Intake design and general stealth discussions

[stealthflanker]

Data taken from tutorial. Not a journalistic article.

Is it possible to say where does this come from or how "official" it is?

Here is a sheet from the S-200D manual.

What's the date of the manual ? I guess it's somewhere in 1989 or 1990's.

 

[overscan (PaulMM)]

It's before the ATF became F-22, so its older than 1991. Given its age, it's purely guesswork.

 

[Dev]

What's the date of the manual ? I guess it's somewhere in 1989 or 1990's.

1991. But the RCS value did not change significantly in 2000.

 

[tequilashooter]

PE-MIMO has better spatial resolution but also has much shorter range.

Sarlio_Siintola_Tammilehto.pdf (theseus.fi)


Documents download module (europa.eu)




The spatial resolution isn't that bad, if not better than before. I am definitely going to lookout for this particular radar Радиолокационная станция "Яхрома" в Крыму будет работать в четырех диапазонах - Армия и ОПК - ТАСС (tass.ru)

"The newest radar station "Yakhroma", the construction of which in Crimea was announced by the Minister of Defense of the Russian Federation Sergei Shoigu at the annual board of the Ministry of Defense, will operate in four ranges with a view of 270 degrees. A source in the military-industrial complex told TASS about it.

"This station has no analogues, it will operate in four bands: meter, centimeter, decimeter and millimeter," the agency's interlocutor said, specifying that the station's view would be 270 degrees.

In December 2020, during the final collegium of the military department, Russian Defense Minister General of the Army Sergei Shoigu announced that the construction of the newest Yakhroma radar station in Sevastopol would begin in 2021."

Do not want to declare it as a photonic radar just yet because of wide usage of bands, but something to look out for later.

 

[Ronny]

When did LM officially announce these numbers (F-22 or F-35)?

They repeated these number several times

And I do not force you to believe.

I just point out how laughable these value are.

There is efficiency. At least because of poorly working in the long-wavelength range of radio-absorbing coatings on the aircraft. But they are not a panacea.

Firstly, there is no efficiency because the power density of VHF is much lower so a 5 fold increase in RCS is simply not enough for its to have detection range advantage over X band.
Secondly, magnetic RAM has decent absorbing capability in low frequency while still relative thin

And what should hinder this? Beliefs? Stealth has its effect, even in a fivefold decrease / increase in power. And reducing the distance by 1.5 times. I described to you above why it won't work! Radars are a compromise. It is impossible to increase all the characteristics without reducing others. This is life and the laws of nature

And your explanation is so obviously wrong
Firstly, what do you think the attenuation rate of X-band in the atmosphere is?. At 10Ghz, it is less than 0.01 dB/km, so for 400 km, it is only about 4 dB


Compare that to the different between the power density of X-band and VHF band radar of the same size. Gain is inversely proportional to wavelength, so by increase wavelength by 400 times, you will lose a lot more from the reduction in power density than you would gain from the tiny 5 fold increase in RCS and the 4 dB from reduction of atmosphere absorption. In other words, there would be no reason to use VHF radar against stealth aircraft if the RCS increase is only 5 times like you said. Normally, VHF radar have much worse accuracy, power density than X-band but it has advantage in the much higher RCS of target in that band. That the trade off. But if the value is just like you claimed, then VHF radar is worse in all ways

 

[Ronny]

Data taken from tutorial. Not a journalistic article.

Is it possible to say where does this come from or how "official" it is?

Here is a sheet from the S-200D manual.

That sheet is even before F-22 made its first flight, so they can't even know F-22 correct shape, let alone the type of RAM it use. Unless they have some sort of time machine to go back in time that sheet is even worse than amateur's analysis

 

[Ronny]

PE-MIMO has better spatial resolution but also has much shorter range.

Sarlio_Siintola_Tammilehto.pdf (theseus.fi)
Documents download module (europa.eu)
The spatial resolution isn't that bad, if not better than before. I am definitely going to lookout for this particular radar
Do not want to declare it as a photonic radar just yet because of wide usage of bands, but something to look out for later.

I don't think you should be too hang up on the PEMIMO radar, it just a small complement short range system

 

[tequilashooter]

I don't think you should be too hang up on the PEMIMO radar, it just a small complement short range system

Oh no worries here, anything that beats a 40-50 km spatial resolution diameter is fine with me and gives me something to look forward to.

