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Active radar missiles lock losing conditions


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Hi,

 

       As far as the latest update tells, the AIM-120s (both B and C probably) have their target tracking loss conditions based on various factors, as stated:

"AIM-120. Chaff bug - changed chaff/slow moving targets filtering logic, introduced ground clutter model, missile notching now depends on target/clutter signals ratio, range of blind velocities depends on geometry of intersection of seeker beam and ground."

 

I'm very excited about this new tracking model as it looks (at least for me) to make more sense, compared to reality, that in some given conditions, both the pulse (be it HPRF (high pulse repetition frequency) or MPRF (medium pulse repetition freq.)) and the doppler (due to relative closure velocities vs. beam angles vs ground) modes are unable to maintain a lock anymore!

Now, I don't know what was it all about the "chaff bug", because after hundreds of tests (done dozens just today), the AIM-120s (B&C) won't go for chaff whatever magic you might try. Only the R-77 still goes for chaff and quite easily I'd say as just some 3-5 chaff thrown in 0.02 seconds (from F-16) can have the R-77 go for them for good when beaming at the same time. I tried high speed 90+ degrees descending turns and beaming from an initial head on incoming AIM-120B or C while throwing chaff as fast as my finger could press the chaff button and the missile would never ever go for a single chaff until it hits my plane. I tried the same at low speeds and very low speeds (below 200km/h) and still, the missile will never go for chaff. Yes, at very low speeds while beaming it will go for the ground, but never ever for chaff anyway.

So these are my 2 questions, if I may:

1. In which conditions would now (based on the latest update) the AIM-120s go for chaff, if will it ever go?

2. What would be the blind "+/-" closure speeds for the new model or relative ground projected speeds of going away or closing in towards the missile, condition for which the missile's doppler can't distinguish between ground and aerial target?

 

As far as the DCS F-14's radar (big-powerful radar) capabilities manual tells, there is a +/- 100knots that the target should have compared to the own aircraft's ground speed, below which the target is lost. So it only tells about the relative +/- closure rate of the target relative to the targeting radar and the ground, NOT about how fast the target is actually flying perpendicular to the tracking radar. So I would understand from the following statement, that I can have even Mach 2 and if the missile is looking towards the ground at my plane, as long as it's not closing or going away from the tracking radar with more than +/- 100 knots, it would still be invisible. Is that true? This is what it tells:

 

"This blind area is a hardware limitation as it is a doppler radar mode it cannot detect targets without a doppler
shift. The resulting blind area is 200 knots wide, meaning that a chased target moving at a speed of within 100 knots
(+/-) of own groundspeed will be invisible to the radar. This means that when chasing a fleeing target it may very well
be necessary to use the pulse modes instead."

Yes, fighter and missiles own radars have been brought to be more performant, but by how much, that's the question? Let's not first forget that a missile's radar is still very small compared to that of the fighter which launched it, so I believe that it should have greater overall limitations on keeping a target tracked compared to a fighter's radar. I might be all wrong and the missile's radar is more capable than that of a fighter, but logically, it should be the opposite!

Flying has always been a great interest for mankind, yet learning everything about it brought the greatest challenge!

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Posted (edited)

Umm.... the 120C loves chaff as normal this update. IDK what your testing is composed of, but its still insanely easy to notch/chaff. What changed is that it no longer pulls 40G turns to track on stationary chaff outside the FoV, so it did end the notch immediate recommit meta. You need to stay in the notch until impact. But notching with or without chaff is quite effective rn.


Edited by dundun92

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U did all the test on SP right?

I've witnessed 120 may have different notching / chaff eating behavior between SP and MP, not sure if there is a desync bug here.

Deka Ironwork Tester Team

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On 5/29/2021 at 12:09 AM, dundun92 said:

Umm.... the 120C loves chaff as normal this update. IDK what your testing is composed of, but its still insanely easy to notch/chaff. What changed is that it no longer pulls 40G turns to track on stationary chaff outside the FoV, so it did end the notch immediate recommit meta. You need to stay in the notch until impact. But notching with or without chaff is quite effective rn.

 

Hi, thx for the reply! I've found out that only if I fly as slow as 110-120kts ground speed (~200km/h GS) close to the ground (usually below 100ft AGL) and maintain about 80..100 degrees from the incoming missile's path, I never need to use one chaff and more than 90-95% of the missiles will lock onto the ground somewhere. Some 5-10% still get a chance to remain locked on the plane, by some logic! But..., I tried beam notching the AIM-120C while coming from head on both at high speeds and low speeds and never ever it went to chaff even if I spoofed 20 chaff a second, unless the speed dropped below a threshold and depending on the rate of change of my velocity vector (this seems to make the radar falsely predict where I should be in the next moment) it will eventually lose lock, but the chaff does nothing! I'll provide a track of what I did and it won't go for chaff and I'd be happy to see how you made it go for chaff. From what I can see, the lock breaking of the AIM-120C is not due to chaff, but only due to the low&slow 1st notch combination. The B model, on the other hand, does go for chaff, although with a much lower chance than an R-77 (for example, not as if it should be related to it or anything like that).

