Chengdu next gen combat aircraft (?J-36) thread

tphuang

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I dont think aircraft can be equated with EV's in this respect. Also what i mean with cooling demand is What kind of cooling capacity you need to cool the aircraft not the amount of power required by the cooling. So you cant really put it in power consumption there.

Let's say you want a DEW laser say 250 KW even with 50% efficiency you have at least 125 KW of waste heat, this needs to go somewhere, especially not to cause increase in IR Signature of the airframe.

Radar, say your MW level power plant can allow 100 KW of prime power to Radar, typical prime to radiated power efficiency is about 25% or maybe 35%. Only 35 KW of average power is radiated, leaving you with 65 KW of waste heat

ECM's you need a wide bandwidth amplifier for this, and for solid state, this tend to lower PAE (Power Added Efficiency) so no more 25-35%, it can even be as low as 20 or even 10% if you want coverage to say X-band to L-band. You let another 100 KW for the jammer thus about 10-20 KW of power with 90-80 KW of waste heat.

That makes some 370 KW of cooling demand here. For stealth it will most likely be going to fuel as heat buffer.
You are all over the place here.
My point is that you are not factoring in the advancement made by China in cooling technology of electrical platforms. There is a lot of R&D ensuring that electric motor, batteries, charging, RF base stations, AI data centers don’t overheat. I am not going to debate you further on what the size needs to be. If you believe it’s that large, it’s not worth my effort to argue this with you.

as for your other point, my comment about 1MW power consumption is about what the aircraft needs. The actual subsystems that use them may very well be just 50% efficient. That’s not relevant to what I’m saying since I never said the laser or radar are fully utilizing the energy going into platform.
 

FairAndUnbiased

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You are all over the place here.
My point is that you are not factoring in the advancement made by China in cooling technology of electrical platforms. There is a lot of R&D ensuring that electric motor, batteries, charging, RF base stations, AI data centers don’t overheat. I am not going to debate you further on what the size needs to be. If you believe it’s that large, it’s not worth my effort to argue this with you.

as for your other point, my comment about 1MW power consumption is about what the aircraft needs. The actual subsystems that use them may very well be just 50% efficient. That’s not relevant to what I’m saying since I never said the laser or radar are fully utilizing the energy going into platform.
no he has a point, the cooling is a legitimate problem. we have to consider the thermodynamics.

Your example of BYD Yangwang is not comparable. The quoted 1 MW power is not average power, it is peak power. Its storage capability of 80 kW-h of power is 288 MJ, which can only sustain 1 MW for 288 seconds.

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So are you talking 1 MW sustained electrical power, or peak power? If you are talking peak power, then maybe that can be achieved by emptying storage ie capacitors or battery. But if you are talking sustained power, then sustained cooling matters. And whether it is sustained power or peak power depends on the application.
 

Stealthflanker

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Laser is a bad example since it is not turned on 24x7. Most likely you fire up the laser for half a second then wait a few seconds to have a chance to fire it again.

because that's the thing might need the kind of power generation in Megawatt range, the DEW's.

You can put that into say AESA.. but Radar Range Equation clearly dictates gain from power increase is not as high compared to say increase in TRM.. say 20% for 2x increase in power. Electronics heat is tbh not as high. 80-90% of power load of an AESA is for the Antenna while the rest 10-20% is the electronics. Electronics may heat up but if you're talking about which likely saps more power and make more heat It's AESA or the DEW like Lasers, HPM or even jammers.

The other contributor is perhaps electro-mechanical/hydraulic actuators for surfaces
 

tphuang

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no he has a point, the cooling is a legitimate problem. we have to consider the thermodynamics.

Your example of BYD Yangwang is not comparable. The quoted 1 MW power is not average power, it is peak power. Its storage capability of 80 kW-h of power is 288 MJ, which can only sustain 1 MW for 288 seconds.
Let’s use U7 as an example, it has shown in testing. It can sustain 1MW power for 4 minutes. Do you think it needs to handle cooling for that or not?

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Given that I am the NEV guy, why are you giving me U9 wiki link?

So are you talking 1 MW sustained electrical power, or peak power? If you are talking peak power, then maybe that can be achieved by emptying storage ie capacitors or battery. But if you are talking sustained power, then sustained cooling matters. And whether it is sustained power or peak power depends on the application.
U7 is 3 ton and it can handle sustained cooling needs of 1MW power for 4 minutes.

J-36 is 60t. It will probably need to sustain 1MW power for longer than 4 minutes. But it’s also a whole lot larger. It can fit in a larger cooling system than U7 without it taking 600KG.

I do not know what that number is. But it’s fair to say that china’s supply chain has made significant progress in thermal management and high voltage system that the cooling system will be significantly smaller than what it required 10 years ago.

if you want to argue that China has made no progress in thermal management and cooling system since the start of its EV revolution, then I don’t see any reason to continue this exchange.
 

latenlazy

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Let’s use U7 as an example, it has shown in testing. It can sustain 1MW power for 4 minutes. Do you think it needs to handle cooling for that or not?


Given that I am the NEV guy, why are you giving me U9 wiki link?


U7 is 3 ton and it can handle sustained cooling needs of 1MW power for 4 minutes.

J-36 is 60t. It will probably need to sustain 1MW power for longer than 4 minutes. But it’s also a whole lot larger. It can fit in a larger cooling system than U7 without it taking 600KG.

I do not know what that number is. But it’s fair to say that china’s supply chain has made significant progress in thermal management and high voltage system that the cooling system will be significantly smaller than what it required 10 years ago.

if you want to argue that China has made no progress in thermal management and cooling system since the start of its EV revolution, then I don’t see any reason to continue this exchange.
no he has a point, the cooling is a legitimate problem. we have to consider the thermodynamics.