 

[Ronny]

Oh no worries here, anything that beats a 40-50 km spatial resolution diameter is fine with me and gives me something to look forward to.

the spatial resolution is range dependent, for Ranger project, 800 meter resolution is for 125 nm for 600*30 meter receiving array

 

[tequilashooter]

Correct.

 

[Dev]

Они повторили это число несколько раз

This number is repeated several times by the journalist David Fulghum. LM officials have never given these numbers.

Compare that to the different between the power density of X-band and VHF band radar of the same size.

There is a radar station measuring 12 m and a wavelength of 1.1 m.
65 * 1.1 / 12 = 6 degrees.
For example, the scaning of the sector is 60 * 60 degrees, the radar does it in 10 s.
(60 * 60) / (6 * 6) = 100 steps.
Let's reduce the wavelength to 3 cm.
65 * 0.03 / 12 = 0.1625 degrees.
(60 * 60) / (0.1625 * 0.1625) = 136 331 steps.
That is, your invented radar station will indeed have a large Gain! But, just to scan the standard sector 60 * 60, it will be within (136 331/100) * 10 = 13 633 seconds or 3.7 hours.

I just point out how laughable these value are.

As I see it, we moved to the "area of faith", from the "area of facts and documents." But I'm not interested in that. If you want to believe the journalists, I don't mind.

 

[Dev]

year 2000. Almaz design bureau.
Based on these data, an assessment and further ways of modernizing the S-125 Pechera were carried out.

Spoiler: +

Source

Персональный сайт по истории пво - Главная страница

Believe the journalists or not, everyone decides for himself.

 

[Ronny]

This number is repeated several times by the journalist David Fulghum. LM officials have never given these numbers.

Did you follow the program at all?

There is a radar station measuring 12 m and a wavelength of 1.1 m.
65 * 1.1 / 12 = 6 degrees.
For example, the scaning of the sector is 60 * 60 degrees, the radar does it in 10 s.
(60 * 60) / (6 * 6) = 100 steps.
Let's reduce the wavelength to 3 cm.
65 * 0.03 / 12 = 0.1625 degrees.
(60 * 60) / (0.1625 * 0.1625) = 136 331 steps.
That is, your invented radar station will indeed have a large Gain! But, just to scan the standard sector 60 * 60, it will be within (136 331/100) * 10 = 13 633 seconds or 3.7 hours.

Funny that you talk about scan time, but the advertised quantity of VHF radar over X-band against stealth aircraft has always been much better detection range. But if what you claimed about the RCS was true then literally, VHF radar will be much worse than X-band radar against stealth aircraft
And, if you use X-band radar, you also don't even need a 12*12 meters radar, the only reason for the huge aperture of VHF is their terrible gain

As I see it, we moved to the "area of faith", from the "area of facts and documents."

Believing that Russian can somehow magically know the exact future RCS of the F-22 before its shape even finished and 6 years before it flew the first flight clearly will require a lot of faith. Neverminded the huge contradictory with anechoic chamber measurement

 

[Dev]

Did you even followed the program at all?

I am not interested in journalistic articles about "balls" and "peas". Please provide official figures from LM, Department of Defense or related organizations. That's exactly what you promised.

And frankly, if you use X-band radar, you also don't even need a 12*12 meters radar

You have set this condition. I just showed you how obscene your statements look from the side of scan time.

the only reason for the huge aperture of VHF is their terrible gain

A large dimension is needed to make the beam reasonably narrow for scanning a space with a given resolution for a specified time. Naturally, the longer the wavelength, the larger the antenna size will be required. And naturally, this also affects the gain. Therefore, as the gain increases, the scan time will decrease.

Believing that Russian can somehow magically know the exact future RCS of the F-22 before its shape even finished and 6 years before it flew the first flight clearly will require a lot of faith. Neverminded the huge contradictory with anechoic chamber measurement

You were provided with documents from different years (1991 - ATF to 2001 - F-22)
You were given a quote from Davidenko (on the first page) of the general designer of the UAC - 2010.
I can also quote Poghosyan (Head of the UAC) from an article on stealth technologies - 2003
In all of them the figure is 0.1 - 0.5 m2.

