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Author Topic: Chengdu J-20 pictures, analysis and speculation Part II  (Read 348337 times)

Offline PaulMM (Overscan)

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Chengdu J-20 pictures, analysis and speculation Part II
« on: May 21, 2012, 06:31:08 pm »
New topic please...
"They can't see our arses for dust."
 
- Sir Sydney Camm

Offline Wil

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #1 on: May 26, 2012, 06:23:45 pm »
Hi!

J-20/Su-35 engine size comparison



J-20/Su-30 size comparison



Good luck!

Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #2 on: May 26, 2012, 07:31:43 pm »
Hi!

J-20/Su-35 engine size comparison



J-20/Su-30 size comparison



Good luck!


Not sure what you're speculating about.
"DARPA Hard"  It ain't what it use to be.

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #3 on: May 27, 2012, 12:29:45 am »
Me too !??  :o ::)

IMO the one on top is difficult to use (does it have the same scale ??), since it seems only to have scaled the nozzle diameters to the same size.

On the other side that's not a real problem since - even if we still don't have clear shots of the AB-arrangement like flameholder and so on - I'm convinced that CAC once again turned to Saturn to use an AL-31FN vesion.

Deino
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline Wil

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #4 on: May 27, 2012, 01:00:58 pm »
...since it seems only to have scaled the nozzle diameters to the same size.

Deino


That's the idea!
We assume that both aircrafts have Russian engines such as Al-31.
The J-20 truly has a great size.

Wil

Offline PaulMM (Overscan)

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #5 on: May 27, 2012, 05:53:28 pm »
Bad choice of pictures lead to bad assumptions. Are the exhausts both open to the same angle?


We've been over this before, I see nothing interesting or useful in your pictures to add to the previous calculations done.
"They can't see our arses for dust."
 
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Offline SOC

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #6 on: May 27, 2012, 08:58:18 pm »
I see nothing interesting or useful in your pictures
Hold on now, that second picture is great.
It shows 2002, the second prototype.  Which means you can now claim that there are two flying J-20s and actually be credible when you do so.

Offline flanker

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #7 on: May 28, 2012, 01:44:04 pm »
What? Have you seen the last thread? It is full of 2002 pics at the end.
Push the envelope,watch it bend.

Offline SOC

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #8 on: May 28, 2012, 02:27:24 pm »
What? Have you seen the last thread? It is full of 2002 pics at the end.

Dude, your sarcasm detector is broken.  Might want to check the batteries  ;D

Offline PaulMM (Overscan)

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #9 on: May 28, 2012, 08:23:30 pm »
Sean was alluding to the overheated "two prototypes" discussions when the first prototype was unveiled.
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Offline flanker

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #10 on: May 29, 2012, 10:57:36 am »
Ah, i see.
Push the envelope,watch it bend.

Offline siegecrossbow

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #11 on: June 02, 2012, 10:56:56 am »
Second flight of 2002:


Offline consealed

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #12 on: June 03, 2012, 06:12:20 am »
Nothing special. B)
The key to any great story not is who or what, when or where, but why

Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #13 on: June 03, 2012, 06:38:06 am »
Whenever I see J-20 videos I can't help but wonder if the residents know what a blue sky looks like.
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Offline siegecrossbow

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #14 on: June 03, 2012, 03:33:50 pm »
Whenever I see J-20 videos I can't help but wonder if the residents know what a blue sky looks like.

Part of it has something to do with air pollution but the climate in Chengdu is mostly responsible for the foggy weather.

Offline RSF

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #15 on: June 08, 2012, 07:14:35 am »
Whenever I see J-20 videos I can't help but wonder if the residents know what a blue sky looks like.

Obviously you've never lived in Seattle, it all looks perfectly normal to me! :)

Offline Steve Pace

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #16 on: June 08, 2012, 07:34:28 am »
Whenever I see J-20 videos I can't help but wonder if the residents know what a blue sky looks like.

Obviously you've never lived in Seattle, it all looks perfectly normal to me! :)
Or in Tacoma! -SP
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Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #17 on: June 13, 2012, 10:07:01 am »
Test flight on 12 June 2012 ...

He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline Gridlock

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #18 on: June 13, 2012, 04:38:10 pm »
I still can't quite mentally reconcile China, land of the execution van and forced labour with China, where you can film this sort of thing and stick it on YouTube.


And what's with the flexible tail?  :o

Offline Sea Skimmer

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #19 on: June 14, 2012, 12:13:52 am »
You can film it because China wants it to be filmed as proof of how powerful they are becoming. Its not like they couldn't have been doing all of this at an isolated base had they wished.

Offline Gridlock

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #20 on: June 14, 2012, 12:56:08 am »
So get the guy off the stepladder and build a planespotter stand already :)

Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #21 on: June 14, 2012, 05:56:33 am »
So get the guy off the stepladder and build a planespotter stand already :)

And get him a decent camera.  I'm tired of the Keystone Cops jerky framerate.
"DARPA Hard"  It ain't what it use to be.

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #22 on: June 14, 2012, 06:25:03 am »
... at least these are slightly better !
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #23 on: June 15, 2012, 06:02:31 am »
Is this photo ok ???  :o
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline saintkatanalegacy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #24 on: June 15, 2012, 03:05:40 pm »
Looks all right. Reveals some lines and rivets. A bit more of quality shots and we'll probably get some good panel shapes
風 Swift as the wind
林 Quiet as the forest
火 Conquer like the fire
山 Steady as the mountain

Offline consealed

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #25 on: June 15, 2012, 09:04:56 pm »
It looks no difference from 2001.
The key to any great story not is who or what, when or where, but why

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #26 on: June 16, 2012, 02:19:08 am »
It looks no difference from 2001.

Sorry if my comment was misleading and You are correct that besides that new pitot and the ability to close the MLG dors while taxying the only "new" observation is this yellowthink with these <> corners.

Otherwise I think this shape is interesting ... but again not new !
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline Foxglove

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #27 on: June 16, 2012, 04:59:08 am »
Hey, correct me if I'm wrong, but in the final few seconds of the video posted by Deino ( many thanks) you can see the backs of as many as FOUR J-20s lined up :o !


Offline Trident

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #28 on: June 16, 2012, 07:13:43 am »
Sorry if my comment was misleading and You are correct that besides that new pitot and the ability to close the MLG dors while taxying the only "new" observation is this yellowthink with these <> corners.

It is quite possible that this part already exists on #2001 but was painted black from the outset and therefore not as visible.


Otherwise I think this shape is interesting ... but again not new !


That notch in the nose mold line is probably where the forward-looking MAWS sensor is located, IMHO.

Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #29 on: June 16, 2012, 08:48:35 am »
Hey, correct me if I'm wrong, but in the final few seconds of the video posted by Deino ( many thanks) you can see the backs of as many as FOUR J-20s lined up :o !

Photoshop is amazing isn't it?
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Offline Foxglove

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #30 on: June 16, 2012, 11:57:47 pm »
Hey, correct me if I'm wrong, but in the final few seconds of the video posted by Deino ( many thanks) you can see the backs of as many as FOUR J-20s lined up :o !

Photoshop is amazing isn't it?
You can't exclude it, but when the first photos of  the J-20 surfaced, many, including me, suspected PS might've been employed. Please note it hasn't been settled unequivocally yet whether a/c no. 2001 had two differrent engine types fitted, or there were/are two different examples bearing the same bort number. If the latter is true, we already have at least three examples. And how long was it before Chinese authorities officially admitted the existence of the J-20 after the type's photos flooded the net? When it comes to military technology, the official story is usually far behind the current state of affairs.
« Last Edit: June 17, 2012, 12:20:58 am by Foxglove »

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #31 on: June 17, 2012, 01:57:45 am »
Hey, correct me if I'm wrong, but in the final few seconds of the video posted by Deino ( many thanks) you can see the backs of as many as FOUR J-20s lined up :o !

Photoshop is amazing isn't it?

Yep ... was already posted in the first tread !

http://www.secretprojects.co.uk/forum/index.php/topic,11768.msg151931.html#msg151931
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline consealed

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #32 on: July 16, 2012, 05:38:23 am »
 :P
The key to any great story not is who or what, when or where, but why

Offline consealed

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #33 on: July 20, 2012, 08:54:53 pm »
one more side view

The key to any great story not is who or what, when or where, but why

Offline siegecrossbow

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Offline siegecrossbow

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #35 on: August 05, 2012, 07:04:02 pm »
While every one is still focused on the olympics:

http://www.56.com/u76/v_NzA3MjQwODE.html

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #36 on: August 07, 2012, 12:14:47 am »
Olympics ?? ... there are Olypics at the moment ??

Here are two quite recent images  :-*
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline Wil

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #37 on: August 16, 2012, 12:42:31 pm »
Hi!!!

A new comparison Su-35 / J-20.

 B)

Offline Demon Lord Razgriz

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #38 on: August 28, 2012, 06:54:16 pm »
Bit off topic here, but relevant.

I was going through an old flash drive of mine when I came across this picture:


Last time I used this flash drive was several years ago before the J-20 was revealed, but it matches almost perfectly the center plane. The upper plane is that new Trainer the Chinese have, but I'm more interested in the lower one, which seems to line up well with that plane we've seen pictures of on the highways. Could this image have been a leak years ago from maybe a Chinese PowerPoint showcasing the future PLAAF airfleet? Just seems too creepy with how things have lined up so far.

Offline donnage99

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #39 on: August 28, 2012, 07:00:55 pm »
I doubt it.  The j-20's shape has been circulating around the web under the term j-xx years before the unveiling. 

Offline PaulMM (Overscan)

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #40 on: September 16, 2012, 04:32:12 am »
Nice pics with J10S.
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Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #41 on: September 17, 2012, 06:50:07 pm »
Why do so many pictures appear to show j-20 with its two all moving vertical tails cocked at wildly different angles?


One would think those tails would either deflect in unison or deflected in mirror symmetry.

Offline famvburg

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #42 on: September 18, 2012, 08:38:26 am »

  They're probably hydraulic and with no pressure they just flop. IIRC, F-18s do the same.

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #43 on: October 19, 2012, 11:21:22 pm »
Some members of different forums in China are discussing if 2003 has been "rolled-out" ....   ???
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline TAKHISS

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #44 on: October 20, 2012, 04:41:00 am »
J-20 #2003

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #45 on: October 20, 2012, 05:02:46 am »
I agree ...  IMO this is for sure a new prototype !
Deino
« Last Edit: October 20, 2012, 12:33:42 pm by PaulMM »
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #46 on: October 20, 2012, 11:22:48 am »
This one looks like it has a real nose radom.  So it probably has a working radar.   The bulkhead behind the radar, if delineated by the break in color on the fuselage, seem to lean backwards.   That would seem like a characteristic of an AESA radar.    Also there seems to be a diamond shaped, upward facing window right ahead of the canopy.  Probably some part of a distributed aperture sensor.  If it were a simple IRST, it won't face up.    I would think this thing is not a prototype but a production-development aircraft.

Offline PaulMM (Overscan)

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #47 on: October 20, 2012, 01:17:52 pm »
Played around in GIMP trying to enhance details.
"They can't see our arses for dust."
 
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Offline Deino

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He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline fightingirish

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #49 on: October 21, 2012, 10:45:14 am »
With the panels opened, it reminds me very much of that fake CGI from a few years ago.  ;)
Slán,
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Offline dark sidius

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #50 on: October 21, 2012, 01:58:32 pm »
The size of this thing is huge
 

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #51 on: October 21, 2012, 02:18:29 pm »
The access panels do not appear to have serrated edges.

Offline flanker

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #52 on: October 21, 2012, 03:18:15 pm »
The access panels do not appear to have serrated edges.

And how many panels did on YF-23 and X-35 for instance? It is prototype, same thing for most part on PAK FA as well.
Push the envelope,watch it bend.

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #53 on: October 21, 2012, 11:30:01 pm »
 ;)
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #54 on: October 22, 2012, 01:37:35 pm »
 
The big hatch right behind the cockpit seems very sturdy and capable of being opened in flight.  An hitherto unseen airbreak?
 
If the arrangement of access panels and avionics bays near the cockpit is similar to production aircraft, then that suggest no space is being reserved for any cheek mounted radar, unless the radar is actually in the bump of the deflectorless inlet.
 
And yes, the covers for the two access hatches under the forward fuselage has no serration, but the one immediately behind the radar bulkhead does.
 
Also the avionic service access panels under the chine seems to remove completely instead of hing out of the way.   This suggest development aircraft could use some maintenance accessibility enhancements.
« Last Edit: October 22, 2012, 01:47:15 pm by chuck4 »

Offline Sundog

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #55 on: October 22, 2012, 07:16:54 pm »

The big hatch right behind the cockpit seems very sturdy and capable of being opened in flight.  An hitherto unseen airbreak?
 

It is an air brake and it has been seen in flight on the second prototype.

Offline flateric

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #56 on: October 22, 2012, 11:05:34 pm »
It is an air brake and it has been seen in flight on the second prototype.
...as early as June, 2011
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Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #57 on: October 22, 2012, 11:15:17 pm »
Yepp... rarely seen in the open position, but alreay there since the beginning !
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline Sundog

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #58 on: October 23, 2012, 10:42:10 am »
Thanks, I never noticed it in my images of the first prototype.

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #59 on: October 25, 2012, 05:02:43 am »
I agree ...  IMO this is for sure a new prototype !
Deino

Shame on me ....  :-\ :-[
 It seems as if the conclusion about a third prototype was made a bit too early !  :o  Following these images it is in fact still the second aircraft no. 2002, which was - at least it seems so  ??? - "simply" re-equipped with the radar ! (even if image 2 looks strange to me)

Deino
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline flanker

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #60 on: October 26, 2012, 04:38:36 pm »
"simply" re-equipped with the radar !
Deino

Who says so?

(even if image 2 looks strange to me)

It is obvious PS job with pitot removed and the outline of the new nose shown in a different color.
Push the envelope,watch it bend.

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #61 on: October 27, 2012, 05:22:46 am »
Who says so?

No-one !!! Its an - IMO logical - assumption based on reports, rumours, images of the prototype several days agao with a new radome and work on the avionics and the assumption based on comparisons to ther programs. It surely can be a simply repainted radome to fool us all here but based on what we have it's not too far fetched to assume that the prototype received a radar.
Similar assumptions are done for the T50-3 which is "said" to be equipped with a radar too ... but since the radar itself is not shown I agree with You we have no confirmation on that.
 
Deino
 
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #62 on: October 27, 2012, 08:47:58 am »
Why was my observation that j-20's radom appeared to be larger than f22's, signifying a larger aperture AESA, deleted?

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #63 on: October 28, 2012, 01:11:51 am »
Actually I don't know ??????
 
Another mystery from today .... IFR-probe or psed again ???
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline flanker

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #64 on: October 28, 2012, 04:06:56 am »
No-one !!! Its an - IMO logical - assumption based on reports, rumours, images of the prototype several days agao with a new radome and work on the avionics and the assumption based on comparisons to ther programs. It surely can be a simply repainted radome to fool us all here but based on what we have it's not too far fetched to assume that the prototype received a radar.
Similar assumptions are done for the T50-3 which is "said" to be equipped with a radar too ... but since the radar itself is not shown I agree with You we have no confirmation on that.
 
Deino

Don't get me wrong, i don't disagree with what you said here.  :) When it comes to T-50-3, i think it having a radar is a bit more trustworthy than 2002 having one. As of now anyway.

IFR pic definitely could be real. There is a panel there. Also, some has said there is new "panels" (with stealthy "teeth") around the nose, imho, they are not new, they are just seen more clearly after the new radome was fitted.
Push the envelope,watch it bend.

Offline PaulMM (Overscan)

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #65 on: October 28, 2012, 05:06:24 pm »
No-one !!! Its an - IMO logical - assumption based on reports, rumours, images of the prototype several days agao with a new radome and work on the avionics and the assumption based on comparisons to ther programs. It surely can be a simply repainted radome to fool us all here but based on what we have it's not too far fetched to assume that the prototype received a radar.
Similar assumptions are done for the T50-3 which is "said" to be equipped with a radar too ... but since the radar itself is not shown I agree with You we have no confirmation on that.
 
Deino

Don't get me wrong, i don't disagree with what you said here.  :) When it comes to T-50-3, i think it having a radar is a bit more trustworthy than 2002 having one. As of now anyway.

IFR pic definitely could be real. There is a panel there. Also, some has said there is new "panels" (with stealthy "teeth") around the nose, imho, they are not new, they are just seen more clearly after the new radome was fitted.

Could be a new radome plus equipment to test it with. Assuming its a radar is a big leap, especially with the pitot tube still in place - hard to reconcile with an AESA.
"They can't see our arses for dust."
 
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Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #66 on: October 28, 2012, 05:37:51 pm »
Just what kind of radarless radar radome testing requires a lot of equipment that must fly with radarless radome  on a plane?    It seems to me most testing that can be without the radar are the sort of physical property testing that are better done on the ground.   The only major test that might  be better done in flight is to check whether it falls off?

Just why is pitot tube on the tip of radome more fundamentally Irreconcilable with AESA?

Pitot tubes are to be seen on the tip of radome of service fighters equipped with PESA, mechanically scanned, or hybrid radar antennas.

Also, why is AESA radar a large leap for j-20?   No one made a big fuss when j-10B was seen with a AESA radar, minus the radome. 


« Last Edit: October 28, 2012, 09:11:44 pm by chuck4 »

Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #67 on: October 28, 2012, 07:17:22 pm »
No one made a big fuss when j-10B was seen with a AESA radar, minus the radome.
It was seen with what looked like an AESA radar.  Whether it was a bonified working example is another story entirely.
"DARPA Hard"  It ain't what it use to be.

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #68 on: October 28, 2012, 09:28:30 pm »
The Chinese deployed AESA arrays on the type 052C DDG in 2002.  They deployed airborne conformal AESA on a IL-76 based AWAC in 2008.   They clearly have possessed basic AESA technology long enough for considerable skill maturation.    It is reasonable to question the marginal performance and capability of their AESA radars, but it is silly to doubt their capacity to deploy a functioning instrument in a fighter.


