Chengdu J-20 5th Generation Aircraft News & Discussions

[DrSomnath999]

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Dr. Somnath, you are mixing apples and oranges in this discussion. Why don't you do a reverse post and claim the J-20 can passively detect a F-22 from over 200 miles away? Of course, a modern radar can passively detect an emitting radar from 200 miles away. Everyone knows that. What is your point?

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oh boy u are trully a fanbouy ,no it cant as F22 wont turn it's radar as it would depend upon passive detection for detection of
J20 so how can j20 aesa radr detect f22 if it doesnt turn on it's radar ,

 

[gambit]

From fifty miles away, the subtended angle of the LITTLE canard gap approaches zero. That's why the stealth penalty should be only about 2% from about 20 miles away.

The subtending of an angle is easy to understand. The Moon subtends a distance of roughly your thumb, when held at arms distance. The Sun is a gazillion times larger than the Moon and yet, it appears the same size in the sky. The subtended angle of an object is a function of size AND distance.

To use the principle of subtending angle, let's say the J-20 canard gap is a few inches if you stand close to it. Let's just say 3 inches. 3 inches from fifty miles away subtends a fraction of a fraction of a fraction of a degree. It's microscopic.

I stand by my estimate that a little canard gap will yield a stealth penalty in the 2 to 3% range. The angle it subtends is simply too small. The extremely small subtended angle can be expressed as a percentage of the entire subtended angle of the J-20 aircraft to yield the conclusion of a 2% effect.

I just don't feel like spending 30 minutes to calculate a precise number. It wouldn't change the minds of the rabid anti-China crowd.

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Dr. Somnath, you are mixing apples and oranges in this discussion. Why don't you do a reverse post and claim the J-20 can passively detect a F-22 from over 200 miles away? Of course, a modern radar can passively detect an emitting radar from 200 miles away. Everyone knows that. What is your point?

I'm trying to make the point that there are indeed minor flaws present on the J-20 Mighty Dragon. There is indeed a slight advantage for a F-22 pilot. I have shown that the advantage is roughly 3 to 5 seconds from twenty miles away, which I believe is operationally useless. Readers are free to make their own independent judgment.

The subtending argument is misleading here.

If we raise the detection threshold to cover most of the airliner's smaller RCS contributors to expose only the major ones, this is how we should compare these various 'stealth' aircrafts. If one aircraft has a structure or combination of structures that raised it above the detection threshold, which is the clutter rejection threshold, it will be detected, tracked, and targeted while the other will be discarded as part of 'clutter'. It does not matter if the disadvantage (or difference) is less than 10pct. If it is above the clutter rejection threshold, it will be focused upon.

 

[SQ8]

well why should we compare a test protype with j20 ,it has no relevance .as Yf22 had many design changes which evolved into
F22 Am i right ???

I fail to see why it has no relevance.. what if the J-20 is also a test prototype which is supposed to evolve into something else?

 

[Firemaster]

The subtending argument is misleading here.

If we raise the detection threshold to cover most of the airliner's smaller RCS contributors to expose only the major ones, this is how we should compare these various 'stealth' aircrafts. If one aircraft has a structure or combination of structures that raised it above the detection threshold, which is the clutter rejection threshold, it will be detected, tracked, and targeted while the other will be discarded as part of 'clutter'. It does not matter if the disadvantage (or difference) is less than 10pct. If it is above the clutter rejection threshold, it will be focused upon.

@ Gambit
Is this image from Skolnik's work?

And shall u please You explain figure2(b)??

 

[DrSomnath999]

I fail to see why it has no relevance.. what if the J-20 is also a test prototype which is supposed to evolve into something else?

then why are we wasting time here by debating tell me ? then we should wait for final production protype when martian can
find out loopholes in pakfa then we can also say the samething as u are saying ,NOw tell me?

 

[SQ8]

then why are we wasting time here by debating tell me ? then we should wait for final production protype when martian can
find out loopholes in pakfa then we can also say the samething as u are saying ,NOw tell me?

First.. The thread is on the J-20.. so ANYONE can discuss the J-20.
Second.. Pak-Fa CAN be compared to the J-20 as a test aircraft ..
Third.. That is a very lame attempt at being cynical..

 

[gambit]

@ Gambit
Is this image from Skolnik's work?

Nope.

And shall u please You explain figure2(b)??

It is a graphical illustration of the various voltage spikes, as how all contributors really are.

 

[DrSomnath999]

First.. The thread is on the J-20.. so ANYONE can discuss the J-20.

so what am i discussing now LCA

Second.. Pak-Fa CAN be compared to the J-20 as a test aircraft ..

so f22 cannot be compared as it is a productioon aircraft & we have to compare only a protype aircaft of yf 23 as it is handicapped
stealth aircraft & Chinese can compare J20 as F22 peer well that's precious

Third.. That is a very lame attempt at being cynical..

well i can understand that very well why r u saying this . i dont want to elaborate it

 

[FairAndUnbiased]

First.. The thread is on the J-20.. so ANYONE can discuss the J-20.
Second.. Pak-Fa CAN be compared to the J-20 as a test aircraft ..
Third.. That is a very lame attempt at being cynical..

