AIM-120 seeker lock and AIM-7 Flood mode question

[Seaeagle]

Whatever the case, the AWG-9 radar would only be able to support 1 SARH engagement at a time if it did have that option.. And if doing so, would not be able to provide tracking guidance on any other target during this engagement. The mechanically scanned antenna would have to stay fixated on the target in order to support a SARH missile, and thus could not perform tracking on anyone else.

 

Correct.

 

(and thus couldn't provide mid course guidance for the 5 other -54s it's supposed to be able to support at the same time)

 

Do you think engaging 6 targets simultaneously is mandatory for all situations?

[Frostie]

yeah, but there's a lot of pilots who'd freak out and maneuver regardless of the signal strength. Sure a 51st driver (or whoever on here who would say otherwise) would know better, but many pilots online wouldn't.

 

It would also work pretty well against a head on target to get him/her to defend and lose energy.. Not just in a chase.

But the level of guys you're talking about are basically fish in a barrel on servers, they constantly fly into sub 10nmi 120s and never stray from the blinkered flying of straight to bulls to engage whatever's there. Why would you need to start outwitting them, if you're chasing one just turn your radar off, sure enough he'll turn back in looking for more targets. No disrespect to them because we all started somewhere but I wouldn't even class these guys as kills. It's a level of player that keeps asking themselves, why do I keep getting a last minute warning (those F15s use TWS don't you know).

I don't see someone going defensive from it head on, with seeker unable to even lock over say 10nmi, in a Russian aircraft it would be a very weak signal (considered very long range) probably overridden in favour of your own radar, and in an F-15 it would be an 'M' signal which is obviously not a launch tone and pretty understandable what it is.

[Beamscanner]

You can never guarantee a kill, doesn't matter who your up against. I'd use every tool at my disposal against my enemy. Also, my NCTR doesnt give me any indication of the skill level of the radar contact.. must be broken :)

Also, i'm not entirely sure that the ruskie RWR would ignore the Seeker signal because the F-15 radar is more powerful. The SPO-150 categorizes radar signals by radar type, and will prioritize the signals as such.. Some of those SAM systems are WAY more powerful than the AI radars, but it'll still show you the closest AI radar because it deems it more important.

 

Do you think engaging 6 targets simultaneously is mandatory for all situations?

 

No...?.. but it's something it's advertised to be able to do. In almost all cases the F-14 didn't even fly with 6 -54s.. The point is that, by all indications, the AWG-9/-54 system didn't require any illumination of the target(which would otherwise spook the target to a missile launch) as seen with SARH engagements.

Edited February 4, 2016 by Beamscanner

[ShuRugal]

If all you want to do is spoof your bandit into thinking you've launched, FLOOD mode is great for that (or will be once they fix it again).

 

But, generally speaking, it's better to just go ahead and shoot. If he's good enough to evade a live -120C shot in good parameters, he's good enough to know better than to hit eject when the RWR starts screaming. If he's not good enough to know better than to yank the stick out of the floor, your 120 will kill him.

[AussieGhost789]

You can never guarantee a kill, doesn't matter who your up against. I'd use every tool at my disposal against my enemy. Also, my NCTR doesnt give me any indication of the skill level of the radar contact.. must be broken :)

Also, i'm not entirely sure that the ruskie RWR would ignore the Seeker signal because the F-15 radar is more powerful. The SPO-150 categorizes radar signals by radar type, and will prioritize the signals as such.. Some of those SAM systems are WAY more powerful than the AI radars, but it'll still show you the closest AI radar because it deems it more important.

 

 

 

No...?.. but it's something it's advertised to be able to do. In almost all cases the F-14 didn't even fly with 6 -54s.. The point is that, by all indications, the AWG-9/-54 system didn't require any illumination of the target(which would otherwise spook the target to a missile launch) as seen with SARH engagements.

