Chengdu J-20 5th Generation Aircraft News & Discussions

[gambit]

As a Mechanical engineer and a lifelong Formula 1 fan I do have many questions regarding changing area of an Inlet of an engine (let alone a DSI one on a stealth aircraft where you require a very good engine efficiency to keep IR signature low too) and I enjoy your posts on these things too as they are very informative. Just saying we are never going to get the answers of all these questions

If you like F1 racing, then you have at least a cursory understanding of the aerodynamics involved in those cars. Me ? Bikes. Motorcycles are aerodynamic disasters.

One thing more about variable DSI. What happens to RCS of J-20 as its DSI changes shape. I mean we talk all the time how RCS suddenly increases when the weapon bay is opened and Serbs even claim the change in RCS was just what they needed to bring F-111 down. Can similar thing happens with a variable DSI ??

Let us assume that the claim of a variable DSI bump is real and installed in the jet.

If you alter the physical characteristics of a structure, the behaviors of the signal waves changes. This have been mathematically formalized by Petr Ufimtsev whose textbook I have on my shelf. I doubt that the changes produces by the shapeshifting DSI bump is as dramatic as the opening of a weapons bay, but signals leaving the DSI bump as it changes its shape and dimension would produce different behaviors when interacts with nearby structures, which would affect final RCS.

It is not " Can similar thing happens with a variable DSI ?? " But similar things WILL happen with a variable DSI bump system. These are the laws of physics that not even China can violate.

Will final RCS increase ? Yes, it will. How much to raise the J-20 above the minimum threshold ? This is where EM anechoic chamber testing is needed and just like the US with our 'stealth' platforms, China is not going release any EM anechoic chamber testing data of the J-20. But shapeshifting the DSI bump will influence final RCS.

This is why it is so entertaining debating the J-20's supporters on this forum. They are clueless on how their claims for the J-20 is consistently -- inconsistent. They consistently do not perform even basic research.

They claim that the J-20's all moving rudders -- vertical stabilators -- are superior to the F-22's rudders. Never mind that the US have the SR-71 with all moving vertical stabs, which should at least hint that the F-22 do not NEED all moving vertical stabs. All moving vertical stabs affects final RCS because you essentially have giant moving reflecting plates. The J-20's engineers are not stupid. They know. But the J-20 needs all moving vertical stabs. So the J-20 supporters essentially changed the laws of physics to say that giant moving plates do not affect Ufimtsev's maths.

Now the J-20's supporters claims that while the F-22's conventional inlet diverter plates are negative to RCS, the J-20's shapeshifting DSI bumps have no effects at all. This conclusion is done with merely using one's eyeballs.

 

[The Eagle]

Happy Chinese New Years to all PDF members!

Same to you and all the Chinese Friends.

 

[帅的一匹]

If you like F1 racing, then you have at least a cursory understanding of the aerodynamics involved in those cars. Me ? Bikes. Motorcycles are aerodynamic disasters.


Let us assume that the claim of a variable DSI bump is real and installed in the jet.

If you alter the physical characteristics of a structure, the behaviors of the signal waves changes. This have been mathematically formalized by Petr Ufimtsev whose textbook I have on my shelf. I doubt that the changes produces by the shapeshifting DSI bump is as dramatic as the opening of a weapons bay, but signals leaving the DSI bump as it changes its shape and dimension would produce different behaviors when interacts with nearby structures, which would affect final RCS.

It is not " Can similar thing happens with a variable DSI ?? " But similar things WILL happen with a variable DSI bump system. These are the laws of physics that not even China can violate.

Will final RCS increase ? Yes, it will. How much to raise the J-20 above the minimum threshold ? This is where EM anechoic chamber testing is needed and just like the US with our 'stealth' platforms, China is not going release any EM anechoic chamber testing data of the J-20. But shapeshifting the DSI bump will influence final RCS.

This is why it is so entertaining debating the J-20's supporters on this forum. They are clueless on how their claims for the J-20 is consistently -- inconsistent. They consistently do not perform even basic research.

