• Hi Guest! Forum rules have been updated. All users please read here.

Su-57 RCS and general Stealth discussion

Ronny

ACCESS: Secret
Joined
Jul 20, 2019
Messages
367
Reaction score
145
@Ronny:
> F-117 downed, VLO RQ-170 detected and landed on Iran,
Stealth aircraft aren't supposed to be stealthy from all direction, I'm sure you know that. Even the most stealthy aircraft can be detected from the direction where it got strong reflection lobes.
In case of the F-117, it was tracked by a VHF radar, the frequency which it was not designed to be stealthy against. And when it was attacked, it shown the side to the battery, which if you looked at the scattering chart posted earlier, that where the RCS the highest
2D940CD2-4E62-4CCF-A224-9BEDF1C60564.jpeg

About RQ-170, it is a bit different from a normal stealth aircraft that it doesn't have pilot, it is an UAV, it might need constant transmission with the command center so it might be easier to show up on passive receiver. Secondly, as far as I know, they captured the RQ-170 by jamming GPS and feed it the wrong coordinate to land. That is much easier than to shot something down since you only need the general direction.

B-2 modified for low level penetration, trend towards stand-off weapons, autonomous jamming and unmanned aircraft, claims about counter-stealth US radars etc. do not reinforce the impression that US VLO works as claimed.
Recently instead of using Turkey's S-400 to show the world their superiority, they reacted in hiysteria at the prospect of those radars getting in close contact with the F-35... why not demonstrate they can dance circles around the system and ruin Russian reputation and their best military export item?
B-2 design was modified for low level mid way through development phase, for the fear that radar might advance too fast, they basically make a serration at the back. However, if you look at the design of B-21, you will see that it emphasize high altitude flight again and have pretty much the same shape as original B-2
The trend toward longer range weapon is understandable, all thing equal, stay at longer range is more safe. However, apart from stand off range weapons, they also develop many mininature weapons for stealth aircraft.
Unmanned aircraft and autonomus jamming are necessary, because not everything should be done by stealth aircraft. For stand in jamming for example, you just want something cheap.
I don't see the introduction of low frequency "anti stealth" radar as the proof that stealth doesn't work. I see that as, because stealth does work, that why these stuff get developed. Let me put it this way: do you think anyone develop HEAT and Sabot round if all tank armor can be penetrated by basic rifle?


> Russian position regarding expected RCS of Western fighter sized models has remained relatively stable through time in the order of magnitude of -10 dBsm. I don't know if it is right or what does it comprise exactly, but it has not changed too much over time actually, and it includes them operating in the same theater in Syria.
Yes their comments has been quite stable. On the other hand, they also developed quite a high number of "anti stealth" low frequency radars. If RCS of stealth aircraft are around 0.1 m2, I don't see why they need VHF radar to detect them. Even big fighter radar will track these aircraft from quite far, let alone big surface radar.
While Russia and Usa operating at the same time in Syria. Stealth fighter operate there always either carry external fuel tank or luneburg lens.
 
Last edited:

Dev

ACCESS: Confidential
Joined
Nov 11, 2019
Messages
56
Reaction score
31
Yes their comments has been quite stable. On the other hand, they also developed quite a high number of "anti stealth" low frequency radars.
Let's take a look at longwave radars. Imagine a radar with a circular antenna.
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
Remember this figure.

We do the same only for the X-band radar.

The beam width is the same. We don’t want to change the space scan time.
Wavelength 0.03 m.
diameter = 0.325 m
Area = ~ 0.082 m2
Gain = (4 * PI * 111.5) / (1.1 ^ 2) = 1158.3 or 30.6 dB
Frequency = 9993 MHz = 10 GHz
Power 20 kW (73 dBm), Range 100 km, RCS of the target 5 m2

x = -122.1 dBm
As you can see, the gain and width are completely interconnected.
But that's not the point. The signal level at the same levels dropped by 31 dB. This is atmospheric attenuation. 1,260 times.
How can we fill this gap?
We cannot change the gain. This will require a change in area and hence diameter. Which will change the beam width. But we don't need it.
Therefore, we need to increase the power. And it should be increased by 1,260 times.
I hope you understand that longwave radars are a trade in power for size.
This is the main benefit of longwave radars.
And they are not super weapons against stealth. They are 60 years old. The P-18 has been exploited in large numbers since 1971. Even before Have Blue was born.
 
Last edited:

Dev

ACCESS: Confidential
Joined
Nov 11, 2019
Messages
56
Reaction score
31
Catchy however, the slide shown by Wu Jian Qi, the chief engineer of China Electronics Technology Group Corporation is not a journalistic article, the F-16 radar scattering simulation from department of aeronautical science of Hellenic Airforce academy isn't a journalistic article, the actual F-117 metal model measurement in Bremen anechoic chamber isn't a journalistic article. The slide about radar detection range reduction from Lockheed Martin also not a journalist article.
Because you said: "Lockheed Martin not only have access to all three aircraft but also developing them"

So I'm waiting for the figures from the LM or at least from the Ministry of Defense.
But figures are not.

Instead of this,
Insects, balls and peas
Journalist Articles
Articles of Chinese non-military organizations
Retired employees
Screenshots from LM, but no numbers.
ETC
 
Last edited:

Dev

ACCESS: Confidential
Joined
Nov 11, 2019
Messages
56
Reaction score
31
Stealth aircraft aren't supposed to be stealthy from all direction, I'm sure you know that. Even the most stealthy aircraft can be detected from the direction where it got strong reflection lobes.
In case of the F-117, it was tracked by a VHF radar, the frequency which it was not designed to be stealthy against. And when it was attacked, it shown the side to the battery, which if you looked at the scattering chart posted earlier, that where the RCS the highest
And again there is a discrepancy.
From an interview with Dale Zelko (F-117 pilot)
The clouds were very low. I saw the rocket when it had already crossed the cloud layer, immediately after launch. She walked at an angle of 50 degrees to me. And as soon as I saw her, I realized: they had figured me out.

Let's take your picture. There are no peaks at the CHP-125 (8.9-9.46 GHz).
I don't think they will appear with an even greater decrease in wavelength.
1609980902097.png

Everything is ilac in your picture. -18dBsm or 0.0158 m2
A volley was fired at a distance of 13 km, defeat 10-11 km (from the report of Djordje Anichich).

Here is the F-16 affected area by the same SAM (Flight to the radar).
1609980929662.png

The range = 18 km.
RCS F-16 in the centimeter band of 2.5 m2. I think you will not argue with this.
Further, we count through the fourth root.
(0.0158 / 2.5) ^ 1/4 = 0.281
0.281 * 18 = 5 km


As you can see, if you believe your picture and the low RCS, then the Yugoslav anti-aircraft gunners had to launch missiles from a distance of 5 km. Before this distance, the missile guidance station (CHR-125) should not have seen it. But we know that the salvo came from a distance of 13 km.
 
Last edited:

LMFS

ACCESS: Confidential
Joined
Mar 19, 2019
Messages
110
Reaction score
129
About RQ-170, it is a bit different from a normal stealth aircraft that it doesn't have pilot, it is an UAV, it might need constant transmission with the command center so it might be easier to show up on passive receiver.
What is the point of creating an Ultra-Low-Observable alien-tech wonder and give it away with constant transmissions, so your enemy can easily capture it?