You, besides "balls", "peas" and articles of journalists, cannot cite anything.

Indeed, these are questions of faith. So I shut up.

 

[Ronny]

Did you even followed the program at all?

I am not interested in journalistic articles about "balls" and "peas". Please provide official figures from LM, Department of Defense or related organizations. That's exactly what you promised.

Nice try but that isn't a comment from the journalist. Quite a stealthy attempt (pun intended) of you trying to paint the comment from Robert Wallace the senior manager for F-35 flight operation and the ATF requirements as journalistic.

You have set this condition. I just showed you how obscene your statements look from the side of scan time

Except you forget that VHF radar must be big because they must have enough gain for their radar beam to have at least some utility otherwise with small aperture then their beam is quite omidirectional but X-band radar doesn't need that, you can get quite focused beam even with relatively small aperture. But the thing is, if the X band RCS value of stealth aircraft is actually as high as you claimed, and the VHF RCS is only 5 times bigger than the X band value. There would be no use for anything like Nebo , JY-27 whatsoever, because they can easily build small X-band radar 1*1 m or 2*2 m that is not only have extremely long range against stealth aircraft, but also have very quick scan time.
Secondly, you seem to very conventionally forget the common stealth detection range advantage of VHF radar over X-band. I'm not asking you about scan rate, I'm asking you: " if RCS in VHF band is only 5 times better than in X-band, then what the point of VHF radar against stealth aircraft? How can VHF radar detect stealth aircraft from greater range?.

You were provided with documents from different years (1991 - ATF to 2001 - F-22)
You were given a quote from Davidenko (on the first page) of the general designer of the UAC - 2010.
I can also quote Poghosyan (Head of the UAC) from an article on stealth technologies - 2003
In all of them the figure is 0.1 - 0.5 m2.

You, besides "balls", "peas" and articles of journalists, cannot cite anything.

Indeed, these are questions of faith. So I shut up.

I love the double standard you are pulling here
When I gave you quote from Robert Wallace, you very quickly try to pass it off as journalistic articles, but you have no problem quote Davidenko and Poghosyan eventhough, their quote are also on articles of some sort
When I gave actual anechoic chamber measurement of F-117 metal model, you comment that it isn't accurate but yet you have no issue believe the Soviet guesstimate of F-22 RCS even though that guesstimate was done before F-22 finalize its shape and 6 years before it made the first flight.
In addition, you also lied. I didn't just gave you citation of article, I also gave data from varius radar scattering simulation and even one actual chamber measurement as well as one detection range graph given by Wu Jian Qi, the chief engineer of the CETC group

 

[Dev]

Когда я приводил вам цитату Роберта Уоллеса, вы очень быстро пытаетесь выдать ее за журналистские статьи, но у вас нет проблем, цитируя Давиденко и Погосяна, хотя их цитата тоже есть в каких-то статьях.

Роберт Уоллес привел какие-то цифры ? RCS измеряется в м2, дБсм и т. Д. Я дал вам цифры , вы - шары, горошины и камешки. Абстракции, которые можно трактовать как угодно, мне не интересны.

Когда я дал фактическое измерение в безэховой камере металлической модели F-117, вы отметили, что это неточно, но все же у вас нет проблем верить советской оценке F-22 RCS, хотя эта оценка была сделана до того, как F-22 завершил свою форму. и за 6 лет до своего первого полета.

В документе на С-200 от 1991 г. фигурирует ATF, что соответствует времени первого полета YF-22 (программа ATF - 29 сентября 1990 г.).
Остальные документы и заявления относятся к 2000, 2003, 2010 гг., Когда F-22 уже совершил свой первый полет (7 сентября 1997 г.).
Не вводите читателей в заблуждение.

 

[LMFS]

@Ronny:

this is the kind of backlash sadly to be expected when Western narrative is applied by which Russians are automatically suspect of being backwards and liars. It would be much better if we just express our opinions from the position of admitting that we do not have facts, that is, real RCS measurements needed to settle the dispute. We just have shown some examples of questionable statements by US MIC which some people still take great efforts to defend, despite a long history of those guys being anything but saints.

