Chengdu J-20 5th Generation Aircraft News & Discussions

[phancong]

they have to choose priorities, stealth imposes many conditions that not always are the best solution for aerodynamics, for example the internal weapons bays make for a much bigger and heavier aircraft if they want to keep space for fuel to put it mildly F-35 weights more than 5 tonnes more than a F-16A, thuis they need a much more powerful engine than a F-100, the F135 is almost 80% more powerful than f100.

the F-35 weighs as much as an F-15 at empty weight, and full max weight, by 1970 standards it is a heavy weight fighter, F-22 weighs almost 6 tonnes more than an F-15 at empty weight.


That requiere much more thrust to offset such constraigns, China unless at this moment they are powering the J-20 with WS-15 with full thrust vectoring nozzles, it has an operational fighter just in name, the J-20 to operate really as a truly F-22 needs engines that can allow a 1 to 1 thrust to weight ratio at normal take off, it has very likely a normal take off of 28-30 tonnes, so minimum a 14 tonnes thrust engine, otherwise that extra weight and stealth requirements need to be reduced, so they simply went the way where they only prioritized stealth in the front of the aircraft, leaving the rear with much less stealth, the ventral fins and canards plus the rounded engine nacelles at the rear of the J-20 are solutions to help the aircraft with all the extra weight and lack of thrust

I'm not a aerospace engineering, you don't have to convince me or tell me how China develop their stealth jet, I'm not interested in knowing the detail you provide. Less stealth or more agile of a jet have no meaningful for me to be more inform.

 

[Ultima Thule]

they have to choose priorities, stealth imposes many conditions that not always are the best solution for aerodynamics, for example the internal weapons bays make for a much bigger and heavier aircraft if they want to keep space for fuel to put it mildly F-35 weights more than 5 tonnes more than a F-16A, thus they need a much more powerful engine than a F-100, the F135 is almost 80% more powerful than f100.

the F-35 weighs as much as an F-15 at empty weight, and full max weight, by 1970 standards it is a heavyweight fighter, F-22 weighs almost 6 tonnes more than an F-15 at empty weight.


That require much more thrust to offset such constraigns, China unless at this moment they are powering the J-20 with WS-15 with full thrust vectoring nozzles, it has an operational fighter just in name, the J-20 to operate really as a truly F-22 counterpart needs engines that can allow a 1 to 1 thrust to weight ratio at normal take off, it has very likely a normal take off of 28-30 tonnes, so minimum a 14 tonnes thrust engine, otherwise that extra weight and stealth requirements need to be reduced, so they simply went the way where they only prioritized stealth in the front of the aircraft, leaving the rear with much less stealth, the ventral fins and canards plus the rounded engine nacelles at the rear of the J-20 are solutions to help the aircraft with all the extra weight and lack of thrust

In network environment like China/Russia have stealth has no value, maybe its work on third world countries like Iraq where was no sophisticated IDS (INTERROGATED DEFENSE SYSTEM) have USA currently skipping stealth tech and their 6th generation jets more relying on electronics (AESA/AVIONICS/ECM/ESM/EW) and speed rather than a true stealth @Su33KUB

Clearly? I have been patient with you but now that you twisted my words, the gloves are off.

Nowhere in my post 11875 'clearly' stated that the DSI 'bump' is bad for 'stealth'.

Over the yrs, a lot of noise were produced by the ignorant about the supposedly 'non-stealthy' classic diverter plate intakes of the F-22 vs the supposedly more 'advanced' diverterless DSI 'bump' on the J-20.

The ignorant, which includes you, usually claimed that the classic diverter plates are bad for 'stealth'. In other words, my comment that you highlighted is actually the opposite of what you twisted of what I said.

This image...

...Is only to show that under most flight conditions, BOTH the diverter plates and the DSI 'bumps' are irrelevant to RCS calculations. Nowhere did I even implied that one is superior to the other.

The liar is YOU.

Oh sir my bad i accept my mistake i didn't fully understand your post pardon me sir

 

[vi-va]

Big difference between you and I...

Stick time...

https://www.urbandictionary.com/define.php?term=Stick Time
Time behind a joystick; flight time, flying time.

I have it. You do not. I have civilian flight training even before my USAF time. My technical understanding of radar detection as a field test engineer was after the USAF. Basically, I designed field tests to detect 'low altitude autonomous flight vehicles' aka 'drones' in both how to detect them and how they can avoid detection.

Bottom line, you know shit.

If you are that good. I hope I can learn something from you. But so far I only see arbitrary statement, not solid proof to back your statement.

 

[Figaro]

Interesting, the J-20 was referred to as China's first "supersonic stealth fighter." So the J-20 can supercruise after all it seems.