If RCS of stealth aircraft are around 0.1 m2, I don't see why they need VHF radar to detect them.
Again, with those figures we don't know the values of frontal RCS, which could and should be significantly lower, maybe one order of magnitude or maybe more, who knows.

In general, I have not read Russians dismiss LO design, but they laugh overtly at the values provided by the West... hell, with those new -70 dBsm claimed for B-21 I have laughing material for a good time too

The reality is that keeping control of a large theater of operations with air targets whose RCS is below 1 sqm and use good tactics is already quite difficult, therefore the success of Yemeni attacks against KSA or the surveillance of USN carriers with Iranian UAVs. I think the Internet battles about stealth are way too theoretical and do not seem to resemble at all what actually happens in the real world...

Rony said:
While Russia and Usa operating at the same time in Syria. Stealth fighter operate there always either carry external fuel tank or luneburg lens.
We know that at least F-22 did combat missions in Syria in LO configuration, it is said also Israeli F-35 did but this is not for sure. What we never have seen is proof they have flown over the S-400 as was expected.

Dev said:
Let's take your picture. There are no peaks at the CHP-125 (8.9-9.46 GHz).
Those models, do they have internals? Gaps? Fasteners and rivets? They can give any RCS as ridiculously low as you want, it will all be BS when real world issues kick in.
 
Last edited:

tequilashooter

ACCESS: Confidential
Joined
Jan 2, 2021
Messages
73
Reaction score
37
@Dev

Try to keep 3 posts into one post if your responding to the same person, before a moderator or admin drops by penalizing your account or something.
 

Dev

ACCESS: Confidential
Joined
Nov 11, 2019
Messages
56
Reaction score
31
Try to keep 3 posts into one post if your responding to the same person, before a moderator or admin drops by penalizing your account or something.
Okay, I'll keep that in mind in the future.
Thanks for the advice.

Those models, do they have internals? Gaps? Fasteners and rivets? They can give any RCS as ridiculously low as you want, it will all be BS when real world issues kick in.
I agree with you completely.
 
Last edited:

Ronny

ACCESS: Secret
Joined
Jul 20, 2019
Messages
367
Reaction score
145
Yes their comments has been quite stable. On the other hand, they also developed quite a high number of "anti stealth" low frequency radars.
Let's take a look at longwave radars. Imagine a radar with a circular antenna.
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
Remember this figure.

We do the same only for the X-band radar.

The beam width is the same. We don’t want to change the space scan time.
Wavelength 0.03 m.
diameter = 0.325 m
Area = ~ 0.082 m2
Gain = (4 * PI * 111.5) / (1.1 ^ 2) = 1158.3 or 30.6 dB
Frequency = 9993 MHz = 10 GHz
Power 20 kW (73 dBm), Range 100 km, RCS of the target 5 m2

x = -122.1 dBm
As you can see, the gain and width are completely interconnected.
I didn't tell you to keep the same beam width between the two radar, of course the X-band radar will have narrow beam, but you don't need to go overboard with it.
In your example: the antenna aperture area of the VHF radar is 1359 times bigger than the X-band radar ;) ,Is Nebo SVU that much bigger than an SPY-6? ;)
Try with a more realistic example:
X band radar:
Dimension: 5*5 meter -> Area: 25 m2
Operating frequency: 12 GHz - Wavelength: 0.025 m
Peak transmitting power: 1 MW
VHF band radar:
Dimension: 31*31 meter -> Area: 1000 m2
Operating frequency: 100 MHz - Wavelength: 3 m
Peak transmitting power: 1 MW
Target RCS at X band: 0.1 m2 , Target RCS at VHF: 0.5 m2

We have the equation for power density so just put all in the excel:

power density of reflected signal.PNG
Compare X band and VHF band.PNG

In short, if what you said about RCS was correct, the X-band radar with 40 times smaller antenna will still have 72 times better power density of reflected signal compared to the VHF radar. VHF wouldn't be anti stealth, in fact, it will have inferior detection range against stealth aircraft compared to X-band.


But that's not the point. The signal level at the same levels dropped by 31 dB. This is atmospheric attenuation. 1,260 times.
How can we fill this gap?
We cannot change the gain. This will require a change in area and hence diameter. Which will change the beam width. But we don't need it.
Therefore, we need to increase the power. And it should be increased by 1,260 times
I hope you understand that longwave radars are a trade in power for size.
This is the main benefit of longwave radars.
And they are not super weapons against stealth. They are 60 years old. The P-18 has been exploited in large numbers since 1971. Even before Have Blue was born.

I don't know who taught you that about atmospheric attenuation but you should have your money back
Atmospheric attenuation of 10 Ghz band when it travel 350 nm two way (or a total of 700 nm = 1296 km) is only 6.5 dB and that assuming the elevation is 0 where there is lens loss effect, with even a slight elevation angle of barely 5 degrees, the atmospheric attenuation is less than 2 dB
Capture.PNG
frequency attennuation vs elevation.PNG


Because you said: "Lockheed Martin not only have access to all three aircraft but also developing them"

So I'm waiting for the figures from the LM or at least from the Ministry of Defense.
But figures are not.

Instead of this,
Insects, balls and peas
Journalist Articles
Articles of Chinese non-military organizations
Retired employees
Screenshots from LM, but no numbers.
ETC
1- The insect, ball, pea comments was given by Robert Wallace, the senior flight operation for F-35 and former chief of low observability for the B-2
2- The journalist articles are quoting people of authority in the matter rather than doing their own analysis
3- CETC group isn't a non-military organization, they are a state owned corporation that manufactured many military equipment. As a matter of fact, YLC-8B radar, JY-27A radar and Silk Road Eye radar on KL-2000 were all made by them
CETC.PNG


4- 95% reduction in lethal SAM shot, and don't tell me that is the amount of RCS reduced, because right next to it, they also have the graph showing 5 fold decrease in air to air detection range. You simply can't achieve that with a only 10 times reduction in RCS

F-35 detection range reduction 2.PNG

Btw, I posted this as well:
important.PNG
rcs.PNG


And again there is a discrepancy.
From an interview with Dale Zelko (F-117 pilot)
The clouds were very low. I saw the rocket when it had already crossed the cloud layer, immediately after launch. She walked at an angle of 50 degrees to me. And as soon as I saw her, I realized: they had figured me out .g
The range = 18 km.
RCS F-16 in the centimeter band of 2.5 m2. I think you will not argue with this.
Further, we count through the fourth root.
(0.0158 / 2.5) ^ 1/4 = 0.281
0.281 * 18 = 5 km
As you can see, if you believe your picture and the low RCS, then the Yugoslav anti-aircraft gunners had to launch missiles from a distance of 5 km. Before this distance, the missile guidance station (CHR-125) should not have seen it. But we know that the salvo came from a distance of 13 km.
I have the video of the interview, he didn't mentioned anything about the angle of the missile, only that it penetrated the cloud, and let be real, F-117 didn't have a radar, a missile warning system, or a radar warning receiver. So at best, he was estimate the angle of the SAM with his naked eye, and on a high stake situation like that I don't expect anyone to have a highly accurate naked eye estimation of anything. He likely can't even distinguish between 30-50 degree at that moment
 
Last edited:

Ronny

ACCESS: Secret
Joined
Jul 20, 2019
Messages
367
Reaction score
145
What is the point of creating an Ultra-Low-Observable alien-tech wonder and give it away with constant transmissions, so your enemy can easily capture it?
I think it might use a high gain antenna to minimize the possibility of interception, but it is not perfect, could still be detected from some specific direction.

