Photos and analysis of China's J-20 fighter as it nears first flight

[Abraham Gubler]

Deino, the exhausts do look different(colour, texture). There are two options here: these are pics of two different aircraft and 2001 and 2002 have been fitted with different engines( the bort number in the top pic is illegible) or 2001 has already had two pairs of engines test-fitted.

You forgot the first option: different light conditions leading to different reflectivity from the uncoated metals of an adjustable nozzle. To assume two engine types from the photos above is hysterical.

 

[flateric]

Well, more sharp eyed guys than me noted that 'J-20 cockpit' is surely a fake and belongs to F-35 mockup - as it was exhibited in 2005 at Bourget
www.youtube.com/watch?gl=US&client=mv-google&hl=en&v=sHJMIOlHt1U
Didn't ever know that Lockheed did some facelifting job since then.

 

[overscan (PaulMM)]

Deino, the exhausts do look different(colour, texture). There are two options here: these are pics of two different aircraft and 2001 and 2002 have been fitted with different engines( the bort number in the top pic is illegible) or 2001 has already had two pairs of engines test-fitted.

You forgot the first option: different light conditions leading to different reflectivity from the uncoated metals of an adjustable nozzle. To assume two engine types from the photos above is hysterical.

I agree wholeheartedly with Abe on this. The nozzles are in different positions - open in one, closed in the other.

2002 is a static test airframe. 2001 is the only flying airframe at present.

 

[Demon Lord Razgriz]

Back before they were revealed I wasn't expecting either 5th gen fighter the Russians or Chinese were supposedly working on to make the F-22A look like a small aircraft.

A friend of mine mentioned that, told him it was likely cause the F-22 was designed purely as an ASF, with the bombs & stuff added very very late in the program, while the J-20 & PAK-FA are more towards multirole/Swing-role.

Would the more acknowledgeable be able to confirm my statement?

 

[rousseau]

I have read your explanation and i like it a day ago i read an article about DSIs however i do not understand something if the bump is fixed, the position of the sonic shock is fixed, on aircraft like the SR-71 the VG inlet moves the shock cone of the inlet to adjust as speed increases, on the MiG-29 inlet for example the shock waves are create ahead of the lower lip so no supersonic flow enters the intake, how can you create a VG DSI inlet if the inlet will make the sonic shock wave inside the intake duct?
On a mirage III the half shock cone of its inlet moves ahead and aft and basicly is similar to the bump of the DSI.

It is the very "bump" block the air stream to be sonic shock inside the inlet. Remember shock-wave present at any surface where slide angle being, but aft shock wave, the air-stream will be low speed flow. The windward of "bump" is where the shock wave is created. This shock wave which shape like a cone corresponding to the "bump" shape cover the lip of inlet, just same present as inlet on Mirage. The shock wave never go inside the inlet, so the adjustable part of VG-DSI merely used to adjust the cross section of duct. The flabellate blade cover the peak of "bump" is possibly make the shock wave go inside the inlet, whereas this is the problem we should think and discuss.
On the other hand, if we are not doctrinaire, changing the DSI to be inner compressure inlet may be the point designer want to do.

I know nozzles will change the diameter of the nozzle from convex to concave depending in the nature of the flow if it is supersonic or subsonic.
but then why raking an inlet? just change the concavity or convexity of the inlet duct and there is no need of shock cone or shock ramps, i do not understand can you elaborate?

Good idea, the key is how? making duct or inlet with uncountably movable blade? B)

 

[Deino]

Deino, the exhausts do look different(colour, texture). There are two options here: these are pics of two different aircraft and 2001 and 2002 have been fitted with different engines( the bort number in the top pic is illegible) or 2001 has already had two pairs of engines test-fitted.

You forgot the first option: different light conditions leading to different reflectivity from the uncoated metals of an adjustable nozzle. To assume two engine types from the photos above is hysterical.

