Chengdu J-20 news and analysis Part III

[Sferrin]

https://twitter.com/x/status/1593213742015459329

View: https://twitter.com/sugar_wsnbn/status/1593213742015459329

 

[Deino]

Finally officially confirmed!!

A J-20 fitted with WS-15 has already taken its maiden flight. Apparently the speaker in that video is a famous academician from the Chinese Academy of Engineering. He is allegedly specialized in turbofan engines.

Video by @星辰大海SLC on Bilibili.

https://twitter.com/x/status/1602687065749131271

View: https://twitter.com/Nickatgreat1220/status/1602687065749131271

 

[siegecrossbow]

Finally officially confirmed!!

A J-20 fitted with WS-15 has already taken its maiden flight. Apparently the speaker in that video is a famous academician from the Chinese Academy of Engineering. He is allegedly specialized in turbofan engines.

Video by @星辰大海SLC on Bilibili.

https://twitter.com/x/status/1602687065749131271

View: https://twitter.com/Nickatgreat1220/status/1602687065749131271

What’s funny is that the news leaked in late November but no one even talked about it.

 

[Sferrin]

What are the specs supposed to be?

 

[icyplanetnhc (Steve)]

It appears to state that the thrust-to-weight ratio of Chinese 3rd generation (analogous 4th generation by Western definition) turbofans is 8, while for the 4th generation (analogous to 5th generation by Western definition) is 10, and for the next generation is 15.

 

[Geo]

Finally officially confirmed!!

A J-20 fitted with WS-15 has already taken its maiden flight. Apparently the speaker in that video is a famous academician from the Chinese Academy of Engineering. He is allegedly specialized in turbofan engines.

Video by @星辰大海SLC on Bilibili.

https://twitter.com/x/status/1602687065749131271

View: https://twitter.com/Nickatgreat1220/status/1602687065749131271

So the WS-15 is the 4th gen with T/W = 10? Or?

 

[siegecrossbow]

Finally officially confirmed!!

A J-20 fitted with WS-15 has already taken its maiden flight. Apparently the speaker in that video is a famous academician from the Chinese Academy of Engineering. He is allegedly specialized in turbofan engines.

Video by @星辰大海SLC on Bilibili.

https://twitter.com/x/status/1602687065749131271

View: https://twitter.com/Nickatgreat1220/status/1602687065749131271

So the WS-15 is the 4th gen with T/W = 10? Or?

That appears to be the case, yes.

 

[Sevrent]

interesting. This old Chinese paper from 2003 that discusses the development of what led to the J-20. These same numbers show up as well. They describe 4th gen fighters as having engines with a T/W of 8. and Fifth gen fighters as having a T/W of 10. Seems like it's a goal/benchmark by which they differentiate generations?

(Page 4)

https://thediplomat.com/wp-content/uploads/2022/02/thediplomat_2022-02-14-191931.pdf

 

[KUMA]

interesting. This old Chinese paper from 2003 that discusses the development of what led to the J-20. These same numbers show up as well. They describe 4th gen fighters as having engines with a T/W of 8. and Fifth gen fighters as having a T/W of 10. Seems like it's a goal/benchmark by which they differentiate generations?

(Page 4)

https://thediplomat.com/wp-content/uploads/2022/02/thediplomat_2022-02-14-191931.pdf

No, the thrust-weight ratio is only one of the characteristics, not decisive.

The T/W of the engine is linked to the supersonic cruise capability, and it also shows the differences in aviation technology of different generations of fighters, so T/W of engine is regarded as one of the main differences between different generations. However, although it is one of the characteristics, it does not mean that it is the decisive condition.

Just like today, although J-20 using FWS-10 engines with T/W of 8, we still think it is a standard fifth-generation fighter.

 

[Deino]

New prototype no. 2051 spotted with some major changes to the area behind the canopy or canopy itself.

Allegedly the rear section behind the cockpit received some refinements similar to the J-35's different spine to reduce drag and improve transonic performance.

Also, some say this might be the variant powered by the WS-15, even if according to eyewitnesses it still uses WS-10C engines.

 

[helmutkohl]

is it me or does it seem like rear view visability has been reduced as a result.
which seems to be a common trend among 5th gen aircraft bar the f-22

 

[FighterJock]

New prototype no. 2051 spotted with some major changes to the area behind the canopy or canopy itself.

