Chengdu J-20 news and analysis Part III

[Deino]

Via the SDF:

@latenlazy slow mo high def version if you want to see how the all moving slabs work during the roll.

Sina Visitor System

 

[paralay]

,

 

[latenlazy]

(And also Paralay’s J-20 diagram isn’t even accurate. Do an overlay with one of the many top view photos we now have of the plane if you don’t believe me).

The drawing is really outdated. According to the photo, 25% of the average aerodynamic chord shifted even more backwards, by 160 mm

The J-20 is not a tube with wings.

Via the SDF:

@latenlazy slow mo high def version if you want to see how the all moving slabs work during the roll.

Sina Visitor System

It *just* occurred to me that the video was flipped upside down and now I’m annoyed lol.

 

[TomcatViP]

Yes. The camera moves dramatically aggravate amplitude of the roll and yaw departure.

Anyhow, this is much above the pay grade of a Rafale or Typhoon (at least without any serious aero upgrade). So, Chinese pilots have here a substantial advantage.

 

[Forest Green]

Yes. The camera moves dramatically aggravate amplitude of the roll and yaw departure.

Anyhow, this is much above the pay grade of a Rafale or Typhoon (at least without any serious aero upgrade). So, Chinese pilots have here a substantial advantage.

This is really the least relevant of the advantages against either aircraft though.

 

[sferrin]

Yes. The camera moves dramatically aggravate amplitude of the roll and yaw departure.

Anyhow, this is much above the pay grade of a Rafale or Typhoon (at least without any serious aero upgrade). So, Chinese pilots have here a substantial advantage.

I swear I've seen Typhoon do similar. When I first saw this clip I wondered what the hubub was about. Sure, it's more than we've seen the J-20 do in the past but it was nothing I hadn't seen before. (Still feel the same after having watched the clip a dozen times.)

 

[torginus]

From my understanding, it was far more involved by Kamov than just preliminary design study on Z-10. Y-20 absolutely had Antonov involvement, but not as detailed as Kamov's involment in Z-10. As to J-20, i am mostly joking there. There are some whispers, but they mostly boil down to speculation, there hasnt been concrete evidence or acknowledgment. None the less, i do think there are some parellels between MiG 1.44/1.42 and J-20, both in terms of the design by also the overall philosophy.

For the MiG 1.44, from my understand there are 2 'families' of delta-canard planes.

For close-coupled canards, the vortex systems used by the wings are generated and controlled by the canards. In these kinds of planes, the canards move very little, and there is no leading edge extension for the wings. The 1.44 is such a plane.

For loose-couple canards, the wings have their own vortex generating leading edge extensions. and the canards act as pitch control devices like tails, that are placed in front of the wings. The J-20 is an example of that.

So, additionally considering the position of the intakes, from an aerodynamic perspective, the 2 planes are quite different. That does not prove the absence of taking inspiration or consultation with Russian companies, but the statement that the J-20 is a Chinese MiG does not pass muster.

 

[paralay]

,

 

[F-2]

View: https://m.youtube.com/watch?v=MDbZnaUjy8c
here is one of the better Typhoon demos I’ve seen.

However I have this article from flight global implying the Typhoons knife fighting capability is inferior to the Hornet and Viper without the AMK kit, so it might not be the best.

Eurofighter: new aerodynamics set for 2014 test flight

Eurofighter will by year-end make is final proof-of-concept test flight on an aerodynamic modification kit that promises to improve the combat aircraft's subsonic turn rate by 15%.

www.flightglobal.com

 

[Trident]

I swear I've seen Typhoon do similar. When I first saw this clip I wondered what the hubub was about. Sure, it's more than we've seen the J-20 do in the past but it was nothing I hadn't seen before. (Still feel the same after having watched the clip a dozen times.)

In fact the maneuver resembles what used to be billed as one of Typhoon's signature moves, the High Alpha Velocity Vector Roll (1:25min):

View: https://www.youtube.com/watch?v=mPOOldlZymw

 

[latenlazy]

Yes. The camera moves dramatically aggravate amplitude of the roll and yaw departure.

Anyhow, this is much above the pay grade of a Rafale or Typhoon (at least without any serious aero upgrade). So, Chinese pilots have here a substantial advantage.

I mean, doesn’t really change my conclusion. Just makes visual analysis a little more convoluted (I rewatched the clip with my phone upside down)

Here’s a video that’s not a closeup.

小红书

 

[Dreamfighter]

It surely has some nice tricks up it´s (short, medium or long) sleeve, which doesn´t surprise me.

 

[overscan (PaulMM)]

Certainly shows the "unmanouverable F-111 interceptor / strike" school of thought was pretty far off base.

The J-20 configuration is definitely more optimised for subsonic turns than the Typhoon for example. The LERX are important here. It is also obviously aimed at low supersonic drag for supercruise. It's engine thrust even with interim engines is plenty for subsonic capability - the only potential deficit would be in supercruise.

 

[Dreamfighter]

The J-20 configuration is definitely more optimised for subsonic turns than the Typhoon for example.

