J-20 5th Gen Fighter Thread VI

[ZeEa5KPul]

I've been thinking about something lately: since the WS-15 is not looking like it's going to enter service before the mid 2020's, how about redesigning/refining the J-20 air-frame in the meantime? It could always use a few touches - maybe revisit the necessity for ventral strakes given stronger engines, vectored thrust, more advanced flight control, etc.

J-20 v2; how feasible would that be?

 

[Blitzo]

I've been thinking about something lately: since the WS-15 is not looking like it's going to enter service before the mid 2020's, how about redesigning/refining the J-20 air-frame in the meantime? It could always use a few touches - maybe revisit the necessity for ventral strakes given stronger engines, vectored thrust, more advanced flight control, etc.

J-20 v2; how feasible would that be?

I think J-20 with WS-15 will be the "J-20 v2".


Right now it would be of greater interest to produce as many J-20s as possible and get them to the brigades.
The time and effort spent to redesign and test a J-20 with questionable minor structural or aerodynamic benefits before WS-15 is even ready would probably be better spent to be invested in increasing J-20 procurement, operation and related logistics.

 

[Xizor]

I've been thinking about something lately: since the WS-15 is not looking like it's going to enter service before the mid 2020's, how about redesigning/refining the J-20 air-frame in the meantime? It could always use a few touches - maybe revisit the necessity for ventral strakes given stronger engines, vectored thrust, more advanced flight control, etc.

J-20 v2; how feasible would that be?

The Ventral strakes hide the engines from certain directions. I think Thrust vectoring for ws-15 is a given and the ventral strakes has been included with full knowledge and confidence of a ws-15 with TVC 3D. In short, I dont think they'd change the designs any further.
Improvements in stealth coating, AESA Radars, EOTS, EW etc are welcome.

 

[ZeEa5KPul]

I think J-20 with WS-15 will be the "J-20 v2".


Right now it would be of greater interest to produce as many J-20s as possible and get them to the brigades.
The time and effort spent to redesign and test a J-20 with questionable minor structural or aerodynamic benefits before WS-15 is even ready would probably be better spent to be invested in increasing J-20 procurement, operation and related logistics.

I was thinking about it happening concurrently. The current v1 would go to the brigades to counter the F-35s proliferating in the region - the v1 design is frozen so the J-20's original designers should have the time and resources to tweak the design a little, although that would probably mean pulling them from preliminary work on the 6th gen. But it shouldn't hamper procurement of the current version.

I bring this up because I hear time and again that the J-20's RCS shaping is fundamentally inferior to the F-22/F-35; that's likely just American posturing and propaganda, but it couldn't hurt to go over the design again with a circa 2020 supercomputer.

The Ventral strakes hide the engines from certain directions.

True. I notice that the J-20 sometimes aligns an edge with an edge on the opposite side of the fuselage. For instance, the strake is aligned with the tail on the opposite side (even the side of the cockpit is aligned), so clearly a lot of thought has been put into this.

Why the canard dihedral, though? Why not have it co-planar with the wing?

 

[Blitzo]

I was thinking about it happening concurrently. The current v1 would go to the brigades to counter the F-35s proliferating in the region - the v1 design is frozen so the J-20's original designers should have the time and resources to tweak the design a little, although that would probably mean pulling them from preliminary work on the 6th gen. But it shouldn't hamper procurement of the current version.

I bring this up because I hear time and again that the J-20's RCS shaping is fundamentally inferior to the F-22/F-35; that's likely just American posturing and propaganda, but it couldn't hurt to go over the design again with a circa 2020 supercomputer.

Money and human resources spent on redesigning J-20 and having to test it again means less money and human resources spent on 6th gen and/or a more thorough redesign of J-20 once WS-15 is mature IMO. The money in particular could be better spent simply buying more J-20s and/or investing it to expand production or make current production more efficient.

A negative affect on procurement may also occur when your proposed variant begins to enter production and they'll have to retool to build the new variant, and then have to change again when they start producing J-20s with WS-15s.



I fully expect improved variants of J-20 to be developed and produced in future, but I don't see why they wouldn't wait for such a variant to be developed once WS-15 emerges instead. I don't see why there would be a demand to rush out a variant that will likely only finish testing before WS-15 becomes ready anyhow.

