Chengdu J-20 pictures, analysis and speculation Part II

[Ian33]

Beautiful. It's an absolute stunner.

Hat doffed to the Chinese.

 

[Sundog]

Supposedly, the chief designer of the J-20 has been dismissed from his post.

 

[Blitzo]

Supposedly, the chief designer of the J-20 has been dismissed from his post.

That was posted on SDF as well... The reality is more nuanced. There was a thought that it might be espionage related but that case was back in May, and instead it is suggested (edit, incomplete) to be related to a different case at the time.

Unfortunately the vagueness of this news meant that some Chinese language foreign media (DuoWei, NTDTV etc) are doing their usual anti Chinese narrative and trying to spin it in the weirdest way possible. I presume alert5 doesn't know that those sites are very poorly reputable.

 

[Grey Havoc]

Blitzo, a line or two from your last post is missing.


Via JasonJ over at Tanknet:

 

[FighterJock]

Blitzo, a line or two from your last post is missing.


Via JasonJ over at Tanknet:

About the above photo of the J-20's open weapon bay's doors, Wow those bay's are HUGE! B)

 

[kaiserd]

Blitzo, a line or two from your last post is missing.


Via JasonJ over at Tanknet:

About the above photo of the J-20's open weapon bay's doors, Wow those bay's are HUGE! B)

They certainly are wide but don't look especially deep.
Clearly hard to tell from this type of pic but not clear if as deep as a F35A/Cs bays (required for 2,000lb class weapons), looks abit closer in depth to the F-22s main bay. Like the F-22 the J-20 also needs space above these main bays for its side missile bays.

 

[Deino]

Here are a slightly different image of the open bay....

By the way; Yang Wei was not dismissed, but in fact promoted to vice president of China Aviation Research Institute & vice director of AVIC Science and Technology Commission.

 

[Blitzo]

By the way; Yang Wei was not dismissed, but in fact promoted to vice president of China Aviation Research Institute & vice director of AVIC Science and Technology Commission.

Well, that's one of the more credible rumours going around anyway.

But at this stage I'm not even certain if Yang Wei has even undergone any sort of change in position at all -- it is far too easy to talk about changes in personnel at AVIC or other Chinese industries without the ability to present any sort of concrete proof... so I'd wait for any official disclosures later instead.

 

[totoro]

They certainly are wide but don't look especially deep.
Clearly hard to tell from this type of pic but not clear if as deep as a F35A/Cs bays (required for 2,000lb class weapons), looks abit closer in depth to the F-22s main bay. Like the F-22 the J-20 also needs space above these main bays for its side missile bays.

Bays have been measured before, from numerous images. Main bays are roughly wide as ones on f22, 30ish cm longer than ones on f22 and deeper by as much as pl15 is wider than amraam (divided by 1,4 for rotating the missiles 45 degrees.), which seems to be 5-10 cm.

 

[Blitzo]

They certainly are wide but don't look especially deep.
Clearly hard to tell from this type of pic but not clear if as deep as a F35A/Cs bays (required for 2,000lb class weapons), looks abit closer in depth to the F-22s main bay. Like the F-22 the J-20 also needs space above these main bays for its side missile bays.

Bays have been measured before, from numerous images. Main bays are roughly wide as ones on f22, 30ish cm longer than ones on f22 and deeper by as much as pl15 is wider than amraam (divided by 1,4 for rotating the missiles 45 degrees.), which seems to be 5-10 cm.

I'm interested in getting more higher quality images of the open weapons bay of the 201X/LRIP planes to see if it is any slightly different in dimensions vs 2002's weapons bay from way back when.

 

[kaiserd]

They certainly are wide but don't look especially deep.
Clearly hard to tell from this type of pic but not clear if as deep as a F35A/Cs bays (required for 2,000lb class weapons), looks abit closer in depth to the F-22s main bay. Like the F-22 the J-20 also needs space above these main bays for its side missile bays.

Bays have been measured before, from numerous images. Main bays are roughly wide as ones on f22, 30ish cm longer than ones on f22 and deeper by as much as pl15 is wider than amraam (divided by 1,4 for rotating the missiles 45 degrees.), which seems to be 5-10 cm.