> The claimed RCS for F-22 is on the level of any of the hundreds of weak scattering sources any fuselage has, so it is unreasonably low.
> F-117 downed, VLO RQ-170 detected and landed on Iran, 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?
> 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.

I respect your opinion so don't take this as yet another attempt to convince you, just as a final remark from my side for you to hopefully understand a bit better my (our?) position.

 

[stealthflanker]

Well, it's very hard, considering nobody settle on what standard to use in the first place like, what RCS value to use (Average vs "1 side") Or even Frequency.

Measure of "average" is also very vague. Centimetric wave band correspond to old IEEE System which covers S-band down to K band, so if there is figure of "0.1-0.5" sqm in "centimetric wave band" Does that mean the RCS is 0.1 in S-band and 0.5 sqm in K band ?.

 

[Scar]

their quote are also on articles of some sort

The science review "FUNDAMENTAL AND APPLIED PROBLEMS OF STEALTH TECHNOLOGIES" Pogosyan wrote in collaboration with the Director of the Institute of Theoretical and Applied Electrodynamics of the Joint Institute for High Temperatures of the Russian Academy of Sciences Andrey Lagarkov and presented at a meeting to the Presidium of the Russian Academy of Sciences is hardly may be called a journalistic article.

VIVOS VOCO: А.Н. Лагарьков, М.А. Погосян, "ФУНДАМЕНТАЛЬНЫЕ И ПРИКЛАДНЫЕ ПРОБЛЕМЫ СТЕЛС-ТЕХНОЛОГИЙ"

 

[Dev]

Based on these data, an assessment and further ways of modernizing the S-125 Pechera were carried out.

Some more.
Data for assessment, heading parameter 0 (target flies to the radar).
Why are there two band in the table?
СНР-125 operates in the centimeter band (8.9-9.46 GHz).
Also, for early detection, the P-15 of the decimeter band (810-950 MHz) is attached.

So, the RCS data (0.1m2 for F-22) in the table can be viewed for these bands and from the front side of the aircraft.

 

[tequilashooter]

@Ronny

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwiQ1cDd6IfuAhV6GFkFHQxtBnQQFjABegQIBBAC&url=https%3A%2F%2Fwww.sto.nato.int%2Fpublications%2FSTO%2520Meeting%2520Proceedings%2FRTO-MP-SET-080%2FMP-SET-080-25.pdf&usg=AOvVaw0CKf7Q9K101O6ktDu3Umld

At most they can classify aircrafts and helicopters Countries integrating Over-The-Horizon (OTH) radars into air defence networks to detect and track stealth Aircrafts, Aircraft carriers and hypersonic missiles | International Defense Security & Technology Inc. (idstch.com)

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

I wonder if that magical crystal in their photonics research team has anything to do with Russia's magical crystal doing these that I have recently found.



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."

They also claimed like 1hz to 100ghz with the photonic radar in which their 4 band radar is unheard of until now, Than RTI states in 2020 that in 5 years a sub-millimeter radar detection for drones which basically tells me 300ghz+. Only credibility of those very high HF detection capabilities is that somewhere in this year they will use a 10 meter corridor monitoring civilians in a airport to see if they have any items like weapons. I think its could to at least know where the future is heading. This is officially my last post on OTH radars RCS classification, you seem to be having a handful here already.

 

[Ronny]

Роберт Уоллес привел какие-то цифры ? RCS измеряется в м2, дБсм и т. Д. Я дал вам цифры , вы - шары, горошины и камешки. Абстракции, которые можно трактовать как угодно, мне не интересны.

Firstly, there isn't many way to interpret the golf ball, marble. The reason they often used that analogy is because a ball have same RCS from all direction, and therefore easy to grasp
Secondly, Lockheed Martin give the exact amount of detection range reduction due to stealth many times, so it is quite clear and easy to work out the RCS

В документе на С-200 от 1991 г. фигурирует ATF, что соответствует времени первого полета YF-22 (программа ATF - 29 сентября 1990 г.).
Остальные документы и заявления относятся к 2000, 2003, 2010 гг., Когда F-22 уже совершил свой первый полет (7 сентября 1997 г.).
Не вводите читателей в заблуждение.