Allegedly the rear section behind the cockpit received some refinements similar to the J-35's different spine to reduce drag and improve transonic performance.

Also, some say this might be the variant powered by the WS-15, even if according to eyewitnesses it still uses WS-10C engines.

View attachment 689980View attachment 689981

First J-20 with WS-15 engines if true? That will boost the performance by quite a lot I would imagine Deino, I would also tend to think that any further J-20s fitted out with the WS-15 will be able to supercruise as well something that they were lacking on previous models.

 

[Deino]

Here's already a first side profile available for comparison: On top prototype no. 2051 aka eventually J-20B and on the bottom the regular J-20A.

 

[Josh_TN]

New prototype no. 2051 spotted with some major changes to the area behind the canopy or canopy itself.

Allegedly the rear section behind the cockpit received some refinements similar to the J-35's different spine to reduce drag and improve transonic performance.

Also, some say this might be the variant powered by the WS-15, even if according to eyewitnesses it still uses WS-10C engines.

View attachment 689980View attachment 689981

First J-20 with WS-15 engines if true? That will boost the performance by quite a lot I would imagine Deino, I would also tend to think that any further J-20s fitted out with the WS-15 will be able to supercruise as well something that they were lacking on previous models.

What engine does the bulk of the existing J20 fleet use? I've seen different versions of the WS-10 and AL-31 mentioned in stuff online but it isn't clear which replaced what when or what the bulk of the production models fly with.

 

[FighterJock]

Here's already a first side profile available for comparison: On top prototype no. 2051 aka eventually J-20B and on the bottom the regular J-20A.
View attachment 689989

Smart images, I notice that the J-20B has a much bigger area behind the cockpit than the regular J-20A, any ideas as to the purpose of the space?

 

[Blitzo]

New prototype no. 2051 spotted with some major changes to the area behind the canopy or canopy itself.

Allegedly the rear section behind the cockpit received some refinements similar to the J-35's different spine to reduce drag and improve transonic performance.

Also, some say this might be the variant powered by the WS-15, even if according to eyewitnesses it still uses WS-10C engines.

View attachment 689980View attachment 689981

First J-20 with WS-15 engines if true? That will boost the performance by quite a lot I would imagine Deino, I would also tend to think that any further J-20s fitted out with the WS-15 will be able to supercruise as well something that they were lacking on previous models.

What engine does the bulk of the existing J20 fleet use? I've seen different versions of the WS-10 and AL-31 mentioned in stuff online but it isn't clear which replaced what when or what the bulk of the production models fly with.

WS-10s

J-20 production fully switched to WS-10 in mid 2019.

 

[F119Doctor]

interesting. This old Chinese paper from 2003 that discusses the development of what led to the J-20. These same numbers show up as well. They describe 4th gen fighters as having engines with a T/W of 8. and Fifth gen fighters as having a T/W of 10. Seems like it's a goal/benchmark by which they differentiate generations?

(Page 4)

https://thediplomat.com/wp-content/uploads/2022/02/thediplomat_2022-02-14-191931.pdf

Focusing on T/W of 10+ is probably the downfall of both the Russian IZD30 and the Chinese WS15. Non AB performance in the supercruise envelope is more important than raw T/W. Big cores for low bypass ratio / supercruise thrust are not lightweight. Trying to push high T/W and supercruise may be well beyond the state of the art, at least for them.

 

[latenlazy]

interesting. This old Chinese paper from 2003 that discusses the development of what led to the J-20. These same numbers show up as well. They describe 4th gen fighters as having engines with a T/W of 8. and Fifth gen fighters as having a T/W of 10. Seems like it's a goal/benchmark by which they differentiate generations?

(Page 4)

https://thediplomat.com/wp-content/uploads/2022/02/thediplomat_2022-02-14-191931.pdf

Focusing on T/W of 10+ is probably the downfall of both the Russian IZD30 and the Chinese WS15. Non AB performance in the supercruise envelope is more important than raw T/W. Big cores for low bypass ratio / supercruise thrust are not lightweight. Trying to push high T/W and supercruise may be well beyond the state of the art, at least for them.

What makes you think that the WS-15 will have poor dry thrust in the supercruise envelope.