.Again, with those figures we don't know the values of frontal RCS, which could and should be significantly lower, maybe one order of magnitude or maybe more, who knows.
Dev seem to be quite confident that the frontal RCS of F-22 in X-band is 0.1 m2 and RCS in VHF is 0.5 m2

We know that at least F-22 did combat missions in Syria in LO configuration, it is said also Israeli F-35 did but this is not for sure. What we never have seen is proof they have flown over the S-400 as was expected.
Even in LO configuration, they can still hide true RCS with luneburg lens
 

Dev

ACCESS: Confidential
Joined
Nov 11, 2019
Messages
56
Reaction score
31
Try with a more realistic example:
Not realistic !!!!!
You are constantly forgetting about the beam width.
Under your conditions for the x-band, the beam width is 0.3 degrees. It takes 34,000 steps to scan a 60 * 60 sector. Modern radars scan this sector in about 10 s with a range of 150 km on average. The full view for the APG-81 is 19 seconds at a distance of 160 km. This is approximately 0.02 seconds per step. 34,000 * 0.02 = 654 s or 10 minutes.

In short, if what you said about RCS was correct, the X-band radar with 40 times smaller antenna will still have 72 times better power density of reflected signal compared to the VHF radar.
Yes, but I would not like to be the operator of such a radar station, in a combat situation, which scans the 60 * 60 sector in 10 minutes.

I don't know who taught you that about atmospheric attenuation but you should have your money back
:D :D
These are the recommendations of the ITU. The International Telecommunication Union (ITU) is the United Nations specialized agency for information and communication technologies – ICTs.

ITU-R P.525-2
1610025328660.png



I hope you won't argue with ITU.

1- The insect, ball, pea comments was given by Robert Wallace, the senior flight operation for F-35 and former chief of low observability for the B-2
2- The journalist articles are quoting people of authority in the matter rather than doing their own analysis
3- CETC group isn't a non-military organization, they are a state owned corporation that manufactured many military equipment. As a matter of fact, YLC-8B radar, JY-27A radar and Silk Road Eye radar on KL-2000 were all made by them
I suggest you stop. And they will return to the conversation when there are figures from official sources.
Btw, I posted this as well:
This is a monograph by an Air Force major who refers to some other writer. I never found the original source. But the author writes everything about everything.

Also, are you not confused by the B-2 figure? In all sources that give a low RCS level - This figure is much less.
The RCS of a stealth aircraft is typically multiple orders of magnitude lower than a conventional plane and is often comparable to that of a small bird or large insect. "From the front, the F/A-22's signature is -40dBm2 (the size of a marble) while the F-35's is -30 dBm2 (the size of a golf ball). The F-35 is said to have a small area of vulnerability from the rear because engineers reduced cost by not designing a radar blocker for the engine exhaust." [Aviation Week & Space Technology; 11/14/2005, page 27] The F-35 stealthiness is a bit better than the B-2 bomber, which, in turn, was twice as good as that on the even older F-117. B-2 stealth bomber has a very small cross section. The RCS of a B-26 bomber exceeds 35 dBm2 (3100m2 ) from certain angles. In contrast, the RCS of the B-2 stealth bomber is widely reported to be about -40dBm2 .

I have the video of the interview, he didn't mentioned anything about the angle of the missile, only that it penetrated the cloud, and let be real, F-117 didn't have a radar, a missile warning system, or a radar warning receiver. So at best, he was estimate the angle of the SAM with his naked eye, and on a high stake situation like that I don't expect anyone to have a highly accurate naked eye estimation of anything. He likely can't even distinguish between 30-50 degree at that moment
Here is an interview with Zelko in 2009.
Given to Aye Kuge.

Зелко Дейл: Была очень низкая облачность. Ракету я увидел, когда она уже пересекла слой облаков, сразу после запуска. Она шла под углом в 50 градусов ко мне.
Translate:
Zelko Dale: It was very cloudy. I saw the rocket when it had already crossed the cloud layer, immediately after launch. She walked at an angle of 50 degrees to me.

Yes, I admit that he could be wrong, but by + -10 degrees.
Otherwise, he would simply say that the rocket came from the right.
But there are no peaks in the 40-60 sector either.
 
Last edited:

LMFS

ACCESS: Confidential
Joined
Mar 19, 2019
Messages
110
Reaction score
129
Dev seem to be quite confident that the frontal RCS of F-22 in X-band is 0.1 m2 and RCS in VHF is 0.5 m2
I cannot speak for the veracity of any concrete source, I have no F-22 in my garage.

Even in LO configuration, they can still hide true RCS with luneburg lens
Sorry, that does not make any practical sense.
 
Last edited:

tanino_it

ACCESS: Restricted
Joined
Dec 2, 2019
Messages
5
Reaction score
2
I'd like to make an HTML5 infographic for the whole forum community (and post it on the site) comparing the various RCSs (including the B-21, even though -70DB seems like an exaggerated value, so even the S-70 could reach -50DB for sure! if I look at the configuration), but it's hard for me to come to any conclusions...
 

Dev

ACCESS: Confidential
Joined
Nov 11, 2019
Messages
56
Reaction score
31
I'd like to make an HTML5 infographic for the whole forum community (and post it on the site) comparing the various RCSs (including the B-21, even though -70DB seems like an exaggerated value, so even the S-70 could reach -50DB for sure! if I look at the configuration), but it's hard for me to come to any conclusions...
If it helps you. I can provide information on RCS that I have met on various objects in Russian literature and Russian articles. Naturally, for new developments, such as the Su-57 or S-70, I will not provide.
 

icyplanetnhc

ACCESS: Confidential
Joined
Aug 16, 2015
Messages
125
Reaction score
38
Website
aiaa.seas.ucla.edu
I have no F-22 in my garage.
You should travel to Florida I heard that there were like 17 F-22s damaged or destroyed in a hurricane so if the air force has no use for them you can always ask.


“Some of them got more damaged than others, but they all flew out of here, so I think that’s pretty incredible that that happened,” he said. “Some of them will take a little longer to repair to get back to full capability, but some of them that were left behind are back in our lineup flying every day.”
 
Last edited:

quellish

I am not actually here.
Senior Member
Joined
Aug 6, 2007
Messages
2,173
Reaction score
203
I don't think amateur simulation and military grade research are the same thing.

I disagree. Any person can educate themselves by studying the underlying physics at work and perform the *same* "military grade research". "Military researchers" do no have access to some secret physics knowledge.

For instance, you can have RAM, or you can have setups for destructive interference at a given wavelength of interest, without knowing the depth and characteristics of the RAM you are not going to be accurate.

Again, how much do you think that could reduce the RCS of a flat plate? An infinite amount?

Well, I assume such simulation is going to be reasonable to assess the basic geometry of a plane, but to analyse real world complexity, or when people are discussing abut RCS of 0.0001 sqm for a house-sized plane, this kind of simplified approach is not accurate enough.

The "basic geometry of a plane" is what determines almost all of the RCS. You can reflect far more energy than you could possibly absorb. That was the real innovation of the XST studies.

