Discussing stealth

[Yellonet]

I would like to start a discussion about stealth, how it works, and how it could possibly be counteracted.

 

From what I've understood about (radar) stealth it is basically done by deflecting as much of the incoming energy away from the aircraft in a direction where the emitting aircraft can't revieve it. Also some of the energy is absorbed by using special materials.

 

When the enery off of a stealth plane is deflected, is it done so in a mirrorish way with the incoming "beam" intact or is the incoming energy scattered all around dividing the energy over a large area?

 

I wonder if it would be possible to have a network of radar recievers on the ground or possibly even a satelite network that could detect the deflected energy off of otherwise "invisible" objects to work in conjuction with either airborne or ground based radar emitters.

I guess this theory hangs on how much of the energy is deflected and how it is spread out. Do you think it is possible?

 

Gentlemen, theorize ;)

[monotwix]

I would like to start a discussion about stealth, how it works, and how it could possibly be counteracted.

 

From what I've understood about (radar) stealth it is basically done by deflecting as much of the incoming energy away from the aircraft in a direction where the emitting aircraft can't revieve it. Also some of the energy is absorbed by using special materials.

 

When the enery off of a stealth plane is deflected, is it done so in a mirrorish way with the incoming "beam" intact or is the incoming energy scattered all around dividing the energy over a large area?

 

I wonder if it would be possible to have a network of radar recievers on the ground or possibly even a satelite network that could detect the deflected energy off of otherwise "invisible" objects to work in conjuction with either airborne or ground based radar emitters.

I guess this theory hangs on how much of the energy is deflected and how it is spread out. Do you think it is possible?

 

Gentlemen, theorize ;)

 

As much as I'm trying to grasp the meaning of this post, I think that it has to do more with physics and science than military planes and those people who know and deal with it best.

The energy deflection and it's spreading with what and how it worked with F-117, doesn't realy mean that thay are not detectible, it's more like once detected and it's hard to pinpoint it's location and this may not apply to other stelath planes as we know the name and subject of stealth technology.

[britgliderpilot]

I would like to start a discussion about stealth, how it works, and how it could possibly be counteracted.

 

From what I've understood about (radar) stealth it is basically done by deflecting as much of the incoming energy away from the aircraft in a direction where the emitting aircraft can't revieve it. Also some of the energy is absorbed by using special materials.

 

When the enery off of a stealth plane is deflected, is it done so in a mirrorish way with the incoming "beam" intact or is the incoming energy scattered all around dividing the energy over a large area?

 

I wonder if it would be possible to have a network of radar recievers on the ground or possibly even a satelite network that could detect the deflected energy off of otherwise "invisible" objects to work in conjuction with either airborne or ground based radar emitters.

I guess this theory hangs on how much of the energy is deflected and how it is spread out. Do you think it is possible?

 

Gentlemen, theorize ;)

 

The reflected energy is scattered in as many directions as possible - that is, the energy that IS reflected, rather than absorbed by RAM.

 

With a sufficiently sensitive and widespread receiver array and a central processing unit, it's absolutely possible to detect a stealth aircraft from this scattered energy ;)

If a load of tiny returns are all coming from the same spot in the sky, it rapidly becomes just an issue of software and processing.

 

It's been theoretically possible for a while, and while to the best of my knowledge nobody has yet done it, for a country with sufficient know-how and funding it wouldn't be THAT much of a challenge . . . .

 

Thing is, nobody's yet felt the need. Shrug.

 

 

- Monotwix:

 

The point of the F-117 wasn't that it's difficult to pinpoint; rather it was that by the point where it was detected there was no longer sufficient time to get it locked up and to fire :)

 

From detecting an aircraft, to locating it, locking it up, and firing a guiding a missile inevitably takes time - particularly in the Soviet system.

 

The F-117 would, in all probability, have been detected by Soviet radar at close range - but the key point to understand is that it would NOT have been detected by Soviet radar in time to prevent it dropping it's weapons (i.e. if it was detected, lock and launch could not have been achieved before bombs away). And that's what mattered.

 

 

Against a sophisticated system, the same still stands - but very few truly sophisticated SAM networks still exist.

 

Modern stealth in the air-to-air role follows the same principle; you're not invisible, but you won't be detected until long after you've fired . . . by which time your shot may already have struck home.

[monotwix]

The reflected energy is scattered in as many directions as possible - that is, the energy that IS reflected, rather than absorbed by RAM.

 

With a sufficiently sensitive and widespread receiver array and a central processing unit, it's absolutely possible to detect a stealth aircraft from this scattered energy ;)

If a load of tiny returns are all coming from the same spot in the sky, it rapidly becomes just an issue of software and processing.

