Chengdu J-20 news, pictures, analysis Part III

sferrin

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Blitzo said:
sferrin said:
Did I say "every single twin tail canard"? No. I did not.
Ah good, then you agree that referencing the JAST canard delta proposal and comparing it to Song's aerodynamic proposal (that became J-20) is illogical. Glad that's settled.
Oh, of course. It's completely original. ::)

===

Blitzo said:
In all seriousness, when you said "general configuration" the only logical way to interpret it is to believe that you mean twin tail canard delta configurations.
Hardly. The Mig 1.42 for instance looks very different as do many other past canard deltas.

Canard delta: check
Side Inlets: check
DVI: check
Twin tail: check

Frankly I was astonished you'd even attempt to argue the point. Do they look exactly alike? Obviously not. Does my statement stand? Of course.

"On the other hand, that general configuration was not only in open literature at the time, it was actively being worked in other countries."

The differences are mainly in the details.
 

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PaulMM (Overscan) said:
The fact it retained the canard implies that maneuverability remained of prime importance after 2001. Its an air superiority aircraft with secondary interceptor/strike roles.
As I have written it before hundred of times (doesn't means that it make it more relevant, obviously) I do not think that the big canards are primarily here for maneuverability. There are two points that can explain this choice when you put this back into perspective: lack of structural competences (China had never been before successful in building from scratch its own set of wings) and mission profile (the wide apart large canard and high loaded delta make it easy to trim rapidly (reduced flapping lift) turning this configuration into an efficient sea skimming airframe). Add the lag in stealth design, the easiest way of reverse engineering* something that is not top notch in term of aero technology and you've got the J-20.

*reverse engineering has (nearly) nothing to do with spying and paying bribes to corrupt foreign assets
 

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TomcatViP said:
PaulMM (Overscan) said:
The fact it retained the canard implies that maneuverability remained of prime importance after 2001. Its an air superiority aircraft with secondary interceptor/strike roles.
As I have written it before hundred of times (doesn't means that it make it more relevant, obviously) I do not think that the big canards are primarily here for maneuverability. There are two points that can explain this choice when you put this back into perspective: lack of structural competences (China had never been before successful in building from scratch its own set of wings) and mission profile (the wide apart large canard and high loaded delta make it easy to trim rapidly (reduced flapping lift) turning this configuration into an efficient sea skimming airframe). Add the lag in stealth design, the easiest way of reverse engineering* something that is not top notch in term of aero technology and you've got the J-20.

*reverse engineering has (nearly) nothing to do with spying and paying bribes to corrupt foreign assets
So, if that's your explanation for the J-20's configuration, what do you think about Song Wencong's paper? A bunch of hot air? ::)
 

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LERX are draggy. Canards are Draggy. Delta are draggy. You don't add bigg a to large b and small c just for the fun of it. It's a constraint based equation*. If they had at the time better knowledge for example and blablabla, the J-20 would have been something different. I am sure that the next iteration of Chinese fighter will sport a different configuration. But obviously we would have to wait and see.

*and it's difficult to sum it up in two lines!
 

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TomcatViP said:
LERX are draggy. Canards are Draggy. Delta are draggy. You don't add a to b and c just for the fun of it. It's a constraint based equation. If they had at the time active fluidic ctrl knowledge for example and blablabla, the J-20 would have been something different. I am sure that the next iteration of Chinese fighter will sport a different configuration. But obviously we would have to wait and see.
You forgot to mention tails. Tails are draggy. Oh and also wings that aren’t deltas. Those kinds of wings are draggy too! By your logic there’s no such thing as a maneuverable fighter because no fighter uses active fluidic controls.

Your a+b+c logic also does not hold. Let’s just discard every other factor for drag and just focus on feature count shall we? A small canard adds just as much drag as a large tail. A large aspect ratio LERX adds just as much drag as small one! Never mind other geometries on the plane. The only things that count as draggy are canards, LERXes, and Deltas! This is a nonsensical argument. Drag is determined by the net interaction between the airflow and the whole shape in question, not a few cherry picked parts, treated as categorical variables with all other geometric considerations discarded. The “constraint based equation” is defined by overall shape, not a list of features.
 

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latenlazy said:
TomcatViP said:
LERX are draggy. Canards are Draggy. Delta are draggy. You don't add a to b and c just for the fun of it. It's a constraint based equation. If they had at the time active fluidic ctrl knowledge for example and blablabla, the J-20 would have been something different. I am sure that the next iteration of Chinese fighter will sport a different configuration. But obviously we would have to wait and see.
You forgot to mention tails. Tails are draggy. Oh and also wings that aren’t deltas. Those kinds of wings are draggy too! By your logic there’s no such thing as a maneuverable fighter because no fighter uses active fluidic controls.