You know there was the YF-23 competing with the YF-22 for the ATF program right?. And the YF-22 also changed a lot when it become F-22.
So not only that data is purely speculation, it also made at the time the actual F-22 didn't even take shape yet.

 

[Ronny]

The science review "FUNDAMENTAL AND APPLIED PROBLEMS OF STEALTH TECHNOLOGIES" Pogosyan wrote in collaboration with the Director of the Institute of Theoretical and Applied Electrodynamics of the Joint Institute for High Temperatures of the Russian Academy of Sciences Andrey Lagarkov and presented at a meeting to the Presidium of the Russian Academy of Sciences is hardly may be called a journalistic article.

VIVOS VOCO: А.Н. Лагарьков, М.А. Погосян, "ФУНДАМЕНТАЛЬНЫЕ И ПРИКЛАДНЫЕ ПРОБЛЕМЫ СТЕЛС-ТЕХНОЛОГИЙ"

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.
There are plenty of official sources that reference much lower RCS value for stealth aircraft.
For example:

 

[tequilashooter]

Radar cross section: The measure of stealth - Military Embedded Systems

"We didn’t discuss long range bomber aircraft in the previous article, but it’s worth throwing those values in here for your reading enjoyment. The B-52 has an RCS of about 100m2. The B-1 bomber is 10m2. The B-2 bomber has an RCS of 0.0001m2, the same as the F-22, the size of a bumble bee. The new B-21 bomber, now being built by Northrop Grumman, is virtually invisible to UHF/VHF radar. It shows up about the size of a mosquito. I am forced to use one formula and do the calculations here, since the return signal is -70db for the B-21, and the RCS in square meters was not on the web anywhere: RCSsm=10db/10 = 10-70/10 = 10-7, or about 0.000001m2. If you ever wondered about it, that’s the size of a mosquito on radar."

 

[Dev]

Firstly, there isn't many way to interpret the golf ball, marble. The reason they often used that analogy is because a ball have same RCS from all direction, and therefore easy to grasp

I am not interested in the interpretation of abstract objects. That is why they are abstract, that everyone can interpret them in their own way.
I did not see the numbers in your next screenshot.

So not only that data is purely speculation, it also made at the time the actual F-22 didn't even take shape yet.

In 2000-2003, the shape has not yet been determined?

 

[tequilashooter]

Man I saw the view count after Ronny's response rise to like 14 viewers after 3-5 minutes than after my post 3-5 minutes the viewers dropped to like 5. I am sorry but are there people taking this thread seriously? It reminds me of that 2016 presidential debate where there were like some old women taking the debate seriously writing notes and stuff outside while I was drunk laughing outside watching one of debates with my friends mocking both candidates, than I looked over back at them and they gave me these scolding looks.

FLASHBACK: Back to the Future: The Resurgence of the Flying Wing in the 21st Century > Robins Air Force Base > Article Display (af.mil)

"Northrop constructed the B-2 with materials such as carbon-fiber composite plastics and covered the aircraft with an anti-thermal coating to absorb acoustic, infrared, visual and radar signatures, which greatly reduced the possibility of being identified by various types of detection systems. According to the Air Force in 1990, the RCS of the B-2 is the size of an insect"

We got supposed sources "from experts" saying .01 and .0001m2 all over the place for the B-2. If this is suppose to be a serious thread on stealth RCS than carry on you guys.

 

[Ronny]

@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


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.

 

[Dev]

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.

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
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.

 

[Dev]

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

 

[Dev]

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.


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).


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.

 

[LMFS]

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...

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.

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.

 

[tequilashooter]

@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]

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.

 

[Ronny]

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:




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

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



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



Btw, I posted this as well:

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

 

[Ronny]

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]

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

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




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.

https://www.amazon.com/s?i=stripbooks&rh=p_27%3AClayton+K.+S+Chun&s=relevancerank&qid=1610025760&text=Clayton+K.+S+Chun&ref=sr_pg_1

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.

Впервые для печати: как сербам удалось сбить американский самолет-невидимку

Впервые для печати: как сербам удалось сбить американский самолет-невидимку

www.svoboda.org

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.

 

[LMFS]

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.

 

[tequilashooter]

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.

 

[tanino_it]

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]

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.