Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: artik on May 13, 2014, 02:48:58 AM
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We all are talking about 5th generation fighters how they are stealthy...
Stealth:
- They are costly (F-22, F-35, B-2)
- Not really available - currently only few F-22, B-2 operational around + several stealthy drone models.
- Not 100% fault proof - long wave radars, IR emission, visual detection and so on that most likely being developed and less known
Now as cheaper alternative we can use ECM... Missile heads usually have simpler and less powerful radars and easier to fool - so if you know how, you generally can. So:
ECM:
- Much cheaper - just a smart computerized pod
- Can be easily upgraded for new threats (new pod or even software upgrade)
- Do not require significant changes in the aircraft, if at all
- Almost no impact on the flight characteristics (besides some drag)
- Can be installed almost on any aircraft
- Most likely get you to the merge - eliminating all stealth advantages of the opponent
Even Russia, that has traditionally less efficient avionics and electronic system produces and exports ECM pods that (at least according to the specs) handles AMRAAM missiles.
So what is more effective*:
- Have few stealthy drones/aircraft for special missions and sophisticated ECM on 4th++ generation aircraft
- Invest into stealthy air force
* By effective I mean - having the most effective air force for a given budget constraint
Some samples:
MiG-29K with IAI ECM Pod: https://www.youtube.com/watch?v=NhN7_L3R6uU#t=450
MiG-21 Bison Carrying an IAI ECM Pod.
(http://vayu-sena.indianmilitaryhistory.org/pix/mig21bison-2771-01.jpg)
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ECM also broadcasts your position to everyone with even the most rudimentary EW units. ECM is something you use after you have been detected. Stealth prevents detection. The Russian R-27 and newer missiles as well as the Sparrow and AMRAAM has home-on-jam capabilities.
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ECM also broadcasts your position to everyone with even the most rudimentary EW units. ECM is something you use after you have been detected. Stealth prevents detection. The Russian R-27 and newer missiles as well as the Sparrow and AMRAAM has home-on-jam capabilities.
Stealth DELAYS detection or reduces signature. It is not a panacea.
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artik,
ECM is only as good as the knowledge of the threat it is designed to defeat. If you know the enemy radar very well, you can tailor sophisticated methods to fool it completely. In reality, one side is building the radar and its opponent build the ECM. The latter does not posses perfect knowledge of the radar system, though that is not always true.
ECM and ECCM (i.e. methods to defeat ECM) evolve very fast, so effectiveness is a big unknown and may change all the time. ECM capabilities are closely held secrets. Actually one of the most secret pieces of equipment on the plane. In addition, there is ECM support from the ground and other planes on special EW missions. The latter two can often defeat radars by brute force - that is by very high power transmission that blinds enemy radars. It's the equivalent of shining a spotlight into your eyes. This will work on any radar given sufficient power concentrated in the right frequencies and the right direction. More elegant and sophisticated methods are preferred though. However, such support is not always available, especially not in deep strategic strikes. For such missions self-ECM and stealth will have to do.
In 1973 the IAF took a beating from the soviet SAMs employed by the Syrians and Egyptians. American ECM pods that the US used in Vietnam were handed over to the IAF but proved to be worthless. Israel decided to develop its own EW capabilities and 10 years later the IAF destroyed over 20 Syrian SAM batteries without losing a single plane, clearing the whole Lebanon airspace from SAM threat for the rest of the war. IAF conducted several operations in Syrian airspace in the time since, and the Syrian SAMs and radars were ineffective during all of them. IAF still installs its own ECM and EW systems in the American planes it gets, much to the dismay of some US companies. With the F35 IAF was promised that it will get planes ready to receive its custom Israeli avionics and systems right off the production line, but I heard talks that the US will again force the IAF to get them with the US systems installed, probably in the hope that the IAF will deem it too expensive to rip out the originals and install the custom ones.
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To avoid being targeted in a Tank you have both IR defeating systems.and also chaff-like dispensers making radar lock almost impossible.
The anti IR systems are quite new.
http://defensetech.org/2011/09/06/bae-developing-ir-cloaking-device/ (http://defensetech.org/2011/09/06/bae-developing-ir-cloaking-device/)
http://www.bbc.co.uk/news/technology-14788009 (http://www.bbc.co.uk/news/technology-14788009)
To be able to knock them out in the future, you need better optical recognition systems, or better radar.
