Official Chengdu J-20 Discussion Thread

[Sampanviking]

King Comm,I think you touch on some very important aspects in your posts with regard general technological levels in the PRC.

One common theme in much of the media commentary (and indeed in some contributions to this thread) is the bizarre insinuation that because the J-20 project is at a stage that other projects were at 25 years ago, that somehow the PRC is still 25 years or a generation, behind the most developed countries.

Technological development is of course not linear or solid state and the general technological environment in the PRC is vastly different to that of other countries in the mid eighties. Two highly relevant areas in particular - material science and computing, have developed exponentially during this time, meaning that areas and precise technologies that were "cutting edge" then are everyday now. I am sure that the typical 3G phone has more computing power than many top range military systems from the late cold war. Likewise code writing has had decades of mass development to produce sub routines or the models thereof that are practically off the shelf.

The upshot of course is that the amount of actual development work is going to be considerably reduced and the time therefore required reduced in similar measure. Given quotes from the the PLA Brass and experience of Chinese project delivery, I would say that a initial production design should be ready by mid decade.

 

[gf0012-aust]

The canards on the Kfir do not serve as control surfaces, they are fixed.

Yes I know.

I have used 3 different aircraft with canards for a reason.

all 3 specifically use canards differently.

with respect to the Typhoon, I am unsure as to whats in the public domain.

I'm not sure how many more times I need to say this.......:eek

 

[latenlazy]

I'd be placing my money on what comes out of Dryden before I'd takes Gates definition. Politicians do like to dumb the debate down to sound bite denominators, the general public would be glazing over at the 2 minute mark. All the material that we see on future force structure deals with VLO and LO as a component element in future airforce and airfighting structure. Its one tool, but its a significant tool if you own the space and have it populated with your sensor grids, be they unmanned (GHawk), manned (Compass, Rivet, Guard etc...), CEC capability (Aegis), cross service comms and data shift (Link16, Link22) and atmospheric - out to space based radar. eg the USN alone has a bigger satellite constellation footprint capability than the russians - and the russians are a golden mile ahead of the chinese.

I wonder if that's still the case, considering how many satellite launches China has had in the last decade or so.

I'm also curious as to which aspects of the J-20 seem to be inconsistent with VLO to you, at least from what we can see in the pictures. Is it primarily just the ventral strakes and the canards?

 

[gf0012-aust]

I wonder if that's still the case, considering how many satellite launches China has had in the last decade or so.

china has less satellites in space than the USN - she's not even remotely close to the combined service satellite count, let alone adding in all the triple alpha agency satellites. China has a regional satellite capability and a partial global. She does not have any of the redundancy required to have a full overlapping racetrack constellation

I'm also curious as to which aspects of the J-20 seem to be inconsistent with VLO to you, at least from what we can see in the pictures. Is it primarily just the ventral strakes and the canards?

there are a number of things for me.

canards (in their own right) bugger up sig management. irrespective of what the "pretend" analysts are saying elsewhere (AvWeek, ELP, APA etc...) speak to anyone who does sig management and they will tell you the same. Physics is physics. boundary layers are boundary layers. nose, canards, main wings, and skegs are not sympathetic for preferred LO returns

cockpit untreated

IMO, that isn't DSI sitting on the test articles, they're shick ramps and are a legacy of the experiments done on FC-1.

don't get me wrong, I think its an admirable achievement and something that can be justifiably proud of, but I have significant doubts about whether these are pre-prod articles.

I think they're CTD's.

 

[t68]

IMO, that isn't DSI sitting on the test articles, they're shick ramps and are a legacy of the experiments done on FC-1.

don't get me wrong, I think its an admirable achievement and something that can be justifiably proud of, but I have significant doubts about whether these are pre-prod articles.

I think they're CTD's.

Pardon my ignorance but what does DSI/CTD refer to?

 

[latenlazy]

there are a number of things for me.

canards (in their own right) bugger up sig management. irrespective of what the "pretend" analysts are saying elsewhere (AvWeek, ELP, APA etc...) speak to anyone who does sig management and they will tell you the same. Physics is physics. boundary layers are boundary layers. nose, canards, main wings, and skegs are not sympathetic for preferred LO returns

Specifically for the J-20 or just in general? Do tailplanes affect LO returns less than canards? What about the size of those control surfaces? What do boundary layers have to do with LO returns? Why specifically are canards bad for LO returns in ways that tailplanes aren't (if that's the case). Sorry for all these questions, but as you can imagine specific information is hard to come by.

cockpit untreated

IMO, that isn't DSI sitting on the test articles, they're shick ramps and are a legacy of the experiments done on FC-1.

I thought the FC-1 used an DSI? What's the difference?

