Chengdu J-20 pictures, analysis and speculation Part II

[Deino]

The LERXes in front of the canards seem to be gone. I kinda miss them. Clearly the adjustments to the J-20's aerodynamics weren't exactly tiny (or those tiny LERXes just didn't matter that much).

Yes, the changes are more significant than I expected at first !

+ the best image so far !!!

 

[sferrin]

What's amazing to me is how fast they're progressing. This almost looks like a production aircraft. It took us 7 years to go from the YF-22 to the F-22A.

 

[Trident]

That is one good-looking plane.

It is! Not ground-breaking like the A-12 and YF-23 were, but it certainly works aesthetically speaking. Most of the differences to the previous demonstrators are for the better in that regard, although I liked the F-22 style canopy better. Still no sign of a gun yet (at least none that I've spotted), which I was half expecting to see when it became clear that there would be major changes.

 

[Deino]

I just put together what's new ... for a report to be publsihed soon.

- a Raptor-style light-grey colour scheme,
- the engines' diverterless supersonic intakes appear to have been re-designed, perhaps to improve the radar cross section characteristics.
- an additional inner canopy frame similar to the F-35
- clipped tails and canards (which now seem to be integrated much better with the forward fuselage)
- re-designed wheel bay doors
- a reduction in the size of the wing actuators
- a new frameless wide-angle holographic head-up display
- an electro optical targeting system protruding under the front fuselage
- several new dielectric panels around the front fuselage
- wider and longer sponsoons/tail stings (where the tails are mounted)
- redesigned LERX with no longer an arc but straight leading edge
- probably a redesigned rear fuselage featuring a wider and deeper “ditch” between both engines.

Did I miss anything ?

 

[pedrospe]

Very impressive new staff,thanks a lot Deino.




regards


pedro

 

[Trident]

I just put together what's new ... for a report to be publsihed soon.

- a Raptor-style light-grey colour scheme,
- the engines' diverterless supersonic intakes appear to have been re-designed, perhaps to improve the radar cross section characteristics.
- an additional inner canopy frame similar to the F-35
- clipped tails and canards (which now seem to be integrated much better with the forward fuselage)
- re-designed wheel bay doors
- a reduction in the size of the wing actuators
- a new frameless wide-angle holographic head-up display
- an electro optical targeting system protruding under the front fuselage
- several new dielectric panels around the front fuselage
- wider and longer sponsoons/tail stings (where the tails are mounted)
- redesigned LERX with no longer an arc but straight leading edge
- probably a redesigned rear fuselage featuring a wider and deeper “ditch” between both engines.

Did I miss anything ?

Nothing of consequence, really:
- square rather than round nose landing gear lights (think Rafale)
- tire fairings for the main landing gear are larger, but it may just be that the re-designed LERX which intersects it is less voluminous than it used to be
- a small ventral bump of unknown function has moved from the port side of the rear fuselage to starboard.

 

[latenlazy]

I just put together what's new ... for a report to be publsihed soon.

- a Raptor-style light-grey colour scheme,
- the engines' diverterless supersonic intakes appear to have been re-designed, perhaps to improve the radar cross section characteristics.
- an additional inner canopy frame similar to the F-35
- clipped tails and canards (which now seem to be integrated much better with the forward fuselage)
- re-designed wheel bay doors
- a reduction in the size of the wing actuators
- a new frameless wide-angle holographic head-up display
- an electro optical targeting system protruding under the front fuselage
- several new dielectric panels around the front fuselage
- wider and longer sponsoons/tail stings (where the tails are mounted)
- redesigned LERX with no longer an arc but straight leading edge
- probably a redesigned rear fuselage featuring a wider and deeper “ditch” between both engines.

Did I miss anything ?

Nothing of consequence, really:
- square rather than round nose landing gear lights (think Rafale)
- tire fairings for the main landing gear are larger, but it may just be that the re-designed LERX which intersects it is less voluminous than it used to be
- a small ventral bump of unknown function has moved from the port side of the rear fuselage to starboard.

Tire farings have actually been lengthened.

 

[Sundog]

It seems that the early prototypes, as was suggested before, were just aerodynamic test beds. It seems that 2011 is the first actual "LO" testbed, given the RAM and the updates. However, I think the intakes were redesigned for aerodynamic, not stealth reasons. High aspect ratio inlets (height vs width), usually aren't as efficient as inlets with a low (1:1 being optimum) aspect ratio. The new inlets are more of a square opening than a rectangular opening in terms of aspect ratio, leading me to believe they were having some efficiency issues with the inlets.