The evidence that the radar under j-20's radome is actually AESA is not conclusive based on my knowledge.  I noted that the back edge of the radome, where it joins the fuselage, is sloped backwards.   This suggested the bulkhead on which the radar is mounted also sloped backwards.  This has been indicated by other commentators to be a characteristic trait of AESA.   But I wouldn't be able to tell you why AESA tends to be mounted on backward sloping bulkheads, and why other radar antennas tend not tobe.
« Last Edit: October 28, 2012, 09:56:00 pm by chuck4 »

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #69 on: October 29, 2012, 01:31:56 am »
From today ....
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline PaulMM (Overscan)

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #70 on: October 29, 2012, 03:38:24 am »
Just what kind of radarless radar radome testing requires a lot of equipment that must fly with radarless radome  on a plane?    It seems to me most testing that can be without the radar are the sort of physical property testing that are better done on the ground.   The only major test that might  be better done in flight is to check whether it falls off?


Lots of reasons why the radome could change colour and access panels be open. Maybe they just got the grey paint from the supplier and are checking the radar still works OK with it on. Maybe they fitted a new radome for flight testing and are retrieving vibration sensor readings. Who knows?


"Being fitted with new radar" seems unsupported by photographic evidence at this stage. Show me a radar being fitted :)




Just why is pitot tube on the tip of radome more fundamentally Irreconcilable with AESA?

Pitot tubes are to be seen on the tip of radome of service fighters equipped with PESA, mechanically scanned, or hybrid radar antennas.


Because the nose is a great location for a pitot tube, for most accurate measurement, but the worst place to put it for radar performance. Its a physical obstacle in the way of the radar, causing unwanted reflections and line of sight blockage, reducing stealth. Noone in their right minds designing a stealthy aircraft with high performance radar would put it there except on a prototype where measuring airspeed etc is more relevant than radar performance.

Also, why is AESA radar a large leap for j-20?   No one made a big fuss when j-10B was seen with a AESA radar, minus the radome.


I expect J-20 to have AESA. I also expect the nose pitot to be deleted from later J-20s, once radar performance and RCS are being tested.
"They can't see our arses for dust."
 
- Sir Sydney Camm

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #71 on: October 29, 2012, 06:42:38 am »
 :o
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #72 on: October 29, 2012, 07:18:49 am »
The pre-production F-22s built after 1997 still had prominent air data probes at the tips of their radomes, in conjunction with otherwise production type radomes.   When did the first f-22 with operational radar fly?

Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #73 on: October 29, 2012, 07:55:13 am »
The Chinese deployed AESA arrays on the type 052C DDG in 2002. 

Uhm, no.  Those aren't AESAs. 
"DARPA Hard"  It ain't what it use to be.

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #74 on: October 29, 2012, 09:03:17 am »
Uhm, yes, they are.

Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #75 on: October 29, 2012, 09:09:15 am »
Uhm, yes, they are.

According to Wiki it looks like you might be right.  I'd prefer a source a little more reputable myself though.
« Last Edit: October 29, 2012, 09:18:13 am by sferrin »
"DARPA Hard"  It ain't what it use to be.

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #77 on: October 29, 2012, 09:46:02 am »
By the way - I was curious, given the negative effects of the ventral stakes on low observability - what flight regime is likely to require them?

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #78 on: October 29, 2012, 09:57:59 am »
High AOA.   Given the length and configuration of the J-20, and the relatively small size and low height of the rudder/stabilizer, J-20's rudders would probably be ineffective in high AOA and the aircraft would have yaw stability issues without ventral stakes.
 
I am guessing the roadmap for the J-20's development includes deleting the ventral strake after adding 3-D TV
« Last Edit: October 29, 2012, 10:01:03 am by chuck4 »

Offline Sundog

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #79 on: October 29, 2012, 10:47:12 am »
Any yaw issues they have at high AOA may not require 3D TV to solve. They may be able to do that with the canards alone. But, given that it's still flying with the nose pitot, they may just need them while they calibrate the FCS.

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #80 on: November 01, 2012, 09:11:07 am »
 ;)
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #81 on: November 01, 2012, 12:31:51 pm »
Just noticed the thing has at least 4 other pitot tubes besides the one at the tip of the nose radome.  2 below the radome, two besides cockpit. 
 
It also seem to have a small angle of attack sensor sticking out the side of the nose radome.
 
This suggest the flight control system needs a lot of air data to compare, and the plane is more unstable than is usual.
 
What I thought was a window for distributed aperture sensor right in front of the cockpit, it's not there in this better picture.     
 
There is still that diamond shaped window on the side the fuselage behind the radome.   May be part of MAW system?
 
I also notice the side of the acturator blisters under the wings for the flapperons don't merge into the wing at the same angle as fuselage side as on the F-22.   Instead they seem to merge into the wing at close to 90 degrees.   So at least in this part they didn't pay as much attention to stealth as they might have.

 
 
« Last Edit: November 01, 2012, 12:38:52 pm by chuck4 »

Offline Triton

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #82 on: November 10, 2012, 09:42:10 pm »
Chengdu J-20 cockpit mockup on display at Airshow China 2012 2010.

Source:
http://chinesemilitaryreview.blogspot.com/2012/01/cockpit-of-j-20-mighty-dragon-stealth.html

IMAGE REMOVED: Believed it was taken at this year's China Airshow
« Last Edit: November 11, 2012, 06:41:29 am by DonaldM »

Offline Dragon029

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #83 on: November 10, 2012, 11:19:56 pm »
I think the weapons display is a bit off - it shows the rough outline of an F-22.

Offline lancer21

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #84 on: November 11, 2012, 06:31:19 am »
Perhaps this is a cockpit mock-up for J-31 then...

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #85 on: December 06, 2012, 12:40:23 pm »
Can anyone please explain me how on earch such a BS can make it into a JDW report ??? ?   :o

That's simply a J-20 RC model - and at least anyone who would do a bit of research would easily find out !  ??? - but to assume a twin engined VTOL-type being under development in China based on the J-20  :lol:  :oops:  .... what the hell became of Jane's ??? ??

Deino
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline Sea Skimmer

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #86 on: December 06, 2012, 12:53:57 pm »
Janes turned into a mere compiler of other peoples work and press releases long ago. Only the books they publish for other authors are any good anymore.

Offline flateric

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #87 on: December 06, 2012, 03:47:14 pm »
Perhaps this is a cockpit mock-up for J-31 then...
correct. it matches 1/4 scale model cockpit almost 100%
"There are many disbelievers in
stealth, more than a few of them truly technically ignorant and proud of it." Sherm Mullin, Skunk Works

Offline totoro

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #88 on: December 07, 2012, 01:04:24 am »

I also notice the side of the acturator blisters under the wings for the flapperons don't merge into the wing at the same angle as fuselage side as on the F-22.   Instead they seem to merge into the wing at close to 90 degrees.   So at least in this part they didn't pay as much attention to stealth as they might have.


Maybe they thought they're safe regardless of shape, if they made the better part of that blister, as you call it, of RA material. I really don't see any other reason why the actuator fairings are so huge. Even on j10, which has similar configuration and is cheaper design a was made 13 years earlier the actuators are much, much smaller. Even when taking into account larger plane and larger control surface, the actuators themselves don't have to be even a quarter of the size of fairings seen on j20. I am not saying it is so, but if one wanted to, one could easely fit 3-5 cm thick RA material on each side of that actuator within that fairing size limit.
www.youtube.com/c/binkovsbattlegrounds - military analysis videos

Offline PaulMM (Overscan)

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #89 on: December 21, 2012, 04:01:51 pm »
Nice
"They can't see our arses for dust."
 
- Sir Sydney Camm

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #90 on: December 21, 2012, 06:05:13 pm »
What are those little stubs sticking out from the nose radome?  AOA sensors?

Offline 2IDSGT

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #91 on: December 21, 2012, 07:26:34 pm »
Pitot tubes (some of them).

Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #92 on: December 21, 2012, 09:00:09 pm »
;)

Dang. If that was higher res it'd be my new wallpaper.  Sweet shot.
"DARPA Hard"  It ain't what it use to be.

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #93 on: December 22, 2012, 03:57:07 am »
Pitot tubes (some of them).

The ones that bend around to point forward are pitot tubes.  The 4 that sticks out sideways from the radome can't be ordinary pitot tubes.    They seem to some other air data sensor that, judging from their location, are part of the airplane's permanent equipment, not just flight test suite.

Offline 2IDSGT

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #94 on: December 22, 2012, 04:50:40 am »
Pitot tubes (some of them).
The ones that bend around to point forward are pitot tubes.  The 4 that sticks out sideways from the radome can't be ordinary pitot tubes.    They seem to some other air data sensor that, judging from their location, are part of the airplane's permanent equipment, not just flight test suite.
They could be directional sensors of some kind to feed data to the flight computer, but they look too delicate to be a permanent part of the flight control system (easily damaged by ice or other rigors).  Their positioning also seems awkward in relation to where one might assume the radar goes.  We'll just have to see if the things disappear later on to be sure.

Offline Dragon029

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #95 on: December 22, 2012, 05:50:37 am »
Zoom in and it's very easy to see that they're AoA sensors; swept angular fins that sit on circular bases.

Undoubtedly, they'll be removed in later airframes, and would simply be there now for flight envelope testing.

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #96 on: December 22, 2012, 04:54:21 pm »
If they are temporary AOA sensors for test purposes only, then they would work better and more cleanly, and can be arranged more efficiently, on a long instrumented nose probe characteristic of many other prototype or development airframes,  instead on the side radome.




Offline Dragon029

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #97 on: December 23, 2012, 03:18:45 am »
You would imagine so, but with a lack of such sensors on the nose probe, I stand by my view.

If 2002 has a working radar, wouldn't having moving fins, in the centre of the array's FOV prove troublesome?

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #98 on: December 23, 2012, 08:20:36 am »
You would imagine so, but with a lack of such sensors on the nose probe, I stand by my view.

If 2002 has a working radar, wouldn't having moving fins, in the centre of the array's FOV prove troublesome?

Not necessarily.  The sensors are fairly close to the rear edge of the radome.  Due to stealth shaping of the radome edge, the rear edge of the radome on j-20 would not define the location of radar bulkhead.  The actual bulkhead must lie some small distance ahead of the radome edge.   So these probes on the radome might well be mounted near the radar bulkhead, and out of the field of view of the radar antenna.
« Last Edit: December 23, 2012, 08:23:33 am by chuck4 »

Offline Sundog

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #99 on: December 23, 2012, 07:36:35 pm »
The reason they're mounted in that arrangement is most likely because they're being used to calibrate the FCS. When the stealthy sensors replace them they work partly due to the pressure patterns around the nose and by knowing the pressure distribution with respect to alpha, sideslip, and q they can deduct where the aircraft is within its flight envelope.

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #100 on: December 24, 2012, 09:47:03 am »
The reason they're mounted in that arrangement is most likely because they're being used to calibrate the FCS. When the stealthy sensors replace them they work partly due to the pressure patterns around the nose and by knowing the pressure distribution with respect to alpha, sideslip, and q they can deduct where the aircraft is within its flight envelope.

That would make sense if the location of the current sensors are the same as those intended for future production pressure sensors.      If they are purely development sensors to provide calibration data on actual alpha and sideslip, then they would work better in a nose probe where the airflow is clean and undisturbed.
 

Offline Sundog

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #101 on: December 26, 2012, 08:22:13 am »

 
That would make sense if the location of the current sensors are the same as those intended for future production pressure sensors.      If they are purely development sensors to provide calibration data on actual alpha and sideslip, then they would work better in a nose probe where the airflow is clean and undisturbed.


I'm talking about calibration at their current locations. A nose probe can't do that, which is why that isn't what they are. The earlier prototypes had the nose probe for that purpose. Also, there are other ways you can do it without the nose probe, like the B-2 did with the drag drogue, but that's most likely just for subsonic speeds.

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #102 on: December 27, 2012, 03:25:05 pm »
Found at the SDF .... interesting satellite image  :o






Truely an interesting image but again the author forgot that Xi'an is not only the home of XAC but even more important the CFTE !!!
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #103 on: December 27, 2012, 04:00:29 pm »
Would be nice if they gave latitude and longitude

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #104 on: December 28, 2012, 09:08:49 am »
A larger version ....
He was my North, my South, my East and West,
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For nothing now can ever come to any good.
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Offline LowObservable

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #105 on: December 29, 2012, 07:57:07 am »
There's a lat/long on the document.

Offline Racer

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #106 on: January 01, 2013, 08:45:58 am »
I think this is a good photo to see that the J-20 is smaller than a J-11/15.
A rough estimate: length: 19.2...20.7m, span: 12.8...13.8m.

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #107 on: January 02, 2013, 03:30:00 am »
Once again - and hopefully finally in regard to "laarger than 23m !" -  I played around a bit with the latest image from Xi'an-Yanglian !

What do You think ?

Deino
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Offline LowObservable

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #108 on: January 03, 2013, 05:59:41 am »
Nice on. RAF Medmenham will be calling.

However, it is still important to remember that dimensions are not size. The J-20 is pretty monolithic from nose to jetpipe, while the Su has the skinny cobra-like nose in front and is all jetpipes and tails behind the wing.

Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #109 on: January 03, 2013, 06:23:11 am »
Wonder how the J-20s volume compares to a Foxhound or F-111.  There's probably a lot of fuel in that sucker. 
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Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #110 on: January 03, 2013, 09:58:58 am »
Much of the volume is undoubtedly taken up by serpentine intake ducts and the 3 internal weapon bays.   It's not clear how much is left for fuel.   Assuming the Chinese aim for similar overall lift characteristics in combat weight as other maneuverable fighters, one ought to be able to guess at its intended combat weight by making some assumptions about its fuselage lift characteristics (I imagine that to be similar to F-22, due to similar geometry) and looking the size of the wings.
 
My overall impression is the wings are not that large, compared to F-22, this suggests to me the aircraft isn't meant to be much heavier than F-22.  Also, both the thrust of WS-10 engines (~13,000 KgF with AB), and the rumored thrust of the rumored WS-15 engines (~18,000 KgF, presumably with AB), does not suggest this to be an exceptionally heavy fighter, unless the Chinese are willing to accept unusually low T/W ratio.   It suggests to me this fighter is about as heavy as F-22, possibly even a little lighter.
 
It's lengthy fuselage might suggest it is designed to either cruise or burst faster than F-22, or cruise supersonically on less thrust than F-22.
 
So I would guess either J-20 is lighter than everyone seem to think, or not meant to be very maneuverable by G4 or G5 fighter standards.   
 
 
 
 
 
« Last Edit: January 03, 2013, 10:13:53 am by chuck4 »

Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #111 on: January 03, 2013, 11:03:27 am »
Much of the volume is undoubtedly taken up by serpentine intake ducts and the 3 internal weapon bays.   It's not clear how much is left for fuel.   Assuming the Chinese aim for similar overall lift characteristics in combat weight as other maneuverable fighters, one ought to be able to guess at its intended combat weight by making some assumptions about its fuselage lift characteristics (I imagine that to be similar to F-22, due to similar geometry) and looking the size of the wings.
 
My overall impression is the wings are not that large, compared to F-22, this suggests to me the aircraft isn't meant to be much heavier than F-22.  Also, both the thrust of WS-10 engines (~13,000 KgF with AB), and the rumored thrust of the rumored WS-15 engines (~18,000 KgF, presumably with AB), does not suggest this to be an exceptionally heavy fighter, unless the Chinese are willing to accept unusually low T/W ratio.   It suggests to me this fighter is about as heavy as F-22, possibly even a little lighter.
 
It's lengthy fuselage might suggest it is designed to either cruise or burst faster than F-22, or cruise supersonically on less thrust than F-22.
 
So I would guess either J-20 is lighter than everyone seem to think, or not meant to be very maneuverable by G4 or G5 fighter standards.

The YF-22 had ~25,000lbs of internal fuel.  The J-20 has more internal volume than it did.
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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #112 on: January 03, 2013, 03:46:23 pm »
knowing more or less the dimensions of j20, one can superimpose the pice of it and f22 taken from the front and then one can tell the frontal cross section is pretty similar to one of f22. however, fuselage length difference is noticeable. f22 has quite an overhang of its control surfaces behind the engine nozzles. j20 has less of an overhang. all in all, j20 has fuselage that is easely 2 meters longer. Plus a more tapered belly towards the engine nozzles.


I would be surprised if j20 doesn't end up having at least some 4-5 cubic meters of internal fuselage volume more than the f22. Weapons bay seems to be some 20% bigger, so part of the extra volume is spent there. Perhaps ws15 engines are planned to be of somewhat greater dimensions... or/and they use more fuel per thrust given. who's to say. but the plane certainly has plenty of room for fuel. that is, of course, both good and bad at the same time.
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Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #113 on: January 03, 2013, 04:39:38 pm »
knowing more or less the dimensions of j20, one can superimpose the pice of it and f22 taken from the front and then one can tell the frontal cross section is pretty similar to one of f22. however, fuselage length difference is noticeable. f22 has quite an overhang of its control surfaces behind the engine nozzles. j20 has less of an overhang. all in all, j20 has fuselage that is easely 2 meters longer. Plus a more tapered belly towards the engine nozzles.


I would be surprised if j20 doesn't end up having at least some 4-5 cubic meters of internal fuselage volume more than the f22. Weapons bay seems to be some 20% bigger, so part of the extra volume is spent there. Perhaps ws15 engines are planned to be of somewhat greater dimensions... or/and they use more fuel per thrust given. who's to say. but the plane certainly has plenty of room for fuel. that is, of course, both good and bad at the same time.

I simply don't think the likely engine thrust and wing area suggests a versatile and maneuverable fighter capable of handling an exceptional internal fuel capacity.     

Offline kcran567

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #114 on: January 03, 2013, 07:27:21 pm »
Way back when the first J-20 pics came out, I thought stealthy interceptor/light bomber/anti-ship with a little bit of fighter agility in there too but not much. Depending on how big the bomb bay volume is. It's at least as big as the f-22s. A stealthy Mig-31/F-111 with some added agility.


Mig-31 type Interceptor to supercruise patrol those vast Chinese borders, anti-ship/anti US carrier, and some light stealthy bombing missions. Actually, the Chinese would deem the f-22 as inadequate for those functions. they wanted more fuel volume and a bigger weapons bay and they got it. but obviously they like the canard heritage of the j-10 and the frontal stealth aspect of the f-22. Its going to be perfect for their needs.