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3 words. HOME ON JAM. ECM not all that its cracked up to be really
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3 words. HOME ON JAM.
4 words. What does that mean?
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4 words. What does that mean?
Missile that is homing on ECM Radiation... but I assume it works mostly on stupid ECM.
ECM is only as good as the knowledge of the threat it is designed to defeat.
Probably the hardest point about it is that most of the data about ECM and radars is highly classified. On the other hand the physics is well known...
So I'm not 100% sure about that statement - finally radar has very well known properties and physics - there maybe some algorithms that try to filter ECM signals. We would probably never know what kind of threats can and cannot be defeated until the real life applications.
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3 words. HOME ON JAM. ECM not all that its cracked up to be really
One important point: Jamming (i.e. creating lots of noise on the relevant frequencies so the signal is get lost) is one of the types of ECM - usually most primitive one. Modern ECM jeopardises the radars by creating false signals or interfering with the original returned signal such that the missile or radar become fooled rather than disabled
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Advanced ECM can fool the radar range, but not the bearing or elevation. Advanced fighter ECM only break STT track on radars that are targeting them, and even then they can deal with a limited number of radars at the same time (which is why they wouldn't be jamming radars in search mode). Bearing/elevation is all a missile needs to track.
From the AIM-120 AMRAAM Operations Guide:
"If at any point during the missile's time-of-flight the target starts to use electronic counter-measures (ECM) the AIM-120B can switch its tracking mode to home-on-jam. When this occurs the AIM-120B homes in on the location of the jamming signal, guiding it to the point where the onboard radar 'burns through' the jamming and re-acquires the radar. When in the home-on-jam mode the AIM-120B interlaces the active pulses of the radar with passive guidance from the home-on-jam equipment."
All the modern Russian BVR missiles also have this capability (and French, British, Chinese etc...)
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Advanced ECM can fool the radar range, but not the bearing or elevation. Advanced fighter ECM only break STT track on radars that are targeting them, and even then they can deal with a limited number of radars at the same time (which is why they wouldn't be jamming radars in search mode). Bearing/elevation is all a missile needs to track.
Not exactly and I'll explain why.
1. The angular resolution of a radar is quite low - especially of small radars that can only have very few elements in the planar array.
2. The signal that is sent and received by the radar comes from many directions (however with different strength)
(http://upload.wikimedia.org/wikipedia/commons/thumb/7/74/Sidelobes_en.svg/200px-Sidelobes_en.svg.png)
3. The signal that radar receives is proportional to 1/r^4 while the signal recorded by the ECM is 1/r^2
Now consider the radar shoots a pulse while scanning to a slightly different direction, ECM can intercept that signal and send (stronger signal) with an appropriate timing - such that even an antenna that looks onto an entire different location would receive a signal that can spoof it, giving it false direction and false speed.
That what modern DRFM systems do.
If at any point during the missile's time-of-flight the target starts to use electronic counter-measures (ECM) the AIM-120B can switch its tracking mode to home-on-jam
There is a difference between Jamming and Spoofing.
Jam - is brute force lets send a strong signal that makes SNR so low that you can't determinate what is the signal - now I can go to the direction of the noise.
Spoofing is creating smart false signals - much harder - but when works much more efficient.
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That is true for small phased array radars, however you'd need very detailed information on the radar to fool it.
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That is true for small phased array radars, however you'd need very detailed information on the radar to fool it.
For example like a radar of AMRAAM, R-77 or (name other radar missile there) and so on. :D
But it is also known to work well on much bigger and stronger radars...
It isn't only about it size. The DRFM is much more complex than just "jamming"
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Nope, they have more conventionally gimballed pulse-doppler radars.
(http://www.ausairpower.net/USAF/000-AIM-120A-1S.jpg)
(http://www.ausairpower.net/VVS/Agat-9B-1103M-150-AS.jpg)
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Nope, they have more conventionally gimballed pulse-doppler radars.
It looks like a simple small planar array radar - which is even simpler :)
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Simple, but it works. They only need to track one single target you know ;)
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Simple, but it works. They only need to track one single target you know ;)
and only one target needs to make it lose track... ;)
There is a difference between Jamming and Spoofing.
Jam - is brute force lets send a strong signal that makes SNR so low that you can't determinate what is the signal - now I can go to the direction of the noise.