They claim that the J-20's all moving rudders -- vertical stabilators -- are superior to the F-22's rudders. Never mind that the US have the SR-71 with all moving vertical stabs, which should at least hint that the F-22 do not NEED all moving vertical stabs. All moving vertical stabs affects final RCS because you essentially have giant moving reflecting plates. The J-20's engineers are not stupid. They know. But the J-20 needs all moving vertical stabs. So the J-20 supporters essentially changed the laws of physics to say that giant moving plates do not affect Ufimtsev's maths.

Now the J-20's supporters claims that while the F-22's conventional inlet diverter plates are negative to RCS, the J-20's shapeshifting DSI bumps have no effects at all. This conclusion is done with merely using one's eyeballs.

When J20 move its stabilizer, it must have entered into dogfight! If it enters into a dogfight, who cares about RCS? As to the RCS of the shapeshifting DSI, our scientist must have calculate it. If you are Smarter than our engineer, I invite you to be the chief of AVIC.

 

[Asoka]

Somebody insists that J-20's TVC nozzle tilt like or look like that of the Flanker's, when not activated. Let me remind everybody that TVC nozzles could look very different, depending on the maturity of the technology and its intended usages.


This is the British Harrier's TVC Nozzle. It got four, two on each side.

This is the USSR's Yak-38 Nozzle. It got two lifting fans at the front, one TVC nozzle at the back.

This is the Russian Yak-141 TVC Nozzle. In the 1990's, LockeedMartin brought the TVC technology and used it on F-35. And China brought it's R79-v300 engine technology and used it on WS-15.

The X-31 technology demonstrator. With this simple paddle like TVC, X-31 beat F/A-18 64 times out of 66 in dogfights.

This is Su-27's enormous 2D-TVC Nozzle demonstrator. No wonder, it was not successful. It must weight over a ton.

This is the F-15S/MTD. it's much better than the Su-27's.

This is F-22's 2D TVC Nozzle. It's matured, but still pretty heavy.

 

[Deino]

Ohh come on ... but all have in common You see that tilt or at least in the 2D nozzles, You see moving parts !

But You surely will us, that this mystical super-duper hyper-powerful engine surely needs only a much smaller angle to achieve the same effect and we are only too blind or unwilling to notice?

Deino

 

[Asoka]

This is Russian Su-37's TVC Nozzle. Someone has insisted that unless the Chinese TVC must look like that, it's no TVC. Notice, the last two sections could tilt. As a result, it's tilting section is much longer and has a much greater tilting angle than the next several TVC, which tilts only the last section.

This is the F-16/MATV. Notice only the last section of the Nozzle could tilt.

This is the F-15 Active TVC Nozzle. Notice only the last section could tilt.

This is the Eurofighter Typhoon's TVC Nozzle. Notice also only the last section could move.

And finally this is the Chinese TVC Nozzle, demonstrated in 2005. Like the previous several nozzles, only the last section could tilt.

As we can see, only the Russian's TVC nozzles use the two sections tilting technology. The Chinese, Europeans and American used one section tilting technology.

This is NOT a TVC Nozzle. It's a ostrich burying his head in the sand. It's a metaphor for someone, who insist Reality to fits his imagination, or insist that the Chinese TVC nozzle must look like the Russian's TVC, otherwise, its not TVC, at all . .

 

[Deino]

@Asok, to admit I slowly feel insulted !

It is not, not the slightest way that I am blind, not that my major intention is to downplay Chinese achievements, but You constant overhyping is annoying, far from being realistic and even if You don't want to hear that:

Some day a few fan-boys will cry out loud and huge tears when all the facts are on the table !

But back to the TVC nozzle: no-one said it has to look like a Russian nozzle and all Your comparisons to 4 nozzles on the Harrier, 2 on the Yak-38, that huge boxy one on the Su-27 (which was in fact a testbed for a future bomber !) and the paddles on the X-31 are all off. Only valid are 3D-nozzles like You showed in Your last posts but if You look closely in all images there is an angle noticeable, which is clearly visible ... and in all images on the J-20 never. Not in the air, not on the ground, simply never.

So please don't tell us again as stupid ...

Deino

 

[Asoka]

No intend to insult, just in a light hearted way to remind my PDF friends, that Russian's 3D-TVC is different from other countries' 3D TVC Nozzle, including China's.