The j-31 if it gets to production will fill their low-end needs and export. the Chinese are doing really good commercially, and their aerospace industry is pragmatic and cost effective. They might even outsell the f-35 because of affordabilty. We will see. Makes me wonder what their next Gen design is going to look like.


As far as stealth, i would even say the J-20 is Stealthier than the Sukhoi T-50.

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #115 on: January 03, 2013, 11:07:09 pm »
Assuming the reference image I used to calculate wing area was fairly accurate, I arrived at these approximate figures for overall reference wing area based on the speculated dimensions provided above:

Length - Wing Area
19.2 meters (63 feet) - 71 square meters (763 square feet)
20.35 meters (66.75 feet) - 79.9 square meters (860 square feet)
20.7 meters (67.9 feet) - 82.6 square meters (889 square feet)

For comparison, the F-22 has a length of slightly above 18.9 meters (62 feet) and a wing area of 78.4 square meters (840 square feet).

If (and this is a big if) the J-20 has a similar weight per unit length as the F-22, the following wing loadings can be calculated. These figures may not be that unreasonable since the two are in roughly the same size range and have similar design elements (the boxy fuselage, closely-spaced engines, low aspect ratio wings, fixed inlets, internal weapons, same canopy, etc). Take note that I did some rounding with the numbers.

Length - Loaded Weight - Wing Loading

19.2 meters (63 feet) - 29,700 kilograms (65,400 pounds) - 418 kilograms/square meter (86 pounds/square foot)
20.35 meters (66.75 feet) - 31,500 kilograms (69,300 pounds) - 394 kilograms/square meter (81 pounds/square foot)
20.7 meters (67.9 feet) - 32,000 kilograms (70,500 pounds) - 387 kilograms/square meter (79 pounds/square foot)

You may have noticed that the larger values for length generate lower values for wing loading. Due to scaling laws, this is almost certainly incorrect. Using the square-cube law (and using the lowest length value as a baseline) more realistic wing loadings may be calculated:

Length - Loaded Weight - Wing Loading

19.2 meters (63 feet) - 29,700 kilograms (65,400 pounds) - 418 kilograms/square meter (86 pounds/square foot)
20.35 meters (66.75 feet) - 35,400 kilograms (77,900 pounds) - 443 kilograms/square meter (91 pounds/square foot)
20.7 meters (67.9 feet) - 37,200 kilograms (82,000 pounds) - 450 kilograms/square meter (92 pounds/square foot)

For comparison, the F-22's loaded weight is 29,300 kilograms (64,460 pounds) and its wing loading in this state is 375 kilograms/square meter (77 pounds/square foot). All of these estimates put it at a higher wing loading than the F-22. However, I would also like to point out the the range of wing loadings calculated is still rather "fighter-like". Compare these values with those of the F-16C Block 30 (at 431 kg/m2 or 88.3 lb/ft2), the F-35A (at 526 kg/m2 or 107 lb/ft2), the F/A-18E/F (at 459 kg/m2 94 lb/ft2), and the Su-35S (at 408 kg/m2 or 84.9 lb/ft2).

It should also be remembered that there are many other factors that affect an aircrafts lift than just wing loading alone. There is also leading edge sweep, taper ratio, camber, airfoil profile, types and sizes of leading edge/trailing edge flaps/flaperons, wing interactions with other aircraft structures (such as LERX and canards), thickness ratio, how it is integrated with the fuselage, etc.

In the end, I believe that the J-20 was designed with agility as a high priority. Not just the theoretical wing loading calculations, but the all-moving canards, tails and the canopy design lead me to this conclusion as well. If speed, supersonic cruise and range were all they cared about, a tailless delta would probably have been both a stealthier and a less-draggy option than a canard-delta.
« Last Edit: January 03, 2013, 11:11:30 pm by Kryptid »
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Offline latenlazy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #116 on: January 04, 2013, 02:46:36 am »
Way back when the first J-20 pics came out, I thought stealthy interceptor/light bomber/anti-ship with a little bit of fighter agility in there too but not much. Depending on how big the bomb bay volume is. It's at least as big as the f-22s. A stealthy Mig-31/F-111 with some added agility.


Mig-31 type Interceptor to supercruise patrol those vast Chinese borders, anti-ship/anti US carrier, and some light stealthy bombing missions. Actually, the Chinese would deem the f-22 as inadequate for those functions. they wanted more fuel volume and a bigger weapons bay and they got it. but obviously they like the canard heritage of the j-10 and the frontal stealth aspect of the f-22. Its going to be perfect for their needs.


The j-31 if it gets to production will fill their low-end needs and export. the Chinese are doing really good commercially, and their aerospace industry is pragmatic and cost effective. They might even outsell the f-35 because of affordabilty. We will see. Makes me wonder what their next Gen design is going to look like.


As far as stealth, i would even say the J-20 is Stealthier than the Sukhoi T-50.
No one sticks canards onto a plane just because they like it. The chines, LERXes, and canards all indicate a plane that's optimized for maneuverability, so I'm dubious of the conclusion that it will have limited agility.

knowing more or less the dimensions of j20, one can superimpose the pice of it and f22 taken from the front and then one can tell the frontal cross section is pretty similar to one of f22. however, fuselage length difference is noticeable. f22 has quite an overhang of its control surfaces behind the engine nozzles. j20 has less of an overhang. all in all, j20 has fuselage that is easely 2 meters longer. Plus a more tapered belly towards the engine nozzles.


I would be surprised if j20 doesn't end up having at least some 4-5 cubic meters of internal fuselage volume more than the f22. Weapons bay seems to be some 20% bigger, so part of the extra volume is spent there. Perhaps ws15 engines are planned to be of somewhat greater dimensions... or/and they use more fuel per thrust given. who's to say. but the plane certainly has plenty of room for fuel. that is, of course, both good and bad at the same time.
I wonder about that. While the J-20's fuselage does seem longer, the F-22's horizontal and vertical tails are much bigger than the J-20's vertical tails and canards. That should offset some of the volume difference.

Assuming the reference image I used to calculate wing area was fairly accurate, I arrived at these approximate figures for overall reference wing area based on the speculated dimensions provided above:

Length - Wing Area
19.2 meters (63 feet) - 71 square meters (763 square feet)
20.35 meters (66.75 feet) - 79.9 square meters (860 square feet)
20.7 meters (67.9 feet) - 82.6 square meters (889 square feet)

For comparison, the F-22 has a length of slightly above 18.9 meters (62 feet) and a wing area of 78.4 square meters (840 square feet).

If (and this is a big if) the J-20 has a similar weight per unit length as the F-22, the following wing loadings can be calculated. These figures may not be that unreasonable since the two are in roughly the same size range and have similar design elements (the boxy fuselage, closely-spaced engines, low aspect ratio wings, fixed inlets, internal weapons, same canopy, etc). Take note that I did some rounding with the numbers.

Length - Loaded Weight - Wing Loading

19.2 meters (63 feet) - 29,700 kilograms (65,400 pounds) - 418 kilograms/square meter (86 pounds/square foot)
20.35 meters (66.75 feet) - 31,500 kilograms (69,300 pounds) - 394 kilograms/square meter (81 pounds/square foot)
20.7 meters (67.9 feet) - 32,000 kilograms (70,500 pounds) - 387 kilograms/square meter (79 pounds/square foot)

You may have noticed that the larger values for length generate lower values for wing loading. Due to scaling laws, this is almost certainly incorrect. Using the square-cube law (and using the lowest length value as a baseline) more realistic wing loadings may be calculated:

Length - Loaded Weight - Wing Loading

19.2 meters (63 feet) - 29,700 kilograms (65,400 pounds) - 418 kilograms/square meter (86 pounds/square foot)
20.35 meters (66.75 feet) - 35,400 kilograms (77,900 pounds) - 443 kilograms/square meter (91 pounds/square foot)
20.7 meters (67.9 feet) - 37,200 kilograms (82,000 pounds) - 450 kilograms/square meter (92 pounds/square foot)

For comparison, the F-22's loaded weight is 29,300 kilograms (64,460 pounds) and its wing loading in this state is 375 kilograms/square meter (77 pounds/square foot). All of these estimates put it at a higher wing loading than the F-22. However, I would also like to point out the the range of wing loadings calculated is still rather "fighter-like". Compare these values with those of the F-16C Block 30 (at 431 kg/m2 or 88.3 lb/ft2), the F-35A (at 526 kg/m2 or 107 lb/ft2), the F/A-18E/F (at 459 kg/m2 94 lb/ft2), and the Su-35S (at 408 kg/m2 or 84.9 lb/ft2).

It should also be remembered that there are many other factors that affect an aircrafts lift than just wing loading alone. There is also leading edge sweep, taper ratio, camber, airfoil profile, types and sizes of leading edge/trailing edge flaps/flaperons, wing interactions with other aircraft structures (such as LERX and canards), thickness ratio, how it is integrated with the fuselage, etc.

In the end, I believe that the J-20 was designed with agility as a high priority. Not just the theoretical wing loading calculations, but the all-moving canards, tails and the canopy design lead me to this conclusion as well. If speed, supersonic cruise and range were all they cared about, a tailless delta would probably have been both a stealthier and a less-draggy option than a canard-delta.
How are you calculating the wing area? Are you just using the dimension of the wings, or are you including the fuselage area between the wings? If the former, are you doing the same with the F-22, or did you get pull that number from a reference? Regardless, good thorough work!

I think we've tried to calculate the wing area of the F-22 before just using the wing dimensions and got results that didn't match the reference.
« Last Edit: January 04, 2013, 02:59:10 am by latenlazy »

Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #117 on: January 04, 2013, 03:44:40 am »
I simply don't think the likely engine thrust and wing area suggests a versatile and maneuverable fighter capable of handling an exceptional internal fuel capacity.     

Do you think a Flanker is going to be flying Cobras etc. with a full internal fuel load?  (That's a rhetorical question, because of course it's not.)
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Offline siegecrossbow

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #118 on: January 04, 2013, 05:59:08 am »
Assuming the reference image I used to calculate wing area was fairly accurate, I arrived at these approximate figures for overall reference wing area based on the speculated dimensions provided above:

Length - Wing Area
19.2 meters (63 feet) - 71 square meters (763 square feet)
20.35 meters (66.75 feet) - 79.9 square meters (860 square feet)
20.7 meters (67.9 feet) - 82.6 square meters (889 square feet)

For comparison, the F-22 has a length of slightly above 18.9 meters (62 feet) and a wing area of 78.4 square meters (840 square feet).

If (and this is a big if) the J-20 has a similar weight per unit length as the F-22, the following wing loadings can be calculated. These figures may not be that unreasonable since the two are in roughly the same size range and have similar design elements (the boxy fuselage, closely-spaced engines, low aspect ratio wings, fixed inlets, internal weapons, same canopy, etc). Take note that I did some rounding with the numbers.

Length - Loaded Weight - Wing Loading

19.2 meters (63 feet) - 29,700 kilograms (65,400 pounds) - 418 kilograms/square meter (86 pounds/square foot)
20.35 meters (66.75 feet) - 31,500 kilograms (69,300 pounds) - 394 kilograms/square meter (81 pounds/square foot)
20.7 meters (67.9 feet) - 32,000 kilograms (70,500 pounds) - 387 kilograms/square meter (79 pounds/square foot)

You may have noticed that the larger values for length generate lower values for wing loading. Due to scaling laws, this is almost certainly incorrect. Using the square-cube law (and using the lowest length value as a baseline) more realistic wing loadings may be calculated:

Length - Loaded Weight - Wing Loading

19.2 meters (63 feet) - 29,700 kilograms (65,400 pounds) - 418 kilograms/square meter (86 pounds/square foot)
20.35 meters (66.75 feet) - 35,400 kilograms (77,900 pounds) - 443 kilograms/square meter (91 pounds/square foot)
20.7 meters (67.9 feet) - 37,200 kilograms (82,000 pounds) - 450 kilograms/square meter (92 pounds/square foot)

For comparison, the F-22's loaded weight is 29,300 kilograms (64,460 pounds) and its wing loading in this state is 375 kilograms/square meter (77 pounds/square foot). All of these estimates put it at a higher wing loading than the F-22. However, I would also like to point out the the range of wing loadings calculated is still rather "fighter-like". Compare these values with those of the F-16C Block 30 (at 431 kg/m2 or 88.3 lb/ft2), the F-35A (at 526 kg/m2 or 107 lb/ft2), the F/A-18E/F (at 459 kg/m2 94 lb/ft2), and the Su-35S (at 408 kg/m2 or 84.9 lb/ft2).

It should also be remembered that there are many other factors that affect an aircrafts lift than just wing loading alone. There is also leading edge sweep, taper ratio, camber, airfoil profile, types and sizes of leading edge/trailing edge flaps/flaperons, wing interactions with other aircraft structures (such as LERX and canards), thickness ratio, how it is integrated with the fuselage, etc.

In the end, I believe that the J-20 was designed with agility as a high priority. Not just the theoretical wing loading calculations, but the all-moving canards, tails and the canopy design lead me to this conclusion as well. If speed, supersonic cruise and range were all they cared about, a tailless delta would probably have been both a stealthier and a less-draggy option than a canard-delta.

This is a very interesting bit of analysis. If you don't mind I am porting it to sinodefence and see what the gents there think of it.

Thank you in advance.

Offline Sundog

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #119 on: January 04, 2013, 07:22:28 am »
The simple answer is that the J-20 is optimized for supercruise where as the F-22 isn't, as it's designed to supposedly do everything well. Unfortunately, the F-22s fuel fraction was marginal to begin with, you want a fuel fraction greater than .25 for a supercruise fighter, but due to weight increases the F-22 is now below that number. Providing the Chinese were able to control the weight of their aircraft well it should prove to be a very capable supercruise fighter if they can get engines up to the task..




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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #120 on: January 04, 2013, 08:18:40 am »
The simple answer is that the J-20 is optimized for supercruise where as the F-22 isn't, as it's designed to supposedly do everything well. Unfortunately, the F-22s fuel fraction was marginal to begin with, you want a fuel fraction greater than .25 for a supercruise fighter, but due to weight increases the F-22 is now below that number. Providing the Chinese were able to control the weight of their aircraft well it should prove to be a very capable supercruise fighter if they can get engines up to the task..

So the J-20 being optimized for supercruise means it can't manuever?  Wut?
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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #121 on: January 04, 2013, 08:49:59 am »
Quote
How are you calculating the wing area? Are you just using the dimension of the wings, or are you including the fuselage area between the wings? If the former, are you doing the same with the F-22, or did you get pull that number from a reference? Regardless, good thorough work!I think we've tried to calculate the wing area of the F-22 before just using the wing dimensions and got results that didn't match the reference.

I used the 3-view available on Wikipedia. Probably a fan-made drawing. If one assumes a given length, it's fairly straightforward to calculate reference wing area (which does include the "wing" covered by the fuselage) if one has a drawing available. The F-22 wing area was pulled from Wikipedia as well (not extracted from a drawing).
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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #122 on: February 18, 2013, 05:33:10 pm »
A closeup of the J-20 engine exhausts shows them to be AL-31 exhausts, as I insisted from the beginning.

I believe they are likely to be higher thrust AL-31F derivatives from Salyut.


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« Last Edit: February 18, 2013, 05:35:00 pm by PaulMM (Overscan) »
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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #123 on: February 18, 2013, 07:50:42 pm »
I think there isn't serious doubt that AF-31s are fitted on the prototype most of the time.  The only uncertainty was whether a different nozzle with LO serrated trailing edge, probably belonging to WS-10, was briefly fitted.

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #124 on: February 18, 2013, 08:26:26 pm »
So the J-20 being optimized for supercruise means it can't manuever?  Wut?

My comment didn't get into any investigation of the maneuverability of either aircraft, so I understand your confusion. My comment was strictly about supercruise ability, as clearly written in the comment itself.

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #125 on: February 19, 2013, 01:55:52 am »
A closeup of the J-20 engine exhausts shows them to be AL-31 exhausts, as I insisted from the beginning.

I believe they are likely to be higher thrust AL-31F derivatives from Salyut.

AL-31FM1 is definitely a possibility, AL-31FM2 will apparently not start flight tests until this year so I would suggest that's out as even for a technology demonstrator it wouldn't be mature enough. The other alternatives would be that its a custom job done by Salyut for the Chinese (possibly in return for further AL-31FN orders) or the Chinese diverted AL-31FNs from the J-10 programme and modified them for higher thrust- with reduced fuel efficiency and a shorter MTBO.

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #126 on: February 19, 2013, 09:48:11 am »
A closeup of the J-20 engine exhausts shows them to be AL-31 exhausts, as I insisted from the beginning.

I believe they are likely to be higher thrust AL-31F derivatives from Salyut.

AL-31FM1 is definitely a possibility, AL-31FM2 will apparently not start flight tests until this year so I would suggest that's out as even for a technology demonstrator it wouldn't be mature enough. The other alternatives would be that its a custom job done by Salyut for the Chinese (possibly in return for further AL-31FN orders) or the Chinese diverted AL-31FNs from the J-10 programme and modified them for higher thrust- with reduced fuel efficiency and a shorter MTBO.

I wonder why Russians do not use their engine leverage over the Chinese to force more concessions from the Chinese in the area of purchases of large number of complete aircrafts.   

Offline quellish

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #127 on: February 19, 2013, 07:00:19 pm »
As far as stealth, i would even say the J-20 is Stealthier than the Sukhoi T-50.

No, and they are designed for different threats. This is like saying the F-22 is stealthier than the B-2.

Offline Sundog

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #128 on: March 13, 2013, 03:49:37 pm »
I don't know if you guys already saw these. Some nice close up pictures at the link. Those of you at CDF probably have already.

http://news.xinhuanet.com/english/photo/2013-01/17/c_132108052.htm


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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #129 on: March 13, 2013, 10:50:26 pm »

I wonder what sort of actuator arrangement they used to facilitate plus minus 85 degree deflection on those canards, provided the canards can deflect as much up as down.   Also there are no big bulges or fairing above to accommodate a linear actuator and pivot sweep arms to provide moment arm for the actuators.  Must be some sort of rotary actuator.

Offline Sundog

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #130 on: March 14, 2013, 10:36:10 am »

I wonder what sort of actuator arrangement they used to facilitate plus minus 85 degree deflection on those canards, provided the canards can deflect as much up as down.   Also there are no big bulges or fairing above to accommodate a linear actuator and pivot sweep arms to provide moment arm for the actuators.  Must be some sort of rotary actuator.

