How is RCS computed? Like the F-22 is supposed to have 0.00001m2 RCS...

How is RCS computed? Like the F-22 is supposed to have 0.00001m2 RCS, Let's say there are 2 Chinese radar 200km from each other, and the F-22 passes between them, will both radars register it as 0.0000000001m2 from when it entered the radar airspace until it leaves (where it shows its engines to the radar)? Will the angle of the radar give any difference? Like a Chinese AESA is also patrolling the airspace between the radars and the F-22 flew past it from 80km away. Will the AESA looking down have any different register from the ground radars looking up or is it still 0.000000000001m2 from when it entered AESA airspace until the moment it left?

No Loneburg lens. No buying Chinese meme, just an example since the only other option is Russia and Russian radars are shit compared to China.

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Other urls found in this thread:

youtube.com/watch?v=7f7X6d1xtAg
radartutorial.eu/01.basics/The Radar Range Equation.en.html
twitter.com/NSFWRedditGif

Yes RCS changes according to the angle a radar looks at it from. This is why you'll hear things like 'optimized for frontal aspect'.

The only object where the rcs wouldn't change depending on the angle is a sphere.

So for the example of an F-22 passes by 2 mobile Chinese radars, does both radar register the plane at it's optimized value for frontal aspect when it is looking at the plane from below it so it's not really frontal but under?

Frontal aspect means the radar would be directly in front of the aircraft. That's the only time that number applies. All other angles are a higher value of cross section. So NO a radar directly below and one at 9 o'clock high will not read the signature value as the front optimized but some other value.

Is English your first language? You seem to be missing the meaning of alot of the words being used? If English is your first language what is the highest grade level of education you have obtained.

>HURRRRRR look how in-the-know I am guys
Shut up, you fucking cringelord.

My first language is Malay-Polynesian so excuse the incomprehensible babble. I hope the discussion stays with how stealth is used in real life scenarios and not how different one user's grammar is compared to the next one.

Basically there's not much different in the F-22 and J-20 stealth when they are used for their purposes?

FUCK YOU BITCH

You have a fundamental misunderstanding about what RCS is.

momentary bump while I type

Go be edgy somewhere else you retard, the guy just tries to learn something

Angle matters; the 0.0001m^2, etc values you see refer to the radar cross section (RCS) as viewed from the front but changes depending on angle. From directly above and directly below an F-22 the RCS could jump to something like 10m^2. Pic attached shows a Chinese simulation of an F-22 and F-35's RCS; it's not going to be super accurate, but it can give you a rough idea - up front (and take note that the F-22 is facing to the right in the image) the RCS is mostly small, then as you move towards the sides it gets much larger (the further the spikes are from the centre the larger the RCS). This is because at those angles the sides of your fuselage and your wings are starting to reflect radar energy. Towards the rear it generally starts to get smaller again; the Chinese simulation shows it getting even smaller than the frontal RCS because they don't account for RAM that's present up front but not present on the exhaust nozzles, etc.

If an F-22 flies between 2 radars (and assuming they're constantly looking in the F-22's direction) the RCS will initially be that frontal 0.0001m^2, then it'll rise and fall as the radars move (relative to the F-22) around the sides of the F-22's RCS pattern. As the F-22 gets between both radars its RCS will be at its highest, but then as it flies past it'll drop again.

RCS doesn't care if you have more than 1 radar operating independently; if you have multiple radars operating in a bi-static array then the RCS pattern changes based on where each radar is - if one radar is in front of the F-22 and another is roughly 80 degrees to the left of the F-22, then there'll be an increase in RCS where radar energy is bouncing (eg) off the wing leading edge (which is swept back at about 40 degrees) and going to the second radar on the left. It doesn't mean the 0.0001m^2 is eradicated, it just means that it may be something like 20 degrees either side of the nose instead.

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That's looking at things in 2D though; in this video, at about the 40 second mark you can see a 3D depiction of RCS. As you can see from the colours (where blue = low RCS, red = high RCS) the jet is stealthy from the front and rear, but essentially has a ring of high RCS going over the top and bottom of the jet, from wingtip to wingtip.

Pic is of a J-20 RCS simulation in 3D; again you can see that RCS is increased at the top, bottom and sides.

If an AESA is 80km away but at very high altitude, it's still only going to be a few degrees above the F-22 though, so if the AESA is in front or behind the F-22 it'll still see a very low RCS. If the AESA is looking down and the F-22 flies directly below it, then the AESA will definitely see the F-22.

Attached: Chengdu-J-20d-0015GHz-Rs0000-IncPol-TM-Pol-Theta--E=0450-A=2250-[1].png (1000x1000, 884K)

Forgot to link the video: youtube.com/watch?v=7f7X6d1xtAg

Also here's a pic of that spherical J-20 RCS rolled out and flattened; take note of the text / links saying "frontal aspect", etc; that shows you which parts are for the nose, tail, etc.

