reported AIM-120C losing targets easily for chaff even at close ranges

[Comrade Doge]

Hello, it looks like the AIM-120C is in a pretty sorry state right now regarding maintaining tracking of a target, missiles fired from ranges of 10-13 miles lose the track of the target at ranges closer than 2 miles from impact, even half a mile in cases. All you have to do is use chaff, not much, one puff is enough to trick any AMRAAM, even at half a mile distance from impact. I am attaching trackfiles, tacviews, and links of short videos below. You can see the issue is replicable with your own plane, or with AI. I hope this will get fixed soon, as the missile has reached impossible levels of unusability.

 

3 videos from 3 of the tacviews:

AMRAAM miss 5 

AMRAAM miss 4

AMRAAM miss 3

AMRAAMmiss1.trk AMRAAMmiss2.trk AMRAAMmiss3.trk AMRAAMmiss4.trk AMRAAMmiss5.trk AMRAAMmiss2.acmi AMRAAMmiss3.acmi AMRAAMmiss4.acmi AMRAAMmiss5.acmi AMRAAMmiss1.acmi

[BIGNEWY]

Thanks for the tracks and the DM's in discord. We will check it out. 

[Maddog 1]

I have not seen this problem the other day I was in the Viper and used 120B in dogfight mode with out alock went pitbull and found the target

 

[Rich]

I would also recommend doing some testing with real players as criteria for decoying changes depending on if it's AI or an actual player that's doing the launching or defending.

[BIGNEWY]

I have shown the team the tracks, and it looks correct in this circumstance. 

 

The missile can lose the target due to 3-9 condition and chaff, in addition due to short range target it quickly goes out from seeker FOV. 

 

Thank you

[creme_fraiche]

@BIGNEWYCan you confirm that this effect is a result of the missile looking down at the target, which might cause the target to get lost in the ground clutter (notch)?

 

The effect does seem less pronounced when firing from low to high, which makes me think its being caused by a notch (high to low shots). Here are a couple low-to-high tracks:

fox3_test_3_30k_2.trkfox3_test_3_30k.trk

 

Corresponding tacviews:

Tacview-20210202-115344-DCS-fox3_test_low_hi.zip.acmiTacview-20210202-115726-DCS.zip_low_hi.acmi

 

I did see 1/6 missiles dive for chaff while looking up at a target, but anecdotally, when the missile is looking down there seems to be a very high chance (greater than 50%?). Given that AAMRAMs loft, this will mean that a high percentage of missile shots will be looking down.

 

I understand that a bigger sample size would be needed to determine anything empirically.

 

Any additional insight would be greatly appreciated.

Edited February 2, 2021 by creme_fraiche

[BIGNEWY]

thanks we will take a look, and run it passed the team in the morning. 

 

Edit: I'm not an expert with missiles by any means, but I dont see a problem in these tracks. Looks good. 

[creme_fraiche]

 

20 minutes ago, BIGNEWY said:

thanks we will take a look, and run it passed the team in the morning. 

 

Edit: I'm not an expert with missiles by any means, but I dont see a problem in these tracks. Looks good. 

I was just posting some low-to-high shots, which seem to have a higher Pk than the inverse. I'm just looking for confirmation around notching.

[captain_dalan]

On 2/2/2021 at 10:34 AM, BIGNEWY said:

I have shown the team the tracks, and it looks correct in this circumstance. 

 

The missile can lose the target due to 3-9 condition and chaff, in addition due to short range target it quickly goes out from seeker FOV. 

 

Thank you

What is the FOV angle for the AIM-120C? And is it the same for all actives? (120B, 54A, 54C, R-77....)

[Cmptohocah]

3 hours ago, captain_dalan said:

What is the FOV angle for the AIM-120C? And is it the same for all actives? (120B, 54A, 54C, R-77....)

I think it's 7 or 13 deg.

