PLA next/6th generation fighter thread

[sheogorath]

these guys are a little on the alarm now because they are concerned they will get in trouble.

I'd caution you guys from just posting too much from their individual tweet and Weibo that are cryptic and just fucking wait a few days.

They are clearly a little unnerved, so their comments are getting more cryptic.


Again, if this is really 3 engine + side-by-side seating, then what they are building here is more than just your usual fighter jet. It likely won't be procured in large numbers. It will have the role of directing and acting as central node for many UCAVs and other assets. But let's wait a few more days. Doesn't seem like we have to wait too long.

What are the chances of it also being an interceptor?. After Ukraine, it seems the concept is useful still, large, fast platform with massive radar/EW suite and LRAAMs with the added benefit that it's size can also perform strike mission. On top of it's drone control role, I mean.

 

[Engineer]

Three engines? I see only one possibility.

 

[Biscuits]

What are the chances of it also being an interceptor?. After Ukraine, it seems the concept is useful still, large, fast platform with massive radar/EW suite and LRAAMs with the added benefit that it's size can also perform strike mission. On top of it's drone control role, I mean.

That's my personal guess as well. Leakers seem to believe it is a "landmark" (I.e. something that once built gives you massive advantages against anyone not having it). A stealthy interceptor going at least F-111 speeds fits the mark of a silver bullet even against US and Russian airforces.

It will essentially be a B-21 without the subsonic drawback. As B-21 is arguably already nearing what can be called a 5.5 gen aircraft, the added speed and whatever other surprises it has will define it as 6th generation.

 

[talonn]

It it turns out to be fighter-bomber, will it make H-20 redundant? Or do they compliment each other?

 

[GTI]

Three engines might be a turbo-electric generator and electric jet engine similar to

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.

I think you might be on to something here, this could very well be it. I’ve actually not come across this in detail before. It’s a very simple and elegant solution.

If it indeed turns out to have 3 “engines” - I’m throwing my hat in the ring that this is the reason.

The turbo generator would be the middle “engine”, providing electric power to spin engines 1 and 3 in turbofan mode (and maybe producing some tiny thrust itself?). For the jet cycle it would continue to provide power but with fuel now pumped into combustors of engines 1 and 3.

Engines 1 and 3 only need to be uprated and then heavily modified WS-15s with the electric motors added. But none of this is actually bleeding edge technology and materials science.

 

[tphuang]

keep in mind of the power requirements of 6th gen.

F-35 right now is having a hard time because they are trying to future proof the demand by increasing thermal management to 80kw.

The major consumption of power on an aircraft is the radar.

Here is APG-79 for super hornet



This uses GaA T/R modules and it already requires 15kW of power requirement so liquid cooling needs to be 15.6kW. Since APG-81 is from the same generation and uses GaA T/R modules also, it's probably at this mark or a little more just for the radar. I would assume there is some more consumption from computers and processors, communication gears, powering of EW pods, EODAS and such, but the maximum usage is the radar. One could see how they got to the current requirement of 30kW max of cooling and want to increase it to 80kW

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1600 T/R module at 16kW would be 10 watt per T/R module, that I would imagine is the maximum possible for GaA modules from back in 2000s.

But nowadays, we are using GaN-on-Si, which should be at least several times that of GaA. In the future, we need to get ready for GaN on Diamond (or GaN-on-Sic if you are less ambitious)

Just a cursory glance on google search, you will find a GaN T/R module can have peak 100W power.

If you plaster 3000 T/R module. That would be capable of using 300kW of power.


Another look here, you can see the thermal conductivity of GaA is just 0.46 vs 1.3 on GaN vs 22 for diamond.

melting point is also much lower in GaA vs GaN vs Diamond.

There is a reason why GaA is only used for mobile phone power amplifiers now. The 5G cell towers all use GaN.

Remember from this

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Guobo has capacity for at least 20 million GaN chips and packaging for cell tower. You need more power on your cell tower, so you have to use a material that's capable of handling more power. That would be GaN, not GaA

Notice SiC's thermal conductivity is 3.5 and Si is 1.5? That's why GaN-on-SiC has better performance than GaN-On-Si

Macom was awarded money by DoD from CHIPS act for GaN-on-Sic.

GaN on Si has demonstrated minimally 8X the raw power density of incumbent GaAs technology while boosting efficiency to as much as 70%

So, if GaN-on-Si is at 8x GaA and GaN-on-Sic is 2x of Si and GaN-on-Diamond is 3x of Si.

Then, it would reason that 3000 T/R module GaN-on-Diamond may emit something close to 1MW in power.

I think all the computation power is probably going to be at most 10% of that. Even 8 Ascend-910B GPUs + 16 CPUs @ 300W each would be at most 7.5kW. Not in the same ball park.

Thermal management system needs to be able to handle 1MW in cooling requirement if you want to use the most powerful ever radar. Which is GaN-on-Diamond.

So peak power consumption requirement might be higher than 1MW!

so how much thrust is needed to support that much power generation?

