Thread: Computing power and Stealth

Originally Posted by avon1944

True but, their ability maintain and track is very vague at best. Currently "best case" can detect stealth aircraft and place them "somewhere in a square box, thirty miles on a side. Typical, currently is a box that is fifty miles on a side. This is totally incapable for vectoring an interceptor to make a intercept.

Assuming "best" case, and assuming an F22 moving over hostile territory - how feasible is the following...

10 years into the future, an opposing country already has a CAP of (for the sake of argument) a JSF derivative or some other LO aircraft. The radar "tripwire" is able to locate the F22 to the 30mile box. The LO aircraft move into that box, using passive sensors only (i.e EOTS/IRST). Would this be a massive problem for the F22?

Passive sensors aside, would it be fealisible to use AESA mounted on the intercepting fighters as bi or multi-static radars, either between each other or between air and ground, or both? I know this would take an enormous amount of computing power but not beyond the realms of feasibility.

I know the radar on the F22 is frequency hopping, LPI, but still gives out a signal. I know current TWR's/detection methods are not upto the job of detecting the signal at a distance, but in the future this would probably be a more cost-effective counter-stealth weapon.

Lastly, again going back to the "30 mile" box, this might be good enough to vector SAMs into the right area. Equip the SAMs with a LOAL seeker (probably far spectrum IR), program them to search in a particular area. If you put up a salvo of them (in much the same way as the F117 was brought down) and you might have a good chance of an intercept. Naturally these missiles would need to be longer range than current IR SAMs - but SM2 has a secondary infra-red mode, so its fealisible.

This is all really speculative stuff (but that's the nature of this particular thread). Be interested in any ideas as to why none of this would work, lol...

To counter stealth with a monostatic radar, the air defense radar would have to greatly increase its gain at the receiver. The way to do this would be to greatly increase the power of the system. If the target aircraft had an RCS reduction of 1,000 the radar power would have to increase by a factor of 1,000 to detect it at the same range as a non-stealthy aircraft. However, increasing power is easier at long wavelengths-not at the short, rapid frequencies commonly used for fire control. Ultrawide band radar poses a similar problem. An ultrawide band pulse could emit waves at several different frequencies hoping to catch the stealth aircraft at a weak point in its RCS reduction. However, transmitting over a wide band diminishes the power in each band, cutting the efficiency of the radar.

The second issue in discussions of counter-stealth is that stealth aircraft are designed against monostatic radars, the type used in nearly all military systems. Monostatic radar couples the transmitter and receiver at the same place, a process that simplifies the crucial function of distance tracking. In theory, a bistatic radar that placed the transmitter in one location and the receiver in another might be able to pick up what might be called the "trailing" RCS that is directed away from the monostatic radar. However, bistatic radars, while simple in concept, have many fundamental technical and operational issues to overcome, according to John Shaeffer, RCS engineer at Marietta Scientific in Georgia. The receiver antenna beam must intercept its companion transmit beam and follow the transmit pulse which is moving at the speed of light. Unless the transmitter and receiver pulses are synchronized, distance measurement is impossible. Even a workable bistatic radar must then address the problem of how much volume of airspace it can scan at a given power setting in a given time. When the receiver, transmitter, and target are located on a straight line, the receiver can be overwhelmed by the transmitter pulse, which hides the target's radar return. As Shaeffer put it, "This is similar to looking into the Sun for light scattered from Venus."

The RCS reduction of stealth aircraft is difficult to counter. Improvements in radar must go a very long way to match the performance they were designed to achieve against non-stealthy aircraft.

http://www.afa.org/magazine/Feb1999/0299radar.asp

Originally Posted by PubFather

Assuming "best" case, and assuming an F22 moving over hostile territory - how feasible is the following...

10 years into the future, an opposing country already has a CAP of (for the sake of argument) a JSF derivative or some other LO aircraft. The radar "tripwire" is able to locate the F22 to the 30mile box. The LO aircraft move into that box, using passive sensors only (i.e EOTS/IRST). Would this be a massive problem for the F22?