 

aim-120C vs beam notch vs chaff.trk Aim-120C vs beam notch vs chaff.acmi

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Chaff isnt supposed to do much outside the notch. Its pretty easily filtered out. Whats unrealistic is all the other missiels going after chaff when well outside the notch

Eagle Enthusiast, Fresco Fan. Patiently waiting for the F-15E. Clicky F-15C when?

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Posted (edited)
On 6/2/2021 at 6:25 PM, foxwxl said:

U did all the test on SP right?

I've witnessed 120 may have different notching / chaff eating behavior between SP and MP, not sure if there is a desync bug here.

Hehe..., welcome! Yes, I was in SP this time! This MP only issue is for years now. It's most probably due to lagg/sync as you mention. I can't even count how many times I've been doing guns only fights and I could clearly see the attacker's bullets go way by me and at the same time I get damaged and after I check the Tacview, it also proves that no bullet has ever hit me and the white flashing box never appears, but in-game it simulates as if I was hit. The exact opposite thing I did to another player as I've shot bullets with the Su-27 (they are like a line of bullets, little spread) at him and the bullets clearly missed him by tens of meters and all of a sudden I see him flaming, then after he ejects it said that I've hit him with 30mm, and again..., the Tacview shows that NOT a single shot has ever hit him. LOL! Think of that when you wanna go GUNZO on someone else spraying bullets allover the place. You clearly have all the bullets on him and they all miss, but if you clearly miss, it sometimes hits him and vice-versa on you!

6 minutes ago, dundun92 said:

Chaff isnt supposed to do much outside the notch. Its pretty easily filtered out. Whats unrealistic is all the other missiels going after chaff when well outside the notch

Aka R-77 and other?


Edited by 85th_Maverick

Flying has always been a great interest for mankind, yet learning everything about it brought the greatest challenge!

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1 minute ago, 85th_Maverick said:

Aka R-77 and other?

yes

Eagle Enthusiast, Fresco Fan. Patiently waiting for the F-15E. Clicky F-15C when?

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On 5/29/2021 at 12:09 AM, dundun92 said:

Umm.... the 120C loves chaff as normal this update. IDK what your testing is composed of, but its still insanely easy to notch/chaff. What changed is that it no longer pulls 40G turns to track on stationary chaff outside the FoV, so it did end the notch immediate recommit meta. You need to stay in the notch until impact. But notching with or without chaff is quite effective rn.

 

So I come back with the asking! Can you provide us tracks/recordings of 120C's loving chaff? I've just provided you with what I've found, which is that in more than 90% of cases you'll always be missed by all active radar missiles (120s, 77s, etc.) when flying low/slow and beaming without a single chaff dropped, while the chaff never makes any difference. Cheers!

Flying has always been a great interest for mankind, yet learning everything about it brought the greatest challenge!

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So, silently you agree with me that the AIM-120C never goes for any chaff, but it's rather nicely modeled for the pulse-doppler radar modes limitations on losing a target in 1st notch conditions. Not insanely easy at all to evade by notching, but at least it simulates something about it, the chaff, is 100% useless on the C model.

Flying has always been a great interest for mankind, yet learning everything about it brought the greatest challenge!

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Posted (edited)
1 hour ago, 85th_Maverick said:

So, silently you agree with me that the AIM-120C never goes for any chaff, but it's rather nicely modeled for the pulse-doppler radar modes limitations on losing a target in 1st notch conditions. Not insanely easy at all to evade by notching, but at least it simulates something about it, the chaff, is 100% useless on the C model.

No, I intended to respond but have been quite busy, TBH theres not much point making tracks for this. Ive notched and chaffed enough 120s to know it has effects on both the B and C. The fact that the missile isnt making a 40G turn towards the chaff (which was unrealistic, and fixed) doesnt mean it has no effect. Chaff increases the odds of the missile breaking lock and not reacquiring.


Edited by dundun92

Eagle Enthusiast, Fresco Fan. Patiently waiting for the F-15E. Clicky F-15C when?

HP Z400 Workstation

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The Alamo Squadron is looking for dedicated Air-to-Air focused pilots

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