The AIM-120 'AMRAAM' - History, Design, Performance & Discussion

[MythicPi]

@Ziggy1989

Aim7F was overpowered on release? Wrong.
It was completely a Mach slower than it was in game and had zero turn capability at close and medium ranges. It was killing nothing upon release. Go look pull up the forums when the F4J came out. They hot fixed it mid patch it was so bad.

You also forgot to mention that the AIM-7F along with all radar missiles had their speedgates nerfed into the ground for about 10-11 months following the release of the F-4J, which made the missile incredibly unreliable and very commonly a teamkilling threat for no good reason at all. This massive nerf to all radar missiles particularly impacted western jets which relied on them to try to even the playing field against the outright oppressive MiG-23 MLD, possibly the most oppressive jet in the last 3-4 years of WT at release.

@Ziggy1989

Want to talk what’s overperforming? R27ER. There is no way in hell a 700lb R27ER can go Mach 4 at low altitude and immediately pull up 90 degrees and fly after any target you decide to relock without losing stability and or energy. It’s not physically possible.

Speaking of the R-27ER, I have an ever growing suspicion the missile is massively overperforming in some aspect (I suspect its drag?). The R-27ER has a lower CkX (1.75) than than the R-27R (2.0) (7M has a CkX of 2.3 btw), and its actually the lowest CkX I could find in-game, granted I only really looked at other radar missiles it would commonly face. Despite the fact it has lower specific thrust for both its booster and sustainer(234.45/233.96) than the 7M(328.23/301.49), which is a measure of how efficiently the engine uses the fuel to create thrust, the ER ECLIPSES every other air to air missile in effectively every metric worth anything, to the point of it being honestly rather absurd, surpassing the total dV of the R-27R(721.84m/s) for example by roughly 66%, and its closest competitor, the AIM-7M(955.94m/s), by ~21%. I’m starting to think its abnormally low CkX is the reason it so vastly outperforms everything else. Not only in acceleration and speed, but also seemingly in speed retention, particularly in maneuvers, which it should DEFINITLY not be doing seeing as its a MASSIVE missile (260mm diameter, 4.7m long) with a shorter burn than something like the 7M.

iirc the 27ER also has a better seeker than any other missile in-game, cuz yanno, reasons. Hence why it seems to be the least affected radar missile when it comes to gaijins current horrendous modelling of things such as multipath. This is despite 2 acknowledged bug reports on separate missiles (the ER and the 7M) indicating the ER has a minimum alt of 20m, while the 7M has a minimum altitude of 5m irl, along with the fact that allegedly, the ER cant even be launched against a target below 3km altitude if there is ground clutter behind them (though this last claim, I haven’t been able to confirm immediately, and will be looking into it some more as it could help everyone deal with the 27ER and end its stupid reign of terror).

[AlvisWisla]

9L all aspect range is 11km on afterburning targets in War Thunder [10km locked for launch, likely a general game limitation].
All missiles have same visual signature, and IDK if that’ll change. That or the diamond will just be based on motor burning instead of smoke.

[MiG_23M]

A capability that was not known until I referenced many different documents and scoured the internet for months before finally submitting a report? Nowhere else is this mentioned with a source worth its’ salt.

AIM-7F was not overpowered on release, sure… but it was certainly overperforming for the vast majority of time it’s been in the game… which has been well documented thanks to my report. This was fixed. And it’s not unique to the AIM-7F either, the R-23R was busted as well and was never a decent missile despite all these fixes. It took the R-24R coming to the game (still inferior to the AIM-7F) for Russia to have a competitive radar missile.

AIM-54C is not even remotely copy paste of the AIM-54A in the same sense the AIM-7E-2 is not a copy paste of the AIM-7E… Idk what this argument was supposed to prove. None of this data for fixing the AIM-54 was available on release. It was discovered via FOIA later.

AIM-9J/P copy paste was well explained and continues to make no serious difference. If they were to model the minute differences it would have net zero impact on the actual performance of both. USAF continued to upgrade the AIM-9P over the years, so if you have proof the AIM-9P-1 and AIM-9J are not identical or whatever, feel free to report it.

Where are you finding the all aspect range of the AIM-9L is nerfed? In fact, I’ve found documents that suggest it’s nearly double the 0 degree head-on lock range that it really should have. We can go ahead and report that and all other IR missiles in-game to have all-aspect lock range significantly reduced in 0 degree head-on scenarios if you’d like… except for the Russian missiles which are well documented and performing accurately already with the exception of the R-27T/ET… they are significantly underperforming in all aspect lock range right now.

