is it possible to track a 5th gen fighter..

[Kaktus29]

by sound? ..in this situation the plane is invading your airspace..and if you put lots of sound detectors across the nation and since sonic boom is heard (maybe not by human ear when plane is at 60.000 feet, but by device sensitive enough yes,most likely..) .. and triangulate the origin to give you approximation of the location of fighter?

 

i know this is how they used to locate incoming bombers in 2WW in the very beggining but found radar to be faster, more accurate also practical since you get to intercept the bombers where any sound detection is only good when the plane is actually above you and crossing across the devices network ..

 

but with today's modern devices could this be a potential one more element to be careful in designing the 5gen fighter..one that cannot be resolved because it goes against the other 5gen requirement -supercruise-meaning most of the time the jet will go supersonic thus detectable by sound network?..

 

just putting it out there..don't kill me, just give me good rebuttal why this wouldn't work and why it could..

 

one problem i see is its mostly defensive (in the case it works) ..this network is land based in your country so you can't use it for invading into enemy airspace..

second problem is, it could be potentially jammed by all kind of sound jammers altough it would be very technologically difficult to implement this jammer all across the targeted nation..

 

why it would work? Triangulation is proven, and works, even the sound one not just the radio one..

it would be cheaper than radar, all you need is small devices to detect sound and put it in sound -neutral places .. like in the middle of the field etc.. but with processer power it could filther out the local residual sound so it wouldn't be too much problem focusing on the low thump of the sonic boom happening somewhere 60.000 feet above.. then all this info goes to C&C where it is combined with thousands of other sound devices to create a firing solution and boom if it works there is one hell of a passive way to bring 5gen down cheaply and swiftly..

also it would be 100 % passive system that would feed firing solutions to all kind of systems-from AD systems to CAP's .. it would make 3gens fighters useful as a air firing platform ..

Edited February 26, 2013 by Kaktus29

[Eddie]

Totally pointless, but yeah, in theory it could work. In practice however, no.

 

But why would you bother when existing systems such as IRST and RADAR (yes RADAR) would be far more effective.

[Kaktus29]

radar? because its not passive.. you would alert your position to the enemy.. you do understand the difference in active and passive systems.. IRST is good but again you will not detect F-22 unless you are close..also the pollution of air is at high concentration at the ground meaning IRST ground based is wasteful as it wouldn't be best effective..but if you put it on the plane you are putting the plane crew in danger..

 

you say it would not work in practice? why? .. i would like some more elaborate arguments than just saying.. naaah, it wouldn't work.. why?..

 

This system is for detecting 5gens screaming across the skies and putting them down.. IRST cannot come close to this.. unless you make IRST drone that is very cheap, also flies very high, and is very stealthy.. meaning you get yourself a much more expensive proposition for my sound stuff theory..

 

i know what i propose is hard, i just don't know why.. it has to be with either the math behind the algorithms in detecting and understanding the triangulation..is it that? or is it the case it would be expensive? ..i mean, it has to be a stupid idea since nobody has tried it before and i can't be the genius who thought of this first..so, i just want to find the plot holes in this.. and if you could be please so kind to help me out and not just say -naaaah, its pointless.. ))

[Sov13t]

Sound is just as inaccurate as IR signatures, if not more, it is just as vulnerable to weather conditions/temperatures and will not provide a worthwhile target resolution/accuracy. Now if we were under water... ;)

 

"There is something loud out there"... that's about as far as you will get. In WW2 that was enough, today... not really.

 

Given that airspace is saturated with all types of radar emissions, a fifth generation fighter intruding enemy air space will already be receiving all types of nails... and he won't really know if he has been detected or not.

[sobek]

"There is something loud out there"... that's about as far as you will get. In WW2 that was enough, today... not really.

 

That's not true. If you had a large enough microfone array, you could track the source rather accurately, but then there's always the delay, attenuation and susceptibility to noise.

[Sov13t]

That's not true. If you had a large enough microfone array, you could track the source rather accurately, but then there's always the delay, attenuation and susceptibility to noise.

 

So how is it not true? "There is something loud out there"...

 

It would not be enough to provide tracking guidance for any sort of reasonable weapon, and the saturation of these arrays would have to be rather high in order to attempt accurate triangulation of the source.