There are many free and commercial software packages (and services) for RCS prediction. POFACETS is just one, though one that is very easy to access. It is used by many universities and defense contractors performing "military grade research". There are certainly others that can do things that POFACETS does not do.

It is certainly more "accurate" than pasting "RCS" numbers found on the internet to compare two aircraft!

But to get back on topic, someone has already done public RCS prediction of the T-50 for you:

 

tequilashooter

ACCESS: Confidential
Joined
Jan 2, 2021
Messages
73
Reaction score
37
The "basic geometry of a plane" is what determines almost all of the RCS. You can reflect far more energy than you could possibly absorb. That was the real innovation of the XST studies.

There are many free and commercial software packages (and services) for RCS prediction. POFACETS is just one, though one that is very easy to access. It is used by many universities and defense contractors performing "military grade research". There are certainly others that can do things that POFACETS does not do.

It is certainly more "accurate" than pasting "RCS" numbers found on the internet to compare two aircraft!

But to get back on topic, someone has already done public RCS prediction of the T-50 for you:

(PDF) Constructing a 3D model of a complex object from 2D images, for the purpose of estimating its Radar Cross Section (RCS) (researchgate.net)

I think it depends on who does the public RCS prediction, such as you brought up POFACETS while others that have used such a software gave mean frontal RCS of F-35 model as -11dBsm and that there were a couple of higher RCS peaks in the aircrafts frontal arc. I have heard people tell me in the past that Aus Power has like some bias with the F-35, but not with the F-22(is that correct?) there might be a chance LMFS might dismiss it for reference purposes if he comes back online anyways because I assume he does not trust how aus airpower is more favorable of one US aircraft over the other, than he will have doubts Russian aircrafts based on aus air power's RCS analysis would be any better.
 

Ronny

ACCESS: Secret
Joined
Jul 20, 2019
Messages
367
Reaction score
145
Not realistic !!!!!
You are constantly forgetting about the beam width.
Under your conditions for the x-band, the beam width is 0.3 degrees. It takes 34,000 steps to scan a 60 * 60 sector. Modern radars scan this sector in about 10 s with a range of 150 km on average. The full view for the APG-81 is 19 seconds at a distance of 160 km. This is approximately 0.02 seconds per step. 34,000 * 0.02 = 654 s or 10 minutes.
Yes, but I would not like to be the operator of such a radar station, in a combat situation, which scans the 60 * 60 sector in 10 minutes.
That is a weak excuse consider that I'm comparing the detection range, not the scan time. The big reason VHF is often claimed as anti stealth is the much better detection range against stealth aircraft. But if what you said about RCS is correct, then VHF will have inferior detection range compared to X-bank
X band radar:
Dimension: 2*2 meter -> Area: 4 m2
VHF band radar:
Dimension: 20*4 meter -> Area: 80 m2
This time I added Rmax row for illustration ;) so tell me, how can they get superior range from VHF radar?
r max.png
X band vs VHF.PNG



:D :D
These are the recommendations of the ITU. The International Telecommunication Union (ITU) is the United Nations specialized agency for information and communication technologies – ICTs.

ITU-R P.525-2
View attachment 648002
I hope you won't argue with ITU.
Firstly, the chart I gave you came from IEEE
Secondly, I don't have to argue with ITU, you should open a book and learn the different between free space basic transmission loss and atmospheric attenuation.
Free space basic transmission loss has nothing to do with atmospheric attenuation, the free space path loss come from the spread out of signal, also known as the inverse square law
invsqr2.png

Thirdly, your equation is for isotropic antenna. Meaning it radiate in all direction
Omnidirectional-gain-at-3GHZ-a-3-D-radiation-Pattern-b-Polar-plot.png

I suggest you stop. And they will return to the conversation when there are figures from official sources.
The comparison by Robert Wallace, the senior flight operation for F-35 and former chief of low observability for the B-2 is official, the chart given by Wu Jian Qi, the chief engineer of LC-8B, JY-27A manufacturer is official, the chart given by Lockheed Martin is also official .


This is a monograph by an Air Force major who refers to some other writer. I never found the original source. But the author writes everything about everything.

Also, are you not confused by the B-2 figure? In all sources that give a low RCS level - This figure is much less.
The RCS of a stealth aircraft is typically multiple orders of magnitude lower than a conventional plane and is often comparable to that of a small bird or large insect. "From the front, the F/A-22's signature is -40dBm2 (the size of a marble) while the F-35's is -30 dBm2 (the size of a golf ball). The F-35 is said to have a small area of vulnerability from the rear because engineers reduced cost by not designing a radar blocker for the engine exhaust." [Aviation Week & Space Technology; 11/14/2005, page 27] The F-35 stealthiness is a bit better than the B-2 bomber, which, in turn, was twice as good as that on the even older F-117. B-2 stealth bomber has a very small cross section. The RCS of a B-26 bomber exceeds 35 dBm2 (3100m2 ) from certain angles. In contrast, the RCS of the B-2 stealth bomber is widely reported to be about -40dBm2 .
I thought you only believe official source?. For me it is more believable that at some frequency B-2 has bigger RCS than F-117 than to believe Eurofighter and F-16 pretty much have the same RCS as F-22 and F-35



Here is an interview with Zelko in 2009.
Given to Aye Kuge.
Yes, I admit that he could be wrong, but by + -10 degrees.
Otherwise, he would simply say that the rocket came from the right.
But there are no peaks in the 40-60 sector either.
There is quite a big peak at around 65 degrees. Nevertheless, it quite an impossible task to ask someone to make an accurate angle estimation with his eye when is literally being attacked by a missile the size of a telephone pole coming at him through the cloud cover. So +- 15 or even 20 degree inaccurate is understandable
F-117.PNG
 
Last edited:

Ronny

ACCESS: Secret
Joined
Jul 20, 2019
Messages
367
Reaction score
145
The "basic geometry of a plane" is what determines almost all of the RCS. You can reflect far more energy than you could possibly absorb. That was the real innovation of the XST studies.

There are many free and commercial software packages (and services) for RCS prediction. POFACETS is just one, though one that is very easy to access. It is used by many universities and defense contractors performing "military grade research". There are certainly others that can do things that POFACETS does not do.

It is certainly more "accurate" than pasting "RCS" numbers found on the internet to compare two aircraft!

But to get back on topic, someone has already done public RCS prediction of the T-50 for you:

(PDF) Constructing a 3D model of a complex object from 2D images, for the purpose of estimating its Radar Cross Section (RCS) (researchgate.net)

I think it depends on who does the public RCS prediction, such as you brought up POFACETS while others that have used such a software gave mean frontal RCS of F-35 model as -11dBsm and that there were a couple of higher RCS peaks in the aircrafts frontal arc. I have heard people tell me in the past that Aus Power has like some bias with the F-35, but not with the F-22(is that correct?) there might be a chance LMFS might dismiss it for reference purposes if he comes back online anyways because I assume he does not trust how aus airpower is more favorable of one US aircraft over the other, than he will have doubts Russian aircrafts based on aus air power's RCS analysis would be any better.
Small note: in that study, the F-35 model used for RCS simulation is the one without radome nose cone and canopy (they are assumed to be transparent to radar wave).