Spoofing is creating smart false signals - much harder - but when works much more efficient.
artik is generally correct, though jamming does not have to be a brute force noise screen, it can also mean fooling or confusing the radar to make it lose/ignore/miss the target. Spoofing is about creating false targets so instead of a target, the radar sees 50 targets. I'll just add that jamming and spoofing are the basic categories, each can be achieved in various ways to achieve various ends. Especially against tracking radars that need to predict the position of the target for the next beam it is possible to do some creative things. "Lock on Jam" will not work on the more sophisticated techniques.
Regarding the original debate - stealth is an all or nothing deal and carries a hefty price tag (both in design constraints and in actual $$). When the battle closes to under 10 miles, stealth is right out the window. ECM has a lot of gray in the sense that it can be effective at various levels. ECM is a lot simpler to install on the plane, enforce little design constraints, is a lot cheaper and can be upgraded. ECM is still useful even under 10 miles. Of course, nothing prevents a stealth plane from using ECM as well...
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... Of course, nothing prevents a stealth plane from using ECM as well...
One of the reasons IAF required an ability to install their own ECM to F-35 despite clear resistance from Lockheed Martin.
(To be honest I have a feeling that once IAF receives F-35 it would replace half of LM avionics with its own and add many-many customized features to it)
One of the things I've read about F-117, one of the reasons F-117 was retired is due to fact that it related on stealth only for its protection remaining very vulnerable to other types of threats (like long wave radars that can be easily spoofed with ECM) of course the real reason would probably be known in some not so near future if at all.
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One of the reasons IAF required an ability to install their own ECM to F-35 despite clear resistance from Lockheed Martin.
(To be honest I have a feeling that once IAF receives F-35 it would replace half of LM avionics with its own and add many-many customized features to it)
There are issues with that. One of the main reasons that IAF and the israeli industries got excited about the F35 is that the IAF is supposed to get his custom version of the F35, where many Israeli systems will be installed, or be ready for local installation right off of the production line. For the Israeli industries this is also an opportunity to sell some of their stuff to other foreign F35 buyers. There were lots of fears that the US industries will block custom components and indeed this seems to start happening.
Better stop here because if I speak my mind about the business models of US defense industries this will get me banned fast.
I didn't know the F117 was retired... Never liked that plane.
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I didn't know the F117 was retired... Never liked that plane.
It was retired cause after a 27 year service life it would have cost to much to maintain and operate. It tooks tons of $$ to keep them flying we didnt want to spend while next Gen stealth was being developed. Why spend the money on the "old" F117 when you are fielding F35s that are far more capable and have 1/3 the RCS?
The F117 and its highly accurate weapons scared the bejeezuz out of more then the Iraqis in Gulf 1. This airplane entered some of the most heavily defended air space in the world and took out whatever targets it wanted, and did so without a Loss. The Russian and Chinese watched in Horror and had to direct, and redirect, vast amounts of their wealth both to try and counter the threat it presented and to try and produce their own. That is the Legacy of the F117. A simple bomb dropper that changed warfare forever.
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It was retired cause after a 27 year service life it would have cost to much to maintain and operate. It tooks tons of $$ to keep them flying we didnt want to spend while next Gen stealth was being developed. Why spend the money on the "old" F117 when you are fielding F35s that are far more capable and have 1/3 the RCS?
The F117 and its highly accurate weapons scared the bejeezuz out of more then the Iraqis in Gulf 1. This airplane entered some of the most heavily defended air space in the world and took out whatever targets it wanted, and did so without a Loss. The Russian and Chinese watched in Horror and had to direct, and redirect, vast amounts of their wealth both to try and counter the threat it presented and to try and produce their own. That is the Legacy of the F117. A simple bomb dropper that changed warfare forever.
Yup :aok The Nighthawk was a game changer, even with its modest performance.
(http://www.fiddlersgreen.net/aircraft/Lockheed-F117/IMAGES/Lockheed-F117-Nighthawk-Stealth-Fighter-Bombing.jpg)
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The F117 shrunk the detection range of the mostly Soviet and French made defense radars in Iraq to the point where it was no longer an "integrated" defense network. The circles of detection range shrunk enough to make huge gaps in what was prior to the F117 being around, an overlapping defensive grid. I've heard some of the pilots say that the mission planning and route following system etc of the F117 was also a huge part of its success, being able to accurately penetrate through these gaps in radar and defense coverage.