Now, let's say you have nice battery and electric generator technology that is highly efficient and can shave peaks of your demand and that you only need to sustain 800kW power

LM-2500+ at 5.25t can generate 35MW of power

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A modern large turbofan of 1.7t (around WS-10C/WS-15 weight?) should be able to generate 10-15MW of power if that's all it did. As such, it doesn't really need to divert that much of its thrust to power the electrical stuff.

So, the key is still to have enough space for the plumbing needed to cool all that power generation from RF coming out of the aircraft.

 

[TK3600]

Until you know what the design requirements are, this is a strange assumption to be making.

nobody knows if 3 engines is a good thing or not because none of us know what the future air combat looks like. If they do end up using 3 engines, that is more revealing of what they think the future air combat looks like rather than anything else. Or even possibly this just indicates they intend to procure much much fewer of J-XD compared to J-20.

plaaf could entirely get it wrong here by ordering a fighter jet that is too large. We just don’t know.

and usaf may end up picking a design that shows entirely different goals.

You are making this all about engine when it should be a question of how large the aircraft is and how that fits into their overall plan.

I think we are being too prejudiced. We think engine is this giant tube that weigh much of the aircraft. But what if the third engine is a much smaller auxilory engine? One that has a specialized role that do not need constant operation that 2 main engine do? Perhaps it is for certain altitude? Or burst of high speed?

 

[Nx4eu]

Weirdly what I'm really interested in is the intake configuration. All the possibilities, and I think it's one of the more important details imo.

 

[sevrent]

keep in mind of the power requirements of 6th gen.

F-35 right now is having a hard time because they are trying to future proof the demand by increasing thermal management to 80kw.

The major consumption of power on an aircraft is the radar.

Here is APG-79 for super hornet

View attachment 140871

This uses GaA T/R modules and it already requires 15kW of power requirement so liquid cooling needs to be 15.6kW. Since APG-81 is from the same generation and uses GaA T/R modules also, it's probably at this mark or a little more just for the radar. I would assume there is some more consumption from computers and processors, communication gears, powering of EW pods, EODAS and such, but the maximum usage is the radar. One could see how they got to the current requirement of 30kW max of cooling and want to increase it to 80kW

Please, Log in or Register to view URLs content!

1600 T/R module at 16kW would be 10 watt per T/R module, that I would imagine is the maximum possible for GaA modules from back in 2000s.

But nowadays, we are using GaN-on-Si, which should be at least several times that of GaA. In the future, we need to get ready for GaN on Diamond (or GaN-on-Sic if you are less ambitious)

Just a cursory glance on google search, you will find a GaN T/R module can have peak 100W power.

If you plaster 3000 T/R module. That would be capable of using 300kW of power.

View attachment 140872
Another look here, you can see the thermal conductivity of GaA is just 0.46 vs 1.3 on GaN vs 22 for diamond.

melting point is also much lower in GaA vs GaN vs Diamond.

There is a reason why GaA is only used for mobile phone power amplifiers now. The 5G cell towers all use GaN.

Remember from this

Please, Log in or Register to view URLs content!

Guobo has capacity for at least 20 million GaN chips and packaging for cell tower. You need more power on your cell tower, so you have to use a material that's capable of handling more power. That would be GaN, not GaA

Notice SiC's thermal conductivity is 3.5 and Si is 1.5? That's why GaN-on-SiC has better performance than GaN-On-Si

Macom was awarded money by DoD from CHIPS act for GaN-on-Sic.



So, if GaN-on-Si is at 8x GaA and GaN-on-Sic is 2x of Si and GaN-on-Diamond is 3x of Si.

Then, it would reason that 3000 T/R module GaN-on-Diamond may emit something close to 1MW in power.

I think all the computation power is probably going to be at most 10% of that. Even 8 Ascend-910B GPUs + 16 CPUs @ 300W each would be at most 7.5kW. Not in the same ball park.

Thermal management system needs to be able to handle 1MW in cooling requirement if you want to use the most powerful ever radar. Which is GaN-on-Diamond.

So peak power consumption requirement might be higher than 1MW!

so how much thrust is needed to support that much power generation?

Now, let's say you have nice battery and electric generator technology that is highly efficient and can shave peaks of your demand and that you only need to sustain 800kW power

LM-2500+ at 5.25t can generate 35MW of power

Please, Log in or Register to view URLs content!

A modern large turbofan of 1.7t (around WS-10C/WS-15 weight?) should be able to generate 10-15MW of power if that's all it did. As such, it doesn't really need to divert that much of its thrust to power the electrical stuff.

So, the key is still to have enough space for the plumbing needed to cool all that power generation from RF coming out of the aircraft.

This is even more interesting given that USAF also sees 1MW power generation and cooling as a benchmark for its own future fighter as well.

 

[Temstar]

I'm seeing in multiple instances of weibo discussion under 6th gen fighter it's mentioned both CAC and SAC are doing competing designs. CAC is faster and their prototype is about to fly hence all the excitement. SAC isn't too far behind and their prototype is due to fly sometime next year.

Is this where all these J-XD1 and J-XD2 discussions are coming from?