F-35 RCS no cone.PNG

studies where radome nose cone and canopy is model look like this
radar scattering.PNG
 
Last edited:

Ronny

ACCESS: Secret
Joined
Jul 20, 2019
Messages
367
Reaction score
145
They can distinguish helicopter, but not aircraft. Secondly, distinguish 2 helicopter at 2 locations is quite different from distinguish them while they are both inside the cell
discrimination.PNG

and their conclusion

conclusion.PNG



I cant copy and past so had to image upload.
Their current target spatial resolution at most was 7.5km JORN: a world leading OTHR capability - Australian Defence Magazine
The resolution is range dependent, at best is 7.5 km, but at worst is 75 km. Also no height
resolution.PNG
 

LMFS

ACCESS: Confidential
Joined
Mar 19, 2019
Messages
110
Reaction score
129
I disagree. Any person can educate themselves by studying the underlying physics at work and perform the *same* "military grade research". "Military researchers" do no have access to some secret physics knowledge.
Let us disagree then. That is not how things work according to my experience.

It is certainly more "accurate" than pasting "RCS" numbers found on the internet to compare two aircraft!
1610105595354.png
Look above the RCS calculation of a ball based on different methods... enough said.

But to get back on topic, someone has already done public RCS prediction of the T-50 for you:
Yes of course, this is an old known simulation, also based on PO, but still they say the following interesting things:

In conclusion, this study has established through Physical Optics simulation across nine frequency bands, that no fundamental obstacles exist in the shaping design of the T-50 prototype, which might preclude its development into a genuine Very Low Observable design with constrained angular coverage.
...
The latter underscores, as was the case with previous effort on the J-20 prototype, the difficulty in attempting to perform highly accurate numerical RCS modelling of foreign airframe designs, where access to high fidelity shaping data, surface feature data, and materials type and application is actively denied.
...
Importantly, if the results of the Physical Optics specular return modelling yield RCS values from key aspects, at key frequencies, which are consistent with stated VLO performance values in US designs, to an order of magnitude, it is reasonable to conclude that a mature T-50 design will qualify as a genuine VLO design.


So APA sees no problem with the VLO of the Su-57 in the frontal arc (basically the same limitation F-35 has), but let me remind you that the internet "experts" all decided that APA is a totally discredited because they were critical with the F-35, and also because they were very appreciative of the PAK-FA.

You are right, it is all disinformation. The F-22 is -60 dBsm in reality, so it can place some -40 dBsm sources on the fuselage and still be VLO while faking its real RCS. BTW, the same happens with PAK-FA, for which all the prototypes shown until now are just to fool the West, maskirovka!!
 

Dev

ACCESS: Confidential
Joined
Nov 11, 2019
Messages
56
Reaction score
31
That is a weak excuse consider that I'm comparing the detection range, not the scan time.
I told you at the beginning that radars are compromises. And no one needs a radar with good range parameters, but at the same time with poor scanning properties.

Dimension: 2*2 meter -> Area: 4 m2
Anyway, I don't want to be a radar operator that scans a small sector 60 * 60 in 1 minute 15 seconds. :D
As I said, this sector should be scanned in 10, maximum 15 seconds.

This time I added Rmax row for illustration ;) so tell me, how can they get superior range from VHF radar?
You don't need to get the VHF range! You need to bring your x-band radar to its normal scan time.

Secondly, I don't have to argue with ITU, you should open a book and learn the different between free space basic transmission loss and atmospheric attenuation.
But you are now engaged in a dispute with the ITU.
You can take this formula and substitute the same values, and get the same thing.

Thirdly, your equation is for isotropic antenna. Meaning it radiate in all direction
You are inattentive.
x = ((30.6 * 2) + 73 - (103.4 + 20 * LOG10 (272.5) + 40 * LOG10 (100) -10 * LOG10 (5))) = -90.8 dBm
This is gain. Twice, because gain affects both transmission and reciving.

The comparison by Robert Wallace, the senior flight operation for F-35 and former chief of low observability for the B-2 is official, the chart given by Wu Jian Qi, the chief engineer of LC-8B, JY-27A manufacturer is official, the chart given by Lockheed Martin is also official .
I'll get back to the conversation when there are figures from LM or the Ministry of Defense.
There are NO figures yet.

I thought you only believe official source?. For me it is more believable that at some frequency B-2 has bigger RCS than F-117 than to believe Eurofighter and F-16 pretty much have the same RCS as F-22 and F-35
I never found the source from the link in the article. Therefore, I cannot judge how official it is.

There is quite a big peak at around 65 degrees. Nevertheless, it quite an impossible task to ask someone to make an accurate angle estimation with his eye when is literally being attacked by a missile the size of a telephone pole coming at him through the cloud cover. So +- 15 or even 20 degree inaccurate is understandable
First, you got the sides mixed up.
Second, don't think that the US Air Force pilots are topographic critins. The cockpit is full of landmarks to determine the angle.
Thirdly, if you imagine the flight of the F-117 relative to the radar, you will understand that 50 degrees is the maximum at the end of the trajectory. The detection took place at a lower angle.
 

Ronny

ACCESS: Secret
Joined
Jul 20, 2019
Messages
367
Reaction score
145
But let me remind you that the internet "experts" all decided that APA is a totally discredited because they were critical with the F-35, and also because they were very appreciative of the PAK-FA.
APA was originally a very decent source, until their proposal of F-111 upgrade + F-22 plan get denied and replaced by F-35. After that point, all their analysis become quite trash because it always ended up the same way with everything from the East will destroy the F-35 just by existing and F-22 and F-111 is the solution for every problem. PAK-FA is just 1 of many things that they used as supposed F-35 destroyer

You are right, it is all disinformation. The F-22 is -60 dBsm in reality, so it can place some -40 dBsm sources on the fuselage and still be VLO while faking its real RCS. BTW, the same happens with PAK-FA, for which all the prototypes shown until now are just to fool the West, maskirovka!!
I don't think F-22 is -60 dBsm, and I certainly don't think it is -40 dBsm with the luneburg lens. The lens is also used so that air traffic radar can see them
 

LMFS

ACCESS: Confidential
Joined
Mar 19, 2019
Messages
110
Reaction score
129
Why the hell do you even need VLO against ISIS, whereas they at best had up to ten "Osa's"?
Because they were inside of Syria and didn't want problems with their AD, or that is what they said.
 

quellish

I am not actually here.
Senior Member
Joined
Aug 6, 2007
Messages
2,173
Reaction score
203

That's interesting. I have not read that paper, but back in 2010(?) a forum member did basically that for the J-20 around the time of its first flight. Generated a model from photographs and predicted the RCS as part of a discussion thread here on the forum.

I have heard people tell me in the past that Aus Power has like some bias with the F-35, but not with the F-22(is that correct?) there might be a chance LMFS might dismiss it for reference purposes if he comes back online anyways because I assume he does not trust how aus airpower is more favorable of one US aircraft over the other, than he will have doubts Russian aircrafts based on aus air power's RCS analysis would be any better.

So the assumption is that the RCS prediction was somehow tampered with?
Anyone can attempt to reproduce those results by using the same tools to predict the RCS. Again, I encourage those participating in this thread to do so. They will learn quite a bit in the process.
 

quellish

I am not actually here.
Senior Member
Joined
Aug 6, 2007
Messages
2,173
Reaction score
203
Look above the RCS calculation of a ball based on different methods... enough said.

