Intake design and general stealth discussions

[Dev]

other than the U.S. and Chinese

Judging by the faces of the US team, only the Chinese win.

Sorry, I didn't mean to offend anyone.

 

[tequilashooter]

other than the U.S. and Chinese

Judging by the faces of the US team, only the Chinese win.

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.

 

[stealthflanker]

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,

 

[Dev]

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]

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.

 

[overscan (PaulMM)]

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.

 

[helmutkohl]

View attachment 648204

just quoting this pic.
if stealth jets can't be detected until close range.
would this mean two stealth jets (say an Su-57 and an F-35) would both have to get up close to detect each other?
perhaps making WVR missiles more important than before?

 

[Dev]

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.

Spoiler: +

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.

Spoiler: +

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?

 

[tequilashooter]

«Контейнер» всё увидит: НАТО не подобраться к границам России незамеченным: EADaily

По словам и. о. главы МИД РФ, «в это время в воздухе на границе с воздушным пространством Ирана было минимум шесть F-35. «Эта информация ещё требует перепроверки, но подчёркивает всю нервозность ситуации», — отметил тогда руководитель внешнеполитического ведомства. 20 января 2020. EADaily

eadaily.com

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]

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"

 

[tequilashooter]

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

 

[Ronny]

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?

What make you think the X-band and VHF band radar in my example have the same size or even the same range?
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.

Do you really believe that RCS values are obtained in close contact between two aircraft?
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

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

 

[Ronny]

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?

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]

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?
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.

Spoiler: +

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.

Spoiler: +

((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.



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?

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.

 

[Inst]

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]

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.

 

[overscan (PaulMM)]

This topic is not going anywhere.

 

[Ronny]

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.

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.

Spoiler: +

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.

Spoiler: +

((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

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?

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 , 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

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

 

[Dev]

Good tracking radar. But not a surveillance radar.
The baseball cheered up again.

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.

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.

 

[quellish]

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 , 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]

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 , 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]

Good tracking radar. But not a surveillance radar.
The baseball cheered up again.

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.

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]

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.

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]

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.

 

[Dev]

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.

 

[quellish]

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.

 

[Dev]

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

Nothing prevents Chinese experts from adding RCS.
It may not be necessary to fold, but it is unlikely that two air intakes will reflect less than one.

 

[Ronny]

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.

There isn't any detail about scan time. The scan time can be varied because it is a very big AESA radar so you could very well divide the aperture into smaller part for multi beam scanning.
And you calculation is incorrect because the whole aperture isn't filled

Didn't see 13 seconds in your messages.

Look at my last image comparing VHF and X band, the scan time part.

It doesn't matter, It is important that the review time is longer than the rocket arrival time.

Firstly, it isn't longer.
Secondly, you pretty much won't detect the phased radar unless they looking at you because the side lobe is very weak, especially with things like Taylor 40 weighting. So before they looking at you, you wont be able to launch HARMs at them

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.

China and Russian only have stealth aircraft in production quite recently, so range data against F-117 type target isn't what USA radar manufacturer aim to advertise

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.

The scattering characteristic of the shape is reliable, ofcourse these articles aren't perfect, but at least they are very open about their methodologies so it is very easy to identify the flaws

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.

It not about whether they try to take into account everything, it just that there are information that would be impossible for them to know or acquire such as the type of RAM used. Or in case of the S-200 manual, they can't even know the exact external shape of F-22 yet because it isn't fully finished at that point, there was quite a lot of different between YF-22 and F-22. To analyze the internal hidden inlet duct is even more impossible.
And Lockheed Martin also tried to sell their aircraft to many countries, apply the same logic as above, their 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.

Can you highlight for me, where does they say that in the S-200 manual or in the Ukraine study?
And what is the absorbing rating, center frequency of Crowley BX113? How is it compare to Ironball on F-117 or Fibermat on F-35?

 

[Ronny]

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.

It doesn't work like that, the amount of radar energy that an S-duct can absorb depend on the number of bounces that radar wave make before they hit the engine first stage and the number of bounce they make before they get out of the duct. Knots model a very slight curve duct, have you seen the duct of F-22 or F-35? They have very prominent curve that will let to many more radar bounce.

Secondly, the amount of radar wave that the duct can absorbed is also depend on the type of RAM used. The one with 20 dB absorption rating is sure different from the one with 10 or 5 dB absorption level.

In addition, engine first fan stage has much lower RCS than a simple flat plate as simulated by Knot and the Chinese study

 

[Dev]

There isn't any detail about scan time.

Then there is nothing to discuss.

And you calculation is incorrect because the whole aperture isn't filled

What data you gave, such a calculation turned out.

