Chengdu J-20 news and analysis Part III

[LowObservable]

Flow visualization!

Is the aircraft in the upper two images actually inverted?

 

[latenlazy]

Flow visualization!

Is the aircraft in the upper two images actually inverted?

Nope, completely different angles. The top one is from last year’s Zhuhai Airshow. The bottom one is presumed to be from testing. We have a few other photos that give us some sense of the plane’s vortical flow patterns.

 

[Deino]

Better now ?? (via SDF)

 

[DWG]

A couple of thoughts.

1) I think the centre J-20 is at a very slight angle to the runway centreline.

2) The varying distortion can be seen if you look at the open canopies. Slight on the rear J-20 pair, marked on the right-rear J-16.

3) The difference in distortion on the rear J-20 canopies (n.b. not the mirroring, the fact the mirroring isn't identical), despite both aircraft being aligned on equivalent runway block joints, seems to indicate the camera aimpoint was slightly off the centreline.

 

[Trident]

Better now ?? (via SDF)

Why, sure ;D

 

[overscan (PaulMM)]

Regardless of method, it won't be that precise with photo analysis. 12.9m span, 20.9m length is the estimate.

 

[Blitzo]

Better now ?? (via SDF)

Selecting the right photo is good

For future reference and anyone else who is not aware:

 

[TomcatViP]

Humm.... Sat alt should turn metric perspective flat... Deino, sorry but this view is... a fake :-\

 

[Blitzo]

Humm.... Sat alt should turn metric perspective flat... Deino, sorry but this view is... a fake :-\

The photo was taken from a drone, not a satellite ;D

c'mon, not that hard to figure out...

 

[sferrin]

Humm.... Sat alt should turn metric perspective flat... Deino, sorry but this view is... a fake :-\

That's not from a satellite. Probably from a quad-rotor "drone".

 

[LowObservable]

Pretty obvious from the start, hence the argy about measurements from lower-rez satellite photos. Not only is this from a wide-angle lens, but to add to the fun it looks as if it might be a non-symmetrical crop.

 

[latenlazy]

Pretty obvious from the start, hence the argy about measurements from lower-rez satellite photos. Not only is this from a wide-angle lens, but to add to the fun it looks as if it might be a non-symmetrical crop.

There are *lots* of problems with using this picture to get measurements, but until we have something better this the best we can do.

 

[TomcatViP]

Pretty obvious from the start, hence the argy about measurements from lower-rez satellite photos. Not only is this from a wide-angle lens, but to add to the fun it looks as if it might be a non-symmetrical crop.

Could be an after effect.

 

[sferrin]

https://www.youtube.com/watch?v=tDwKp_eoZv4

https://www.youtube.com/watch?v=7fQQwuukAac

 

[sferrin]

Awesome.

 

[Airplane]

Awesome.

Every time I see a pic of that plane it just looks so godly oversize... Its like an f-22 went on a cycle of nandrolone and testosterone. But as I understand its that big because its an uber long range power projection tool.

Has anyone, some whiz kid, done a hypothetical rcs calculation?

Forgive a naive question, but have the chicoms ever announced the total planned buy?

 

[Blitzo]

Awesome.

Every time I see a pic of that plane it just looks so godly oversize... Its like an f-22 went on a cycle of nandrolone and testosterone. But as I understand its that big because its an uber long range power projection tool.

Considering the aircraft is basically meant to be an F-22 with longer range... it shouldn't be a surprise.

If anything, when thinking about the westpac threat environment that both sides will face and the likely dearth of air refuellers and forward air bases, imo it is the F-22 which looks small and under sized for that area of operation rather than J-20 as over sized.

Has anyone, some whiz kid, done a hypothetical rcs calculation?

Depends on what your opinion of Carlo Kopp is.

Forgive a naive question, but have the chicoms ever announced the total planned buy?

Nope. if they did that would be an exception to the rule.

 

[Blitzo]

Awesome.

Every time I see a pic of that plane it just looks so godly oversize... Its like an f-22 went on a cycle of nandrolone and testosterone. But as I understand its that big because its an uber long range power projection tool.

Considering the aircraft is basically meant to be an F-22 with longer range... it shouldn't be a surprise.

If anything, when thinking about the westpac threat environment that both sides will face and the likely dearth of air refuellers and forward air bases, imo it is the F-22 which looks small and under sized for that area of operation rather than J-20 as over sized.

The F-22 was designed for the NATO theater which is much smaller. A shame they could never get four tanks working on the F-22. FB-22-1 below would have been more useful for the Pacific theater.