The actuator could easily be positioned below the canard.

Offline Sundog

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #131 on: March 14, 2013, 10:39:17 am »
The "new" engine. Any ideas, as I haven't been following the powerplant choices too closely. Indeginous Chinese design, or Russian?
 
http://alert5.com/wp-content/uploads/2013/03/578415_10151478128839043_1735289026_n1.jpg

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #132 on: March 14, 2013, 11:58:29 am »

I wonder what sort of actuator arrangement they used to facilitate plus minus 85 degree deflection on those canards, provided the canards can deflect as much up as down.   Also there are no big bulges or fairing above to accommodate a linear actuator and pivot sweep arms to provide moment arm for the actuators.  Must be some sort of rotary actuator.

The actuator could easily be positioned below the canard.

Linear actuators would be very ineffecient if the canards can deflect up and down by 85 degrees around a pivot.   At extreme of deflection the moment arm of the linear actuators would be almost nothing, and they would be excerting their force in a direction almost orthogonal to the desired direction.

Offline latenlazy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #133 on: March 14, 2013, 09:18:39 pm »
The "new" engine. Any ideas, as I haven't been following the powerplant choices too closely. Indeginous Chinese design, or Russian?
 
http://alert5.com/wp-content/uploads/2013/03/578415_10151478128839043_1735289026_n1.jpg
Uh. No. That's still the old engines, AL-31.
« Last Edit: March 14, 2013, 09:22:24 pm by latenlazy »

Offline PaulMM (Overscan)

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #134 on: March 14, 2013, 11:17:38 pm »
Yep, still AL-31.
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Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #135 on: March 15, 2013, 12:55:01 am »
Is it possible to estimate the intended thrust of J-20's ultimate engine from the size of the intake on the prototype and thus the flow rate of the engine?  Admittedly the size of the intake could change during production, but they may not have customized the intake to a temporary engine, and the intake may represent the intended production size.
 

Offline latenlazy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #136 on: March 15, 2013, 02:59:38 am »
Is it possible to estimate the intended thrust of J-20's ultimate engine from the size of the intake on the prototype and thus the flow rate of the engine?  Admittedly the size of the intake could change during production, but they may not have customized the intake to a temporary engine, and the intake may represent the intended production size.
I don't think so. Too many other variables, like the temperature of the combustion chamber.

Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #137 on: March 15, 2013, 05:30:37 am »
Is it possible to estimate the intended thrust of J-20's ultimate engine from the size of the intake on the prototype and thus the flow rate of the engine?  Admittedly the size of the intake could change during production, but they may not have customized the intake to a temporary engine, and the intake may represent the intended production size.

And it's not always that clear-cut.  Take the F-14 and F-15.  One went from the 20k TF-30 to the 28k F110 with no intake change.  The other went from a 23k F100 to a 30k F100 also with no intake change.
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Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #138 on: March 15, 2013, 10:20:14 am »
Is it possible to estimate the intended thrust of J-20's ultimate engine from the size of the intake on the prototype and thus the flow rate of the engine?  Admittedly the size of the intake could change during production, but they may not have customized the intake to a temporary engine, and the intake may represent the intended production size.

And it's not always that clear-cut.  Take the F-14 and F-15.  One went from the 20k TF-30 to the 28k F110 with no intake change.  The other went from a 23k F100 to a 30k F100 also with no intake change.

F-14 and F-15's intakes were clearly overdesigned for their original engines to permit later upgrades.    But can one establish an upper limit to how much thrust any engine of a given state of technology, sucking through those intakes, and operating normally could possibly generate?   
 
If one could do that with F-14 and F-15, one ought to be able to do it more easily with the J-20 because:
 
1. J-20 probably has a fixed inlet because it is stealthy.   So inlet maximum massflow is probably easier to estimate.
 
2. If the J-20 is indeed optimized to supercruise, as its length suggests, whatever engine it uses ought to be closer to a pure turbojet than the F100 or F110.   As a result, there is less room for the engine thrust limit to be effected by the bypass ratio of the engine.   So there would be fewer variables that could upset maximum thrust estimates besides intake mass flow and turbine inlet temperature.
 
 
« Last Edit: March 15, 2013, 10:31:33 am by chuck4 »

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #139 on: March 15, 2013, 01:07:01 pm »
And it's not always that clear-cut.  Take the F-14 and F-15.  One went from the 20k TF-30 to the 28k F110 with no intake change.  The other went from a 23k F100 to a 30k F100 also with no intake change.
Both have variable intake geometry (capture area and bypass, respectively) which allows a measure of adaptation to a new engine with different airflow requirements without hardware changes, simply by matching the scheduling of aforementioned features appropriately. In the F-14's case, there's also the fact that the inlets were actually sized for an engine much closer to the eventual F110 than the (notionally interim) TF30s it got stuck with for so long.
A better example is probably the Eurofighter Typhoon, which went from a high bypass ratio interim engine (RB.199) in the early prototypes to a low bypass ratio power plant (though with considerably more thrust), despite fixed intakes.
« Last Edit: March 15, 2013, 01:11:25 pm by Trident »

Offline latenlazy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #140 on: March 16, 2013, 02:50:08 am »
Is it possible to estimate the intended thrust of J-20's ultimate engine from the size of the intake on the prototype and thus the flow rate of the engine?  Admittedly the size of the intake could change during production, but they may not have customized the intake to a temporary engine, and the intake may represent the intended production size.

And it's not always that clear-cut.  Take the F-14 and F-15.  One went from the 20k TF-30 to the 28k F110 with no intake change.  The other went from a 23k F100 to a 30k F100 also with no intake change.

F-14 and F-15's intakes were clearly overdesigned for their original engines to permit later upgrades.    But can one establish an upper limit to how much thrust any engine of a given state of technology, sucking through those intakes, and operating normally could possibly generate?   
 
If one could do that with F-14 and F-15, one ought to be able to do it more easily with the J-20 because:
 
1. J-20 probably has a fixed inlet because it is stealthy.   So inlet maximum massflow is probably easier to estimate.
 
2. If the J-20 is indeed optimized to supercruise, as its length suggests, whatever engine it uses ought to be closer to a pure turbojet than the F100 or F110.   As a result, there is less room for the engine thrust limit to be effected by the bypass ratio of the engine.   So there would be fewer variables that could upset maximum thrust estimates besides intake mass flow and turbine inlet temperature.
And what if the J-20 is using an internal bleed system for mass flow control like the F-22, or some other novel inlet control system?

And it's not always that clear-cut.  Take the F-14 and F-15.  One went from the 20k TF-30 to the 28k F110 with no intake change.  The other went from a 23k F100 to a 30k F100 also with no intake change.
Both have variable intake geometry (capture area and bypass, respectively) which allows a measure of adaptation to a new engine with different airflow requirements without hardware changes, simply by matching the scheduling of aforementioned features appropriately. In the F-14's case, there's also the fact that the inlets were actually sized for an engine much closer to the eventual F110 than the (notionally interim) TF30s it got stuck with for so long.
A better example is probably the Eurofighter Typhoon, which went from a high bypass ratio interim engine (RB.199) in the early prototypes to a low bypass ratio power plant (though with considerably more thrust), despite fixed intakes.
I thought the EF had variable intakes? The F-16 would be a good example.
« Last Edit: March 16, 2013, 02:52:46 am by latenlazy »

Offline Trident

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #141 on: March 16, 2013, 06:53:25 am »
I thought the EF had variable intakes? The F-16 would be a good example.


The Typhoon's intakes have moveable lips, but they aren't really supposed to change the capture area (resulting in a pronouced throat!) so much as act like airflow smoothing devices. Think of them as "LE flaps" for the inlet lip, to avoid flow separation at high AoA and/or low forward speed, when air may be arriving at an angle to the edge.
The F-16 is a poor example, as it did require the inlet to be enlarged to take full advantage of the F110 :)

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #142 on: March 16, 2013, 08:36:06 am »

And what if the J-20 is using an internal bleed system for mass flow control like the F-22, or some other novel inlet control system?
.


F-22's bleed system is manifest in the obvios serrated bleed doors on the upper fuselage surface.   Don't see anything similar on the j-20.    If j-20 use internal bleed, the air has to come out somewhere.

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #143 on: March 16, 2013, 08:41:26 am »
.
A better example is probably the Eurofighter Typhoon, which went from a high bypass ratio interim engine (RB.199) in the early prototypes to a low bypass ratio power plant (though with considerably more thrust), despite fixed intakes.


I think we can assume j-20 would also get a low bypass engine eventually for the same reason.   Fixed intake without visible flow control, low bypass engine of somewhere between f100 and f119 technology.   Is that enough to put a narrow confidence band on maximum thrust?

Offline Sundog

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #144 on: March 16, 2013, 01:09:58 pm »
F-22's bleed system is manifest in the obvios serrated bleed doors on the upper fuselage surface.   Don't see anything similar on the j-20.    If j-20 use internal bleed, the air has to come out somewhere.

The serrated doors on top center of the F-22 are not bleed doors. They are "suck in" doors, or extra inlets, since having fixed inlets, the engines need another way to get the mass flow they need when it's sitting on the ground, since you don't get the ram affect sitting still/without airspeed. Not all planes with fixed inlets have them. It's a function of the mass flow rate required by the engine and what the intakes have been optimized for, which is usually the cruise design point.

Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #145 on: March 16, 2013, 01:18:02 pm »
F-22's bleed system is manifest in the obvios serrated bleed doors on the upper fuselage surface.   Don't see anything similar on the j-20.    If j-20 use internal bleed, the air has to come out somewhere.

The serrated doors on top center of the F-22 are not bleed doors. They are "suck in" doors, or extra inlets, since having fixed inlets, the engines need another way to get the mass flow they need when it's sitting on the ground, since you don't get the ram affect sitting still/without airspeed. Not all planes with fixed inlets have them. It's a function of the mass flow rate required by the engine and what the intakes have been optimized for, which is usually the cruise design point.

They are bleed doors as well.  Look at which way they open.  They operate the same way as the doors on the XF8U-3 Crusader.  Just a different way of accomplishing the same thing a VG intake does.
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Offline latenlazy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #146 on: March 16, 2013, 05:29:50 pm »

And what if the J-20 is using an internal bleed system for mass flow control like the F-22, or some other novel inlet control system?
.


F-22's bleed system is manifest in the obvios serrated bleed doors on the upper fuselage surface.   Don't see anything similar on the j-20.    If j-20 use internal bleed, the air has to come out somewhere.
I thought the dorsal exhausts on the J-20 might be bleed doors, but they're probably too small for that purpose huh?

Offline Sundog

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #147 on: March 16, 2013, 05:33:52 pm »
They are bleed doors as well.  Look at which way they open.  They operate the same way as the doors on the XF8U-3 Crusader.  Just a different way of accomplishing the same thing a VG intake does.

I'll check it out. I would have thought the inlets on the F-22 would have been better matched, due to the amount of drag caused by dumping low energy air overboard. Thanks.

Offline Trident

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #148 on: March 16, 2013, 07:32:43 pm »
F-22's bleed system is manifest in the obvios serrated bleed doors on the upper fuselage surface.   Don't see anything similar on the j-20.    If j-20 use internal bleed, the air has to come out somewhere.

The serrated doors on top center of the F-22 are not bleed doors. They are "suck in" doors, or extra inlets, since having fixed inlets, the engines need another way to get the mass flow they need when it's sitting on the ground, since you don't get the ram affect sitting still/without airspeed. Not all planes with fixed inlets have them. It's a function of the mass flow rate required by the engine and what the intakes have been optimized for, which is usually the cruise design point.

They are bleed doors as well.  Look at which way they open.  They operate the same way as the doors on the XF8U-3 Crusader.  Just a different way of accomplishing the same thing a VG intake does.


 
They are bleed doors as well.  Look at which way they open.  They operate the same way as the doors on the XF8U-3 Crusader.  Just a different way of accomplishing the same thing a VG intake does.

I'll check it out. I would have thought the inlets on the F-22 would have been better matched, due to the amount of drag caused by dumping low energy air overboard. Thanks.
It's an interesting issue - as you say, you'd expect inlets as small as possible on an aircraft optimised for high speed cruise. Depending on what source you look at you'll find them labelled as one or the other, and even on photos it's not easy to tell - take this close up:
http://www.af.mil/shared/media/photodb/photos/080608-F-0154C-104.jpg
They look as though they'd open the way auxiliary inlet doors would, judging by how the edges overlap. Then again:
http://cdn-www.airliners.net/aviation-photos/photos/9/4/6/1790649.jpg

Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #149 on: March 16, 2013, 09:21:54 pm »
They look as though they'd open the way auxiliary inlet doors would, judging by how the edges overlap. Then again:
http://cdn-www.airliners.net/aviation-photos/photos/9/4/6/1790649.jpg
I'd wager in that shot they're just open as part of the control surface test routine.  Notice the horizontal stab and TVC are angled down and the rudders are toed out. 
« Last Edit: March 16, 2013, 09:23:51 pm by sferrin »
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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #150 on: March 16, 2013, 11:04:42 pm »
I am not sure how louvre flaps that seem to be hinged at the front and swings outwards at the rear could appear to be suck in doors.   It seems to me this arrangement is intended to operate with airflow coming from lower front through the flaps exiting upper rear, ie from inside of the plane up and back out of the plane.


Suck in doors would operate the other way, hinged at the front and swings inwards, such as those on av-8b's dumbo ear intakes.    This way they operates best with airflow coming from upper front in through the door towards lower rear.


You can see the doors on f-22 only swings outwards because the trailing serrated edge of each flap overlaps the hinge of the flap behind it.



« Last Edit: March 16, 2013, 11:06:49 pm by chuck4 »

Offline Trident

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #151 on: March 17, 2013, 06:36:00 am »
They look as though they'd open the way auxiliary inlet doors would, judging by how the edges overlap. Then again:
http://cdn-www.airliners.net/aviation-photos/photos/9/4/6/1790649.jpg
I'd wager in that shot they're just open as part of the control surface test routine.  Notice the horizontal stab and TVC are angled down and the rudders are toed out.


Yes, that's what I meant: they appear to be power-operated bleed doors as opposed to spring-loaded suck-in doors - they open the wrong way to be the latter, at least on this picture.

Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #152 on: March 17, 2013, 08:28:20 am »
Yes, that's what I meant: they appear to be power-operated bleed doors as opposed to spring-loaded suck-in doors - they open the wrong way to be the latter, at least on this picture.


They are definitely powered.  Flateric used to have a video of them in operation on his Youtube channel.
 
Here it is:
&[/quote]
« Last Edit: March 17, 2013, 08:57:49 am by sferrin »
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Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #153 on: March 17, 2013, 08:43:06 am »
So f-22 has internal bleed that exits through dorsal bleed doors.  J -20 probably doesn't as there areno visible doors.   That ought to mean j-20's maximum thrust is more tightly constrained by inlet dimension than f-22.   No?

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #154 on: March 17, 2013, 09:50:44 am »
Yes, that's what I meant: they appear to be power-operated bleed doors as opposed to spring-loaded suck-in doors - they open the wrong way to be the latter, at least on this picture.


They are definitely powered.  Flateric used to have a video of them in operation on his Youtube channel.
 
Here it is:


Interesting, thanks for pointing that one out (& to Flateric for sharing it)![/quote]

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #155 on: March 18, 2013, 03:10:23 pm »
An interesting info was posted today at the SDF regarding the J-20's flight requirements and esp. a comparison to its competitor from Shenyang (posted by "Engineer"):

Quote
This is written by one of SAC's engineers, which talked about their tri-surface design that competed with J-20.  The most important piece of knowledge in the text is that PLAAF gave a requirement that China's forth-generation must be able to fly in 60° AoA.  From this, we can see the capability of J-20.
 
 CAC's proposal uses canard configuration right from the beginning, but SAC's original proposal was a traditional layout with LERX.  The traditional layout was found to be uncontrollable between 40° ~ 45° AoA and didn't meet the requirement.  So, SAC modified the design to include canards, resulting in a tri-surface layout that remained controllable up to 65° AoA.  So once again, a configuration with canard proved to be superior to a traditional layout.


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Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #156 on: March 20, 2013, 07:23:28 am »
New video



with some discussion if at 4:26 the side door is open or not. However it seems as if there's something looking out of the fuselage and if I would not know better I would say it could be a launch rail of an AAM from the side bay !??
 
 Deino
« Last Edit: March 20, 2013, 07:29:41 am by Deino »
He was my North, my South, my East and West,
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Offline JFC Fuller

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #157 on: March 20, 2013, 07:46:56 am »
Having watched the video, 4.26 to 4.32 being the pertinent section, it certainly looks very much like there is a missile launch rail protruding from the starboard side weapons bay. 

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #158 on: March 20, 2013, 07:55:40 am »
Agreed ... but I'm surprised why this rail is shown during landing ? ... since right after landing the bay is closed again.

Deino  ???
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Offline Grey Havoc

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #159 on: March 20, 2013, 07:59:19 am »
Some sort of drag test?
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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #160 on: March 20, 2013, 08:00:36 am »
I don't think it is a missile rail because i can't see any separate openned missile bay door, which has to be there for the rail to show.   I think more likely it is actually just the lower half of an openned missile door.
« Last Edit: March 20, 2013, 08:03:44 am by chuck4 »

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #161 on: March 20, 2013, 08:19:19 am »
I think You are correct ... if You slow down the video image by image it seems as if the door is closing just before landing and what looks like attachments of the rail are a gap between fuselage and closing door.

Then the question howeber would by WHY ?? was there a malfunction and the doors only closing so late or was it again to initiate additional discussions at the forums since flight testing beacme almost boring in recent times ?  ;)

Deino
He was my North, my South, my East and West,
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For nothing now can ever come to any good.
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Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #162 on: March 20, 2013, 09:35:33 am »
Now I'm no longer sure ... seems indeed like a rail !
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
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Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #163 on: March 20, 2013, 09:36:02 am »
Maybe the pilot fat fingered his touchscreen?

Offline Geoff_B

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #164 on: March 20, 2013, 10:35:36 am »
Looks like its bolted on to the fuselage below the side bay, could they be using it to intergrate missiles with the on-board systems possibly for targeting before they test them in weapon bays ?

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #165 on: March 20, 2013, 10:39:17 am »
Now I'm no longer sure ... seems indeed like a rail !

