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Su-57 RCS and general Stealth discussion

Dev

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anti ballistic missile look through narrow elevation? In what way?. Most aircraft cruise below 60.000 ft (18 km), at 350 km the elevation is about 3 degree, at 250 km, the elevation is 4.5 degrees, at 100 km, the elevation is still only barely 10 degrees. On the other hand, ballistic missiles can climb to 2000 km, which mean at 1000 km the elevation is already 63 degrees. Also, anti ballistic missile doesn't look through narrow sector, it is quite the contrary
Ballistic missiles have a static trajectory. Therefore, there is no need to scan at a wide angle (elevation angle). This also supports the smaller antenna height. By eye, the aspect ratio of TPU-2 is about 1: 3. With an effective area of 6 m2, we get sides of about 1.4 * 4.3. The solid angle is about 1 square degree at a wavelength of 0.03. Based on my experience, I know that the scanning sector of such radars in standby mode is 90 * 15. Scanning with such a beam will take 27 seconds. Which is quite acceptable for such radars.

Once again.
I'm tired. I showed you that two radars with the same scanning and energy properties, but different in wavelength (1.1 m and 0.03 m) will have different losses. This difference is 31 dB.
Do you agree with that?
And you were given figures and official source, you basically just quibbling
We walk in circles.
1. Chinese experts are not an official source, just like Ukrainian experts. The point is simple. You like the Chinese number, but not the Ukrainian one.
2. LM presentation, does not contain figures. The air defense loss graph cannot be compared with the RCS numbers.
3. The words of the LM representative do not contain figures, but only abstractions that can be interpreted as you like.
4. The article of the Air Force Major, has figures. But they were taken from a certain writer. Where did the writer get these figures- I don't know.
In addition, these figures do not agree with other sources for a small RCS. They claim that the RCS B-2 is less than the F-117.
Nope, it was P-18. I have the presentation given by Zoltan Dani himself
I will not argue about this. Although Anich in his book talks about the P-15. It is the P-15 that is attached to the S-125 divisions. The P-18 is assigned to the S-200 divisions.
But again, I agree with you so as not to give you a reason to cling to words.

And your so called "fact" is based on a guy speculating with his naked eye when he was attacked by a missile at night ;)
Understand, if the person was not sure, then he would have picked up a more general word. But he indicates exactly the value (figure).
At the same time, non-standard direction angles, such as 45, 90, etc. And clearly 50.

I thought you only believe official sources, all the journalist and non government sources are garbage?. Now you resort to use a badly photoshopped image from Instagram? The name of the Instagram account is literally still on your photo ;)
Let it be a poorly photoshopped picture. Like this one. :D
1610185361418.png
 

Dev

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I will now reveal the SECRET of American stealth aircraft.
I know that Have Blue was calculated for CRAY-1.
The transition from the faceted form F-117 to the more aerodynamic form of the F-22 is due to the increase in computing power in the mid-80s.
But you must admit that the last word is still for natural experiments. And it is impossible to judge RCS only by computer modeling.
 

Dev

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Colleagues, I apologize for the offtopic. Although the topic has long since departed from its name. I am not very familiar with the threads of this forum.
Prompt a stream of books.
I am intrigued by the books of David C. Aronstein
Have Blue and the F-117A: Evolution of the "Stealth Fighter"

and
Advanced Tactical Fighter to F-22 Raptor: Origins of the 21st Century Air Dominance Fighter
 

LMFS

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I will now reveal the SECRET of American stealth aircraft.

A computational electromagnetics model is used to predict the radar cross section of an object in software.
Models for which PTD was critical and PO simply insufficient...
 

Dev

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No, it is the same. For the chinese radar scattering simulation, I can at least see what their model look like. In the simulation cited by tequila, I can also see the model and the method they choosen for simulation which is without canopy and radome cone. In both case, there are radar scattering graph to see the distribution of lobes.
Well, experts from two Taiwanese institutes believe that the RCS of the F-22 from the nose, at a frequency of 2 GHz is 12 m2
1610193819847.png
I understand that you will now say that they are complete fools, because you will not like this figure. But they did the same as the Chinese specialists.

In case of the chart given by Wu Jian Qi, there is no number for the aircraft RCS, but there are comparative detection range and also the actual event where only the VHF radar detected the fighter and nothing else.
We have already found out that we do not know which radars he is comparing on his diagram. And to estimate the RCS from this picture is like looking for numbers in the LM presentation by the percentage of losses from air defense. There is nothing that one could catch on to get at least some numbers. There are not even indirect signs by which something could be determined
 

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Ballistic missiles have a static trajectory. Therefore, there is no need to scan at a wide angle (elevation angle). This also supports the smaller antenna height. By eye, the aspect ratio of TPU-2 is about 1: 3. With an effective area of 6 m2, we get sides of about 1.4 * 4.3. The solid angle is about 1 square degree at a wavelength of 0.03. . Scanning with such a beam will take 27 seconds. Which is quite acceptable for such radars.
Firstly, whether ballistic missile have static trajectory or not is irrelevant, you are searching to find them inside a volume of space, ballistic missiles can climb to much higher altitude so the elevation is higher. We are basically comparing between 2000 km in height vs about 18 km in height, you need much higher elevation to track ballistic missiles.
Secondly, the area of TPY-2 isn't 6 m2 but 9.2 m2.
TPY2A.PNG
and its side isn't 1.4 meter unless you think these guys in this photo are all dwarf
TPY-2.PNG

SBX radar is even bigger than TPY-2
SBX.jpg



Based on my experience, I know that the scanning sector of such radars in standby mode is 90 * 15
No one with experience would confuse between atmospheric attenuation and basic free space basic path loss


I'm tired. I showed you that two radars with the same scanning and energy properties, but different in wavelength (1.1 m and 0.03 m) will have different losses. This difference is 31 dB. Do you agree with that?
You wouldn't be tired if you just took my advice, open a book and learn the different between atmospheric attenuation and basic free space basic path loss ;)
Secondly, as I explained earlier, the free space path loss is caused by the spread out of radio wave as they propagate through space, it is literally the inverse square law working.

radar free space basic loss.PNG

Before you argue "why does the loss increase with frequency if they both follow the inverse square law", remember that you compared the two radar with same beam width, but one radar use VHF frequency and the other one use X-band. That lead to the aperture area of your VHF radar being 111.5 m2 and the aperture area of the X-band radar being 0.082 m2, in other words, the VHF radar in your example is 1359 times bigger than the X band radar. Because this free space path loss is literally the spread of beam over distance, a bigger radar aperture will collect signal from greater area, and that why the loss is less for bigger antenna even though both follow the inverse square law principles. I repeat again, this has nothing to do with atmospheric attenuation
However, when you put everything inside Rmax equation, and there isn't an insane size different between the X-band and VHF radar then X-band radar win hand down in term of detection range. That why your claim that RCS at VHF is only 5 times bigger than in X-band make no sense, because if that is the case than X-band is a much better anti stealth tool.