I'm interested in getting more higher quality images of the open weapons bay of the 201X/LRIP planes to see if it is any slightly different in dimensions vs 2002's weapons bay from way back when.

Thanks for the info lads, the relative lack of depth of the J-20's main bays does put the early speculation of the J-20 as a strike aircraft into perspective.
Appears no more skewed to that role than the F-22 (and less so than the F-35).

 

[Deino]

 

[Deino]

And now with four large drop-tanks ... maybe preparing to leave to Zhuhai ???

 

[sferrin]

A plane that big with 4 tanks is going to have a lot of range. A shame the F-22 never managed to fly with 4.

 

[sferrin]

Will they ever take it and the J-10 to Paris or Farnborough?

 

[latenlazy]

A plane that big with 4 tanks is going to have a lot of range. A shame the F-22 never managed to fly with 4.

Or maybe it's just not that big

 

[sferrin]

A plane that big with 4 tanks is going to have a lot of range. A shame the F-22 never managed to fly with 4.

Or maybe it's just not that big

What isn't that big? The J-20? It'd definitely got a lot more volume than the F-22.

 

[latenlazy]

A plane that big with 4 tanks is going to have a lot of range. A shame the F-22 never managed to fly with 4.

Or maybe it's just not that big

What isn't that big? The J-20? It'd definitely got a lot more volume than the F-22.

I think maybe about 10% more volume if we assume roughly the same cross sectional area, but a longer fuselage for the J-20. These things can be deceptive though. Small differences in cross sectional area multipled over a length could add up, plus we have to factor in the F-22's much larger control surfaces and potentially thicker wings compared to the J-20

Even if we assume the J-20 really is more voluminous though, drag coefficient and SFC of the engines could shave off range. I'm not saying the J-20 is short legged, just that there are too many unknowables to be certain.

 

[sferrin]

True. Would have been nice to get four tanks on the F-22 though. Tankers can only do so much, that's why you still see two or three tanks on Strike Eagles even though they've got the CFTs.

 

[Blitzo]

A plane that big with 4 tanks is going to have a lot of range. A shame the F-22 never managed to fly with 4.

I've seen some pictures and diagrams that seemed to depict F-22 as intending to fly with 4 fuel tanks -- was it never a requirement, or was the aircraft actually built with that capability but it's just never actually flown or tested with it before?

 

[totoro]

What isn't that big? The J-20? It'd definitely got a lot more volume than the F-22.

My personal volume measurements (from available images and scaling j-20 to be 20,5 m long) say Raptor is around 46 cubic meters while J-20 is around 56 cubic meters. If true, that'd be some 20% larger. How much of it is useful? Who knows... Longer intake ducts would eat up a large portion, i'd say 4-5 cubic meters. Larger weapon bays should take around 1 more cubic meters. Internal structure could go either way, though. Future engines might be a bit larger but who's to know. Anyway, I'd say there might be room for 3-5 cubic meters of internal fuel, over the volume F-22 has.

 

[sferrin]

What isn't that big? The J-20? It'd definitely got a lot more volume than the F-22.

My personal volume measurements (from available images and scaling j-20 to be 20,5 m long) say Raptor is around 46 cubic meters while J-20 is around 56 cubic meters. If true, that'd be some 20% larger. How much of it is useful? Who knows... Longer intake ducts would eat up a large portion, i'd say 4-5 cubic meters. Larger weapon bays should take around 1 more cubic meters. Internal structure could go either way, though. Future engines might be a bit larger but who's to know. Anyway, I'd say there might be room for 3-5 cubic meters of internal fuel, over the volume F-22 has.

1300+ gallons (9000lbs) is nothing to sneeze at.

 

[latenlazy]

What isn't that big? The J-20? It'd definitely got a lot more volume than the F-22.

