Chengdu J-20 5th Generation Aircraft News & Discussions

[antonius123]

My take is that the J-20 -- planform wise -- is not a compromise but an improvement from the 1.44...

To include aerodynamics from the Rafale...

Some focused on the Rafale's single vertical stab and that missed the point completely regarding adoption of diverse sources to make an improvement.

You still can say Mig 31 is an improvement of Mig 25, F-16block 60 is an improvement of F16A, or at farthest Mirage 4000 is improvement from Mirage 2000, since the airframe is not much different

But with the case of Mig 1.44 vs J-20 where the airframe is totally diferent (likewise the planform), we can not say j-20 is an improvement of Mig 1.44/Rafale/Typhoon/Grippen/J-10.

What you are showing above is only wing configuration similarity, but the airframe is glaringly different. Internalizing is not about improvement but require redesigning and totally change the airframe; not to mention the air intake, and continuous curvature.

Besides, why are you pushing your "emulating/improvement" idea on J-20 vs Mig 1.44 so vehemently? Because improvement/evolution is much more suitable explanation on PAKFA vs Flanker by far; as the planform similarity is so obvious

 

[SQ8]

My take is that the J-20 -- planform wise -- is not a compromise but an improvement from the 1.44...

To include aerodynamics from the Rafale...

Some focused on the Rafale's single vertical stab and that missed the point completely regarding adoption of diverse sources to make an improvement.

But it does seem that the JAST was an inspiration(or that the JAST was also inspired in a similar fashion??)..

I think the delta platform commonality is not a justification for taking the Rafale as an inspiration..although I do see your point regarding planform shaping especially the blended fuselage and leading edge.

Which does open up a canard discussion..
leaving the saucers and the flying wings aside.. are there no other conventional stealth designs other than those following the F-22 pattern?

 

[amalakas]

That may have provided a basic avionics databook.. but the refinements in design clearly have an American hue to them.
It may have been a case of "Lets take that idea and that idea and make this"..rather than "lets see how we can make this better".

I am not sure of the 3D TVC engine theories since there was a 2D TVC engine made for a fighter of the J-10 class(from a PAF source) but it was 1.4 times heavier than its conventional counterpart and not feasible yet. The Chinese may or may not have made improvements then.. but this is recent news to me so I do not expect a Chinese TVC anytime soon.
I see the J-20 relying more on its aerodynamics .. and possible breaking its canard RCS limiters when needed..
Although I imagine the result on a radar scope would show up like a blinker going on and off.

An interceptor or rather penetrating interceptor may have the capacity to get close enough to High value aerial force multiplier assets and pose a serious threat even with escorts present. The Russians had this idea with the mig-25 when the E-3 first came into the scene I think... having it zoom climb above escorts and launch R-40's at high speed toward the E-3.
While such a doctrine was simplistic at best.. a relatively stealthy attacker using a dogleg course could make it close enough to launch Passive homers at an Electromagnetic powerhouse such as an AEW&C system.
The same logic could be applied to execute attacks on bases such as Kadena and fly outside of detection ranges of Aegis missle pickets and the like to take out key targets on the ground.

But would you have a dedicated design for such a mission? Russia had a need for the MiG-25 because of its sheer vastness. So using a tool already there to do something else is sensible. Making a specialized tool from scratch ... a bit harder and consuming. No ?

 

[SQ8]

But would you have a dedicated design for such a mission? Russia had a need for the MiG-25 because of its sheer vastness. So using a tool already there to do something else is sensible. Making a specialized tool from scratch ... a bit harder and consuming. No ?

There are dedicated designs already for specialized strike missions.
And the vast amount of territory China would have to cover over sea to hit adversary assets..
and not to mention the possibility of striking south into India as well.
I think the J-20 is a good tool.

 

[Audio]

In my opinion there are only 2 options:
interceptor or strike fighter along the lines of the F-111, possibly one of the counters to carrier groups and/or a supplement to the J-8's.
I would argue against a pure technology demonstrator in light of the recent unveilment of the 2nd prototype ie. to prove a technology you shouldn't need 2 aircraft.
A mix of the two is also possible.

 

[amalakas]

There are dedicated designs already for specialized strike missions.
And the vast amount of territory China would have to cover over sea to hit adversary assets..
and not to mention the possibility of striking south into India as well.
I think the J-20 is a good tool.

True there are. Strange though that the strike plane came first then.