Look at my last image comparing VHF and X band, the scan time part.

I don't understand how you got this figure.
Diameter = 3 meters
beam width = 65 * 0.025 / 3 = 0.541 in one plane or
0.541 ^ 2 = 0.3 square degrees.
Your sector is 120 * 20 = 2400 square degrees
2400 / 0.3 * 0.02 = 160 seconds
My sector, which a real radar passes through in 6 seconds.
60 * 30 = 1800
1800 / 0.3 * 0.02 = 120 seconds.
That is, your radar will scan this sector 20 times slower.

Secondly, you pretty much won't detect the phased radar unless they looking at you because the side lobe is very weak, especially with things like Taylor 40 weighting. So before they looking at you, you wont be able to launch HARMs at them

I do not know exactly how the harm works, but the inertial guidance system has been used on Russian missiles for a long time, if the radar is turned off. And it doesn't matter. Launch a rocket at the coordinates.

China and Russian only have stealth aircraft in production quite recently, so range data against F-117 type target isn't what USA radar manufacturer aim to advertise

If there is no data, then there is no point in talking further. So far, we have data from the Russian side. Will appear from the United States - we will compare.

It not about whether they try to take into account everything, it just that there are information that would be impossible for them to know or acquire such as the type of RAM used. Or in case of the S-200 manual, they can't even know the exact external shape of F-22 yet because it isn't fully finished at that point, there was quite a lot of different between YF-22 and F-22. To analyze the internal hidden inlet duct is even more impossible.

How this data was obtained, alas, we will never know.

And Lockheed Martin also tried to sell their aircraft to many countries, apply the same logic as above, their lie would be revealed immediately

LM never mentioned these numbers. Therefore, it is difficult to find fault with them. I have already told you more than once, all the numbers with a small RCS, called the journalists. Likewise, researchers in their articles. But as we have already understood that the articles cannot be trusted.

And what is the absorbing rating, center frequency of Crowley BX113? How is it compare to Ironball on F-117 or Fibermat on F-35?

I have no data on the coverage you specified.
If you have? Compare.
a) absorption from wavelength at different thicknesses.
b) reflection from the angle of incidence at a wavelength of 3 cm.
I will be grateful.

It doesn't work like that, the amount of radar energy that an S-duct can absorb depend on the number of bounces that radar wave make before they hit the engine first stage and the number of bounce they make before they get out of the duct. Knots model a very slight curve duct, have you seen the duct of F-22 or F-35? They have very prominent curve that will let to many more radar bounce.

This is all clear. I also do not believe that these articles have a plausible result. As the others.

 

[Ronny]

Then there is nothing to discuss.

There are, your original point was basically that a big X-band radar won't be useful because it take too long to scan.
I showed extremely big X-band radar.

What data you gave, such a calculation turned out.

I thought you did research and know the aperture isn't fully filled? You even mentioned that

I don't understand how you got this figure.
Diameter = 3 meters
beam width = 65 * 0.025 / 3 = 0.541 in one plane or
0.541 ^ 2 = 0.3 square degrees.
Your sector is 120 * 20 = 2400 square degrees
2400 / 0.3 * 0.02 = 160 seconds
My sector, which a real radar passes through in 6 seconds.
60 * 30 = 1800
1800 / 0.3 * 0.02 = 120 seconds.
That is, your radar will scan this sector 20 times slower.

It in the number of pulse you send. 0.02 seconds in each beam position mean you send around 10 pulse down each position and the instrumental distance is about 300 km. But with massively powerful radar such as the one in our example, you can send fewer pulse down each beam position to reduce scan time.

I do not know exactly how the harm works, but the inertial guidance system has been used on Russian missiles for a long time, if the radar is turned off. And it doesn't matter. Launch a rocket at the coordinates.

I think you misunderstood how anti radar missile work. Unless they are static radar and their position is known before hand, you need to detect/geolocate the radar with your RWR before you launch anti radar missile at them. Only after you geolocate their position then the INS guidance is helpful. For phased array radars, if they don't look at you you, then you won't detect them because their sidelobes are very weak.

How this data was obtained, alas, we will never know.

Given the circumstance, it just guess work.

LM never mentioned these numbers. Therefore, it is difficult to find fault with them. I have already told you more than once, all the numbers with a small RCS, called the journalists. Likewise, researchers in their articles. But as we have already understood that the articles cannot be trusted.