But where is the door?   The rails can not be exposed without the door being open.    I think it is just the door seen at an angle that reduced its profile and made it look like a rail.
 
 
 

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #166 on: March 20, 2013, 10:45:53 am »
Looks like its bolted on to the fuselage below the side bay, could they be using it to intergrate missiles with the on-board systems possibly for targeting before they test them in weapon bays ?

It's not seen on the jet after it landed.   So it can't be bolt on.  Must be something that either folds into the plane or retracts into the plane.
 
Also, it seems a bit early in the development cycle to worry about weapons integration, if you ask me.   
 

Offline Sundog

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #167 on: March 20, 2013, 11:10:56 am »
It could be a pod attached to the rail for loads/accoustic measurements with regards to the weapons bay, so they know what the "environment" will be for the weapons when tested.

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #168 on: March 21, 2013, 02:09:15 am »
There's currently an interesting theory going on some discussion if the missile could possibly be launched with the doors closed:

http://lt.cjdby.net/thread-1568080-1-1.html

If true indeed an interesting theory ... something like that attached below !

Deino
« Last Edit: March 21, 2013, 02:32:19 am by Deino »
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline 2IDSGT

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #169 on: March 21, 2013, 02:23:12 am »
There's currently an interesting theory going on some discussion if the missile could possibly be launched with the doors closed:

http://lt.cjdby.net/thread-1568080-1-1.html

If true indeed an interesting theory ... something like that attached below !

Deino

That's pretty cool, but might it reflect a limitation of some kind in their missiles/launch-systems?
« Last Edit: March 21, 2013, 02:32:52 am by Deino »

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #170 on: March 21, 2013, 02:31:07 am »
Here's a new image which seems to confirm this theory ... attached are the original (huge one) + two smaller ones I tried a bit to modify !  ???

Deino

He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline latenlazy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #171 on: March 21, 2013, 03:30:10 am »
There's currently an interesting theory going on some discussion if the missile could possibly be launched with the doors closed:

http://lt.cjdby.net/thread-1568080-1-1.html

If true indeed an interesting theory ... something like that attached below !

Deino

That's pretty cool, but might it reflect a limitation of some kind in their missiles/launch-systems?

I can't imagine what kind of launch system limitation would such a solution would address...It seems to be meant to maintain RCS during launch...

Offline 2IDSGT

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #172 on: March 21, 2013, 03:43:04 am »
There's currently an interesting theory going on some discussion if the missile could possibly be launched with the doors closed:

http://lt.cjdby.net/thread-1568080-1-1.html

If true indeed an interesting theory ... something like that attached below !

Deino

That's pretty cool, but might it reflect a limitation of some kind in their missiles/launch-systems?

I can't imagine what kind of launch system limitation would such a solution would address...It seems to be meant to maintain RCS during launch...
...Which begs the question: why do their missiles need to hang on the outside prior to launch and for how long?  Of course, the old Sidewinders on the F-22 need to hang out; but should things come that point, VLO wouldn't be much of a concern.
« Last Edit: March 21, 2013, 03:46:44 am by 2IDSGT »

Offline latenlazy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #173 on: March 21, 2013, 04:07:14 am »
There's currently an interesting theory going on some discussion if the missile could possibly be launched with the doors closed:

http://lt.cjdby.net/thread-1568080-1-1.html

If true indeed an interesting theory ... something like that attached below !

Deino

That's pretty cool, but might it reflect a limitation of some kind in their missiles/launch-systems?

I can't imagine what kind of launch system limitation would such a solution would address...It seems to be meant to maintain RCS during launch...
...Which begs the question: why do their missiles need to hang on the outside prior to launch and for how long?  Of course, the old Sidewinders on the F-22 need to hang out; but should things come that point, VLO wouldn't be much of a concern.
*Shrug* Maybe it's not meant to address any problems. Maybe it's just a better solution? For example, in a mission where VLO isn't as important they can probably use those hardpoints to mount weapons that don't fit in the bay. Or perhaps at BVR closing the bay doors minimizes the chance that you'd be detected, thereby maximizing your ability to hit a target without giving it a heads up?
« Last Edit: March 21, 2013, 04:09:16 am by latenlazy »

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #174 on: March 21, 2013, 06:51:29 am »
Still seems more likely to me that what we are seeing is the missile bay door itself, not a launch rail.




Offline JFC Fuller

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #175 on: March 21, 2013, 07:05:12 am »
A very interesting theory, I said it earlier and I will say it again, in the video it really looks like a launch rail, far more than it does the door.

Offline LowObservable

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #176 on: March 21, 2013, 07:50:38 am »
It might give you a more benign aero environment for launch. Or limit any aero effects from the open door, or aero loads on the door, hinges and actuators, to a transient. Or not expose the open door to blast. In short a lot of potential reasons for doing it that way.

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #177 on: March 21, 2013, 03:47:35 pm »
It might give you a more benign aero environment for launch. Or limit any aero effects from the open door, or aero loads on the door, hinges and actuators, to a transient. Or not expose the open door to blast. In short a lot of potential reasons for doing it that way.

If this is true, then it implies the launch arrangement is designed to hold the missile in the airstream for a certain amount if time.  This in turn implies the j-20 wasn't designed with lock-on after launch missile in mind.

Offline latenlazy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #178 on: March 21, 2013, 04:15:05 pm »
It might give you a more benign aero environment for launch. Or limit any aero effects from the open door, or aero loads on the door, hinges and actuators, to a transient. Or not expose the open door to blast. In short a lot of potential reasons for doing it that way.

If this is true, then it implies the launch arrangement is designed to hold the missile in the airstream for a certain amount if time.  This in turn implies the j-20 wasn't designed with lock-on after launch missile in mind.
Not mutually exclusive. It gives the J-20 the option to keep the missile in the airstream. I'm doubtful that the J-20 doesn't have lock on after fire capability, since that's needed for weapons fired from the belly bays.

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #179 on: March 21, 2013, 04:29:30 pm »
I am talking about ir missiles from side bays.   The ability to close the missile bay doors with missile held in the airstream does not exclude lock-on after launch IR missiles, but is redundant if the missiles can be simply ejected into the airstream and then be commanded by data link to acquire their Lock-on during free flight.

Offline latenlazy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #180 on: March 21, 2013, 04:40:54 pm »
I am talking about ir missiles from side bays.   The ability to close the missile bay doors with missile held in the airstream does not exclude lock-on after launch IR missiles, but is redundant if the missiles can be simply ejected into the airstream and then be commanded by data link to acquire their Lock-on during free flight.
Still not sure we can conclude that. It would imply the J-20 couldn't launch missiles with IR seekers from its belly bays, and I'm somewhat doubtful such a limitation would be acceptable for the main weapons bay.

Offline Blitzo

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #181 on: March 21, 2013, 04:48:20 pm »
I am talking about ir missiles from side bays.   The ability to close the missile bay doors with missile held in the airstream does not exclude lock-on after launch IR missiles, but is redundant if the missiles can be simply ejected into the airstream and then be commanded by data link to acquire their Lock-on during free flight.


My hypothesis is that the launch mechanism will keep the bay door open in the airstream a shorter overall time compared to F-22's mechanism. It will be beneficial for drag and leave another extra reflection surface exposed for a shorter amount of time.


This is assuming J-20 and F-22 have similar overall launch times for their side bays of course.


Also, F-22 side bays do not simply eject sidewinders like you described either, I believe. It too "holds" the missile on a rail for a brief moment until the motor ignites. J-20 I imagine works the same, but allows the door to close for the few milliseconds between lowering the rail out and missile launch.
« Last Edit: March 21, 2013, 04:51:32 pm by Blitzo »

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #182 on: March 21, 2013, 05:33:12 pm »
I am talking about ir missiles from side bays.   The ability to close the missile bay doors with missile held in the airstream does not exclude lock-on after launch IR missiles, but is redundant if the missiles can be simply ejected into the airstream and then be commanded by data link to acquire their Lock-on during free flight.


My hypothesis is that the launch mechanism will keep the bay door open in the airstream a shorter overall time compared to F-22's mechanism. It will be beneficial for drag and leave another extra reflection surface exposed for a shorter amount of time.


This is assuming J-20 and F-22 have similar overall launch times for their side bays of course.


Also, F-22 side bays do not simply eject sidewinders like you described either, I believe. It too "holds" the missile on a rail for a brief moment until the motor ignites. J-20 I imagine works the same, but allows the door to close for the few milliseconds between lowering the rail out and missile launch.


Aim-9X is based on missile bodies of older aim-9 version that isn't cleared to be ejected rather than rail launched.


 However, that is not the point.  The point is is if the missile can lock on after launch, then it won't need to remain attached to the aircraft and exposed to the airstream for any significant amount of time whether it is ejected or rail launched.   In this case The missile can go off the rails the moment it is extended into the airstream.   it seems hardly worth while to close the missile bay doors first before sending the missile on it's way.     In fact, having to open and close the door twice during each launch would only lengthen the launch cycle and extend the period of vulnerability.


However, if the missile must take time to lock on while attached to the aircraft, then it makes more sense to extend the rails, close the door to improve the aerodynamics and stealth characteristics while waiting for the  missile to seeks and locks on, and then open the doors and retract the rails after the missile leaves the rail.


Offline latenlazy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #183 on: March 21, 2013, 05:51:37 pm »
I am talking about ir missiles from side bays.   The ability to close the missile bay doors with missile held in the airstream does not exclude lock-on after launch IR missiles, but is redundant if the missiles can be simply ejected into the airstream and then be commanded by data link to acquire their Lock-on during free flight.


My hypothesis is that the launch mechanism will keep the bay door open in the airstream a shorter overall time compared to F-22's mechanism. It will be beneficial for drag and leave another extra reflection surface exposed for a shorter amount of time.


This is assuming J-20 and F-22 have similar overall launch times for their side bays of course.


Also, F-22 side bays do not simply eject sidewinders like you described either, I believe. It too "holds" the missile on a rail for a brief moment until the motor ignites. J-20 I imagine works the same, but allows the door to close for the few milliseconds between lowering the rail out and missile launch.


Aim-9X is based on missile bodies of older aim-9 version that isn't cleared to be ejected rather than rail launched.


 However, that is not the point.  The point is is if the missile can lock on after launch, then it won't need to remain attached to the aircraft and exposed to the airstream for any significant amount of time whether it is ejected or rail launched.   In this case The missile can go off the rails the moment it is extended into the airstream.   it seems hardly worth while to close the missile bay doors first before sending the missile on it's way.     In fact, having to open and close the door twice during each launch would only lengthen the launch cycle and extend the period of vulnerability.


However, if the missile must take time to lock on while attached to the aircraft, then it makes more sense to extend the rails, close the door to improve the aerodynamics and stealth characteristics while waiting for the  missile to seeks and locks on, and then open the doors and retract the rails after the missile leaves the rail.
I get that point, but it doesn't square too well with missiles that are stored in the main weapons bay. If the missile needs to seek and lock on its own then how do they fire from the mwb?

I have another hypothesis. What if the side bays can fit a mraam, but it can't clear safely from the fuselage when fired from the bay? Such a solution would make the side bays more versatile.

Offline Blitzo

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #184 on: March 21, 2013, 06:06:20 pm »
I get that point, but it doesn't square too well with missiles that are stored in the main weapons bay. If the missile needs to seek and lock on its own then how do they fire from the mwb?


maybe IR AAMs will not be fired from the belly weapons bay?

Quote
I have another hypothesis. What if the side bays can fit a mraam, but it can't clear safely from the fuselage when fired from the bay? Such a solution would make the side bays more versatile.

I sincerely doubt the side bays will be able to fit an mraam.


I am talking about ir missiles from side bays.   The ability to close the missile bay doors with missile held in the airstream does not exclude lock-on after launch IR missiles, but is redundant if the missiles can be simply ejected into the airstream and then be commanded by data link to acquire their Lock-on during free flight.


My hypothesis is that the launch mechanism will keep the bay door open in the airstream a shorter overall time compared to F-22's mechanism. It will be beneficial for drag and leave another extra reflection surface exposed for a shorter amount of time.


This is assuming J-20 and F-22 have similar overall launch times for their side bays of course.


Also, F-22 side bays do not simply eject sidewinders like you described either, I believe. It too "holds" the missile on a rail for a brief moment until the motor ignites. J-20 I imagine works the same, but allows the door to close for the few milliseconds between lowering the rail out and missile launch.


Aim-9X is based on missile bodies of older aim-9 version that isn't cleared to be ejected rather than rail launched.

What if the new SRAAM is developed to be rail launched rather than ejected? That would explain everything quite handily.


Quote
However, that is not the point.  The point is is if the missile can lock on after launch, then it won't need to remain attached to the aircraft and exposed to the airstream for any significant amount of time whether it is ejected or rail launched.   In this case The missile can go off the rails the moment it is extended into the airstream.   it seems hardly worth while to close the missile bay doors first before sending the missile on it's way.     In fact, having to open and close the door twice during each launch would only lengthen the launch cycle and extend the period of vulnerability.

That really depends on how fast they can make the doors open and close, I think.
Does opening and closing the door twice during the launch cycle lengthen the overall launch time, or was the door speed dependent on a set launch time they were required to achieve?



Quote
However, if the missile must take time to lock on while attached to the aircraft, then it makes more sense to extend the rails, close the door to improve the aerodynamics and stealth characteristics while waiting for the  missile to seeks and locks on, and then open the doors and retract the rails after the missile leaves the rail.

That is definitely one possible answer, but let's give benefit of the doubt that PL-10 has LOAL ability as rumours of the years have suggested. For the purposes of discussion, what else could justify this unique mechanism?
The only benefits I'd see, would be the reduced drag and door reflections of leaving them open for the entire launch cycle, assuming:
-overall launch time of J-20 is comparable to F-22 (i.e.: door opening and closing is very, very fast, but considering the side bay door seems to only open some 45 degrees relative to the side fuselage this may be possible)
-missile is LOAL



Btw, have there been any existing aircraft with dedicated SRAAM side bays that "eject" the missile out? Two problems with that come to mind, one, ejecting the missile from a side bay may launch it into any aircraft flying level with you (for belly weapon bays it's less of a problem, as flying in formation or with a wingman means your allies won't be beneath you). Two, would the aggressive maneuvering you'd expect in a WVR combat situation necessitate rail launch in any way?
« Last Edit: March 21, 2013, 06:09:43 pm by Blitzo »

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #185 on: March 21, 2013, 06:46:49 pm »
An alternative explanation may be the Chinese wanted the flexibility to lock the missile on either before or after launch, depending on the tactical situation.     I imagine in very close quarter combat, it may be advantageous to lock on the missile before it departs the rail.


I think we should reserve judgement until a better photo of the side bay on the j-20 appears.

Offline latenlazy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #186 on: March 21, 2013, 07:27:04 pm »

maybe IR AAMs will not be fired from the belly weapons bay?
Maybe, but I have doubts about that given what we know about China's intended datalink capabilities. What's so different about post release lock on for an IR missile vs a radar guided one? The inability to lock on after fire from the side bays implies the inability to lock on after fire, period.
Quote
I sincerely doubt the side bays will be able to fit an mraam.
You're probably right. Just checked my rough estimates and the numbers don't fly.
« Last Edit: March 21, 2013, 07:39:13 pm by latenlazy »

Offline PaulMM (Overscan)

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #187 on: March 21, 2013, 07:33:35 pm »
Maybe they want to be able to fire PL-8s from the sidebays, they have a few kicking about, and PL-10s only could also go in the main bay if wanted.
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Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #188 on: March 21, 2013, 10:29:27 pm »

maybe IR AAMs will not be fired from the belly weapons bay?
Maybe, but I have doubts about that given what we know about China's intended datalink capabilities. What's so different about post release lock on for an IR missile vs a radar guided one? The inability to lock on after fire from the side bays implies the inability to lock on after fire, period.



The technical challenge is more complicated then you think.

 The missile can't just lock onto the first target it sees.   It must not only communicate with the launching plane with datalink, it must also have a sufficiently accurate inertial navigation system onboard the missile so as to preserve the orientation of the reference frame of the launching aircraft so when launch aircraft gives a target direction to lock to, the missile, through high g maneuvers, would still keep track of what that direction ought to be in common terms with the airplane.   It muust also calculate the displacement with respect to the lunching aircraft, so that when it receive lock on instructions from the launching aircraft, the missile's seeker can correct for parallex amd point to the same target as stated in the instruction.   It has to do this in a package that fits inside a 5 inch tube and survive many Gs and severe vibration and temperature environments.





« Last Edit: March 21, 2013, 11:10:28 pm by chuck4 »

Offline latenlazy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #189 on: March 21, 2013, 11:03:39 pm »

maybe IR AAMs will not be fired from the belly weapons bay?
Maybe, but I have doubts about that given what we know about China's intended datalink capabilities. What's so different about post release lock on for an IR missile vs a radar guided one? The inability to lock on after fire from the side bays implies the inability to lock on after fire, period.



It's more complicated then you think.

 The missile can't just lock onto the first target it sees.   It must not only communicate with the launching plane with datalink, it must also have a sufficiently accurate inertial navigation system onboard the missile so as to preserve the orientation of the reference frame of the launching aircraft, and calculate the displacement with respect to the lunching aircraft, so that when it receive lock on instructions from the launching aircraft, the missile's seeker will point to the same target as stated in the instruction.


In a dog fight, where targets and friendlies can to intermingled, and both friendlies and targets can make large angular movements with respect to the radial coordinate system centered around eith the missile or the launching aircraft in very short time.   The challenges to a IR LOAL missile will be much greater those facing a LOAL medium range missile like the AMRAAM.
So you're suggesting that there's a limitation in communicating the inertial data from the launching aircraft to the missile, or a limitation in the missile's ability to figure out its own inertial frame of reference relative to the plane? I somehow find that hard to believe. Even if the problem exists now, I can't imagine it persisting throughout the lifetime of the J-20's service life.

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #190 on: March 21, 2013, 11:15:33 pm »
Yes, I think the problem of accurately retaining a inertial reference frame through high g maneuvers in a package that fits inside a 5 inch tube is not trivial.  It has clearly been solved because LOAL short range IR missiles exist.   But the Chinese may not be sufficiently close to state of the art in technologies critical for this purpose to garranty the j-20 won't have to use LOBL IR missiles for some time aft the Le enters service.


