Chengdu J-20 5th Generation Aircraft News & Discussions

[vi-va]

try to understand what gambit said

There are three rules in designing a low radar observable body...

- Control of QUANTITY of radiators
- Control of ARRAY of radiators
- Control of MODES of radiation

add the canard can not shield the wing, the wing does shield the canard in example F-22, aircraft follow rules of physics, the flight control system is designed upon calculations based upon the vectors, constraints the aircraft has.

The F-22 was designed with aft tails simply because they are thinner than the wing thus the wing shields the aft tails reducing the quantity of radiators in a head to head engagement and uses the thrust vectoring nozzles to take over the aft tail in trimming flight pitch moment the aircraft has, J-20 simply went that way because well in reality both aft tails and fore tails increase RCS, so they thought they were sacrificing little for higher gains in mobility, something logic, but the tailless aircraft are the most stealthy albeit they requiere complex systems for roll, pitch and yaw control and they might have reduced controlability.

this pictures says all, basically from a front view F-22 only has 4 radiators, two wings and two vertical tails

this is repeated in other stealth aircraft

F-22 use traditional "caret" style inlet. While J-20, F-35 use DSI(Divertless Supersonic Intakes).

None of us has experience on stealthy design. Meaningless discussion.

The issue is less about the canards as flight controls elements as it is about rule one: Control of QUANTITY of radiators.

- Control of QUANTITY of radiators
- Control of ARRAY of radiators
- Control of MODES of radiation

Under radar bombardment, if it reflects, it becomes a 'radiator'.

Because of that, this is how a radar 'sees' any object, in this case, an aircraft...

... A CLUSTER of voltage spikes.

Sophisticated software can recognize patterns of these voltage spikes and tries to categorize the object as a car, a human body, or like above, an aircraft. But for the vast majority of radar systems out there, civilian and military, if there is a discernible cluster against a somewhat stable background, the radar computer will call the cluster a 'target'.

So going back to the canards. If you begins to reduce the QUANTITY of structures that produces those voltage spikes, you will begin to reduce the EM visibility of the cluster, which is the B-2 and the X-36, and finally, the sphere (post 11837) which is the most obedient to the three rules.

Since '09, I have been saying the same thing over and over about the canards -- it is less about the canards than it is about the three rules. A decade passed and it has not taken root in this forum. None of the rules are more or less important than the others. Modify one and you will affect the other two. Like a three legs stool, modify one and you will change how the structure performs under stress. Ten yrs passed and no one proved me wrong considering there are claimed Ph.Ds in this forum.

F-22 use traditional "caret" style inlet. While J-20, F-35 use DSI(Divertless Supersonic Intakes).

None of us has experience on stealthy design. Meaningless discussion.

 

[CIA Mole]

F-22 use traditional "caret" style inlet. While J-20, F-35 use DSI(Divertless Supersonic Intakes).

None of us has experience on stealthy design. Meaningless discussion.


F-22 use traditional "caret" style inlet. While J-20, F-35 use DSI(Divertless Supersonic Intakes).

None of us has experience on stealthy design. Meaningless discussion.

Mr Gambit worked in aerospace?

But based on that figure he showed, wouldn’t the quality of the “radiators” trump the number of radiators? If you got one bad surface that reveals you, you’re screwed anyway no? So maybe the contribution of the j20 canards are trumped by the other radiators?

Overall surface area of plane should also matter?

 

[Su33KUB]

Can someone introduce me to a good reference on stealth design that talks about these things

gambit did a pretty good explanation and he is very right, just let me add there is nothing truly stealthy, nor F-22, J-20 or F-35 just by simple high school physics you can understand stealth. Electromagnetic waves follow the rules the quantum mechanics dictate; radiation is absorbed or radiated upon small pockets of energy, in few words it is impossible to make invisible aircraft 100% all aircraft are detectable, because any material has a limit, some materials can absorb heat for example and only radiated back after the amount of heat excess the amount needed to raise it's temperature one degree so it will radiated or increase its temperature.