And you were given figures and official source, you basically just quibbling
We walk in circles.
1. Chinese experts are not an official source, just like Ukrainian experts. The point is simple. You like the Chinese number, but not the Ukrainian one.
2. LM presentation, does not contain figures. The air defense loss graph cannot be compared with the RCS numbers.
3. The words of the LM representative do not contain figures, but only abstractions that can be interpreted as you like.
4. The article of the Air Force Major, has figures. But they were taken from a certain writer. Where did the writer get these figures- I don't know.
In addition, these figures do not agree with other sources for a small RCS. They claim that the RCS B-2 is less than the F-117.
1. Because the Chinese number actually reference a real life incident ;)
2. Yes , it can be compared with number, they very carefully divided the graph into equal section, 5 folds reduction in detection range can be translate to percentage reduction in RCS
detection range.PNG
3. There is nothing particularly abstraction about golf ball or marble, they have explained before that they often used a ball to talk about RCS as the RCS of it is independent of aspect so easier to imagine.
4. The Air Force Major with all his experiences certainly think the numbers are accurate enough to cite;)
5. Depend on frequency, at lower frequency it isn't hard to imagine B-2 will have much lower RCS


Understand, if the person was not sure, then he would have picked up a more general word. But he indicates exactly the value (figure).
At the same time, non-standard direction angles, such as 45, 90, etc. And clearly 50.
He gave his estimate by his naked eye, that it. There is no requirement for him to be absolutely accurate with his estimate and given the condition he was in, it is quite impossible for him make super accurate estimate. In high stake situation, people have been shown to misidentify criminal suspects, pilots have been shown to mistaken between the sky and the ocean and die. Those are the things which are much harder to mistaken and people still misidentify them, nevermind something small like a different between 50-65 degrees or even his bank angle.

Let it be a poorly photoshopped picture. Like this one. :D
View attachment 648151
And as we can both see in that one, the F-22 carry not just 1 but 2 fuel tanks ;)



Well, experts from two Taiwanese institutes believe that the RCS of the F-22 from the nose, at a frequency of 2 GHz is 12 m2
1610193819847.png


https://www.researchgate.net/public...sign_Key_Factors_and_Limitation_of_Simulation
I understand that you will now say that they are complete fools, because you will not like this figure. But they did the same as the Chinese specialist
On the other hand, I would say that their simulation certainly better than the vague number from the Ukraine. But unlike you, I look deeper than the surface, I care about the model as well
At first, the number seem weird for a stealth aircraft, 10 dBsm at front aspect is quite high even when consider that the model is a perfect conductor and has no RAM or edge treatment. Then I look at their scattering chart and even the breakdown between vertical and horizontal polarization and I find another strange characteristic. The very strong 12 dBsm scattering lobe is directly at the front with very narrow angle. What type of reflector has that scattering characteristic? A flat plate.

vertical.PNG

Then I look at their model and it all clicked ;) instead of modelling an S shaped inlet duct, they literally covered it with a flat metal plate. That is why they have such a strong reflection lobes directly in front of the aircraft an in such a narrow angle.
model.PNG
Isn't it strange that they spend such a long time to do such a detail simulation but overlook such obvious detail? Then I read their study and realize that they mentioned that as the primary reason for the high RCS. If you read their study, then you should know the reason for the high RCS value as well.;)
reason.PNG

The S-duct is very important in RCS simulation because not only that it is a strong source of reflection, it is probably the only place on the stealth aircraft where the RAM absorption rating get accumulated to extremely high value of 50-60 dB due to multiple bounce of the signal. I don't blame them though, most simulation doesn't do the inlet correctly or just out right ignore it


We have already found out that we do not know which radars he is comparing on his diagram. And to estimate the RCS from this picture is like looking for numbers in the LM presentation by the percentage of losses from air defense. There is nothing that one could catch on to get at least some numbers. There are not even indirect signs by which something could be determined
There detection range show as km in the photo so you can't say there is no number. The VHF is JY-27, and while there is no mentioned of the exact type of the cm band radar, it is quite safe to conclude that it is something that does similar task to JY-27 and not some crazy comparison like a VHF air defense radar and a missile seeker.
 

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1635yankee

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Models studied at the Central Scientific Research Institute of the Aerospace Forces of the Ministry of Defense of the Russian Federation (NII VVKO). Former name "2nd Scientific Research Institute of the Ministry of Defense"
View attachment 648110

View attachment 648111

View attachment 648112

View attachment 648113

View attachment 648114

This is how full-size models are suspended on a rotating platform.
View attachment 648115

And irradiated in different wavelength bands
View attachment 648116
I mean, any computer simulation does not give high-quality results.
A properly designed and written simulation will give results that are very close to reality. I don't know what your experience simulation is with computer modeling systems, but they are used because they do give high quality results.
 

Dev

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Secondly, the area of TPY-2 isn't 6 m2 but 9.2 m2.
American Physical Society, Report of the APS Study Group on Boost-Phase Intercept Systems for National Missile Defense, Vol. 2, July 2003, p. 177.
Specifically, this study says an effective aperture of 6 m2 and a physical aperture of 9.2 m2

and its side isn't 1.4 meter unless you think these guys in this photo are all dwarf
See the message above.

SBX radar is even bigger than TPY-2
Honestly, I don't understand what kind of monster it is. And what is its purpose. They say that this is generally a radar for the HAARP project.
It is also known that not all modules are installed, so it is difficult for me to determine the exact dimensions of the antenna.

