AIM-120C

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Raptor_One

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Unread post11 Oct 2007, 01:58

PhillyGuy wrote:
Raptor_One wrote:Even if you had the target locked up in single target track mode which would no doubt make its RWR light up like a Christmas tree, you'd still have to update the missile's flight path via data link.


Not if you have LPI AESA, then you have two options. Active missile seeker which would warn the enemy aircraft (for however short a time). Or use a super accurate AESA system to guide all the way without any notice whatsoever. I’d still pick the former but the latter is an option just in case…


So you're trying to tell me that the AMRAAM can be guided all the way to its target via data link? I've never heard of that capability at anytime, anywhere. If it actually does have this capability, I can't imagine it being in the public domain. Care to provide a link or properly cited reference to the source of this claim? By the way, I don't believe there's anything THAT special about an AESA radar (let alone one in LPI mode) that makes guiding an AMRAAM via data link (when it's at the end-game stage) a feasible, accurate alternative to using the missile's on-board radar.
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_Viper_

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Unread post13 Oct 2007, 14:50

By the way does the Raptor's opponent know that AMRAAM is coming? AMRAAM's pdf reference, which can be found at downloads section, says that the pilot sees its only when it goes active. If it is so it might give a small chance to survive. Although I have read interviews that some pilots didn't know that they were shot down by the Raptors. Hopefully I'm not asking any kind of classified data.
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Unread post13 Oct 2007, 20:04

Raptor_One wrote:
PhillyGuy wrote:
Raptor_One wrote:Even if you had the target locked up in single target track mode which would no doubt make its RWR light up like a Christmas tree, you'd still have to update the missile's flight path via data link.


Not if you have LPI AESA, then you have two options. Active missile seeker which would warn the enemy aircraft (for however short a time). Or use a super accurate AESA system to guide all the way without any notice whatsoever. I’d still pick the former but the latter is an option just in case…


So you're trying to tell me that the AMRAAM can be guided all the way to its target via data link? I've never heard of that capability at anytime, anywhere. If it actually does have this capability, I can't imagine it being in the public domain. Care to provide a link or properly cited reference to the source of this claim? By the way, I don't believe there's anything THAT special about an AESA radar (let alone one in LPI mode) that makes guiding an AMRAAM via data link (when it's at the end-game stage) a feasible, accurate alternative to using the missile's on-board radar.


Yes, Raptor One, that is a possibility. Here's a quote from Jane's on the topic:

"In April 2006 Boeing announced that together with the US Navy it had conducted a test firing of an AMRAAM (AIM-120B) guided by an Active Electronically Scanned Array (AESA) radar. The missile was fired by a Block II Super Hornet, equipped with an APG-79 radar. The radar tracked the manoeuvring target throughout the missile's flight and provided datalinked targeting updates."
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_Viper_

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Unread post13 Oct 2007, 20:23

If I'm right when using the AN/ALR-94 the amraam does't have to go active so the strike is very surprising. This might be wrong because it is based on my deduction about this system. At least I have read that some pilots didn't know how they have been taken down. A some kind of confirmation would be nice that someone won't actually take this seriously with out a proper confirmation.:?:

And according to vectorsite.net: "A BAe Systems AN/ALR-94 passive receiver system... ...It can detect emitters at ranges beyond that of the AN/APG-77 radar, cue the radar onto the target, or provide direction for AMRAAM attacks against an emitter without use of the radar system at all."
http://www.vectorsite.net/avf22.html
Probably in a Super Hornet's case the high tech AN/ALR-94 is replaced other kind of passive receiver system which provide data link updates I guess..
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seat_dreamer

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Unread post13 Oct 2007, 22:11

Well, the AN/ALR-94 is part of what called "sensor fusion" goodies of the F-22. So, if the radar is not in need to be used, and the "RWR" can guide via datalink the Slammer even in terminal stages, then for sure you won't have the other guys' RWR pick up anything. Unless they have a way to detect Link-16 transmissions (do F-22s use Link-16 or something more sophisticated ?), which I believe is not the most widely available-tech nowadays...
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Unread post14 Oct 2007, 07:20

4Skunky wrote:Yes, Raptor One, that is a possibility. Here's a quote from Jane's on the topic:

"In April 2006 Boeing announced that together with the US Navy it had conducted a test firing of an AMRAAM (AIM-120B) guided by an Active Electronically Scanned Array (AESA) radar. The missile was fired by a Block II Super Hornet, equipped with an APG-79 radar. The radar tracked the manoeuvring target throughout the missile's flight and provided datalinked targeting updates."