Also, the design of j-20 has to consider what weapon will be available when the plane enters service, not just what will become available before j-20 leaves service, in perhaps 50 years.

Offline latenlazy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #191 on: March 21, 2013, 11:39:58 pm »
Yes, I think the problem of accurately retaining a inertial reference frame through high g maneuvers in a package that fits inside a 5 inch tube is not trivial.  It has clearly been solved because LOAL short range IR missiles exist.   But the Chinese may not be sufficiently close to state of the art in technologies critical for this purpose to garranty the j-20 won't have to use LOBL IR missiles for some time aft the Le enters service.


Also, the design of j-20 has to consider what weapon will be available when the plane enters service, not just what will become available before j-20 leaves service, in perhaps 50 years.
Oh, I'm sure it's not trivial. I'm just not sure that China would be so behind. I'm not going to play the China copies everything card, but they have acquired a lot of knowledge about missiles by reverse engineering the ones they've bought. It's not like the the capabilities you're speaking about are new either. The US figured them out early enough, and I can't imagine the solution to the problem being that different from eject and fire SRAAMs that have been around for a while.

China isn't THAT behind in its electronics capabilities either. If they're not there yet a combination of espionage, and growing engineering capabilities will probably get them there soon enough. The J-20 will have to account for the weapons available upon entering service, but that isn't sometime in the near future either. Accelerated timeline or not, the J-20's induction is still years away.
« Last Edit: March 21, 2013, 11:49:48 pm by latenlazy »

Offline PaulMM (Overscan)

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #192 on: March 22, 2013, 12:08:40 am »
More photos and guesswork...

[attachment deleted by admin]
« Last Edit: March 22, 2013, 12:58:56 am by PaulMM (Overscan) »
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Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #193 on: March 22, 2013, 01:29:55 am »
A new nearly front view !
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
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W.H.Auden (1945)

Offline PaulMM (Overscan)

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #194 on: March 22, 2013, 01:51:05 am »
Better, I think.
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Offline Mat Parry

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #195 on: March 22, 2013, 02:14:17 am »
Regarding the "China copies everything card" taken at face value this innovation would seem to show otherwise (unless this idea was lifted from elsewhere and we just haven't seen it disclosed before). I'm not optimistic but I'll do a patent search and post if anything pops out.
Assuming this is one of the first examples of China inventing in an aviation context, I would expect other nations would have similar "intel gathering capabilities" ;) as China, so no doubt one of the Western alphabet agencies is well aware of the thinking behind this set up.

Offline PaulMM (Overscan)

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #196 on: March 22, 2013, 02:38:30 am »
Here's my rather crude sketch of how I think it works.
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Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #197 on: March 22, 2013, 05:14:11 am »
Regarding the "China copies everything card" taken at face value this innovation would seem to show otherwise (unless this idea was lifted from elsewhere and we just haven't seen it disclosed before). I'm not optimistic but I'll do a patent search and post if anything pops out.
Assuming this is one of the first examples of China inventing in an aviation context, I would expect other nations would have similar "intel gathering capabilities" ;) as China, so no doubt one of the Western alphabet agencies is well aware of the thinking behind this set up.


There is nothing wrong with copying.   If the backward country try to reinvent each wheel, it will either take an inordinately long time to, or never, catch up.  We are just alarmed that they are catching up so fast, so we disingenuously belittle their sound strategy to feel better.   

Offline Mat Parry

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #198 on: March 22, 2013, 07:21:00 am »
Yep fully agree, it's not just China, Even between major corperations in the west "Competitive Intelligence" is a highly valued tool. Of course nowadays the sources of competitor information is only ever openly published material....  :) ;D ;)  For example from published patents, the context of the patents and the names of the inventors you can map out discrete groups within an organisation and their main research interests, it's actually quite fun to do this for aerospace companies and you do find some surprising themes.
 
 

Offline Sundog

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #199 on: March 22, 2013, 10:39:01 am »
The problem with copying is that most of the advanced tech is being developed in the U.S., therefore American taxpayers are paying for it. None of those countries develops near as much as the U.S., so the U.S. loses a hell of a lot more than it gains as a result. Then again, we did train many of their Aero-engineers, so this is what we get for doing that.

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #200 on: March 22, 2013, 11:02:35 am »
I fear this may only be the start of our copying opportunities

Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #201 on: March 22, 2013, 11:40:12 am »
We don't even know what we're looking at and we're already talking about the decline of Western civilization.  How 'bout we wait for a better look?
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Offline Trident

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #202 on: March 22, 2013, 01:13:14 pm »
Wouldn't the door restrict the range of movement of the canard, especially when open far enough to clear a ready-to-fire missile? That would certainly be a good reason to keep the time during which the door is open to the absolute minimum!

Offline latenlazy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #203 on: March 22, 2013, 01:30:15 pm »
Wouldn't the door restrict the range of movement of the canard, especially when open far enough to clear a ready-to-fire missile? That would certainly be a good reason to keep the time during which the door is open to the absolute minimum!
On the other hand, the door would only need to lift high enough to let the rail clear it.

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #204 on: March 23, 2013, 08:32:50 am »
A new simulation ...
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
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Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #205 on: March 23, 2013, 09:17:53 am »
A new simulation ...

I guess the question I would ask would be "Why?" 
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Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #206 on: March 23, 2013, 09:25:12 am »
Why ??? why I posted this new simulation (simply since I found it and it illustrates a possible explanation) or why that strange mechanism ? (IMO to close the door with some benefits on stealth, exhaust in the weapons bay - problems - ...)


He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
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W.H.Auden (1945)

Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #207 on: March 23, 2013, 09:35:44 am »
Why ??? why I posted this new simulation (simply since I found it and it illustrates a possible explanation) or why that strange mechanism ? (IMO to close the door with some benefits on stealth, exhaust in the weapons bay - problems - ...)

Why the strange mechanism.  Doesn't seem like it'd be worth it.
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Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #208 on: March 23, 2013, 09:38:11 am »
New video





That video should put to rest the notion floating around a few days ago that it was flying with a new engine.
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Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #209 on: March 23, 2013, 10:48:40 am »
What new engine? looks like the same engine it has since 2009.

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #210 on: March 23, 2013, 12:50:08 pm »
Yes, ... but one of the engines was replaced with the silver coating missing and after one image was leaked with one of the engines showing the AB closed and the other one fully open some were asuming a new indigenous engine was installed.

Deino
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline hagaricus

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #211 on: March 24, 2013, 01:29:26 pm »
Is it just me, or is it landing with its weapons bay door partly open in that video?


Offline Sundog

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #212 on: March 24, 2013, 03:35:16 pm »
Is it just me, or is it landing with its weapons bay door partly open in that video?

As shown up-thread, that's the lunch-rail not the doors. The launch rail can stay extended when the doors are closed. Read up thread and look at the diagrams provided to see how they are going about that.

Offline hagaricus

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #213 on: March 24, 2013, 07:28:28 pm »
Is it just me, or is it landing with its weapons bay door partly open in that video?

As shown up-thread, that's the lunch-rail not the doors. The launch rail can stay extended when the doors are closed. Read up thread and look at the diagrams provided to see how they are going about that.

D'oh,  got it now...

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #214 on: March 26, 2013, 03:03:49 am »
Finally  ;)
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
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W.H.Auden (1945)

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #215 on: March 26, 2013, 05:11:52 am »
 ;) ;) ;)

http://www.iissbbs.com/viewthread.php?tid=4057829&extra=page%3D1

... and what's that on that pylon (1:27 - ... ) ????

Deino

PS: I'm not sure about that AAM but at CDF they say it's real.
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #216 on: March 26, 2013, 05:24:34 am »
Finally  ;)

It's definitely a more efficient use of space than the current F-22 side bays.  On the other hand, with a little work, I'll bet they could get two AIM-9Xs in each of the F-22s side bays.
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Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #217 on: March 26, 2013, 05:29:16 am »
... still not sure but at the CDF they take this as a confirmation for the PL-10 !
He was my North, my South, my East and West,
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My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
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Offline Geoff_B

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #218 on: March 26, 2013, 05:50:51 am »
Err Deino

What can we see in white on the inside of the belly weapons bay door ?



Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #219 on: March 26, 2013, 06:27:53 am »
Even if not fully confirmed it seems that this is the PL-10 IR-guided SR-AAM.
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline flateric

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #220 on: March 26, 2013, 08:14:10 am »
Err Deino

What can we see in white on the inside of the belly weapons bay door ?



Just an edge of second section of the weapon bay door.
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Offline PaulMM (Overscan)

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #221 on: March 26, 2013, 10:12:51 am »
Interesting comparison to the Ukrainian Gran' AAM and the K-30 AAM:








Could be photoshopped though.
« Last Edit: March 26, 2013, 10:16:12 am by PaulMM (Overscan) »
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Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #222 on: March 26, 2013, 10:21:19 am »
Interesting comparison to the Ukrainian Gran' AAM and the K-30 AAM:
Could be photoshopped though.

http://www.secretprojects.co.uk/forum/index.php/topic,283.0.html
 
In case anybody wants to check it out. . .
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Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #223 on: March 26, 2013, 10:23:34 am »
The layout doesn't prove anything also it is common amongst recent IR dog fighting missiles such as German IRIS-T and French MICA.
 
Isn't PL-10 a semi-active MRAAM based on Italian Aspide missile?
 

Offline JFC Fuller

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #224 on: March 26, 2013, 10:30:09 am »
The layout doesn't prove anything also it is common amongst recent IR dog fighting missiles such as German IRIS-T and French MICA.
 
Isn't PL-10 a semi-active MRAAM based on Italian Aspide missile?

Links between the Ukrainian and Chinese AAM industries have been documented in a number of places, the Chinese are said to still be reliant on the Ukraine for some key AAM components as well as design support.
« Last Edit: March 26, 2013, 11:46:24 am by JFC Fuller »

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #225 on: March 26, 2013, 10:47:06 am »
No, the Aspide-copy is the PL-11 ... PL-10 - once called PL-ASR - is the new SR-IR-AAM and long expected to be similar to (or even based on) the South African A-Darter.

« Last Edit: March 26, 2013, 10:50:41 am by Deino »
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #226 on: March 26, 2013, 10:51:53 am »
The missile in the photograph seems to have butterfly wing shaped tail fins similar to R-27 alamo's central fins, also it seem larger than typical short range AAM.
« Last Edit: March 26, 2013, 10:57:42 am by chuck4 »

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #227 on: March 26, 2013, 11:00:30 am »
What are those dots on the fuselage surface all around the missile bay?   Camera reference markers?
 
 

Offline flateric

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #228 on: March 26, 2013, 01:35:12 pm »
yes
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stealth, more than a few of them truly technically ignorant and proud of it." Sherm Mullin, Skunk Works

Offline PaulMM (Overscan)

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #229 on: March 26, 2013, 02:22:43 pm »
The missile in the photograph seems to have butterfly wing shaped tail fins similar to R-27 alamo's central fins, also it seem larger than typical short range AAM.

Possibly, but the level of distortion in the photo makes it hard to be sure. It may just be untapered.
 
As to size - maybe, I will do some scaling calculations tonight.
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Offline PaulMM (Overscan)

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #230 on: March 26, 2013, 02:52:11 pm »
The layout doesn't prove anything also it is common amongst recent IR dog fighting missiles such as German IRIS-T and French MICA.
 
Isn't PL-10 a semi-active MRAAM based on Italian Aspide missile?

Links between the Ukrainian and Chinese AAM industries have been documented in a number of places, the Chinese are said to still be reliant on the Ukraine for some key AAM components as well as design support.

Indeed. Note the wings are positioned further forward than on MICA or IRIS-T. Also, there are no known links between Chinese and Western AAM manufacturers, so its much less likely that there is any connection. Not saying that China didn't or couldn't come up with that design alone, but it would fit a general pattern of cooperation if there was some Ukrainian influence.
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Offline lancer21

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #231 on: March 26, 2013, 04:20:15 pm »
IF (and i emphasize that) the ukrainians have any part in this, like assistance or whatnot, their Gran missile seems to have a fairly similar configuration to PL-10. But then, so is Iris-T. Maybe it's just a configuration that serves best what the chinese want from this missile, without having any outside involvement in it. Either way , imo that PL-8 is becoming way too long in the tooth, wonder how far in development the PL-10 is .

Offline PaulMM (Overscan)

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #232 on: March 26, 2013, 11:27:01 pm »
I can't decide if the fins have reverse taper, or maybe have some curvature like the wrap-around fins on the BGM-110 cruise missile.

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Offline PaulMM (Overscan)

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #233 on: March 27, 2013, 01:03:58 am »
Here's a poor quality copy of the PL-10 picture from a 2010 AAM development roadmap of uncertain provenance. Added wings to the earlier A-Darter style layout, but tail is different from the missile on the J-20. If they are actually reverse taper, it may be to get greater control authority as it was on R-27 - with the cost of increased drag when used.
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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #234 on: March 27, 2013, 01:17:51 am »
Size appears to be roughly 2.9m length, depending on your idea of how big J-20 is.
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Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #235 on: March 27, 2013, 02:20:05 am »
Size appears to be roughly 2.9m length, depending on your idea of how big J-20 is.

What could fit - and even more that wide diameter - to my theory that the PL-10 we saw above (and as shown in my book  ??? ) was abandoned and replaced by a PL-8/9-based design with new control fins, TVC and so on.

Deino
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #236 on: March 27, 2013, 08:45:39 am »
A new video ..



Deino
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline Grey Havoc

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #237 on: March 27, 2013, 09:12:09 am »
Size appears to be roughly 2.9m length, depending on your idea of how big J-20 is.

What could fit - and even more that wide diameter - to my theory that the PL-10 we saw above (and as shown in my book  ??? ) was abandoned and replaced by a PL-8/9-based design with new control fins, TVC and so on.

Deino

This is just a theory mind, but what if, rather than being the PL-10 or another conventional missile, our mystery missile is actually some sort of expendable Electronic Warfare unit?
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Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #238 on: March 27, 2013, 09:31:51 am »
It looks like it has thrust vectoring.

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #239 on: March 27, 2013, 09:45:36 am »
This is just a theory mind, but what if, rather than being the PL-10 or another conventional missile, our mystery missile is actually some sort of expendable Electronic Warfare unit?

Yes, that's a theory - my theory - but honestly when I saw the Raptor with its side bays loaded with an AIM-9M for the first time and even if I would not know what a SR-AAM looks like, I think a SR-AAM is much more likely for an air dominiance fighter than some sort of "expendable Electronic Warfare unit" !  ;)

Deino
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline Trident

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #240 on: March 27, 2013, 11:37:23 am »
Size appears to be roughly 2.9m length, depending on your idea of how big J-20 is.

What could fit - and even more that wide diameter - to my theory that the PL-10 we saw above (and as shown in my book  ??? ) was abandoned and replaced by a PL-8/9-based design with new control fins, TVC and so on.

Deino
That's an interesting hypothesis! Over on the Keypublishing forum, somebody posted a close-up taken from below the airborne J-20 and I automatically suspected a fake , because the seeker looked remarkably like the one from the PL-8! Maybe the photo is genuine after all, and it's simply that your theory is correct?

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #241 on: March 27, 2013, 11:51:29 am »
That's an interesting hypothesis! Over on the Keypublishing forum, somebody posted a close-up taken from below the airborne J-20 and I automatically suspected a fake , because the seeker looked remarkably like the one from the PL-8! Maybe the photo is genuine after all, and it's simply that your theory is correct?

To admit that image is a FAKE and we all know several other images from this artist but since there are a few CG-artists with quite fine contacts to the manufactors it's quite possible that he knows more than we ... (at least more than me  :-[ !)

Deino
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
W.H.Auden (1945)

Offline PaulMM (Overscan)

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #242 on: March 27, 2013, 10:41:36 pm »
http://www.china-defense.com/smf/index.php?topic=5901.840


Very nice pic, sharpened a bit to bring out details.
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Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #243 on: March 28, 2013, 01:13:55 am »
Yes, that image was from a flight performed yesterday ... sadly with the bays closed and no PL-10 !

Besides that I'm a bit surprised to see these test in the publiac done at CAC ... I would have expected these to see - if ever - much later or done at the CFTE. MAybe we can see the main-bays loaded too soon.

These are two PL-10-drawings I found in a Chinese forum ...
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Offline PaulMM (Overscan)

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #244 on: March 28, 2013, 02:37:11 am »
Been double checking my measurements.

I calculated the ratio of length between missile and J-20 is about 6.7.

Now, using my old calculated length of 20.5m (without pitot) that gives a missile length of 3.04m.

I also calculated the length a completely different way and ended up closer to 19.5m (without pitot). That gives a missile length of 2.9m.

Deino's recent calculations giving 20.35m would imply missile is about 3.0m.

If the 22m length believers are right, then that gives a missile length of 3.28m.

I believe the true length of this missile is likely to lie in 2.9-3.0m range, which means the length of J-20 lies in the 19.5-20.5m range, and probably nearer the top end.

Lots of assumptions made, a clear side on image with the whole aircraft and missile in view would be handy.

For comparison:

IRIS-T - 2.936m
A-Darter - 2.98m
ASRAAM - 2.9m
AIM-9X - 3.01m
R-73 - 2.93m

I'm going to say PL-10 is ~3.0m.
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Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #245 on: March 28, 2013, 02:57:47 am »
...
I'm going to say PL-10 is ~3.0m.

What fits nicely to my theory again of being based on the PL-8's diamete/body, which is exactly 2.99m long !
He was my North, my South, my East and West,
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I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
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Offline VH

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #246 on: March 28, 2013, 10:28:09 am »
The missile firing sequence for J-20 if that is what is being seen with this complicated missile firing - deployment does not make sense.  Here is an analysis from a Chinese military site and I agree.


Comparing the F-22 firing a missile to the J-20 doing the same you have these steps
F-22
1. Setup the missile in the bay with the door closed.
2 Open door
3. Fires missile
4. Close door

J-20
1. Opens door
2. Moves missile outside
3. Closes door and setups missile at the same time
4. Fires missile
5. Moves missile launching rail back into bay.
Or
1. Setups missile while in the bay
2. Open door
3. Moves missile out
4. Closes door
5. Fires missile
6. Moves missile launching rail back into bay

Unless the intention for the J-20 is to hang the missile outside during the entire engagement. The F-22 setup is faster.
« Last Edit: March 28, 2013, 10:31:25 am by VH »

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #247 on: March 28, 2013, 10:48:13 am »
So what's the problem ? If each step requires the same time You might be correct - at the cost of RCS with the bays open for the Raptor - ... otherwise (and since we don't know the time of preparation) this discussion is completely irrelevant.