Before you argue "why does the loss increase with frequency if they both follow the inverse square law", remember that you compared the two radar with same beam width, but one radar use VHF frequency and the other one use X-band. That lead to the aperture area of your VHF radar being 111.5 m2 and the aperture area of the X-band radar being 0.082 m2, in other words, the VHF radar in your example is 1359 times bigger than the X band radar. Because this free space path loss is literally the spread of beam over distance, a bigger radar aperture will collect signal from greater area, and that why the loss is less for bigger antenna even though both follow the inverse square law principles. I repeat again, this has nothing to do with atmospheric attenuation
However, when you put everything inside Rmax equation, and there isn't an insane size different between the X-band and VHF radar then X-band radar win hand down in term of detection range. That why your claim that RCS at VHF is only 5 times bigger than in X-band make no sense, because if that is the case than X-band is a much better anti stealth tool.
Of course, I took with the same beam width and gain. How else?
Listen to yourself ...
You make an x-band radar so that its energetic characteristics coincide with the long-wave radar, you increase the gain by increasing the area. Thereby reducing the beam width.
Yes, you have created an x-band radar that has the same size, range, but very long scan times.
And now you say that this radar is better than the long-wave one. Than? The size is the same, the scan time of the standard 60 * 60 sector is 10 minutes instead of 10 seconds.
Don't you find it funny yourself? :D

No one with experience would confuse between atmospheric attenuation and basic free space basic path loss
You nobly forgive me for my English. :D
91Н6Е in static anti-missile defense mode scans the sector 25 * 20 (500 square degrees) or 60 * 30 (1800 square degrees). For TPY, I took an average of 1350 square degrees.

And as we can both see in that one, the F-22 carry not just 1 but 2 fuel tanks ;)
Do you really believe that RCS values are obtained in close contact between two aircraft? :D
There is foreign policy intelligence for this.

2. Yes , it can be compared with number, they very carefully divided the graph into equal section, 5 folds reduction in detection range can be translate to percentage reduction in RCS
Dismiss me from looking for a black cat in a black room. I'm not going to look for hidden meanings where there are none.
There will be numbers - there will be a conversation.

He gave his estimate by his naked eye, that it. There is no requirement for him to be absolutely accurate with his estimate and given the condition he was in, it is quite impossible for him make super accurate estimate. In high stake situation, people have been shown to misidentify criminal suspects, pilots have been shown to mistaken between the sky and the ocean and die. Those are the things which are much harder to mistaken and people still misidentify them, nevermind something small like a different between 50-65 degrees or even his bank angle.
I'm not very interested in your distortion of Zelko's words.

Then I look at their model and it all clicked ;) instead of modelling an S shaped inlet duct, they literally covered it with a flat metal plate. That is why they have such a strong reflection lobes directly in front of the aircraft an in such a narrow angle.
Show me in any of the simulations you have given before, is the air intake plugged?
Here's the fun part, but later.
Until then, answer the question.
Do you trust this article?
 
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tequilashooter

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«Колоссальный прорыв»: российские учёные разработали новый способ обнаружения самолётов-невидимок — РТ на русском (rt.com)

The characteristic feature of stealth technology is a significant reduction in the effective scattering area. Invisible is called an aircraft, which has this figure of less than 0.4 sq m.

As noted by Kornev, such an aircraft will not remain invisible to modern radar stations, but its detection causes a number of difficulties, negatively affecting the responsiveness of the air defense troops.

"Under certain conditions and at certain angles, the invisible can be overlooked, especially at long distances, which hypothetically allows the enemy aircraft to perform a combat mission. As far as I understand, in order to prevent such a development, RTI, together with other enterprises, has developed a method that captures the radar shadow," Says Kornev.

"Now it is too early to talk about the imminent implementation of a new method of breeding moving objects. To date, it has been proven that it is theoretically possible. There's still a lot of work to do. I think it's going to take about seven years. But if all goes well, this method will give Russia a noticeable advantage on the battlefield," Denisentsev said.

Yuri Knutov believes that scientists will certainly bring the invention to practical implementation, as the military is certainly interested in it. According to the analyst, the new method of selecting moving objects almost 100% guarantees the fixation of stealth-based devices over long distances.

"In my opinion, this is a huge breakthrough, which allows you to display on the screen so-called invisibles. It is important that with the help of synthesized aperture scientists were able to reduce the level of diaper errors. As a result, the principle of radar has been developed, which will detect any shadow, and the computer will calculate its exact location, which will allow the air defense forces to make a timely decision on counteraction," Knutov concluded.


Reported before, but it seems they gave a time estimate for its implementation later like seven years. I am wondering if anyone has heard of a method elsewhere before in regards to stealth aircrafts detection?

"I cannot imagine the B-2 having been designed without the influence of his work," Dr. Mitzner added. "Let me put it this way: without Ufimtsev, today's stealth aircraft would probably have looked the way the speculative artists portrayed them, before their real shapes were publicly disclosed"

"Rosetta Stone breakthrough for stealth technology" as said directly by Ben Rich -the Director of the team at SkunkWorks charged to carry on the XST program.


If all this involves complex math for making stealth and trying to defeat stealth at the end than why are the Russians not 1st or 2nd place other than the U.S. and Chinese students competing for top 2 spots? I am not even getting started with all the other crazy shit military related projects they are doing.

U.S. mathletes.jpg
 
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LMFS

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@tequilashooter

The way I understand that: the shadow of a plane can be noticed in a bistatic system, in a monostatic one that looks directly to the sky that looks difficult. But a system like an OTH radar is always receiving ground clutter, so the shadow of a stealth plane blocking known returns would be noticeable. That would be a tool even if modern planes are designed to be very stealthy against very long wavelengths... a pity that those "incredible" -70 dBsm in the end are only going to help detecting the B-21 better ;)
 

Dev

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If all this involves complex math for making stealth and trying to defeat stealth at the end than why are the Russians not 1st or 2nd place other than the U.S. and Chinese students competing for top 2 spots? I am not even getting started with all the other crazy shit military related projects they are doing.
But we have been taking the first places in programming(ICPC) since 2012.
1610234641934.png
 

tequilashooter

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2nd place in 2018 and 2020. Just saying.
You referring to the Chinese or the U.S.? sorry if I am being oblivious.
But we have been taking the first places in programming(ICPC) since 2012.
Yeah I know

ICPC 2019.png




Maybe that is why they are doing better with autonomous flights with the Su-70 because that involves high level of programming for everything to work right.
 

tequilashooter

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other than the U.S. and Chinese
Judging by the faces of the US team, only the Chinese win. :D

Sorry, I didn't mean to offend anyone.
There is still hope for the U.S. in the long run as long as there is no ban in Chinese immigration depending on the future demographics of the country. Its a positive stereotype so I doubt anyone Asian is offended.
 