They do mentioned the number, your choice of treating these balls, marble comparison as open to interpretation is just your choice.
I explained before, this is the traditional way they used to give RCS of targets, by comparing its with metal ball of different size, because a ball have same RCS from all direction and easy to visualize.
If you read the book: "Skunk Works A personal Memoir of my years at Lockheed" written by Ben Rich the engineer and the second Director of Lockheed's Skunk Works, also known as the farther of stealth, you will see this "ball, marble comparison has some tradition"
If you interested in a number, this story in the same book from Denys Overholser (the stealth engineer) is useful as a starting point.
When they wanted to test their full scale model, the RCS of the pole was too high, higher than the model itself and the RCS of the pole is only -20 dBsm



And this is where the tradition of comparing RCS to ball came from :



They achieved RCS so low that there were doubt that they were cheating, so US government literally make them glue the ball to the nose of the aircraft to see if the ball is detectable


The magnitude of RCS reduction over previous aircraft isn't hundreds times but thousands time

 

[Ronny]

I have no data on the coverage you specified.
If you have? Compare.
a) absorption from wavelength at different thicknesses.
b) reflection from the angle of incidence at a wavelength of 3 cm.
I will be grateful.
View attachment 648536

Firstly, can you show me the part in the S-200 manual or the Ukrainians study where they stated stealth aircraft use RAM similar to this?.
Secondly, I can't read Russian but based on the very noticeable Brewster angle in the second chart, I want to clarify that the reflection based on angle of incident here is the amount of front face reflection (meaning the amount of reflection came from the radar wave that doesn't entered the RAM to be absorbed)

 

[quellish]

I explained before, this is the traditional way they used to give RCS of targets, by comparing its with metal ball of different size, because a ball have same RCS from all direction and easy to visualize.
If you read the book: "Skunk Works A personal Memoir of my years at Lockheed" written by Ben Rich the engineer and the second Director of Lockheed's Skunk Works, also known as the farther of stealth, you will see this "ball, marble comparison has some tradition"

When we say something has an RCS of 1 sq m, what we are really saying is that the RCS is equivalent to that of a PEC sphere 1 m in diameter. That is how RCS measurements work.

When they wanted to test their full scale model, the RCS of the pole was too high, higher than the model itself and the RCS of the pole is only -20 dBsm

Obviously this was a complete waste of time. The Tver RCS range in Russia uses cables to suspend models in the air from towers. Lockheed should have used espionage to discover what material these cables are made of. They must be very very special to not completely screw up measurements, especially those of low observable models. Otherwise any measurement taken there would be very suspicious, and if those measurements were used to validate an analytical model the whole model would be flawed. You might end up designing "stealth" airplanes with antlers and Happy Fun Ball!

Lockheed could have built not only their pole but their airplane out of this cable material!

 

[Dev]

There are, your original point was basically that a big X-band radar won't be useful because it take too long to scan.
I showed extremely big X-band radar.

My point of view remains the same.
For tracking objects - a good radar.
If you want to prove otherwise, just give the scan time.

I thought you did research and know the aperture isn't fully filled? You even mentioned that

That's what I say. This is not a wrong calculation, this is the data that you provided is not correct.
If you have other data, let's recalculate the parameters.

It in the number of pulse you send. 0.02 seconds in each beam position mean you send around 10 pulse down each position and the instrumental distance is about 300 km. But with massively powerful radar such as the one in our example, you can send fewer pulse down each beam position to reduce scan time.

0.02 is the acquisition time per beam offset. This parameter for modern radars varies from 0.04 to 0.01. I took averages of 0.02. Why did you lower this parameter in your calculation by an order of magnitude, I do not know. I suspect that you are just jaggling the data to please yourself. Can you provide a surveillance radar with such parameters? If not, then I do not return to this topic anymore. I told you everything about it.

I think you misunderstood how anti radar missile work. Unless they are static radar and their position is known before hand, you need to detect/geolocate the radar with your RWR before you launch anti radar missile at them. Only after you geolocate their position then the INS guidance is helpful. For phased array radars, if they don't look at you you, then you won't detect them because their sidelobes are very weak.

The first serif will determine the direction. When approaching, I think there will be enough side petals. Typically they are 30 dB less than the main beam. But with your huge 50dB gain, even the sidelobes will be huge.
But that's not the point. The fact is that 100 km, the rocket will fly in 150 s, and you will find it too late.
And it doesn't even matter if it's an anti-radar missile. Air defense is not the goal itself. As a rule, air defense guards a static object (for example, an airfield).
In short, I don't need a radar with such a scan time!

Given the circumstance, it just guess work.

No one denied the assumption. And air defense systems continue to be sold.

They do mentioned the number, your choice of treating these balls, marble comparison as open to interpretation is just your choice.