However remember light can be adsorbed in example black objects; it can also be reflected, or difracted, most faceting is reflection, most RAM is absorption, most smooth surfaces and planforming is diffraction, you can look for what is light grated diffraction pattern if you want .

AESA radars or yagi antenas use diffraction interference to steer radar waves, well smooth surfaces and planforming allow reflection of light only in one direction.



in few words the number of radiators, can be explained by simply thinking J-20 has a surface like a mirror, its canards send light into a different direction than its engine nacelles or chined nose and fore body, add its ventral fins allow diffraction by interacting with radiation from its wings or vertical tails, it is impossible for any aircraft to be radar invisible, thus all are detectable specially if you had detectors upon different frequencies of electromagnetic waves, UV or infrared are examples.



So i will put it simple, J-20 has canards not because its designers are smarter nor less capable than the F-22 designers, they designed J-20 trying to balance needs, they went for agility by using canards because at high AoA they increase wing lift, simple like that, the canard as gambit said is not inheritable less stealthy if you are illuminating X-36 from behind it is better that aft tails, the problem is many people here are fans that get angry if you tell them some compromises their aircraft have, J-20 for example has relatively speaking a more complex vortex system than F-35, potentially giving it higher lift at high AoA thus potentially better maneuverability.

DSI intakes are not really truly stealthy either too, they are just more economical for aircraft flying bellow Mach 2, radar signature management is not absolute, it is only a way to make it harder and more expensive to your rival detecting you.

Aircraft tactics are designed in a way you take your aircraft weaknesses and strengths either in stealth, speed, mobility, height, etc etc and use the opposition weaknesses to your advantage


from this view the canard will have a very strong radar reflection back to the emitter it will be very easy to detect it for a radar in front of it, of course J-20 does not fly like that, but that gives you an idea nothing is absolutely stealthy only it is harder to detect and more important the one using better tactics will win, to put it simple if well flown J-20 can beat F-35 using the right tactics, and under wrong tactics and more complex radar systems even a F-5 can defeat F-22

 

[vi-va]

gambit did a pretty good explanation and he is very right, just let me add there is nothing truly stealthy, nor F-22, J-20 or F-35 just by simple high school physics you can understand stealth. Electromagnetic waves follow the rules the quantum mechanics, radiation is absorbed or radiated upon small pockets of energy, in few words it is impossible to make invisible aircraft 100% all aircraft are detectable, because any material has a limit, some materials can absorb heat for example and only radiated back after the amount of heat excess the amount so it will radiated or increase its temperature.

However remember light can be adsorbed in example black objects; it can also be reflected, or difrated, most faceting is reflection, most RAM is absorption, most smooth surfaces and planforming is diffraction, you can look for what is light grated diffraction pattern if you want .

AESA radars or yagi antenas use diffraction interference to steer radar waves, well smooth surfaces and planforming allow reflection of light only in one direction.



in few words the number of radiators, can be explained by simply thinking J-20 has a surface like a mirror, its canards send light into a different direction than its engine nacelles or chined nose and fore body, add its ventral fins allow diffraction by interacting with radiation from its wings or vertical tails, it is impossible for any aircraft to be radar invisible, thus all are detectable specially if you had detectors upon different frequencies of electromagnetic waves, UV or infrared are examples.



So i will put it simple, J-20 has canards not because its designers are smarter nor less capable than the F-22 designers, they designed J-20 trying to balance needs, they went for agility by using canards because at high AoA they increase wing lift, simple like that, the canard as gambit said is not inheritable less stealthy if you are illuminating X-36 from behind it is better that aft tails, the problem is many people here are fans that get angry if you tell them some compromises their aircraft have, J-20 for example has relatively speaking a more complex vortex system than F-35, potentially giving it higher lift at high AoA thus potentially better maneuverability.

DSI intakes are not really truly stealthy either too, they are just more economical for aircraft flying bellow Mach 2, radar signature management is not absolute, it is only a way to make it harder and more expensive to your rival detecting you.