The above quote in no way implies that the AIM-120B's onboard radar was never used. Unless the AIM-120 is fired from relatively short ranges (10 miles or so), it is guided through the initial portion of its flight via datalink updates from the shooter aircraft. I don't know how the missile determines when to turn on its own radar, but it will go autonomous once the conditions are right. It will turn on its own onboard radar for the final portion of its flight. And again, there is, to my knowledge, nothing so special about an AESA radar that makes it more capable of guiding an AIM-120 via datalink all the way to its target than a legacy fire control radar. Neither system is going to give the AIM-120 superior targeting data via datalink all the way up until impact compared to its own onboard radar.
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Raptor_One

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Unread post14 Oct 2007, 08:15

seat_dreamer wrote:Well, the AN/ALR-94 is part of what called "sensor fusion" goodies of the F-22. So, if the radar is not in need to be used, and the "RWR" can guide via datalink the Slammer even in terminal stages, then for sure you won't have the other guys' RWR pick up anything. Unless they have a way to detect Link-16 transmissions (do F-22s use Link-16 or something more sophisticated ?), which I believe is not the most widely available-tech nowadays...


The radar in the AIM-120 is specifically designed to detect, track, and kill its prey once within range. If the target aircraft attempts to jam the missiles radar, it can home on the source of the jamming signal until its onboard radar can burn through the music. The AIM-120 will not guide itself all the way to the target by homing in on the target's jamming signal. It will use the jamming signal as a beacon so that it can get close enough to use its own onboard radar which provides much better tracking data. Using an AIM-120 in a completely passive manner would simply lower its PK (probability of kill) by depriving it of precise tracking data supplied by its own onboard-radar. The AIM-120 is not a HARM nor is it a purely command-guided missile. I think people are forgetting what a big deal it was to have missiles with their own onboard radars back in the day. Fire and forget was a really big deal even though missiles like the AIM-54 and AIM-120 weren't completely fire and forget. They were only fire and forget at relatively short ranges where the missile's onboard radar was capable of tracking the target. Failure to support a missile before its radar was capable of picking up the target on its own wouldn't necessarily prevent a kill, but it had the potential of lowering the PK dramatically if the target deviated from the flight vector it was on at the time of launch.

Oh... and if you want to guide an AMRAAM via datalink all the way to the target, you're most definitely going to have to go into a single-target-track mode. This is NOT a low-probability of intercept (LPI) radar mode since you're continuously illuminating the target. An AIM-120 is not going to hit its target by receiving course updates on its target from a shooter aircraft bugging a target in track-while-scan (TWS) mode. TWS is good enough for mid-course corrections via datalink, but it's certainly not good enough for precise, rapid course corrections needed during the final stages of flight... ESPECIALLY not against a maneuvering target. In my opinion (and what's known about the AIM-120's capabilities supports it), this theory about the AIM-120 being used in a 100% passive mode is poppycock. It's as if people in this thread don't understand why an active radar homing (ARH) missile is a good thing. By the way, anti-radiation missiles have been around for longer than ARH missiles (Vietnam era), but you don't see air-to-air HARMs being fielded on any fighter aircraft. Why is that? Because they're not accurate enough to shoot down maneuvering targets. Well... maybe they could hit the radar on a maneuvering warship, but that's probably the extent of a HARM's capability. The fact is that active radar missile seekers are good things. The beneficial autonomous aspect of such a design greatly outweighs the fact that the weapon is not immune to detection due to its radar emissions. If the target's RWR isn't programmed to detect the AIM-120's onboard radar, it won't be detected at all most likely. If it is detected, the target will have only a few seconds to react if caught off guard. This will likely be the case if the AIM-120 is fired from a stealthy F-22. Chances of survival: minimal.
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Unread post14 Oct 2007, 09:19

If the target's RWR isn't programmed to detect the AIM-120's onboard radar, it won't be detected at all most likely.


Speaking of this, could it be possible that AIM-120's radar signature is already "captured" by opposing air forces and is already updated within their RWR systems?
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Unread post14 Oct 2007, 09:55

Speaking of this, could it be possible that AIM-120's radar signature is already "captured" by opposing air forces and is already updated within their RWR systems?

Well you tell me :D But if we want to speculate and what Raptor One just said if the enemy's RWR isn't programmed to detect AMRAAM's signal then the game would be over very soon. Who knows if this tactic is in use in the USAF exercise where Raptors rule.

What I noticed about Raptor One's answers in that the AMRAAM guided via data link isn't as accurate as it might be when using the fighter's own radar. But still what about my interesting theory few post above when I insisted that the AMRAAM won't use its radar? You probably explained it but somehow I managed to miss your point.

TWS is good enough for mid-course corrections via datalink, but it's certainly not good enough for precise, rapid course corrections needed during the final stages of flight... ESPECIALLY not against a maneuvering target.
But how can the target maneuver if it doesn't know that the missile is actually coming :?:
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Unread post15 Oct 2007, 09:08

4Skunky wrote:Yes, Raptor One, that is a possibility. Here's a quote from Jane's on the topic:

"In April 2006 Boeing announced that together with the US Navy it had conducted a test firing of an AMRAAM (AIM-120B) guided by an Active Electronically Scanned Array (AESA) radar. The missile was fired by a Block II Super Hornet, equipped with an APG-79 radar. The radar tracked the manoeuvring target throughout the missile's flight and provided datalinked targeting updates."