Attached: Chengdu-J-20d-0015GHz-Rs0000-IncPol-TM-Pol-Theta[1].png (1507x810, 1.59M)

Let's say a Japanese F-35B decides to visit the Spratly's Islands to deliver carrots. A Chinese AEGIS radar and an island radar spots something when it is about to cross/ go between them. How would they know what it is? How would they shoot it down? I mean can a missile get there before it falls off radar detection? Will an F-35B know it has been detected? Can an F-15 or J-11 follow a F-35B by following its engine RCS? Also how fast does a Chinese radar rotate so it has a better chance of detecting a plane when it is no longer in front of the radar?

>How would they know what it is?
They will see a mark, then they will dispatch a plane to check what is this. Point of stealth that this mark will be smaller than for a regular plane and from some distance it will be so small that it can't be recognized from general noise.
>How would they shoot it down?
Plane that was send to check the boogie status may perform interception. Or they can fire a missile. Some types of missile will fly to a signal reflected from a plane. In that case yes, F-35B will know that it is been targeted, because targeting signal for missile is very strong. Or missile can be launched into a projected place where F-35B should be and missile will use it's own radar to find it, then F-35B will know about the launch by optical system and later - by detecting a radar emission.
>Can an F-15 or J-11 follow a F-35B by following its engine RCS?
I think you're misunderstanding what is stealth.
radartutorial.eu/01.basics/The Radar Range Equation.en.html

>How would they know what it is?
If they can get enough consecutive returns to determine it's direction and altitude of flight, if they've mapped the F-35's RCS and if they have the software / hardware to support it, they could use inverse SAR mapping / RCS profiling to determine what it is. Alternatively they might be able to narrow down what it is based on emissions (say if the F-35 was transmitting some Link 16 data to a ship or whatever). If the F-35 is close enough and if the weather is permitting they might also be able to use EO/IR sensors to get a visual.

>How would they shoot it down?
Assuming they're at war in this scenario, they might fire a missile. It depends on how conclusively they can determine that they're looking at an F-35 (and not a MALD or an apparition created by EW or cyber warfare), and also how optimistic or desperate the SAM operators are. They might not know for sure that it's an F-35, but want to launch a SAM anyway. They might know that the target is likely going to drop off radar in a moment, but want to launch a SAM anyway. Syria for instance has launched dozens or hundreds of SAMs at targets they know they're unlikely to hit, just because it's their job and because once in a blue moon they'll get lucky and take out an F-16 that screws up.

>I mean can a missile get there before it falls off radar detection?
Depends on the range between the SAM and F-35, the radars being used, as well as the F-35's speed and classified RCS pattern. It also depends on how the SAM operates; if they rely on target illumination by the ground / naval radar then it'll likely fare worse than if the missile has its own seeker.

1/x

2/x
>Will an F-35B know it has been detected?
It generally will; when a SAM goes to fire it'll have a fire control radar paint the target either for illumination for the missile, and/or to try and maintain a constant track on the target for mid-course guidance. Essentially the F-35 will see a higher frequency radar focusing a (typically higher frequency too) beam on it.

>Can an F-15 or J-11 follow a F-35B by following its engine RCS?
If the jet can find itself at the F-35's 6'o'clock and at a short enough range, then yes, although an IRST might work better, and the ranges we're talking about the F-35 will almost certainly know you're following them. Also, while the F-35's exhaust isn't going to have a bunch of RAM, it is still fairly stealthy, so you might have better luck flying roughly alongside the F-35 and pointing your radar to the side to maintain a track of the F-35B (not all radars can scan 90 degrees to the side though; a fair few old mechanically scanned radars don't go past ~70 degrees, not all PESAs can mechanically tilt like the Su-35's Irbis-E and most AESAs are fixed in place, only scanning 60-70 degrees to either side.

>Also how fast does a Chinese radar rotate so it has a better chance of detecting a plane when it is no longer in front of the radar?
Depends entirely on the specific radar; a big VHF radar will rotate maybe once every 8 seconds, while something like a destroyer's SPY-1 equivalent doesn't rotate but instead can scan little sections of their field of view (anywhere in the field of view) a few hundred or thousand times per second. If you're asking how fast they should rotate / scan - the faster the better unless you know when the F-35 is going to be passing by.

stealth is a feature for fooling the American tax payer, nothing more.

Are you retarded?

Oh snap, someone is actually posting correct and helpful information.

Great work, sir, I concur on most all of your observations.

I don't even have a proper reaction image to express my feelings towards you right now. Have a lewd creepshot of a definitely-not-stealthy airplane instead.

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