Why are you highlighting the “illumination necessary only for mid-course and terminal guidance”? That’s literally the entire flight… what?

Without CW it cannot lock and track in normal SRC mode. It would only be able to lock and track in a HPRF (head-on) lock. This would be a significant nerf.

… disadvantages of being able to switch to SRC and track through a notch?

[MiG_23M]

British documents suggest the all-aspect lock range of AIM-9L against non-afterburning targets should be approximately 1-1.5km iirc. Within 30 degree frontal arc this picks up to about 2-3km or something like that. I’d need to go back and reference them.

[MiG_23M]

@Ziggy1989 Whatever reply you have for me is gonna have to wait to be seen until the morning. Seen you typing up a storm, perhaps its a better conversation to have in DM’s anyway. I’m not seeing anything productive coming from the discussion at this point.

[Ziggy1989]

Wait… you think High PRF above 30 kHz can only lock targets in a head on? No… Lol
OMG you are so wrong.

Almost every single radar missile that is Air to air & Surface to air that was EVER MADE is configured as a high PRF, pulsed doppler radar frequency. Essentially as a Doppler tracker apart from being a basic monopulse angle tracker.

A radar missile, even the most advanced must be configured High PRF (better known as interrupted continuous-wave or ICW) to successfully guide to target. That is why they go “Pitbull” in terminal phase.

A “weapons grade lock” is only achieved in HPRF.

In older aircraft such as the F4 you needed a second transmitter called a CW illuminator to generate a weapons grade lock. Which was the main problem holding the sparrow back in terms of guidance.

High PRF radars do not need an additional illuminator. Their Radars are too powerful and have the field strength to correctly guide sparrows to target with no issue whatsoever.

The F14, F15, F18 and the F16C does not either. But all the same issues that previous generation of fighters had with guiding sparrows is still prevalent.

WT does not know what they are talking about when it comes to radars. Unfortunately, you do not either.

It is pure War Thunder belief that HPRF can only lock targets in head on. What a contradicting belief because you can still kill targets in a chase while in HDN right now in game.

Note: I did not see your additional comment for message until after. But it does not matter. GJ will not move to make the game more realistic if people continue to defend poor modelling and neglect for western weapon systems. Something I do not believe you are capable of ceasing.

[Flame2512]

@MiG_23M

Do you have any examples of how American equipment has come to the game in an intentionally nerfed state?

As far as I can tell you are responding to this bit:

@Ziggy1989

Genuinely asking (anyone), Why does every western missile need 20 active bug reports and half a year and counting for GJ to actually model their missiles?

There are a number of examples I can think of where Gaijin has nerfed western missiles, or done a very poor job of modelling them, with a massive pile of bug reports needing to fix them. I’m sure there are plenty of examples for Russian missiles too, but you asked for examples of western missiles, so here are some off the top of my head.

Intentional nerfs:

• Stinger and Mistral being limited to 10g overload, when there are multiple primary source documents showing both to have more than double that. Nerfed to that level because Gaijin found out the Igla was 10g and didn’t think the Stinger / Mistral could really be that much better than it.
• AIM-9D / G being limited to 16g despite Gaijin being provided with multiple weapons manuals explicitly stating the max g load was 18+g. Kept nerfed at 16g for ages because Gaijin had a secondary source document stating that the MIM-72A was 16g (they never explained why a secondary source about a different missile overruled two primary sources)
• Red Top being modelled without any front aspect capability. Sure you could argue that no front aspect IR missiles were in the game then. But even once all aspect IR missiles were in the game Red Top hasn’t been given a front aspect capability (and yes it does actually have a front aspect capability against sub-sonic non-afterburning targets, you just need to be a little bit off the nose).
• Firestreak was modelled as a 5g missile instead of a 15g missile. After being provided with two different primary source documents Gaijin increased it, but only to 13g. Then after further complaining by the community they increased it to 15g, but removed proportional navigation guidance from it, making it pretty terrible. After even more complaining from the community Gaijin eventually stated they removed proportional navigation from the Firestreak because one of the documents said it was a “pursuit course missile”. After we pointed out that the document they were referring to explicitly stated Firestreak used proportional navigation guidance, and “pursuit course” referred to the type of intercept the interceptor was meant to follow they finally modelled Firestreak correctly. A year and a half after it was added.
• After British players constantly asking for the AIM-9G it was introduced as a copy-paste AIM-9D without radar slaving, or the 40° uncage capability (the only two things to differentiate it from AIM-9D).
• AIM-9L was modelled as a 20 g missile for ages (back when it was only on the AH-1Z).