I think you didnt interpret your soucers correctly. The wavelengths used by the launcher aircraft radar do not have enough precision to datalink the missile all the way to the target, neither is the speed of the link. Inertial guidance errors would have to be incredibly accurate as well. Beyond whats possible to fit inside such a small missile.
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Unread post15 Oct 2007, 13:11

Raptor, I think you quoted the wrong guy :p I'm merely explaining to Viper what the phrase he posted would probably mean, and I have no idea - neither I suggest - if the AMRAAM can properly be guided via datalink or radar. :D
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torer

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Unread post15 Oct 2007, 17:54

Pilotasso wrote:
I think you didnt interpret your soucers correctly. The wavelengths used by the launcher aircraft radar do not have enough precision to datalink the missile all the way to the target, neither is the speed of the link. Inertial guidance errors would have to be incredibly accurate as well. Beyond whats possible to fit inside such a small missile.


Right before you launch the missile, it changes search pattern, and concentrate the beam at the target aircraft, getting very accurate data about position, speed and direction..
And yes, the AMRAAM B is updated through datalink after firing about target data..
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Unread post16 Oct 2007, 09:57

:doh: Doh of course its updated about target data, what I mean is that I think it cant hit it with that only.
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Unread post17 Oct 2007, 07:40

Raptor_One wrote:
Oh... and if you want to guide an AMRAAM via datalink all the way to the target, you're most definitely going to have to go into a single-target-track mode. This is NOT a low-probability of intercept (LPI) radar mode since you're continuously illuminating the target. An AIM-120 is not going to hit its target by receiving course updates on its target from a shooter aircraft bugging a target in track-while-scan (TWS) mode. TWS is good enough for mid-course corrections via datalink, but it's certainly not good enough for precise, rapid course corrections needed during the final stages of flight... ESPECIALLY not against a maneuvering target. In my opinion (and what's known about the AIM-120's capabilities supports it), this theory about the AIM-120 being used in a 100% passive mode is poppycock. It's as if people in this thread don't understand why an active radar homing (ARH) missile is a good thing. By the way, anti-radiation missiles have been around for longer than ARH missiles (Vietnam era), but you don't see air-to-air HARMs being fielded on any fighter aircraft. Why is that? Because they're not accurate enough to shoot down maneuvering targets. Well... maybe they could hit the radar on a maneuvering warship, but that's probably the extent of a HARM's capability. The fact is that active radar missile seekers are good things. The beneficial autonomous aspect of such a design greatly outweighs the fact that the weapon is not immune to detection due to its radar emissions. If the target's RWR isn't programmed to detect the AIM-120's onboard radar, it won't be detected at all most likely. If it is detected, the target will have only a few seconds to react if caught off guard. This will likely be the case if the AIM-120 is fired from a stealthy F-22. Chances of survival: minimal.


Not really. You can guide the AMRAAM via datalink updates without or without going to a single target rack mode. The only time when you have to is when you are illuminating the target for semi-active homing. With datalink updates it is essentially command guidance.

The problem is that the Raptor's radar is probably not accurate enough to match the AMRAAM seeker's accuracy (~ 0.5-1.5m). That and its data rate -- especially in LPI multi-target track modes -- may not be all that high.

Most importantly, there is really no reason to do so. If you really want to make it nearly impossible for the prey to do anything simply guide the AMRAAM on datalink updates till it is about 2 seconds from impact before releasing it to active terminal homing. 2 seconds is about 2.5 kilometers from the target. Thats plenty of time and room for the AMRAAM to refine its course and home in for a direct hit. But as far as the target is concerned. Thats only enough time for "Huh? What the... BOOM!"
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Unread post18 Oct 2007, 02:53

Dwight... don't tell me not really! I never said the AIM-120 had to be "guided" in single target track mode. It was obvious from the entire context of my post (not the paragraph you took out of context) that I was saying that if, in theory, you wanted to guide a Slammer all the way to its target via datalink, you'd most certainly have to keep the target locked up in single target track mode. And since that would no doubt "bug" the target, you'd get no advantage out of your "stealthy" -120. As for when the Slammer goes active, neither you nor I know enough about the FCR/datalink/Slammer combined system to say exactly when and under what conditions. Is there a two-way datalink between the shooter aircraft's FCR and the Slammer? I don't know. What I do know is that the pilot isn't the one who decides when the Slammer goes active. The pilot has a display telling him how long he needs to support the AIM-120 until it does go active though. In fact, there are brevity codes to indicate whether an AIM-120 has been supported to high PRF (i.e. the radar mode that the missile uses to detect, lock, and track targets at maximum range) or medium PRF. Medium PRF is used at closer ranges and provides better tracking data, false target rejection capabilites, etc. The brevity code word used for the first (HPRF) case is "cheapshot" and "pitbull" for the second (MPRF). That's all I know.

So chew on that, hypothesize, or whatever, but don't tell me not really. Not really how? You don't know enough about the Slammer to tell me that. And please... please don't quote me out of context like that again. I have a real problem with that.
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