Chengdu J-20 pictures, analysis and speculation Part II

[latenlazy]

If 20.5 meters is big...Still smaller than a flanker? I guess I should have asked what you meant by "big".

 

[latenlazy]

Oops. Accidentally quoted instead of edited.

 

[latenlazy]

Oops. Accidentally quoted myself instead of editing.

 

[Deino]

Here's one without the perspective problem. Judge for yourself.

Yup, still looks big. Thanks for proving my point. :

Yupp ... but that was never under discussion ! It was always clear that the J-20 is a "big" fighter ... but still smaller/ not as wide as a Flanker !

So what's Your point ??

Deino

 

[JFC Fuller]

Yupp ... but that was never under discussion ! It was always clear that the J-20 is a "big" fighter ... but still smaller/ not as wide as a Flanker !

So what's Your point ??

Deino

That it's big and thus looks big in photos, and we don't need an in depth analysis to demonstrate what we already know. But latenlazy felt like wasting a few posts so here we are.

 

[latenlazy]

Yupp ... but that was never under discussion ! It was always clear that the J-20 is a "big" fighter ... but still smaller/ not as wide as a Flanker !

So what's Your point ??

Deino

That it's big and thus looks big in photos, and we don't need an in depth analysis to demonstrate what we already know. But latenlazy felt like wasting a few posts so here we are.

Waste not want not, you and me both.

 

[Blitzo]

Yupp ... but that was never under discussion ! It was always clear that the J-20 is a "big" fighter ... but still smaller/ not as wide as a Flanker !

So what's Your point ??

Deino

That it's big and thus looks big in photos, and we don't need an in depth analysis to demonstrate what we already know. But latenlazy felt like wasting a few posts so here we are.

I'm not sure if you're aware, but the topic of J-20's size has become a somewhat touchy issue over the years for many, so even if you didn't know that and said J-20 was big in an off hand way, you could at least appreciate that Latenlazy's effort to elucidate on just how big it is.


Hey, at the very least you now have an objective comprehension of J-20's dimensions, something to refer back to...

 

[donnage99]

That it's big and thus looks big in photos, and we don't need an in depth analysis to demonstrate what we already know. But latenlazy felt like wasting a few posts so here we are.

Seems like someone dug a hole for himself and is trying to get out.

 

[Deino]

Sorry to step in, but these are exactly these stupid postings from - "honestly to say so - either stupid members or some, who simply want to troll around.

As such with so stupid posts like assuming some members might be "oversensitive" or "unable to understand an argument" ... or so I can really understand that some are getting angry, since strangely the only ones, who simply don not want to accept the facts or simply still want to stick to their own believes are the reason for such - in fact stupid - discussions.

I really can't understand why some still pretend to prefer to their eyeball estimations like "by the look at it in comparison relative to ..." even if we have hard facts by an - admitted slightly blurred - image which shows all three aircrafts in question side by side with the being J-15 substantially larger (= longer and wider) than the J-20 ??? ?

But since You are not that way, You can surely explain me how on earth could the J-20 be larger than a Flanker ??? ... even if this would contradict the wishfull-thinking of "it has to be larger than" of a few ??

Deino

 

[Deino]

I know, but since You were taking part on this discussion You can probably explain me why some still predend to say so simply since this is the reason why this "question" is so controversially discussed and some are maybe even a bit "over-sensitive" !

Anyway back to the J-20 ... here's a new video and it seems as if also the canards were cut in the corners similar to the tails.

http://v.ifeng.com/mil/mainland/2014002/0142c6cb-82ab-4bd7-b0bd-ba92832f90a7.shtml

 

[Deino]

That made my day

... and now just let this dragon fly !!

Deino

 

[FighterJock]

That made my day

... and now just let this dragon fly !!

Deino

Hope it does soon, the tension is killing me.

 

[Radical]

More J-20 pictures from SDF.

 

[flateric]

it's just my illusion or vertical tails chord somewhat reduced, too?

 

[sferrin]

it's just my illusion or vertical tails chord somewhat reduced, too?

If you look at the base they are turned a bit.