 

[Deino]

By the way I'm still waiting for this image No. 12 !

Deino

 

[latenlazy]

It seems that the early prototypes, as was suggested before, were just aerodynamic test beds. It seems that 2011 is the first actual "LO" testbed, given the RAM and the updates. However, I think the intakes were redesigned for aerodynamic, not stealth reasons. High aspect ratio inlets (height vs width), usually aren't as efficient as inlets with a low (1:1 being optimum) aspect ratio. The new inlets are more of a square opening than a rectangular opening in terms of aspect ratio, leading me to believe they were having some efficiency issues with the inlets.

Also aerodynamic changes to how it generates and manages vortices I think.

 

[Blitzo]

Nothing of consequence, really:
- square rather than round nose landing gear lights (think Rafale)
- tire fairings for the main landing gear are larger, but it may just be that the re-designed LERX which intersects it is less voluminous than it used to be
- a small ventral bump of unknown function has moved from the port side of the rear fuselage to starboard.

I've speculated that the under fuselage bump may be the j-20s EODAS ports, facing forward and back.


Certainly the geometry is near identical to F-35s under fuselage EODAS bump, and on some of the clearer photos you can make out a forward and rear facing window on J-20s bump just like F-35 (though they were probably empty given those were still early prototypes)

 

[overscan (PaulMM)]

Nice angle.

 

[Sundog]

[quote author=PaulMM (Overscan) ]
Nice angle.
[/quote]

Did the earlier variants use their canards as airbrakes on the ground like the Gripen? I don't recall seeing that before.

 

[Radical]

[quote author=PaulMM (Overscan) ]
Nice angle.

Did the earlier variants use their canards as airbrakes on the ground like the Gripen? I don't recall seeing that before.
[/quote]

I'm actually curious about whether they removed the dorsal airbrake or not.

 

[VH]

Compared to the F-22, J-20 still has work to do on the many radar reflecting sharp edges and corners in the rear quarter.

 

[Blitzo]

Compared to the F-22, J-20 still has work to do on the many radar reflecting sharp edges and corners in the rear quarter.

Like what? I think apart from the engine nozzles, everything else is as good as it could be without drastically changing the aircraft's aerodynamics.


Certainly, the tail stings and ventral fins are clearly shaped with RCS reduction in mind.

 

[Blitzo]

[quote author=PaulMM (Overscan) ]
Nice angle.

Did the earlier variants use their canards as airbrakes on the ground like the Gripen? I don't recall seeing that before.

I'm actually curious about whether they removed the dorsal airbrake or not.
[/quote]


I'm curious about actually seeing the dorsal airframe used during landing!

 

[quellish]

Certainly, the tail stings and ventral fins are clearly shaped with RCS reduction in mind.

Why do you say that?

 

[Blitzo]

Certainly, the tail stings and ventral fins are clearly shaped with RCS reduction in mind.

Why do you say that?

Lack of round edges, general absence of 90 degree faces, edge alignment of the fins...
... Are we saying the ventral fins and tail stings aren't designed with stealth shaping in mind?


I could understand if it was claimed that the ventral fins were more detrimental to stealth compared to no ventral fins (though there are other factors to consider), however I think its wrong to say they didn't pay attention to the shaping of the fins and tail stings. Tbh I'm not really sure how much better they could have done it, assuming there were aerodynamic and sensor prerequisites in place that necessitated the presence of these parts.

 

[overscan (PaulMM)]

Nice view. One landing gear blister is truncated and seems to have an an antenna on the front. Wing actuator fairings seem to protrude less and be toed in (angled).

 

[Deino]

also a nice image !

 

[Deino]

There are even more changes ... on the wing, maybe the weapons bay ... ???

 

[overscan (PaulMM)]

There are even more changes ... on the wing, maybe the weapons bay ... ???

Not sure what wing changes you are seeing. Weapons bay - hard to tell. The two images are not exactly the same angle.

 

[Thorvic]

There are even more changes ... on the wing, maybe the weapons bay ... ???

Not sure what wing changes you are seeing. Weapons bay - hard to tell. The two images are not exactly the same angle.

The Lerx is wider from the looks of it

 

[overscan (PaulMM)]

..

 

[Deino]

There are even more changes ... on the wing, maybe the weapons bay ... ???

Not sure what wing changes you are seeing. Weapons bay - hard to tell. The two images are not exactly the same angle.

Yes, sadly the images is not exactly the same but IMO the flaps are longer and more narrow on 2011 (going all the way to outboard actuator nacelles). ???

