A simple method to engage stealthy target

[Aussie Digger]

Low frequency radar detects air target with an error of a few miles. So ARM locates its signal source also with an error of a few miles. That's why AGM-88E is unable to handle radar frequency lower than 500MHz. This kind of radar is completely safe from ARM.

Wrong. AGM-88E features a millimetric wave radar seeker, a GPS/INS guidance unit AND an anti-radiation homing seeker. Emitting or not, no radar or SAM system is "completely safe" from the AGM-88E.

US-German AGM-88E Advanced Anti-Radiation Guided Missile (AARGM)

 

[My2Cents]

Low frequency radar detects air target with an error of a few miles. So ARM locates its signal source also with an error of a few miles. That's why AGM-88E is unable to handle radar frequency lower than 500MHz. This kind of radar is completely safe from ARM.

You should be correct here, the AGM-88E is too small to mount a directional antenna for wavelengths greater than 60 cm.

However, an aircraft should be able to detect and get a cross bearing on anything over 5 MHz with ease. Then feed the GPS coordinates into a JDAM, SDB, or download to a cruise missile, and shoot. Any radar using those frequencies will require an antenna too large to easily move. At best you would have to disassemble it, then reassemble, check, and recalibrate it at the new location. It is not going anywhere before the warhead arrives.

 

[warmaster2010]

Airplane stealth technology poses a serious challenge to radar detection and missile guidance. But no airplane is invisible to infrared seeker, no matter it's a F-22 or B-2. As long as the friction between moving air and solid surface exists, a sensitive infrared seeker can always detect the thermal difference. The IRST on Su-27 can track a F-22 like target more than 15 miles away. And modern infrared imaging seeker will make any counter-measurement useless. So an AIM-9X can always secure a hit on a F-22 within its range.

Old style radars use very long wavelength. It can detect stealth targets but unable to guide a conventional missile accurately due to its poor resolution(up to a few miles' error). If we combine a medium-range surface/air-to-air missile and an infrared seeker, something like an R-27ET, then it's a stealth target killer. Using datalink or radio command to guide such a missile to the approximate airspace near an F-22, the infrared seeker will finish the rest.

This is a simple method based on existing technology to defeat the stealth aircraft or cruise missiles. Previously people did propose using such a radar to guide fighters to get close to an F-22. Now using such radar to guide long range IR missiles to get close to an F-22 is more meaningful.

dont know about IR missiles effectiveness,but russians say that S-400 missile can defeat stealth fighters.Is that an IR missile?

 

[Aussie Digger]

dont know about IR missiles effectiveness,but russians say that S-400 missile can defeat stealth fighters.Is that an IR missile?

No , S-400 is a radar guided surface missile system and the Russians are hardly likely to publicly admit that their latest and greatest missile system is NOT capable of 'defeating' stealth are they?

Probably wouldn't help their sales pitch very much...

 

[Grand Danois]

Low frequency radar detects air target with an error of a few miles. So ARM locates its signal source also with an error of a few miles. That's why AGM-88E is unable to handle radar frequency lower than 500MHz. This kind of radar is completely safe from ARM.

Can't really agree here. There are two different methods for geo-location at play here. The low-freq radar interrogates a "box" which has a much larger extent than the angular error of the radar. The ARM missile has the angular error from the ESM which remains constant; additionally the accuracy in ground coordinates improve as the ARM approaches the emitter. So they're not analogues.

 

[Grand Danois]

Nope, it is the entire object. This concept does not use reflection, but resonance. That is why stealth shaping has no effect.

I definitely accept in principle the concept that low-freq should work like this vs a fighter-sized object. My objection is that there is little to no evidence of ATC or military radars picking up clean F-117 or B-2 under either war- and peacetime condition, be they assisted by outside assets or not.

Thus I suspect that the problem is being reduced too much by making it a matter of freq and object size alone.

 

[Chrom]

No , S-400 is a radar guided surface missile system and the Russians are hardly likely to publicly admit that their latest and greatest missile system is NOT capable of 'defeating' stealth are they?

Probably wouldn't help their sales pitch very much...

You should however understand what this method of thinking goes both ways.

"Americans are hardly likely to publicly admit that their latest and greatest aircraft system is NOT capable of 'defeating' SAM are they?"

Being myself educated in radiophysics (although certainly not anything near military stealth ) i'm sure there is no way to make effective aircraft stealth in sub-500mhz freq. With some methods signature can be lowered several times, but that is maximum. Shape dont work well at these freq, coating dont work at all, only replacing metal with composites will work. But long waves go straight throu composites to metal - so if there is anything metallic in aircraft (even covered by composites or coating), long wave radar will see it.

Still these radars are not yet accurate enough to guide missile right to target. Last mile 2+ GHz radar should be used.

Thats not even to discuss real F-117/ F-22/ F-35 radar signature in 2+ GHz range. I still cant believe it is smaller than radar signature of stealth cruise missile, which is 20 times smaller and (supposedly) is not such impossible target for modern SAM or aircraft radar.