 

[gambit]

If you are that good. I hope I can learn something from you. But so far I only see arbitrary statement, not solid proof to back your statement.

Arbitrary? In your ignorance, not mine.

Here we go again...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

If the rules are 'arbitrary', then how do you explain the Lincoln Calibration Sphere in orbit and the B-2? The fact that Lincoln Sphere exists is proof enough. But wait...There is more...

https://www.centurymetalspinning.com/radar-calibration-spheres/

Why is the sphere -- but not the cube or the pyramid or the trapezoid or the cone or whatever -- the ideal calibration body for any radar design?

Because the sphere is the most obedient to Rule One: Control of QUANTITY of radiators.

Look at these...

https://www.popularmechanics.com/mi...-stealth-drone-has-no-moving-surfaces-at-all/
BAE Systems has unveiled a new aircraft design that could be a major advance in stealth technology.

...uses blown air to change direction instead of complex mechanical controls.

https://www.thedrive.com/the-war-zo...hing-wing-technology-will-the-b-21-feature-it
Joints are not good for low observability, and flapping around control surfaces exposing those joints are especially bad. Large, seamless, continuously rounded structures that are edge-aligned to the general aircraft design are best for broadband low observability.

What is the common theme for both attempts to reduce RCS?

Rule Two: Control of ARRAY of radiators

Moving structures affects how EM waves exits a finite body like a wing.

In post 11865 page 791, I asked YOU: In theory, what is the first thing a radar engineer is taught about surfaces?

In theory, the first thing an aspiring radar engineer is taught about surfaces is that it is infinite, whether that surface is on a plane or an edge. Of course, we know such a thing does not exist. All bodies are finite in shape and dimensions. But the reason an EE is trained to calculate on an infinite surface is to eliminate all other influences.

In real life, any body is a finite body and somehow some time an EM wave must leave that body as in Rule Three: Control of MODES of radiation

So now with the two above sources, we have rules two and three in play. A moving structure like an aileron changes its physical relationships -- array -- to other structures. As the EM wave exits the aileron, how or the mode it radiate into free space is important. Rules Two and Three affects each other.

If we can eliminate aileron like how BAE is exploring or by introducing curvatures like how the USAF is experimenting, we becomes more and more obedient to all three rules.

Still think I do not know what I am talking about? Then look at this...

Why is the radome on the Su-27 a rounded conic but the radomes on the F-22, J-20, and PAK-FA have ridges on the sides?

Because of Rule Three: Control of MODES of radiation

In radar detection, there is something called the '10-lambda rule'. To sum it up, lambda ( λ ) is the symbol for wavelength and if the diameter is less than 10-lambda, there will be an effect called the 'creeping wave'...

A radome is not a cylinder but mostly a conic, so that mean eventually, a radar signal will travel around the decreasing diameter of the radome and this is not what we want in a low radar observable design, hence the ridges or chines on the radomes of the F-22, J-20, and the PAK-FA. As the creeping wave travels around the radome, the ridges provided an exit point that will not be detected by the seeking radar on the other side. In this instance, we exploited Rules One and Three to our advantage: we increased the QUANTITY of radiators and altered the MODES of radiation.

And just in case you think I made up this 10-lambda rule, think again...

Look at the names of the authors and city where they came from. You can be quite sure they are non US, eh? Look at the yr of the conference. Look at the intro: >10 λ

Like it or not, the J-20 is less obedient than the F-22 and the F-35 to the three rules. You can take everything I posted so far to any EE professor and I will be proven correct. You are treading into a domain you know nothing about but too arrogant to admit it.

I schooled you, pal.

 

[vi-va]

Arbitrary? In your ignorance, not mine.

Here we go again...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

If the rules are 'arbitrary', then how do you explain the Lincoln Calibration Sphere in orbit and the B-2? The fact that Lincoln Sphere exists is proof enough. But wait...There is more...

https://www.centurymetalspinning.com/radar-calibration-spheres/

Why is the sphere -- but not the cube or the pyramid or the trapezoid or the cone or whatever -- the ideal calibration body for any radar design?

Because the sphere is the most obedient to Rule One: Control of QUANTITY of radiators.

Look at these...

https://www.popularmechanics.com/mi...-stealth-drone-has-no-moving-surfaces-at-all/
BAE Systems has unveiled a new aircraft design that could be a major advance in stealth technology.

...uses blown air to change direction instead of complex mechanical controls.

https://www.thedrive.com/the-war-zo...hing-wing-technology-will-the-b-21-feature-it
Joints are not good for low observability, and flapping around control surfaces exposing those joints are especially bad. Large, seamless, continuously rounded structures that are edge-aligned to the general aircraft design are best for broadband low observability.