Typhoon was/is indeed rather optimized for supersonic turn performance.

 

[F-2]

I have a page from MMRCA claiming the Typhoon has a 16.2 turn rate at 5000 compared to 15 for the Super Hornet. It doesn’t say the conditions but I have an idea from super hornet material that’s about 50-60% internal fuel and a light A2A load. From what I can tell the Typhoon is good but not outstanding in that category, it’s powerful thrust is it’s bread and butter.

 

[overscan (PaulMM)]

Its not sustained turn, but more instantaneous turn capability at low speeds that Typhoon falls behind on compared to F-16 and F-18. Sustained turn is more related to thrust/drag, while instantaneous turn is more related to maximum lift. J-20 configuration is better for instantaneous turns due to the LERX increasing max lift at high AOA. The forward canard can contribute vortex lift, but not at all angles of use.

 

[latenlazy]

Its not sustained turn, but more instantaneous turn capability at low speeds that Typhoon falls behind on compared to F-16 and F-18. Sustained turn is more related to thrust/drag, while instantaneous turn is more related to maximum lift. J-20 configuration is better for instantaneous turns due to the LERX increasing max lift at high AOA. The forward canard can contribute vortex lift, but not at all angles of use.

Your lift coefficient at your bank angle also matters for sustained turn though. So really it’s lift drag coefficient+thrust, or more precisely (angular lift vector+thrust)/drag.

 

[Dreamfighter]

Its not sustained turn, but more instantaneous turn capability at low speeds that Typhoon falls behind on compared to F-16 and F-18.

And better sustained turn capability has more importance for supersonic manoeuvres, while better instantaneous turn performance is usually of more importance for subsonic manoeuvres. F-15 (sustained better) vs Su-27 (instantaneous better) is also such an example.
When Typhoon was designed/developed, the choice was made to add more importance to excel in the supersonic regime.

 

[Sundog]

The point is without knowing the pressure distribution of the flow field you have no way of identifying the relationship between center of gravity and aerodynamic center. The former already sits in a line between the front and back landing gears so that can only be guessed at with rules of thumb and the latter isn’t only unknowable from eyeballing when your plane’s shape is more than just all simple wing geometry or a tube and simple wing geometry, but actually shifts around in different flight envelopes.

As an aeronautical engineer who majored in aerodynamics and minored in propulsion, this is complete nonsense. We have good ideas based on our known calculations regarding how the aircraft will behave in the static domain and to a certain extant in the dynamic domain as well. Where you run into trouble is when the airflow is mainly non-steady, such as at high alpha with massive amounts of flow separation. That's where tools such as CFD, the wind tunnel, and of course, best of all, actual flight testing, come into play.

 

[latenlazy]

The point is without knowing the pressure distribution of the flow field you have no way of identifying the relationship between center of gravity and aerodynamic center. The former already sits in a line between the front and back landing gears so that can only be guessed at with rules of thumb and the latter isn’t only unknowable from eyeballing when your plane’s shape is more than just all simple wing geometry or a tube and simple wing geometry, but actually shifts around in different flight envelopes.

As an aeronautical engineer who majored in aerodynamics and minored in propulsion, this is complete nonsense. We have good ideas based on our known calculations regarding how the aircraft will behave in the static domain and to a certain extant in the dynamic domain as well. Where you run into trouble is when the airflow is mainly non-steady, such as at high alpha with massive amounts of flow separation. That's where tools such as CFD, the wind tunnel, and of course, best of all, actual flight testing, come into play.

"Good ideas" doesn't sound very precise. Either way, my main point is just that claiming to know where the aerodynamic center is accurately enough to say whether a plane is stable or unstable is at best playing very loose with rules of thumb.

 

[red admiral]

The point Either way, my main point is just that claiming to know where the aerodynamic center is accurately enough to say whether a plane is stable or unstable is at best playing very loose with rules of thumb.

Predicting where the CG is from pictures is much harder

 

[siegecrossbow]

Certainly shows the "unmanouverable F-111 interceptor / strike" school of thought was pretty far off base.

The J-20 configuration is definitely more optimised for subsonic turns than the Typhoon for example. The LERX are important here. It is also obviously aimed at low supersonic drag for supercruise. It's engine thrust even with interim engines is plenty for subsonic capability - the only potential deficit would be in supercruise.

In that sense it is a reversal of the Mig-25 situation.

 

[Archibald]

Certainly shows the "unmanouverable F-111 interceptor / strike" school of thought was pretty far off base.

I don't get the point here.

Both F-111B and MiG-25 were as agile as obese elephants, yet their size and weight evenly matches that of a J-20. Big difference since, say, 1964 (year of MiG-25 in March and F-111 in December): digital FBW. Among plenty other tech advances.

So I'm not shocked that a vintage 1964 65 000 pounds "fast missile truck" has little or none agility - when a 2022 65 000 pounds "fast missile truck", is doing better in that regard.