IMO it's more like ...

J-20 - F-22

1. Setups missile while in the bay with the door closed - Setup the missile in the bay with the door closed
2. Open door and at the same time missile moves out - Open door and at the same time missile moves out (what You forgot for the Raptor)
3.  Closes door (lower RCS) - Fires missile (RCS !! due to open bay)
4. Fires missileMoves missile launching rail back into bay and at the same time close doors
5. Moves missile launching rail back into bay and at the same time close doors - done

As such it all depends on what time You need and at what cost. Both solutions are a compromise and I think it's stupid to simply bash one of them without knowing the time and pros & cons of each solution.

Deino
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
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Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #248 on: March 28, 2013, 01:14:14 pm »
The J-20 arrangement seems to be designed to minimize the necessary open angle (maybe 30-40 degrees) of the missile bay door during missile deployment, while placing the deployed missile well clear of the arc of its canard deflection.   
 
F-22 style arranagement would seem to require the bay door to open to a high angle (nearly 90 degrees) to enable the missile to shot out through the middle of the missile bay door opening.    This would feature seem to be problematic on the J-20 if the J-20's canards were deflected downwards at a high angle.    Even if the missile or door doesn't foul the canards outright, at least the blast from missile motor would damage the carards.   
 
Perhaps specification for the J-20 specifically require the aircraft to carry out extreme combat maneuvers involving high AOA and large canard deflection while ready to fire its IR missiles instantly, hence the unusual arrangement.
 
The fact this unusual arrangement is present on a prototype and tested so early in development phase suggest the J-20 design devoted significant forethought right at the beginning to all aspects of close combat capability.   This further discredits the notion that it is a striker, and instead suggests the design requirements for its air superiority capability was thorough and ambitious.
 
 
« Last Edit: March 28, 2013, 01:35:38 pm by chuck4 »

Offline latenlazy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #249 on: March 28, 2013, 01:24:28 pm »
The missile firing sequence for J-20 if that is what is being seen with this complicated missile firing - deployment does not make sense.  Here is an analysis from a Chinese military site and I agree.


Comparing the F-22 firing a missile to the J-20 doing the same you have these steps
F-22
1. Setup the missile in the bay with the door closed.
2 Open door
3. Fires missile
4. Close door

J-20
1. Opens door
2. Moves missile outside
3. Closes door and setups missile at the same time
4. Fires missile
5. Moves missile launching rail back into bay.
Or
1. Setups missile while in the bay
2. Open door
3. Moves missile out
4. Closes door
5. Fires missile
6. Moves missile launching rail back into bay

Unless the intention for the J-20 is to hang the missile outside during the entire engagement. The F-22 setup is faster.

Alternatively, perhaps the more complicated missile firing sequence is a tradeoff for preventing the sudden drag penalty for when the sidebay doors open to fire. Instead, the J-20 could expose its missile the moment combat enters WVR, and maneuver with the missile exposed so that a sudden slowdown doesn't occur mid maneuver at the moment of fire.

Offline Dragon029

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #250 on: March 28, 2013, 02:18:43 pm »
If the J-20 were equipped with non-LOAL missiles for a sortie, would a seeker have a sufficient cone of visibility for accomplishing target acquisition? If so, I imagine that could be a major benefit for operations using backwards compatibility of older AAM's.

Offline VH

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #251 on: March 29, 2013, 10:29:52 am »
With J-20 you have to open the bay doors TWICE. Once to get the missile out of the bay exposing the missile rail, then you close the bay doors. Then you must open the bay again to retract the missile rail. F-22 opens the doors once, fires the missile and then closes the door. J-20 has a more complex sequence which translates into more chances for something to get jammed especially under high g-loads. As the old saying goes: KISS.


I'll bet that at some point the Chinese abandon their messy sequence and adopt a F-22 type firing arrangement.

Offline Deino

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #252 on: March 29, 2013, 12:02:39 pm »
Again... I think the engineers at CAC surely will know how that system works, what pros & cons it has and so on regardless Your assumption that is is too complex, takes too much time and will be replaced by a F-22-style system ... as such I leke these discussion simply for "playing" around with an idea but I we all are only free-time-analysts ... or did You propose a Raptor-style launching sequence at CA`C and were rejected ?

IMO the complexity is surely not a problem even under high-g loads and as such what counts is simply what time the whole circle needs from bay-opening to AAM-launch (even if You then have to open & close it again) and what You gain on RCS-reduction with a closed door.
He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever; I was wrong.
...
For nothing now can ever come to any good.
-------------------------------------------------
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Offline quellish

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #253 on: March 29, 2013, 12:11:33 pm »
IMO the complexity is surely not a problem even under high-g loads and as such what counts is simply what time the whole circle needs from bay-opening to AAM-launch (even if You then have to open & close it again) and what You gain on RCS-reduction with a closed door.

Maybe, but with that missile hanging out any gains from having the door closed may be lost.

Kind of odd that it landed with that hanging out. From what I am reading in the thread I can't tell - did it take off with the rail out?

Offline VH

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #254 on: March 29, 2013, 12:17:55 pm »
Again... I think the engineers at CAC surely will know how that system works, what pros & cons it has and so on regardless Your assumption that is is too complex, takes too much time and will be replaced by a F-22-style system ... as such I leke these discussion simply for "playing" around with an idea but I we all are only free-time-analysts ... or did You propose a Raptor-style launching sequence at CA`C and were rejected ?


Sorry but I would favor the experience and air-to-air know-how accumulated by Lockheed for decades over what CAC believes they know.

Quote
IMO the complexity is surely not a problem even under high-g loads and as such what counts is simply what time the whole circle needs from bay-opening to AAM-launch (even if You then have to open & close it again) and what You gain on RCS-reduction with a closed door.


Like you said its your opinion. Wonder what missile launching sequence the T-50 has chosen?

Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #255 on: March 29, 2013, 12:27:35 pm »
Again... I think the engineers at CAC surely will know how that system works, what pros & cons it has and so on regardless Your assumption that is is too complex, takes too much time and will be replaced by a F-22-style system ... as such I leke these discussion simply for "playing" around with an idea but I we all are only free-time-analysts ... or did You propose a Raptor-style launching sequence at CA`C and were rejected ?


Sorry but I would favor the experience and air-to-air know-how accumulated by Lockheed for decades over what CAC believes they know.

Keeping in mind that LM has the accumulated experience from the F-102, F-106, F-111, and YF-12 when it comes to internal bays. 
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Offline JFC Fuller

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #256 on: March 29, 2013, 01:33:34 pm »
Sorry but I would favor the experience and air-to-air know-how accumulated by Lockheed for decades over what CAC believes they know.

Sorry, but I would favour both Lockheed's and CAC's experience over that of an anonymous internet poster with an accumulative total of six posts on this forum, all in threads about China and all seemingly derogatory towards its intellectual and engineering capabilities. Especially considering that you seem not to understand that the trapeze mechanism used by the F-22 to launch it's missiles essentially achieves the same thing as the J-20's fold out launch rail.

As for "KISS", it's a twin-engined fifth generation fast-jet. "KISS" went out of the window in the requirements study. 


Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #257 on: March 29, 2013, 02:22:16 pm »
Again... I think the engineers at CAC surely will know how that system works, what pros & cons it has and so on regardless Your assumption that is is too complex, takes too much time and will be replaced by a F-22-style system ... as such I leke these discussion simply for "playing" around with an idea but I we all are only free-time-analysts ... or did You propose a Raptor-style launching sequence at CA`C and were rejected ?


Sorry but I would favor the experience and air-to-air know-how accumulated by Lockheed for decades over what CAC believes they know.

Keeping in mind that LM has the accumulated experience from the F-102, F-106, F-111, and YF-12 when it comes to internal bays.

When LM has also accummulated experiences with having to launch out of an internal bay under the sweep of a canard, like they didn't with F-102, F-106, F-111, and YF-12, then we'll talk.
 
« Last Edit: March 29, 2013, 02:26:24 pm by chuck4 »

Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #258 on: March 29, 2013, 02:40:07 pm »
Again... I think the engineers at CAC surely will know how that system works, what pros & cons it has and so on regardless Your assumption that is is too complex, takes too much time and will be replaced by a F-22-style system ... as such I leke these discussion simply for "playing" around with an idea but I we all are only free-time-analysts ... or did You propose a Raptor-style launching sequence at CA`C and were rejected ?


Sorry but I would favor the experience and air-to-air know-how accumulated by Lockheed for decades over what CAC believes they know.

Keeping in mind that LM has the accumulated experience from the F-102, F-106, F-111, and YF-12 when it comes to internal bays.

When LM has also accummulated experiences with having to launch out of an internal bay under the sweep of a canard, like they didn't with F-102, F-106, F-111, and YF-12, then we'll talk.

True.  China has to make sure there is clearance for the canard.  So most likely that is a less than ideal, compromised, solution. 
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Offline PaulMM (Overscan)

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #259 on: March 29, 2013, 02:47:04 pm »
I have to step in here. Wild generalisations and assumptions are being thrown around. We can't conclude this is an amazing piece of Chinese ingenuity that Lockheed stupidly missed out on, any more than we can say its a stupid error by naive Chinese engineers who should have copied the F-22 design or a poor compromise forced on them by circumstances.

Firstly, what do we know? A J-20 prototype is fitted with an interesting sidebay weapons pylon arrangement which allows the pylon to stay outside while the weapons bay closes.

Why might you do this? Leaving aside the very real answers "because its a prototype - the finished article might be different" or "this is just for test rounds without LOAL" - lets assume for the sake of argument that this is the final design for the weapons sidebay.

Well, it might just be that the J-20 has a requirement to allow lock on before launch (LOBL) as well as lock on after launch (LOAL), just like the F-22 does. Aircraft design is the art of compromise, of reconciling different requirements which pull in different directions. There is no "one true way" which is demonstrably superior to all other approaches. F-22 and J-20 have different solutions to providing LOBL capabilities to the missile.

Why would this feature (LOBL) be important to China if the PL-10 AAM has lock on after launch ability?

1) Maybe pK is slightly higher with LOBL.
2) Maybe LOAL won't be available until Block 2 PL-10 and version 3 of the onboard J-20 software.
3) Maybe in a confused fight LOAL risks higher fratricide rates.
4) Maybe you are in a war and you just ran out of  LOAL-capable PL-10s and need to use the stocks of PL-8/9 hanging around your airbase.
5) Maybe you want to be able to sell the J-20 to third parties but PL-10 is too secret to be exported with it so it needs to be able to fire PL-9.
6) Maybe leaving the AAM outside for the duration of WVR combat speeds up LOBL launch (no need to wait for the bay to open to lock on) and increases your chances of hitting fleeting targets of opportunity.
7) Maybe PL-10s are just damn expensive and you'd like to be able to use the cheaper PL-9 series as well.

The F-22 was designed to be able to fire AIM-9L/M. AIM-9X wasn't even an option initially. The F-22 uses an arrangement where, for LOBL, the weapons bay doors open and remain open. The launcher swings out so that the seeker of the AAM can locate the target. It locates the target, locks on, fires, then the launcher retracts and the bay doors close.

The J-20 arrangement seen on this prototype allows the weapons bay door to close, leaving the launcher outside and below the sidebay. The missile can then locate its target, lock on, fire, then the weapons bay doors open again to allow the launcher to retract.

Why might you do want the doors to close rather than stay open like on the F-22?

The J-20 has a canard in the near vicinity of the sidebay. It may be that having an open weapons bay door for an extended period restricts movement of the canard or causes nasty aerodynamic interactions between the two. This would make it advantageous to close the door as soon as possible.

Perhaps the area of the sidebay has undesirable airflow characteristics. This launcher puts the missile lower down on the fuselage side in a more benign environment.


Perhaps the requirement for quick launch were so severe they couldn't wait for bay doors to open so the only option was to make a launcher than can stay outside the whole WVR engagement allowing near-instant launch.

The appearance of this launcher on a prototype J-20 also does not preclude the ability to use lock on after launch missiles. For a start, there could be a second pylon arragement which ejects the missile directly without the drop-out rail. Even using the existing rail, without seeing the cycle in action its not possible to know if it is slower, or if it is slower, is that tactically significant when weighed against the benefits?

This topic is for analysis and speculation, but lets have informed speculation please.
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Offline JFC Fuller

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #260 on: March 29, 2013, 02:55:24 pm »
True.  China has to make sure there is clearance for the canard.  So most likely that is a less than ideal, compromised, solution.

I don't see how, the Chinese seem to be achieving everything they want to achieve without adding any additional mechanisms. The doors still 'only' open and close (just as they do on any other weapons bay) and the launch rail still moves out of the bay and then back in again in the same basic conceptual fashion as that on F-22/F-35. The only difference being that the door can seemingly shut again once the launch rail is extended but before the missile is launched- however that does not require any extra mechanical elements over the weapons bays on the F-22/35. We also do not know that the missile can not be launched with the door open, it is entirely possible that it can.

Offline Mach42

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #261 on: March 29, 2013, 02:55:41 pm »
I would think the pros are that it gives better clearance and on the purely speculative side the CAC design might be inherently more resistant to G-forces and thus can be more lightweight.

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #262 on: March 29, 2013, 03:29:06 pm »

True.  China has to make sure there is clearance for the canard.  So most likely that is a less than ideal, compromised, solution.

Any practical engineering solution must be a compromise.    The question is did the design compromise what is more important for what is less important.     Judging from the fact that CAC picked canard layout more than once, we may assume CAC designers thought giving the plane a canard layout was more important than giving it a F-22 like launch rail.     So the compromises of this launch rail design may well have been deemed to resulted in less compromised aircraft overall, at least in the estimation of CAC designer
 
 
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Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #263 on: March 29, 2013, 03:32:42 pm »
I would think the pros are that it gives better clearance and on the purely speculative side the CAC design might be inherently more resistant to G-forces and thus can be more lightweight.

Pure speculation.   Nothing suggests the J-20 rail arrangement is intrinsically structurally lighter or more rigid, and hence more resistent to G-forces.
 
I think the J-20 launcher arrangement is governed largely by the different launch parameters specified in its design specifications.
 

Offline VH

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #264 on: March 29, 2013, 04:01:15 pm »
Quote

Sorry, but I would favour both Lockheed's and CAC's experience over that of an anonymous internet poster with an accumulative total of six posts on this forum, all in threads about China and all seemingly derogatory towards its intellectual and engineering capabilities. Especially considering that you seem not to understand that the trapeze mechanism used by the F-22 to launch it's missiles essentially achieves the same thing as the J-20's fold out launch rail.


Remember the discussion is on how effective this missile launch scheme is in maintaining the stealth of this aircraft in an air combat situation. Can you address that issue? As others have pointed out having this missile hanging out of the aircraft increases the radar cross section of the aircraft.  This configuration with this missile is very much like hanging a missile from a pylon on a wing.

Offline latenlazy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #265 on: March 29, 2013, 04:44:08 pm »

True.  China has to make sure there is clearance for the canard.  So most likely that is a less than ideal, compromised, solution.

Any practical engineering solution must be a compromise.    The question is did the design compromise what is more important for what is less important.     Judging from the fact that CAC picked canard layout more than once, we may assume CAC designers thought giving the plane a canard layout was more important than giving it a F-22 like launch rail.     So the compromises of this launch rail design may well have been deemed to resulted in less compromised aircraft overall, at least in the estimation of CAC designer
 
 
.   
I'm splitting hairs a bit here, but for the solution to be a compromise one would have to assume some loss in functionality, or some form of inferiority. I haven't yet seen any compelling reason to assume those things. Couldn't it just be an equally functional/effective, or even a better approach?

Quote

Sorry, but I would favour both Lockheed's and CAC's experience over that of an anonymous internet poster with an accumulative total of six posts on this forum, all in threads about China and all seemingly derogatory towards its intellectual and engineering capabilities. Especially considering that you seem not to understand that the trapeze mechanism used by the F-22 to launch it's missiles essentially achieves the same thing as the J-20's fold out launch rail.


Remember the discussion is on how effective this missile launch scheme is in maintaining the stealth of this aircraft in an air combat situation. Can you address that issue? As others have pointed out having this missile hanging out of the aircraft increases the radar cross section of the aircraft.  This configuration with this missile is very much like hanging a missile from a pylon on a wing.

[size=78%] [/size]

Stealth isn't as important in wvr combat.
« Last Edit: March 29, 2013, 04:47:27 pm by latenlazy »

Offline JFC Fuller

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #266 on: March 29, 2013, 04:53:52 pm »
Remember the discussion is on how effective this missile launch scheme is in maintaining the stealth of this aircraft in an air combat situation. Can you address that issue? As others have pointed out having this missile hanging out of the aircraft increases the radar cross section of the aircraft.  This configuration with this missile is very much like hanging a missile from a pylon on a wing.

Just like when the F-22, F-35 and F-15 Silent Eagle weapons bays/launchers push their missiles outside the bay and through the boundary layer prior to missile launch. And you were not talking about radar cross section, you were talking about complexity, it has been pointed out to you that the system chosen by the Chinese is no more complex than that on the F-22.

And within WVR the J-20 would have the "stealth" (RCS, IR, & Visual) of a male peacock during courtship.

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #267 on: March 29, 2013, 04:55:46 pm »

Stealth isn't as important in wvr combat.


Not to mention a missile hanging out on a pylon would be more stealthy than a missile hanging out on a pylon with both bay doors open the entire time too ala F-22...

Offline VH

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #268 on: March 29, 2013, 07:45:43 pm »
Quote

Not to mention a missile hanging out on a pylon would be more stealthy than a missile hanging out on a pylon with both bay doors open the entire time too ala F-22...


FYI The time F22 consumes to open its side bay and fires its Sidewinder is measured in seconds. Check out any video of F22 firing its Aim-9 and see for yourself
« Last Edit: March 29, 2013, 07:51:18 pm by VH »

Offline VH

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #269 on: March 29, 2013, 07:50:07 pm »
Quote

Just like when the F-22, F-35 and F-15 Silent Eagle weapons bays/launchers push their missiles outside the bay and through the boundary layer prior to missile launch. And you were not talking about radar cross section, you were talking about complexity, it has been pointed out to you that the system chosen by the Chinese is no more complex than that on the F-22.



