laws of science that say the radar waves bouncing on an object will travel back much slower

Wait…what? The speed of light slows down? Are you sure about that? Don’t say that too loud or scientists will be upset that you’re claiming the one true constant is actually a variable.

Annex F Additional Notes on Physical Optics RCS Modelling

That is basically information cut and pasted directly from the thesis of the guy who wrote the POFacets software.

Why would I need to provide similar when I’m using exactly the same software (except Kopp got one of his developer buddies to rewrite it in C++ to increase performance)

How exactly? Because i dont really get scale (50 cm and 10GHz? what frequency we need to compare with APA simulation). Its better you give a comparison figure in order to make this more convincing.

The 3d model used was a 50cm wide axial cross section of the underside of the engines, the model is shown on the image with the graphs. Its an RCS test of a shaping feature, not a whole aircraft, I thought that was pretty clear. RCS is all to do with angles, I was looking at areas where the angle of incidence of a threat radar with the surface is very low (ie, bad for RCS).

I believe APA’s analysis covered 8GHz and 12GHz? There is little difference between those and mine (all x-band) and mine demonstrates exactly the same 5 lobe pattern APA observed.

but APA’s result doesn’t give that much difference between j20 and t50

You’re either not looking at the right place or not understanding the implications of what you’re looking at with APA’s charts…

Beam aspect RCS at 8GHz

J-20

PAK FA

Example : the radar wave from F-35 go to rafale , it will bounces on the aircraft and come back , at the same time Spectra will analyze the signal and create false signal , send back to the F-35’s radar but no matter how fast is the computer on rafale it still need time to measure and create the signal , even if it only take 0.01 second ,the signal sent by Spectra still arrive to the F-35 radar slower than the real Apg-81 waves that bounces from the rafale airfame ( because they not start at the same time ), so the APG-81 will only reject the Spectra signal

All correct and something I don’t think he has the knowledge to comprehend. All his ranting showed was that he knew the names of a few high level jamming effects but not how they’re actually acheived.

If the Radar the rafale is jamming is running on a higher number of frequencies than the rafale’s aesa jammers is capable of matching with any useful signal density, then the rafale loses (eg. AEGIS, AN/TPY-2, any russian ground based AESA)

If the radar has a higher agility than the rafale’s jamming transmitters then the rafale loses. Jamming doesn’t do anything once the range gate has closed or the reflected pulse has returned.

The system may work on 50 year old libyan systems, but point a pair of late generation AESA’s at it and its a dead turkey. Nice big, rounded intakes, bad at all polarizations, plenty of little probes, balls and panels facing directly forward …. a christmas tree. Huge, radar mirror of a tail.

Yes, I do have source(s) and there are diminishing returns but they are marginal- the relationship remains proportional and not logarithmic so much so that you should consider 3x 3mm as a definite ‘worst case’ scenario for the said 1PP8M10-6.

Where is it?

wonder material

Speaking of wonder material that can be applied in as many layers as one needs to fix any shortcomings of shape. I might try a bit of that deductive reasoning myself.

So, if the PAK FA has a few shaping features which render its base RCS similar to a 4th gen fighter to ground radar at quite long range, why would Sukhoi want to develop a whole new aircraft when they could just apply numerous layers to a Su-35 and get the same result cheaper? I don’t get it.

When can we expect stealth Tu-22m’s?

wouldn’t your model have increased figures due to edge defraction at the edges of the section?

No, pofacets doesn’t calculate edge diffraction, which is handy for doing hemisphere simulations.

I also put the models in position so the top of the shape is absolutely not calculated.

The CNT-based signature control material 1PP8M10-6 (1ПП8М10-6) has a reflection coefficient (Коэффициент отражения, дБ) of -10dB for the radar frequencies (Радиодиапазон) of L-band (30cm) ranging to -30dB for mid Ka-band (1mm), with a material thickness (Толщина, мм) of 3mm!!

For the crucial X-band (8 to 12GHz), it must be at around -20dB, but if they double the thickness to a whopping 6mm that should be sufficient for the T-50’s RCS ‘hotspots’. Bearing in mind this is the vanilla version, the customised (radar frequency-specific) versions for the T-50’s will easily be under 10mm.

A 2008 Russian patent of a similar RAM details an absorption of 28.6dB (~95%) over the frequency range of 8-26GHz (X-K band), that material was 10mm thick.

Roll on “QuickStep” OOOOOORAAAAAAAAAHH!!!

Nice work finding actual values, but still, is it enough to compensate for the beam aspect shaping issues? The answer is “most likely not”, and shape is still paramount to stealth.

Below is an lower hemisphere RCS simulation of two 50cm axial coss sections including the problem child inner nacelle and the rear engine section with its poorly angled cylindrical outer surface. Both tests done at 10GHz and models are to scale.

The red areas signify where stealth is most important to remain hidden from radars at an operationally significant range.

Unfortunately, other stealth aircraft cross sections I simulated (F-22, F-35, J-20, J-31) using exactly the same conditions came back with an RCS -20 or -30 dBsm smaller.

With knowledge of this material’s capability I can now see how people can say the F-35 is all aspect stealth, but the PAK FA is still at risk of being tracked by radars out to around 190km for minutes at a time. I copped some stick for predicting it is a defensive, denial of access only fighter, but it’s looking more and more likely.

Before anyone says it (cookie for the first “genius” to complain about it), no, the inner surface join on the 3d shape is not exactly the same as the real deal, but that’s irrelavent as the outer surface is the problem.

Because it is French of course, can there really be any doubt?

:rolleyes:

Do they fall off the aircraft in surrender the moment the battle begins? ;D

Pierre Sprey also thinks the US should only have 100 aircraft total fitted with radar as the size tradeoffs for fitting them is not worth it 😀