Point being ,is that the many nationals of respective nations when promoting their aircraft see it as a shape or a combination of shapes. They then assume that this shape(or the combination of shapes) has a RCS that is done by adding 1+1+1=3.
When the reality is far from that as you have stated here countless times and discussed.
There was this whole discussion on turning conventional aircraft stealthy, all sorts of stealth pods, RAM coatings and so on where discussed but at the end no one bothered to think whether the weapons hanging off it will generate their own RCS based on the totality of their surface and the interactions it has with itself and the aircraft wings.
This is my favourite reference to that. This shot is taken from the National Geographic documentary on the Horten XIII and the team from Northrop Grumman (those that built the B-2 if some did not know) who remade the aircraft for a RCS test. This was the first time I suppose that one was able to see modern RCS modelling techniques. The model was bombarded with VHF,UHF and L Band to simulate those days of Radar, but the principles of EM apply the same.
The model went up on a pole and the results are below. The two images show how electromagnetic energy radiates across the aircraft as it is rotated against an emitter. Here at a side pose, the energy return is lower due to the position of the surface(s) of the aircraft.
One the aircraft is taken at full frontal exposure the energy return spikes around the areas that are reflecting the most energy.
Now there is on thing to notice, this sort of method gives us the advantage to see how exactly the energy spikes across a certain area. for e.g. you dont see a
red outline of the cockpit instruments with the stick and seat and everything, but a combined red blur that is the combination of electromagnetic energy being reflected back to the receiver.
What it tells you is that by fixing the seat of the aircraft the designers may reduce the intensity of the
red blur by a bit, but perhaps not by that much. If they do the same to the inlet, the reflected energy may dissipate but it wont do so if you just fix one area by applying RAM or otherwise. It has to be a combination of factors(compromises) to get the RCS of the red area down to say
orange or
dark yellow levels.
This is what @
gambit has been trying to say here, and I have also taken cues from him to say elsewhere. The RCS is not a single shape(s) or design idea but a combination of all these factors. Just putting weapons in a pod will not fix the aircraft nor will adding Canted tails.
Now lets come back to the J-20, I am sure that the J-20 went through a similar procedure. The designers of the J-20 might have(as we calculate a guess) seen similar red areas for the aircraft with the cockpit, the intakes and the Canards over a full 360 degree sweep. They would then start looking for design ideas(compromises) that reduced those red areas; they could coat the cockpit with RAM, they would change intake shape and coatings, the would design algorithms built into the FLCS that manages the Canards to change position to minimize its energy return and avoid red spikes in favour of yellow or light yellow ones. The same sort of compromises go into aircraft such as the F-22, F-35, PAK-FA .. and are a reference to all those trying to come up with ideas to reduce RCS of conventional aircraft such as the F-15(F-15SE) or the JF-17.
It is important to always look at something with an open mind and always look for the most technical explanations possible as long as it is not technical loghorroa( Diarrhoea of useless information).
If you still have your doubts, take a look at this. What if someone someday was able to get something like this to fly without the extra bits on the top.. a Sphere aircraft so to say? What do you think the RCS of this massive thing will be? You would be surprised that it will near the RCS of the B-2(or less if done properly).
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Dillinger @
Armstrong @
Aeronaut @
Bilal. @
Chak Bamu