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Colleagues, I apologize for the offtopic. Although the topic has long since departed from its name. I am not very familiar with the threads of this forum.
Prompt a stream of books.
I am intrigued by the books of David C. Aronstein
Have Blue and the F-117A: Evolution of the "Stealth Fighter"

and
Advanced Tactical Fighter to F-22 Raptor: Origins of the 21st Century Air Dominance Fighter
They're historical account on the creations of the respective aircraft. might not be interesting for technical purpose.

The 2nd book however is bit more depth but it doesnt touch the RCS topics. The appendix contains rather generalized view on RCS's,
 

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They're historical account on the creations of the respective aircraft. might not be interesting for technical purpose.

The 2nd book however is bit more depth but it doesnt touch the RCS topics. The appendix contains rather generalized view on RCS's,
I am interested in the very history of the creation of these aircraft. I understand that the technical specifications are not there.
 

stealthflanker

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They're historical account on the creations of the respective aircraft. might not be interesting for technical purpose.

The 2nd book however is bit more depth but it doesnt touch the RCS topics. The appendix contains rather generalized view on RCS's,
I am interested in the very history of the creation of these aircraft. I understand that the technical specifications are not there.
Then, those two are wonderful books. very well sourced.

definitely worth to own.
 

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Could the participants in this topic:

1) please use JPG rather than PNG format (unless for line drawings)
2) please use thumbnails, rather than full size images, as we have users still on dialup.
 

Dev

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There detection range show as km in the photo so you can't say there is no number.

And what does this Figures tell you?
We don't know which radars he is comparing.
Okay, as an example.

The detection range of the S-125 of the F-117 aircraft is 26 km.
From the same document, we know that the RCS of F-117 is 0.2, both in centimeter and decimeter bands.

This corresponds to the Red zone in the screenshot.

And here is the decimeter "Protivnik-GE", for the same target with an RCS of 0.2. Range 400 km.
This corresponds to the Blue zone in the screenshot.

So you want to say that Wu Jian Qi proved with his screenshot that the RCS of the F-117 is 0.2? :D
 
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Russian air and missile defense systems control the airspace around the Russian Federation for thousands of kilometers. This was announced on January 17 by I. about. Foreign Minister Sergei Lavrov , noting that domestic air defense missile defense systems were able to detect six American fifth-generation F-35 fighters near Iran's borders a few hours after the Islamic Republic's missile strike on the night of January 8 at bases in Iraqi territory where the US military is stationed ...

According to and. about. Foreign Minister of the Russian Federation, “at that time in the air on the border with the airspace of Iran there were at least six F-35s. “This information still needs to be rechecked, but it underscores the whole nervousness of the situation,” the head of the Foreign Ministry said at the time.

To date, one long-range radar station (radar) is working in this direction - the “Container” over-the-horizon radar. The spice is that F-35 multirole fighters are considered "invisible". And they are seen thousands of kilometers from the Middle East region from the territory of Russia, writes the portal "Russian Weapon".


How close do aircrafts usually fly next to each other on missions?
 

Dev

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Minister Sergei Lavrov , noting that domestic air defense missile defense systems were able to detect six American fifth-generation F-35 fighters near Iran's borders a few hours
Lavrov's direct speech.
"в это время в воздухе на границе с воздушным пространством Ирана было минимум шесть F-35. Эта информация еще требует перепроверки, но подчеркивает всю нервозность ситуации"

"At that time, there were at least six F-35s in the air on the border with Iranian airspace. This information still needs to be rechecked, but underlines the entire nervousness of the situation."
Was it a "container", a radar station, or a local resident with binoculars - "This information still needs to be rechecked" ;) :D
 

tequilashooter

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Was it a "container", a radar station, or a local resident with binoculars - "This information still needs to be rechecked"
I have found different sources saying 5,000 and different sources saying 10,000 objects. its able to classify UAVs, cruise missiles, passenger plains, tactical aircrafts etc based on HF, so if we were to pretend that it had a super shitty spatial resolution(high doubts on that) for example if we were to say the HF RCS value of a UAV would be 3m2, cruise missile, 7m2, F-35 13m2 passenger plane 30m2. The 26m2 and 39m2 readings would probably tell that 2-3 F-35s are close on that particular spatial resolutions etc, and if they decide to launch decoys for example that will just add little RCS value to the HF radar readings that something was launched. Sounds like it will have good target footprints with that many objects being monitored anyways.

You cant fool the OTH radar, unless you have the capabilities to shapeshift the aircraft :D
 
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Ronny

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Honestly, I don't understand what kind of monster it is. And what is its purpose. They say that this is generally a radar for the HAARP project.
It is also known that not all modules are installed, so it is difficult for me to determine the exact dimensions of the antenna.
That just some conspiracy BS
SBX is used for anti ballistic missile defense , the radar has about 45000 T/R modules


Of course, I took with the same beam width and gain. How else?
Listen to yourself ...
You make an x-band radar so that its energetic characteristics coincide with the long-wave radar, you increase the gain by increasing the area. Thereby reducing the beam width.
Yes, you have created an x-band radar that has the same size, range, but very long scan times.
And now you say that this radar is better than the long-wave one. Than? The size is the same, the scan time of the standard 60 * 60 sector is 10 minutes instead of 10 seconds.
Don't you find it funny yourself? :D
What make you think the X-band and VHF band radar in my example have the same size or even the same range? o_O
X band radar is 20 times smaller than the VHF band radar, and yet it can detect target from 60% longer range.
That why I said what you claimed about RCS doesn't make sense because X-band ended up having much longer detection range against stealth aircraft even with a smaller radar.
X band vs VHF.jpg

Do you really believe that RCS values are obtained in close contact between two aircraft? :D
There is foreign policy intelligence for this.
and there are counter intelligent. Nevertheless, I was replied to the claim that US F-22 operate in the same theater as Russia aircraft, therefore they must know its true RCS.