Passive sensors aside, would it be fealisible to use AESA mounted on the intercepting fighters as bi or multi-static radars, either between each other or between air and ground, or both? I know this would take an enormous amount of computing power but not beyond the realms of feasibility.

I know the radar on the F22 is frequency hopping, LPI, but still gives out a signal. I know current TWR's/detection methods are not upto the job of detecting the signal at a distance, but in the future this would probably be a more cost-effective counter-stealth weapon.

Lastly, again going back to the "30 mile" box, this might be good enough to vector SAMs into the right area. Equip the SAMs with a LOAL seeker (probably far spectrum IR), program them to search in a particular area. If you put up a salvo of them (in much the same way as the F117 was brought down) and you might have a good chance of an intercept. Naturally these missiles would need to be longer range than current IR SAMs - but SM2 has a secondary infra-red mode, so its fealisible.

This is all really speculative stuff (but that's the nature of this particular thread). Be interested in any ideas as to why none of this would work, lol...

I doubt it. Long wave radars are very immmobile and always taken out first(cruise missiles). Not to mention IR is no majic counter the range on that is shortened as well. If you fire sams there the Raptor will supercruise at mach1.7 away from the enagement envelope and the missiles will have lost track.

Originally Posted by avon1944

The answer is YES. This is not a cure all for when stealth aircraft are detectible all other aircraft will be detectible like beacons. That means for an attack to suceed jamming must be done. As the jamming becomes more effective or disruptive, stealth aircraft will be the first aircraft to escape detection.
So an aircraft like the F-22, just as the attack package is detected the F-22 will pass over them as the group becomes detectible. Jamming would commence and the F-22 with supercruise will get in position to kill the interceptors as they begin to form up.
The monostatic radar today is nowhere like the monostatic radar needed to detect and track a stealth aircraft. You have to remember the a signal that can detect a F-117 will produced a blip will not detect the F-117 when it moves another meter! Another freqency is needed. So a radar that will maintain a track on a stealth aircraft must broadcast a couple thousand frequencies simultaneously, then sorting out the windows characteristics of each frequency. The circuit logic is still beyond today's technology.

The F-35 uses a new technique to defeat detection. Some areas use not only RAM but also a wire mesh where a voltage is applied. Multiple layers can be used to defeat RF energy. This can be made to defeat specific bands of RF energy, such as very low frequencies.



True but, their ability maintain and track is very vague at best. Currently "best case" can detect stealth aircraft and place them "somewhere in a square box, thirty miles on a side. Typical, currently is a box that is fifty miles on a side. This is totally incapable for vectoring an interceptor to make a intercept.

Adrian

I didnt know the JSF used electric currents for stealth. Can I have a link im quite interested.Not to mention this siwith CURRENT stealth tech. Once computing power starts to get threatening to current gen the new breed will be much better. Not to mention new tehcniques might be used in the future.

Originally Posted by urmomma158

I doubt it. Long wave radars are very immmobile and always taken out first(cruise missiles). Not to mention IR is no majic counter the range on that is shortened as well. If you fire sams there the Raptor will supercruise at mach1.7 away from the enagement envelope and the missiles will have lost track.

Long wave radars are immobile. But if you were dealing with a nation able to build a system as suggested above then they would doubtless have anti-cruise missile defences layered around them.

There would be no requirement for the "tripwire" to be longwave radar either - bi-static radar (like the Silent Sentry system as I understand it) could fulfill the same role, in a more flexible platform. Part of the bi-static system could AWACS/fighter based.

I know IR isnt a magic counter - but remember, IR missiles will not warn the F22 of their presence in the same way as traditional ARH/SARH missiles. The French Mica missile already has some of the charateristics of the sort of missile I mentioned. The F22 could detect them on radar, but that might prove to be a weakness as well - in terms of ELINT/EW assets that your future enemy may possess. A SAM would be flying at Mach 4+... Just some thoughts, not arguing that such a system is currently feasible.. but it might be.

And you later argument about improvements to stealth falls on one keypoint. Counter-stealth will improve as well.

Originally Posted by PubFather

... Part of the bi-static system could AWACS/fighter based.