Bad modelling:

• Pretty much everything else about Red Top when it was added. Seriously everything about Red Top apart from the visual model and missile mass has had to be bug report. There is a bug report on it missing 1/3 of its aerodynamic range, that is still open 3 years on. Along with a whole bunch of other reports.
• AIM-9D was a copy paste AIM-9E (even down to using the AIM-9E visual model when it was added). Gaijin then buffed it way to far in the opposite direction; which while hilarious for British Phantom players kind of destroyed game balance for a while (there is a video of someone getting an 18 km rear aspect kill).
• Gaijin just deleted SRAAM’s guidance for over a month (if you fired it then all it would do is fly in a straight line for 3 seconds then explode)
• After fixing SRAAM Gaijin then broke it again and left it basically useless (spinning out and unable to hit even a slightly maneuvering target) for something like 6 months, only fixing it just before the Harrier GR.1 was revealed (coincidence?)

[MaMoran20]

Oh they know, they just ignored and muuuhh later.
https://community.gaijin.net/issues/p/warthunder/i/qKeCG0nvUksM

Range gated HPRF

They say it has more drawbacks than advantages which is why no modeling has been done. BS, range gate allows tracking through MLC.

[InterFleet]

@Flame2512

AIM-9D / G being limited to 16g despite Gaijin being provided with multiple weapons manuals explicitly stating the max g load was 18+g. Kept nerfed at 16g for ages because Gaijin had a secondary source document stating that the MIM-72A was 16g (they never explained why a secondary source about a different missile overruled two primary sources)

A2A missile and surface to air missile variant have different G overload because the inital launch condition for SAM is 0 velocity, which means that it is not possible to achieve as much G as, for example, AIM-9D launched at mach 0.8 from F8E. Overall the 16G matches the low speed launch diagram found on F4J and is generally correct.

Devs are still reviewing SRAAM and Red Top at the moment, because changing missile flight performance is not as easy as changing the seekerhead FoV…

[InterFleet]

@Ziggy1989

It is pure War Thunder belief that HPRF can only lock targets in head on. What a contradicting belief because you can still kill targets in a chase while in HDN right now in game.

Note: I did not see your additional comment for message until after. But it does not matter. GJ will not move to make the game more realistic if people continue to defend poor modelling and neglect for western weapon systems. Something I do not believe you are capable of ceasing.

Well, there are bug reports at the moment on the rear aspect issue with F4J/missiles , which there are document stating the detection range under various aspect. The main issue I see is the MLC and Altitude Clutter is modelled, However, there is a region between them that most rear aspect targets fall into, (that the radar should be able to pick up) However in game the entire region have the exact same ground clutter as MLC and altitude clutter… making rear aspect detection in velocity search impossible.

Somehow Tornado F3 can detect rear aspect target in PD HDN, but I am not so sure if and when rear aspect detection will be implemented for Velocity Search

[oppsijustkilledu]

RED TOP and it’s still in a nerfed state

[EL337GH0ST]

AIM-9L should have 8.5 km frontal lock on range against afterburning targets, this was reported literally as soon as the AIM-9L came into the game, I can’t find the report because the previous forums had a trash search system

Edit: here’s the report (what a surprise, it’s locked and can’t access it), however, I can see a little bit of text and a picture

[Flame2512]

@InterFleet

A2A missile and surface to air missile variant have different G overload because the inital launch condition for SAM is 0 velocity, which means that it is not possible to achieve as much G as, for example, AIM-9D launched at mach 0.8 from F8E.

I agree with that. It just seemed strange at the time that they were using a secondary source about the MIM-72, rather than the two primary sources they were provided, as:

1. As you say the MIM-72 is ground launched (and has a few modifications)

2. By Gaijin’s standards primary sources should override secondary sources.

As it is they have obviously fixed it to 18 g now (well a while ago)

[Gunjob]

A better break down based on pW/Cm², granted this is for MIL power but gives you a better ideal of tracking capabilities.

Spoiler

[AlvisWisla]

Gaijin is always moving toward more realism through the development of new systems.
We just aren’t told about them cause it’s not our business until it’s ready to be implemented.

@Flame2512
The R-60M had its share of inaccuracies, well over 5 previous inaccurate states. 9L was inaccurate until fixed wing, and share 3 inaccurate states since including the current live version, and the missile is being made more accurate next major.

Everything you listed weren’t intentionally wrong.
Stinger being limited to 10Gs is not an intentional nerf, that’s the start point of ALL manpads, even Mistrals were 10Gs at one point. The 20G historical report is a this year item.
Limited front aspect wasn’t a game feature for a while in general, thus couldn’t be intentional.
Firestreak is clearly misunderstandings in translation.