Considering the sheer number of radars, and they high quality of these systems at the time, the F117 performed in a most stellar fashion in 1991, and continued to do so many years after that, only losing one, and another taking a close near miss in the Kosovo theater ops area. Just looking at the tiny fraction of aircraft sorties the F117 made up, and the huge numbers of high value targets that it took out, it's ridiculous to say anything against it. One loss compared to how many hundreds, no make that thousands of targets eliminated?
As others have pointed out, it was only retired due to the F22 and F35 being several orders of magnitude (apparently) less observable, in addition to also being true "fighters", something the F117 was not. The cost of maintaining a platform that was now easily outclassed by newer aircraft is pointless in these times of $ crunch.
Barret Tillman wrote an interesting book called "Warriors" back in 1991 or so. He was a fighter pilot, from the F8 Crusader community, one of the last "gunfighters", and being from that community, he was of the opinion that radar, ecm, all that stuff ranked far down the ladder in air to air combat next to a fighters performance so far as thrust/weight ratio, acceleration, turn rate/radius, visibility (size/eyeball, not RCS), simplicity (sorties per day possibly generated), and a good cannon and heat seeking armament. He wrote that radar missiles, even the fancy ones like the Amraam/Adder/AAM4/Etc, were mainly used to gain a better position or deny the enemy one, and that most of the killing even in the advanced age of stealth, radar, ecm, and fire and forget radar missiles, would always be done with heat seeking missiles and cannon. He felt that radar, ecm, stealth, all that electronic warfare related stuff would just end up cancelling each other out, and it would come down to eyeballs, seat of the pants, and heat seeker/cannon fights because of that. It's an interesting take, like I said, it was 20 years ago he wrote the book, but he's spoken about this issue many times, and even today still feels it is somewhat a valid opinion. Google some of it if anyone is interested, or check out the book, he builds an entire Air Force for a rich Arab state out of F20 Tigersharks, and most of them don't even have radar installed due to his beliefs and policy, which he weaves into the novel. I don't necessarily subscribe to all his idea, but as I said, they are interesting, and based on his experience, I can see why he thinks that way - Fighter Mafia on steroids more or less.
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Barret Tillman wrote an interesting book called "Warriors" back in 1991 or so.
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He wrote that radar missiles, even the fancy ones like the Amraam/Adder/AAM4/Etc, were mainly used to gain a better position or deny the enemy one, and that most of the killing even in the advanced age of stealth, radar, ecm, and fire and forget radar missiles, would always be done with heat seeking missiles and cannon. He felt that radar, ecm, stealth, all that electronic warfare related stuff would just end up cancelling each other out, and it would come down to eyeballs, seat of the pants, and heat seeker/cannon fights because of that.
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he builds an entire Air Force for a rich Arab state out of F20 Tigersharks, and most of them don't even have radar installed due to his beliefs and policy, which he weaves into the novel.
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People imagine an air battle as two formations heading towards each other starting at 100 miles separation. This is not how real intense air war looks like - usually. The IAF still subscribes to the close, visual range fighting and indeed considers the BVR weapons as an "advantage" rather then the main weapons. The main reason is that the Israeli fronts are very short and the fighting is expected to get very intense. The Syrian border in the Golan Heights is only about 30 miles long and during day operations over 100 IAF aircraft are expected to operate there. Add to that the opponents planes and you get an air war an order of magnitude denser than the Iraqi desert. There will be so much radars, ECM and other tramsissions in that space that birds will probably get fried in the air.
In such an environment a fighter pilot that turns on his radar will see tens or aircraft, that is if he can see anything at all with all the interferences in the air. The rocks in the Golan Heights are notorious for giving a lot of radar echos which degrade radar performance even more, especially in low elevations. This makes BVR very difficult, especially if you do not want to shoot your friends. Engagements are likely to start already withing 20 miles and close into the 10 miles range very fast where optical weapons start to factor in.
Not every war will be as ideal as the Iraqi campaign. Learning the lessons of the past and preparing to win yesterdays war is a classic error.
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Active detection systems like radar will be obsolete in the not too distant future. Manned combat aircraft too for that matter. Radiating energy that reveals your position is no longer really viable in today's EW environment. It has been likened to searching for an enemy soldier at night using a flashlight. Passive detection systems will become increasingly important, and the new "stealth" will be masking your emissions as much as possible.