What is the common theme for both attempts to reduce RCS?

Rule Two: Control of ARRAY of radiators

Moving structures affects how EM waves exits a finite body like a wing.

In post 11865 page 791, I asked YOU: In theory, what is the first thing a radar engineer is taught about surfaces?

In theory, the first thing an aspiring radar engineer is taught about surfaces is that it is infinite, whether that surface is on a plane or an edge. Of course, we know such a thing does not exist. All bodies are finite in shape and dimensions. But the reason an EE is trained to calculate on an infinite surface is to eliminate all other influences.

In real life, any body is a finite body and somehow some time an EM wave must leave that body as in Rule Three: Control of MODES of radiation

So now with the two above sources, we have rules two and three in play. A moving structure like an aileron changes its physical relationships -- array -- to other structures. As the EM wave exits the aileron, how or the mode it radiate into free space is important. Rules Two and Three affects each other.

If we can eliminate aileron like how BAE is exploring or by introducing curvatures like how the USAF is experimenting, we becomes more and more obedient to all three rules.

Still think I do not know what I am talking about? Then look at this...

Why is the radome on the Su-27 a rounded conic but the radomes on the F-22, J-20, and PAK-FA have ridges on the sides?

Because of Rule Three: Control of MODES of radiation

In radar detection, there is something called the '10-lambda rule'. To sum it up, lambda ( λ ) is the symbol for wavelength and if the diameter is less than 10-lambda, there will be an effect called the 'creeping wave'...

A radome is not a cylinder but mostly a conic, so that mean eventually, a radar signal will travel around the decreasing diameter of the radome and this is not what we want in a low radar observable design, hence the ridges or chines on the radomes of the F-22, J-20, and the PAK-FA. As the creeping wave travels around the radome, the ridges provided an exit point that will not be detected by the seeking radar on the other side. In this instance, we exploited Rules One and Three to our advantage: we increased the QUANTITY of radiators and altered the MODES of radiation.

And just in case you think I made up this 10-lambda rule, think again...

Look at the names of the authors and city where they came from. You can be quite sure they are non US, eh? Look at the yr of the conference. Look at the intro: >10 λ

Like it or not, the J-20 is less obedient than the F-22 and the F-35 to the three rules. You can take everything I posted so far to any EE professor and I will be proven correct. You are treading into a domain you know nothing about but too arrogant to admit it.

I schooled you, pal.

Thank you for your long post. You finally showed me something worth reading. Since you are so superior, can you school me how to explain the red cycled area. Base on your theory, it's not a good design at all.

 

[Su33KUB]

I'm not a aerospace engineering, you don't have to convince me or tell me how China develop their stealth jet, I'm not interested in knowing the detail you provide. Less stealth or more agile of a jet have no meaningful for me to be more inform.

Arbitrary? In your ignorance, not mine.

Here we go again...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

If the rules are 'arbitrary', then how do you explain the Lincoln Calibration Sphere in orbit and the B-2? The fact that Lincoln Sphere exists is proof enough. But wait...There is more...

https://www.centurymetalspinning.com/radar-calibration-spheres/

Why is the sphere -- but not the cube or the pyramid or the trapezoid or the cone or whatever -- the ideal calibration body for any radar design?

Because the sphere is the most obedient to Rule One: Control of QUANTITY of radiators.

Look at these...

https://www.popularmechanics.com/mi...-stealth-drone-has-no-moving-surfaces-at-all/
BAE Systems has unveiled a new aircraft design that could be a major advance in stealth technology.

...uses blown air to change direction instead of complex mechanical controls.

https://www.thedrive.com/the-war-zo...hing-wing-technology-will-the-b-21-feature-it
Joints are not good for low observability, and flapping around control surfaces exposing those joints are especially bad. Large, seamless, continuously rounded structures that are edge-aligned to the general aircraft design are best for broadband low observability.

What is the common theme for both attempts to reduce RCS?

Rule Two: Control of ARRAY of radiators

Moving structures affects how EM waves exits a finite body like a wing.

In post 11865 page 791, I asked YOU: In theory, what is the first thing a radar engineer is taught about surfaces?

In theory, the first thing an aspiring radar engineer is taught about surfaces is that it is infinite, whether that surface is on a plane or an edge. Of course, we know such a thing does not exist. All bodies are finite in shape and dimensions. But the reason an EE is trained to calculate on an infinite surface is to eliminate all other influences.

In real life, any body is a finite body and somehow some time an EM wave must leave that body as in Rule Three: Control of MODES of radiation

So now with the two above sources, we have rules two and three in play. A moving structure like an aileron changes its physical relationships -- array -- to other structures. As the EM wave exits the aileron, how or the mode it radiate into free space is important. Rules Two and Three affects each other.