Your a+b+c logic also does not hold. Let’s just discard every other factor for drag and just focus on feature count shall we? A small canard adds just as much drag as a large tail. A large aspect ratio LERX adds just as much drag as small one! Never mind other geometries on the plane. The only things that count as draggy are canards, LERXes, and Deltas! This is a nonsensical argument. Drag is determined by the net interaction between the airflow and the whole shape in question, not a few cherry picked parts, treated as categorical variables with all other geometric considerations discarded.
honestly, I laughed at the idea of a J-20 without delta wing, without canards, without LERX.
It'll literally be the central fuselage with tails. It certainly won't be very draggy! ;D

10/10
 

latenlazy

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Blitzo said:
TomcatViP said:
PaulMM (Overscan) said:
The fact it retained the canard implies that maneuverability remained of prime importance after 2001. Its an air superiority aircraft with secondary interceptor/strike roles.
As I have written it before hundred of times (doesn't means that it make it more relevant, obviously) I do not think that the big canards are primarily here for maneuverability. There are two points that can explain this choice when you put this back into perspective: lack of structural competences (China had never been before successful in building from scratch its own set of wings) and mission profile (the wide apart large canard and high loaded delta make it easy to trim rapidly (reduced flapping lift) turning this configuration into an efficient sea skimming airframe). Add the lag in stealth design, the easiest way of reverse engineering* something that is not top notch in term of aero technology and you've got the J-20.

*reverse engineering has (nearly) nothing to do with spying and paying bribes to corrupt foreign assets
So, if that's your explanation for the J-20's configuration, what do you think about Song Wencong's paper? A bunch of hot air? ::)
Just remember Blitzo, China has never been able to build from scratch their own set of wings, but they’re also so good at copying and reverse engineering that they build from scratch reverse engineered Flanker wings all the time. Those J-10 wings? Not scratch built. They needed help from some unspecified foreign country to build those!
 

latenlazy

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Blitzo said:
latenlazy said:
TomcatViP said:
LERX are draggy. Canards are Draggy. Delta are draggy. You don't add a to b and c just for the fun of it. It's a constraint based equation. If they had at the time active fluidic ctrl knowledge for example and blablabla, the J-20 would have been something different. I am sure that the next iteration of Chinese fighter will sport a different configuration. But obviously we would have to wait and see.
You forgot to mention tails. Tails are draggy. Oh and also wings that aren’t deltas. Those kinds of wings are draggy too! By your logic there’s no such thing as a maneuverable fighter because no fighter uses active fluidic controls.

Your a+b+c logic also does not hold. Let’s just discard every other factor for drag and just focus on feature count shall we? A small canard adds just as much drag as a large tail. A large aspect ratio LERX adds just as much drag as small one! Never mind other geometries on the plane. The only things that count as draggy are canards, LERXes, and Deltas! This is a nonsensical argument. Drag is determined by the net interaction between the airflow and the whole shape in question, not a few cherry picked parts, treated as categorical variables with all other geometric considerations discarded.
honestly, I laughed at the idea of a J-20 without delta wing, without canards, without LERX.
It'll literally be the central fuselage with tails. It certainly won't be very draggy! ;D

10/10
A fighter that is made of pure air would be the most ideal. No drag whatsoever! (okay maybe laminar drag if we’re going to be spoilers here).
 

latenlazy

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TomcatViP said:
Baaah. Aerodynamics and national pride: an old story...
Would be a more effective retort if you were actually demonstrating a comprehension for aerodynamic basics...but I suppose when fake technical expertise is being called out “national pride” is an easy scapegoat in these discussions. That’s the real old story here.
 

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latenlazy said:
TomcatViP said:
Baaah. Aerodynamics and national pride: an old story...
Would be a more effective retort if you were actually demonstrating a comprehension for aerodynamic basics...but I suppose when fake technical expertise is being called out “national pride” is an easy scapegoat in these discussions. That’s the real old story here.
Nah, he's right though, J-20 would have way less drag if they got rid of the canards, LERX and delta wings. Let's give credit where it's due here. Sometimes we should recognize genius for what it is.
 

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Secret Forum rules 7.5

Personal attacks on others are always inappropriate. Disagree all you like with their ideas or opinions, but don't resort to name-calling or flaming. Argue facts, not personalities.
In case you are lost, have a look here: https://www.secretprojects.co.uk/forum/index.php/topic,21728.0.html
 

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PaulMM (Overscan) said:
The article describes a very specific aerodynamic configuration where the LERX and canard work together to increase maximum lift higher than either in isolation, and higher than the F-22 configuration.

it also reduces wing sweep to a moderate value which improves lower speed performance as well as moving the wing backward, allowing more room for a centrally located weapons bay.