 

[Air Force Brat]

I was thinking about it happening concurrently. The current v1 would go to the brigades to counter the F-35s proliferating in the region - the v1 design is frozen so the J-20's original designers should have the time and resources to tweak the design a little, although that would probably mean pulling them from preliminary work on the 6th gen. But it shouldn't hamper procurement of the current version.

I bring this up because I hear time and again that the J-20's RCS shaping is fundamentally inferior to the F-22/F-35; that's likely just American posturing and propaganda, but it couldn't hurt to go over the design again with a circa 2020 supercomputer.


True. I notice that the J-20 sometimes aligns an edge with an edge on the opposite side of the fuselage. For instance, the strake is aligned with the tail on the opposite side (even the side of the cockpit is aligned), so clearly a lot of thought has been put into this.

Why the canard dihedral, though? Why not have it co-planar with the wing?

Angled vertical stabilizer's and canards reduce RCS numbers by decreasing radar returns to the receiver.

 

[Blitzo]

Why the canard dihedral, though? Why not have it co-planar with the wing?

Because 611 are stupid.

.... or it provides some sort of benefit, and whatever adverse effect it may have for RCS (or what not), was considered a worthwhile trade off.

 

[Totoro]

Because it would otherwise defeat the purpose of having canards in the first place. To get meaningul benefits from canards they have to rearrange airflow so the canards are throwing the air over the wings. If their whole surface was at the same level as wings, they would not be able to fulfill their aerodynamic purpose.

 

[ZeEa5KPul]

A negative affect on procurement may also occur when your proposed variant begins to enter production and they'll have to retool to build the new variant, and then have to change again when they start producing J-20s with WS-15s.

The money issue you raise is sadly all too valid, especially given how miserly the Chinese government is with military funding. But I think you misunderstood me - the variant I have in mind isn't an intermediate between now and the WS-15; it's based around the WS-15 now that the performance parameters of the engine are clear (at least to the people who need to know them).

Because 611 are stupid.

.... or it provides some sort of benefit, and whatever adverse effect it may have for RCS (or what not), was considered a worthwhile trade off.

Ouch. We've interacted a few times over the years, and while I know you take issue with my bellicosity and polemic style I like to think you don't think me stupid. Of course I know the canards are like that for a reason; I'd like to understand what that reason is. By the way, I do think 611 is at least a little stupid to fly these planes without any treatment to the engine nozzles - no trade-offs there, just laziness.

I must say, I do like the snark. You should do it more often.

Because it would otherwise defeat the purpose of having canards in the first place. To get meaningul benefits from canards they have to rearrange airflow so the canards are throwing the air over the wings. If their whole surface was at the same level as wings, they would not be able to fulfill their aerodynamic purpose.

I'm perfectly willing to be corrected here, but I think this applies only to close-coupled canards like the J-10. That's not the J-20's configuration.

 

[Blitzo]

The money issue you raise is sadly all too valid, especially given how miserly the Chinese government is with military funding. But I think you misunderstood me - the variant I have in mind isn't an intermediate between now and the WS-15; it's based around the WS-15 now that the performance parameters of the engine are clear (at least to the people who need to know them).

Okay, if that's what you mean then I think developing a future variant once WS-15 is ready would make more sense.

However the way you phrased your original suggestion really made it sound like you were wanting this aircraft to emerge before WS-15 came out.

since the WS-15 is not looking like it's going to enter service before the mid 2020's, how about redesigning/refining the J-20 air-frame in the meantime?

Ouch. We've interacted a few times over the years, and while I know you take issue with my bellicosity and polemic style I like to think you don't think me stupid. Of course I know the canards are like that for a reason; I'd like to understand what that reason is. By the way, I do think 611 is at least a little stupid to fly these planes without any treatment to the engine nozzles - no trade-offs there, just laziness.

I must say, I do like the snark. You should do it more often.

Sorry, I'm joking somewhat but I become triggered when the topic begins to veer towards the "eyeballing of aerodynamics".
In terms of J-20's canards, I don't want to claim to know enough about aerodynamics to suggest what exact benefit their positioning provides, but there must be a reason why it is not perfectly in plane with the wing.
All aircraft (as with all engineering projects) are a mix of deliberate compromises, as I'm sure you appreciate.


As for J-20's engine nozzles, I think they are somewhat treated; they don't look like standard Al-31 family nozzles after all.