No insult is intended. I am sorry. You are not the only one who disagreed with me, in fact, I don't notice anyone else, has agreed with me, that J-20 has TVC nozzle.

This has nothing to do with stupidity.

"You showed in Your last posts but if You look closely in all images there is an angle noticeable, which is clearly visible ... and in all images on the J-20 never. Not in the air, not on the ground, simply never."

I do agreed that the J-20 TVC nozzle moves very slightly compared to Su-37's, and it is never moved on the ground. It's probably locked, when not using. But, as I have shown, only the last section of the Nozzle tilts, so it has a much less range of motion. This is similar to the TVC nozzle of the F-16/MATV, F-15 Active and Typhoon.

The reason that when people think about 3D nozzle, the Su-37's nozzle comes immediately to mind, is because it's much more demonstrated around the world, while the F-16/MATV, F-15 Active TVC nozzle has faded into memory, and Chinese TVC and Typhoon TVC, is not yet operational, or has not publicly demonstrated, much at all.

Ohh come on ... but all have in common You see that tilt or at least in the 2D nozzles, You see moving parts !

But You surely will us, that this mystical super-duper hyper-powerful engine surely needs only a much smaller angle to achieve the same effect and we are only too blind or unwilling to notice?

Deino

Yes, it is a mystery that the Russian TVC has two sections and moves so much, while other country's TVC moves only the last section, thus moves much less.

What is the reason here?

I think moving two sections needs more actuators, more moving parts, less service life, and more frequently maintenance and its much more heavier.

It is reported that the Indian's SU-30MKI's TVC has only 26 hours of activation life before maintenance, while China's could last well over 126 hrs of activation, before maintenance is needed.

Notice, I mean TVC activation hrs here. When its not activated or tilted, during flight, its not activated.

"that this mystical super-duper hyper-powerful engine surely needs only a much smaller angle to achieve the same effect and we are only too blind or unwilling to notice?

I think the Russian 3D TVC is over done, as other 3D TVC nozzles have shown, it don't need that long and complicated to move the plane effectively.

The rudder of a ship is much much smaller than the ship itself and it don't move all that much, yet its able to change the direction of an enormous ship, easily. This is because the rudder, like the TVC Nozzle, is placed at the back of the ship, hence it has a great moment arm to effect the change of direction.

The J-20 TVC is integrated fully into the Fly-By-Wire flight control system. J-20 has many controls surfaces like the Canards, vertical tails, flaps, LEXes, and the TVC nozzle needs only move enough to accomplish the maneuvers.

The J-20 has a 20m long slender body, so the TVC at the tail, creates a huge Moment Arm, to control the plane, when activated.

These simple little paddles-like TVC of X-31, creates enough control or Moment Arm, to beat the F/A-18, 64 out of 66 times, in mock combat.

 

[Asoka]

"You constant overhyping is annoying, far from being realistic and even if You don't want to hear that:
Some day a few fan-boys will cry out loud and huge tears when all the facts are on the table !"

It's all in your head.

While the Chinese Military Aviation progress in the last 20 years is commendable, but it's not all that amazing, compared to other countries.

Considering, the F-22 first flew in the 1991 (J-20, first flew in 2010 or 2011), and is operational by 2006, F-35's F135 engine has over 190kN of power, and its developed in the 1990's (WS-15, +200kN, developed around 2006-2015). US and Russia has demonstrated 3D TVC nozzles in the 1990s (China demonstrated in 2004).

China is still playing catching up in many fields, not the leader yet.

 

[shadows888]

"You constant overhyping is annoying, far from being realistic and even if You don't want to hear that:
Some day a few fan-boys will cry out loud and huge tears when all the facts are on the table !"

It's all in your head.

While the Chinese Military Aviation progress in the last 20 years is commendable, but it's not all that amazing, compared to other countries.

Considering, the F-22 first flew in the 1991 (J-20, first flew in 2010 or 2011), and is operational by 2006, F-35's F135 engine has over 190kN of power, and its developed in the 1990's (WS-15, +200kN, developed around 2006-2015). US and Russia has demonstrated 3D TVC nozzles in the 1990s (China demonstrated in 2004).

China is still playing catching up in many fields, not the leader yet.

who says china is the leader??? there's only two countries that can build operational stealth fighters right now..USA and China.. russia don't count cause the PAK-FA is like 5-10 years from being ready.