It also describes all-moving vertical tails, angled out, and even shows a rough drawing of the rear fuselage showing the extended tail fairings. Its not a generic canard delta configuration by any means. This is a fix to some aerodynamic downsides of the J-10 configuration and an attempt to create a configuration that outmaneuvers the F-22/Eurocanards.

The fact it retained the canard implies that maneuverability remained of prime importance after 2001. Its an air superiority aircraft with secondary interceptor/strike roles.
Bingo.

Of course, with underpowered engines currently it won't be able to meet its full potential, and when the aircraft is only being introduced in low numbers at first it will naturally be used in the most efficient way possible (anti force multiplier/tanker/AEW&C, possibly acting as battle manager for 4th gen fighters etc), but going into next decade once it receives WS-15 and the production run continues, it take on the primary air superiority and secondary multirole mantle it was designed for.
 

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TomcatViP said:
Secret Forum rules 7.5

Personal attacks on others are always inappropriate. Disagree all you like with their ideas or opinions, but don't resort to name-calling or flaming. Argue facts, not personalities.
In case you are lost, have a look here: https://www.secretprojects.co.uk/forum/index.php/topic,21728.0.html
Who accused others of making arguments based on national pride again? Is calling my points national pride arguing facts or personality? Maybe I’m not the one lost here.
 

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TomcatViP said:
LERX are draggy. Canards are Draggy. Delta are draggy. You don't add bigg a to large b and small c just for the fun of it. It's a constraint based equation*. If they had at the time better knowledge for example and blablabla, the J-20 would have been something different. I am sure that the next iteration of Chinese fighter will sport a different configuration. But obviously we would have to wait and see.

*and it's difficult to sum it up in two lines!
(Is it safe to conclude) that based on China's level of tech development around 2005 that the J-20's layout is mostly a riskier Carnard/Lerx/Lifting body
due to lack of being able to "borrow" or reverse engineer the wings, engine, and fuselage of an F-22?

Would the F-22 have been what China really wanted had they the tech at the time?

Would the F-22 have superior supersonic performance based on the J-20s compromises?
 

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kcran567 said:
(Is it safe to conclude) that based on China's level of tech development around 2005 that the J-20's layout is mostly a riskier Carnard/Lerx/Lifting body
due to lack of being able to "borrow" or reverse engineer the wings, engine, and fuselage of an F-22?

Would the F-22 have been what China really wanted had they the tech at the time?

Would the F-22 have superior supersonic performance based on the J-20s compromises?
That's a good question and it was discussed at length for quite a while even back from the J-XX days.

Over the years I think the consensus was that they knew their engines were the bottleneck, so to achieve more competitive aerodynamic performance with initially underpowered engines they needed to adopt the more unconventional configuration. For J-XX SAC offered what was essentially an F-22 with canards, yet PLAAF rejected it in favour of CAC's canard delta.

I suspect if their engine tech were able to keep up to pace with other technological domains for J-20, that it might've ended up with a more F-22 configuration, because they would've been able to achieve more competitive performance using a more conventional configuration.


The question is how will J-20's more unconventional configuration end up interacting with engines suited to J-20's weight compared to the F-22's more conventional configuration... (Edit: of course a direct comparison wouldn't be proper considering the difference in internal volume, i.e.: J-20's seemingly greater emphasis on internal fuel aka endurance/range, not to mention other unknown factors like materials composition leading to differences in empty weight and so on... but it's interesting to speculate)
 

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Blitzo said:
kcran567 said:
(Is it safe to conclude) that based on China's level of tech development around 2005 that the J-20's layout is mostly a riskier Carnard/Lerx/Lifting body
due to lack of being able to "borrow" or reverse engineer the wings, engine, and fuselage of an F-22?

Would the F-22 have been what China really wanted had they the tech at the time?

Would the F-22 have superior supersonic performance based on the J-20s compromises?
That's a good question and it was discussed at length for quite a while even back from the J-XX days.

Over the years I think the consensus was that they knew their engines were the bottleneck, so to achieve more competitive aerodynamic performance with initially underpowered engines they needed to adopt the more unconventional configuration. For J-XX SAC offered what was essentially an F-22 with canards, yet PLAAF rejected it in favour of CAC's canard delta.

I suspect if their engine tech were able to keep up to pace with other technological domains for J-20, that it might've ended up with a more F-22 configuration, because they would've been able to achieve more competitive performance using a more conventional configuration.