How did you arrive at that conclusion? And I am speaking about loss of radar cross section and complexity.

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #270 on: March 29, 2013, 08:08:20 pm »
Quote

Not to mention a missile hanging out on a pylon would be more stealthy than a missile hanging out on a pylon with both bay doors open the entire time too ala F-22...


FYI The time F22 consumes to open its side bay and fires its Sidewinder is measured in seconds. Check out any video of F22 firing its Aim-9 and see for yourself




See, so the point of your argument wasn't about stealth per se as much as time.
Of course, we don't know how quickly J-20 can fire PL-10 in a test environment as of yet, so your argument is moot.


Practically, for those of us bent on comparison,


1: How quickly would an F-22 would fire its sidewinder in a combat scenario?
2 (and more importantly): How quickly would J-20 fire its PL-10 in a comparable scenario, assuming both are firing LOBL or LOAL missiles.


If one day we get an answer for 2, and it turns out both J-20 and F-22 have SRAAM firing sequences of similar duration, then technically J-20 will be exposing less drag and less surfaces for reflection than F-22.

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #271 on: March 29, 2013, 11:30:52 pm »

True.  China has to make sure there is clearance for the canard.  So most likely that is a less than ideal, compromised, solution.

Any practical engineering solution must be a compromise.    The question is did the design compromise what is more important for what is less important.     Judging from the fact that CAC picked canard layout more than once, we may assume CAC designers thought giving the plane a canard layout was more important than giving it a F-22 like launch rail.     So the compromises of this launch rail design may well have been deemed to resulted in less compromised aircraft overall, at least in the estimation of CAC designer
 
 
.   
I'm splitting hairs a bit here, but for the solution to be a compromise one would have to assume some loss in functionality, or some form of inferiority. I haven't yet seen any compelling reason to assume those things. Couldn't it just be an equally functional/effective, or even a better approach?




The photo and CG rendering of j-20 mechanism suggests the launch rails are mounted rigidly to curved arms , which either pivot or travel on rollers during deployment to facilitate more complicated out and down motion.   F-22's launch rails are hinged to trapeze arms, which deploy when retracted collapse under the rails.    This suggests the f-22's lunch rails stow into a smaller package when retracted.

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #272 on: March 29, 2013, 11:47:14 pm »
Quote

Not to mention a missile hanging out on a pylon would be more stealthy than a missile hanging out on a pylon with both bay doors open the entire time too ala F-22...


FYI The time F22 consumes to open its side bay and fires its Sidewinder is measured in seconds. Check out any video of F22 firing its Aim-9 and see for yourself




See, so the point of your argument wasn't about stealth per se as much as time.
Of course, we don't know how quickly J-20 can fire PL-10 in a test environment as of yet, so your argument is moot.


Practically, for those of us bent on comparison,


1: How quickly would an F-22 would fire its sidewinder in a combat scenario?
2 (and more importantly): How quickly would J-20 fire its PL-10 in a comparable scenario, assuming both are firing LOBL or LOAL missiles.


If one day we get an answer for 2, and it turns out both J-20 and F-22 have SRAAM firing sequences of similar duration, then technically J-20 will be exposing less drag and less surfaces for reflection than F-22.


2 observationss and 1 reflection:


Due to the location of the rail, the seeker of an IR missile on the rail of a J-20 should have a substantially larger uninterrupted field of view than a seeker of an IR missile on the rail of an F-22.


J-20's design affords the option of stowing the IR missile for maximum stealth during BVR  combat, and also deploying the IR missile outside in an aerodynamically relatively clean configuration during WVR combat, when stealth can't be achieved anyway.   While so deployed othe IR missile can be fired even quicker than the missile on the f-22.   F-22's design does not afford similar options.   the missile is either stowed stealthily even when stealth can't be achieved, or deployed in an aerodynamically messy configuration.


Now the reflection.   LOAL is nice.  But I am not sure it is always desirable to fire a missile in the LOAL mode even if the missile is capable of LOAL mode.   For instance, in a very close range maneuvering fight, the distance the missile fired in LOAL mode may have to travel before it acquires a lock may put the target out of the field of view of the seeker.  Having the ability to carry the missile outside in relatively clean aerodynamic configuration to facilitate lock on before launch when situation demands it may be an advantage.

Offline latenlazy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #273 on: March 30, 2013, 12:32:10 am »

True.  China has to make sure there is clearance for the canard.  So most likely that is a less than ideal, compromised, solution.

Any practical engineering solution must be a compromise.    The question is did the design compromise what is more important for what is less important.     Judging from the fact that CAC picked canard layout more than once, we may assume CAC designers thought giving the plane a canard layout was more important than giving it a F-22 like launch rail.     So the compromises of this launch rail design may well have been deemed to resulted in less compromised aircraft overall, at least in the estimation of CAC designer
 
 
.   
I'm splitting hairs a bit here, but for the solution to be a compromise one would have to assume some loss in functionality, or some form of inferiority. I haven't yet seen any compelling reason to assume those things. Couldn't it just be an equally functional/effective, or even a better approach?




The photo and CG rendering of j-20 mechanism suggests the launch rails are mounted rigidly to curved arms , which either pivot or travel on rollers during deployment to facilitate more complicated out and down motion.   F-22's launch rails are hinged to trapeze arms, which deploy when retracted collapse under the rails.    This suggests the f-22's lunch rails stow into a smaller package when retracted.
Sure, but isn't the real gauge of how effective the solution is dependent on its performance as a weapons mount? What I'm getting at is whether the specific mechanism compromises deployment time, aerodynamic penalty, detectability, kill probability, etc etc. Even if the mechanism takes up more space, that's secondary to the actual performance of the solution.

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #274 on: March 30, 2013, 12:22:58 pm »
- snipped for brevity -


Good post! I would like to add only one point which affects most SRAAMs but is independent of LOAL/LOBL capability: such missiles are generally rail launched (rather than free-fall or ejector). I would expect the PL-10 to be no different, if nothing else to ensure backwards compatibility with legacy fleets (J-10, J-11).
All in all, I see the following other reasons as possible explanations for the novel weapons bay solution:
1. Interference between the door and canard if opened far enough to clear the missile. This could be either mechanical (if so, most likely for upward deflection, there are photos showing the bay door at least partially open during full downward canard deflection on the ground) or aerodynamic in nature.
2. Severe vibration induced by air flow over the open bay cavity which cannot be tolerated by the missile for long periods. As pointed out by you, it could be advantageous to extend the missiles as soon as the J-20 enters a short-range engagement and keep them ready to fire with minimum delay throughout the fight.
As for disadvantages, I don't really see any. Probably the biggest penalty will have been the research effort  to come up with this solution and then the development cost to validate it over a more conventional approach due to the increased risk inherent in adopting any untried solution.

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #275 on: March 30, 2013, 02:36:26 pm »
2 thoughts:


1.  It seems to me that severe aerodynamic vibration inside the open weapon bay may be more easily cured by some kind of simple movable spoiler or deflector that deploys with the bay doors, rather than a elaborate and novel rail deployment mechanism.


2.  It's not the rail launch that brings up the issue of LOAL/LOBL.  It's the fact that the ability to close the weapon bay doors with the rail outside suggest the design specifically intends to hold the missile in the airstream for a significant amount of time.   If the design simply calls for the quickest possible launch of the missile, there is no need to close the doors in the middle of the sequence.






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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #276 on: March 30, 2013, 03:00:00 pm »
2 thoughts:


1.  It seems to me that severe aerodynamic vibration inside the open weapon bay may be more easily cured by some kind of simple movable spoiler or deflector that deploys with the bay doors, rather than a elaborate and novel rail deployment mechanism.


F-117 and B2 both deploy a simple airdam into the slipstream when the bomb bay doors are open for that purpose


Quote
2.  It's not the rail launch that brings up the issue of LOAL/LOBL.  It's the fact that the ability to close the weapon bay doors with the rail outside suggest the design specifically intends to hold the missile in the airstream for a significant amount of time.   If the design simply calls for the quickest possible launch of the missile, there is no need to close the doors in the middle of the sequence.


Exactly. And the mystery remains as to why the J-20 was seen landing with their novel missile rail system still deployed. Did it jam up and fail to retract during a test?

Offline latenlazy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #277 on: March 30, 2013, 03:18:39 pm »
2 thoughts:


1.  It seems to me that severe aerodynamic vibration inside the open weapon bay may be more easily cured by some kind of simple movable spoiler or deflector that deploys with the bay doors, rather than a elaborate and novel rail deployment mechanism.


2.  It's not the rail launch that brings up the issue of LOAL/LOBL.  It's the fact that the ability to close the weapon bay doors with the rail outside suggest the design specifically intends to hold the missile in the airstream for a significant amount of time.   If the design simply calls for the quickest possible launch of the missile, there is no need to close the doors in the middle of the sequence.
And again, the intention to leave the missile in the airstream for a prolonged period, or at least the capability to do so, by itself is not necessarily indicative of issues with LOAL, especially if there are inherent advantages to adopting the particular mechanism, such as better launch of non LOAL missiles.

Exactly. And the mystery remains as to why the J-20 was seen landing with their novel missile rail system still deployed. Did it jam up and fail to retract during a test?
Unlikely? They would need to test the aerodynamic effects of the extended rail in all flight envelopes, including landing, with or without the intention to leave it exposed over a prolonged period of time.
« Last Edit: March 30, 2013, 03:33:29 pm by latenlazy »

Offline VH

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #278 on: March 30, 2013, 03:27:43 pm »
Using the F-22 and the F-23 as a yardstick I never saw a instance of those aircraft landing with side or bottom bays still open.  But maybe J-20 rolls different?

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #279 on: March 30, 2013, 03:37:43 pm »
Note that the F-22 won't have LOAL capability until 2015 at the earliest, which is 10 YEARS after IOC.
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Offline sferrin

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #280 on: March 30, 2013, 03:38:09 pm »
Using the F-22 and the F-23 as a yardstick I never saw a instance of those aircraft landing with side or bottom bays still open.  But maybe J-20 rolls different?

F-22 has landed with a side bay open.  There was a picture of it in one of Airtime Publishing's books. 
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Offline latenlazy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #281 on: March 30, 2013, 03:57:07 pm »
Using the F-22 and the F-23 as a yardstick I never saw a instance of those aircraft landing with side or bottom bays still open.  But maybe J-20 rolls different?
That's a bit beside the point. They would have to conduct tests like these in case of mechanical failure. The yf-23 probably never had to conduct those tests because the program was never picked up. I'm more than certain the F-22 would have had to land with its bays open as it was testing for certification.

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #282 on: March 30, 2013, 06:16:26 pm »
Also keep in mind that whether the cheek missile arrangement on the j-20 innovative and effective, or overly clever and ill considered, this arrangement in and of itself seem unlikely to have a great deal of impact on the overall effectiveness of the j-20, which remains essentially unknown.








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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #283 on: March 30, 2013, 07:16:17 pm »
Perhaps one of the reasons to have the launch rail exposed with the doors closed is to be able to carry missiles/munitions on that station that would not fit within the weapons bay? For missions when LO isn't required, just as the F-35 has the ability to carry external stores during such missions.

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #284 on: March 31, 2013, 06:02:00 pm »
Perhaps one of the reasons to have the launch rail exposed with the doors closed is to be able to carry missiles/munitions on that station that would not fit within the weapons bay? For missions when LO isn't required, just as the F-35 has the ability to carry external stores during such missions.

Now that is an interesting idea!

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #285 on: March 31, 2013, 09:26:56 pm »
Perhaps one of the reasons to have the launch rail exposed with the doors closed is to be able to carry missiles/munitions on that station that would not fit within the weapons bay? For missions when LO isn't required, just as the F-35 has the ability to carry external stores during such missions.


On the issue of carrying stores externally, would j-20, because of its reliance on lifting canards some significant distance ahead of the wing, suffer center of gravity issues if it carried a great deal of weight on pylons under its main wing?   The center of gravity and center of lift on that plane has to be substantially further forward relative to its aft mounted wings than on an aircraft with either normal layout, or more closely coupled canards like rafale and su-30?

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #286 on: March 31, 2013, 10:45:37 pm »
Erm... no.



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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #287 on: March 31, 2013, 10:50:44 pm »
Perhaps one of the reasons to have the launch rail exposed with the doors closed is to be able to carry missiles/munitions on that station that would not fit within the weapons bay? For missions when LO isn't required, just as the F-35 has the ability to carry external stores during such missions.

what would be the point? carrying external stores with the F-22 and F-35 mean additional munitions. but just carrying a missile on the outside instead of the inside doesn't seem that much of an improvement.

however i could see the extending mount be viable in turning the F-22 style side bays into a location that can be used to carry bombs and ground attack munitions. or possibly also gunpods and targeting/recon pods.

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #288 on: March 31, 2013, 10:53:55 pm »
Perhaps one of the reasons to have the launch rail exposed with the doors closed is to be able to carry missiles/munitions on that station that would not fit within the weapons bay? For missions when LO isn't required, just as the F-35 has the ability to carry external stores during such missions.


A munition that cannot fit into the side bay would be better off on a dedicated wing hardpoint I think. A weapon out where the SRAAM should be not only would result in clearance issues (imagine a 500kg LT-2 hanging there), but I doubt the pylon itself would be capable of supporting a weapon significantly heavier than the <100kg of your typicall SRAAM (again, think of a 500 kg LT-2 hanging there)

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #289 on: March 31, 2013, 11:01:18 pm »
Erm... no.


Well, the j-20's wings are even further to the rear than eurofighter's, to the point where the trailing edge is flush with the engine nozzles.    Visual inspection suggests j-20 has proportionally a lot more mass ahead of the wing than the eurofighter.     This suggest j-20's canards has a much larger lifting role than those of the eurofighter's, whose canards are comparatively much more control in function.  Otherwise the j-20 would never rotate to take off.


This means j-20's center of lift is further forward relative to the wing than eurofighter's, which means heavy loads carried under the wing would be more problematic.


Also, because j-20 has high mounted wings, unlike the eurofighter's low mounted wings and relatively flush belly, the j-20 can's actually carry a pylon as close to the fuselage and therefore as far forward under its wings as the eurofighter.  This would put the center of gravity of all external stores carried under j-20 wings further back relative to the wings than eurofighter's, which would further exacerbate the issue.

Offline chuck4

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #290 on: March 31, 2013, 11:10:07 pm »
Perhaps one of the reasons to have the launch rail exposed with the doors closed is to be able to carry missiles/munitions on that station that would not fit within the weapons bay? For missions when LO isn't required, just as the F-35 has the ability to carry external stores during such missions.


A munition that cannot fit into the side bay would be better off on a dedicated wing hardpoint I think. A weapon out where the SRAAM should be not only would result in clearance issues (imagine a 500kg LT-2 hanging there), but I doubt the pylon itself would be capable of supporting a weapon significantly heavier than the <100kg of your typicall SRAAM (again, think of a 500 kg LT-2 hanging there)


Perhaps the side bay was designed with an ECM pod in mind?   Stowed for stealth, deployed for when stealth won't work and you still have to do something to stay alive?
« Last Edit: March 31, 2013, 11:12:07 pm by chuck4 »

Offline kcran567

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #291 on: March 31, 2013, 11:14:56 pm »
Perhaps one of the reasons to have the launch rail exposed with the doors closed is to be able to carry missiles/munitions on that station that would not fit within the weapons bay? For missions when LO isn't required, just as the F-35 has the ability to carry external stores during such missions.


What if I take it a step further and offer that those are external hookups for stealthy mission pods such as the silent hornet would carry. extra fuel and/or mission pods and missiles. built in growth potential and large capacity to carry weapons stealthily. If they are developing these we will have to wait and see. Its something  to be checked into.

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #292 on: April 01, 2013, 12:24:33 am »
that's too much 'further'
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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #293 on: April 01, 2013, 12:43:19 am »
Perhaps one of the reasons to have the launch rail exposed with the doors closed is to be able to carry missiles/munitions on that station that would not fit within the weapons bay? For missions when LO isn't required, just as the F-35 has the ability to carry external stores during such missions.


A munition that cannot fit into the side bay would be better off on a dedicated wing hardpoint I think. A weapon out where the SRAAM should be not only would result in clearance issues (imagine a 500kg LT-2 hanging there), but I doubt the pylon itself would be capable of supporting a weapon significantly heavier than the <100kg of your typicall SRAAM (again, think of a 500 kg LT-2 hanging there)


Perhaps the side bay was designed with an ECM pod in mind?   Stowed for stealth, deployed for when stealth won't work and you still have to do something to stay alive?


At the point where stealth would be "useless" (that is to say, when an enemy is in WVR), chances are ECM will not be particularly useful either if the other side is going at you with ImIR guided SRAAMs. Not to mention the pods you would stow in there would be relatively small, and thus not particularly powerful... and you would probably be better off developing a stealthy casing for a dedicated ECM pod instead like what's been proposed for JSF. Of course, having an ECM pod there would also deprive your plane of a much important SRAAM of its own.


I think we shouldn't overthink it. It's just a weapons bay, designed for an SRAAM, likely exclusively PL-10. It just has a relatively novel firing sequence is all.

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #294 on: April 01, 2013, 09:38:55 am »
Targeting pod makes a lot of sense to me.  It is something you will need outside for a couple of minutes.  That is long enough that keeping the bay open carries large penalty, yet short enough that you wouldn't want to carry it externally.

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #295 on: April 01, 2013, 04:08:24 pm »
At the point where stealth would be "useless" (that is to say, when an enemy is in WVR),

Errr, no.   Some estimates suggest that by 2020, airborne radar would be able to detect stealth aircraft in the aircraft's best angles more than 25 NM away.    That's well beyond visual range.   It would be very well to have some ECM capability against this.
 

Offline latenlazy

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Re: Chengdu J-20 pictures, analysis and speculation Part II
« Reply #296 on: April 01, 2013, 08:15:01 pm »
At the point where stealth would be "useless" (that is to say, when an enemy is in WVR),

Errr, no.   Some estimates suggest that by 2020, airborne radar would be able to detect stealth aircraft in the aircraft's best angles more than 25 NM away.    That's well beyond visual range.   It would be very well to have some ECM capability against this.
I doubt that even with detection they would be able to maintain a lock.