The difficulty with that is time-synching the emitter to the receiver. Land based systems can be linked with fiber optic cables.

Even using GPS time stamps, you can not get target quality returns. And you have a huge processing problem with both the receiver and the target moving. Honestly, I don't think the algorithms even exist for that problem.

highsea is right. Check this out

To counter stealth with a monostatic radar, the air defense radar would have to greatly increase its gain at the receiver. The way to do this would be to greatly increase the power of the system. If the target aircraft had an RCS reduction of 1,000 the radar power would have to increase by a factor of 1,000 to detect it at the same range as a non-stealthy aircraft. However, increasing power is easier at long wavelengths-not at the short, rapid frequencies commonly used for fire control. Ultrawide band radar poses a similar problem. An ultrawide band pulse could emit waves at several different frequencies hoping to catch the stealth aircraft at a weak point in its RCS reduction. However, transmitting over a wide band diminishes the power in each band, cutting the efficiency of the radar.

The second issue in discussions of counter-stealth is that stealth aircraft are designed against monostatic radars, the type used in nearly all military systems. Monostatic radar couples the transmitter and receiver at the same place, a process that simplifies the crucial function of distance tracking. In theory, a bistatic radar that placed the transmitter in one location and the receiver in another might be able to pick up what might be called the "trailing" RCS that is directed away from the monostatic radar. However, bistatic radars, while simple in concept, have many fundamental technical and operational issues to overcome, according to John Shaeffer, RCS engineer at Marietta Scientific in Georgia. The receiver antenna beam must intercept its companion transmit beam and follow the transmit pulse which is moving at the speed of light. Unless the transmitter and receiver pulses are synchronized, distance measurement is impossible. Even a workable bistatic radar must then address the problem of how much volume of airspace it can scan at a given power setting in a given time. When the receiver, transmitter, and target are located on a straight line, the receiver can be overwhelmed by the transmitter pulse, which hides the target's radar return. As Shaeffer put it, "This is similar to looking into the Sun for light scattered from Venus."

The RCS reduction of stealth aircraft is difficult to counter. Improvements in radar must go a very long way to match the performance they were designed to achieve against non-stealthy aircraft.

Winning the radar game will remain central to American success in future joint operations. Air defense threats have increased throughout the 20th century and will continue to do so in the 21st century. Stealth is no magic panacea, but the edge it offers in the radar game is indispensable. Paired with other advantages from ECM to advanced munitions, the effects of LO multiply and will keep the edge of America's airpower sharp.

http://www.afa.org/magazine/Feb1999/0299radar.asp

Not to mention you can't scan into your enemy's airspace(with bistatic radar you can't look into Taiwan from China) In order to have an effective one you need a lot of receivers which are nthing but easy targets.

Originally Posted by PubFather

Long wave radars are immobile. But if you were dealing with a nation able to build a system as suggested above then they would doubtless have anti-cruise missile defences layered around them.

There would be no requirement for the "tripwire" to be longwave radar either - bi-static radar (like the Silent Sentry system as I understand it) could fulfill the same role, in a more flexible platform. Part of the bi-static system could AWACS/fighter based.

I know IR isnt a magic counter - but remember, IR missiles will not warn the F22 of their presence in the same way as traditional ARH/SARH missiles. The French Mica missile already has some of the charateristics of the sort of missile I mentioned. The F22 could detect them on radar, but that might prove to be a weakness as well - in terms of ELINT/EW assets that your future enemy may possess. A SAM would be flying at Mach 4+... Just some thoughts, not arguing that such a system is currently feasible.. but it might be.

And you later argument about improvements to stealth falls on one keypoint. Counter-stealth will improve as well.

Dont ya think LPI would advance over time. it is already almost impossible for ELINT/SIGINT to pick out an AESA. The Raptor may very well be armed with a EOTS. Besides ever hear of JASSM(you won't be able to stop it) It's a great way to sneak past sams and attack long wave radars. Besides Lockheed and ROke manor are the only ones which have made PCL systems. Roke manor's is inferior since it has less range and can be jammed(cell phone towers). Ever hear of weather control devices? That will mess up your chance of detecting anything on IRST and if the enemy puts one up the Raptor will shoot it down. Also IR only works with current propulsion ,who knows what propulsion wil be made in the future.