 

[Blitzo]

interesting. This old Chinese paper from 2003 that discusses the development of what led to the J-20. These same numbers show up as well. They describe 4th gen fighters as having engines with a T/W of 8. and Fifth gen fighters as having a T/W of 10. Seems like it's a goal/benchmark by which they differentiate generations?

(Page 4)

https://thediplomat.com/wp-content/uploads/2022/02/thediplomat_2022-02-14-191931.pdf

Focusing on T/W of 10+ is probably the downfall of both the Russian IZD30 and the Chinese WS15. Non AB performance in the supercruise envelope is more important than raw T/W. Big cores for low bypass ratio / supercruise thrust are not lightweight. Trying to push high T/W and supercruise may be well beyond the state of the art, at least for them.

T/W ratio just happens to be one of the convenient and simple ways for that paper to describe the next generation engine for 5th generation fighters, I am sure that you've read the paper and that among the other attributes it describes is that the engine is meant to be capable of attaining supercruise without afterburner on an intended aircraft.

I'm not sure how that would lead you to believe that the goal of the engine was to attain a T/W ratio of 10 at the expense of everything else.

 

[F119Doctor]

interesting. This old Chinese paper from 2003 that discusses the development of what led to the J-20. These same numbers show up as well. They describe 4th gen fighters as having engines with a T/W of 8. and Fifth gen fighters as having a T/W of 10. Seems like it's a goal/benchmark by which they differentiate generations?

(Page 4)

https://thediplomat.com/wp-content/uploads/2022/02/thediplomat_2022-02-14-191931.pdf

Focusing on T/W of 10+ is probably the downfall of both the Russian IZD30 and the Chinese WS15. Non AB performance in the supercruise envelope is more important than raw T/W. Big cores for low bypass ratio / supercruise thrust are not lightweight. Trying to push high T/W and supercruise may be well beyond the state of the art, at least for them.

What makes you think that the WS-15 will have poor dry thrust in the supercruise envelope.

I’m not saying that it will have poor supercruise performance with a 0.25 bypass ratio, although there is more to supercruise performance than just low bypass ratio.

I’m saying that the compromises needed to achieve a 10:1+ T/W with supercruise performance are likely to result in a very unreliable short lived engine, taking many more years of development and invention before it is suitable for fleet use.

 

[latenlazy]

interesting. This old Chinese paper from 2003 that discusses the development of what led to the J-20. These same numbers show up as well. They describe 4th gen fighters as having engines with a T/W of 8. and Fifth gen fighters as having a T/W of 10. Seems like it's a goal/benchmark by which they differentiate generations?

(Page 4)

https://thediplomat.com/wp-content/uploads/2022/02/thediplomat_2022-02-14-191931.pdf

Focusing on T/W of 10+ is probably the downfall of both the Russian IZD30 and the Chinese WS15. Non AB performance in the supercruise envelope is more important than raw T/W. Big cores for low bypass ratio / supercruise thrust are not lightweight. Trying to push high T/W and supercruise may be well beyond the state of the art, at least for them.

What makes you think that the WS-15 will have poor dry thrust in the supercruise envelope.

I’m not saying that it will have poor supercruise performance with a 0.25 bypass ratio, although there is more to supercruise performance than just low bypass ratio.

I’m saying that the compromises needed to achieve a 10:1+ T/W with supercruise performance are likely to result in a very unreliable short lived engine, taking many more years of development and invention before it is suitable for fleet use.

We’ve seen 4th gen single crystal turbine blades displayed at air shows as far back as 2018 so I’m not sure you’re quite up to date with the technologies there

 

[F119Doctor]

interesting. This old Chinese paper from 2003 that discusses the development of what led to the J-20. These same numbers show up as well. They describe 4th gen fighters as having engines with a T/W of 8. and Fifth gen fighters as having a T/W of 10. Seems like it's a goal/benchmark by which they differentiate generations?

(Page 4)

https://thediplomat.com/wp-content/uploads/2022/02/thediplomat_2022-02-14-191931.pdf

Focusing on T/W of 10+ is probably the downfall of both the Russian IZD30 and the Chinese WS15. Non AB performance in the supercruise envelope is more important than raw T/W. Big cores for low bypass ratio / supercruise thrust are not lightweight. Trying to push high T/W and supercruise may be well beyond the state of the art, at least for them.