 

[donnage99]

So it seems that the ventral fins are there to stay? It may helps with IR reduction but I don't know about RCS especially from below

 

[Radical]

So it seems that the ventral fins are there to stay? It may helps with IR reduction but I don't know about RCS especially from below

There will be sacrifices. Exactly how much is hard to say, gotta actually test it.

 

[latenlazy]

So it seems that the ventral fins are there to stay? It may helps with IR reduction but I don't know about RCS especially from below

I kind of liken it to the F-22's inlet diverters. I also think of it as a trade off or break even for having smaller all moving tails. That yaw stability has to come somewhere. The F-22 has giant vertical tails for that exact purpose. On this front the PAK-FA is probably better than the F-22 and J-20 (I think they get their yaw stability from TVC and by controlling vortices with their LEVCON). Can't have everything.

 

[donnage99]

I kind of liken it to the F-22's inlet diverters. I also think of it as a trade off or break even for having smaller all moving tails. That yaw stability has to come somewhere. The F-22 has giant vertical tails for that exact purpose. On this front the PAK-FA is probably better than the F-22 and J-20 (I think they get their yaw stability from TVC and by controlling vortices with their LEVCON). Can't have everything.

The smaller all moving vertical tails may have been for reducing drag and not for RCS. Large or small surfaces don't really matter in term of RCS as much as the how angled these surfaces are. In fact, I think all moving vertical tails may hurt RCS since the breaks between control surfaces are exposed from frontal view.

 

[latenlazy]

I kind of liken it to the F-22's inlet diverters. I also think of it as a trade off or break even for having smaller all moving tails. That yaw stability has to come somewhere. The F-22 has giant vertical tails for that exact purpose. On this front the PAK-FA is probably better than the F-22 and J-20 (I think they get their yaw stability from TVC and by controlling vortices with their LEVCON). Can't have everything.

The smaller all moving vertical tails may have been for reducing drag and not for RCS. Large or small surfaces don't really matter in term of RCS as much as the how angled these surfaces are. In fact, I think all moving vertical tails may hurt RCS since the breaks between control surfaces are exposed from frontal view.

You're probably right about the tails primarily addressing drag, now that I think about it, but keep in mind that having stationary horizontal tails probably has the same impact as having those ventral fins, except perhaps the extra corner reflector.

I do think that you might need less deflection to achieve the same amount of side force with all moving tails, which might minimize the RCS impact, expose less surface back at the beam source. Although, we should also keep in mind that if the plane is deflecting its tails, unless it's braking it's probably turning, so then side aspect rcs might come into play, in which case it might be better to have smaller all moving tails than larger static ones? There's a reason why this is an experimental science and not a theoretical one! But I feel like I've made my point, mostly, about no design being perfect, and that was the more important bit I was trying to impart, I think.

 

[overscan (PaulMM)]

This image appears to be from a Chinese academic paper showing the reduction in RCS achieved from cutting off the corner of a canard. Allegedly, 3GHz, S-Band. (watermark obscures the legend).

 

[Deino]

 

[sferrin]

This image appears to be from a Chinese academic paper showing the reduction in RCS achieved from cutting off the corner of a canard. Allegedly, 3GHz, S-Band. (watermark obscures the legend).

I wonder if it helps with reducing vortex generation too (and if those can be seen on radar themselves). ???

 

[Kryptid]

This image appears to be from a Chinese academic paper showing the reduction in RCS achieved from cutting off the corner of a canard. Allegedly, 3GHz, S-Band. (watermark obscures the legend).

Interesting. Seems almost counter-intuitive to me (I had previously come to believe that fewer edges = better RCS).

 

[quellish]

Interesting. Seems almost counter-intuitive to me (I had previously come to believe that fewer edges = better RCS).

Yes, that is not true at all.

 

[Trident]

I kind of liken it to the F-22's inlet diverters. I also think of it as a trade off or break even for having smaller all moving tails. That yaw stability has to come somewhere. The F-22 has giant vertical tails for that exact purpose. On this front the PAK-FA is probably better than the F-22 and J-20 (I think they get their yaw stability from TVC and by controlling vortices with their LEVCON). Can't have everything.