@EL337GH0ST
Are you arguing that AIM-9Ls are over-performing against front aspect afterburning targets?
Cause currently 9Ls lock at 11km, but you say it should be 8.5km instead.

[Ziggy1989]

My bro has no idea what he is talking about LMFAO. You and I rarely agree on anything too.

Low PRFs without doppler are good for detection and why that is why the F-22 is claimed detected by all these countries like Venezuela and Russia lol. They are using low PRFs. However, High PRFs are required for targeting! The F22 is not hard to detect, it’s hard to track and generate a competent fire solution. It is not true stealth like the B-2 or B-21.That is why even the most advanced radar missiles AA & SA are all High PRF (interrupted continuous wave) ONLY and it is required to guide to impact. Even the R27ER must be supported by High PRF in the terminal and cannot do so alone on inertial guidance and IRST.

Because systems using PRF above 30 kHz function better for targeting because direct velocity can be measured up to 4.5 km/s but range resolution becomes more difficult by itself.

High PRF is limited to systems that require close-in performance. like radar missiles and air intercept radars. Not"head on mode The dumbest made-up terminology ever. As long as you are closing in on the target. It does not matter if are in a chase and they are flying away.

Continuous wave has **no minimum or maximum range, although the broadcast power level imposes a practical limit on range. The AWG9 should have the furthest range of all fighters when it locks a target at all aspects with the strongest field strength/broadcasting power Continuous-wave radar maximize total power on a target because the transmitter is broadcasting continuously.

When you lock a target, the radars are switching to a ** high pulse-repetition frequency**, or… aka High PRF.
The higher the PRF that is used, then the more the target is painted

The drawback of Systems using PRF above 30 kHz (High PRF) is that it becomes increasingly difficult to take multiple samples (radar return) between transmit pulses at these pulse frequencies, so range measurements are limited to short distances longer range targeting requires radars capable of emitting a combination differing PRF simultaneously to target at long ranges and having the digital processing power to interpret that and guide the missile.

Low PRF radars are the ones that have reduced sensitivity in the presence of low-velocity clutter that interfere with aircraft detection near terrain.

A radar system determines range through the time delay between pulse transmission and reception. For accurate range determination, especially over great distances a pulse must be transmitted and reflected before the next pulse is transmitted. The F14A is using low PRF to detect targets. Not while it is tracking. TWS is using a combination of both (because the jet is special like that) You cannot measure distance if you are blasting High PRF alone at targets beyond the horizon.

GJ and so many in the community have misunderstood and believed the opposite not attempting to ascertain for themselves.

[EL337GH0ST]

I’d like to see an 11 km frontal lock in-game at ~3 km altitude.

[Ziggy1989]

As much as we argue. I always do admire your enthusiasm for the game’s future and the intentions of the corporate leadership at GJ.

[AlvisWisla]

Go into a custom battle on an EC map and lock one of the F-104/Su-7s.
I even did this against a Mig-29 friend of mine when we were goofing off.

[MiG_23M]

You have shown a complete lack of understanding for how radar missiles function under various pulse repetition frequency. I think to put it simply and help you do your own (better) research… the AMRAAM (the primary discussion topic of this particular thread) goes “Pitbull” in a medium pulse repetition frequency range. This is for a reason.

Also, it seems you’re implying that SARH missiles go Pitbull here? You’re aware that the radar on the launch aircraft has to keep the target illuminated until missile impacts / detonates right? If the F-15 does so in a high PRF mode it will be limited mostly to head-on scenarios… and as far as I’m aware only early pulse doppler radars require a HPRF “lock” to get a “weapons grade track” on target. The older transmitter (CWI) was necessary and on newer aircraft they went away with this simply because the receiver of the Sparrow switched to monopulse or because the missile had it’s own active seeker and only needed mid-course inertial commands transmitted through sidelobes…

The F-14 retained a CWI, the F-15 did not. There was a study that showed how the F-15 could guide the AIM-7 via it’s high PRF radar mode without a continuous wave illumination device. This limits you to firing the Sparrow and guiding it almost solely with the “head-on” mode (High PRF) in War Thunder. That is the issue we are facing, and while I’m not up to date on my reading of the F-16C’s radar, if it lacks a continuous wave illumination device it would have a similar issue iirc.

This is how they are modeled in war thunder… yes… however it is somewhat realistic and based on reality. I suggest you do some more research into why "Continuous wave interrupted’ (High PRF 30+khz) is not normally used outside of closer ranges by stuff such as proximity fuse sensors.