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"It has been likened to searching for an enemy soldier at night using a flashlight."
Indeed. And add to that that the reflected energy needs to be high enough to be registered by your radar so if you can detect a target from 40 miles out your radiation is still detectable at range of 100 miles or more.
So in reality you radiation pattern is detectable from much higher ranges than you can detect even a big target, let alone a jet coming towards you with very small radar cross section.
Turning on you radar is like telling "Hey, here I am. Is there anybody there!?" and all the planes outside your range but inside your radiation cone will see you in their radar detectors before you even have a chance of knowing where they are.
Thus it is easy to understand why AWACS and ground radar systems with data links are so valuable and, of course, valuable targets as well.
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Radiating energy that reveals your position is no longer really viable in today's EW environment. It has been likened to searching for an enemy soldier at night using a flashlight. Passive detection systems will become increasingly important, and the new "stealth" will be masking your emissions as much as possible.
Indeed. And add to that that the reflected energy needs to be high enough to be registered by your radar so if you can detect a target from 40 miles out your radiation is still detectable at range of 100 miles or more.
So in reality you radiation pattern is detectable from much higher ranges than you can detect even a big target, let alone a jet coming towards you with very small radar cross section.
Turning on you radar is like telling "Hey, here I am. Is there anybody there!?" and all the planes outside your range but inside your radiation cone will see you in their radar detectors before you even have a chance of knowing where they are.
Not really, this is not how it works.
Emissions from your plane announce your presence, but measuring your exact location and speed for the purpose of guided armament is not easy. Normally it takes triangulation from several displaced receivers to do it and it is still not very fast or accurate. Self defense ECM is reactive in most modes, and will not transmit unless it detects a transmission it was designed to act against. The best that the enemy can know is your rough direction and very rough estimate of range if he knows your system well enough. Since it is not likely that the enemy knows your ECM system very well, detecting its emission and identifying it will not be possible by other fighters - ground stations will do that. The purpose of self ECM is not to hide your presence, it is to prevent accurate tracking by weapon systems and radars.
If you want to hide your presence, the plane has to fly in complete electronic silence. This means no radio, no radar, no active ECM, no data-links. In normal planes this also requires flying at very low altitudes on a path that has be studied in advance and that breaks the line of sight from the main enemy search radars. Radars are more dense along the front, so such mission are also supported by ECM from other elements that degrade the detection performance of the defenders. A stealth plane may fly a more relaxed profile (they are also not perfectly stealthy from all directions), but it is as much blind and muted as any other plane in electronic silence.
Stealth helps, but is often not critical, and in many missions completely unrequited. Do you need a handful of expensive planes to do all these missions, or are you better served by a larger force of conventional planes? Stealth makes a real difference only on a small number of certain missions. These few missions are important, but replacing your entire airforce with stealth planes seems unwise.
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Upcoming sats generation is designed to spot wannabe stealth aircrafts/boats : untill they manage to make aircrafts fly in a different dimension untill they fire, no object will be 100% stealth IRL it seems....
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I wonder how good the new AESA radars are, like the set in the F22? I've often read that they only need to radiate for quick busts of time, like miliseconds, and then rapidly switch off, so quick that many RWR don't even detect them, not to mention they hop frequencies often, and further confuse warning receiving equipment.
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More importantly Gman, each element on these phased arrays operate independently at random frequencies so their total output is difficult to tell apart from background noise. To third-world equipment they are all but undetectable and practically impossible to jam.
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More importantly Gman, each element on these phased arrays operate independently at random frequencies so their total output is difficult to tell apart from background noise.
First of all it isn't correct...
The radar still needs to form a beam - which is done by multiple sources working on the same frequencies on different phases - it is the plane physics (see interference).
However if you spread the signal across the frequencies you still get the accuracy and the resolution reduced - because the more sources you have the sharper the main lobe and the other way around.
The major advantage of AESA is that you can much easily change the frequencies and operate different parts of the radar on different frequencies - forming multiple beams at once (tracking different targets). This helps against the detectors that search for multiple peaks on the same frequencies - the typical RWR.
But yet you need to generate a strong signal that its power reduced is 1/d^2 for RWR while the radar itself receives the signal with 1/d^4 where is d is the distance between the radar and the target - so RWR always has an edge over the radar.