 

[grey boy 2]

"You constant overhyping is annoying, far from being realistic and even if You don't want to hear that:
Some day a few fan-boys will cry out loud and huge tears when all the facts are on the table !"

It's all in your head.

While the Chinese Military Aviation progress in the last 20 years is commendable, but it's not all that amazing, compared to other countries.

Considering, the F-22 first flew in the 1991 (J-20, first flew in 2010 or 2011), and is operational by 2006, F-35's F135 engine has over 190kN of power, and its developed in the 1990's (WS-15, +200kN, developed around 2006-2015). US and Russia has demonstrated 3D TVC nozzles in the 1990s (China demonstrated in 2004).

China is still playing catching up in many fields, not the leader yet.

Asok brother, i'm afraid you're fighting a losing battle against all odds, below is the reasons

When calling us fan-boys is no insults at all since none of us has a so-called military professional title bro, NO matter whatever the said professional throw at us on a mission to belittle Chinese military or China along with insults like "Chinese Physics" and the like of "Have you ever been with any military experience" whenever he's running out of arguments is also perfectly "OK"
Naming us as "PDF Chinese" is fine while saying he's a "Vietnamese" which is a fact even he himself has admitted is a "sin" according to dieno
Have you ever saw dieno challenge him or them for constantly trolling us the way he responding the Chinese members here? is degrading any accomplishments regarding Chinese military is perfectly alright as well? WHY?
OR perhaps gambit is the authority thats always right?
Correct me if i was wrong, hopefully i'm not going to get a"negative rating" like last time to voice my opinion against biased moderation, however if thats the case, so be it, let other members to be the judge then
Please continue your "good work" Asok bro, you've all our support

 

[kuge]

perhaps huge trees attract wind?树大招风？ i think it is fine to a healthy debate

 

[kristisipe]

Asok brother, i'm afraid you're fighting a losing battle against all odds, below is the reasons

When calling us fan-boys is no insults at all since none of us has a so-called military professional title bro, NO matter whatever the said professional throw at us on a mission to belittle Chinese military or China along with insults like "Chinese Physics" and the like of "Have you ever been with any military experience" whenever he's running out of arguments is also perfectly "OK"
Naming us as "PDF Chinese" is fine while saying he's a "Vietnamese" which is a fact even he himself has admitted is a "sin" according to dieno
Have you ever saw dieno challenge him or them for constantly trolling us the way he responding the Chinese members here? is degrading any accomplishments regarding Chinese military is perfectly alright as well? WHY?
OR perhaps gambit is the authority thats always right?
Correct me if i was wrong, hopefully i'm not going to get a"negative rating" like last time to voice my opinion against biased moderation, however if thats the case, so be it, let other members to be the judge then
Please continue your "good work" Asok bro, you've all our support

You are exactly right.

 

[Beast]

No intend to insult, just in a light hearted way to remind my PDF friends, that Russian's 3D-TVC is different from other countries' 3D TVC Nozzle, including China's.

No insult is intended. I am sorry. You are not the only one who disagreed with me, in fact, I don't notice anyone else, has agreed with me, that J-20 has TVC nozzle.

This has nothing to do with stupidity.

"You showed in Your last posts but if You look closely in all images there is an angle noticeable, which is clearly visible ... and in all images on the J-20 never. Not in the air, not on the ground, simply never."

View attachment 372135

View attachment 372136

I do agreed that the J-20 TVC nozzle moves very slightly compared to Su-37's, and it is never moved on the ground. It's probably locked, when not using. But, as I have shown, only the last section of the Nozzle tilts, so it has a much less range of motion. This is similar to the TVC nozzle of the F-16/MATV, F-15 Active and Typhoon.

The reason that when people think about 3D nozzle, the Su-37's nozzle comes immediately to mind, is because it's much more demonstrated around the world, while the F-16/MATV, F-15 Active TVC nozzle has faded into memory, and Chinese TVC and Typhoon TVC, is not yet operational, or has not publicly demonstrated, much at all.



Yes, it is a mystery that the Russian TVC has two sections and moves so much, while other country's TVC moves only the last section, thus moves much less.