If we can eliminate aileron like how BAE is exploring or by introducing curvatures like how the USAF is experimenting, we becomes more and more obedient to all three rules.

Still think I do not know what I am talking about? Then look at this...

Why is the radome on the Su-27 a rounded conic but the radomes on the F-22, J-20, and PAK-FA have ridges on the sides?

Because of Rule Three: Control of MODES of radiation

In radar detection, there is something called the '10-lambda rule'. To sum it up, lambda ( λ ) is the symbol for wavelength and if the diameter is less than 10-lambda, there will be an effect called the 'creeping wave'...

A radome is not a cylinder but mostly a conic, so that mean eventually, a radar signal will travel around the decreasing diameter of the radome and this is not what we want in a low radar observable design, hence the ridges or chines on the radomes of the F-22, J-20, and the PAK-FA. As the creeping wave travels around the radome, the ridges provided an exit point that will not be detected by the seeking radar on the other side. In this instance, we exploited Rules One and Three to our advantage: we increased the QUANTITY of radiators and altered the MODES of radiation.

And just in case you think I made up this 10-lambda rule, think again...

Look at the names of the authors and city where they came from. You can be quite sure they are non US, eh? Look at the yr of the conference. Look at the intro: >10 λ

Like it or not, the J-20 is less obedient than the F-22 and the F-35 to the three rules. You can take everything I posted so far to any EE professor and I will be proven correct. You are treading into a domain you know nothing about but too arrogant to admit it.

I schooled you, pal.

thank you gambit, i really learnt something, this really helps to understand J-20 more

 

[LKJ86]

Via @goneless from Weibo

 

[Su33KUB]

View attachment 581889
Via @goneless from Weibo

just from the picture you can see J-20 is around 21+ meters, as I knew, every new picture shows that i was right 21 meters at least

 

[Ultima Thule]

just from the picture you can see J-20 is around 21+ meters, as I knew, every new picture shows that i was right 21 meters at least

J-20 is shorter than Su-27/J-11 series of jet, you fool @Su33KUB

 

[Fsjal]

J-20 is shorter than Su-27/J-11 series of jet, you fool @Su33KUB

Another thing to add is that the Su-27/J-11 is almost 22 meters long. J-20 is only around 20 meters in length, and plus both the J-20s and Flankers are off-centered in the pic. As a result the composition gives the impression that J-20 is as long as the Flanker. A better pic for comparison would be a top view of both J-20 and Flanker side-by-side and center to the picture in order to accurately compare length.

 

[LKJ86]

View attachment 581889
Via @goneless from Weibo

A new video from PLAAF's Weibo:
https://m.weibo.cn/5707057078/4422694227168845

 

[LKJ86]

Via @追风之翎 from Weibo

 

[LKJ86]

Via CCTV and @红色金银潍 from Weibo

 

[gambit]

Thank you for your long post. You finally showed me something worth reading. Since you are so superior, can you school me how to explain the red cycled area. Base on your theory, it's not a good design at all.

It is good enough. The problem with you is that you allowed your nationalistic passion takes over your critical thinking skills. A behavior common to the Chinese members here. And I say that kindly.

Let us take a look at this illustration again since you repeatedly failed to understand it...

Somewhere in those clusters of voltage spikes, there are spikes from doors and windows. But can you see them? Can you distinguish which spike came from which structure? No, you cannot and neither can any radar system, including Chinese ones.

You can call the classic diverter plates as inferior to the DSI 'bump' all you want but in the larger scheme of things, its supposedly 'inferior' design is irrelevant.

There is something called 'interference' and there are two types of interference:

- Constructive
- Destructive

In designing a low radar observable body, we want DESTRUCTIVE interference. It means to cancel out.

https://www.phys.uconn.edu/~gibson/Notes/Section5_2/Sec5_2.htm

Are the signals from the F-22's classic diverter plates canceled out by signals from other structures nearby? Only Lockheed knows.

The diverter plate is not a good design? Only in your delusions. The bottom line is that the F-22's intakes did not matter one whit.

On the other hand, unlike the F-22's intake diverter plates, the J-20's canards are visible most of the time in most flight aspect angles. Their positions on the fuselage do not make possible destructive interference. The canards are CONSTANTLY exposed. So when experts commented about the canards as being negative for 'stealth', they do not comment because they are anti-China but do so from the laws of physics.

The problem for you guys is that I posted these explanations REPEATEDLY since '09. New Chinese members comes and predictably, each of them thinks he posted something new and predictably, each got debunked by me. Just like you got schooled.