 

The priority on the SPO-15 follows the bottom indicator lights from left to right, with the left most being fighter radars. Therefore, a fighter radar will take priority over a SAM (unless the SAM is locking you, in which case it becomes the primary threat and is prioritised). Also, the spo-15 (in game, at least) recognises and prioritises the radars on board ARH missiles.

[fltsimbuff]

 

Whatever the case, the AWG-9 radar would only be able to support 1 SARH engagement at a time if it did have that option.. And if doing so, would not be able to provide tracking guidance on any other target during this engagement. The mechanically scanned antenna would have to stay fixated on the target in order to support a SARH missile, and thus could not perform tracking on anyone else. (and thus couldn't provide mid course guidance for the 5 other -54s it's supposed to be able to support at the same time)

 

I don't know where you get that idea. Multiple sources I've read say the AWG-9 illuminates each target it is tracking periodically for the SARH mid-course guidance of the Phoenix. I don't see any reason the guidance system in the Phoenix couldn't maintain a track of its assigned target with periodic pulses for mid-course, as long as the AWG-9 keeps illuminating at intervals.

[GGTharos]

Multiple sources say that, but it's also a very fishy statement. If it means exactly what it says, then the 54 is counter-measure bait. How does it even know which blip it's targeted at? We know very well that AIM-120 uses the M-link to sort out which target each missile is going for, for example.

 

The reason you don't run 'SARH all the way' at such ranges, but rather use data-link updates is that it takes a lot of power to make that seeker work, as well potentially increasing self-noise due to heating caused by radar operation.

[fltsimbuff]

Multiple sources say that, but it's also a very fishy statement. If it means exactly what it says, then the 54 is counter-measure bait. How does it even know which blip it's targeted at? We know very well that AIM-120 uses the M-link to sort out which target each missile is going for, for example.

 

The reason you don't run 'SARH all the way' at such ranges, but rather use data-link updates is that it takes a lot of power to make that seeker work, as well potentially increasing self-noise due to heating caused by radar operation.

 

Yes. No definitive source one way or the other.... at least not right now. I am saying that this method is as valid as any other put forth, so there's no reason to throw out SARH.

 

I've seen other sources indicate track data is transferred to the missile in flight. We probably won't know until the appropriate docs become de-classified.

 

As far as countermeasures... at the distances mid-course is used, chaff certainly won't be that effective, as the separation between the chaff and the real target will increase quickly. As long as the radar in the fighter illuminates the right target, the AIM-54 will fly toward the right target as the chaff falls out of the resolution cell of the radar. If the chaff is close enough to get illuminated with the target, that's still accurate enough for mid-course. Chaff close enough to the target to fool radar will still put the Phoenix close enough to see the target on its active radar when that comes on. If the fighter's radar is fooled by the chaff instead, that would affect the accuracy of the M-link data as much as using SARH.

 

I read somewhere that the Phoenix needs the target illuminated by the AWG-9 once every 2 seconds, which restricts the scan volume of the AWG-9 to 4 bars/20 degrees azimuth or 2 bars/40 degrees azimuth while providing mid-course to one or more Phoenix missiles. No idea of the accuracy of that statement though.

 

So my point being, there's no reason to throw out SARH guidance. There are still plenty of indications that it was used.

[Seaeagle]

 

No...?.. but it's something it's advertised to be able to do. In almost all cases the F-14 didn't even fly with 6 -54s.. The point is that, by all indications, the AWG-9/-54 system didn't require any illumination of the target(which would otherwise spook the target to a missile launch) as seen with SARH engagements.

 

One does not exclude the other.

 

TWS(up to six targets) ---> INS/command update --> ARH

 

STT(single target) ---> INS/command update --> SARH

[GGTharos]

As far as countermeasures... at the distances mid-course is used, chaff certainly won't be that effective, as the separation between the chaff and the real target will increase quickly. As long as the radar in the fighter illuminates the right target, the AIM-54 will fly toward the right target as the chaff falls out of the resolution cell of the radar. If the chaff is close enough to get illuminated with the target, that's still accurate enough for mid-course. Chaff close enough to the target to fool radar will still put the Phoenix close enough to see the target on its active radar when that comes on. If the fighter's radar is fooled by the chaff instead, that would affect the accuracy of the M-link data as much as using SARH.