Aircraft tactics are designed in a way you take your aircraft weaknesses and strengths either in stealth, speed, mobility, height, etc etc and use the opposition weaknesses to your advantage


from this view the canard will have a very strong radar reflection back to the emitter it will be very easy to detect it, of course J-20 does not fly like that, but that gives you an idea nothing is absolutely stealthy only it is harder to detect and more important the one using better tactics will win, to put it simple if well flown J-20 can beat F-35 using the right tactics, and under wrong tactics and more complex radar systems even a F-5 can defeat F-22

All 5th gen fighter jets including J-20, F-22 and F-35 can only control RCS in a very narrow angle, optimize for a certain range of bandwidth. @gambit theory is over simplified, and his theory can NOT justify F-22 is more stealthy than J-22 at all. F-22 use traditional "caret" style inlet, while J-20, F-35 use DSI(Divertless Supersonic Intakes). Base on @gambit theory, "caret" style inlet in the straight forward angle has maximized radiation reflection. It's nonsense.

In real battle, none of those 5th gen fighter will use their radar freely, instead electronic silence in most of the time. Electronic warfare including infrared detection is the key. Air situation is provided by AEW&C(Airborne early warning and control) system. Using radar without air situation is suicidal, no matter it's 4th or 5th gen. Your enemy electronic warfare will detect you from 500 kilometers away or even further.

None of us has real experience on stealthy design. Meaningless discussion base on delusion, just some fanboy's fantasy.

 

[Su33KUB]

All 5th gen fighter jets including J-20, F-22 and F-35 can only control RCS in a very narrow angle, optimize for a certain range of bandwidth. @gambit theory is over simplified, and his theory can NOT justify F-22 is more stealthy than J-22 at all. F-22 use traditional "caret" style inlet, while J-20, F-35 use DSI(Divertless Supersonic Intakes). Base on @gambit theory, "caret" style inlet in the straight forward angle has maximized radiation reflection. It's nonsense.

In real battle, none of those 5th gen fighter will use their radar freely, instead electronic silence in most of the time. Electronic warfare including infrared detection is the key. Air situation is provided by AEW&C(Airborne early warning and control) system. Using radar without air situation is suicidal, no matter it's 4th or 5th gen. Your enemy electronic warfare will detect you from 500 kilometers away or even further.

None of us has real experience on stealthy design. Meaningless discussion base on delusion, just some fanboy's fantasy.

I do not speak upon my personal opinion, I usually look for scientific reports by experts, in fact i posted a Brazilian research to justify what i posted, furthermore if you have ever read the development history of other stealth aircraft ranging from MiG1.44, Su-47, Japanese shinshin, Turkish new stealth fighter, Europes new 6th generation, PAKFA or even F-35, YF-23 or F-22, you will see all have studied J-20 configuration all absolutely all, in fact F-35 originally had an early configuration like J-20, why then they discarded that version of F-35? because stealth is reduced but agility is improved, the Americans knew that version with canards was going to be more agile than the one with aft tails, now in order to understand why J-20 is like that you have to understand is not because the Chinese designers are not smart, not at all, they always weight advantages and disadvantages, the americans prefer BVR combat over WVR combat, the Russians believe WVR is very likely will be the zone you will need in combat between 5th generation aircraft plus both China and Russia boast they can detect stealth aircraft, the Russians went for agility and speed with just frontal stealth as the main priority and extensive use of jammers and other electromagnetic frequency detectors, China went for similar configuration with slightly less stealth than F-35 but with potentially better maneuverability and bigger weapons bays, they also consider the time they might need to get real 5th generation engines of 16 to 17 thousand kg thrust, they did sacrifice stealth in J-20 intentionally, because up to one point they know stealth is also propaganda and radar technology does catch up so they will need speed agility and avionics, remember China claims to be able to detect F-22 and Russia says the same.