Dismiss me from looking for a black cat in a black room. I'm not going to look for hidden meanings where there are none.
There will be numbers - there will be a conversation.
;) If that was the only data point, there were a serial of evidences that pretty much support the same conclusion
_ Various articles repeat the statement from USAF and LM
_ The comparison statement from Wallace the senior manager for F-35 flight operation and former chief of B-2 low observability
_ The detection range chart from Wu Jian Qi the chief engineer of CETC
_ Monograph by Major Michael F. Hake of US airforce
_ The slides from Lockheed Martin clearly showing the 5 fold reduction in detection range
_ Several radar scattering simulation showing frontal RCS between -10 to -20 dBsm even without the application of RAM and especially at the S-duct which have accumulate absorption effect.


I'm not very interested in your distortion of Zelko's words.
What you interested in is quite irrelevant, I just tell it like it is. That number a naked eye ball angle estimation from a guy when he suddenly realize that he was being attacked.

Show me in any of the simulations you have given before, is the air intake plugged?
;) The F-35 simulation I cite earlier did model the inlet, not the absolute correct shape yet, but far better than to put the flat plate at the inlet location
1.jpg

Here's the fun part, but later.
Until then, answer the question.
Do you trust this article?
Trust is subjective. To what extent?
I don't believe F-35 absolute RCS value is exactly like the simulation show, because they can't model RAM and RAS, which is very important , especially in the inlet duct because the accumulated effect of S-duct and RAM can reduce the return from that area by 50-60 dB. They can't model edge treatment either
But I sure believe the scattering lobe have similar pattern to their simulation
 
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Ronny

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There detection range show as km in the photo so you can't say there is no number.

And what does this Figures tell you?
We don't know which radars he is comparing.
Okay, as an example.

The detection range of the S-125 of the F-117 aircraft is 26 km.
From the same document, we know that the RCS of F-117 is 0.2, both in centimeter and decimeter bands.

This corresponds to the Red zone in the screenshot.

And here is the decimeter "Protivnik-GE", for the same target with an RCS of 0.2. Range 400 km.
This corresponds to the Blue zone in the screenshot.

So you want to say that Wu Jian Qi proved with his screenshot that the RCS of the F-117 is 0.2? :D
If you want to twist his comparison by comparing an ancient X-band radar to a very new L band radar then go ahead, I can't stop you ;)
But he also mentioned that in 2013, JY-27 was the only radar they have that can detect F-22, no other ground or airborne radar could. Logically, he would be comparing VHF and cm radar from the same generation.
Also, if RCS at L-band is 0.2 m2 then it won't be 0.2 m2 at X band unless you think shaping, ram have the same effect at such a wide range.
 

Dev

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That just some conspiracy BS
SBX is used for anti ballistic missile defense , the radar has about 45000 T/R modules
I don't know the characteristics of SBX.
Bring them in, and then we will discuss them. The range is clear, you need dimensions, range for a typical target, and the time it takes to view a sector.

What make you think the X-band and VHF band radar in my example have the same size or even the same range? o_O
X band radar is 20 times smaller than the VHF band radar, and yet it can detect target from 60% longer range.
That why I said what you claimed about RCS doesn't make sense because X-band ended up having much longer detection range against stealth aircraft even with a smaller radar.
With the size, I exaggerated a little. But just a little bit. I don't know how you calculate ...
Did you intentionally reduce the gain of the long-wave radar? If we assume that your radar is square, then the side length will be 9 meters, which for a wavelength of 3 m will give a beam width of 21-22 degrees. P-18 - 6 degrees, ТNEBO-M - 4 degrees.
Let me try, and you will correct.
There is a radar of a meter range, with the characteristics as I indicated above.


Beam width = 6 degrees
Wavelength = 1.1m
These are our constants.
Find the diameter = (65 * 1.1) / 6 = ~ 12m
Area = ~ 111.5 m2
Gain = (4 * PI * 111.5) / (1.1 ^ 2) = 1158.3 or 30.6 dB
Frequency = 272.5 MHz
The task is to find the level of the returned signal in front of the antenna.
Options.
Power 20 kW (73 dBm), Range 100 km, RCS of the target 5 m2

x = ((30.6 * 2) + 73 - (103.4 + 20 * LOG10 (272.5) + 40 * LOG10 (100) -10 * LOG10 (5))) = -90.8 dBm

A task. Create an x-band radar with the same distance of parameters, taking into account that the RCS of a typical target in the x-band is decreased by 5 times. Without increasing power.
That is, we should get the same signal level in front of the antenna (-90.8 dBm) by increasing the gain.
We take the same formula.

((Х * 2) + 73 - (103.4 + 20 * LOG10 (10000) + 40 * LOG10 (100) -10 * LOG10 (1))) = -90.8 dBm
X= 49.80 dB or 95500
Further, knowing the gain and wavelength, we find the area. According to the formula you gave above.
95500=(4п*x)/0.03^2
X = Area = 6.83 m
Diameter = 2,94
As you can see, we reduced the size of the antenna by only 4 times, judging by the diameter.
Let's calculate the size of the beam at our gain.
65*0,03/2,94 = 0,66 degrees
Longwave radar, scanned sector 60 * 60 in (3600 / (6 * 6)) * 0.02 = 2 seconds
X-band radar (3600 / (0.66 * 0.66)) * 0.02 = 165 seconds.

So which radar would you choose?

;) The F-35 simulation I cite earlier did model the inlet
As I understand it, you did not read further ...
On the same page.

3.jpg

Frontal RCS with calculated air intake is -1.48 dBm2 or 0.7 m2.