Bottom line AESA is LPI for older RWR - they also would be harder to spoof because it can change direction & frequency for each pulse...
But saying that "each element operates independently at random frequencies" is just incorrect.
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You got something mixed there Boz.
"Emissions from your plane announce your presence, but measuring your exact location and speed for the purpose of guided armament is not easy. Normally it takes triangulation from several displaced receivers to do it and it is still not very fast or accurate."
You emitting radar radiation is no different from a system that lights you with radiation (except that your emission has more power) and a missile homing on you e.g. beam-rider missiles. Also SHRIKE and HARM were meant to do just that, home on radar emission. I guess the new AARGM is still more powerful in homing. The problem with employing this kind of missiles is always the same: what if the enemy shuts down his radar? Homing on a ground based cold radar is easy using INS/GPS if you get the initial reading but in the air it is impossible, but the fact remains, if you have your radar on you can be tracked and the accuracy depends on the antenna system on the receiving end.
"If you want to hide your presence, the plane has to fly in complete electronic silence. This means no radio, no radar, no active ECM, no data-links."
You could also rank them while your at it.
1. Radar (Hey here I am!) :x (Power is in kilowatts)
2. ECM (Hey, I'm somewhere in this direction!) :huh (Power is in kilowatts)
3. Datalink (https://www.rockwellcollins.com/sitecore/content/Data/Products/Communications_and_Networks/Data_Links/Joint_Tactical_Information_Distribution_System.aspx) (MIDS has the same power rating, 200W)
4. Radio (Hey, Im around!) :headscratch: (Power is probably a couple of hundred watts)
Datalink and radio are probably not much different except that with radio you can choose when to reply (and emit power). Datalink is mainly on one direction but I suppose the system sends some data back to announce it has received data. Thus the radiation is not entirely dependent of the pilot in the fighter. But the operating mode of radio and datalink makes them very hard to track. If you know the frequencies you can tell that something is going on but where and what is more difficult to figure out.
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You got something mixed there Boz.
"Emissions from your plane announce your presence, but measuring your exact location and speed for the purpose of guided armament is not easy. Normally it takes triangulation from several displaced receivers to do it and it is still not very fast or accurate."
You emitting radar radiation is no different from a system that lights you with radiation (except that your emission has more power) and a missile homing on you e.g. beam-rider missiles. Also SHRIKE and HARM were meant to do just that, home on radar emission. I guess the new AARGM is still more powerful in homing. The problem with employing this kind of missiles is always the same: what if the enemy shuts down his radar? Homing on a ground based cold radar is easy using INS/GPS if you get the initial reading but in the air it is impossible, but the fact remains, if you have your radar on you can be tracked and the accuracy depends on the antenna system on the receiving end.
I was refering to all emissions in general. However, even the radar does not give your location with sufficient accuracy to guide weapons to you. Anti radar missiles such as HARM have a low angular resolution - they just get close enough to the target till the low resolution is sufficient... They also repeatedly measure and correct the calculated location of the target as they fly, thus require a certain flight path to acquire the target with sufficient accuracy to follow and get close enough. Also, remember that ground radars are always at altitude zero AGL. If you know the direction in 3D space and know where the ground is, you know the range. No so in the air.
This will not do to intercept a flying target. To track your position as if you are tracked by a radar they need multiple antennas that read the direction to you and then triangulate. This is quite clumsy and used as intel but not to actively track you. The radar on the plane can jump frequencies and is not so easy to get a good triangulation on with a high update rate. So yes, they know you are there, they know roughly where you are, but then they still have to acquire you by other means attached to a weapon system in order to do anything about it.
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First of all it isn't correct...
The radar still needs to form a beam - which is done by multiple sources working on the same frequencies on different phases - it is the plane physics (see interference).
That's the older PESA radars with the single microwave source and a series of delays to drive the array. In the AESA, each element is driven at a different frequency, even within a single pulse, so there is no high-power signal at any given frequency. The radar unit knows which frequencies were broadcast, and amplifies and combines only those return signals, thereby reconstructing a single powerful echo on reception. The target is unaware of which frequencies are active and has no strong signal making detection on radar warning receivers very difficult.
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I stumbled upon a seeker type 9B-1032 which suggests that Russia may have a passive radar homing A to A seeker.