I agree wholeheartedly with Abe on this. The nozzles are in different positions - open in one, closed in the other.

2002 is a static test airframe. 2001 is the only flying airframe at present.

Yep ... and in general I agree with especially since that is the typical behavior from CAC ... but I'm still not 100% sure. I have to admit that I don’t have the aeronautical knowledge or background like many others here … but I think I have a maybe better “feeling” of how the Chinese think …

As such – Sorry - I tend to say its not that simple a question of “open or closed” or the lighting conditions … the AL-31FN's afterburner feathers don’t change colour like that (not seen on a J-10 !)… IMO these are different nozzles, and thus different engines.

The point is: Why do we expect the Chinese to do the things the same way like the US did ?? … I mean only one prototype and then another … ?

Maybe it’s more akin to the ATF-program, when both ATF-prototypes were tested each with different engines … given the amount of recourses (manpower + money) China pushed into its military updates is it that unlikely that we see some kind of “Sino-ATF” ?

Deino

 

[bobbymike]

Underestimating China:

The sudden appearance of a Chinese stealth airplane making high-speed taxi tests in the last couple of weeks was "not a surprise" to US intelligence, Vice Adm. David Dorsett, director of naval intelligence, said Wednesday. Previous Pentagon estimates about China's progress toward stealth aircraft indicated it would be five to 10 years before such a prototype appeared, and Dorsett, speaking with defense reporters in Washington, D.C., did not directly address that disconnect. However, he acknowledged that "we have been pretty consistent in underestimating the delivery and [initial operational capability date] of Chinese technology weapon systems." New Chinese weapons tend to go from prototype to operational service "quicker than we frequently project," said Dorsett, adding that "we need to refine our assessments." He said the taxi tests of the J-20 represent "the front end of a capability that they’re rolling out," and that US intelligence will be "focused on" the aircraft's implications. Despite his admissions about underrating China’s speed of weapons development, he guesstimated that a mature Chinese stealth aircraft integrated with the rest of its military is "years off."

 

[saintkatanalegacy]

I agree with Abe

Lighting conditions from metallic conditions exhibit different results in images

in one picture, light is diffused thus giving a matte impression

in the other picture, light isn't diffused as much resulting to specular light from the metallic surface

another factor is the direction and position of the light source

 

[overscan (PaulMM)]

Put simply, the colour difference is irrelevant due to the effects of lighting, the colour balance of the picture, postprocessing etc. Note on the latest sequence of pics, the nozzle is bright from some angles and dull from others - but the pics are all of one plane. Not to mention individual photos might be deliberately "doctored".

There is also no way at the level of detail currently shown to tell any differences in the exhaust "petals".

Occam's razor applies- there is no evidence of two flying prototypes yet. Jumping to such a conclusion is premature.

 

[Lauge]

....guesstimated that a mature Chinese stealth aircraft integrated with the rest of its military is "years off."

Uhm.....just like when they guesstimated that "....it would be five to 10 years before such a prototype appeared...." :

Cue "military intelligence" joke.

Regards & all,

Thomas L. Nielsen
Luxembourg

 

[saintkatanalegacy]

hmmm... false coloring reveals that they have the same band in the middle of the nozzle B)

 

[rousseau]

They got F101 but are not comprehended so have to back to AL-31, could you image they developed their owe engine such quickly?

 

[saintkatanalegacy]

engine, unlike most other parts, takes a long while to develop...

 

[QuadroFX]

Rumoured Cockpit 2 for 2002 【2002 is Backopening】， not for f35

Heh...

 

[Deino]

hmmm... false coloring reveals that they have the same band in the middle of the nozzle B)

Really ?? ??? ... all I see are two different coloured nozzles. If these are because of the mentioned reasons or because of different engines ... ???

Deino

 

[Deino]

Anyway ... here are more videos...