That statement reinforces just about every point I have made in this thread. I again encourage those participating in the thread to learn about the underlying science.
 

Dev

ACCESS: Confidential
Joined
Nov 11, 2019
Messages
56
Reaction score
31
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"
1610130236375.png

1610130306769.png

1610130364935.png

1610130570613.png

1610130619837.png

This is how full-size models are suspended on a rotating platform.
1610131133581.png

And irradiated in different wavelength bands
1610131347736.png
I mean, any computer simulation does not give high-quality results.
 

Ronny

ACCESS: Secret
Joined
Jul 20, 2019
Messages
367
Reaction score
145
I told you at the beginning that radars are compromises. And no one needs a radar with good range parameters, but at the same time with poor scanning properties.
And I told you from the start that if what you said about RCS is correct, then VHF will never be developed/advertised as an anti stealth tool because their detection range against stealth aircraft will be less than X-band radar
And, do you want to know what is the operating frequency of these radars below?. Both in X-band.
TPY-2.jpg
sbx-1.jpg


Anyway, I don't want to be a radar operator that scans a small sector 60 * 60 in 1 minute 15 seconds. :D
As I said, this sector should be scanned in 10, maximum 15 seconds.
If scan time is absolutely important, nothing stop them from using a fraction of the array for shorter range quick scan and the rest for long range scan, we are in the age of AESA radar after all


You don't need to get the VHF range! You need to bring your x-band radar to its normal scan time.
Don't dodge the question, how to get this type of range advantage from VHF radar if what you said about RCS is correct?
146BDC8F-B36F-4806-9ECB-053079026EAA.jpeg



Secondly, I don't have to argue with ITU, you should open a book and learn the different between free space basic transmission loss and atmospheric attenuation.
But you are now engaged in a dispute with the ITU.
You can take this formula and substitute the same values, and get the same thing.
I didn't engage in any dispute with them , if you took my advice and opened a book, you will see that free space basic transmission loss and atmospheric attenuation are completely different things. Atmospheric attenuation is caused by the energy absorption of gas and molecules in the atmosphere, if you transmit radio wave in a vaccum, there is no atmospheric attenuation. Free space basic transmission loss is the lost caused by the spread of the radio beam over distance, you still have that even if you transmit radio wave in space vacuum.
Atmospheric attenuation:
link-power-budget-calculation-and-propagation-factors-for-satellite-communication-3-638.jpg

vs
Free space path loss
free space path loss.PNG
The comparison by Robert Wallace, the senior flight operation for F-35 and former chief of low observability for the B-2 is official, the chart given by Wu Jian Qi, the chief engineer of LC-8B, JY-27A manufacturer is official, the chart given by Lockheed Martin is also official .
I'll get back to the conversation when there are figures from LM or the Ministry of Defense.
There are NO figures yet.
There are already more than enough overwhelming evidences. You are just quibbling
The chart given by Wu Jian Qi has number on it, which can be used to deduce the stealth quantity
The comparison by Robert Wallace is straight forward and can be used to deduce the RCS
The charts and reduction percentages from LM slides are very straight forward and can be used to deduce the percentage of RCS reduction
The number given by Michael Hake is straight forward.
All these evidences support the same conclusion.


There is quite a big peak at around 65 degrees. Nevertheless, it quite an impossible task to ask someone to make an accurate angle estimation with his eye when is literally being attacked by a missile the size of a telephone pole coming at him through the cloud cover. So +- 15 or even 20 degree inaccurate is understandable
First, you got the sides mixed up.
Second, don't think that the US Air Force pilots are topographic critins. The cockpit is full of landmarks to determine the angle.
Thirdly, if you imagine the flight of the F-117 relative to the radar, you will understand that 50 degrees is the maximum at the end of the trajectory. The detection took place at a lower angle.
Firstly, the aircraft is pretty symmetrical so it doesn't matter
Secondly, when there is a telephone pole flying at you through the cloud cover at two - three time speed of sound then anyone can make inaccurate estimation, let alone something as small as the different of 50 and 65 degrees.
Thirdly, no. The detection was done by the P-18 radar, when the airplane got close, they tried to track it with the fire controlled radar, falling several times before finally acquired a lock and launch missile immediately. And also the aircraft was extremely close to the site, so even a small bank angle can lead to its tail making a 90 degrees with the ground radar
F-117 angle.png
 

Ronny

ACCESS: Secret
Joined
Jul 20, 2019
Messages
367
Reaction score
145
studies where radome and nose cone is model look like this
If you believe the Chinese experts, then maybe you will believe the Ukrainian ones too.:D
View attachment 648071

View attachment 648072

The thing is, how did they arrived at these numbers? did they made individual models for each airplane then test?, I don't think they did. And even if they do, what does their model look like?
And what does these number mean? average? min? max?

F-22 in Syria
Spoiler: +
Luneberg lenses are not observed.
Yes but is there any Russian airplane close by to analyze their RCS and are they tracked on Russian air defense radar?[/spoiler]
 

Ronny

ACCESS: Secret
Joined
Jul 20, 2019
Messages
367
Reaction score
145
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 648111

View attachment 648112

View attachment 648113


I mean, any computer simulation does not give high-quality results.

That actually look quite cheap and inaccurate compared to the kind of model USA used in their RCS test pole
f-18.PNG
F-35.PNG
222.PNG

The actual plane is used sometime
F-35_RCS_Test03.jpg
 

tequilashooter

ACCESS: Confidential
Joined
Jan 2, 2021
Messages
73
Reaction score
37
As satisfied as I am about the more than 1000fold improvement for smaller target detection with the usage of a sapphire crystal for targets from the achievements of that photonics team in Australia I have some following questions below here which relate to the last posts being discussed here.

At 100 nautical miles if using a low frequency aerial target it will be seen as a 5.5km tall, 1.6km wide and 200 meter depth target. F-35 is claimed as 1200mph max speed, it covers 20 kms per minute(can use the Su-57 as an example to), And since the Nebo-M is considered a circular scan that gives target updates every 5-10 seconds if its travelling at a speed of 1200 mph pulling a hard left or right 1.66 to 3.33kms. So we can add 3.33km for height and width of the box to 8.83kms by 4.93kms.

https://en.topwar.ru/168498-sistemy-pvo ... k-buk.html "The characteristics of the ARGSN used on the 9M317MA rocket make it possible to capture a target with an EPR of 0,3 m² at a distance of up to 35 km."

35(.0001 ÷ 0.3) ^.25 at a 4.73km distance a .0001m2 target can be tracked with a buk-M3’s missile autonomously by the missile itself. http://www.1728.org/angsize.htm if we assume that the radar beam angle 120 degrees with a 4.73km distance the size of the entire radar beam horizontal angle would be 16.73kms with 8.83kms covered and if the Elevation angle is the same or smaller the 4.93km height can be covered. However the only thing I did not take into account is

1. 9M96MD and 40N6 are not only new missiles with active homing capabilities like the Buk-M3 missile but bigger in size which I assume they will see something smaller and farther than 0.3m2 passed 35kms.

2. Considering the flight ceilings of the 9m96MD and 40N6 it seems that more than half their flights they will be able to fly above the max flight ceilings current aircrafts are capable of. Meaning these host radars will be pointing their radar beams on top of highly reflective topside surface of aircrafts which could be considerable in RCS size compared to pointing a radar beam at the front of an aircraft.

