Chengdu J-20 pictures, analysis and speculation Part I

[siegecrossbow]

Thnx to everyone for support and feedback!

Very interesting... thank you for the effort in translating it, siegecrossbow! The paper does seem to foreshadow the J-20 configuration in many respects - even the afterbody sketch in figure 6 is not unlike the finished product. Was this article in the public domain before the first flight of the J-20? If so, the cranked wing trailing edge that figure could also explain why many expected it to have a "lambda wing".
BTW, I think what you called "wing bending mechanisms" may be what is referred to as variable camber in English jargon.

I don't have much experience in the field of aerodynamics and I had to improvise for some of the aerodynamic terms. Thnx for the fix! The article in question was first published in 2001 and was in public domain long before the J-20 prototype came out in Dec. 2010.

Siegecrossbow, I'm not a pro nor an aerodynamicist (have picked up a thing or two here and there), but that made very interesting technical reading. Save for the intakes perhaps, those principles seem to have been carried through to J-20. Makes me wonder what might be found around the public domain about 6th gen fighters; anything like this and we could approximate the next "J" years before it appears at the end of the Chengdu runway.

There is an article published by an engineer from CAIC talking about how a flying wing design is the best choice for a sixth gen fighter. It is a lot less academic than Dr. Song's article. There was also another article (published in a magazine, I believe) by a professor from the Beijing Aeronautics and Space University talking about the characteristics of 6th gen fighters (some of which included A.I and onboard DEW. If I have time I will translate them.

 

[Reaper]

Hi! Also from my side thanks for translating.
Actually I dont understand why the author of the article focusses so much on high lift for a delta canard configuration. The statement for example that a canard increases lift in high AOA, is useless, because the purpose of the control canard would be to control the aircraft at high AOA and not increasing the lift where it is not needed. cheers R

 

[kulus]

Interesting video, mainly under the flap J-20 engienes

http://www.youtube.com/watch?v=i0HQUfGKDkg&feature=player_embedded

 

[Dragon029]

Twin outlets for the APU / bleed air I presume?

 

[kulus]

I have no idea what it is ?

 

[Machdiamond]

99% sure it is the Jet Fuel Starter exhaust.

 

[Deino]

 

[rousseau]

Here is mine

 

[chuck4]

So is there any major difference between the two?

 

[Deino]

So is there any major difference between the two?

You mean both prototypes !??

As far as we've noticed, there seems to be - besides the slightly higher set PLAAF-star on the tail - a strange "thing" behind the canopy (but that could also be onl ya removed panel !) and it seems as if the pitot is different.

This was from today:

http://www.youtube.com/watch?feature=player_embedded&v=FBn2h1CnnZI

Deino

 

[siegecrossbow]

There is news on CJDBY that the second prototype may taxi and fly soon. Stay tuned.

 

[Reaper]

Did somebody post already this J-20 flying with JF-17 video? Found on the DEW line:

http://www.youtube.com/watch?v=j5WXayZBMeo&feature=player_embedded

check out the visitors group on the aircraft!

 

[Deino]

2002 started with the taxi test .....

 

[Deino]

... only the best from today ...

http://www.56.com/u/v_NjgxOTI5MTU.html

 

[RSF]

Another photo of 2001-2 and 2002 sitting next to each other on the tarmac. How long will it be before we see both in the air together for a photo op?!

 

[Deino]

Another photo of 2001-2 and 2002 sitting next to each other on the tarmac. How long will it be before we see both in the air together for a photo op?!

I think not as soon as we might hope since no. 2001 was moved to Yanliang (according to wall climbers on CJDBY). The plane didn't land after it took off yesterday ... so we can assume, the next phase of flight testing to begin ! ... which however will mean we won't see them as often as during the last months.

As such these photos added were from yesterday but posted only today.

Deino

 

[RSF]

I'm not sure if its just the camera angle but tails/ruddervators on 2002 look like they're slightly longer/shaped different at the top? I went back to the photos of the two sitting next to each other but its hard to tell with the quality of these pictures.

 

[Deino]

I'm not sure if its just the camera angle but tails/ruddervators on 2002 look like they're slightly longer/shaped different at the top? I went back to the photos of the two sitting next to each other but its hard to tell with the quality of these pictures.