Deino

 

[overscan (PaulMM)]

There are even more changes ... on the wing, maybe the weapons bay ... ???

Not sure what wing changes you are seeing. Weapons bay - hard to tell. The two images are not exactly the same angle.

Yes, sadly the images is not exactly the same but IMO the flaps are longer and more narrow on 2011 (going all the way to outboard actuator nacelles). ???

Deino

Yes, the flaps might be a little different - this would tie in with the changed actuators. I thought you meant more structural changes.

 

[JFC Fuller]

Lost of interesting hexagon shaped panels on the forward fuselage, both behind the air intakes and on the nose where there is also a nice pentagon shaped black panel.

 

[quellish]

Lost of interesting hexagon shaped panels on the forward fuselage, both behind the air intakes and on the nose where there is also a nice pentagon shaped black panel.

Yup. And the angles and edge lengths are not consistent, and many of them have fasteners around them.

 

[Deino]

Yup. And the angles and edge lengths are not consistent, and many of them have fasteners around them.

Care to explain what You want to say with this statement or Your observation ???

To admit I often do not understand these highly technical issues, which are beyond my understanding ! :-[

Anyway they are not the only strange "shapes" around '2011' and some are quite similar to the ES-05 AESA Radar for the Gripen (http://htka.hu/.../upl.../2012/06/Raven_ES-05_AESA_radar.jpg)

In Chinese Forums there are also discussions not only if they are AESA based but also if they could be some kind of directed IFF to better control the emissions and stay stealty ... or if the Chinese would try with antenna repositioner like the Europeans are using on Eurofighter and Gripen? Or if they are for IFF and data link?

Any idea ??

Deino

 

[malipa]

I guess we can conclude that the J-20 is just a great copy of western technology fused together into a 'new' shape. The F-35 nose, with the Gripen's side radar, the F-22 bays, the Eurofighter's canards and the Mikoyan Project 1.44 aft section.

 

[Deino]

Can anyone explain these shapes and structures ???? ???

To admit ... nothing copied from a Western fighter.

 

[overscan (PaulMM)]

Could be a wire mesh cover for something or perforations.


My guess is they are related to the DSI intake like the perforations on the JF-17 intake- with the hexagonal shape intended to reduce RCS implications. I don;t think F-35 needed them. In some respects the JF-17 intake has as much in common with the F-11F-1 as the F-35...

 

[latenlazy]

Could be a wire mesh cover for something or perforations.


My guess is they are related to the DSI intake like the perforations on the JF-17 intake- with the hexagonal shape intended to reduce RCS implications. I don;t think F-35 needed them. In some respects the JF-17 intake has as much in common with the F-11F-1 as the F-35...

2001 and 2002 didn't seem to need them either, and far as I can tell, neither did the J-10B. It's also a little strange to put the perforations far behind the bump in an area that doesn't seem to have anything to do with the boundary layer going into the inlet. It's probably too far forward of the engines to be a bleed for the inlet tunnel though?

 

[Grey Havoc]

Can anyone explain these shapes and structures ???? ???

To admit ... nothing copied from a Western fighter.

Conformal antennas for part of the Electronic Warfare system would be my first guess.

 

[overscan (PaulMM)]

They don't look like antennas. Well, perhaps a little bit like an AESA, but no sane designer would expose the elements - it would be behind a frequency selective radome. It could be a screen over an intake or exhaust of some kind.

 

[sferrin]

They don't look like antennas. Well, perhaps a little bit like an AESA, but no sane designer would expose the elements - it would be behind a frequency selective radome. It could be a screen over an intake or exhaust of some kind.

Or it could be what we're seeing is two competing designs of frequency selective radomes. Think F-117 type intake grid over radome material. I'm really curious what that teardrop shaped object is, and why it's shaped the way it is. (Also notice the mat of RAM around it?)

 

[Deino]

I have really no idea about these shapes !

 

[Trident]

I'd say the mesh screens were exit apertures for air from internal boundary layer bleeds, much like the JF-17, as overscan points out. As for the teardrop shaped fairings on the inlets, possibly luneberg lenses to amplify its radar signature? This aircraft appears to be fitted with a full suite of coatings after all, so they might now be required for safe operations in controlled airspace.

 

[sferrin]

I'd say the mesh screens were exit apertures for air from internal boundary layer bleeds, much like the JF-17, as overscan points out. As for the teardrop shaped fairings on the inlets, possibly luneberg lenses to amplify its radar signature? This aircraft appears to be fitted with a full suite of coatings after all, so they might now be required for safe operations in controlled airspace.

But why have a RAM patch around it? ???