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Chengdu J-20 5th Generation Aircraft News & Discussions

SomeGuy

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Fact: Neither the T-50 nor the J-20 are ever going to match the F-22 for overall stealth simply because they lag behind in the field. Because of which both designs are looking to build their strengths in certain areas ahead of the F-22. The T-50 for eg is relying on being a better air combat fighter than the F-22 and try to get close enough to engage it. The J-20 is looking to simply scoot past the F-22 to get at the targets which are being defended.
If that were the case then the J-20 shouldn't even have canards since canards can adversely affect stealth and make it a lot harder for the J-20 to 'sneak' by.

I read in an article on this forum a while ago that the reason it has canards is the result of a conscious decision by the designers to enable the J-20 to be highly manoeuvrable even though a high performance engine isn't available at the time.

The current Shaping on the J-20 or rather the stealth efforts are different to the T-50. The T-50 looks more to be a compromise for a low rcs in the front 200 sphere while the J-20 will probably present a lower frontal RCS than the T-50. In air combat, if high boresight missiles are taken out of the mix, both the T-50 and F-22 will eat the J-20 for lunch.
Where is the data to support this conclusion?
The raptor is the most advanced fighter in service, yet even it is not invincible - recall the exercises between Raptor & Typhoon/Rafale, where the typhoons were able to get the upper hand, and the Rafales were able to hold their own

However, the J-20 may have a high instantaneous turn rate courtesy of the delta and huge canards which will allow it to take its pot shots at either fighter should they face an encounter.
That, and the two 180kN thrust vectoring WS-15 engines in the production model will make it a highly manoeuvrable fighter.

Moreover, the J-20's recent reveal of the WVR aam missile bays seems to suggest a philosophy of relying on the missiles IR seeker knowing that it will not be able to get a radar lock on a stealth system. Which is why I further support the idea that the J-20 is not looking to engage either fighter in WVR unless it really has to.
All stealth aircraft are designed to deny the enemy from getting a radar lock, that is the whole point of stealth.
The F-22 & PAK-FA will also have similar difficulty locking the J-20 from distance and vice-versa.
The fact that J-20 has bays for SRAAMs means nothing, F-22 has these bays too and no doubt so will PAK-FA.
 

SQ8

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I actually prefer the Northrop's YF-23 over Lockheed's F-22.

It was 'allegedly' faster and stealthier but the later was chosen because it was more agile. China on the other hand went for canards to give its version of stealth plane added maneuverability.

To me, this suggests that they are not as stealthy as they could have been. Both designs have compromised their stealth for added agility or maneuverability would you not agree?
The YF-23 was more stealthier and faster, moreover it matched the YF-22 in terms of aerodynamics performance.
Why it lost was due to the USAFs then obsession with TVC and more importantly the need to distribute contracts to reliable suppliers. At the time, Boeing and Lockheed were open for contracts and had delivered well on the their previous awarded ones. Northdrop on the other hand was behind schedule and much over budget on the B-2 program.
 

SQ8

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Provide proof showing what sensors and electronics the J-20 has. You know the J-20 more than anybody in China so I would like to know. Because we Chinese want to learn from experts like yourself about what capability the J-20 has.

Can you give me a list of what the sensors and electronics the F-22 has that our inferior J-20 don't have?
Just for comparison.

No need to threaten me because I asked a couple of tough questions. I want to learn from anyone that has seen the sensors and electronics of the J-20.
You asked no question at all, all you did was continue on the sarcasm line as you are now and have yet to actually ask intelligent questions. Moreover, you did not bother to read the post or are so stuck in your reactionary thought process loop that you fail to see these sentences.
Which brings us to sensors and electronics on the J-20 which re an unknown but with its huge nose it is likely it could hold an excellent long range and powerful AESA package(provided the reliability and sophistication of Chinese electronics manufacturing matches it) that would allow it to engage at fairly long ranges and(if the Chinese crack the LPI equation) be able to target and kill High Value assets like AWACS and ELINT assets without their escorts having time to react.

If that were the case then the J-20 shouldn't even have canards since canards can adversely affect stealth and make it a lot harder for the J-20 to 'sneak' by.

I read in an article on this forum a while ago that the reason it has canards is the result of a conscious decision by the designers to enable the J-20 to be highly manoeuvrable even though a high performance engine isn't available at the time.



