Forum: General F-22A Raptor forum

Given that an AESA radar has a low probability of intercept, is operating on multiple frequencies simultaneously and is changing frequencies more than 1000 times per second, would an enemy aircraft even know that it is being scanned by its radar? I know that it would be very difficult to jam the Raptor's radar, but would an enemy pilot know that he is being scanned by a radar? Let's assume we're talking about a fairly advanced 4++ gen aircraft here.

I also have a question about how the Raptor guides missiles. I'm assuming that the Raptor has a mode that allows it to direct an AMRAAM to its target? When the Raptor is guiding the missile, is it no longer in AESA mode? Or can it guide the missile to the target while simultaneously tracking targets in AESA mode?

Assuming the enemy aircraft has a decent RWR, the pilot would know when he's been locked up by a radar guided missile, right? Would he have any idea of where the lock is coming from? Obviously, locating the Raptor wouldn't be as pressing as evading the incoming AMRAAM, but would he at least have some idea about which direction the missile is coming at him from? For the duration that the radar guided missile is guiding towards the target, is the Raptor essentially unstealthed (after the weapons bay has closed back up)?

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Well knowing your being 'scanned' by radar would require the aircraft to have radar warning receivers. I also think your slightly confused about AESA radar...it is not a mode, but a type of radar. Here is information from the vendor: http://www.es.northropgrumman.com/solut ... index.html

The raptor (or any of our AMRAAM equipped fighters) doesn't guide it's AMRAAMs like a sparrow. It provides updated target info via datalink up till the missile goes active, not through continuous illumination of it's target.

If you want some insight on how a stealth fighter will operate, read up on how our attack submarines operate. It's frighteningly similar.

checksixx wrote:

Well knowing your being 'scanned' by radar would require the aircraft to have radar warning receivers. I also think your slightly confused about AESA radar...it is not a mode, but a type of radar. Here is information from the vendor: http://www.es.northropgrumman.com/solut ... index.html

As Light stated, I was mistaken about the way the AMRAAM is guided. I thought it was guided like a Sparrow....with continuous illumination from the aircraft's radar. I figured that a missile couldn't make use of an AESA radar's guidance because it couldn't operate on multiple frequencies etc.

Regarding RWRs, would most of them be able to detect an AESA radar? Could they distinguish the radar emissions of the AESA unit from the background EM noise? And could they detect the changing frequencies 1000+ times per second?

icemaverick wrote:

checksixx wrote:

Well knowing your being 'scanned' by radar would require the aircraft to have radar warning receivers. I also think your slightly confused about AESA radar...it is not a mode, but a type of radar. Here is information from the vendor: http://www.es.northropgrumman.com/solut ... index.html

As Light stated, I was mistaken about the way the AMRAAM is guided. I thought it was guided like a Sparrow....with continuous illumination from the aircraft's radar. I figured that a missile couldn't make use of an AESA radar's guidance because it couldn't operate on multiple frequencies etc.

Regarding RWRs, would most of them be able to detect an AESA radar? Could they distinguish the radar emissions of the AESA unit from the background EM noise? And could they detect the changing frequencies 1000+ times per second?

No. The APG-77 is called LPI (Low Probability Intercept) for a reason.

Lightndattic wrote:

The raptor (or any of our AMRAAM equipped fighters) doesn't guide it's AMRAAMs like a sparrow. It provides updated target info via datalink up till the missile goes active, not through continuous illumination of it's target.

If you want some insight on how a stealth fighter will operate, read up on how our attack submarines operate. It's frighteningly similar.

So from the enemy pilot's point of view, he wouldn't hear a radar lock tone when the Raptor first locks him right? He might get some indication when the Raptor's weapons bay opens up and it briefly shows up on radar. But he wouldn't know that the AMRAAM is coming until it goes active. At that point, he would have very little time to react. Is that correct?

You might get a faint blip for a second or two when the doors are open, but event that is iffy depending on your angle vs the F-22.

icemaverick wrote:

Lightndattic wrote:

The raptor (or any of our AMRAAM equipped fighters) doesn't guide it's AMRAAMs like a sparrow. It provides updated target info via datalink up till the missile goes active, not through continuous illumination of it's target.

If you want some insight on how a stealth fighter will operate, read up on how our attack submarines operate. It's frighteningly similar.

So from the enemy pilot's point of view, he wouldn't hear a radar lock tone when the Raptor first locks him right? He might get some indication when the Raptor's weapons bay opens up and it briefly shows up on radar. But he wouldn't know that the AMRAAM is coming until it goes active. At that point, he would have very little time to react. Is that correct?