Has this been covered before here using VHF or UHF radars while using just tracking capabilities of the missiles themselves?

https://armadainternational.com/2019/06 ... ng-spears/ the SPEAR-3 covers 8-40ghz does anyone have information on the MALD frequency jamming coverage? I only heard of different EW payloads

F-117.jpg

nebo radars.png


Also since some 5th gen aircraft programs have a long term investment until 2070 how has stealth technology improved to keep up with the emergence of new radar capabilities like in the field of photonics?

КРЭТ - Концерн Радиоэлектронные Технологии news 3768

“for example, take ground-based radar. Today, this radar is the size of a multi-story home, but using microwave photonics, the station can be installed on a standard KAMAZ truck. The effectiveness and range of the radar would be exactly the same, namely thousands of kilometers. Several of these mobile and small radar systems can be networked, which will only increase their characteristics.”

俄罗斯苏57失败板上钉钉?仍有最后一丝希望反败为胜|俄罗斯|战斗机|雷达_新浪军事_新浪网 (sina.com.cn)

"The detection distance is very far, the energy conversion efficiency is up to 60%, the traditional radar is only 30%, and the noise is more than 100 times lower than the traditional radar, greatly improving the signal-to-noise ratio, for stealth target theory detection distance of more than 500 kilometers!"

Фотонные радары, радиофотоника и стелс-технологии (naukatehnika.com)

"Unlike traditional radars, it will not be physically possible to silence ROFAR by traditional means of EW. The dynamic range of the photon crystal is about 200 DB. Modern electronic receiver, for comparison, has a range of 40 - 60 DB, and we modern EW complexes provide a signal to the entrance of the radio receiver - in 70-80 DB relative to its threshold sensitivity. Thus, the device that needs to receive the signal is displayed from a healthy state. Even after the interference in his inside there are still processes that do not allow him to work. But on Earth there is simply no energy source for a signal with a capacity greater than 200 DB, so this logic in the case of ROFAR simply does not work. It can be confused by so-called intellectual opposition, but this is a different story."

Fighter Tempest's New Radar - Collects a City's Worth of Data per Second | IE (interestingengineering.com)

Tempest's radar technology will reportedly provide over 10,000 times more data than current systems. ‘Multi-Function Radio Frequency System’ will deliver a huge amount of data that equals to internet traffic of Edinburgh in a second, comparingly speaking."

В России создан фотонный радар, способный обнаружить любую цель – Новости РуАН (ru-an.info)

Alexey Leonkov, a military expert of the magazine "Arsenal of the Fatherland" told about the revolutionary significance of the development in an interview with the Moscow Komsomolets.

"According to the analyst, the transition from electrons to photons will lead to the creation of a new generation of radars that will be able to process information using the electromagnetic waves of the microwave range. The speed of transmission of information will increase to hundreds of terabits per second, that is, the reflected signal will be processed instantly at all frequencies. Thus, it will be possible to increase the probability of identification of the target to 100%, radars will be able to detect any target. Alexey Leonkov believes it is important that the stations themselves will become smaller, but at the same time it will be much more effective, it will be more difficult for them to put interference. The new radiophoton radars will be 2-4 times smaller than Daryal. In addition, the thermal radiation will also decrease."


United_Kingdom_2020_Forecast_Highlights.pdf (cisco.com)

In the United Kingdom, average IP traffic will reach 23 Tbps in 2020, and busy hour traffic will reach 132 Tbps.

So to keep up with the future of photonic radars does that mean next gen stealth has to have a 100 to 1000fold improvement in stealth reduction on all sides?
 
Last edited:

Dev

ACCESS: Confidential
Joined
Nov 11, 2019
Messages
56
Reaction score
31
And, do you want to know what is the operating frequency of these radars below?. Both in X-band.
The radars you cite are attached missile defense radars. Who are looking through a narrow sector. Narrow in elevation. If a ballistic missile passes through this sector, then escort and guidance radars will look there.
We're talking about surveillance radars, which are supposed to track aerodynamic objects in a wide sector.

As they say in Russia, "You mixed people and horses."

If scan time is absolutely important, nothing stop them from using a fraction of the array for shorter range quick scan and the rest for long range scan, we are in the age of AESA radar after all
By turning off part of the TRM, you will also reduce the area, and therefore the gain. That's what I'm talking about to you.
Only, why make a radar in order to then reduce its area, in such a "wild" way.

I didn't engage in any dispute with them , if you took my advice and opened a book, you will see that free space basic transmission loss and atmospheric attenuation are completely different things. Atmospheric attenuation is caused by the energy absorption of gas and molecules in the atmosphere, if you transmit radio wave in a vaccum, there is no atmospheric attenuation. Free space basic transmission loss is the lost caused by the spread of the radio beam over distance, you still have that even if you transmit radio wave in space vacuum.
In my opinion, I said everything.
You can ferry me over. Suddenly your calculator will miraculously give not 31 dB, but 2 dB.
If you do not like the ITU formula, you can use this one by expressing Pr - the receiver sensitivity.
1610135793897.png
I assure you this formula will give the same result.

There are already more than enough overwhelming evidences. You are just quibbling
The chart given by Wu Jian Qi has number on it, which can be used to deduce the stealth quantity
The comparison by Robert Wallace is straight forward and can be used to deduce the RCS
The charts and reduction percentages from LM slides are very straight forward and can be used to deduce the percentage of RCS reduction
The number given by Michael Hake is straight forward.
All these evidences support the same conclusion.
No figures, no conversation. :D

Secondly, when there is a telephone pole flying at you through the cloud cover at two - three time speed of sound then anyone can make inaccurate estimation, let alone something as small as the different of 50 and 65 degrees.
You can think at least 90 degrees. But Zelko said 50. That's a fact. And I rely on facts, not speculation.

Thirdly, no. The detection was done by the P-18 radar, when the airplane got close, they tried to track it with the fire controlled radar, falling several times before finally acquired a lock and launch missile immediately. And also the aircraft was extremely close to the site, so even a small bank angle can lead to its tail making a 90 degrees with the ground radar
They found it P-15 (not P-18) at the bearing of 195 and range of 23.
P-15, by the way, decimeter band. At a distance of 15 km and a bearing of 210, the command sounded to turn on the missile guidance station (CHR-125). Then, within 10 seconds, they cannot find him СНР-125. And they find it on bearing 240. A salvo on course 250, defeat on course 270.
In any case, they found (CHR-125) from a smaller angle than the rocket arrived.

That actually look quite cheap and inaccurate compared to the kind of model USA used in their RCS test pole
Everything is cheap in Russia! We sleep in the straw and scratch our backs with our teeth.:D

Yes but is there any Russian airplane close by to analyze their RCS and are they tracked on Russian air defense radar?
F-22 on the screen (OLS) of the Su-35 in Syria.
1610138277304.png

The thing is, how did they arrived at these numbers? did they made individual models for each airplane then test?, I don't think they did. And even if they do, what does their model look like?
Probably the same as the Chinese experts.
You have another problem. If you like the figures, you write it down as proof, if you don't like it, then you reject it.

And what does these number mean? average? min? max?
I didn’t understand this document.
And the Chinese experts, what are the numbers for the F-22? Average and minimum?
 