What makes you think that the WS-15 will have poor dry thrust in the supercruise envelope.

I’m not saying that it will have poor supercruise performance with a 0.25 bypass ratio, although there is more to supercruise performance than just low bypass ratio.

I’m saying that the compromises needed to achieve a 10:1+ T/W with supercruise performance are likely to result in a very unreliable short lived engine, taking many more years of development and invention before it is suitable for fleet use.

We’ve seen 4th gen single crystal turbine blades displayed at air shows as far back as 2018 so I’m not sure you’re quite up to date with the technologies there

Pratt & Whitney introduced single crystal turbine airfoils in the early 1980s with the F100-220 engine. Yet supercruise wasn’t a reality until the F119, and I know exactly how much it weighs (I could tell you but the. I would have to kill you )

 

[latenlazy]

interesting. This old Chinese paper from 2003 that discusses the development of what led to the J-20. These same numbers show up as well. They describe 4th gen fighters as having engines with a T/W of 8. and Fifth gen fighters as having a T/W of 10. Seems like it's a goal/benchmark by which they differentiate generations?

(Page 4)

https://thediplomat.com/wp-content/uploads/2022/02/thediplomat_2022-02-14-191931.pdf

Focusing on T/W of 10+ is probably the downfall of both the Russian IZD30 and the Chinese WS15. Non AB performance in the supercruise envelope is more important than raw T/W. Big cores for low bypass ratio / supercruise thrust are not lightweight. Trying to push high T/W and supercruise may be well beyond the state of the art, at least for them.

What makes you think that the WS-15 will have poor dry thrust in the supercruise envelope.

I’m not saying that it will have poor supercruise performance with a 0.25 bypass ratio, although there is more to supercruise performance than just low bypass ratio.

I’m saying that the compromises needed to achieve a 10:1+ T/W with supercruise performance are likely to result in a very unreliable short lived engine, taking many more years of development and invention before it is suitable for fleet use.

We’ve seen 4th gen single crystal turbine blades displayed at air shows as far back as 2018 so I’m not sure you’re quite up to date with the technologies there

Pratt & Whitney introduced single crystal turbine airfoils in the early 1980s with the F100-220 engine. Yet supercruise wasn’t a reality until the F119, and I know exactly how much it weighs (I could tell you but the. I would have to kill you )

4th gen single crystals are not 1st gen single crystals.

 

[icyplanetnhc (Steve)]

It’s not simply a matter of single-crystal airfoils for turbines. An engine designed for supercruise like the F119 has a large core as a result of low bypass ratio and high specific thrust. Even given comparable states of metallurgy technology, such a design isn’t lightweight for its size, and if the Chinese goal is a thrust/weight of 10+, that may be at the cost of the engine’s lifespan.

The F135 achieving a higher thrust/weight ratio is likely because of the larger fan increasing its bypass ratio, while the core size remains about the same as the F119 that it was derived from. It’s also not optimized for supercruise like the F119 is.

 

[Blitzo]

It’s not simply a matter of single-crystal airfoils for turbines. An engine designed for supercruise like the F119 has a large core as a result of low bypass ratio and high specific thrust. Even given comparable states of metallurgy technology, such a design isn’t lightweight for its size, and if the Chinese goal is a thrust/weight of 10+, that may be at the cost of the engine’s lifespan.

The F135 achieving a higher thrust/weight ratio is likely because of the larger fan increasing its bypass ratio, while the core size remains about the same as the F119 that it was derived from. It’s also not optimized for supercruise like the F119 is.

I'm not sure why people are talking about the TWR of the engine as "10+"

It's described in the paper as just 10 (I would know, because I'm the one who bloody translated the thing and wrote the English language pdf for the diplomat and the associated commentary article for it), and while that is technically higher than that of F119 it is also lower than that of F135.


We don't know what the final requirements for WS-15 are in terms of things like TWR, thrust, lifespan etc, but if the argument against the possibility of a WS-15 having a TWR 10, being supercruise capable, without compromising lifespan (relative to if its TWR was say, 9 like that of F119), then that just strikes me as suggesting because F119 and F135 happen to not tick those same boxes in the relative manner that it is inherently technologically more advanced or difficult and thus compromises would be made elsewhere.