By the way, in the same document RCS F-22 is estimated at 0.1 m2. On page 5

That is, one more article, gave figures that you do not like? :D
;) If that was the only data point, there were a serial of evidences that pretty much support the same conclusion
_ Various articles repeat the statement from USAF and LM
_ The comparison statement from Wallace the senior manager for F-35 flight operation and former chief of B-2 low observability
_ The detection range chart from Wu Jian Qi the chief engineer of CETC
_ Monograph by Major Michael F. Hake of US airforce
_ The slides from Lockheed Martin clearly showing the 5 fold reduction in detection range
_ Several radar scattering simulation showing frontal RCS between -10 to -20 dBsm even without the application of RAM and especially at the S-duct which have accumulate absorption effect.
I am not discussing indirect signs.
These are questions of faith. And fortunately we are not at the church forum.
.

If you want to twist his comparison by comparing an ancient X-band radar to a very new L band radar then go ahead, I can't stop you ;)
This is what I want to tell you that indirect data can be juggled in different ways. Naturally, I do not know which radar station he took in his presentation. I just picked the ones that fit this picture.
But you keep referring to them.
Therefore, our conversation moves from constructive to faith.
But questions of faith are not interesting to me.
 
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Inst

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Short answer, bullshit aside:

Russians ran a RCS sim of the F-22, and got an AVERAGE RCS figure of 0.4 m^2 in either one or an average of bands.

RCS varies depending on azimuth and angles, as well as frequency. A stealth aircraft isn't actually stealthy to radar in all directions and frequencies, it's just stealthy in certain directions toward certain frequencies. The frequency its stealth is optimized vs is based on likely enemy radars (easier to stealth vs extremely high frequency radars like X-band and Ku-band), but the aircraft can control its orientation relative to an emitter simply by turning.

IIRC, F-22 in Russian / Chinese RCS sims is around 0.1 m^2 (as an approximated average). The Su-57 is around 0.4 m^2, so it should be somewhat less stealthy than the F-22.

The current gold standard for fighter stealth should be the F-35, which has a RCS of around -50 m^2 dBsm based on some estimates in certain angles and frequencies, thanks to the F-35's small size and more advanced RAM. The F-22, J-20, Su-57 are all behind that, with a bunch of arbitrary rankings.
 

tequilashooter

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F-35 .00001m2 yeah trust me I agree with that because the B-21 is .0000001m2 and I think that the F/A-XX will be .000000001m2 or smaller than that, I just hope I did not screw up with my zero placements, but what worries me is that the photonic radar would see .00000000001m2 and that the radar shadowing technique would go .0000000000000000001m2.

Jesus Christ if Sukhoi or LM engineers stumbled on this thread they will be bawling their eyes out laughing at us.
 

Ronny

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I don't know the characteristics of SBX.
Bring them in, and then we will discuss them. The range is clear, you need dimensions, range for a typical target, and the time it takes to view a sector.
sbx dimension.PNG
sbx detection range 1.PNG


With the size, I exaggerated a little. But just a little bit. I don't know how you calculate ...
Did you intentionally reduce the gain of the long-wave radar? If we assume that your radar is square, then the side length will be 9 meters, which for a wavelength of 3 m will give a beam width of 21-22 degrees. P-18 - 6 degrees, ТNEBO-M - 4 degrees.
Let me try, and you will correct.
There is a radar of a meter range, with the characteristics as I indicated above.


Beam width = 6 degrees
Wavelength = 1.1m
These are our constants.
Find the diameter = (65 * 1.1) / 6 = ~ 12m
Area = ~ 111.5 m2
Gain = (4 * PI * 111.5) / (1.1 ^ 2) = 1158.3 or 30.6 dB
Frequency = 272.5 MHz
The task is to find the level of the returned signal in front of the antenna.
Options.
Power 20 kW (73 dBm), Range 100 km, RCS of the target 5 m2

x = ((30.6 * 2) + 73 - (103.4 + 20 * LOG10 (272.5) + 40 * LOG10 (100) -10 * LOG10 (5))) = -90.8 dBm

A task. Create an x-band radar with the same distance of parameters, taking into account that the RCS of a typical target in the x-band is decreased by 5 times. Without increasing power.
That is, we should get the same signal level in front of the antenna (-90.8 dBm) by increasing the gain.
We take the same formula.

((Х * 2) + 73 - (103.4 + 20 * LOG10 (10000) + 40 * LOG10 (100) -10 * LOG10 (1))) = -90.8 dBm
X= 49.80 dB or 95500
Further, knowing the gain and wavelength, we find the area. According to the formula you gave above.
95500=(4п*x)/0.03^2
X = Area = 6.83 m
Diameter = 2,94
As you can see, we reduced the size of the antenna by only 4 times, judging by the diameter.
Let's calculate the size of the beam at our gain.
65*0,03/2,94 = 0,66 degrees
Longwave radar, scanned sector 60 * 60 in (3600 / (6 * 6)) * 0.02 = 2 seconds
X-band radar (3600 / (0.66 * 0.66)) * 0.02 = 165 seconds.

So which radar would you choose?
Firstly, 4 times bigger diameter will lead to about 16 times bigger antenna.
Secondly, I would still choose the X band radar, the scan time is longer than VHF one but it is 10 times more accurate and aperture area is 16 times smaller. If you are very concern about the scan time, the beam can be cued by RWR. Also possible to divide big antenna into smaller section for multi beams scanning.
But that not the point, the point is the alleged significant detection range advantage of VHF radar over X-band when used against stealth aircraft is no where to be found if RCS at VHF is only 5 times bigger than RCS at x band
VHF-X band.JPG



As I understand it, you did not read further ...
On the same page.

View attachment 648357

Frontal RCS with calculated air intake is -1.48 dBm2 or 0.7 m2.