But how does this all relate to reality? Yes, they tested the Hopeless Diamond model made of wood, which has never even flown, and is even different from the Have Blue. Yes, they have achieved a colossal reduction in EPR (by several orders of magnitude), but compared to what? With the bombers of the time. Yes, no doubt. And I will tell you even more, this is a very good result.

Firstly, can you show me the part in the S-200 manual or the Ukrainians study where they stated stealth aircraft use RAM similar to this?.

Of course this is not from the air defense documents. In air defense, RAM are not needed, they need a ready-made figure. This is from the work of TsAGI (an institute that deals with aerodynamics and electrodynamics, including in the interests of the Ministry of Defense). To evaluate the S-shaped air intakes, they took this material.

Secondly, I can't read Russian but based on the very noticeable Brewster angle in the second chart, I want to clarify that the reflection based on angle of incident here is the amount of front face reflection (meaning the amount of reflection came from the radar wave that doesn't entered the RAM to be absorbed)

As we know from physics, there is no absolutely black body. Something is always reflected. RAM also reflects. The second graph shows reflection / absorption versus incidence angle. That is, the absorption is maximum when the wave is incident perpendicularly (parallel polarization is a broken line).
With perpendicular polarization, the maximum absorption will be at 40-45 degrees.

 

[Ronny]

My point of view remains the same.
For tracking objects - a good radar.
If you want to prove otherwise, just give the scan time.

My point is simple: you basically said no one would want a big X-band because scan time is too long, so I showed you an X-band with massive aperture

That's what I say. This is not a wrong calculation, this is the data that you provided is not correct.
If you have other data, let's recalculate the parameters.

How is my data not correct? I gave you the correct aperture area and correct number of T/R modules.
You said yourself in earlier post that SBX aperture isn't fully filled, so I don't understand why you make some calculation assuming it is filled?

0.02 is the acquisition time per beam offset. This parameter for modern radars varies from 0.04 to 0.01. I took averages of 0.02. Why did you lower this parameter in your calculation by an order of magnitude, I do not know. I suspect that you are just jaggling the data to please yourself. Can you provide a surveillance radar with such parameters? If not, then I do not return to this topic anymore. I told you everything about it.

The acquisition per beam position depend on three factors:
1- The instrumental range, because the wave need to go out and reflected back
2- The number of pulse in each position
3- Pulse width
All three factors above can be adjusted depend on situation. Where did you get the "0.01-0.04 seconds" value from?

The first serif will determine the direction. When approaching, I think there will be enough side petals. Typically they are 30 dB less than the main beam. But with your huge 50dB gain, even the sidelobes will be huge.
But that's not the point. The fact is that 100 km, the rocket will fly in 150 s, and you will find it too late.
And it doesn't even matter if it's an anti-radar missile. Air defense is not the goal itself. As a rule, air defense guards a static object (for example, an airfield).
In short, I don't need a radar with such a scan time!

About 13 -20 seconds isn't really long scan time. For Taylor 40, the sidelobes is about 40 dB weaker than the main lobes, at long range, this energy will dissipate very quickly.

But how does this all relate to reality? Yes, they tested the Hopeless Diamond model made of wood, which has never even flown, and is even different from the Have Blue.

This is set up of HAWK
AN/MPQ-50 can track target 3 m2 target from 104 km and 1 m2 from 79 km. So if RCS of F-117 is 0.1 m2, then it should be detected from 44 km.





Have blue were fly against E-3 as well

Yes, they have achieved a colossal reduction in EPR (by several orders of magnitude), but compared to what? With the bombers of the time. Yes, no doubt. And I will tell you even more, this is a very good result.

I know you would say that ,but they didn't compared that with bomber of the time







Before you assume D-21 must have huge RCS, look what they did with SR-71:





Similar thing with F-35 recently

Of course this is not from the air defense documents. In air defense, RAM are not needed, they need a ready-made figure. This is from the work of TsAGI (an institute that deals with aerodynamics and electrodynamics, including in the interests of the Ministry of Defense). To evaluate the S-shaped air intakes, they took this material.

Wait a second, Have they ever mention the RAM and the RCS of F-22, F-35 and F-117 in the same document?

 

[Ronny]

As we know from physics, there is no absolutely black body. Something is always reflected. RAM also reflects. The second graph shows reflection / absorption versus incidence angle. That is, the absorption is maximum when the wave is incident perpendicularly (parallel polarization is a broken line).
With perpendicular polarization, the maximum absorption will be at 40-45 degrees.