And for the record, over the years we've heard TWR goals of 9-10 for WS-15 anyway.

 

[paralay]

,

 

[latenlazy]

It’s not simply a matter of single-crystal airfoils for turbines. An engine designed for supercruise like the F119 has a large core as a result of low bypass ratio and high specific thrust. Even given comparable states of metallurgy technology, such a design isn’t lightweight for its size, and if the Chinese goal is a thrust/weight of 10+, that may be at the cost of the engine’s lifespan.

The F135 achieving a higher thrust/weight ratio is likely because of the larger fan increasing its bypass ratio, while the core size remains about the same as the F119 that it was derived from. It’s also not optimized for supercruise like the F119 is.

I’m well aware that it’s not just about fan blade materials. The main point is that China’s materials for jet engines are much further along than people here seem to believe. What you think is the “comparable state” may actually not be the case.

 

[overscan (PaulMM)]

Yet supercruise wasn’t a reality until the F119

MiG-25 (R15B-300) and MiG-31 (D30F6) look at you with bewilderment

Both require afterburner to cruise supersonically AFAIK.

 

[zjz]

Here's already a first side profile available for comparison: On top prototype no. 2051 aka eventually J-20B and on the bottom the regular J-20A.
View attachment 689989

So it was finally realised that the J-20 is not good at dog fighting, and thus the pilot need not have good backward visibility. And it may have additional advantage of reducing drag with the newer canopy design .....

 

[paralay]

,

 

[overscan (PaulMM)]

Yet supercruise wasn’t a reality until the F119

MiG-25 (R15B-300) and MiG-31 (D30F6) look at you with bewilderment

Both require afterburner to cruise supersonically AFAIK.

Supersonic cruising speed M = 2.3 - 2.35 (2440 km/h - 2500 k/ h), at least 15 minutes of flight, 625 km. Engines in the "minimum afterburner" mode

Minimum afterburner is not no afterburner.

 

[Deino]

Two more photos and - unfortunately I am not allowed to post it yet - No. 2051 already had its first flight.

 

[latenlazy]

Here's already a first side profile available for comparison: On top prototype no. 2051 aka eventually J-20B and on the bottom the regular J-20A.
View attachment 689989

So it was finally realised that the J-20 is not good at dog fighting, and thus the pilot need not have good backward visibility. And it may have additional advantage of reducing drag with the newer canopy design .....

…the J-20 has a 360 distributed sensor system.

 

[Deino]

Here's already a first side profile available for comparison: On top prototype no. 2051 aka eventually J-20B and on the bottom the regular J-20A.
View attachment 689989

So it was finally realised that the J-20 is not good at dog fighting, and thus the pilot need not have good backward visibility. And it may have additional advantage of reducing drag with the newer canopy design .....

Sorry, what a strange conclusion.., but if you want to find a reason for anything you always find one!

 

[David N]

Yet supercruise wasn’t a reality until the F119

MiG-25 (R15B-300) and MiG-31 (D30F6) look at you with bewilderment

As would the English Electric Lightning and Concorde (mach 2.0 with no afterburner), also the Tu-144

 

[F119Doctor]

Yet supercruise wasn’t a reality until the F119

MiG-25 (R15B-300) and MiG-31 (D30F6) look at you with bewilderment

As would the English Electric Lightning and Concorde (mach 2.0 with no afterburner), also the Tu-144

None of which had a T/W of 8+. Which is my point…..

 

[zjz]

…the J-20 has a 360 distributed sensor system.

Nice!

By the way, may I know what is the official reason for the cockpit re-design?

 

[latenlazy]

…the J-20 has a 360 distributed sensor system.

Nice!

By the way, may I know what is the official reason for the cockpit re-design?

We *think* it’s an optimization to simultaneously reduce transonic drag and increase usable internal volume.

 

[zjz]

I saw this reply to @RupprechtDeino on Twitter

https://twitter.com/x/status/1606507887664459776

View: https://twitter.com/palpatine233/status/1606507887664459776


When translated, it means

"Although the frictional resistance is increased, the shock wave resistance is reduced and the space inside the machine is increased"

 

[TomcatViP]

Ah so, better range.