The question is how will J-20's more unconventional configuration end up interacting with engines suited to J-20's weight compared to the F-22's more conventional configuration... (Edit: of course a direct comparison wouldn't be proper considering the difference in internal volume, i.e.: J-20's seemingly greater emphasis on internal fuel aka endurance/range, not to mention other unknown factors like materials composition leading to differences in empty weight and so on... but it's interesting to speculate)
I’m actually not as sure they would have arrived at an F-22 like configuration without the engine bottleneck. I get the feeling that even without the engine bottleneck CAC would have probably gone with a delta canard of some sort anyways. They may have struck a different set of compromises though, but it probably would have the same planform, as it was the one they had the most familiarity with. Meanwhile, if what we’ve heard about the J-XX’s history is correct then its unlikely CAC wouldn’t have gotten the tender, given how much more proactively inventive they supposedly were than SAC in their approach to the contest.

To be clear to the original question I don’t think an inability to copy the F-22’s physical features had anything to do with the approach they ended up choosing for the J-XX. Nothing in their capabilities prohibited them from going with a design like the J-31 for example. An F-22 like design wasn’t pursued because it probably didn’t fit their set of requirements and conditions.
 

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latenlazy said:
I’m actually not as sure they would have arrived at an F-22 like configuration without the engine bottleneck. I get the feeling that even without the engine bottleneck CAC would have probably gone with a delta canard of some sort anyways. They may have struck a different set of compromises though, but it probably would have the same planform, as it was the one they had the most familiarity with. Meanwhile, if what we’ve heard about the J-XX’s history is correct then its unlikely CAC wouldn’t have gotten the tender, given how much more proactively inventive they supposedly were than SAC in their approach to the contest.

To be clear to the original question I don’t think an inability to copy the F-22’s physical features had anything to do with the approach they ended up choosing for the J-XX. Nothing in their capabilities prohibited them from going with a design like the J-31 for example. An F-22 like design wasn’t pursued because it probably didn’t fit their set of requirements and conditions.
Very true, ultimately we don't know how much more ambitious or experimental the PLAAF may have been if their engine technology at the time was up to par with the other important domains, merely only talking about aerodynamics.

Range/endurance is of course the other big requirement that directly affects the aerodynamics and kinematics of the aircraft. J-20 certainly does have more fuselage volume than F-22 (though of course it isn't 23m long ::) ) and I suspect that was probably a consequence of greater range/endurance requirement than the USAF gave for F-22 at the time.

I wonder what J-20 would've looked like if PLAAF's range/endurance requirement happened to be more similar to that of the F-22, but retaining the same kind of aerodynamic demands and constrained by the same kind of engine limitations.
 

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Blitzo said:
I wonder what J-20 would've looked like if PLAAF's range/endurance requirement happened to be more similar to that of the F-22, but retaining the same kind of aerodynamic demands and constrained by the same kind of engine limitations.
A smaller fighter more specialized for point defense like what they ended up doing with the J-10, I’d imagined, since those constraints are very similar.
 

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https://www.flightglobal.com/news/articles/j-20s-in-conservative-flying-display-over-zhuhai-453351/

The show started with a three aircraft flyby, after which two aircraft performed a series of sweeping turns in tight formation. A solo aircraft also performed a series of rolls and a sharp climb before climbing out of the show and departing.

While the performance highlighted the type’s large size, there was a lack of aggressive maneuvers, such as the falling leaf and tight vertical loops. At air shows, such maneuvers are routine for the types to which the J-20 is most often compared, the Lockheed Martin F-22, and the Sukhoi Su-35.

06 NOVEMBER, 2018 SOURCE: FLIGHTGLOBAL.COM BY: GREG WALDRON ZHUHAI
The Chengdu J-20 appeared in this year’s flying display at Airshow China, performing a conservative flying routine.

The show started with a three aircraft flyby, after which two aircraft performed a series of sweeping turns in tight formation. A solo aircraft also performed a series of rolls and a sharp climb before climbing out of the show and departing.

While the performance highlighted the type’s large size, there was a lack of aggressive maneuvers, such as the falling leaf and tight vertical loops. At air shows, such maneuvers are routine for the types to which the J-20 is most often compared, the Lockheed Martin F-22, and the Sukhoi Su-35.

Still, the J-20 performance was a few minutes longer than at the 2016 show, where two aircraft made a pass over the crowd. One aircraft then departed, leaving its partner to conduct a few turns before climbing out of the show.

For the first time, AVIC distributed a flyer with a very brief description of the aircraft: “The J-20 developed independently by China is a heavy stealth fourth-generation fighter (aka fifth generation internationally), renowned for its dominant role of medium & long range air combat and excellent capability in ground & marine precision strike,” it states.

“Its overall combat effectiveness marks significant improvement compared with that of third-generation fighters. Major operational missions include: seizing and maintaining air superiority, medium & long-range fast interception, escort and deep strike.”
Unless AVIC is purposefully trying to fool people I think we've got the definitive answer for the J-20's intended purpose(s).
 