J-20 has undergone 62 flight tests in the past year. PAK-FA underwent 3.

DrSomanth999 found many "irregularities" in the J-20 some of which are also present in the F-22.

It is absolutely insane or stupid to think that the much larger gap between fuselage and intakes on the F-22 has zero contribution to RCS while the gap between canards and fuselage on the J-20 puts it above clutter rejection threshold without actual tests, which no one has.

 

[SQ8]

so what am i discussing now LCA

so f22 cannot be compared as it is a productioon aircraft & we have to compare only a protype aircaft of yf 23 as it is handicapped
stealth aircraft & Chinese can compare J20 as F22 peer well that's precious

well i can understand that very well why r u saying this . i dont want to elaborate it

well.. so far your last two posts have involved cheapshots so I am wondering if there is any worth coming down to your level.
Your assumptions on what is allowed or not are all based on your own issues.
Find me one post where I said its Halal or Haram?
Again.. sad to see that you too have inclinations to join the lot which makes low quality posts.

 

[FairAndUnbiased]

Note the gap between fuselage and intakes.

Fortunately it's American. American planes, no matter their flaws, are always faster, stealthier, and far superior to the planes of others. Doesn't need technical explanation. Team USA **** yeah.

 

[gambit]

DrSomanth999 found many "irregularities" in the J-20 some of which are also present in the F-22.

It is absolutely insane or stupid to think that the much larger gap between fuselage and intakes on the F-22 has zero contribution to RCS while the gap between canards and fuselage on the J-20 puts it above clutter rejection threshold without actual tests, which no one has.

Then it is equally insane to make baseless assumptions as to the J-20's low radar observability if it is comparable to the F-22 within any statistical significance. In that case, saying the J-20's RCS is less than 5% to the F-22 is pretty insane.

 

[amalakas]

The subtending argument is misleading here.

If we raise the detection threshold to cover most of the airliner's smaller RCS contributors to expose only the major ones, this is how we should compare these various 'stealth' aircrafts. If one aircraft has a structure or combination of structures that raised it above the detection threshold, which is the clutter rejection threshold, it will be detected, tracked, and targeted while the other will be discarded as part of 'clutter'. It does not matter if the disadvantage (or difference) is less than 10pct. If it is above the clutter rejection threshold, it will be focused upon.

Man here we go again.

Martian2 is slipping more and more into madness. First came the photo of the planform alignment of the J-20 which is I suspect much worse than that of the T-50, then came the arguments about the canards, then instead of silencing his mouth after
been exposed for double standards on the T-50 IRST sensor , he carried on.

The final nail on the coffin is his ability to guest-imate percentages, 2% this , 10% that... man, the collective pride and dignity of all my respected lecturers and professors is going down the drain by me reading what this guy writes.

He gets pleasure from writing "mighty dragon" over and over again, ... I suggest you should write fighting falcon and super hornet and raptor every time you write.
also fulcrum and flanker B etc etc etc ... man ....

i can say one thing for sure, science has taken quite a hit on this thread despite some brave efforts by some to maintain some reasonable scientific level ...

where does one begin with this one?

Martian have you ever been involved with the tech you so easily talk about ?

I will give you an example, a 50 year old design, the venerable MiG-21 (fishbed i think) since you like the nicknames so much, is almost impossible to detect head on from most modern day fighters, even F-16s blk 52+ cannot detect it head on at about 100km or approx 60miles. Do you know what kind of a pain in the butt that is ?

I dare say you have never looked down a radar screen in a fighter plane trying to test the radar for your country's particular terrain and see how it behaves in various modes and what kind of performance it provides in different scenarios.

to you a radar sees all and stealth absorbs all !!!

I got news buddy ... it ain't so !

 

[gambit]

The final nail on the coffin is his ability to guest-imate percentages, 2% this , 10% that... man, the collective pride and dignity of all my respected lecturers and professors is going down the drain by me reading what this guy writes.

But do not forget, his video has over 80k views while we who tried to inject a little bit is scientific integrity into the discussion have no videos therefore our challenges to his nonsense are based upon racism and jealousy.

 

[SQ8]

But do not forget, his video has over 80k views while we who tried to inject a little bit is scientific integrity into the discussion have no videos therefore our challenges to his nonsense are based upon racism and jealousy.

Alright folks.. Think thats enough there.
Those who do KNOW the subjects(Sat in Wave theory class jacked up on caffeine) know what is right and what is wrong.
Those who DONT KNOW the subjects will continue to accept whatever suits their fancy...period.
Its best to make the point.. and move on.