Your example of BYD Yangwang is not comparable. The quoted 1 MW power is not average power, it is peak power. Its storage capability of 80 kW-h of power is 288 MJ, which can only sustain 1 MW for 288 seconds.

Please, Log in or Register to view URLs content!

So are you talking 1 MW sustained electrical power, or peak power? If you are talking peak power, then maybe that can be achieved by emptying storage ie capacitors or battery. But if you are talking sustained power, then sustained cooling matters. And whether it is sustained power or peak power depends on the application.
So on the heat management question, a big factor for a plane is going to be how much heat you can dump into the engines, since the engines themselves are basically giant heat dumps (you’re literally expelling heat as reaction mass). The amount of bypass air generated by the engines should also play a large factor in how much heat dumping capacity the engines can provide. And I’m reasonably confident that this is another reason for having 3 engines. (If/when the powerplant move to VCEs their higher bypass should also help with this).
 

bsdnf

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It's crazy how automotive industry only took 1.5 years to upgrade from 400V to 800V architecture as the standard for mid-range and above NEVs, and there is a trend of continued penetration downward, bringing huge mass-production of high-voltage electrical parts and semiconductors. Guancha's latest broadcast also compared the J-36 to a new energy vehicle to explain the energy and engine design. When more details of the J-36 are announced, we will probably find that it is like NEV, using a fully electrified design to output ultra-high power to complete functions that were previously difficult to achieve.
Let’s use U7 as an example, it has shown in testing. It can sustain 1MW power for 4 minutes. Do you think it needs to handle cooling for that or not?


Given that I am the NEV guy, why are you giving me U9 wiki link?


U7 is 3 ton and it can handle sustained cooling needs of 1MW power for 4 minutes.

J-36 is 60t. It will probably need to sustain 1MW power for longer than 4 minutes. But it’s also a whole lot larger. It can fit in a larger cooling system than U7 without it taking 600KG.

I do not know what that number is. But it’s fair to say that china’s supply chain has made significant progress in thermal management and high voltage system that the cooling system will be significantly smaller than what it required 10 years ago.

if you want to argue that China has made no progress in thermal management and cooling system since the start of its EV revolution, then I don’t see any reason to continue this exchange.
 
Last edited:

antwerpery

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Another important thing about the J36 and the Shenyang 6th gen plane is just how fast their developmental process is. For a country that has historically struggled with high end aviation and whom has finished developing their two 5th gen programs recently, this kind of speed is unprecedented. It really goes to show just how mature China's aerospace institutions are and how much they have caught up to America. This is an example of how efficient Chinese R&D and engineering and how integrated the Chinese manufacturing base is. Most importantly, this is a good sign of how much of an improvement changes in China's developmental workflow, digitization and computational modeling brings to the table.

This will likely reflect how other R&D in other projects and fields will go. Future projects like new engines, type 004, the next generation destroyers, new drones, new tanks, submarines, even commercial projects like the C929/C939 etc etc, will likely have their development go smoothly and fast, without the development issues and delays that have plagued certain Chinese projects in the last two decades.
 

tphuang

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So on the heat management question, a big factor for a plane is going to be how much heat you can dump into the engines, since the engines themselves are basically giant heat dumps (you’re literally expelling heat as reaction mass). The amount of bypass air generated by the engines should also play a large factor in how much heat dumping capacity the engines can provide. And I’m reasonably confident that this is another reason for having 3 engines. (If/when the powerplant move to VCEs their higher bypass should also help with this).
Yes and I think on the podcast, they specifically mentioned that power generation and management as a key part of engine design choice for J-36. That it’s no longer about just getting the highest thrust.

it was a very interesting podcast. Using REEV tech for all military platform is an ongoing theme for PLA. They specifically talked about electrification of military platforms on that podcast. They talked about existing platform being inefficient. I can only imagine that putting something like a 100kWh battery pack in there (500kg probably) would make this far more efficient process to balance out peak power demand.

it’s probably too late for WS-15 to do this, but next generation engine can incorporate what we discussed before where you directly generate electricity to provide the power needed to spin the turbine rather than continuing with mechanical approach which is just less efficient.
 

FairAndUnbiased

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Let’s use U7 as an example, it has shown in testing. It can sustain 1MW power for 4 minutes. Do you think it needs to handle cooling for that or not?


Given that I am the NEV guy, why are you giving me U9 wiki link?


U7 is 3 ton and it can handle sustained cooling needs of 1MW power for 4 minutes.

J-36 is 60t. It will probably need to sustain 1MW power for longer than 4 minutes. But it’s also a whole lot larger. It can fit in a larger cooling system than U7 without it taking 600KG.

I do not know what that number is. But it’s fair to say that china’s supply chain has made significant progress in thermal management and high voltage system that the cooling system will be significantly smaller than what it required 10 years ago.

if you want to argue that China has made no progress in thermal management and cooling system since the start of its EV revolution, then I don’t see any reason to continue this exchange.
a fundamental difference is an EV does not use a heat engine. a battery is not a heat engine. the output of the motor goes mostly to the motion of the wheels, not accounting for small losses in transmission.

however, all energy on a plane, including the generator, derives from the engines. jet engines are heat engines and subject to thermodynamic efficiency. The generator is powered from a heat engine. Thus, 1 MW worth of sustained electricity being generated also means on the order of ~1 MW of sustained heat being dumped too.

I only link to give everyone else the numbers as a reference. Since you seem to think that's unnecessary, I'll not do it. easier for me anyways.
 
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