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siegecrossbow said:
https://www.flightglobal.com/news/articles/j-20s-in-conservative-flying-display-over-zhuhai-453351/

The show started with a three aircraft flyby, after which two aircraft performed a series of sweeping turns in tight formation. A solo aircraft also performed a series of rolls and a sharp climb before climbing out of the show and departing.

While the performance highlighted the type’s large size, there was a lack of aggressive maneuvers, such as the falling leaf and tight vertical loops. At air shows, such maneuvers are routine for the types to which the J-20 is most often compared, the Lockheed Martin F-22, and the Sukhoi Su-35.

06 NOVEMBER, 2018 SOURCE: FLIGHTGLOBAL.COM BY: GREG WALDRON ZHUHAI
The Chengdu J-20 appeared in this year’s flying display at Airshow China, performing a conservative flying routine.

The show started with a three aircraft flyby, after which two aircraft performed a series of sweeping turns in tight formation. A solo aircraft also performed a series of rolls and a sharp climb before climbing out of the show and departing.

While the performance highlighted the type’s large size, there was a lack of aggressive maneuvers, such as the falling leaf and tight vertical loops. At air shows, such maneuvers are routine for the types to which the J-20 is most often compared, the Lockheed Martin F-22, and the Sukhoi Su-35.

Still, the J-20 performance was a few minutes longer than at the 2016 show, where two aircraft made a pass over the crowd. One aircraft then departed, leaving its partner to conduct a few turns before climbing out of the show.

For the first time, AVIC distributed a flyer with a very brief description of the aircraft: “The J-20 developed independently by China is a heavy stealth fourth-generation fighter (aka fifth generation internationally), renowned for its dominant role of medium & long range air combat and excellent capability in ground & marine precision strike,” it states.

“Its overall combat effectiveness marks significant improvement compared with that of third-generation fighters. Major operational missions include: seizing and maintaining air superiority, medium & long-range fast interception, escort and deep strike.”
Unless AVIC is purposefully trying to fool people I think we've got the definitive answer for the J-20's intended purpose(s).
Wonder if they’ll throw in “dominant close range” as well once they give it TVC.
 

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Lack of close range *may* serve as another small indication of the possibility that j20 does not have a gun installed.

Anyway, that description is pretty much what I would expect anyway. With the exception of maritime strike mention. That's a quite weird mission for a premier plaaf (not planaf) fighter that won't be around in high numbers for at least a decade. While I guess a planaf variant is possible, why would they talk about such a far off variant now? Which leads me to conclude that the flyer text may be equally propaganda as it is accurate representation of its role.
 

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I suspect that they're talking about various missions that the J-20 as it is will be intended to fulfill as additional blocks and integration happen. For example I'd be surprised if J-20 was already integrated with various A2G PGMs. Naval strike will be even further down the line with a small diameter AShM most likely.
 

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totoro said:
Lack of close range *may* serve as another small indication of the possibility that j20 does not have a gun installed.
Lol. I actually had the exact same thought.
 

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http://www.xinhuanet.com//mil/2018-11/08/c_129988418.htm via https://lt.cjdby.net/thread-2509274-1-2.html

Xinhua News Agency, Guangzhou, November 7th: Interview with 歼-20 first flight test pilot Li Gang: Secret story behind the 歼-20 test flight Xinhua News Agency reporters Li Xueyong, Huang Ming, Huang Shubo

at the 12th Zhuhai Air Show, Painting, new formations, new attitudes, the stunning appearance of the 歼-20 three-machine formation is undoubtedly the biggest "egg" brought to the audience by this year's air show.

歼-20 From the previous air show two-machine formation more than 1 minute of "stunning a glimpse", to the current three-aircraft formation ignited the audience climax, always let the public full of expectations. On the 7th, Li Gang, the winner of the Air Force's "Golden Medal of the Meritorious Flying Personnel Medal of Honor", accepted an interview with Xinhua News Agency on the 7th and elaborated on the wonderful story behind the 歼-20 test flight.

歼-20 First flight success time: just made up eight "one"

On January 11, 2011, the Chinese 歼-20 stealth fighter successfully made its first flight in Chengdu. As a new generation of stealth fighters in China, the J-20 opened the "20" era of the Chinese Air Force and also announced the arrival of the "Invisible Era."

Recalling the moment seven years ago, Li Gang is still difficult to hide. "As a test pilot, I was lucky to be the first to fly the 歼-20 verification machine."

At 1:11 pm on January 11, 2011, Li Gang took the flight and took off. "Time is just eight 'one'!" Li Gang said that time is purely coincidental. The first flight plan scheduled for the 7th was postponed to 11th due to weather conditions in Chengdu.