 

[Wang Dong]

there are a number of things for me.

canards (in their own right) bugger up sig management. irrespective of what the "pretend" analysts are saying elsewhere (AvWeek, ELP, APA etc...) speak to anyone who does sig management and they will tell you the same. Physics is physics. boundary layers are boundary layers. nose, canards, main wings, and skegs are not sympathetic for preferred LO returns
.

Let me pick your brains a bit more here. What could be going into the mind of the designers to include LO compromising features such as canards and ventral fins. Despite not having had experience in developing fighters of this type before, we can assume that CAC had access to software to calculate RCS, and have constructed an RCS pole model. Did they simply not realise these drawbacks - or were they presented with a set of constraints with relation to the technology currently available, the intended role of the aircraft, and what we see now is their compromise solution?

Building one or two prototypes is a very expensive undertaking.

 

[Aussie Digger]

Pardon my ignorance but what does DSI/CTD refer to?

DSI - Diverterless Supersonic Intakes. The type of air intake used on the F-35.

CTD - Concept Technology Demonstrator.

DSI intakes are the type of intake used on the F-35. Very stealthy and quite simple in operation with low weight and no moving parts, meaning lower maintenance requirements, but provide a 'relatively' limited maximum mach air speed whereas most air intakes that feature diverters are generally able to achieve much higher mach speeds, but are less good for LO purposes and are more maintenance intensive. As a generality...

A good article can be found here and illustrates exactly why China would be 'testing' this technology rather than being about to deploy it. DSI's are no mean aeronautical engineering feats...

http://codeonemagazine.dialogs.com/article.html?item_id=58


CTD's - A 'mule' that is designed to test various technologies, rather than something actually intended to be a capability at some point. Many people other than those excitable types Gary mentioned earlier think the 2x J-20 aircraft that China appears to have developed, are in fact little more than technology demonstrators rather than initial development examples for a type about to enter production, because of the seemingly conflicting design choices made with these aircraft.

What they do not do, is herald the end of anything and some of the claims being made about them are downright fanciful.

 

[Wang Dong]

I understand DSI is already featured on the latest batch of JF-17 inducted by the PAF.

 