Four EFTs would be helpful in enhancing ferry range to theatre, but I'm not sure about operating in theatre with EFTs during combat missions for a stealth aircraft.

J-20 can carry four EFTs and I would be surprised if it ever carries them outside of Chinese airspace defended by IADS during a high end conflict.


In any case, I think between the YF-22 and YF-23, the latter's greater size and longer range would've made it more suitable for the pacific theatre that we see now.
The J-20 IMO is very much the result of an aircraft that wants to be able to compete with F-22 as close as it can get in certain performance parameters while exceeding it in endurance and range.

 

[Deino]

Off-topic posts deleted ... X-44, FB-22 and PCA are all irrelevant to the J-20.

Stay on topic please.

Deino

 

[Triton]

"China appears to have rushed its J-20 stealth fighter into service with an 'embarrassing' flaw"
by Alex Lockie

February 12, 2018

Source:
http://www.businessinsider.com/china-j-20-stealth-jet-fighter-rushed-embarrassing-flaw-2018-2

 

[sferrin]

As soon as they fix the engine they're back in business. Even with the original engines they'll still be a headache for the West.

(Nice turn there at 0:24)

https://www.youtube.com/watch?v=lCWoRK2L_Xg

 

[SpudmanWP]

That all depends on it the "stealth" is any good, how good the LPI modes of the radar are, and how well the electronics can stay EMCON (ie don't leak).

 

[sferrin]

That all depends on it the "stealth" is any good, how good the LPI modes of the radar are, and how well the electronics can stay EMCON (ie don't leak).

Yes, but I can't imagine it's not better than the Su-35.

 

[sferrin]

More pics.

 

[duker]

Could be those looking for the antecedents to the J-20 should be looking in Moscow not Fort Worth

As this article which is quoting long time British expert Jim Smith and is in Hushkit shows this comparison with the MiG 1.44 tactical fighter design of the 1990s. It first flew in 2000.

"The theory goes that China bought research data and possibly worked with MiG to create the J-20."

https://hushkit.files.wordpress.com/2018/01/j-20-mig-144.jpg?w=830

Of course the forward fuselage is completely different
"The J-20 uses the Lockheed Martin model for reduced radar conspicuity. The Raptor-like forward fuselage, angle alignment and F-35-style inlets are a far cry from the squashed forward fuselage and underslung box intake arrangement of the MiG....... Not everything can be judged from the outline of an aircraft, and is possible that much in the way of internal structure or materials was directly informed by the Russian aircraft."

The rest of the article here
https://hushkit.net/2018/01/03/ask-the-expert-what-does-the-j-20s-configuration-reveal/

 

[sferrin]

LM for the tech and shaping, Russia for the overall design. (Yes, yes, China has competent engineers.)

 

[Ainen]

...
J-20 can carry four EFTs and I would be surprised if it ever carries them outside of Chinese airspace defended by IADS during a high end conflict.


In any case, I think between the YF-22 and YF-23, the latter's greater size and longer range would've made it more suitable for the pacific theatre that we see now.
...

To be fair, I am not even sure if unrefueled range of J-20 is that large to call it especially long-legged, heavy usage of EFTs for clearly non-frontline configuration sujests it can be actually not that large.
Otherwise, why so many? Addition of this capability doesn't come for free.


The further, the more it seems what J-20 is quite pure air superiority bird with only secondary a2g or anything else.

 

[duker]

Smith thinks the particular configuration - the delta- allows more fuel and a broad under fuselage gives a longer weapons bay.

And looking at the Chinese strategic outlook anti ship missiles are going to go hand in hand with long range or if you are thinking of anti air weapons, then long range missiles against AWACS or tankers come into the picture.

 

[litzj]

Chinise are already familiar with canard delta configuration

because of j10. j20 seems like twin stealth ver. of j10 to me.

base of j10 is LAVI not mig 1.44.

my speculation is not official.

 

[duker]

So completely different in scale to J-10.

Historically China has a culture of copying other designs ( yet likely their engineers are just as competant as other countries, maybe just to hurry development along which happened with the MDD F18 versions).
Best example is the JF-17 which can be traced back via earlier version to the Mig -21. And even then they had help from Grumman for the modifications to move inlet from nose to wing roots

 

[Ainen]

Smith thinks the particular configuration - the delta- allows more fuel and a broad under fuselage gives a longer weapons bay.

But it's Bay is as long as it's necessary to comfortably fit current bwr missiles(pl-15).
Heavy usage of dtop tanks(as well as proliferation of Flanker family) sujests what internal range isn't that great either.