The 6th generation is enhanced stealth so they have deleted canards and aft tails for tailless concepts and some even without vertical stabilizers, why simple they know 5th generations are indeed detectable and even F-117 was retired relatively early because it became obsolete, so he is not wrong, what happens if you need to see in China they weighted advantages and disadvantages and came to the conclusion J-20 is a system that can work with their awacs and radar system and be effective with long range weapons and advanced helmet cueing systems.

Further more tactics are very important using them right they will potentially overcome the weaknesses J-20 has, and believe me all aircraft have weaknesses

 

[vi-va]

I do not speak upon my personal opinion, I usually look by scientific reports by experts, in fact i posted a Brazilian research to justify what i posted, furthermore if you have ever read the development history of other stealth aircraft ranging from MiG1.44, Su-47, Japanese shinshin, Turkish new stealth fighter, Europes new 6th generation, PAKFA or even F-35, YF-23 or F-22, you will see all have studied J-20 configuration all absolutely all, in fact F-35 originally had an early configuration like J-20, why then they discarded that version of F-35? because stealth is reduced but agility is improved, the americans new that version with canards was going to be more agile than the one with aft tails, now in order to understand why J-20 is like that you have to understand is not because the Chinese designers are not smart, not at all, they always weight advantages and disadvantages, the americans prefer BVR combat over WVR combat, the Russians believe WVR is very likely will be the zone you will need in combat between 5th generation aircraft plus both China and Russia boast they can detect stealth aircraft, the Russians went for agility and speed with just frontal stealth as the main priority, China went for similar configuration with slightly less stealth than F-35 but with potentially better maneuverability and bigger weapons bays, they also consider the time they might need to get real 5th generation engines of 16 to 17 thousand kg thrust, they did sacrifice stealth in J-20 intentionally, because up to one point they know stealth is also propaganda and radar technology does catch up so they will need speed agility and avionics, remember China claims to be able to detect F-22 and Russia says the same.

The 6th generation is enhanced stealth so they have deleted canards and aft tails for tailless concepts and some even without vertical stabilizers, why simple they know 5th generations are indeed detectable and even F-117 was retired relatively early because it became obsolete, so he is not wrong, what happens if you need to see in China they weighted advantages and disadvantages and came to the conclusion J-20 is a system that can work with their awacs and radar system and be effective with long range weapons and advanced helmet cueing systems.

Further more tactics are very important using them right they will potentially overcome the weaknesses J-20 has, and believe me all aircraft have weaknesses

@gambit theory is over simplified, and his theory can NOT justify F-22 is more stealthy than J-22 at all. F-22 use traditional "caret" style inlet, while J-20, F-35 use DSI(Divertless Supersonic Intakes). Base on @gambit theory, "caret" style inlet in the straight forward angle has maximized radiation reflection. It's nonsense.

 

[gambit]

None of us has experience on stealthy design. Meaningless discussion.

If what I posted is 'meaningless', then everything you guys said about the J-20 are equally meaningless. Further, this is a military oriented forum, I served, you have not. So what does that make your participation in this forum? How about meaningless?

 

[vi-va]

If what I posted is 'meaningless', then everything you guys said about the J-20 are equally meaningless. Further, this is a military oriented forum, I served, you have not. So what does that make your participation in this forum? How about meaningless?

your theory contradict with your statement.
by your theory, F-22 traditional "caret" style inlet is not stealthy at all.

Your theory has huge flaws and you didn't know it until I pointed it out.

 

[Ultima Thule]

@Deino please control @Su33KUB this thread is only for news and discussion for J-20 not to compare other 5th gen jets with J-20

 

[Deino]

 

[vi-va]

your theory contradict with your statement.
by your theory, F-22 traditional "caret" style inlet is not stealthy at all.

Your theory has huge flaws and you didn't know it until I pointed it out.

@gambit, no further response anymore?

 

[gambit]

your theory contradict with your statement.
by your theory, F-22 traditional "caret" style inlet is not stealthy at all.

Your theory has huge flaws and you didn't know it until I pointed it out.

The real flaws are in your understanding of the principles in the first place, as in post 11837.

So let us see what you really know about designing a low radar observable body...