 

[gf0012-aust]

Thats not even to discuss real F-117/ F-22/ F-35 radar signature in 2+ GHz range. I still cant believe it is smaller than radar signature of stealth cruise missile, which is 20 times smaller and (supposedly) is not such impossible target for modern SAM or aircraft radar.

Physical size has little to do with modern VLO/LO design. It's about shape, its about active and passive signal management for a particular platform.

there are minimal common vectors to compare with cruise missiles and aircraft which have a raft of other sub-systems in place to manage their emissions and signature footprints

 

[gf0012-aust]

Thus I suspect that the problem is being reduced too much by making it a matter of freq and object size alone.

absolutely. there's also a lack of understanding that in some VLO/LO aircraft there is a capacity to "go loud" over friendly airspace - hence you see the oft quoted examples of civil radar or SAMs tracking and picking up these aircraft over friendly space

again, I'd point to a raely cited example of how F-117's were not picked up in WVR on short finals over Saudi Arabia when they (Saudis) had all their ears on.

there are also the known examples of aircraft in the same attack corridor being in WVR, knowing that VLO/LO were in the area (and in some cases converging tracks) and yet not being able to see them electronically or via eyeball)

object size is one of the most misunderstood elements of signal management. a similar situation occurs with subs where the urban myth continues that smaller subs are harder to electronically detect than larger (eg nukes) this is just not so, but the urban myths continue unabated. aerodynamics and fluid mechanics are very close "kissing cousins"

 

[Aussie Digger]

You should however understand what this method of thinking goes both ways.

"Americans are hardly likely to publicly admit that their latest and greatest aircraft system is NOT capable of 'defeating' SAM are they?"

True enough, except the American's ALSO have a demonstrable degree of operational experience and success in employing their LO aircraft designs against the latest SAM systems of their time...

 

[My2Cents]

I definitely accept in principle the concept that low-freq should work like this vs a fighter-sized object. My objection is that there is little to no evidence of ATC or military radars picking up clean F-117 or B-2 under either war- and peacetime condition, be they assisted by outside assets or not.

Thus I suspect that the problem is being reduced too much by making it a matter of freq and object size alone.

ATC and miltary radars (other than OTH) operate of far higher frequencies (1 Ghz to 12 GHz) than those required to spot stealth aircraft using the resonance phenomena (2 Mhz to 12 MHz, depending on target aircraft and aspect).

 

[My2Cents]

absolutely. there's also a lack of understanding that in some VLO/LO aircraft there is a capacity to "go loud" over friendly airspace - hence you see the oft quoted examples of civil radar or SAMs tracking and picking up these aircraft over friendly space

Agreed. Most stealth aircraft will turn on a transponder, to make a nice large easy to see blip, when in safe, congested, friendly air space, like when landing. An avoidable mid-air collision will really ruin your day, especially if you survive it.

 

[Grand Danois]

ATC and miltary radars (other than OTH) operate of far higher frequencies (1 Ghz to 12 GHz) than those required to spot stealth aircraft using the resonance phenomena (2 Mhz to 12 MHz, depending on target aircraft and aspect).

Yes, you addressed this in posts 5 & 13. I may have gotten stuck at stupid on the notion that there are smaller chords than wingspan on an aircraft and you're quickly into the 100's of MHz approaching the GHz range?

 

[gf0012-aust]

Agreed. Most stealth aircraft will turn on a transponder, to make a nice large easy to see blip, when in safe, congested, friendly air space, like when landing. An avoidable mid-air collision will really ruin your day, especially if you survive it.

in the case of the F-117, she also had retractable antenna, at a certain point in the journey they would retact those antenna (3 of them) and go passive. from thtat point on, until they hit a point in the return journey, they would no transmit any signals.

in the case of the saudis, even though they extended and went active, even though they were in WVR, the saudi control towers could not see them until they hit binocular range.

 

[lizs]

However, an aircraft should be able to detect and get a cross bearing on anything over 5 MHz with ease. Then feed the GPS coordinates into a JDAM, SDB, or download to a cruise missile, and shoot. Any radar using those frequencies will require an antenna too large to easily move. At best you would have to disassemble it, then reassemble, check, and recalibrate it at the new location. It is not going anywhere before the warhead arrives.

Some logic is self-contradictory here: once an airplane loses its stealth feature before the enemy, it's not much different from a regular airplane to air defense fire. And how can it survive before it can drop the JDAM ? (if my proposed missile exists)

Further, as far as I know, the phase array radar in ballistic missile defense is the kind of radar working around 300MHz, such as the radar in Aegis system. They are not too big in size if range requirement is not demanding.

 

[gf0012-aust]

Some logic is self-contradictory here: once an airplane loses its stealth feature before the enemy, it's not much different from a regular airplane to air defense fire. And how can it survive before it can drop the JDAM ? (if my proposed missile exists)

1) you assume 1st day of war scenarios where LO aircraft are travelling clean and only using internal weapons release.

assuming that the aircraft releases in high PK ranges, then it means that the enemy has literally seconds before weapons impact. The LO asset after release will not continue to fly dirty - it doesn't have to and it wouldn't. It's also not the only asset downtown when the fight is on.

you're also taking a platform centric view, which is not how war is conducted post 1982.