At 13:11 on the same day, Li Gang took the flight and took off. For this historical moment, Li Gang, a soldier, is more willing to understand it as 1:11 pm, just to make up eight "ones" - "I feel proud." Li Gang said.

China's most fantastic fighter: "Information is in front of you, control on the fingertips"

was asked about the driving experience of the 歼-20, Li Gang used two words with unlimited imagination to describe: "Dream!"

The cockpit of the 歼-20 is not only spacious and simple, but also has a reasonable layout and a very comfortable driving experience. It is called “the most dreamy fighter” by China.

"All those who have seen the 歼-20 cockpit will sigh: so neat, there are so few electric switches!" Li Gang said that in the cockpit of the 歼-20, both soft and hard switches are very modern.

Li Gang said that the cockpit of the 歼-20, no matter what the electric door, knows what it is for according to the switch; when you fly at night, you know what the electric door is, and it has a good error-proof design. “Operation is like playing games on a mobile phone, from launching a target to launching a missile very fast.”

A pilot once described the experience of driving a 歼-20, an integrated LCD display, a simple electric door switch... "Information is in front of you, control is on the fingertips."

"Maybe many sci-fi things in reality are becoming reality through technology." Li Gang said.

Cockpit layout:

Li Gang, the pilot's cockpit “painted” on the drawings, said that the cockpit layout is very important for an airplane. The cockpit design of the 歼-20 was called “the best office” by Li Gang. The success of the cockpit was due to the in-depth participation of the 试-20 chief designer and the Chinese Academy of Sciences academician Yang Wei.

“Yang Wei sent us a lot of blank cockpit maps, gave a lot of small pictures of the switch, let us experience it, and put the corresponding switch on the position that we think is reasonable.” Li Gang said, if everyone posted In one position, the explanations are consistent; if they are inconsistent, they will meet for discussion.

In Li Gang’s impression, such discussions have gone through at least five rounds. “Finally, all the cockpit layouts are a result of coordination.”

From the drawings drawn by the test flight team, to the wooden cockpit, to the metal cockpit... the designer and the test pilot docked over and over again, to the subtleties Keep improving and become the most sci-fi fighter cockpit in China.

Design concept: Agility is comparable to the 歼-10, the first use of sidebar operation

As China's first stealth fighter, the 歼-20 is inevitably compared with the “one generation machine” 歼-10 in terms of maneuverability.

Li Gang said that due to its stealth demand, the 歼-20 is much more complicated in designing the aerodynamic shape than the general aircraft. After the unremitting efforts of the design team, the 歼-20 has achieved excellent agility and handling, which is no different from the 歼-10.

On the 6th flight demonstration in Zhuhai, the cool body of the 歼-20 three-machine formation pulled up a silver-white vortex in the azure sky, earning the attention and tears of the audience, and the agility is self-evident.

“The 歼-20 cockpit also uses sidebar operation, which is also the first time in the history of Chinese fighters.” Li Gang introduced that this design concept has three advantages: one is that the pilot's vision is clearer; the other is to enhance the agility of the fighter; It is more conducive to the aircraft to carry out large overload flight.

Of course, as China's first stealth fighter, the most attention is still its stealth performance. "Stealth performance is very good!" Li Gang said that as a fighter, stealth performance is critical to combat use.

From the verification machine to the equipment combat troops: thousands of flights were tested.

"It is not easy to equip an aircraft with troops. There are thousands of flights in the middle." Li Gang introduced from the first flight of the 歼-20 verification machine in 2011 to 2014. The first flight prototype, and then officially installed combat troops at the beginning of this year, 歼-20 lasted 7 years to complete the complete process from the first flight to the technical appraisal to the equipment combat troops.

Since 2011, Li Gang has been responsible for the 歼-20 technical model in the Air Force Test Flight Bureau and led the flight test team to complete the 歼-20 test.

"A lot of new technologies of the 歼-20, our country is the first time to adopt." Li Gang said, "In just a few years, I have been so proud of the fact that I have completed such a large number of test flights and equipped the troops so quickly and formed combat capabilities. Glorious."
 

totoro

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The 歼-20 cockpit also uses sidebar operation, which is also the first time in the history of Chinese fighters. Li Gang introduced that this design concept has three advantages: one is that the pilot's vision is clearer; the other is to enhance the agility of the fighter; It is more conducive to the aircraft to carry out large overload flight.
What does the above mean? Sidebar on its own could mean a side stick controller, but the rest of the text makes it clear it's something else. What does "more conducive to the aircraft to carry out large overload flight" even mean?
 

siegecrossbow

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PaulMM (Overscan) said:
http://www.xinhuanet.com//mil/2018-11/08/c_129988418.htm via https://lt.cjdby.net/thread-2509274-1-2.html
Is this Google translate?
 