In my opinion there are only 2 options:
interceptor or strike fighter along the lines of the F-111, possibly one of the counters to carrier groups and/or a supplement to the J-8's.
I would argue against a pure technology demonstrator in light of the recent unveilment of the 2nd prototype ie. to prove a technology you shouldn't need 2 aircraft.
A mix of the two is also possible.

We don't know how agile the plane is yet. It may be agile enough to fulfil the fighter role.

 

[stardave]

Looking from the air frame design, J-20 is definitely a good dog fighter, better than F-22 and Pak-FA. Canard and big wing will give it excellent control at lower speed and angle of attack.

J-20: Flight Testing! - YouTube

I think this plane will be multi-role platform, from anti air to anti ground. But the most useful role is to launch air to sea attack missiles over the pacific, however the biggest problem with that is that currently China does not have any long range anti ship missile that can fit inside the J-20's weapon bay. Such as this one Naval Strike Missile - Wikipedia, the free encyclopedia 200+ km range and as short as AAM.

So that means they either have to develop a antiship missile that have 150+ km range and can fit inside the weapon bay, or it will perform role of combat air patrol over the ocean. It has enough fuel for sure.

 

[stardave]

As for the canard, yes it is very un-stealthy, however that can be changed if the canard does not move or move very little during flight. I am sure we all see photo that J-20's canard can almost move up and down by as much as 90 degrees. So that means if the jet is making a turn using canard it will show up as a blib on the radar, then it will disappear because the canard has return to the original position.

But I think it should be easy enough to write a software the restrict the canard's movement as little as possible during normal flight, because the plan can easily turn on it is own using ruder and flaps. That way, the canard will stay flat at 180 degrees with +- 10 degree of movements max.

And when the J-20 gets in close range combat, the canard will be able to allow to freely move again.

This is very possible, because remember, this is all being done with fly by wire. The pilot tells the jet where to turn and the jet move it is control surface automatically calculated by computers. That means there can be a mode in which it restrict the canard's movement to as little as 10 degree of movements during normal flight.

I know for sure Typhoon has some kind of software that uses to control of its canards in order to reduce its radar cross section. I don't know what it is, but it is probably this.

 

[Audio]

Looking from the air frame design, J-20 is definitely a good dog fighter, better than F-22 and Pak-FA.

How does an RC plane video you posted help in establishing that?

In my opinion it's just a bit too big to be a proper fighter or maybe it is just me having problems imagining something as big and heavy looking can turn on a dime.

 

[stardave]

How does an RC plane video you posted help in establishing that?

In my opinion it's just a bit too big to be a proper fighter or maybe it is just me having problems imagining something as big and heavy looking can turn on a dime.

Well, at least the RC plane has some evidence base in real physics, but your opinion is just your opinion.

 

[amalakas]

Well, at least the RC plane has some evidence base in real physics, but your opinion is just your opinion.

And there is a video by the (same?) people who have a model of the pak fa. Even more spectacular.

Rc planes made from derpon have no weight. that is the big difference here.

 

[stardave]

J-20 VS T-50 - YouTube I don't think they said pak fa. Even more spectacular.

J-20's layout is extremely maneuverable, the only reason it would not be maneuverable is if the engine is underpowered, when that happens the jet will have no energy to turn, kinda like Taiwan's IDF.

 

[amalakas]

J-20 VS T-50 - YouTube I don't think they said pak fa. Even more spectacular.

J-20's layout is extremely maneuverable, the only reason it would not be maneuverable is if the engine is underpowered, when that happens the jet will have no energy to turn, kinda like Taiwan's IDF.

RC models are not the same. the pak fa model has a single thruster, the J-20 two , and the point made in the video from the RC model is that the T-50 model is unstable. If you know what is what you know what that means. On the other hand the rc model of the j-20 is stable. Stable is NOT what you are looking for in a modern air design.

 

[stardave]

Yes I understand RC model is NOT the real thing, however aerodynamic speaking, it still shares many of the law of physics with the real world, because you can also build a RC 747 and they won't be as agile as a F-16, because even if it is smaller and lighter it still have to follow the law of air friction and newton.

And what do you mean stable is NOT what you are looking or in a modern air design? The ability to make quick turns and sustain high alpha is indeed extremely important in a modern air design.

 

[applesauce]

Seriously, we're basing discussions based on models made by a nobody that obviously didn't even attempt to make the models remotely similar to the real thing?

for the record, you can make just about anything fly with enough power(and/or light enough materials)

for instance:

a company that does this : FlyingThingZ – Cut Up the Sky!

now try to power them with jet engines and fly it at mach 1.5 and see how stable they are