Frontal view of the aircraft.
http://www.youtube.com/watch?v=R2CjjY7AJio&feature=player_embedded

Actuation of the canards.
http://www.youtube.com/watch?v=VsqepeDzJpQ&feature=player_embedded

J-20 Taxiing.
http://www.youtube.com/watch?v=3BzHjdIGqrA&feature=player_embedded

Cheers, Deino

 

[saintkatanalegacy]

one thing I've also noticed is that they are both at full diameter based on the false color image

low contrasting give you the impression that the other image has a smaller diameter but upon examination, they're actually the same size

regarding the color of the nozzle in the left image, it's not easily noticeable due to high specular lights

but, if you apply false coloring, you will notice that the starboard nozzle actually has a "gradient" instead of a line; this of course is the result of different lighting conditions which creates the illusion that they are totally different nozzles

 

[sferrin]

They got F101 but are not comprehended so have to back to AL-31, could you image they developed their owe engine such quickly?

??? ???

 

[saintkatanalegacy]

ah-ha!

those aren't bands! those are actually shadows from the fins!(referring to the previous pictures of course)

 

[Deino]

ah-ha!
those aren't bands! those are actually shadows from the fins!(referring to the previous pictures of course)

??? Sadly on my composed picture all engines on the Flankers are closed ...

 

[Deino]

Seems as if the first flight is set for tomorrow ... if the weather is ok.

 

[Deino]

;D

 

[PAK FA]

;D

it looks a really cool aircraft, however i can not distinguish well it it has planforming alignment. the canard leading edge and wing leading edge look not aligned and the trailing edges might be aligned well but still it looks cool

 

[Mike Pryce]

The views from above show that the entire main wing is behind the C. of G. (which has to be ahead of the mainwheels).

I think that, even with lots of canard/forebody lift, that would still make it a less than ideal dogfighter. I think this is a big, twin engine, stealthy SAAB Viggen. Strike/secondary interception, with a wide C. of G. range for carrying/trimming diverse, heavy stores.

This is unlike, say, the Typhoon, which has a close coupled canard and a relatively further forward, and hence more unstable/manouverable, wing layout.

Will be interesting to see how the canard trims it - if it's really unstable then look for nose down canards at low speed/modest nose up at rotation. If it's more stable, the canards will be giving more lift in most flight regimes, to balance the aft wing. And if it's more stable, it's more of a strike platform IMHO.

Also, I'm not sure the main doors can close when the u/c is down as the chevrons on the main and aft u/c doors would need to line up, and possibly can't with the aft doors open. That may rule out carrier/rough field ops.

Can't wait to see it fly!

 

[mboeller]

I think that, even with lots of canard/forebody lift, that would still make it a less than ideal dogfighter. I think this is a big, twin engine, stealthy SAAB Viggen. Strike/secondary interception, with a wide C. of G. range for carrying/trimming diverse, heavy stores.

What about reconnaissance? this was not mentioned in the thread, I think.

combine it with the Fend Dong 21D....

 

[Foxglove]

Abraham, I weigh my words here and would appreciate if you did the same. If the difference in nozzles between the WS-10/15 and the AL=31F is to you all about different lighting conditions, then I refrain from further comments.
I do not think my opinion regarding the use of different engine types is premature: I analyze photographs and draw logical conclusions which of course could be wrong, I never claimed any different. Nonetheless, instead of throwing at each other dismissive remarks , I suggest we stick to facts.

 

[Trident]

I'm with Deino and Foxglove on this, something about the nozzles appears to have changed. This could be as mundane as them having been cleaned and polished (like the Thunderbirds do on their Vipers) or it could be something more interesting. If lighting or colour balance was the reason for the difference I would expect the rest of the aircraft and the entire scene to look noticeably different as well and I'm not seeing this. It seems unlikely that there is a second airframe though, the top photo among the last three Deino has posted shows the "new" nozzles but the bort number is still 2001 which pretty much rebuts the engine change hypothesis.