In fewer words: maybe the "big & fast missile truck" idea was all wrong in the 1960's (too expensive and specialized aircraft) but some tech advancements since 50 years have made it much more attractive. Well at least the Chinese seems to have pulled it out in a way they can afford.

 

[TomcatViP]

Don't forget that we have no idea:
- what the takeoff weight was
- if any pilots skills are involved

Much of us can fly most of the things included in our licenses category. Not much of us can fly like Bob Hoover

(I have already voiced how it is possible that J-20 is a quite challenging fighter to fly. So I won't expand on this here.)

 

[siegecrossbow]

Don't forget that we have no idea:
- what the takeoff weight was
- if any pilots skills is involved

Much of us can fly most of the things included in our licenses category. Not much of us can fly like Bob Hoover

(I have already voiced how it is possible that J-20 is a quite challenging fighter to fly. So I won't expand on this here.)

To the best of my knowledge thwse planes didn’t takeoff/land at the Changchun airport and the closest military bases are a couple hundred miles away. I don’t think they pulled off any dirty tricks, or at least not to the extent that Grumman did for the Shah of Iran.

 

[sferrin]

 

[helmutkohl]

^ while the J-20 is an impressive plane

NGL.. I personally don't like the visual aesthetics of this trend towards metallic looking coating/layers. reminds me of 50s era aircraft.
but I understand it has a lot of functionality in reducing radar signature.

 

[Blitzo]

Certainly shows the "unmanouverable F-111 interceptor / strike" school of thought was pretty far off base.

I don't get the point here.

Both F-111B and MiG-25 were as agile as obese elephants, yet their size and weight evenly matches that of a J-20. Big difference since, say, 1964 (year of MiG-25 in March and F-111 in December): digital FBW. Among plenty other tech advances.

So I'm not shocked that a vintage 1964 65 000 pounds "fast missile truck" has little or none agility - when a 2022 65 000 pounds "fast missile truck", is doing better in that regard.

In fewer words: maybe the "big & fast missile truck" idea was all wrong in the 1960's (too expensive and specialized aircraft) but some tech advancements since 50 years have made it much more attractive. Well at least the Chinese seems to have pulled it out in a way they can afford.

The fact that J-20 is a relatively large aircraft is not a matter of debate.

However the idea that J-20 was a dedicated un-maneouverable interceptor or strike aircraft was largely a result of people:
A) assuming it was a bit larger than it really was (some people initially thought it was 23m long!, and thus the comparisons to F-111 emerged), and
B) eyeballing the aerodynamic design of the aircraft in early years and assuming (for some reason) that it wasn't designed for competent kinematic maneuvering

 

[aonestudio]

https://twitter.com/x/status/1565995515048873985

View: https://twitter.com/HenriKenhmann/status/1565995515048873985

 

[Hank58]

Beautiful photo of the chin-mounted optics blister on the J-20 with the windows exposed.
Seems like most photos show it either covered (environmental protection, limit abrasion), or with a windowless dummy blister installed.

 

[Hank58]

...although I'm puzzled by the panel fasteners. You would think that those would at least be filled with "butter" to limit their signature contribution. Wonder if this is a check-flight after some maintenance, but before any signature tune-up?

 

[Deino]

...although I'm puzzled by the panel fasteners. You would think that those would at least be filled with "butter" to limit their signature contribution. Wonder if this is a check-flight after some maintenance, but before any signature tune-up?

It’s an image taken at the latest airshow.

 

[Hank58]

...airshow! Doubly interesting. Was that a message; showing the optics windows?

 

[sferrin]

...although I'm puzzled by the panel fasteners. You would think that those would at least be filled with "butter" to limit their signature contribution. Wonder if this is a check-flight after some maintenance, but before any signature tune-up?

It’s an image taken at the latest airshow.

Any video available of the performance?

 

[Deino]

...although I'm puzzled by the panel fasteners. You would think that those would at least be filled with "butter" to limit their signature contribution. Wonder if this is a check-flight after some maintenance, but before any signature tune-up?

It’s an image taken at the latest airshow.

Any video available of the performance?

Posted already a few posts above

 

[sferrin]

...although I'm puzzled by the panel fasteners. You would think that those would at least be filled with "butter" to limit their signature contribution. Wonder if this is a check-flight after some maintenance, but before any signature tune-up?

It’s an image taken at the latest airshow.

Any video available of the performance?

Posted already a few posts above

This one:

https://www.secretprojects.co.uk/threads/chengdu-j-20-news-and-analysis-part-iii.28479/page-28#post-549590

For whatever reason that link just spins and spins and nothing happens.

 

[sienar]

Try this one; https://weibo.com/5119844827/M3dr2tLki

 

[sferrin]

No dice. Tried with and without VPN, changing VPN to other countries, same thing. Oh well.

 

[stealthflanker]

No dice. Tried with and without VPN, changing VPN to other countries, same thing. Oh well.

I got your back

 

[sferrin]

No dice. Tried with and without VPN, changing VPN to other countries, same thing. Oh well.

I got your back

I've seen that one. I was hoping somebody had the entire performance.