 

[duker]

I dont think Ive seen a photo of the J-20 with drop tanks ?

And this comparison image of the J-20 with Su-27 , Pak-FA and F-22 shows its a bigger plane than the F-22, and along with commentary of the design expert I mentioned, supports the large internal fuel.

https://i1.wp.com/fightersweep.com/wp-content/uploads/2016/09/size-chart.jpg?resize=1024%2C516&ssl=1

 

[sferrin]

I dont think Ive seen a photo of the J-20 with drop tanks ?

See page 2 of this topic.

 

[kcran567]

Have seen the pictures months ago and pondering them...seems like the Chinese want "Global self-deployment" capability. J-20 can Ferry itself anywhere without a refuel? Range and fuel fraction alone clean is probably higher than any other 5th Gen machine out there.

 

[Blitzo]

I dont think Ive seen a photo of the J-20 with drop tanks ?

And this comparison image of the J-20 with Su-27 , Pak-FA and F-22 shows its a bigger plane than the F-22, and along with commentary of the design expert I mentioned, supports the large internal fuel.

https://i1.wp.com/fightersweep.com/wp-content/uploads/2016/09/size-chart.jpg?resize=1024%2C516&ssl=1

That comparison image was one of the first made back when prototype 2001 came out and nobody knew how big it really was. In other words, that comparison is wrong.

This one from CSIS is much more accurate.

 

[Blitzo]

...
J-20 can carry four EFTs and I would be surprised if it ever carries them outside of Chinese airspace defended by IADS during a high end conflict.


In any case, I think between the YF-22 and YF-23, the latter's greater size and longer range would've made it more suitable for the pacific theatre that we see now.
...

To be fair, I am not even sure if unrefueled range of J-20 is that large to call it especially long-legged, heavy usage of EFTs for clearly non-frontline configuration sujests it can be actually not that large.
Otherwise, why so many? Addition of this capability doesn't come for free.


The further, the more it seems what J-20 is quite pure air superiority bird with only secondary a2g or anything else.

I'm not sure what you mean by "heavy usage of EFTs for clearly non-frontline configuration".

As you describe, four EFTs are obviously a non-frontline configuration, meaning the addition of those four EFTs is for other purposes, such as ferry in safe environments. There will obviously be situations where having four EFTs may be useful, and it makes sense to flight test that configuration.

Whether an aircraft is able to carry four or two EFTs or whatever I think should have no implication for what we estimate its internal fuel capacity is.

 

[Ainen]

Whether an aircraft is able to carry four or two EFTs or whatever I think should have no implication for what we estimate its internal fuel capacity is.

Ability to carry 4 fuel tanks requires additional complication of fuel system.
No one will do it without a proper reason. Even more so for a 5th generation fighter.

Simplest possible reason is a ferry range, of which they want really a lot(5500 was quoted by Xinhua).
Without these EFTs we just drop 8+t of fuel out of equation. Which basically is a full Raptor worth of fuel.

 

[totoro]

F-22 is internally configured to carry up to four tanks. But in the end they never tested for four, only two.
F-35 is plumbed for two tanks, never tested though.
Su-35 same as above, two tanks, never tested.

Range is certainly something Chinese require as A) they gravely lack in air refueling capacity, and B) their operational requirements likely include ability to operate at first island chain line, meaning up to 450 nm away from coastline. If one wishes to operate from bases more inland, to protect them from enemy attacks, that may add further few hundred nm to range requirement.

I will repeat one of my older posts:
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.

So i don't believe it's implausible J-20 carries 35% more fuel than F-22 internally, if not more. The four tanks seen would add to that. They seem to be sized pretty close to US 600 gallon tanks, so that would add another 7+ tons. Of course, actual range is hard to predict, fuel consumption may be somewhat worse than F-22.

 

[sferrin]

So i don't believe it's implausible J-20 carries 35% more fuel than F-22 internally, if not more. The four tanks seen would add to that. They seem to be sized pretty close to US 600 gallon tanks, so that would add another 7+ tons. Of course, actual range is hard to predict, fuel consumption may be somewhat worse than F-22.

Just look at the difference in fuel load between the YF-22 and the F-22A, and they were pretty much the same size.

 

[Ainen]

So i don't believe it's implausible J-20 carries 35% more fuel than F-22 internally, if not more.

Yes, I feel it to be like this too.Maybe a bit smaller.
Basically, it brings us to the typical 5th generation internal range window.
Raptor is just below it, because of changes between YF-22 and F-22A.