LowObservable

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An advantage claimed for the sidestick in its early days was that the pilot's arms could be supported at high-g, so I suspect that's what's being talked about.

I don't know why there is so much heat being expended here on the J-20 design. The F-22 influence is obvious, and the missile carriage goals very similar (and that is an enormous design driver) and we also know that the designer had to depend on imported AL-31s, which were not as powerful (particularly dry supersonic) as the F119.

However, the customer and contractor went in a different direction from the F-22 in terms of mission engineering and maneuver requirements. The F-22 is designed with extreme low-speed agility using vectoring but also a high degree of controllability even with vectoring inoperative - hence its gigantic control surfaces. The LO vectoring nozzles are also very heavy. The price is an unexciting fuel fraction.

The PLA and Chengdu apparently realized that a fast airplane for air defense and precision strike needed less emphasis on all-round LO or agility. Result: more available volume with a similar OEW.

It's interesting to look at the overall proportions of an FB-22 "design" exercise from 2002, aimed at trading agility for range. The wing, and no stabilizers, wouldn't have worked for China (tailless and inlay surfaces would have been several bridges too far), so they moved a couple of steps beyond the J-10 and rediscovered all-moving verticals, which for some reason we forgot about in 1965.

In short, J-20 is an object lesson in how to do mission engineering in order to create a configuration that is efficient and not wasteful. It can be argued that an F-22 pilot who gets into a position where he/she needs the TV and the big flappy bits at the back has already messed up.
 

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overscan

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Yep, its Google translate. 'Sidebar controller' is obviously sidestick controller - it improves visibility of the cockpit displays by not blocking valuable real estate near the centre with a control stick, plus its argued to help pilots carry on manouvering under heavy g load as their elbow is supported, not resting on their thigh, as LowObservable says.

As China's first stealth fighter, the J-20 is inevitably compared with the “one generation machine” J-10 in terms of maneuverability.

Li Gang said that due to its stealth demand, the 歼-20 is much more complicated in designing the aerodynamic shape than the general aircraft. After the unremitting efforts of the design team, the 歼-20 has achieved excellent agility and handling, which is no different from the J-10.

On the 6th flight demonstration in Zhuhai, the cool body of the 歼-20 three-machine formation pulled up a silver-white vortex in the azure sky, earning the attention and tears of the audience, and the agility is self-evident.
Of course, as China's first stealth fighter, the most attention is still its stealth performance. "Stealth performance is very good!" Li Gang said that as a fighter, stealth performance is critical to combat use.
Definitely interesting comments here. While thrust-vectoring WS-15 engines would take J-20 to a new level of agility, the initial model is comparable to 'fourth generation' aircraft.

The use of off-the-shelf non-stealthy nozzles on the early J-20 engines suggests they were only ever intended as a temporary solution pending the arrival of a new 'stealthy' nozzle and higher performing engine. Why take the time to planform align all the panel lines surrounding the engine then stick a big RCS beacon in the middle?

The J-10B TVC nozzle shows signs of RCS shaping. Presumably "J-20A" will have the new WS-15 engine and stealthy TVC nozzles similar to the J-10B TVC demonstrator.
 

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PaulMM (Overscan) said:
Presumably "J-20A" will have the new WS-15 engine and stealthy TVC nozzles similar to the J-10B TVC demonstrator.
Wonder if we'd ever see that engine on the T-50/Su-57. That would be quite a twist.
 

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https://www.scmp.com/news/china/military/article/2171987/chinas-new-j-20-stealth-fighter-engine-no-show-zhuhai-air-show
 

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This is a terrible article by a reporter with no credibility in defence reporting. I would ignore it completely.
 

latenlazy

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PaulMM (Overscan) said:
Yep, its Google translate. 'Sidebar controller' is obviously sidestick controller - it improves visibility of the cockpit displays by not blocking valuable real estate near the centre with a control stick, plus its argued to help pilots carry on manouvering under heavy g load as their elbow is supported, not resting on their thigh, as LowObservable says.

As China's first stealth fighter, the J-20 is inevitably compared with the “one generation machine” J-10 in terms of maneuverability.

Li Gang said that due to its stealth demand, the 歼-20 is much more complicated in designing the aerodynamic shape than the general aircraft. After the unremitting efforts of the design team, the 歼-20 has achieved excellent agility and handling, which is no different from the J-10.

On the 6th flight demonstration in Zhuhai, the cool body of the 歼-20 three-machine formation pulled up a silver-white vortex in the azure sky, earning the attention and tears of the audience, and the agility is self-evident.
Of course, as China's first stealth fighter, the most attention is still its stealth performance. "Stealth performance is very good!" Li Gang said that as a fighter, stealth performance is critical to combat use.
Definitely interesting comments here. While thrust-vectoring WS-15 engines would take J-20 to a new level of agility, the initial model is comparable to 'fourth generation' aircraft.
We’ve heard from a pilot before that the J-20 has pretty good subsonic maneuverability and extremely good transonic and supersonic maneuverability. We’ve also heard from another source that’s uncorroborated who said the J-20’s STR is on par with the F-16’s. The comments from the interview you quoted might corroborate the others.
 