 

It's been theoretically possible for a while, and while to the best of my knowledge nobody has yet done it, for a country with sufficient know-how and funding it wouldn't be THAT much of a challenge . . . .

 

Thing is, nobody's yet felt the need. Shrug.

 

 

- Monotwix:

 

The point of the F-117 wasn't that it's difficult to pinpoint; rather it was that by the point where it was detected there was no longer sufficient time to get it locked up and to fire :)

 

From detecting an aircraft, to locating it, locking it up, and firing a guiding a missile inevitably takes time - particularly in the Soviet system.

 

The F-117 would, in all probability, have been detected by Soviet radar at close range - but the key point to understand is that it would NOT have been detected by Soviet radar in time to prevent it dropping it's weapons (i.e. if it was detected, lock and launch could not have been achieved before bombs away). And that's what mattered.

 

 

Against a sophisticated system, the same still stands - but very few truly sophisticated SAM networks still exist.

 

Modern stealth in the air-to-air role follows the same principle; you're not invisible, but you won't be detected until long after you've fired . . . by which time your shot may already have struck home.

 

Yes sort of makes sense absolutely.

And all that of course.

[monotwix]

I don't wana be rude but I've seen the bombing on tv and I think harriers and B-52s did their job nicely but precision bobmbing with whatever no.no. no (to many misses).

[rogue_blade]

i dunno these days all your is Harry Potter's invisibility cloak which is impervious to all detection spells

[monotwix]

i dunno these days all your is Harry Potter's invisibility cloak which is impervious to all detection spells

 

Well good for you guy good for you, don't do no more!

[RvEYoda]

It would be fun to use to frequency modulating stealth too, but I guess that would fall under ECM. Put some nice crystals on the edge of the plane :)

[D-Scythe]

The reflected energy is scattered in as many directions as possible - that is, the energy that IS reflected, rather than absorbed by RAM.

 

Both absorption and reflection happens - what energy is reflected would be of much weaker strength than if reflected off a non-RAM coated aircraft.

 

With a sufficiently sensitive and widespread receiver array and a central processing unit, it's absolutely possible to detect a stealth aircraft from this scattered energy ;)

If a load of tiny returns are all coming from the same spot in the sky, it rapidly becomes just an issue of software and processing.

 

It's not that simple - such a proposed receiver would be subjected to radar reflections from other aircraft, chaff, jammers/ECM, missiles, clouds, birds, atmospherics or even the ground/sea, all of which would produce MUCH more powerful radar returns than those bouncing off a RAM coated stealth aircraft.

 

Furthermore, even if you manage to filter out the clutter and pinpoint that very weak signal amidst the mess in things, you're still tracking your target passively, not actively. That denies a large fraction of what your software and processing units can do, compared to actively tracking a target. In fact, I'd be interested how you can even derive range information without the use of datalink/triangulation.

 

Finally, perhaps the worse thing is that you'd actually have to have a huge, powerful radar flood the skies with radar waves in order to bombard these radar stealth targets with RF energy. Such a radar will get pinpointed and made a priority for destruction from the moment the system turns its radar on - either from a HARM if it's ground based or an AIM-120 through it's tailpipe if its airborne.

 

It's been theoretically possible for a while, and while to the best of my knowledge nobody has yet done it, for a country with sufficient know-how and funding it wouldn't be THAT much of a challenge . . . .

 

Such a system may have worked against the F-117, which can only carry LGBs. Against an opponent armed with long-range missiles (like F-35 or B-2) or a kinematically challenging opponent (like the F-22), it would get destroyed within the opening seconds of any conflict.

 

Even against the F-117, there's nothing to stop it from simply flying around the radar receiver array on the ground, or friendly fighters saturating the system with TALD decoys and HARMs.

[Yellonet]

The reflected energy is scattered in as many directions as possible - that is, the energy that IS reflected, rather than absorbed by RAM.

 

With a sufficiently sensitive and widespread receiver array and a central processing unit, it's absolutely possible to detect a stealth aircraft from this scattered energy ;)

If a load of tiny returns are all coming from the same spot in the sky, it rapidly becomes just an issue of software and processing.

 

It's been theoretically possible for a while, and while to the best of my knowledge nobody has yet done it, for a country with sufficient know-how and funding it wouldn't be THAT much of a challenge . . . .

 

Thing is, nobody's yet felt the need. Shrug.

