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

Lofting parameters in-game are rudimentary as I stated.

@MaMoran20 Time to target for the 39km test in those parameters was approximately 60s with the adjusted missile.

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fine tuning, the Rtr and the 9.6NM case would make as close as possible atm. Just lofting and guidance now. And defining how many Gs in the turn for Rtr case, will check if I can see anything tomorrow.

Thanks

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Well, we know the maximum launch range for subsonic launch aircraft (0.96 mach launch) against unknown target speed (presumably co-speed, or 0.9 mach) and co-altitude for max height of Sea Harrier was around 40 nautical miles. This lines up with my testing, showing a maximum range of around 75km in that scenario. (Hits at 75km in ~75-80s iirc).

Overall, it seems my custom missile file is close to the ballpark performance metrics of the real thing with the public data. Interested to see how it comes to the game.

I’m honestly quite surprised loft in-game isn’t modelled in a similar manner as time to gain for long range SARH’s. Seems extremely rudimentary and quite lazy tbh.

Regarding what would be an ideal loft, I think its more dependent on the range to target relative to the current max kinetic range of the missile, granted that’s just a logical guess rather than backed up by documentation.

For example, a very high loft trajectory may maximize kinetic energy at intercept, but would increase the time to target as well, giving the target more time to maneuver and avoid the missile. This would likely be optimal when the target is already close to the max aerodynamic range, where noticing the TWS launch is less likely, and what’s more important is maximizing energy at range.

A closer launch may loft less and take a much more direct route as the range would be insufficient to really gain good altitude anyways, and the target is much more of a threat to the launch aircraft.

There’s likely a set of guidance rules and sets of equations to determine optimal loft for each individual missile as well irl. A higher drag missile will likely favor lofting more aggressively to reduce drag, so will a long burn motor missile, as not only does drag decrease with altitude (due to decreased air density), but thrust of rocket motors INCREASE with altitude, and the %increase is proportional to the length of the motor burn as well.
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This would explain why irl, the AIM-54 has been known to loft to altitudes as high as 103500ft to intercept a target flying at 50000ft from a 44000ft launch.
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I dont think WT actually models differential rocket motor thrust based on altitudes, and we know for a fact they dont model base drag reduction from long burn motors either, so its questionnable as to if any missile which lofts ingame actually acheives realistic loft trajectories or peak performance.

That actually leads into a major concern I have in the near future with gaijin and their missile modeling; around what parameter will they base their missile modelling in the future when missiles become more varied and sophisticated?

The AIM-54 lofts aggressively to achieve huge ranges and speeds by leveraging low air density and its large and long burning motor, both of which benefit the increase in rocket motor thrust at higher alts.

The R-77 may achieve good ranges from high speed launches, but suffers massively from its grid fin design at subsonic/transonic launches, which would lead to it underperforming in typical WT scenarios.

The MBDA meteor lofts very little so as to maximize thrust from its ramjet engines, and varies said thrust to mitigate the effects of the targets evasive actions and maximize pK.

Those are just 3 examples, but are applicable to a whole host of future medium and long range BVRAAM’s for WT. I seriously believe the complexity of the missile models will have to be increased to be realistic, although I personally believe gaijin will take the easy way out and model things in a way in which there are clear winners and losers.

A great example of this “winners and losers” modelling are long motor burn missiles in WT. Missile diamonds appear within 10km range (aced crew) for missiles where the motor is still burning, so shorter burn missiles have a massive advantage in visibility, which improves their pK. This even has ramifications for low smoke motors like the AIM-9M, which should have a visibility advantage over something like the P3, but comes out with a disadvantage due to the longer motor burn and missile diamond.

It will likely be near impossible to model a more modern missile accurately in WT within the confines of gaijins current missile modeling. You may be able to fine tune for one specific scenario, but it by no means means that the missile would be accurate for all scenarios, or even the scenarios most commonly seen in WT matches (low alt low speed launches).

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For most missiles in-game (no more or less different than other missiles with boost or boost-sustain type solid rocket motors)… the discrepancy in performance from low and high altitude or close and medium range time to target it’s within 5-10% margin of error. Not a huge deal.

For missiles that loft, the lofting parameters are not explicitly stated so as long as it hits targets at prescribed ranges and speeds it should likely be performing as accurately as we need it to be.

I don’t really see the issue with how it’s being modeled currently, but I would welcome improvements over time.

tbh, I doubt the F-14 was ever meant to come out as early as it did. They just rushed it and more advanced missiles for the Top Gun promo. It would explain the deficiencies in it’s modeling and the fairly massive power creep with its introduction.

I suppose we’ll have to see how the meta plays out, but considering the pretty significant time-to-target shifts from the lofting profile, I don’t see how they could hope to accurately model any of the lofting missiles without more advanced stuff.

Something like the Phoenix would be modeled for its 72.5NM max range, but to get that they’d have to either juice the snot out of the lofting profile or total delta V to beat the battery life.

If it lofts too aggressively it’ll have a dramatically longer time-to-target in medium range shots than it should. If it isn’t aggressive enough they’ll have to juice the thrust/delta V to get it to travel its maximum range in its battery life.

Also, it shouldn’t be that hard to implement, since like @MythicPi said, it should be a simple conversion of distance to angle. Recreate known shots with whatever formula and we’ll end up close enough.