[GGTharos]

On 2/3/2021 at 5:49 AM, captain_dalan said:

What is the FOV angle for the AIM-120C? And is it the same for all actives? (120B, 54A, 54C, R-77....)

 

6 degrees for most RF guided AAMs.  Yes, chaff will be out of FoV before it can be effective realistically inside certain ranges, but at the same time that's not how chaff in DCS has ever worked.   ED has a bunch of considerations built into the chaff rejection algorithm, perhaps they should add distance to target to the look down, aspect and # of decoys in FoV considerations.

[DCS FIGHTER PILOT]

On 2/2/2021 at 3:35 PM, BIGNEWY said:

thanks we will take a look, and run it passed the team in the morning. 

 

Edit: I'm not an expert with missiles by any means, but I dont see a problem in these tracks. Looks good. 

 According to other posts that I have seen, the AMRAAM should not just go berserk and go for chaff if it looses a target that is notching. Right now, an AMRAAM going for chaff is much like a heater going for flares. I’m pretty sure this is not how it should work. An AMRAAM, like most modern ARH missiles, have advanced anti chaff algorithms that I am sure would prohibit the kind of bizarre behavior we are seeing. For example, at close range when the DCS AMRAAM gets spoofed by chaff, the position of the chaff that is thought to be the aircraft by the missile, could never actually be the aircraft due to the simple fact that basic physics and aerodynamics would never allow that aircraft to radically change its position in such a way in such a small time frame. I would highly suspect that real modern ARH missiles take this into account and maintain a relatively fixed course should they loose the target for any reason. The DCS AMRAAM on the other hand, clearly does not take this into account and will execute a maneuver putting it well over 20g’s to go for the chaff.

Edited February 6, 2021 by DCS FIGHTER PILOT

[nighthawk2174]

46 minutes ago, DCS FIGHTER PILOT said:

 According to other posts that I have seen, the AMRAAM should not just go berserk and go for chaff if it looses a target that is notching. Right now, an AMRAAM going for chaff is much like a heater going for flares. I’m pretty sure this is not how it should work. An AMRAAM, like most modern ARH missiles, have advanced anti chaff algorithms that I am sure would prohibit the kind of bizarre behavior we are seeing. For example, at close range when the DCS AMRAAM gets spoofed by chaff, the position of the chaff that is thought to be the aircraft by the missile, could never actually be the aircraft due to the simple fact that basic physics and aerodynamics would never allow that aircraft to radically change its position in such a way in such a small time frame. I would highly suspect that real modern ARH missiles take this into account and maintain a relatively fixed course should they loose the target for any reason. The DCS AMRAAM on the other hand, clearly does not take this into account and will execute a maneuver putting it well over 10g’s to go for the chaff.

 

+1 , its more than just this though, the amraam should be able to filter it out based on its Vgate, Range gate, filtering all returns outside the rescell, and its even possible to deteermine when there are multiple targets in the res cell and 'weight' the radar towards one or the other, and if its still getting datalink updates that should prevent it chasing false targets as well.

;

Don't quite feel like posting a full write up but my opinions and supporting dcs are here:

 

 

this is defintly an issue that needs to be fixed.

[Cmptohocah]

8 hours ago, DCS FIGHTER PILOT said:

...Right now, an AMRAAM going for chaff is much like a heater going for flares. I’m pretty sure this is not how it should work...

This is how all ARH/SARH missiles behave in DCS. Chaff does nothing to the launching radar also, and it should.

 

[DCS FIGHTER PILOT]

On 2/2/2021 at 4:34 AM, BIGNEWY said:

I have shown the team the tracks, and it looks correct in this circumstance. 

 

The missile can lose the target due to 3-9 condition and chaff, in addition due to short range target it quickly goes out from seeker FOV. 

 

Thank you

So I have just got done with some testing myself and this is what I found.