I thought it would be possible, nice to get it confirmed :)

 

I read somewhere that Russia was about/already had invest(ed) money in a new radar system for aerial defence. Personally I think they would be benefitted greatly by a system like what we discussed. Even more so as they are behind in the aircraft vs. aircraft department.

Also, if a system like this would be made it could very well be made mobile, thus being very suitable for export and or lending to countries in need.

[Yellonet]

Both absorption and reflection happens - what energy is reflected would be of much weaker strength than if reflected off a non-RAM coated aircraft.

 

 

 

It's not that simple - such a proposed receiver would be subjected to radar reflections from other aircraft, chaff, jammers/ECM, missiles, clouds, birds, atmospherics or even the ground/sea, all of which would produce MUCH more powerful radar returns than those bouncing off a RAM coated stealth aircraft.

 

Furthermore, even if you manage to filter out the clutter and pinpoint that very weak signal amidst the mess in things, you're still tracking your target passively, not actively. That denies a large fraction of what your software and processing units can do, compared to actively tracking a target. In fact, I'd be interested how you can even derive range information without the use of datalink/triangulation.

 

Finally, perhaps the worse thing is that you'd actually have to have a huge, powerful radar flood the skies with radar waves in order to bombard these radar stealth targets with RF energy. Such a radar will get pinpointed and made a priority for destruction from the moment the system turns its radar on - either from a HARM if it's ground based or an AIM-120 through it's tailpipe if its airborne.

 

 

 

Such a system may have worked against the F-117, which can only carry LGBs. Against an opponent armed with long-range missiles (like F-35 or B-2) or a kinematically challenging opponent (like the F-22), it would get destroyed within the opening seconds of any conflict.

 

Even against the F-117, there's nothing to stop it from simply flying around the radar receiver array on the ground, or friendly fighters saturating the system with TALD decoys and HARMs.

What I was thinking was that the system of passive radar recievers would have a datalink with aircraft and ground based radars, not a giant radar of it's own, thus making it invisible to the enemy.

 

The system would know where a radar, airborne or groundbased, was directing its beam and what information it got back, anything showing up on the screens of the radar emitting sources would obviously be filtered out, what would be left would therefore be reflections of objects "invisible" to the regular radar systems. Therefore the system is in effect active, even though it does not have a radar of its own.

 

The system would then give the data back to the beaming system, giving them an advantage as the stealth aircraft would never know that it is being tracked, it can tell that it is being subjected to radar energy, but the pilot would assume that he had not been detected as would be in normal circumstances.

If there were to be missiles connected to this datalink, the stealth aircraft would never know what hit it.

[Kula66]

The reflected energy is scattered in as many directions as possible - that is, the energy that IS reflected, rather than absorbed by RAM.

 

BGP, this doesn't sound right - stealth faceting (as used in 117) concentrates reflected energy in a very few directions, and the aim is to deny the transmitter a long look in that direction. So if you turn they get a flash of reflected energy as the a/c presents that face ... after that nothing.

 

Other stealth a/c, like the B-2, F-22 etc use combinations of sstealth technology in difference bits of the a/c. So, wings and tails are alligned as in the 117.

[britgliderpilot]

It's not that simple - such a proposed receiver would be subjected to radar reflections from other aircraft, chaff, jammers/ECM, missiles, clouds, birds, atmospherics or even the ground/sea, all of which would produce MUCH more powerful radar returns than those bouncing off a RAM coated stealth aircraft.

 

Furthermore, even if you manage to filter out the clutter and pinpoint that very weak signal amidst the mess in things, you're still tracking your target passively, not actively. That denies a large fraction of what your software and processing units can do, compared to actively tracking a target. In fact, I'd be interested how you can even derive range information without the use of datalink/triangulation.

 

Finally, perhaps the worse thing is that you'd actually have to have a huge, powerful radar flood the skies with radar waves in order to bombard these radar stealth targets with RF energy. Such a radar will get pinpointed and made a priority for destruction from the moment the system turns its radar on - either from a HARM if it's ground based or an AIM-120 through it's tailpipe if its airborne.

 

. . . As you correctly point out, it'd have to be rather carefully done :P

 

However, I've heard a little bit about what modern systems guys can do with their magic boxes, and I remain confident that if you handed BAE Systems or similar a blank cheque, the boffins could write the code to make it work ;)

 

And you can always substitute lots of little radars for one big one, of course. Do clever enough things with those and it might even simplify matters.

 

 

Such a system may have worked against the F-117, which can only carry LGBs. Against an opponent armed with long-range missiles (like F-35 or B-2) or a kinematically challenging opponent (like the F-22), it would get destroyed within the opening seconds of any conflict.