 

Not to mention constant tracking of atmospheric conditions over a rather large area of space for accurate calculations. And even if all conditions were perfect, as you mentioned, the speed of sound is just not there for the word "accurate" to be used, unless of course "accurate" for you means "There is something out there".

[marcos]

radar? because its not passive.. you would alert your position to the enemy.. you do understand the difference in active and passive systems.. IRST is good but again you will not detect F-22 unless you are close..also the pollution of air is at high concentration at the ground meaning IRST ground based is wasteful as it wouldn't be best effective..but if you put it on the plane you are putting the plane crew in danger..

 

you say it would not work in practice? why? .. i would like some more elaborate arguments than just saying.. naaah, it wouldn't work.. why?..

 

This system is for detecting 5gens screaming across the skies and putting them down.. IRST cannot come close to this.. unless you make IRST drone that is very cheap, also flies very high, and is very stealthy.. meaning you get yourself a much more expensive proposition for my sound stuff theory..

 

i know what i propose is hard, i just don't know why.. it has to be with either the math behind the algorithms in detecting and understanding the triangulation..is it that? or is it the case it would be expensive? ..i mean, it has to be a stupid idea since nobody has tried it before and i can't be the genius who thought of this first..so, i just want to find the plot holes in this.. and if you could be please so kind to help me out and not just say -naaaah, its pointless.. ))

Radar can now be passive and in countries perforated with EM radiation of all kinds they can be very effective.

 

IRST and other optical systems are also showing very huge increases in performance. A ground-based IR system that's actually going to get a chance to look at the hot end of the aircraft without being killed could also be very useful.

 

Your sound theory has merit and it's actually based on an old method to an extent (used at the start of WWII). Not sure if it could detect subsonic stuff very well though.

 

ESM also has merits.

 

The best bet is probably a combination of all the above with data fusion algorithms to weed out noise and focus on areas of interest. If you can pick out a suspicious area and switch to very narrow beam, even a radar will work quite well.

[Kaktus29]

@sobek..yeah i read about those dishes in Britain during the 2WW..and yes, they could get quite good info of the enemy, even range.. the problem was it was all delayed... thats why its useless to use this as interceptor system-as in intercepting incoming planes that have yet to breach your airspace..where i propose a different system where you do exactly that.. planes flying in your airspace well within the network of thousands of listening arrays doing their million per second match crunching equation and detecting the position of planes..

 

i'm not saying its not complicated, this is science of sound..so far no serious science or investment has gone into it..it has when it comes to underwater sonar systems.. but not so much for the air..

 

i just liked the idea because all this 5gens will be breaking the sound barrier ALL the freakin time)) it is such a waste of not doing something with that info like that..

[Kaktus29]

@marcos.. yes, your right.. i have read allot about chech scientis who developed during USSR and after it fell many passive systems to detect VLO's..

 

and IRST i always though would be great addition to ground stations spread into a network across the nation but always though that there is diminished result because its on the ground where air is more filthy and heavy with pollution particles..

 

i've read russia is proposing a new ground based detection system that will be based on allot of what you wrote.. to be totally passive and use many different ways and channels detecting stuff..

 

i wonder if the sound will be one of them..

 

i know sound is lagging.. like in breaking the speed barrier.. but that could be calculated in the equation.. so you know its lagging, you know that means the plane is position minus the lagging factor equals the real position.. and than fire a missile with infra-optical combined seeker warhead in general area..maybe fire even 2,3 to cover more space.it depends on how closely can you isolate the contact..if this is less than 2-5 km2 1 missile can cover this with advanced optic-IR seeker heads.. this things have the eyes of an eagle..can spot a bird 10 km away,this was from an israeli optical seeker head..don't remember the missile. was it paytheon or smth?..

[Sov13t]

i know sound is lagging.. like in breaking the speed barrier.. but that could be calculated in the equation.. so you know its lagging, you know that means the plane is position minus the lagging factor equals the real position...

