J-20 5th Gen Fighter Thread V

[antiterror13]

F-22 canopy looks bigger with better visibility. Radar on the J-20 appears bigger. F-22 crams 1956 T/R modules into that tiny nose .

so how many T/R modules on J-20 ?

 

[Hyperwarp]

so how many T/R modules on J-20 ?

Not sure. I have heard 1856 to 2200+. 1856 T/R modules seems to be the initially accepted value. Off-course Processing power has changed a lot since AN/APG-77 days. For example F-22 uses

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CPUs.

If PLAAF/Chengdu play their cards right, they should have a significant upper hand is sheer processing power. Whether they will use it effectively is another matter.

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[latenlazy]

Packaging size is another factor. A bigger radome may not mean a more powerful radar.

 

[Blitzo]

Packaging size is another factor. A bigger radome may not mean a more powerful radar.

Packaging, processing, cooling, will all influence the peak power that could be attained...
I think the comparisons between J-20's larger radome potentially meaning a more powerful radar compared to F-22 is assuming that factors above (and others) are at least equal in J-20's radar. I think the first APG-77 was delivered for integration in 1998, whereas the first J-20 radar probably would've finished development about 2012. Who knows where J-20's radar stands in comparison to APG-77 when it first emerged.

 

[antiterror13]

Packaging size is another factor. A bigger radome may not mean a more powerful radar.

if everything else the same, we can safely say the bigger means more powerful radar

I don't think current Chinese CPU is worse than the 1995 American CPU

Remember Chinese still hold the most powerful supercomputer in the last 3-4 years (TIANHE-2) with Linpack Performance (Rmax) 33,862.7 TFlop/s

And all Chinese Supercomputer ranks 14 in Nov 2011 (Sunway Blue Light) and rank 103 in Nov 2015

Sunway has Linpack Performance (Rmax) 795.9 TFlop/s and the best supercomputer in 1995 was Numerical Wind Tunnel with Linpack Performance (Rmax) 0.17 TFlop/s

 

[Brumby]

if everything else the same, we can safely say the bigger means more powerful radar

I don't think current Chinese CPU is worse than the 1995 American CPU

It doesn't work this way in radar technology.

so how many T/R modules on J-20 ?

There are three things that determine the number of T/R modules. Firstly, the physical size of the aperture is obvious in that the more space available the more modules that can be packed. Secondly is the available packaging technology that enables an optimal density corresponding to the third determinant i.e. targeted frequency. All fighter planes with radar essentially operates in the "X" band which has a frequency range but for simplicity say it is 10 GHz. This translates to a 3 cm wavelength. The rule of thumb for T/R spacing is half a wavelength apart which gives a 90 degree FOV without any grating lobes.

P.S. Mod. This should probably move to Chinese radar thread.

 

[Hyperwarp]

Lots of processing power alone is certainly not enough. After all, no point having Core-i7 6700K if the software sucks. I heard many rumors that the KJ-2000s computing power is well above the rest of the world but initially the Radar was more susceptible certain types of jamming compared to the western counterparts. I think this was disclosed by the chief designer himself during a documentary. So the computing power is just one aspect. So like I said before, if PLAAF+CAC play their cards right, they should have a very formidable system.

 

[antiterror13]

Lots of processing power alone is certainly not enough. After all, no point having Core-i7 6700K if the software sucks. I heard many rumors that the KJ-2000s computing power is well above the rest of the world but initially the Radar was more susceptible certain types of jamming compared to the western counterparts. I think this was disclosed by the chief designer himself during a documentary. So the computing power is just one aspect. So like I said before, if PLAAF+CAC play their cards right, they should have a very formidable system.

who said "computing power" is the only factor? not me

I don't disagree with all you said, but computing power is one of the most important factors

 

[latenlazy]

if everything else the same, we can safely say the bigger means more powerful radar

I don't think current Chinese CPU is worse than the 1995 American CPU

Remember Chinese still hold the most powerful supercomputer in the last 3-4 years (TIANHE-2) with Linpack Performance (Rmax) 33,862.7 TFlop/s

And all Chinese Supercomputer ranks 14 in Nov 2011 (Sunway Blue Light) and rank 103 in Nov 2015

Sunway has Linpack Performance (Rmax) 795.9 TFlop/s and the best supercomputer in 1995 was Numerical Wind Tunnel with Linpack Performance (Rmax) 0.17 TFlop/s

A radar is not the same thing as a CPU.

 

[antiterror13]

A radar is not the same thing as a CPU.

Who said that radar = CPU ? not me

see my comment above