[superchinese]

```

I found at a official websetAny relation with Mig-1.44 + F-35 + F-23 ?????

no no```it's just designed by ourselves ,and it's more beautiful than anyone you said above```

 

[superchinese]

I agree it will be a total ripoff of F-22, I have found somewhere pics of a chineese 5th generation fighter flying over some city and i will post it soon.
I read that actualy two seperate Chineese 5th generation fighter projects exists under development but Im not sure are they going to accept both (one cheapen to make up the numbers and other more sophisticated) or are they going to choose only one. Theirs economy is booming and money is not a problem.

you are right ! and actually, our govement have so much money ```

 

[Davyd]

I dunno. I just don't see it. There are certain things about it that don't strike me right. The hard chine at the nose to the intakes looks similar to the F-22, but it's like it "flows" wrong. Like the line of it is off, either for aerodynamics or stealth. It's vertical tails seem way too small. Even for.. scratch that. Especially for a prototype. LM made huge barn door sized tails for the YF-22, only shrinking them when they knew it would alright to do so. For a plane that large, i'd think even with the ventral strakes the tails should be larger. I'd also think that if stealth is what they were shooting for, the rear blended body to the rounded nozzles probably isn't the best. For one or the other reasons. . . Is it truly to be a striker? One would think so with the size. But does a strike aircraft needing stealth also need TV? Obviously the Chinese borrow a lot from Russian tech, so TVing would be in the form of rounded nozzles unlike the F-22. So it's a dogfighter then? HUGE for a dogfighter - or is this the 'Red' view of overkill coming back? Make it so large that it can shoot far more times than the enemy. Overall it just seems that they have a loooong way to go before this thing is finalized and ready for front line service. But it does seem to be a good start. They just wanted to get it out there for people to see and perhaps fear.

On a related note - that link in the previous post... Did you guys see picture 11? What's going on there? That looks like some pre-delivery F-22. But is that a Badger in the background? Does LM have a Badger of their own? Or has the US lost an F-22?

 

[Bonza]

On a related note - that link in the previous post... Did you guys see picture 11? What's going on there? That looks like some pre-delivery F-22. But is that a Badger in the background? Does LM have a Badger of their own? Or has the US lost an F-22?

I believe that picture's been discounted before as a photoshop effort, if I recall correctly.

 

[kwaigonegin]

Sorry, this is just nonsense.

RAM is discretely applied, usually to no more than 20% of a platforms surface area - it is applied to manage signal returns. You don't apply RAM to all of a surface area. In additon you have to manage the resultant signal return onto the next impacted surface area. In the case of 3 different boundary layer generators, that means that all 3 sets of leading edges as well as the skegs would need treatment or management - that is just a nonsense.

seriously, there is too much BS being written to make it sound technically feasible when basic awareness of fluid/aerodynamics, plus an understanding of how signals actually work would raise alarm bells.

you don't apply RAM to modify deflection angles - you would manage the end receiving point as well. RAM is not applied like bondo where you shape the surface to "signal mold" a return.

you could cover the entire plane in RAM and you'd still end up with a flying transducer....

FMD people are talking about RAM like its some magical goo that will fix all signals concerns - it doesn't.

so we now have some clown talking about applying RAM to the canards and ignoring the obvious signal transmitters that are sitting on the rest of the plane and which are independant of the canards as signal transmitters in their own right?

lastly decreasing swept area does not change RCS emission unless the overall design is sympathetic in the first place. hasn't anyone ever seen how big a B2 or even a B1 is? I'd argue that if you killed the single skeg on a B1 and canted twins onto it that you would get a lower RCS than whats on this platform.

HTF can this design be focussed on reducing signals returns and emissions when ist got conflicting management solutions in place?

the mind just boggles.... again, some of the technobabble being used to explain its signals integrity IMO is plain outright abject nonsense.

LOL you're right on. I'm no aerospace expert but even I know if you cover an entire 747 with RAM doesn't make it invinsible to radar!

 

[dingyibvs]

DSI - Diverterless Supersonic Intakes. The type of air intake used on the F-35.

CTD - Concept Technology Demonstrator.

DSI intakes are the type of intake used on the F-35. Very stealthy and quite simple in operation with low weight and no moving parts, meaning lower maintenance requirements, but provide a 'relatively' limited maximum mach air speed whereas most air intakes that feature diverters are generally able to achieve much higher mach speeds, but are less good for LO purposes and are more maintenance intensive. As a generality...

A good article can be found here and illustrates exactly why China would be 'testing' this technology rather than being about to deploy it. DSI's are no mean aeronautical engineering feats...

Article : Code One Magazine


CTD's - A 'mule' that is designed to test various technologies, rather than something actually intended to be a capability at some point. Many people other than those excitable types Gary mentioned earlier think the 2x J-20 aircraft that China appears to have developed, are in fact little more than technology demonstrators rather than initial development examples for a type about to enter production, because of the seemingly conflicting design choices made with these aircraft.

What they do not do, is herald the end of anything and some of the claims being made about them are downright fanciful.

You know, I can see why people think this is a TD precisely for the reason you mentioned. That is, it seems to have many conflicting design choices. However, if you study it closer, it appears that CAC has paid a lot of attention to make the contradictions work. Take the planform alignment for example, upon first inspection it looks like the trailing edges of the canards and the main wings aren't aligned, seemingly a sacrifice of stealth for the sake of maneuverability. However, if you take a closer look, it would appear that they are indeed aligned, except on opposite sides. That is, the left canard's trailing edge is aligned with the right wing's trailing edge. Similarly for the lateral edges.

Also, while canards in general are bad for stealth, it appears that they've tried their best to reduce that effect by playing the root of the canards inline with the main wings. In all, I think this plane shows a lot of attention to detail, more than upon initial inspection, and may very well be closer to the production model even closer than your average prototype.

 

[weasel1962]

Re: Sats

Googled sats arising from gf's post on sat capability.

US leads with ~440 sats in space. Russkis are 2nd with ~100 whilst China is catching up with ~67.

China has achieved close to 140 orbital launches to date (137). However, the number of PLA sats is equally misleading as a lot of milsats are small sub-orbital ones with limited duration and recoverable.

More importantly, China actually matched US for the 1st time in terms of space launches in year 2010 with 15 (2009:6 orbital). Many of which are for the beidou GPS which now has 7 sats. Beidou will eventually boast ~35 sats which will provide global coverage by 2020.

Other than beidou, the main Chinese sat programmes appear to include

Ziyuan/CBERS which provide imagery
Haiyangs which provide maritime surveillance
Micro Yaogans/ZPDS spy sats.

Possible 2011 launch schedule (~11 chinese launches)
Launch Schedule - 2011

 

[Feanor]

That's interesting. Russia is planning iirc 10 launches for the first quarter of 2011. I'm not sure how many of those are Russian domestic sattelites and how many are commercial launches.

 

[nangxi]

Today, 11th Jan. Chinese J-20 began it's first test flight at 00:50 PM (BEJING TIME), the plane landed safely at 01:11PM. the flying lasting about 18mins，the first test flight completed successfully.

Test pilot called Gang Li (李刚)

NOW WE CAN SAY: China has been the third country that has ablities to develop stealth fighter.

Some photos of first test flight link to netaddress(bbs.tiexue.net/post_4795880_1.html)

 

[SURB]

Here is an other image of J-20.
View attachment 4468
Well that cockpit looks similar (from a distance) to the one we were talking about and was displayed at airshow china isn't it?
View attachment 4471

View attachment 4472

 

[south]

J-20 Completes First Flight

apparently has flown.

:rel time for the crazies to come out of the woodwork.