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That's the older PESA radars with the single microwave source and a series of delays to drive the array. In the AESA, each element is driven at a different frequency, even within a single pulse, so there is no high-power signal at any given frequency.
It has nothing to do with PESA it has to do with physics and waves.
For example lets have to coherent sources of radio waves of the wavelength 5 cm.
If I turn only one of them than the signal would be distributed equally at 360 degrees. Now I put 2 such sources at the distance of 2.5cm radiating coherently. Now at the direction perpendicular to these two sources the waves would combine and you have a signal twice its strength and in a direction parallel to these sources the signal of one source would be nullified by another because they would be at inverse phase (due to 1/2 wave length distance)
So basically in front of them you get signal twice stronger and at 90% on sides of this simple antenna you get none of the signal and at 45 degrees you have something between them.
More sources you combine the more significant effect becomes - i.e. you create a narrower beam - that goes in specific direction such that you can have a resolution of few degrees and use it to detect the targets.
If each element operates on its own different frequency - you can't create a beam - the different frequencies do not interfere - basically instead of creating a strong concentrated flashlight that radiates in specific direction you get a lamp that illuminates at 360 degrees.
It is just a basic physics of wave propagation.
AESA is not that much different from PESA - the difference is that you can create several directed beams using different frequencies using the same radar instead of using single transmitter and adding delays in the signal...
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I don't make the darn things, I just listen to the people who do. Most of what they say goes over my head, but as far as I've understood it they use advanced digital beamforming to produce agile synthetic wideband waveforms (and ultra low sidelobes). I.e. a waveform that combines many different frequencies that through harmony or disharmony forms the beam. This allows each element or small groups of elements to operate at different frequencies thus spreading the transmitted energy across a wide band of frequencies. Add pseudo-random noise algorithms to the chirp and you get something that is just noise to any RWR that doesn't know exactly what to look for. At least that's how I understand it.
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Seems like the Dehaviland mosquito was an early stealth fighter/bomber being made out wood. It's cover has always been that Britain was running out of strategic metals for building planes and therefore had to use wood, however it had a smaller radar signature for its size. It was one of the few planes that could be sent into enemy territory by itself.
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Seems like the Dehaviland mosquito was an early stealth fighter/bomber being made out wood. It's cover has always been that Britain was running out of strategic metals for building planes and therefore had to use wood, however it had a smaller radar signature for its size. It was one of the few planes that could be sent into enemy territory by itself.
That is a myth. The mossie shows just fine on radar. "All wood" refers to the fuselage and wings. The engines, cables, landing gears, electronics, and like a million nails had plenty of metal in them.
Birds show on radar btw, even those without lead pellets in their body.
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That is a myth. The mossie shows just fine on radar. "All wood" refers to the fuselage and wings. The engines, cables, landing gears, electronics, and like a million nails had plenty of metal in them.
Birds show on radar btw, even those without lead pellets in their body.
Not to mention the props. Huge radar reflectors.
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That is a myth. The mossie shows just fine on radar. "All wood" refers to the fuselage and wings. The engines, cables, landing gears, electronics, and like a million nails had plenty of metal in them.
Birds show on radar btw, even those without lead pellets in their body.
The first German radars had a wavelength measured in meters so even the engines of the moss where too small to reflect the radar signal and it was therefore invicible on radar. However the german switched to smaller wavelengths that could detect the Moss pretty soon.
But there are other examples of ww2 stealth aircrafts: http://en.wikipedia.org/wiki/Horten_Ho_229#Stealth_technology
"RCS testing showed that a hypothetical Ho 229 approaching the English coast from France flying at 885 kilometres per hour (550 mph) at 15–30 metres (49–98 ft) above the water would have been visible at a distance of 80% that of a Bf 109. This implies a frontal RCS of only 40% that of a Bf 109 at the Chain Home frequencies. The most visible parts of the aircraft were the jet inlets and the cockpit, but caused no return through smaller dimensions than the CH wavelength. Given the high-speed capabilities of the aircraft it would have given the British defences just two and a half minutes to respond, which would not have been enough time. It is believed that, if deployed in quantity, the Ho 229 could have changed the course of the war"
Btw almost all modern fighters (in the west atleast) has a lot of stealth features, like the design of the air intake etc. Planes like Gripen, EF and Rafale are not as extreme as the F-22 but their rcs is much smaller than the rcs of their predecessors.