Where is the data to support this conclusion?
The raptor is the most advanced fighter in service, yet even it is not invincible - recall the exercises between Raptor & Typhoon/Rafale, where the typhoons were able to get the upper hand, and the Rafales were able to hold their own



That, and the two 180kN thrust vectoring WS-15 engines in the production model will make it a highly manoeuvrable fighter.



All stealth aircraft are designed to deny the enemy from getting a radar lock, that is the whole point of stealth.
The F-22 & PAK-FA will also have similar difficulty locking the J-20 from distance and vice-versa.
The fact that J-20 has bays for SRAAMs means nothing, F-22 has these bays too and no doubt so will PAK-FA.
As I said before, please read the post carefully to see what the content suggests.
The Typhoon and Rafale both use algorithms to minimize the reflectivity of their canards against emitters. By analyzing where the emitter is originating from and using that to position the canards for minimum exposure. There is a publication out by Chinese researchers on exactly that and some searching lead to it. If the Canards are soo poor for stealth then the J-20 isnt a stealth aircraft at all is it? But you state later that it is.. would you please decide what you want to say

Now, the canards do make it maneuverable than most 4th gen fighters but they do not make it better than the F-22 or T-50 in that regard. We have yet to see the TVC engine and considering the pace of Chinese engine development we are unlikely to see it for a while(hopefully sooner).
Regarding your claims on the Typhoons please have a look at this article before jumping on what you may have read here or there.
F-22 vs Eurofighter BFM in Alaska | The DEW Line

The Typhoons were stripped of their external fuel tanks and slicked off as much as possible before the encounter with the Raptors, says Grune, who adds that in that configuration, the Typhoon is an “animal”.
A few weeks after I returned from Alaska, I touched base withthe 3rd Wing again. “Idid review the HUD footage, a lot of gun shots from the F-22′s to theEurofighters and not a whole lot coming back,” one Raptor pilot told me.
So apparently, it is simply a case of which pilot accounts would you trust?
Read this one for eg.
http://www.defence.pk/forums/pakistan-air-force/124858-pafs-exercises-around-world.html#post2024338

As for SRAAM comment, you clearly did not understand the post at all.IR Missiles can be slaved to the radar or can operate uncaged to scan and seek targets. The F-35 for eg will have LOAL(lock on after launch) available or it can lock on via radar and pass that data to the seeker so that once the missile leaves the aircraft it knows where to look. Thus, the aircraft does not spike its RCS due to the weapon bay opening for too long. The J-20's system looks more focused on being able to carry the missile outside of the bay to allow the seeker to acquire the target all on its own without needing the radar cue. Can the F-22's, T-50's, F-35's bays not do so? perhaps.. but the J-20's are the only ones that look designed with this aspect in mind. i.e they are not looking for a stealthy close in fight at all.
 

Obambam

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The YF-23 was more stealthier and faster, moreover it matched the YF-22 in terms of aerodynamics performance.
Why it lost was due to the USAFs then obsession with TVC and more importantly the need to distribute contracts to reliable suppliers. At the time, Boeing and Lockheed were open for contracts and had delivered well on the their previous awarded ones. Northdrop on the other hand was behind schedule and much over budget on the B-2 program.
It's a shame because YF23 was a great looking bird. But for air superiority with stealth characteristics and from a punctuality perspective, they have chosen the correct plane. They weren't looking for a true stealth bomber afterall.

I think future aerial warfares will be about stealth drones. Do you agree?
 

gambit

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IMHO canards don't contribute much energy return at all.
Wrong. Based upon what standards to qualify as 'much'?

They are essentially a pair of airfoils that are parallel to the planform during interception missions. Only when they actuate do they generate some RCS, by which time the aircraft would probably be in close range and stealth would not matter much anyways. The F/A-XX proposal had canards in the same style as J-20.
Wrong. This is one of the biggest misconception about flight controls avionics. You have no credible TECHNICAL support for the argument that canards are static at certain flight configs and dynamic at others. Does that mean they cannot be designed to be static at certain flight configs? Yes, they can be, such as weight-on-wheels (WOW) situation...



