PLA next/6th generation fighter thread

[sheogorath]

I think things get interesting when you consider that a lot of the current research around sonic boom reduction and improved trans-sonic performance seems to revolve around tri-jet designs. Previous to that it was mostly relegated to early jet age bombers to compensante for the lack of engine power and passenger jets.

 

[Blitzo]

I might be coming into this discussion way too late and at the risk of the mods nuking me, one possible benefit for a 3-engine 6th Gen might be that China, whilst they have come a long way, still does somewhat lag when it comes to leading edge engine development. The PLAAF might not be confident in the industry to deliver a variable cycle engine in the timeframe that they want to start inducting 6th gens to the tactics development squadrons. Having 2 'performance' engines and one 'efficient' engine might be a way to get the jet to both fly very well with incredibly high efficiency over longer ranges (up to crossing most of the Pacific and back) whilst also mounting traditional high-performance jet engines to fight and maneuver well when it becomes necessary.

There are many reasons "why" a three engine configuration could make sense. I don't want to list them all, but they are mostly just permutations of "two engines insufficient thrust for airframe of the size/nature that they want".

The implication is buried a little bit -- but it would suggest they do not anticipate their engine technology to be sufficiently capable to meet the needs for a two engine design in the near future, and the deficit is so significant that the added weight of a whole other engine is seen as a better solution to their requirements, and it also implies they would likely be stuck with a three engine design as well (airframe redesign if they were able to one day have a suitable engine for a two engine design, would not be easy to do).

And if they were pursuing a three engine design with the goal of having two engines be say, lower bypass and one engine be say, higher bypass, to emulate the ability of variable cycle engines for different flight regimes, it's questionable whether they even have the suitable powerplants for that to occur let alone whether the added weight of a whole other engine is worth it either.


So yes, sure it's not non-viable for the J-XD to have three engines, but it would have such profound implications for everything about the industry and technology that they have available and where they anticipate themselves to be, and it would also be a major shift from what we expect for J-XD on the background of what little news we have had about it in the last year or so.
It would be exceptional for such a major deviation/design choice to only be revealed to us this late in the game, and so soon to its anticipated reveal.

 

[lcloo]

I just realised that the drawing was made by 草根设计师。 Judging from the past drawings of his, I would say his drawings are normally not accurate but not too far from the real thing. Some times he was way off, other times he was quite close, may be that was because he did had some information but not complete details.

Just wait for the first blur photo to show up, and then we can figure out whether it has 2 or 3 engines.

 

[leibowitz]

Might just be for sheer firepower

There are many reasons "why" a three engine configuration could make sense. I don't want to list them all, but they are mostly just permutations of "two engines insufficient thrust for airframe of the size/nature that they want".

The implication is buried a little bit -- but it would suggest they do not anticipate their engine technology to be sufficiently capable to meet the needs for a two engine design in the near future, and the deficit is so significant that the added weight of a whole other engine is seen as a better solution to their requirements, and it also implies they would likely be stuck with a three engine design as well (airframe redesign if they were able to one day have a suitable engine for a two engine design, would not be easy to do).

And if they were pursuing a three engine design with the goal of having two engines be say, lower bypass and one engine be say, higher bypass, to emulate the ability of variable cycle engines for different flight regimes, it's questionable whether they even have the suitable powerplants for that to occur let alone whether the added weight of a whole other engine is worth it either.


So yes, sure it's not non-viable for the J-XD to have three engines, but it would have such profound implications for everything about the industry and technology that they have available and where they anticipate themselves to be, and it would also be a major shift from what we expect for J-XD on the background of what little news we have had about it in the last year or so.
It would be exceptional for such a major deviation/design choice to only be revealed to us this late in the game, and so soon to its anticipated reveal.

3x WS15s would deliver enough thrust for 20 tons of fuel and 10 tons of weapons, in a 25 to 30 ton airframe. It would carry more ordnance than the B21...

 

[lcloo]

I have just visited 草根设计师-CAD's weibo. Below is one of his latest drawing on weapon bay of J20. I would say it is more like a wish-list rather than a real thing. It is possible but unlikely as we do not hear any rumour on such missile load configuration, nor new development of a new type of AAM smaller than PL-10.

I think we should disregard his 3 engine drawing for now.

These missiles look strange.

 

[David78]

I have just visited 草根设计师-CAD's weibo. Below is one of his latest drawing on weapon bay of J20. I would say it is more like a wish-list rather than a real thing. It is possible but unlikely as we do not hear any rumour on such missile load configuration, nor new development of a new type of AAM smaller than PL-10.