Hmmmm ???

 

[sferrin]

Angle of stabilizer. One is rotated towards the camera, the other away from the camera. That combined with the location and axis of the pivot make them look different. They do have different probes up front though. Looks like the door to the chute compartment might be different too.

 

[RSF]

Absolutely, the tails are pointed away from the camera in one photo and towards the camera in the other which changes the perspective and could account for what looks different.

Still, when I first saw 2002 taxing the first thing I thought was that the stabilizers looked slightly different/larger. Only time and better photos will tell.

http://alert5.com/wp-content/uploads/2012/05/211514cdp95lrdm6lcxmjd1.jpg

 

[The Artist]

Another thing to consider is the placement of the star on the stabilizer. While there could be a difference in stabilizers between the two aircraft, it is also possible that the eye (and brain) is being fooled by this shift in placement. The star is the dominant landmark on the stabilizer so the brain can't help evaluating the position of the edges in relation to the star to determine the shape. Try comparing after painting out the star in both pictures.

 

[rousseau]

Pay attension to the difference of air-intake's lip!

 

[flateric]

Pay attension to the difference of air-intake's lip!

this is intake cover pulled in and fixed by scotch tape

 

[flanker]

Pay attension to the difference of air-intake's lip!

People are still being fooled by this?

 

[saintkatanalegacy]

even the slightest difference in shot angle and field of view does create some optical illusion making it appear as if it had variable geometry intake lip.

 

[overscan (PaulMM)]

Pay attension to the difference of air-intake's lip!

this is intake cover pulled in and fixed by scotch tape

+1

 

[Sundog]

The difference in the angle of the all moving tails is called, "hydraulic fluid."

You see, in one pic, the plane is taxiing under power, with all the systems up and running and in the other, the aircraft is being towed without it's systems running.

Or to put it another way; in one pic the airplane is turned "on," and in the other, it is turned "off."

 

[rousseau]

Pay attension to the difference of air-intake's lip!

People are still being fooled by this?

What I mean was not VG lip or fixed lip, don't you remember the difference of lip on 2001 type? Something asymmetric not by shape but structure.....

 

[Deino]

... from today ...

 

[RSF]

Have a look at this comparison shot of 2001-2 vs. 2002 from the front. It looks like the ventral fins on the underside of the aircraft are slightly larger and now extend just below the rear wheel doors vs. 2001.

 

[LowObservable]

Not sure, RSF - If you look very closely, the viewpoint in the upper pic is a tidge lower (looking up at the nose) than the lower pic, and that might be all the difference to create that effect.

Actually, the lack of difference between the two aircraft makes them look even less like X-planes than they did before.

 

[Stargazer]

Here is a small animation I made of the two right hand side views of "2001" and "2002" as presented in the previous page. There doesn't seem to be any noticeable difference apart from the position of the pitot tube in the nose.

 

[SpudmanWP]

Here is a good closeup view of the two different tube locations:

http://is.gd/4sG2mv

 

[Deino]

A nice psed image ...

Anyway this might be a picture at CAC in a few years. B)

 

[The Artist]

Have a look at this comparison shot of 2001-2 vs. 2002 from the front. It looks like the ventral fins on the underside of the aircraft are slightly larger and now extend just below the rear wheel doors vs. 2001.

Long lens (telephoto lens) effect going on here. Those fins may be the same length on both aircraft yet look like this. If the planes were the same distance from the photographers and you got this difference then yes, the fins are of different length. If, as is likely, one of the planes was closer, then geometry (perspective) would change the apparent relationship between the fins and the gear doors. In using the gear doors as the unit of measure the fins would appear to be shorter on the closer plane.

 

[Deino]

Congrats to CAC ... 2002 has just landed following its maiden flight !

Photos hopefully later ... Took off at 14:49, landed 15:07 !

Deino

 

[overscan (PaulMM)]

Probably time to lock this topic and start a new one? 46 pages long...

 

[flateric]

but before...
via =GT @CDF

 

[Deino]

... ok ...

 

[Deino]

Videos from the first flight of 2002:

View: http://www.youtube.com/watch?feature=player_embedded&v=9LU6HkY7ews

View: http://www.youtube.com/watch?v=HaNqFsDU8lo&feature=relmfu


Deino