Note in tracks 2 and 3 it took ONLY ONE CHAFF PACKET to make the Aim-120c go stupid. On top of that, in the second track, the missile pulled OVER 30 G'S to go for a single chaff packet. I'm also pretty sure that, that chaff would have been out of the seekers FOV as well. In tracks 1 and 4, it took a whopping TWO chaff packets to decoy the 21st Century missile. I highly doubt any of this is correct and I urge you to show this to the team. 

Aim-120C Spoofed 1 trk.trk Aim-120C Spoofed 2 trk.trk Aim-120C Spoofed 3 trk.trk Aim-120C Spoofed 4 trk.trk

[Nealius]

I'm afraid tracks will not help much because the sim recalculates, and thus the "dice roll" chance of that one or two chaff packets will give a different result each time the track is replayed. Despite constant demand for replay tracks for debugging, they are entirely unsuited for debugging precisely because they recalculate everything instead of replaying exactly what happened. Ergo, the bug symptom may not appear at all simply because the replay system is junk.

[DCS FIGHTER PILOT]

31 minutes ago, Nealius said:

I'm afraid tracks will not help much because the sim recalculates, and thus the "dice roll" chance of that one or two chaff packets will give a different result each time the track is replayed. Despite constant demand for replay tracks for debugging, they are entirely unsuited for debugging precisely because they recalculate everything instead of replaying exactly what happened. Ergo, the bug symptom may not appear at all simply because the replay system is junk.

That’s the thing, this type of behavior is EASILY recreated and anyone can do it. I have lost literally dozens of kills to people who do this when instead, they should be nothing but fireballs. It’s frankly, maddening. I created these tracks to show what just ONE or TWO chaff packets can do, just think how bad it would be with more than that. 

Edited February 6, 2021 by DCS FIGHTER PILOT

[dundun92]

AT this point, you just pretty much have to accept that we are gonna be dealing with chaff-loving missiles for some time, at least until EW gets overhauled

[nighthawk2174]

5 hours ago, dundun92 said:

AT this point, you just pretty much have to accept that we are gonna be dealing with chaff-loving missiles for some time, at least until EW gets overhauled

Yeah I mean its been like this since the very start as well so I'm not expecting much progress either.

[Csgo GE oh yeah]

On the plus side, watching tacviews is quite hilarious right now. 

[Nealius]

A few months ago chaff resistance was more realistic until ED nerfed it into its current state, for reasons unknown. 

[DCS FIGHTER PILOT]

2 hours ago, Nealius said:

A few months ago chaff resistance was more realistic until ED nerfed it into its current state, for reasons unknown. 

I suspect it was for balancing. 

[GGTharos]

No, it was because some people complained that it was different from before.   Of course they continue to complain that R-27s are too sensitive at the same time.

[Fri13]

On 2/2/2021 at 11:34 AM, BIGNEWY said:

I have shown the team the tracks, and it looks correct in this circumstance. 

 

The missile can lose the target due to 3-9 condition and chaff, in addition due to short range target it quickly goes out from seeker FOV. 

 

Thank you

What is the AIM-120C seeker IFOV in the game?

Just asking for the future testing in various scenarios....

 

[BIGNEWY]

15 hours ago, DCS FIGHTER PILOT said:

So I have just got done with some testing myself and this is what I found.

Note in tracks 2 and 3 it took ONLY ONE CHAFF PACKET to make the Aim-120c go stupid. On top of that, in the second track, the missile pulled OVER 30 G'S to go for a single chaff packet. I'm also pretty sure that, that chaff would have been out of the seekers FOV as well. In tracks 1 and 4, it took a whopping TWO chaff packets to decoy the 21st Century missile. I highly doubt any of this is correct and I urge you to show this to the team. 

Aim-120C Spoofed 1 trk.trk 176.18 kB · 1 download Aim-120C Spoofed 2 trk.trk 164.25 kB · 1 download Aim-120C Spoofed 3 trk.trk 100.26 kB · 1 download Aim-120C Spoofed 4 trk.trk 161.53 kB · 1 download

 

I have made a report using your tracks for the team to check.

 

thank you