2) planes don't travel alone - they don't have to do so anymore. even in 1999 the VLO assets were part of a systems event where everything from LACM, SOF, shore bombardment and tactical bombing were run concurrently to assist the mission. In the case of the US that means that other tactical strike are in play, that the broader eprotection and esensor assets like Rivet, Compass etc are up - and it means that they're racetracking and tailgating satellites over the critical target areas. ie they don't go in asleep - and they update enroute.

Further, as far as I know, the phase array radar in ballistic missile defense is the kind of radar working around 300MHz, such as the radar in Aegis system. They are not too big in size if range requirement is not demanding.

again you're looking at platform centric scenarios, these assets (Aegis, AWACs, Rivet, Compass, F-22 and JSF etc ) are or will be co-operative battlespace managers which can run primary or hand off where approp. The planes can be passive all the way to the target if necessary as other assets provide a virtual radar picket capability, if not virtual sensor bubble. One asset does not provide sole sensor support. To do so hilights critical path issues, and thats not how things are planned or prosecuted.

the doctrine has evolved constantly ever since Bekaa.

 

[My2Cents]

Yes, you addressed this in posts 5 & 13. I may have gotten stuck at stupid on the notion that there are smaller chords than wingspan on an aircraft and you're quickly into the 100's of MHz approaching the GHz range?

Yes, there are also smaller cords, but you are also in the range where target shape has effect. Simply put, you do not get the benefit of a minor resonance effect because the beam is now redirected away from the receiver.

A wavelength that is 2x the length or wingspan (whichever is greater) cannot see the reflecting facets from the stealth shaping to interact with them, so stealth shaping has no effect, but the resonance still gives a return. Note, the proper wavelength is critical for this. Too long and the aircraft is totally invisible, even without stealth. To short and there is no resonance and the return signal to noise ratio is too low to use. And if the wavelength gets short enough to use a shorter cord or secondary harmonic will also be getting short enough that the stealth shaping starts to have effect, and the majority of the signal is reflected in a direction away from the receiver.

 

[gf0012-aust]

Yes, there are also smaller cords, but you are also in the range where target shape has effect. Simply put, you do not get the benefit of a minor resonance effect because the beam is now redirected away from the receiver.

A wavelength that is 2x the length or wingspan (whichever is greater) cannot see the reflecting facets from the stealth shaping to interact with them, so stealth shaping has no effect, but the resonance still gives a return. Note, the proper wavelength is critical for this. Too long and the aircraft is totally invisible, even without stealth. To short and there is no resonance and the return signal to noise ratio is too low to use. And if the wavelength gets short enough to use a shorter cord or secondary harmonic will also be getting short enough that the stealth shaping starts to have effect, and the majority of the signal is reflected in a direction away from the receiver.

You get the same issues with signal refraction as you do with resonance.

 

[My2Cents]

Lets get the context of this discussion correct.

You should be correct here, the AGM-88E is too small to mount a directional antenna for wavelengths greater than 60 cm.

However, an aircraft should be able to detect and get a cross bearing on anything over 5 MHz with ease. Then feed the GPS coordinates into a JDAM, SDB, or download to a cruise missile, and shoot. Any radar using those frequencies will require an antenna too large to easily move. At best you would have to disassemble it, then reassemble, check, and recalibrate it at the new location. It is not going anywhere before the warhead arrives.

We were talking about the AGM-88E’s ability to home on wave lengths greater than 60cm. Not about the ability of a 300MHz radar to compromise stealth.

Some logic is self-contradictory here: once an airplane loses its stealth feature before the enemy, it's not much different from a regular airplane to air defense fire. And how can it survive before it can drop the JDAM ? (if my proposed missile exists)

How has the aircraft lost it’s stealth feature?

And the JDAM was the shortest range option I listed, so why insist that that is the only one? With equal receivers the aircraft can detect that radar transmitter at twice the range the radar can detect the aircraft, it’s simple math. Just pick a weapon that never requires you to get in range of the defenses. Tomahawk cruise missiles can do it, or send the coordinates back to the Pentagon and they can send in a conventionally armed ICBM, or a SEAL team overland. There are lots of options besides JDAM.

Further, as far as I know, the phase array radar in ballistic missile defense is the kind of radar working around 300MHz, such as the radar in Aegis system. They are not too big in size if range requirement is not demanding.

Not sure which radars you are talking about. Aegis is L and X band (1GHz and up). Most of the others are also X band. The exception is the OTH radars used for launch warning, but those are HUGE.

 

[Chrom]

True enough, except the American's ALSO have a demonstrable degree of operational experience and success in employing their LO aircraft designs against the latest SAM systems of their time...

When and where? Last time i remember it was around Vietnam era, and i wouldnt call it "success against SAM".