By the way, in the same document RCS F-22 is estimated at 0.1 m2. On page 5

That is, one more article, gave figures that you do not like? :D
I told you earlier, I judge the scattering data not just on the graph value, but how they arrived at the number.
You must loved the Taiwanese F-22 scattering chart huh? ;) sort of a "ha got you moment"?. Did it pissed you off when I pointed out the main reason for the huge frontal lobes is the two big flat plate they substitute for the inlet duct? ;)
joking aside, the inlet duct as shown in their simulation is a very significant source of radar return, especially when the end is shield off with a flat plate. Fortunately as we learn earlier, the massive advantage of S-duct is the ability to bounce radar signal multiple time before they got out. So even a RAM layer with low absorption rating of 5 dB can be accumulated to over 60 dB, the more bounces the wave make before it get out, the higher absorption rate :D, and that for very slight curve duct, now imagine what the duct of F-22/35 can do when they can use RAM with higher absorption rating and can bounce radar wave many more times
inlet 2.jpg
anyway, I don't see their estimation for F-22 RCS, but even 0.1 m2 is still quite good consider that the effect of RAM especially at the duct wasn't included yet

I am not discussing indirect signs.
These are questions of faith. And fortunately we are not at the church forum.
;) it certainly take church like faith to believe Russia can have the exact RCS of F-22 before it even fully finished
 
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Dev

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Good tracking radar. But not a surveillance radar. ;)
The baseball cheered up again. :D

Secondly, I would still choose the X band radar, the scan time is longer than VHF one but it is 10 times more accurate and aperture area is 16 times smaller.
Do you need such accuracy when reviewing a standard sector in 3 minutes? In 3 minutes they will release a bunch of "harms" at you, turn around and leave. And for another 3 minutes, your radar will not even see the "harm" that hit it. :D

But that not the point, the point is the alleged significant detection range advantage of VHF radar over X-band when used against stealth aircraft is no where to be found if RCS at VHF is only 5 times bigger than RCS at x band
Can you bring other figures of similar object in different bands?

You must loved the Taiwanese F-22 scattering chart huh? ;) sort of a "ha got you moment"?. Did it pissed you off when I pointed out the main reason for the huge frontal lobes is the two big flat plate they substitute for the inlet duct? ;)
Of course not. I cited an article by Taiwanese experts, just to show that such calculations are not very indicative. And the spread of numbers is very large. From 12 m2 to 0.7 m2.
Also, if Taiwanese specialists counted as an air intake as a flat plane (as Knot does in their book), then the RCS would be 30-40 dBms, not 12 m2.;)

;) it certainly take church like faith to believe Russia can have the exact RCS of F-22 before it even fully finished
I am not forcing anyone to believe in these numbers. And it seems to me they are quite objective than the definition by indirect signs, such as pictures, pea-balls, and diagrams of radar stations unknown to us.
 
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quellish

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Fortunately as we learn earlier, the massive advantage of S-duct is the ability to bounce radar signal multiple time before they got out.

Just like with the outside of the aircraft the shape of a cavity can be designed to reduce the signature. Inlet ducts are often designed with signature reduction through reflection as a goal.

That said, turbine faces look like bright strobe lights to some radars. The ducts prevent the poor radar from getting stuck staring straight into the strobes.

So even a RAM layer with low absorption rating of 5 dB can be accumulated to over 60 dB, the more bounces the wave make before it get out, the higher absorption rate :D, and that for very slight curve duct, now imagine what the duct of F-22/35 can do when they can use RAM with higher absorption rating and can bounce radar wave many more times

RAM with an "absorbtion rating" of 5 dB is not "low". There are physical and practical limits to what RAM can do, even over a narrow range of frequencies. Absorbing 20 db for a narrow range of frequencies on is pretty good (flat plate, normal to it). More than that and you are starting to run into the limits of what it is possible to absorb. There is no 100db RAM (and the physical limits are much, much closer to 20 than 100).

Ideally, when RF energy hits RAM in a cavity and "bounces" like you describe the signal is reduced by X (say, 5 db) each time. That means that the first hit is 5db less, then the second is 5db less of the signal that came out of the first "bounce". So the reduction does not accumulate as much as you seem to be describing.

In reality it is even less, as the RAM can become saturated with RF energy. It may not be able to absorb 5db on the 3rd bounce, etc.
 

rooster

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Fortunately as we learn earlier, the massive advantage of S-duct is the ability to bounce radar signal multiple time before they got out.

Just like with the outside of the aircraft the shape of a cavity can be designed to reduce the signature. Inlet ducts are often designed with signature reduction through reflection as a goal.

That said, turbine faces look like bright strobe lights to some radars. The ducts prevent the poor radar from getting stuck staring straight into the strobes.

So even a RAM layer with low absorption rating of 5 dB can be accumulated to over 60 dB, the more bounces the wave make before it get out, the higher absorption rate :D, and that for very slight curve duct, now imagine what the duct of F-22/35 can do when they can use RAM with higher absorption rating and can bounce radar wave many more times

RAM with an "absorbtion rating" of 5 dB is not "low". There are physical and practical limits to what RAM can do, even over a narrow range of frequencies. Absorbing 20 db for a narrow range of frequencies on is pretty good (flat plate, normal to it). More than that and you are starting to run into the limits of what it is possible to absorb. There is no 100db RAM (and the physical limits are much, much closer to 20 than 100).

Ideally, when RF energy hits RAM in a cavity and "bounces" like you describe the signal is reduced by X (say, 5 db) each time. That means that the first hit is 5db less, then the second is 5db less of the signal that came out of the first "bounce". So the reduction does not accumulate as much as you seem to be describing.

In reality it is even less, as the RAM can become saturated with RF energy. It may not be able to absorb 5db on the 3rd bounce, etc.
I have an article someplace on one of my computers that discusses the blackjack having coatings on the compressor blades versus hiding them via the bones tactic of hiding them. I will try and locate it. I am not a coatings engineer to know if that's possible or not.
 

Ronny

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Good tracking radar. But not a surveillance radar. ;)
The baseball cheered up again. :D
I only cited SBX because you said no one would want a long range radar with long scanning time ;)

Do you need such accuracy when reviewing a standard sector in 3 minutes? In 3 minutes they will release a bunch of "harms" at you, turn around and leave. And for another 3 minutes, your radar will not even see the "harm" that hit it. :D
120*20 sector is pretty standard for phased array radar, targets from 0 km- 18 km will be cover from distance of 50 km out to 400 km. Targets at altitude higher than 18 km and at closer range might need higher elevation but then for closer distance you can set a small section of the aperture to do quick short range scan.
And you don't need 3 minutes, more like 13 seconds as calculated above.
Secondly, AESA and PESA have extremely weak and narrow sidelobes, so unless they are looking directly at you, then you can't detect it to launch HARMs.