Q: In theory, what is the first thing a radar engineer is taught about surfaces?

Q: Regarding the three rules...

- Control of QUANTITY of radiators
- Control of ARRAY of radiators
- Control of MODES of radiation

Surface area falls under which?

 

[CIA Mole]

Anyone here wanna help estimate J20 RCS?
http://s1.nonlinear.ir/epublish/book/Introduction_to_RF_Stealth_1891121219.pdf
From Introduction to RF Stealth:

 

[vi-va]

The real flaws are in your understanding of the principles in the first place, as in post 11837.

So let us see what you really know about designing a low radar observable body...

Q: In theory, what is the first thing a radar engineer is taught about surfaces?

Q: Regarding the three rules...

- Control of QUANTITY of radiators
- Control of ARRAY of radiators
- Control of MODES of radiation

Surface area falls under which?

The red cycled area is the strongest reflection of F-22 by your theory. What is worst, the reflection direction is straight forward, which should be avoid.

Your rule has huge flaws. Here are the rules I copied from the paper below(page 138), which was published on Journal of Computations & Modelling, vol.4, no.1, 2014, 129-165

In fact, the monostatic or backscatter RCS depends on the following

• Target geometry
• Target material composition, especially for the surface
• Position of radar antenna relative to target
• Angular orientation of target relative to radar antenna
• Frequency of the electromagnetic energy
• Radar antenna polarization.

The aim is always the same: reflect the radar energy to certain, irrelevant directions, and thus keeping the (monostatic) RCS low.

4.2 Radar absorbing materials
4.4 Active cancellation

Low Observable Principles, Stealth Aircraft and Anti-Stealth Technologies
http://www.scienpress.com/Upload/JCM/Vol 4_1_9.pdf

You have no clue what radar absorbing materials J-20 and F-22 used, you don't know what active cancellation technologies J-20 and F-22 used neither. You don't know J-20 and F-22 radar design which is crucial for RCS deduction.

Without all those information above to back your arbitrary statement, your statement that J-20 has larger RCS than F-22 is just delusion.

Your theory worth nothing.

@Deino @notmycolon @Fsjal @Figaro @Su33KUB @pakistanipower @serenity @LKJ86 @S10 @ZeEa5KPul @pkd @lcloo @055_destroyer @siegecrossbow @ZeEa5KPul @JSCh

 

[Ultima Thule]

View attachment 581627

The red cycled area is the strongest reflection of F-22 by your theory. What is worst, the reflection direction is straight forward, which should be avoid.

Your rule has huge flaws. Here are the rules I copied from the paper below(page 138), which was published on Journal of Computations & Modelling, vol.4, no.1, 2014, 129-165

In fact, the monostatic or backscatter RCS depends on the following

• Target geometry
• Target material composition, especially for the surface
• Position of radar antenna relative to target
• Angular orientation of target relative to radar antenna
• Frequency of the electromagnetic energy
• Radar antenna polarization.

The aim is always the same: reflect the radar energy to certain, irrelevant directions, and thus keeping the (monostatic) RCS low.

4.2 Radar absorbing materials
4.4 Active cancellation

Low Observable Principles, Stealth Aircraft and Anti-Stealth Technologies
http://www.scienpress.com/Upload/JCM/Vol 4_1_9.pdf

You have no clue what radar absorbing materials J-20 and F-22 used, you don't know what active cancellation technologies J-20 and F-22 used neither. You don't know J-20 and F-22 radar design which is crucial for RCS deduction.

Without all those information above to back your arbitrary statement, your statement that J-20 has larger RCS than F-22 is just delusion.

Your theory worth nothing.

@Deino @notmycolon @Fsjal @Figaro @Su33KUB @pakistanipower @serenity @LKJ86 @S10 @ZeEa5KPul @pkd @lcloo @055_destroyer @siegecrossbow @ZeEa5KPul @JSCh

Stick to the topic bro @gambit knows for his anti Chinese statements and don't bring F-22 to the topic please bro @viva_zhao