So basically i crafted myself a KFX C-107. This hopefully be close to what would be built, still however fidelity would be limited to resolution of the reference image available to me. It's not going to need paints,textures etc, as it's for RCS approximation purpose. Then like many others i throw it to POFACETS. Set frequency to 10 GHz (X-band).
The Frontal aspect RCS appears to be quite promising (Perhaps it would be bit higher considering POFACETS actually underestimate curved surface RCS and it cannot do duct). The value in order of 0.1 sqm appears to be achievable in frontal aspect.
Also for additional interest i did another approximation this time to see the RCS fluctuation at frontal aspect.
One can see the fluctuation of RCS from frequency to frequency. It's quite jagged but show although kind of weak, dependence between wavelength and RCS. The POFACETS however or at least in my settings (PEC-no RAM) the increase or fluctuation caused by creeping and surface wave, this become important in lower frequency (where target feature is as large or smaller about half wavelength). But at high frequency regime where the feature of the target (e.g wing) is at least 10 times larger than impinging wave, it would be minor.
That however is just one of the caveat. The other is that POFACETS works for Specular RCS. Specular RCS is also known as "spike" It is the strongest RCS contributor, basically it is the "antenna mainlobe" of the feature being exposed to radar. Getting those spikes away from potential threat aspect is priority, so the enemy radar is presented with weaker lobes. However as the frequency decreased the power of the specular RCS decreases But the width of the "spike" increased.
Considering the limitation of the software i decided not to include the engine so the inlet and the exhaust is one big gaping hole basically. If i put anything inside there would be "unexplainable" spike arising from within the plane. Nonetheless I would love if anyone can point out on a "standard" on how RCS approximation can be done. Like everyone basically only "match" the size of the target with wavelength of the threat radar and maybe materials if the software supports. But none said on whether the inlet/exhaust should be blocked or can be left open so that the Resulted RCS graph is *only* from the external shaping of the target.
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