My personal volume measurements (from available images and scaling j-20 to be 20,5 m long) say Raptor is around 46 cubic meters while J-20 is around 56 cubic meters. If true, that'd be some 20% larger. How much of it is useful? Who knows... Longer intake ducts would eat up a large portion, i'd say 4-5 cubic meters. Larger weapon bays should take around 1 more cubic meters. Internal structure could go either way, though. Future engines might be a bit larger but who's to know. Anyway, I'd say there might be room for 3-5 cubic meters of internal fuel, over the volume F-22 has.

Genuinely curious how you did your estimation. Wanna share methodology?

 

[totoro]

Using existing images of f-22, comparing them to existing drawings. Then, when i found most accurate drawings, decomposing them to several components. Wings, intakes, nose, tails, body, etc. Anything that i could turn into a hexahedron, a pyramid, a cone, etc. Then measuring each of those components. Then calculating their volume. Then adding all the volumes.

Yes, it does not give a precise figure, but that's not the point. I still believe i achieved margin of error less than 5%. Perhaps a bit more for J-20 as it lacks official dimensions so measuring it comes with own set of errors.

 

[Deino]

For all who thought it can't get better .... :

 

[Deino]

By the way there was yesterday an interesting post in a forum claiming:

According to the leader of 毛发党, the WS-15 has just finished the ground testing, and it is ready to pass the test on the IL-76 platform. While the current J-20A uses the AL-31FM2, a special customized edition of the AL-31, also a joint development between China and Salut, just like the GT25000.

Source: http://defence.pk/threads/chengdu-j-20-5th-generation-aircraft-updates-discussions.111471/page-416#ixzz4NMLotcnx

Therefore and like I said since so long: similar to the once and long still secret original AL-31FN-contract for the J-10 CAC chose a similar approach for the J-20. And since these are not exact AL-31FN Series 3, they were never mentioned or included in the number of engines reserved for the J-10B and J-10C.

Would be interesting to know the specific thrust of this engine. If it follows the regular FM2 about 142kN should be assumed.

Deino

 

[Deino]

... two more with the bays open ...

 

[sferrin]

For all who thought it can't get better .... :

It CAN get better- those pics could be wallpaper sized. Of all the stealth fighters, in looks I'd have to put this at #1. (Yes, yes, looks aren't everything.) The kid in me always thought the ATF would have produced something like this.

 

[kaiserbill]

Thanks for the pics and updates Deino.
I assume there will be a big "official" unveiling at the upcoming airshow I've read else where about?

 

[Trident]

Nice scheme - quite the looker indeed!

 

[bobbymike]

For all who thought it can't get better .... :

It CAN get better- those pics could be wallpaper sized. Of all the stealth fighters, in looks I'd have to put this at #1. (Yes, yes, looks aren't everything.) The kid in me always thought the ATF would have produced something like this.

Have to disagree not a fan the F-22 looks much nicer sleeker more modern.

 

[Sundog]

The YF-23 is still my favorite Stealth design and the T-50 is my favorite production (Soon, maybe) somewhat stealthy fighter. However, the J-20 does look like many of the ATF concepts that were released back in the eighties in all of those advanced aircraft articles and ads.

 

[sferrin]

For all who thought it can't get better .... :

It CAN get better- those pics could be wallpaper sized. Of all the stealth fighters, in looks I'd have to put this at #1. (Yes, yes, looks aren't everything.) The kid in me always thought the ATF would have produced something like this.

Have to disagree not a fan the F-22 looks much nicer sleeker more modern.

It's more nostalgia than anything. I remember scouring every magazine I could get my hands on, buying every book my poor, broke, high school self could afford, trying to guess what the "ATF" would look like. I was hoping for something "out there". You had Syd Mead's ATF robotic assembly line artwork, talk of things like "Pilot's Associate" (R2-D2 analog), etc. If they'd rolled out a J-20 I'd have thought, "yep, THAT'S what I'm talkin' about". Instead? "An F-15 with canted tails and a friggin' Bonanza!? WTF?" The first artwork I saw of the "real" designs were in Popular Mechanics. Of course that changed when I got my YF-23 rollout issue of AvWeek. My jaw was on the floor.