RWR's give a lock on tone warning when a radar painting it shifts to high Pulse Repetition Frequency (PRF), essentially pouring more radar energy onto it and sweeping it more often. I'm using complete conjecture here, but the APG-77 (and theoretically any AESA radar) wouldn't blast a target with a high PRF beam. Since an AESA can scan many times more volume of sky at a time, it would simply update the target's position in the regular mode. This would give the fire control enough of a target track info to launch on. Also, there are other sensors on board that theoretically could give enough info to fire a missile also.

As for a radar spike when the bays open, yes there would be a brief spike IF the target's radar was sweeping it at the time and if our raptor pilot was trying to fire from the front quarter of his target. Again, going back to the sub warfare analogy, the Raptor's stealth and first look advantage will allow it (or the wingmen with it) to maneuver unseen around it's target's radar envelope and get into the most advantageous firing position before opening the bay doors to first off a missile.

If our daring RAPTOR pilot does everything correctly, the first indication an enemy pilot SHOULD have is when the missile's radar goes active, usually seconds before impact.

AMRAAM's INS assisted by GPS and updated by data link is designed so that when it arrives at it's programmed destination, the bandit should be detected once the missile's onboard radar goes active. At least that's the way I understand it.

I also wouldn't be surprised if the Raptor's own RWR was integrated to time the bay doors opening to when the opposing radar sweep wasn't pointed at it. That may not help against another AESA, but against a mechanically scanned dish there may well be no blip from the doors opening.

I'd imagine the radar in the AMRAAM's nose is guided by control laws such that it orients itself in the correct direction pre-programmed into the inertial autopilot so that there is no longer a need for the active radar head to scan volumes of space to obtain a lock. It just turns on and the target is there in front of it...or its not if the AMRAAM isn't updated on the bandit's vector appropriately when on its midcourse. Is this correct?

This from the F-35 wiki, with a reference that I couldn't follow up on:

"The CATbird avionics testbed for the F-35 program has proved capable of detecting and jamming F-22 radars.[223]"

The F-35's sensors are FAR better than any 4.75/4++ gen fighter, but all the same, it does seem possible to at least detect F-22 radar emissions.

When quoting Wiki make sure you pay attention to the references.

223. ^ David A. Fulghum, Bill Sweetman, Bradley Perrett and Robert Wall. "Stealthy Chinese J-20 Vulnerable." Aviation Week, 14 January 2011.

icemaverick wrote:

Given that an AESA radar has a low probability of intercept, is operating on multiple frequencies simultaneously and is changing frequencies more than 1000 times per second, would an enemy aircraft even know that it is being scanned by its radar? I know that it would be very difficult to jam the Raptor's radar, but would an enemy pilot know that he is being scanned by a radar? Let's assume we're talking about a fairly advanced 4++ gen aircraft here.

I also have a question about how the Raptor guides missiles. I'm assuming that the Raptor has a mode that allows it to direct an AMRAAM to its target? When the Raptor is guiding the missile, is it no longer in AESA mode? Or can it guide the missile to the target while simultaneously tracking targets in AESA mode?

Assuming the enemy aircraft has a decent RWR, the pilot would know when he's been locked up by a radar guided missile, right? Would he have any idea of where the lock is coming from? Obviously, locating the Raptor wouldn't be as pressing as evading the incoming AMRAAM, but would he at least have some idea about which direction the missile is coming at him from? For the duration that the radar guided missile is guiding towards the target, is the Raptor essentially unstealthed (after the weapons bay has closed back up)?

The Raptor's radar is a low probability of intercept design. This means that it can discreetly scan for targets, with a high likelihood of avoiding detection. This isn't to say that detection is impossible, but it makes it much more challenging for a foe, to detect, identify, and geo-locate. If a foe's RWR hasn't detected the scans, then it's not going to know if it's been locked onto by the nature of the way the AESA radar works(it doesn't stop frequency hopping, or go into a continuous waveform). In theory, a Raptor could engage 6 targets simultaneously, as each AMRAAM can engage separate aircraft. After the missiles are fired, the bay doors are closed. The entire process takes place in a matter of seconds. There are other means that the Raptor can use to engage targets as well, aside from actively emitting.

-third party targeting(another aircraft platform is doing the emitting, and providing the guidance for the missiles, allowing the Raptor to remain EMCON)
-passive engagement using information from the ESM systems(if the enemy is emitting)
-Home on Jam/ARM modes

Forum: General F-22A Raptor forum

Question about the Raptor's radar