 

Chaff is a serious issue, and in fact small separation is often worse than wide. You're completely missing the point, which is all about somehow emulating TWS with SARH-to-ARH guidance. How does the missile know what to choose? :)

 

If there's an M-Link, then what's this SARH business all about? The missile has no need and likely no business operating in any type of SARH mode at this point.

 

I read somewhere that the Phoenix needs the target illuminated by the AWG-9 once every 2 seconds, which restricts the scan volume of the AWG-9 to 4 bars/20 degrees azimuth or 2 bars/40 degrees azimuth while providing mid-course to one or more Phoenix missiles. No idea of the accuracy of that statement though.

 

That's because of the data-link update interval. You get position one second, vector the next. Getting updates every two seconds thus gives you optimal timing for M-link data transfer, and also guards against medium-g target maneuvers.

Longer intervals are possible but not very useful, especially when selecting targets.

[fltsimbuff]

Chaff is a serious issue, and in fact small separation is often worse than wide. You're completely missing the point, which is all about somehow emulating TWS with SARH-to-ARH guidance. How does the missile know what to choose? :)

 

Chaff close to a target hides exactly where the target is. Mid-course doesn't need to be exact, just near enough to see the target when it goes active. The mid-course is irrelevant to sorting out chaff once the missile goes active. So chaff would not be that big an issue for SARH vs datalink. Not saying datalink isn't better, just that SARH is not as big a handicap vs countermeasures as you seem to think it is, at least not for mid-course guidance purposes.

 

If there's an M-Link, then what's this SARH business all about? The missile has no need and likely no business operating in any type of SARH mode at this point.

 

We haven't established there IS a data link. Some sources say data link... more sources say SARH. It certainly would not need both, but we don't know which of the 2 it uses. I am leaning toward SARH because I have seen a lot more in support of that method.

[GGTharos]

Mid-course updates are very relevant to sorting targets out. In fact it is precisely the mechanism used to sort targets out. SARH is a gigantic handicap since you receive zero data on what your target is, and what it is doing - in other words, you have no data to sort with, and for all intents and purposes your choice between the actual target and chaff is luck-of-the-draw.

Not to be confused with actual SARH guidance where the offending radar operates in STT and there is a constant transfer and comparison of doppler shift from that radar to what the missile is receiving (receive ownship signal on tail antennae, compare signal to what's coming into the seeker). At least there you have continuous methods of rejecting chaff. When you're in this w-second flash pick-up, I'm not even certain how you're going to be able to tell what your original target is.

Besides, that missile gets shot at targets so far away that there's no way it does not have an M-link.

[Seaeagle]

 

We haven't established there IS a data link. Some sources say data link... more sources say SARH. It certainly would not need both, but we don't know which of the 2 it uses. I am leaning toward SARH because I have seen a lot more in support of that method.

 

SARH = Semi-Active-Radar-Homing

 

Its a terminal homing method(like ARH) and not an alternative form of midcourse guidance.

[fltsimbuff]

SARH = Semi-Active-Radar-Homing

 

Its a terminal homing method(like ARH) and not an alternative form of midcourse guidance.

 

I know you are trying to be a pedant, but that is *terminal* homing. Guidance further out can still be homing.

[fltsimbuff]

Mid-course updates are very relevant to sorting targets out. In fact it is precisely the mechanism used to sort targets out. SARH is a gigantic handicap since you receive zero data on what your target is, and what it is doing - in other words, you have no data to sort with, and for all intents and purposes your choice between the actual target and chaff is luck-of-the-draw.