 

Even against the F-117, there's nothing to stop it from simply flying around the radar receiver array on the ground, or friendly fighters saturating the system with TALD decoys and HARMs.

 

All true - it's still a fixed system as envisaged so far, and as such is always vulnerable to long range weapons. So it wouldn't be terribly useful or survive very long . . . but it'd still be possible to build it.

 

And the F-117 carries JDAMS these days, too.

[Slaunyeh]

AFAIK stealth technology depend on 2 factors :

1) Absorbing material

2) Scattering the incoming RW so it won´t bounce back to the incoming direction.

 

Radar work like a lightray on a mirror, you will only receive any signal back if the lightray hit the mirror in an angle it can be noticed form the emitting point.

 

But as sayd before complications arise. any object will send RW back, birds , clouds, rain, skydivers. (picture that your skydiving having fun with friend then of nowhere a patriot is lauched at you...)

 

To avoid lauching SAM at seagulls and unfortunate skydivers, or having a radar flooded by to much info, there´s a fine tunning to be attained.

 

the obj of stealth tech is to lower quantity of radar waves being send back to receiver position in such a way it will be considered irrelevant by the software analysing received waves.

 

This coud of course be countered by triangulation having a widespread array of RW receivers so you can filter and pinpoint in a better way. But its awesomely costly.

 

This was more or less the approach used by Russian earlier when SU and MIG did not have radar emitter the info being provided from a web of ground mobile/static radars.

 

But this tactic was put in check mate by long range HARM and AAM, that could easely take down airplanes or radar emiters from too far away, eating the array by the borders or even pushing holes in the array with deep strikes leaving airplanes blind and air control with blind spots. This tactic also had another problem, radarless airplaines where unable to enter much ennemy territory.

 

The new radar Russian had boasted before the Berlin wall fall was an attempt to 3d wave reception of diferent lenght waves.

USA boasted it Failed having made stealth incursion undetected and CCCP never said anything about those declarations, since it would unwise to broadcast failure or success.

[GGTharos]

You guys are forgetting something. Stealth is part of a system - while it functions all on its own, it will be implemented together with airborne decoys, counter-measures like chaff, and stand-off jammers, as well as non-stealth aircraft.

 

Good luck finding and attacking the stealth fighter in that soup!

 

As for triangulating the position of a stealth fighter - good luck making particularly effective use of this in combat.

[Pilotasso]

As far as I could understand the EMCON management of F-22's it is designed to minimize electronic exposure BEFORE your are dectected. An F-22 will never open up all the electronic bells and whistles when the enemy is not even aware that they have company. F-22 will use radar in passive mode (data handed over by some other aircraft) and not use any jammers (does it have any besides the AESA array?) not even chaff or flares, at all, including when launching BVR missiles. And thats going the safe way. As far as I can tell it could operate the radar in LPI mode and still not be detected because there arent any counters to LPI yet.

[GGTharos]

Yes there are. They're not operational, but the theory's solid and it's out there accessible by the public - not necessarily -easily- accessible (IIRC it's a science paper type thing, you need access to a specific journal) but it's there.

[Pilotasso]

My brother was also briefed about this when he was in the states. He told me some of the stuff I said appart from that I already knew. The fact that they are not yet operational still makes what I said valid. It could be several years before it does.

[D-Scythe]

What I was thinking was that the system of passive radar recievers would have a datalink with aircraft and ground based radars, not a giant radar of it's own, thus making it invisible to the enemy.

 

So you're gonna sacrifice these perfectly fine ground-based radars and friendly fighters, offering them up for destruction so that your passive receivers on the ground can detect where that enemy F-22 flight is?

 

Sure, the receivers might be invisible to the enemy, but the point is, your radar source is not. Telling your SAMs and fighters to leave on their radars is ludicrous - you're gonna get them all killed.

 

The system would know where a radar, airborne or groundbased, was directing its beam and what information it got back, anything showing up on the screens of the radar emitting sources would obviously be filtered out, what would be left would therefore be reflections of objects "invisible" to the regular radar systems.

 

Doppler radars by their nature filter out almost any clutter. Your receiver array would still be receiving signals from a billion different sources that would never "appear" on the scope of a fighter or ground-based radar, simply because it has been detected, but filtered out. A very good example is chaff.

 

Therefore the system is in effect active, even though it does not have a radar of its own.

 

For your theory to even work on paper, all the radars in an entire military would have to in effect act as one giant radar. The whole system would have to be glued together with some insanely fast datalink, to achieve what is basically a giant AESA radar, where each radar is analagous to a a T/R tile and your receivers scattered all over the place to "catch" RF waves that might be reflected off stealth fighters.