 

So, you do not have accurate up to speed measure of the aircraft even if it is subsonic due to latency of sound, atmospheric distortion and noise. Now you are introducing supersonic speeds, which could be Mach 1... or could be Mach 2.5. And you have absolutely NO way of knowing what it is unless you start spreading your arrays over a significant distance and start analyzing frequency shift etc. Not to mention you have to have sound profiles of your probable targets to try and have something to cross reference. By now, even if you are able to get this far, the target had to cover a significant portion of your detection envelope and you have a tracking with a margin of error ~.25 so yes, let's lob 20 missiles at an area in the sky and hope they acquire something... or better yet a tactical nuke. Sonar works because the medium is denser where the sound travels much faster up to a factor of 4, the targets much larger and speeds are slower.

 

This reminds me of the U-2 shoot down over Russia, where PVO did a SPAMRAM into the general vicinity of the target without having a very accurate lock due to ranges/altitudes involved. It was a bad idea.

 

A good read on sound in general for your basic understanding: Calculating Distance based on Sound

Edited February 26, 2013 by Sov13t

[Maior]

Not to mention the most basic point, if the aircraft is supersonic, he'll reach you first than the sound it produces. Plain and simple. If an aircraft is travelling at Mach 2, the sound will only reach the sensor after the aircraft has passed it. Not much of a purpose now is there? If you consider that the speed of sound is 333 m/s (approximate, let's not consider that the speed varies with altitude and that the sound wave is refracted as it propagates through mediums of different densities), a Mach 2 AC is doing 666 m/s

so, if the sensor has a 100 Km radius (pretty huge for sound based sensors) and supposing that the wind is right, not blowing in the other direction, the sound waves would take 300 seconds to reach the sensor. In 300 seconds, the AC would be 200 Km away... So basically, If you detected the sound off the coast of Dover (using WWII) the aircraft would have bomber London and be over Dover again once they were detected (Dover-London distance is about 105Km)... Not much use in that...

[GGTharos]

by sound? ..in this situation the plane is invading your airspace..and if you put lots of sound detectors across the nation and since sonic boom is heard (maybe not by human ear when plane is at 60.000 feet, but by device sensitive enough yes,most likely..) .. and triangulate the origin to give you approximation of the location of fighter?

 

I don't see why not, this is being suggested as an early warning system by many.

 

I don't know about triangulation, I mean, I wouldn't expect to get weapons guidance grade accuracy. I can see detecting the intruder, but not necessarily tracking very well.

 

but with today's modern devices could this be a potential one more element to be careful in designing the 5gen fighter..one that cannot be resolved because it goes against the other 5gen requirement -supercruise-meaning most of the time the jet will go supersonic thus detectable by sound network?..

 

Are you trying to detect a fighter, or a bomber? Detecting a fighter might not be all that useful, but who knows.

 

then all this info goes to C&C where it is combined with thousands of other sound devices to create a firing solution and boom if it works there is one hell of a passive way to bring 5gen down cheaply and swiftly..

 

You're not going to get a firing solution out of this. Your sensor is slower than your target. That's a problem. And while a microphone might not be terribly expensive on its own, getting a firing solution grade track would require insanely vast arrays of such equipment. And even so you are tracking where the aircraft WAS and not where it IS, so your firing solution predictions can be trashed with just a few degrees worth of gentle maneuvering by that aircraft.

 

What you could do is alert the IADS where you detected the intruder, and then try to cue in more accurate sensors.

[GGTharos]

Ok, think about this, and assume that your sound detectors are perfect for a moment (they are not, your triangulation may have significant error).

 

Assume you have a plane going M0.95 at 60000', or even M1.

 

Sound travels at about 1000fps (the speed changes depending on altitude/density/yadda, but we will ignore this for the sake of the argument) so it takes 60sec for the sound to reach your detectors.

 

At that speed, this aircraft will have flown 15-20km. More if it's going faster (it won't be going slower at 60000').

 

So your detection is 60 sec/15km late, and your track has an automatic 15km error.

 

You could assume that the plane will fly straight, but all he has to do is fly a bit of a left-right and cause you to have multiple kilometers in targeting error, causing you to shoot missiles uselessly into the sky.

 

Now if you cue some infra-red search system or even a radar search system that happens to be close enough to pick this guy up, things change.