I think we should disregard his 3 engine drawing for now.

These missiles look strange.
View attachment 140236

No canards. Not a J-20.

 

[ZeEa5KPul]

I'm getting the feeling this person is having a laugh at our expense. If not and this hideous abomination is accurate, then all I can say is yuck.

There are many reasons "why" a three engine configuration could make sense. I don't want to list them all, but they are mostly just permutations of "two engines insufficient thrust for airframe of the size/nature that they want".

The implication is buried a little bit -- but it would suggest they do not anticipate their engine technology to be sufficiently capable to meet the needs for a two engine design in the near future, and the deficit is so significant that the added weight of a whole other engine is seen as a better solution to their requirements, and it also implies they would likely be stuck with a three engine design as well (airframe redesign if they were able to one day have a suitable engine for a two engine design, would not be easy to do).

It doesn't track with both how previous airframes were designed and the advances we know China's made in turbofans. The J-20 entered service a decade before its intended engines were ready, they just flew the airframe with underpowered engines and called it a day. There's no reason not to expect they wouldn't do the same here (the null hypothesis, as you like to say).

Low bypass turbofans are also a more or less solved problem - with the biggest problem being casting the parts in the high pressure turbine - and the differences between the best China and the US can make today are far smaller than they were when the J-20 was being designed. Also, the rumours we have indicate that the VCE program is proceeding well, so the conclusion that it's so significantly behind that the airframe had to be redesigned would be very surprising.

If it does have three engines (once again, yuck), then it's intended to have three engines with its intended engine from the start.

 

[Blitzo]

I'm getting the feeling this person is having a laugh at our expense. If not and this hideous abomination is accurate, then all I can say is yuck.

It doesn't track with both how previous airframes were designed and the advances we know China's made in turbofans. The J-20 entered service a decade before its intended engines were ready, they just flew the airframe with underpowered engines and called it a day. There's no reason not to expect they wouldn't do the same here (the null hypothesis, as you like to say).

Low bypass turbofans are also a more or less solved problem - with the biggest problem being casting the parts in the high pressure turbine - and the differences between the best China and the US can make today are far smaller than they were when the J-20 was being designed. Also, the rumours we have indicate that the VCE program is proceeding well.

If it does have three engines (once again, yuck), then it's intended to have three engines with its intended engine.

My overall view on the three engined idea is one of reserved skepticism (though not ruling it out of course), due to:
- three engines has significant implications on the aircraft's nature, as well as the tech stack in the industry (and expectations of it)
- three engines is such a deviation from the twin engine configuration we would expect (indeed, the null hypothesis), and it strikes me as very odd that if such a major design feature was true then we have heard nothing of it in the leadup to J-XD being revealed in the near term.

I have no particular view wrt "yuck" or "awesome" and I'm approaching this just from a dispassionate perspective of "what makes sense".

 

[Nx4eu]

I have just visited 草根设计师-CAD's weibo. Below is one of his latest drawing on weapon bay of J20. I would say it is more like a wish-list rather than a real thing. It is possible but unlikely as we do not hear any rumour on such missile load configuration, nor new development of a new type of AAM smaller than PL-10.

I think we should disregard his 3 engine drawing for now.

These missiles look strange.
View attachment 140236

Unrelated to the thread but i don't see anything strange
The largest missiles are clearly PL-17’s with folding fins
the medium missiles are PL-15’s with folding fins
and the smallest missiles are PL-10’s with folding fins.
Ofc the 17 and 10 are fictional, a fun what if drawing if you will.

And with David’s comment, I don’t believe that is exactly a J-20 bay as there are no canards, and the shape of the weapons bays are different, there are actually many differences. Perhaps his fictional vision of a what if for a J-20. I honestly don’t believe his 3 engine design is credible at all if he is a guy who likes drawing what if content and posts it around.

 

[ZeEa5KPul]

My overall view on the three engined idea is one of reserved skepticism (though not ruling it out of course), due to:
- three engines has significant implications on the aircraft's nature, as well as the tech stack in the industry (and expectations of it)
- three engines is such a deviation from the twin engine configuration we would expect (indeed, the null hypothesis), and it strikes me as very odd that if such a major design feature was true then we have heard nothing of it in the leadup to J-XD being revealed in the near term.

I have no particular view wrt "yuck" or "awesome" and I'm approaching this just from a dispassionate perspective of "what makes sense".

It's pretty weak evidence for the 3 engine case, but I wonder if this is what Yankee said when he called it "not good looking"

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