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Yep, J-10 subsonic performance is in the same class as F-16. I'd consider this corroborated.
 

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PaulMM (Overscan) said:
The J-10B TVC nozzle shows signs of RCS shaping. Presumably "J-20A" will have the new WS-15 engine and stealthy TVC nozzles similar to the J-10B TVC demonstrator.
J-20A will probably have WS-10 engines that may or may not have TVC nozzles but should have stealthy serrations. I don't think WS-15 will be ready in time for the "A" variant. Then again I'm still not sure what the title of the current in service aircraft are; J-20s or J-20A.


As for talk about J-20's maneuverability, back when J-20 was still J-XX and rumours began to solidify that it would have to use interim engines at first before WS-15, I remember hearing talk about how they would likely try to aim for at least 4th generation performance with interim engines. Of course I don't recall if those were insiders or if it was just a logical deduction, though probably the latter.


In any case, I think achieving 4th generation or J-10 like kinematic performance for J-20 to complement its rf stealth, sensors, weapons, and inherent range/endurance makes it a satisfactory starter stealth fighter capability for the PLA and should allow it to fulfill the air superiority role many times better than the next best 4th generation fighter in the PLA's arsenal.
 

latenlazy

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Blitzo said:
PaulMM (Overscan) said:
The J-10B TVC nozzle shows signs of RCS shaping. Presumably "J-20A" will have the new WS-15 engine and stealthy TVC nozzles similar to the J-10B TVC demonstrator.
J-20A will probably have WS-10 engines that may or may not have TVC nozzles but should have stealthy serrations. I don't think WS-15 will be ready in time for the "A" variant. Then again I'm still not sure what the title of the current in service aircraft are; J-20s or J-20A.


As for talk about J-20's maneuverability, back when J-20 was still J-XX and rumours began to solidify that it would have to use interim engines at first before WS-15, I remember hearing talk about how they would likely try to aim for at least 4th generation performance with interim engines. Of course I don't recall if those were insiders or if it was just a logical deduction, though probably the latter.


In any case, I think achieving 4th generation or J-10 like kinematic performance for J-20 to complement its rf stealth, sensors, weapons, and inherent range/endurance makes it a satisfactory starter stealth fighter capability for the PLA and should allow it to fulfill the air superiority role many times better than the next best 4th generation fighter in the PLA's arsenal.
I think the J-20 more or less turned out as described in Song’s paper. Equivalent subsonic maneuverability and superior transonic and supersonic maneuverability to 4th gen fighters using weaker engines than the 5th gen standard.
 

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latenlazy said:
I think the J-20 more or less turned out as described in Song’s paper. Equivalent subsonic maneuverability and superior transonic and supersonic maneuverability to 4th gen fighters using weaker engines than the 5th gen standard.
it will be very interesting to see how J-20 performs with its intended engines
 

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LowObservable said:
I don't know why there is so much heat being expended here on the J-20 design. The F-22 influence is obvious, and the missile carriage goals very similar (and that is an enormous design driver) and we also know that the designer had to depend on imported AL-31s, which were not as powerful (particularly dry supersonic) as the F119.
Well specifically I think the last page or so was talking about the J-20's specific canard+LERX+delta+all moving tail+lifting body configuration and the aerodynamic performance that was meant to achieve, both in terms of J-20's role and indirectly what kind of performance it's meant to achieve relative to its likely competitors.


And as far as current flying and proposed 5th generation fighters go, I think one has to admit J-20's aerodynamic configuration is among the more unique. Bringing up Song's paper back here naturally would spark some more discussion about the aircraft's aerodynamic configuration
 

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LowObservable said:
The PLA and Chengdu apparently realized that a fast airplane for air defense and precision strike needed less emphasis on all-round LO or agility. Result: more available volume with a similar OEW.
When you create air defence/precision strike l/o airplane, you at least equip it with appropriate deep long bays. Like su-57. Or F-35.
From everything we saw, j-20 bay is a wide and shallow, raptor-like bay of a pure air superiority breed. Which is strongly supported by the presence of smaller WVR bays.
Blitzo said:
And as far as current flying and proposed 5th generation fighters go, I think one has to admit J-20's aerodynamic configuration is among the more unique. Bringing up Song's paper back here naturally would spark some more discussion about the aircraft's aerodynamic configuration
CALF, 1.42
 
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