Originally Posted by highsea

The difficulty with that is time-synching the emitter to the receiver. Land based systems can be linked with fiber optic cables.

Even using GPS time stamps, you can not get target quality returns. And you have a huge processing problem with both the receiver and the target moving. Honestly, I don't think the algorithms even exist for that problem.

In the speculative nature of this thread, I would imagine the algorithms might be "do-able" (I am not, however, volunteering).

Would the returns from such a system be enough to provide limited info: i.e detection, approx altitude, speed and heading. I understand the problems in getting a reliable "track" or "lock".

Originally Posted by urmomma158

highsea is right. Check this out http://www.afa.org/magazine/Feb1999/0299radar.asp

Not to mention you can't scan into your enemy's airspace(with bistatic radar you can't look into Taiwan from China) In order to have an effective one you need a lot of receivers which are nthing but easy targets.

Interesting article - thank you. With regards to your comments...

I appreciate that bi-static radars would be limited in range - but naturally they would only be a part of the overall radar network; as a defence for high value targets such as airfields.

The key point is lots of receivers, making it harder to knock out the whole network, except by vast expenditure of JASSM or other cruise missiles.

Dont ya think LPI would advance over time. it is already almost impossible for ELINT/SIGINT to pick out an AESA. The Raptor may very well be armed with a EOTS.

I'm sure any of the above are possible. But, again, so might the techs to detect it. For the Raptor to rely solely on EOTS would make the playing field between it and even 4.5 gen aircraft much more level. And thats before we start talking about conformal smart skin arrays.

Besides ever hear of JASSM(you won't be able to stop it)

I have heard of JASSM and although difficult to stop - not impossible.
Besides, one of the greatest uses of stealth is as a SEAD weapon - now we are back to where we started with stand-off cruise weapons that are launched in a non-stealthy way (i.e from wing mounted pylons)...

Besides Lockheed and ROke manor are the only ones which have made PCL systems. Roke manor's is inferior since it has less range and can be jammed(cell phone towers).

Jammers can be shot down - ever heard of "home on jam?"

Ever hear of weather control devices?

Not outside of Science Fiction. No.

Also IR only works with current propulsion ,who knows what propulsion wil be made in the future.

Modern missile tracker are "imaging systems" not like the old heat-seekers, capable of all angle intercept. I believe that some are capable of tracking across the visual spectrum - far ir into ultra-violet. Unless its invisible (through a cloaking shield, perhaps of Romulan design) it will still be detectable.

Unless the new propulsion system works on a radical new system - anti-gravity, warp, telekinesis - I suspect it will produce some form of heat..

Anyways this is getting really silly now.. lol

Couldn't you use a variant of Surface Wave Radar? The Aust SWR Station has a 450+ km reach which is "alleged" to be able to act like a mini OTHR. Its actually referred to a "mini-JORN" - and thus with similar stealth platform tracking capabilities to JORN.

I guess the main issue (like JORN) is integrating the tracking capability into a cohesive FCS/targetting system and into other "holographic" trackers?

Originally Posted by gf0012-aust

...I guess the main issue (like JORN) is integrating the tracking capability into a cohesive FCS/targetting system and into other "holographic" trackers?

Hi Gary, nice to see you here.

Do you think HFSWR will gain the capability to accurately track high altitude targets? I know the US currently uses it for drug interdiction, but that is typically against sea skimming targets operating under the normal radar screen.

Originally Posted by PubFather

In the speculative nature of this thread, I would imagine the algorithms might be "do-able" (I am not, however, volunteering).

It sounds analogous to the "n" body problem to me, lol. Perhaps theoretically solvable, but not in practice.

The target is moving relative to both the emitter and the receiver, which is also in motion relative to the emitter and the target. In 3 axes each, with 6 degrees of freedom of motion (7 if you count changes in velocity) for both the target and the receiver.

This is an extremely complicated problem to solve. I think even with the most powerful computers, by the time you process a single return, it's next week. That's assuming you can even invent the math!