Not to be confused with actual SARH guidance where the offending radar operates in STT and there is a constant transfer and comparison of doppler shift from that radar to what the missile is receiving (receive ownship signal on tail antennae, compare signal to what's coming into the seeker). At least there you have continuous methods of rejecting chaff. When you're in this w-second flash pick-up, I'm not even certain how you're going to be able to tell what your original target is.

Besides, that missile gets shot at targets so far away that there's no way it does not have an M-link.

 

Mid-course for the Phoenix is a supplement. It keeps it headed into the "basket" as that "basket" moves. Remember the guidance was designed in the 1950-60s, and the other radar missiles were beam-riders and pure SARH. The Phoenix was an improvement with terminal active homing and autopilot. Target sorting is unlikely going to be a big deal attacking multiple real targets close enough to conflict, especially with the range and angular precision giving a rather large resolution cell for the radar. Velocity measurements can help with chaff sorting, no datalink necessary.

 

What data can the missile not get via the radar reflected from the target that it can get out of the data link? I am talking circa 1950/60. GPS helps in modern times as it is absolute position a GPS-enabled missile can use, not position data relative to the fighter. Azimuth and range data isn't helpful as it is relative to the launching platform, not the missile. Steering commands or any other reference to the target locations require the launching fighter to track the Phoenix too (there's no evidence I've seen that it does, and see below for the reason it probably can't.).

 

Let's look at this another way. Have you seen a diagram/parts list showing a rear-facing data link antenna or wave guide for a datalink? Any indication the AWG-9 tracked the missile as well as the target so it could provide more meaningful updates than target motion deltas? The Phoenix would have a hard time picking up a data link with it's radome pointed away from launching platform without one. Then there's the detail of the Phoenix lofting at altitudes far above where the fighter's radar antenna is ever pointed.

 

It's not a big deal. My opinion differs from yours on this issue, as we have discussed previously, and we can't find definitive proof either way. Let's just leave it at that, and if you ever come across hard data that shows use of a datalink, I'd love to see it.

[Frostie]

The Aim-54 was designed to be a long range bomber destroyer and was designed for multiple target engagements. The awg-9 radar that it was coupled with was able to engage multiple targets through a spot lighting technique. The radar would shift its beam from one target to another (from 1-6) and would cycle through the targets. These would then be fed into an analog computer and the corrections for the AIM-54 were periodically updated ; however, if one of the bogeys changed it’s path and was not in the ‘spot light volume’ when the AWG-9 cycled back to shine the target, both missile and radar would go stupid. In a BVR engagement a bogey could perform a 30 degree check turn and go down to a lower altitude to counter a Phoenix shot. Also, the missile was expensive and hard to maintain. The AIM-54 was a pioneer in that it was the first step towards a long range BVR missile. The AIM-120 made much more sense to equip the future force and was meant to be a cheaper and more effective alternative which could be fired from single seater aircraft(which lacked a RIO). Initially, the AIM-120 ran into a lot of software problems but once the code was worked out became the premier BVR missile for US ac.

 

F-15 Eagle Engaged, Davies, Dildy. pp 87-88

[Fox One]

Have you seen a diagram/parts list showing a rear-facing data link antenna or wave guide for a datalink?

 

Exactly. I also think there is no fighter to missile datalink. Such antenna is nowhere to be found on AIM-54.

 

I think for a AIM-54 very long range shot it works like this: there is an inertial guidance phase, a SARH phase and an active radar phase. The inertial phase is obviously necessary because, as long as the target is not huge, for a long range shot the missile will most likely not be able to SARH it right from the start.

 

So there will be inertial guidance with the missile's antenna looking where it was instructed to look before launch until the missile radar antenna can sense the F-14's radar pulses reflected by target. If during the inertial phase the target makes a significant heading change and it is not within a cone of a certain size where the missile expects to start SARH, the missile is lost. They would probably never make a very long range shot on a suspected small, maneuverable aircraft - too much risk to lose the missile. They would wait for a range where SARH is available right from the beginning.