Ronny

ACCESS: Secret
Joined
Jul 20, 2019
Messages
367
Reaction score
145
The radars you cite are attached missile defense radars. Who are looking through a narrow sector. Narrow in elevation. If a ballistic missile passes through this sector, then escort and guidance radars will look there.
We're talking about surveillance radars, which are supposed to track aerodynamic objects in a wide sector.

As they say in Russia, "You mixed people and horses."

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



By turning off part of the TRM, you will also reduce the area, and therefore the gain. That's what I'm talking about to you.
Only, why make a radar in order to then reduce its area, in such a "wild" way.
You don't turn off part of the TRM, you can divide the array into subgroup that perform multi tasks. For example: target at high elevation only at very close range, so you only need very small array sub group for that, while for long range, the majority of the array can be used.




In my opinion, I said everything.
You can ferry me over. Suddenly your calculator will miraculously give not 31 dB, but 2 dB.
If you do not like the ITU formula, you can use this one by expressing Pr - the receiver sensitivity.
View attachment 648125
I assure you this formula will give the same result.
Once again.
Firstly, you are still confusing between the free space path loss and atmospheric attenuation. They are completely different things as I already taught you earlier. free space path loss is very significant because it is the spread of signal density and you will have it even if you transmit in a vacuum. Atmospheric attenuation is the absorption of atmosphere and very small for frequency like X band and lower, it also doesn't exist in a vacuum.
Secondly, I already used the Dmax formula for the calculation that I gave you earlier.


No figures, no conversation. :D
And you were given figures and official source, you basically just quibbling


You can think at least 90 degrees. But Zelko said 50. That's a fact. And I rely on facts, not speculation.
And your so called "fact" is based on a guy speculating with his naked eye when he was attacked by a missile at night ;)

They found it P-15 (not P-18) at the bearing of 195 and range of 23.
P-15, by the way, decimeter band. At a distance of 15 km and a bearing of 210, the command sounded to turn on the missile guidance station (CHR-125). Then, within 10 seconds, they cannot find him СНР-125. And they find it on bearing 240. A salvo on course 250, defeat on course 270.
In any case, they found (CHR-125) from a smaller angle than the rocket arrived.
Nope, it was P-18. I have the presentation given by Zoltan Dani himself
zoltan Dani.PNG


F-22 on the screen (OLS) of the Su-35 in Syria.
View attachment 648128
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 ;)
Capture.PNG


Probably the same as the Chinese experts. You have another problem. If you like the figures, you write it down as proof, if you don't like it, then you reject it.
I didn’t understand this document.
And the Chinese experts, what are the numbers for the F-22? Average and minimum?
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. 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. Whereas in case of Ukrainian experts, they only given a generic value, since they aren't the one who made the fighter, how they get the value is important.
 

quellish

I am not actually here.
Senior Member
Joined
Aug 6, 2007
Messages
2,173
Reaction score
203
I mean, any computer simulation does not give high-quality results.

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.

Scaled testing in chambers and full scale testing on outdoor RCS ranges is used to *validate and refine* the computational electromagnetics model. If the prediction does not match the measurement you go back and work on it until it does! That's the secret, and how the prediction gives high quality results.
This is exactly what some of the strange shapes seen at outdoor RCS ranges are for. Validating computational models with measurements.

That said, all we have to do is find a way to make airplanes out of whatever those cables at Tver are made from and we'll be invisible!
 

tequilashooter

ACCESS: Confidential
Joined
Jan 2, 2021
Messages
73
Reaction score
37
Since you guys like talking about stealth so much I got something for you guys. Although I think this might be important for later gen stealth.


Российские учёные создали уникальный метаматериал со свойствами "стелс" (vegchel.ru)

In the authoritative scientific journal Physical Review there was an article sponsored by Russian scientists from the NITU "MISIS" in Moscow. The article talks about the development of a unique metamaterial, among the many amazing properties of which and the ability to remain "invisible" for a whole range of electromagnetic radiation. Such metamaterial can reportedly be used in the creation of technology with unique stealth technologies (new stealth variants).

It is known that not only physicists from Moscow are involved in the creation of the technology, but also Greek scientists from the University of Crete. It should be noted that the work was carried out within the framework of Russian-Greek cooperation in the field of quantum technologies. The relevant contract was concluded in 2016. The cooperation is financed by both countries (RF and Greece) and provides for the creation of these metamaterials.

For reference: metamaterials - materials created artificially. They have a heterogeneous internal structure that allows the electromagnetic wave to be lost inside such a material. This can allow the use of metamaterials as a kind of "invisible cap" for modern combat vehicles. It is reported that metamaterials can be suitable for the creation of promising computing and communication systems with photonic principles rather than electric ones."

The experimental part of our study is the created unique metamaterial, which is a small flat lattice of so-called metamolecules, cut laser sharp from a single piece of ordinary steel. By adding a non-linear semiconductor, the metamater will become a reconfigurable screen for STELS technology, a set of ways to reduce the radar visibility of combat vehicles in radio, infrared and other areas of the spectrum.

Scientists create stealth technology that hides metal masts and antennas completely (sciencex.com)

Elongated metal objects like antennas or cell towers have an electric response—a signal that appears in response to an impact. To hide such an object from radar, the object must scatter light, like an object with a magnetic response, which is very weak. This was accomplished by scientists from the Russian-Italian scientific collaboration, in the framework of the "ANASTASIA" project (Advanced Non-radiating Architectures Scattering Tenuously And Sustaining Invisible Anapoles), named after the Grand Duchess of the Russian Empire Anastasia Romanova.

"We came up with a special coating based on an ideal magnetic dipole scatterer that turns an elongated metal object with an electric response into an object with a magnetic response," said one of the researchers, associate professor at the NUST MISIS Superconducting Metamaterials Laboratory, Alexey Basharin. "This has become possible due to the anapole state of the coating material, which lowers the electric type scattering to the level of the magnetic one and even lower. As a result, the object becomes invisible."

The first of the possible applications of the new coating will be Stealth technology for military and civilian purposes—to hide various elongated objects, such as aircraft landing gear, antennas and various sensors, ship masts and airport towers. The developers emphasize, that if the task of hiding these objects from enemy radars is trivial, the task of electromagnetic compatibility of antennas on satellites is vital: antennas must not affect each other. And this will be possible only if they are invisible.

Metamaterial Can Change Optical Properties, Become Invisible or Reflective in IR Spectrum | Research & Technology | May 2020 | Photonics.com

ST. PETERSBURG, Russia, May 21, 2020 — Researchers at ITMO University and the University of Exeter have developed a metamaterial capable of changing its optical properties without any mechanical input. The new metamaterial could improve the reliability of complex optical devices while also making them cheaper to manufacture.

Thanks to their complex periodical structure, metamaterials are relatively independent from the properties of their components. Such structures can be volumetric or flat, as is the case with metasurfaces.

“Metasurfaces allow us to achieve many interesting effects in the manipulation of light,” ITMO researcher Ivan Sinev said. “But these metasurfaces have one issue: How they interact with light is decided right in the moment when we design their structure. When creating devices for practical use, we would like to be able to control these properties not only at the outset, but during use, as well.”


I hope the road to metamaterials improve to the point that its stealth signature would surpass reflect away designs and material absorption later. Don't care if that kills all the fun in aviation forums discussing the Su-57 :p
 
Top