What is the reason here?

I think moving two sections needs more actuators, more moving parts, less service life, and more frequently maintenance and its much more heavier.

It is reported that the Indian's SU-30MKI's TVC has only 26 hours of activation life before maintenance, while China's could last well over 126 hrs of activation, before maintenance is needed.

Notice, I mean TVC activation hrs here. When its not activated or tilted, during flight, its not activated.

"that this mystical super-duper hyper-powerful engine surely needs only a much smaller angle to achieve the same effect and we are only too blind or unwilling to notice?

I think the Russian 3D TVC is over done, as other 3D TVC nozzles have shown, it don't need that long and complicated to move the plane effectively.

The rudder of a ship is much much smaller than the ship itself and it don't move all that much, yet its able to change the direction of an enormous ship, easily. This is because the rudder, like the TVC Nozzle, is placed at the back of the ship, hence it has a great moment arm to effect the change of direction.

The J-20 TVC is integrated fully into the Fly-By-Wire flight control system. J-20 has many controls surfaces like the Canards, vertical tails, flaps, LEXes, and the TVC nozzle needs only move enough to accomplish the maneuvers.

The J-20 has a 20m long slender body, so the TVC at the tail, creates a huge Moment Arm, to control the plane, when activated.

These simple little paddles-like TVC of X-31, creates enough control or Moment Arm, to beat the F/A-18, 64 out of 66 times, in mock combat.
View attachment 372188

Hi Asok, there is no need to be apologetic for your well research and documented post. Even your description of somebody so called behaving like an ostrich is highly justify. I see little flaw in your research. I think we are getting very close to solved this mysterious engine install on operational J-20 soon.

 

[Asoka]

Hi Asok, there is no need to be apologetic for your well research and documented post. Even your description of somebody so called behaving like an ostrich is highly justify. I see little flaw in your research. I think we are getting very close to solved this mysterious engine install on operational J-20 soon.

Thanks for your support, Beast. It's very heart warming.

Give some respect to my "opponents" reflects upon my character, not theirs. Be nice to other people ,while still being argumentative, is my new year resolution, and my promise to my wife.

I think China will officially roll out the J-20, along with a announcement what engine J-20 is using, once a regiment or two is in the service.

Asok brother, i'm afraid you're fighting a losing battle against all odds, below is the reasons

When calling us fan-boys is no insults at all since none of us has a so-called military professional title bro, NO matter whatever the said professional throw at us on a mission to belittle Chinese military or China along with insults like "Chinese Physics" and the like of "Have you ever been with any military experience" whenever he's running out of arguments is also perfectly "OK"
Naming us as "PDF Chinese" is fine while saying he's a "Vietnamese" which is a fact even he himself has admitted is a "sin" according to dieno
Have you ever saw dieno challenge him or them for constantly trolling us the way he responding the Chinese members here? is degrading any accomplishments regarding Chinese military is perfectly alright as well? WHY?
OR perhaps gambit is the authority thats always right?
Correct me if i was wrong, hopefully i'm not going to get a"negative rating" like last time to voice my opinion against biased moderation, however if thats the case, so be it, let other members to be the judge then
Please continue your "good work" Asok bro, you've all our support

I have been threatened with ban and deletion of all my posts in the last several months, three times, now.

Yet, this Gambit guy, received a clean pass for his outrageous trolling activities. My patience is up with him. His is on my Ignore list.

Your support is very heart warming and very encouraging.

I won't say, we are fighting a 'losing' battle. I would say we are fighting against a strong head wind of entrenched doubts and skepticism, but when did China never faced doubts/laughters/ridicules from the Westerners?.

The challenges and doubts only make me dig deeper and research harder. It doesn't discourage me, a bit.

We are getting fierce resistance is only because we are getting close to the Truth. We are winning. China's engineers and scientists already did their hard works.

China played a brilliant Game of Deception regarding J-20.

US and its allies is stuck with the fat pig, F-35, hopefully 3000 of them, and they foolishly tricked into cancelling their fierce-some F-22.

If China produced at least +500 of the excellent J-20, in the next few years, we will see Peace in our times. We have the DUTY to defend World Peace against the warmongering US Neocons and Neolibs.