For the above, the Gripen's canards are fixed to act as speedbrakes during landing. The logic is enabled (not active) when landing gear handle is down, speedbrake switch to 'ON', and weight IS NOT on main and nose gear. The logic is un-enabled if the pilot changes his mind and raise the landing gear handle up. But assuming the landing gear handle is down and speedbrake function is 'ON', the logic then becomes active when there is WOW on both main and nose gear. The canards will deflect to a LE down degree as dictated by the brake system engineer to be safest for the aircraft and braking system longevity. By the way, this is a superior method for slowing down a landing aircraft than using drag chute. The drag chute method is simple but maintenance wise it is cumbersome.

But for normal flight, if the canards are designed to be active flight control members, they will be exhibiting movements that will not be visible from afar using cheapo video recording devices such as cell phone cameras. Any pilot who has formation flying experience, which pretty much includes 99.999% of that demographic, will tell you that horizontal stabs and ailerons do move in straight/level flight, especially the horizontal stabs, of which the canards are members of that flight controls avionics sub-group.

As for the argument that the J-20's canards are on the same plane as the main wings...



They are not. Their ROOTS may be and indeed they are. But canards themselves are angled like the Rafale's and in RCS controls regarding planforming and alignment, any deviation increases the odds of unpredictable edge diffraction dynamics with nearby structures.

This has been discussed before and conveniently discarded, of course. The argument that the J-20's canards are static in level flight is indicative of ignorance of stability control principles in flight controls avionics, especially in a pitch unstable design with necessary fly-by-wire capability, and presented to deflect the legitimate criticism of the canards in terms of RCS contributorship. That does not mean it cannot be done but until we have the J-20's flight controls avionics engineer lead himself saying so, the default position is that the canards are active flight controls members.
 

gambit

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I will assume it is more a software issue than raw computerpower. You need to know what to put into the computers. After all both India and China got supercomputers. It cant be just about computerpower.
It is both. Can you use a Cray to do: 2+2=4? Yes. It would be grossly overkill, but there is no doubt your hardware will be capable of doing 2+2=4.

I will put it this way to relate to the subject: Software is like wanting X information. Hardware is like having the capability to get X.

Wanting and getting are not the same thing.

The RCS predicting guys says to you: According to our math, if the target maneuvers this way, we would gain 10db in returns but if the target maneuvers the other way, we would lose 30 db in returns and we need you to keep track of both figures.

You, the hardware guy, would need to design and build the necessary equipment for what the RCS guys want. If you are designing a ground radar station, you are not as limited to what you can do in comparison to designing a radar for a missile, which has nosecone dimensions limitations, the missile's body have far less internal volume for your data processing support, and many more limitations.

The same problem applies if you are shaping. If your body maneuvers this way and gain 10 db in returns for the seeking radar and lose 30 db if maneuvers the other way, then you need to re-shape your body so that it will lose 30 db no matter what maneuver.

RCS controls goes this way:

- Prediction
- Modeling
- Measurement

You can reverse the first two items, but measurement remains the final word. If you do not have adequate computational power to support whatever the software want to do, whether you are trying to detect a low radar observable target or trying to shape a body to become a low radar observable target, you will never achieve your goal of creating a 'stealth' aircraft or detecting one.
 

sincity

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China already decide to build their stealth fighter with canard configuration. No point to discuss whether canard will reduce the stealthy of J20. All your opinion on the J20 have no impact or added value to the production of J20.
 

That Guy

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It's a shame because YF23 was a great looking bird. But for air superiority with stealth characteristics and from a punctuality perspective, they have chosen the correct plane. They weren't looking for a true stealth bomber afterall.

I think future aerial warfares will be about stealth drones. Do you agree?
The eventual goal of every army is to remove the human portion of the army. So what if a drone gets shot down? It's not like anyone died, right? And that's exactly what the air force is looking for.
 

ice bomb

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Provide proof showing what sensors and electronics the J-20 has. You know the J-20 more than anybody in China so I would like to know. Because we Chinese want to learn from experts like yourself about what capability the J-20 has.

Can you give me a list of what the sensors and electronics the F-22 has that our inferior J-20 don't have?
Just for comparison.

No need to threaten me because I asked a couple of tough questions. I want to learn from anyone that has seen the sensors and electronics of the J-20.
Hmm, how about the engine for starter? You are still running on russian engines from the 80s.
 

by78

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Interesting... It says the J-10B is equipped with Gen 1.5 AESA. I wonder what the Gen 1.0 AESA looks like. It probably never made it to production.
 

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