Firstly, a black body in physic mean a body that absorb 100% energy at all frequency, it is very different from RAM designed to absorb radar energy at a narrow frequency range. In theory, you can make a Salisbury screen with 100% absorption at very narrow frequency, angle. You make a Salisbury screen by placing a thin sheet with same wave impendence as air (377 ohms/sq resistance) on top which allow radio wave to entered the RAM structure without being reflected back right at the surface, the sheet transform the short circuit at the back material into open circuit at the sheet, when the impendence of the sheet is 377 ohms/sq there is no reflection because load is matched. Yes, I know Salisbury isn't used on airplane typically because of the bulkiness and narrow band, but I just thought it is interesting to mention
Secondly, the second chart isn't about absorption, it is sort of reflection coefficient. Let say you have a radar beam hitting your RAM, a 0.1 reflection coefficient mean 10% of the beam reflected away right from the top RAM surface and 90% entered the RAM to be absorbed. The absorption then can be -10 db, -20 dB ..etc then the left over energy will reflect a second time when they hit the metal surface underneath the RAM.

 

[Dev]

My point is simple: you basically said no one would want a big X-band because scan time is too long, so I showed you an X-band with massive aperture

Well, give another scan time, thereby prove that this is a surveillance radar.
Can't you give the numbers? Then what are we discussing here?
Your guesses! No, they are not interesting to me.

How is my data not correct? I gave you the correct aperture area and correct number of T/R modules.
You said yourself in earlier post that SBX aperture isn't fully filled, so I don't understand why you make some calculation assuming it is filled?

Same. Can you provide the correct information? No! Then there is nothing to discuss. I am not interested in guesses.

Where did you get the "0.01-0.04 seconds" value from?

This average comes from the radars I know.
If you don't believe me, then you can ask a respected @stealthflanker what values he uses in his calculator(Dwell time).

About 13 -20 seconds isn't really long scan time.

This is the only value you got by cheating. Reducing the time by 10 times.

This is set up of HAWK
AN/MPQ-50 can track target 3 m2 target from 104 km and 1 m2 from 79 km. So if RCS of F-117 is 0.1 m2, then it should be detected from 44 km.

Are you sure that this is the data of those years. HAWK has been modernized more than once. If my memory serves me correctly.
The first S-125s also did not ensure the defeat of such targets.
This memoir is certainly a good book. And we even have it in Russian. But still imaginative literature, not technical. I would not trust her unconditionally in everything.

I know you would say that ,but they didn't compared that with bomber of the time

I do not know the of these objects. neither D-21 nor SR-71

Similar thing with F-35 recently

Wait a second, Have they ever mention the RAM and the RCS of F-22, F-35 and F-117 in the same document?

I do not have such a document. You have not read my messages correctly.

Firstly, a black body in physic mean a body that absorb 100% energy at all frequency, it is very different from RAM designed to absorb radar energy at a narrow frequency range. In theory, you can make a Salisbury screen with 100% absorption at very narrow frequency, angle. You make a Salisbury screen by placing a thin sheet with same wave impendence as air (377 ohms/sq resistance) on top which allow radio wave to entered the RAM structure without being reflected back right at the surface, the sheet transform the short circuit at the back material into open circuit at the sheet, when the impendence of the sheet is 377 ohms/sq there is no reflection because load is matched. Yes, I know Salisbury isn't used on airplane typically because of the bulkiness and narrow band, but I just thought it is interesting to mention

Fundamentals of physics are not interesting to me. Will RAM comparisons be from you?

Secondly, the second chart isn't about absorption, it is sort of reflection coefficient.

Why do you come up with something that is not. The second diagram shows the signal attenuation versus the angle of incidence. With a perpendicular incidence, with a perpendicular polarization, the absorption will be 17 dB. That is, the reflected signal will be -17 dB. Which is shown in the graph. All! And there is no need to invent anything superfluous.

 

[Scar]

US refusing to sell F-35 to any country that purchased S-400 because Americans don't want us to confirm experimentally the fact that F-35 cannot be seen by S-400(which would render it as useless and destroyed its sales) or any other LORAD at more or less significant range, due to F-35 super-tiny RCS, just as Americans told to the whole World all these years. I think we should be grateful to Americans - they don't want to ruin S-400 market success.

 

[tequilashooter]

they don't want to ruin S-400 market success.

Quite the contradiction there buddy, considering both sources are from two days ago.

Turkey to continue talks with Russia on 2nd batch of S-400s as planned: Erdoğan - Turkey News (hurriyetdailynews.com)

Exclusive: India's friction with U.S. rises over planned purchase of Russian S-400 defence systems | Reuters

Its sad, I just wanted to see a modern air defense network against a modern air force(military exercises like Israel and Greece).

 

[quellish]

Fundamentals of physics are not interesting to me.

Yes, that has become apparent.