When was that stated as the max range?

I think the way you described this, you may not understand how the lofting mechanism is done in-game.

That’s what they’ve done?

The F-14A wasnt powercreep at its introduction. It frankly baffles me ppl get that whole part of WT history so badly wrong.

The F-14A at launch was added at a time when the MiG-23MLD and J-7E had utterly ruined top tier air for months. The MLD in particular had been absolutely crushing all balance in air RB for about 8 months when the F-14A was added, and the J-7E had gotten the PL-5B “fix” which made it borderline god tier when matched to its FM, the F-14A was added as a balancing factors to those 2 nightmares.

As for its timing, I agree it was added to match Top Gun Maverick, but I disagree it was rushed. TGM was famously delayed MULTIPLE times. One of the specific dates was November 19th 2021.
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This date is important as it roughly coincides with the release of the MiG-23MLD (Oct 28th), which went on to absolutely dominate top tier for 8 months with literally no answer from the US side until the F-14A. The F-14A was most likely supposed to be released alongside the MLD, but was delayed alongside TGM.

Regarding the F-14B though. It being added was just beyond stupid. Gaijins stated reason was the US needed a competant mixed attacker, but they;

  • Refused to add any of the 3 TGP’s and dozens of different PGM’s to the F-4E
  • Refused to add the F-111
  • Refused to add a TT A-6E

The addition of the F-14B was lazy and idiotic. There was no reason to add it when they did, and they butchered the modelling of not only its weapons (the 7M is still nerfed into the ground as is the 54C) but the AN/AXX-1 TCS. Adding the F-14B (a notoriously poor aircraft in the ground attack role) for the role of TGP equipped ground attacker was just stupid, and the US TT could’ve gotten half a dozen different aircrafts instead.

As for if you’re arguing the 54C is nerfed into the ground for balance, the 54C is one of the worst missiles, if not flat out the worst missile you’ll find at top tier, and the R-27ER, which has been downright oppressive since its addition compared to all other radar missiles in-game, handedly beats it in almost all scenarios you’d see in WT currently.

This is also kind of wildly off topic for an AIM-120 discussion…

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Yeah I don’t really, idk if its X degrees relative to missile or relative to target

Spoiler

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Target = 990 mph, 50k feet
Missile travels 72.5nm
Target travels 37.5nm
72.5+37.5 = launch range of 110nm
Since its a target drone I assume it maintains course and speed

Target drone covers 43.15 standard miles from launch to impact, traveling at 990mph (.275 miles per second). That gives a time of (43.15 miles / .275 miles per second) 156.9 seconds from launch to impact. Assuming I didn’t fuck my math, that’s almost the missile’s known battery life of 160s, thus likely pretty close to the maximum range (Since it’s the longest range shot known to have been taken)

That was a random engagement, not theoretical max range as far as I am aware. The AIM-54 should be able to hit fighter sized targets from 100 nautical miles launch distance in similar or higher launch speed scenarios.

I believe it climbs at “X” angle until the seeker is tracking target with “Y” angle elevation at which point it maintains that degree until it comes in to intercept if I understand it correctly. It’s kind of rudimentary as I stated, but it isn’t terrible and serves the purpose quite well in-game.

Ah, it was the missile’s distance traveled, not the launch range. Launch range was 110nm as shown there

And even that is not stated as the maximum range, something to note.

The current AIM-54 seen in-game has downright atrocious dV’s btw. Barely eaks above M4.0 from a M2.0 launch at 12000m attitude with the whole motor burn, and down at 6000m M1.0 launch its barely reaches above M2.0 or 3.0 iirc.

From this test.
dV in the M2.0 12000m case was ~716m/s
dV in the M1.0 9000m launch was ~611m/s

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True, its definitely not perfect but that’s the most aggressive known loft, and its pretty ideal conditions (High altitude mach 1.5 launching and target craft) The only way to really know is from docs or a full-on fluid simulation but I don’t have those resources.

It could probably go maybe 10nm further than that under truly ideal conditions, but again no docs so we can’t prove it. Also everything I’ve seen states its battery life is >160 seconds so who knows it might be way better than even that.

Is there a condition where it hits mach 5? I’ve always been under the impression that the ‘max mach’ stat was just for stat card but that testing seems to imply otherwise.

Edit: off topic

Should be capable of mach 3 at sea level in terms of top speed, and mach 6.1 at higher altitudes.

In fact, the performance of the motor is almost as it should be (correct thrust)… but it does not add the additional ~15% thrust Gaijin should add to simulate the reduction in drag during missile burn time. Further, the drag on the missile is too high because it’s incapable of reaching the top speeds it should reach at low and medium altitudes let alone at high alts.

In-game it has ~96,700 lb-sec, should be a bit closer to 99,000 lb-sec.

Should be mach 6.1

We can probably move this to the AIM-54 thread though lol…

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I’ve never heard of those terms in my life, only “maximum assured range” and “minimum engagement range”

@MaMoran20 I wonder if the AIM-120 follows such a guidance law that would allow it to take advantage of certain phenomena like this; ??

The in-game model was flying straight towards the lower alt target with no loft… would act as the red line.

It’s possible that it can follow one of these curves instead. This would explain the discrepancy in time to target in that specific scenario.

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