstream of the nozzles, after being ingested by the fuel injectors when the afterburner igniter is no longer functioning) that is automatically relieved by venting some 30 Kg (66 Lbs) of fuel through valves located underneath the jet pipe.

Read more at https://theaviationist.com/tag/fuel-dumping/#zxKwd4hT3ZmxOjDY.99

The concept is alleged to be similar to what the Tornado does. The Tornado's fuel dumping outlet is located at the top of the tail fin but its reheat drain system is under the nozzles.

This is a separate process from fuel dumping but supposedly the EF does not have fuel dumping (which I do find hard to believe and is it possible?) and that what it's actually doing when you see fuel released from the top of the V-stab is this reheat draining process.

The Rafale also has an interesting "fuel transfer" process it goes through. There was a thread about that during the Dubai air show when the Rafale demo was performing a negative G maneuver and as it was pulling out of that negative G, it released a bit of fuel from the AB pipe in the starboard nozzle which temporarily ignited by the hot gases and then dissipated. The commentator described it and it was pretty interesting which adds a bit more complexities to all this fuel dumping processes that are in all these different types of aircraft.

 

[onebyone]

China J-20 stealth jets on training ops in Tibet

 

[Deino]

China J-20 stealth jets on training ops in Tibet

Pardon, but AFAIK all images are ether from the PLAAF's anniversary parade or from Zhuhai.