Can you bring other figures of similar object in different bands?
What do you mean?


Of course not. I cited an article by Taiwanese experts, just to show that such calculations are not very indicative. And the spread of numbers is very large. From 12 m2 to 0.7 m2.
Also, if Taiwanese specialists counted as an air intake as a flat plane (as Knot does in their book), then the RCS would be 30-40 dBms, not 12 m2.;)
It is actually very indicative because you can see not only the value but also the lobes location. And if you pay attention on their 3D models, you will even know exactly why specific angle have strong reflection lobes and others doesn't.
Also, Taiwanese specialists did use as flat plate to cover the air inlet, as they clearly mentioned it in their study actually. The different with Knot book is due to the frequency used.

I am not forcing anyone to believe in these numbers. And it seems to me they are quite objective than the definition by indirect signs, such as pictures, pea-balls, and diagrams of radar
As they are not the manufacturer, the way they give an arbitrary number without showing the 3D model used to get the result (inlet S duct model or not?, RAM applied or not? what type?) and method of measurement (simulation or measurement? , VV or HH?) is questionable at best, for others third party simulation, whether it is Greece, China or Taiwan, the type of model they use and their simulation method is quite clear for analyze
 

Ronny

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RAM with an "absorbtion rating" of 5 dB is not "low". There are physical and practical limits to what RAM can do, even over a narrow range of frequencies. Absorbing 20 db for a narrow range of frequencies on is pretty good (flat plate, normal to it). More than that and you are starting to run into the limits of what it is possible to absorb. There is no 100db RAM (and the physical limits are much, much closer to 20 than 100).
rating of 5 dB is pretty mild for X-band range, and while there is no 100 dB RAM, the different between 20 dB and 5 dB is pretty massive, even more massive with multiple bounce.
RAM 1.PNG
RAM 2.PNG

Ideally, when RF energy hits RAM in a cavity and "bounces" like you describe the signal is reduced by X (say, 5 db) each time. That means that the first hit is 5db less, then the second is 5db less of the signal that came out of the first "bounce". So the reduction does not accumulate as much as you seem to be describing.
Yes you are correct, I just took the end result from knots, so may be the energy reduced that much because it bounces more times than I thought
In reality it is even less, as the RAM can become saturated with RF energy. It may not be able to absorb 5db on the 3rd bounce, etc.
I don't think you can over saturated the RAM with radar energy at beyond visual range.
 

Dev

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I only cited SBX because you said no one would want a long range radar with long scanning time ;)
But you did not give the scan time.
Anyway ... SBX is a specific radar.
For example, I could not go to the x-range according to your data.
And you can't fool nature! Even if I take the antenna array pitch equal to the wavelength, completely destroying electronic scanning and violating antenna theory, then I get 74 mm. Let me remind you that the upper limit of the x-band is 37.5 mm.
Try to calculate you, maybe you will succeed.

120*20 sector is pretty standard for phased array radar, targets from 0 km- 18 km will be cover from distance of 50 km out to 400 km. Targets at altitude higher than 18 km and at closer range might need higher elevation but then for closer distance you can set a small section of the aperture to do quick short range scan.
91Н6Е in static mode, scans sector 60 * 30 (1800) in 6 seconds for an instrumental range of 600 km.
You can take these data as a basis for surveillance radars.
And you don't need 3 minutes, more like 13 seconds as calculated above.
Didn't see 13 seconds in your messages.

Secondly, AESA and PESA have extremely weak and narrow sidelobes, so unless they are looking directly at you, then you can't detect it to launch HARMs.
It doesn't matter, It is important that the review time is longer than the rocket arrival time.

What do you mean?
Can you provide data on unobtrusive objects (Type F-117) in different ranges from radar manufacturers? For example from Northrop Grumman Electronic Systems or Raytheon.

It is actually very indicative because you can see not only the value but also the lobes location. And if you pay attention on their 3D models, you will even know exactly why specific angle have strong reflection lobes and others doesn't.
Also, Taiwanese specialists did use as flat plate to cover the air inlet, as they clearly mentioned it in their study actually. The different with Knot book is due to the frequency used.
It is significant that each article does not carry reliable information. Or partially reliable. Therefore, you cannot refer to them. I will write a little later about the air intakes, and about the TsAGI research.

As they are not the manufacturer, the way they give an arbitrary number without showing the 3D model used to get the result (inlet S duct model or not?, RAM applied or not? what type?) and method of measurement (simulation or measurement? , VV or HH?) is questionable at best, for others third party simulation, whether it is Greece, China or Taiwan, the type of model they use and their simulation method is quite clear for analyze
I gave all the main parameters of these data (frequency, radiation angle, etc.). Naturally, these figures are given taking into account everything. It makes no sense to analyze the capabilities of the modernized complex, hiding some factors. These are not just guys who are going to get a degree. These guys sell air defense systems, including to NATO countries, and to countries that participate in the F-35 program. And the lie would be revealed immediately.

For general development. Russian experts believe that the RAM on aircraft is used at the Crowley BX113 level. It is ideally suited for mechanical and other properties for aircraft.
 

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We know that it is the air intake that makes the main contribution to the RCS from the front view. Chinese experts have estimated the S-shaped air intake at 75 m2. According to the Knot, the use of RAM will lower this value by 1000 times.
That is, the RCS of the F-35 air intakes can be estimated at 0.075 m2. This figure also agrees with the studies of the Russian TsAGI. One air intake of dimensions close to the existing ones, with RAM, at a wavelength of 3.2 cm, was estimated at 0.027 m2.
That is, two air intakes will amount to 0.054 m2.
With a high degree of confidence, it can be argued that S-shaped air intakes on modern aircraft contribute to the RCS of not less than 0.075-0.055 m2 or on average -12 dbsm.
Based on this, all sources that provide figures less than -12 dBsm can be considered unreliable.
We are not even talking about -20 dBsm , not to mention -30 dBsm or -40 dBsm.
 
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quellish

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One air intake of dimensions close to the existing ones, with RAM, at a wavelength of 3.2 cm, was estimated at 0.027 m2.
That is, two air intakes will amount to 0.054 m2.

Adding the “RCS” of individual components will not give you the RCS of the whole.

1610638874001.jpeg
 
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