 

And there is STILL the problem that an F-22 or F-35 would know, pinpoint and destroy any radar emitter long before it's been detected, by virtue of the 1/R^2 vs. 1/R^4 rule - that is, radar waves arriving at a stealth fighter is at 1/R^2 strength, but that same radar wave after being reflected off the stealth fighter (in whatever direction) back to a receiver would be of 1/R^4 strength. Technically, it'd be at (1/R^2)(1/R'^2) strength, where R' is distance to your receiver(s).

 

(And that assumes perfect reflectivity of the radar waves - even non-stealth fighters like an F-15 would reflect only a very tiny fraction of radar waves back at the source - in reality, it'd be closer to something like 1/(X*R^4), where X is some constant with a ridiculously high value)

 

Thus, the stealth aircraft would always know that it's being painted by an enemy radar before it will be detected.

[D-Scythe]

And you can always substitute lots of little radars for one big one, of course. Do clever enough things with those and it might even simplify matters.

 

I agree that it's possible. But there really is no difference between one big radar or a bunch of smaller radars - they're all gonna get destroyed in short order by ARMs or GPS guided weapons.

 

And the F-117 carries JDAMS these days, too.

 

Well, F-117s are being phased out of service, so it's really a moot point :p

[monotwix]

Hi:)

I wouldn’t know how to counteract stealth aircraft but is it true that there are infrared cameras that can detect heat differential as little as 0.1 degrees or less or is this a myth?

If not than wouldn’t there be a visible trail couple of miles long in the sky?

And than laser finders, what are they and can they generate a detection arch?

I'm curious.

[golfsierra2]

The F-117 would, in all probability, have been detected by Soviet radar at close range - but the key point to understand is that it would NOT have been detected by Soviet radar in time to prevent it dropping it's weapons (i.e. if it was detected, lock and launch could not have been achieved before bombs away). And that's what mattered.

 

Energy scatter is THE main factor in stealth. If there are now reflections or only very weak, you wont see that bird on a radar set except at very close ranges. This is true for all radar frequencies.

 

About RAM you have to consider, that this material is only good at a certain predefined frequency bandwidth. RAM designed for 'eating' L-band is no good at K-Band.

 

The Russians were / are still good in operating a great variety of radar systems of several generations, from the 50ies to current state-of-the-art, which provides a very large spectrum of radar frequencies to be used. RAM can't cope with all of them at the same time.

[Slaunyeh]

You guys are forgetting something. Stealth is part of a system - while it functions all on its own, it will be implemented together with airborne decoys, counter-measures like chaff, and stand-off jammers, as well as non-stealth aircraft.

 

Good luck finding and attacking the stealth fighter in that soup!

 

As for triangulating the position of a stealth fighter - good luck making particularly effective use of this in combat.

 

 

The dream of any defense system is a stealth jamming...

Lock on jammer....fire, there we go. Sources of jammers are lockable, they present a pattern of movement that can be traced, thats a reason modern stealther have very low IR sign too.

 

BTW all planes with RWAM (not the official name but called i call them Radar Wave Absorbing material) material are being shut down. Why ? RWAM is extremely costly, extremely toxic, and have a very tinny bracket of temperature tolerance.

If you want to maintain RWAM planes on working conditions, you got to put them on the fridge.

[GGTharos]

The dream of any defense system is a stealth jamming...

Lock on jammer....fire, there we go. Sources of jammers are lockable, they present a pattern of movement that can be traced, thats a reason modern stealther have very low IR sign too.

 

I'll repeat what I said then ... stand-off jammers.

 

BTW all planes with RWAM (not the official name but called i call them Radar Wave Absorbing material) material are being shut down. Why ? RWAM is extremely costly, extremely toxic, and have a very tinny bracket of temperature tolerance.

If you want to maintain RWAM planes on working conditions, you got to put them on the fridge.

 

Actually, most stealth or LO aircraft use some form of RAM. Some aircraft require a complete coat of paint, some ... you just dab the leading edges. And there's been much progress made towards easing maintenance of stealth aircraft as well over the time of their development.

[Slaunyeh]

I'll repeat what I said then ... stand-off jammers.

 

 

 

Actually, most stealth or LO aircraft use some form of RAM. Some aircraft require a complete coat of paint, some ... you just dab the leading edges. And there's been much progress made towards easing maintenance of stealth aircraft as well over the time of their development.

 

 

Yeah, but RAM, still have a small bracket of temperature allowance (for long period of time) and the ones that are being put to rest are the fully coated planes. AFAIK