So my guess is polished nozzles for the upcoming special occasion with many highly ranked officials in attendance. Look at the stupid uniforms they seem to have made the ground crews wear, it wouldn't surprise me at all

 

[sferrin]

;D

So where are those video clips shown in the pictures?

 

[flanker]

http://centurychina.com/plaboard/posts/3882311.shtml

A bit confused regarding the nozzles.

 

[Yamachoma]

Well, more sharp eyed guys than me noted that 'J-20 cockpit' is surely a fake and belongs to F-35 mockup - as it was exhibited in 2005 at Bourget
www.youtube.com/watch?gl=US&client=mv-google&hl=en&v=sHJMIOlHt1U
Didn't ever know that Lockheed did some facelifting job since then.

;D Nice Job!!!, then it looks the first one or the third one could be the finalists or someothers

 

[Yamachoma]

Press People on Site means ???

 

[F-14D]

http://centurychina.com/plaboard/posts/3882311.shtml

A bit confused regarding the nozzles.

Maybe we are not looking at different engines at all, just different nozzles. We do not actually know the chronological order in which these pictures were actually shot, which can cause confusion. The thrust vectoring nozzles wouldn't be necessary for all of the taxi and ground run tests. Possibly they weren't quire ready and they had a schedule to meet. Could it be that some of the shots are of the aircraft with conventional nozzles for ground testing, and as the first flight approaches the more representative nozzles have been installed?

 

[Yamachoma]

Upper two WS10A

Lower two AL31FN

 

[Trident]

Maybe we are not looking at different engines at all, just different nozzles. We do not actually know the chronological order in which these pictures were actually shot, which can cause confusion. The thrust vectoring nozzles wouldn't be necessary for all of the taxi and ground run tests. Possibly they weren't quire ready and they had a schedule to meet. Could it be that some of the shots are of the aircraft with conventional nozzles for ground testing, and as the first flight approaches the more representative nozzles have been installed?

Possible, but there are some shots with the "new" nozzles where you'd expect the engines to be powered down and hence the nozzles to droop under gravity, but they don't.

 

[overscan (PaulMM)]

http://centurychina.com/plaboard/posts/3882311.shtml

A bit confused regarding the nozzles.

Maybe we are not looking at different engines at all, just different nozzles. We do not actually know the chronological order in which these pictures were actually shot, which can cause confusion. The thrust vectoring nozzles wouldn't be necessary for all of the taxi and ground run tests. Possibly they weren't quire ready and they had a schedule to meet. Could it be that some of the shots are of the aircraft with conventional nozzles for ground testing, and as the first flight approaches the more representative nozzles have been installed?

Maybe Chengdu stripped the discoloured petals off the engine and put new ones on so it looks shinier for the first flight pics. My point is, conjecturing additional prototypes and engine changes seems overly complicating the situation.

 

[Deino]

As such ... lets wait and see !

Anyway THIS is clearly an AL-31FN.

So long and let's hope for tomorrow ...

Deino

 

[Yamachoma]

As such ... lets wait and see !

Anyway THIS is clearly an AL-31FFN.

So long and let's hope for tomorrow ...

Deino

The pic is still not clear enough, From outter side, the AL-31 Series should have two clearly visible "Fin Pad" Segments, however, the "Fin Pad" on J20 Seemed to have one "Fin" Segments only, you can compare it with the one on J10 I posted above.

 

[Deino]

The second one is only st deeper behind ... but the first picture You posted is not a regular FN:

Deino

 

[PAK FA]

The views from above show that the entire main wing is behind the C. of G. (which has to be ahead of the mainwheels)

I agree with you the main wing is positioned well behind the center of gravity, this has to make the aircraft quit stable and not as maneuvrable as the other two fifth generation fighters, the F-22 and T-50, this aircraft starts to look more and more like an interceptor.

 

[saintkatanalegacy]

hmmm... looks like my last drawing is very close to the actual aircraft