 

There is data for R-27R SARH seeker. For a 10 sqm target, the seeker will see the target at 40Km. You can easily assume significantly better AIM-54 seeker performance in SARH mode - its antenna has a considerably larger diameter than R-27 and it is a slotted planar array design, much better antenna characteristics than R-27R's archaic type.

[Beamscanner]

One does not exclude the other.

 

TWS(up to six targets) ---> INS/command update --> ARH

 

STT(single target) ---> INS/command update --> SARH

 

IDK what your getting at.. I never said the AWG-9 couldn't perform SARH in STT. I said that it didn't make sense for the AWG-9 to perform SARH guidance on 6 targets(which would require TWS mode) at the same time.

 

The priority on the SPO-15 follows the bottom indicator lights from left to right, with the left most being fighter radars. Therefore, a fighter radar will take priority over a SAM (unless the SAM is locking you, in which case it becomes the primary threat and is prioritised). Also, the spo-15 (in game, at least) recognises and prioritises the radars on board ARH missiles.

 

Yea... I know this. I stated exactly what you said as well... Frostie thought that the fighter radar being more powerful than the ARH seeker would mask it.. I stated that the RWR prioritizes signals by radar type rather than power.

 

I don't know where you get that idea. Multiple sources I've read say the AWG-9 illuminates each target it is tracking periodically for the SARH mid-course guidance of the Phoenix. I don't see any reason the guidance system in the Phoenix couldn't maintain a track of its assigned target with periodic pulses for mid-course, as long as the AWG-9 keeps illuminating at intervals.

 

After having researched details, i have seen a lot of comments suggesting autopilot->SARH mid-course guidance->active terminal.. and not much on a data-link. Though I couldn't find any official resources on the matter.

 

But as we discuss this, we must realize that if this is the case, it's not your typical SARH Lock(at least during a TWS shot). My primary concern on this is really about what indications the enemy will get during a TWS launch of a AIM-54.

 

It is perceivable that the AIM-54 could launch in the blind(INS/autopilot) for a period of time until it reached a predicted range at which its seeker could passively receive radar reflections off the target for some course corrections. Though each of the missiles would have to use its own channel (ie the AWG-9 would change frequencies for each of the missiles seekers) in order to distinguish the reflection of its intended target. However, the missile would have no way to distinguish multiple reflections inside the same "illumination" beam (which is a pretty big beam considering the massive range between the targets and the AWG-9). The missile would likely steer towards either the biggest reflection(which may not be the intended target) or the reflection with the highest positive Doppler shift (the fastest closing object inside the main beam).

 

However, this method alone would not provide range to the target during mid-course flight. I'm willing to bet that the signal being "illuminated" off the target would modulate it pulse timing sequence which the missile could interpret as either an indication of range or a time to pit bull. But this would indicate both SARH (for direction) and embedded information on a signal (i.e. a datalink, for range and possibly other variables)

 

The main reason I want to discourage referring to the guidance method as just "SARH", at least in the context of this game(its not a simulation in the context of Radio Wave propagation, Electronic Warfare, etc..) is that people may expect to receive the same warnings from this missile as from an AIM-7. Which is not the case. The AWG-9 is not contentiously fixating it's emissions on its target. the fact that its scanning plays a significant part into this reasoning. Now of course its possible that some engineer programmed a RWR to freak out if it sees a AWG-9 scanning.. period. but that would mean that it'd go off any time it saw that AWG-9 signal. Regardless of whether it has launched a missile.

 

If I was a betting man, I'd say that the AIM-54 used a combination of "SARH"(though its really not homing to a high degree of accuracy because of the scan periods) with embedded data in its pulse timing sequences(also known as pulse position modulation or PPM for short).

Which would make all of us right and wrong to some extent, if true.

Hopefully Leatherneck sorts this all out for us:)

Edited February 7, 2016 by Beamscanner