The smaller all moving vertical tails may have been for reducing drag and not for RCS. Large or small surfaces don't really matter in term of RCS as much as the how angled these surfaces are. In fact, I think all moving vertical tails may hurt RCS since the breaks between control surfaces are exposed from frontal view.

You're probably right about the tails primarily addressing drag, now that I think about it, but keep in mind that having stationary horizontal tails probably has the same impact as having those ventral fins, except perhaps the extra corner reflector.

I do think that you might need less deflection to achieve the same amount of side force with all moving tails, which might minimize the RCS impact, expose less surface back at the beam source. Although, we should also keep in mind that if the plane is deflecting its tails, unless it's braking it's probably turning, so then side aspect rcs might come into play, in which case it might be better to have smaller all moving tails than larger static ones? There's a reason why this is an experimental science and not a theoretical one! But I feel like I've made my point, mostly, about no design being perfect, and that was the more important bit I was trying to impart, I think.

Actually thanks to the ventral strakes, the total vertical stabilizer surface on the J-20 is probably not that much smaller than on other contemporary fighters (and hence the drag advantage fairly moderate). Re-distributing some of that area below the roll axis should help reduce some roll/yaw coupling effects, rather than just relying on the flight control system to deal with them as the Typhoon and F-22 do. The T-50 must have been a pain to get right in this regard - which makes it all the more impressive how quickly and confidently they expanded its flight envelope. Sukhoi certainly seems to have the flight control aspect of fighter design nailed right down!

 

[latenlazy]

This image appears to be from a Chinese academic paper showing the reduction in RCS achieved from cutting off the corner of a canard. Allegedly, 3GHz, S-Band. (watermark obscures the legend).

I wonder if it helps with reducing vortex generation too (and if those can be seen on radar themselves). ???

Maybe not. My understanding of the reason they went with canards (and the dihedral arrangement) is in part to generate vortices for lift at high alpha.

 

[Deino]

Seems as if nothing was changed on the engines ... even if these sponsoons for the tails indeed look like to be a bit longer.

 

[Deino]

Following some relaible posters at the SDF the maiden flight is set for tomorrow !

 

[sferrin]

That is one good-looking plane.

 

[bobbymike]

That is one good-looking plane.

Agree but does anyone else get a chill seeing the prominent 'Red Star'. Feels like Cold War Redux.

 

[Blitzo]

That is one good-looking plane.

Agree but does anyone else get a chill seeing the prominent 'Red Star'. Feels like Cold War Redux.

I think it would look better, more modern if the roundels were shades of grey instead, like how USAF brands their fighters.

 

[overscan (PaulMM)]

Removed off topic posts.

 

[Sundog]

Agree but does anyone else get a chill seeing the prominent 'Red Star'. Feels like Cold War Redux.

Not really. When the cold war was going on the Soviet Union wasn't a favored nation trading partner and building all kinds of product for us. They also weren't letting average people talk to their people, much less higher ups. I talk to our Chinese suppliers all the time and our people go there and their's come here quite often.

What's going on over in China militarily right now seems more like "teenage super-power preening," more than anything else to me. Also, it was the Western economy that won the cold war, not the military itself. As such, with the U.S. and Chinese economy so intertwined, whatever happens will be very little like the Cold War era.

Though I must admit, their Red Star does look similar to the Soviet Union's Red Star.

Having said that, the J-20 is a nice looking airplane.

 

[Deino]

Finally ... more and better images surely soon !

 

[Deino]

Slowly they appear ...

 

[overscan (PaulMM)]

Some more ground shots. Canards have the same edge treatment as the vertical fins and ventrals.

 

[Deino]

They are getting better ... these tail sponssons seem to be different !

 

[overscan (PaulMM)]

And LERX appears to be straightened. Just a couple of spotters hanging about


[very slightly higher res]

 

[latenlazy]

And LERX appears to be straightened. Just a couple of spotters hanging about


[very slightly higher res]

The LERXes in front of the canards seem to be gone. I kinda miss them. Clearly the adjustments to the J-20's aerodynamics weren't exactly tiny (or those tiny LERXes just didn't matter that much).