 

[bobbymike]

For all who thought it can't get better .... :

It CAN get better- those pics could be wallpaper sized. Of all the stealth fighters, in looks I'd have to put this at #1. (Yes, yes, looks aren't everything.) The kid in me always thought the ATF would have produced something like this.

Have to disagree not a fan the F-22 looks much nicer sleeker more modern.

It's more nostalgia than anything. I remember scouring every magazine I could get my hands on, buying every book my poor, broke, high school self could afford, trying to guess what the "ATF" would look like. I was hoping for something "out there". You had Syd Mead's ATF robotic assembly line artwork, talk of things like "Pilot's Associate" (R2-D2 analog), etc. If they'd rolled out a J-20 I'd have thought, "yep, THAT'S what I'm talkin' about". Instead? "An F-15 with canted tails and a friggin' Bonanza!? WTF?" The first artwork I saw of the "real" designs were in Popular Mechanics. Of course that changed when I got my YF-23 rollout issue of AvWeek. My jaw was on the floor.

Hey I would have picked the F-23 on looks alone. I collected all the books I could like Aircraft 2000, Future Fighters and dreamed of what the ATF would look like.

 

[icyplanetnhc (Steve)]

All fighters have their good and bad angles when it comes to aesthetic appeal. The J-20 is rather aggressive looking and its visuals make the plane look like it means business. F-22 is a tad on the conventional side in appearance, but certainly not bad looking. Sukhoi T-50 has a kind of elegance with its combination of sleekness and curvaceousness. Special mention goes to the F-23, which boasts amazing futuristic sleekness, though even that aircraft can look unflattering at times (like from the top looking forward, where the forward fuselage would appear disproportionately small).

 

[Dragon029]

Some high resolution images of the weapon bays:

 

[icyplanetnhc (Steve)]

Bay depth seems substantial, especially towards the middle in the longitudinal axis.

 

[Deino]

Bay depth seems substantial, especially towards the middle in the longitudinal axis.

Looks modified in comparison to the original demonstrator's bays ... and so the question remains: will now fit 3 PL-15 per bay ?

... IMO more likely than before !


Deino

 

[Deino]

... I need to correct myself ! ???

 

[totoro]

Bays themselves seem pretty much the same, dimension wise. doors have been changed, as well as some internal support structure. And possibly the rear part of the bay now has a slant surface (aerodynamic reasons?), if it didn't have it before.

Issue is still size of missiles. Each bay seems to be around 92 cm wide at its narrowest (hinge) and around 96 cm wide for most of the bay length.

Missile fin cross section seems to be around 37 cm. Now even if the bay figures are not precise, and bay is a bit wider, then missile is also wider as ratio of 92/96 to 37 is pretty precise from the available image.

Amraam is a narrower missile, with fin cross section being 316 mm. F-22's bay is around 95 cm wide at its widest. that is 32 to 95 ratio. Evidently, with 3 amraams inside a bay, and body diameter of 18 cm, it's arrangement is something like this:
3 cm space from bay wall to missile fin or 10 cm from bay wall to missile body. 18 cm for missile body. 10 cm from missile body to body of missile next to it (allowing for 3 cm of space between fins). 18 cm for the middle missile. another 10 cm for fins interlaping, another 18 cm for the third missile and another 10 cm from the missile body to the opposite wall. total of 94 cm.

Using similar clearances, if one wanted to stick 3 pl-12/15 missiles in the j20 bay we'd have: 3 cm of clearance from the wall to first missile, total of 9 cm from the wall to the missile body. 20 cm for missile body. 9 cm between two missile bodies (6 per fin set plus 3 for clearance between it and neighbouring missile body), then another 20 cm for middle missile, another 9 cm between two missiles, another 20 cm for third missile and another 9 cm from the third missile to bay wall. total of 96 cm.

I guess it is possible, though not guaranteed. On the other hand, if air superiority is main role of j-20, then the design would very much exploit the maximum and bays would be designed around air to air missiles primarely. In such a case it would be wasteful to have bays this wide if they're to carry only two missiles.

Of course, image measurement could be off by a few cm, so all this is far from conclusive.