 

But the problem is that to make this really effective, you once more need a very dense sensor network, which is prohibitively expensive.

 

i know sound is lagging.. like in breaking the speed barrier.. but that could be calculated in the equation.. so you know its lagging, you know that means the plane is position minus the lagging factor equals the real position.. and than fire a missile with infra-optical combined seeker warhead in general area..maybe fire even 2,3 to cover more space.it depends on how closely can you isolate the contact..if this is less than 2-5 km2 1 missile can cover this with advanced optic-IR seeker heads.. this things have the eyes of an eagle..can spot a bird 10 km away,this was from an israeli optical seeker head..don't remember the missile. was it paytheon or smth?..

[marcos]

The lag is definitely a problem but the frequency shift of the sound and the time at which it arrives at different sensors could be used to triangulate it and map a path that the aircraft has taken and its speed and predict where it might be now, then use other sensors in the predicted location. It could be useful to map attack corridors being used by the enemy if nothing else.

 

It's probably not useful as a standalone system but as an input to a more advanced system, it's useful. If its sensitive enough, it may also be able to detect the sound being transmitted via the ground, i.e. shock wave hits the ground 5 miles below aircraft then travels at 8-10km/s through the earth.

 

I prefer the idea of passive radar though. If you have all sorts of mobile devices and satellite comms bouncing EM around the atmosphere and you know where they've come from, you can detect disturbances in their travel. It's like having lots of high power, multi-frequency radars dotted around everywhere.

[Maior]

The lag is definitely a problem but the frequency shift of the sound and the time at which it arrives at different sensors could be used to triangulate it and map a path that the aircraft has taken and its speed and predict where it might be now, then use other sensors in the predicted location. It could be useful to map attack corridors being used by the enemy if nothing else.

 

It's probably not useful as a standalone system but as an input to a more advanced system, it's useful. If its sensitive enough, it may also be able to detect the sound being transmitted via the ground, i.e. shock wave hits the ground 5 miles below aircraft then travels at 8-10km/s through the earth.

 

I prefer the idea of passive radar though. If you have all sorts of mobile devices and satellite comms bouncing EM around the atmosphere and you know where they've come from, you can detect disturbances in their travel. It's like having lots of high power, multi-frequency radars dotted around everywhere.

 

 

You can probably narrow down the search area but as the receivers get further away, the longer you will have to wait for the combined data. For example, if three sensors detected a sound, one at 15 the other at 20 and the other at 50Km away, in order to get a triangulation you'd need to wait for the sound to reach the 50 Km one. That means you'd have to wait around 150 secs to have all the data. That's 3min 50 secs. By which time the aircraft would be far away. Not to mention that if you have an opposing wind sound would be even more muffled. The only practical idea would be to develop some kind of laser microphone who could detect movement of air particles but again, if lasers are in question, a LIDAR system painting the sky would be your best bet. That way, you could pretty much pinpoint the aircraft if he's visible to the naked eye. You just couple that with the LIDAR

Reference frame and you'd get the exact position of the aircraft and it's speed due to Doppler shift. Plus, they can shift their frequencies and if you have several overlapping systems you'll get a pretty accurate picture. At 1Km height, public domain LIDAR systems can have centimetre resolution. If you have more lasers in it, you can even increase resolution and get 360º coverage constantly.

 

Also, there is no system at present that can detect and provide direction to directional EM systems coming from space. And VLO platforms are design to be EM silent. This is especially true now that AESA RADARS can be used to send and receive communications being able to replace datalink which is much "louder" by comparison.

[Jona33]

That means you'd have to wait around 150 secs to have all the data. That's 3min 50 secs. By which time the aircraft would be far away.

 

150 secs equals 2 minutes 30 secs? All right I'll stop being irritating. :P:P

[GGTharos]

More importantly it also equals around 25nm. :P

 

150 secs equals 2 minutes 30 secs? All right I'll stop being irritating. :P:P

[Sorin]

Thunder is really loud and it will mess badly the detection by sound...

Same for various explosions, if we talk a war scenario.

[Maior]

150 secs equals 2 minutes 30 secs? All right I'll stop being irritating. :P:P

 

 

Lol. Nice catch. 2 minutes thirty not three minutes thirty. :p