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

[Coxy_99]

Is this tested in MP? Checked the ACMI looks A.I sorry to say ive tested this over an hour in MP chaff train and notch same range and it tracks no issue so what gives?

Edited February 15, 2021 by Coxy_99

[Csgo GE oh yeah]

2 hours ago, dundun92 said:

Its the AIM-54 desync issue. If you looked at that clients replay youll find that it guided normally.

Really ?! 
Oh that is very problematic , this means that missile is nowhere near where i think it is when looking at my RWR ?
Could that also be why longer range shots are deemed more effective by some , because people are just notching the missile wrong because desync ? 
One more question though, this tacview is from the servers point of view. It's downloaded, does that matter any in terms of client/perspective ? I would guess so 

(it's multiplayer @coxy)

Edited February 15, 2021 by Csgo GE oh yeah

[GGTharos]

Yep, if you're not shooter you're simulating the shot, so there desync is a possibility for any missile.

[dundun92]

2 hours ago, Csgo GE oh yeah said:

Oh that is very problematic , this means that missile is nowhere near where i think it is when looking at my RWR ?

correct. Its laregly been fixed for the other AAMs, but (presumably) the intricacies of the AIM-54s guidance API are causing desync issues, which have been reported BTW and are being worked on.

 

2 hours ago, Csgo GE oh yeah said:

Could that also be why longer range shots are deemed more effective by some , because people are just notching the missile wrong because desync ?

doubt its the primary reason, most people have no clue how to properly notch a non desynced missile, let along a desynced one.

 

2 hours ago, Csgo GE oh yeah said:

One more question though, this tacview is from the servers point of view. It's downloaded, does that matter any in terms of client/perspective ? I would guess so 

Anything thats not shooter perspective has potential for desync. I do know that often client side (other than the shooter) can itself be desynced from the server, and both are often desynced from the shooter. DCS netcode really is a mess.

Edited February 15, 2021 by dundun92

[falconzx]

On 2/10/2021 at 7:49 PM, dundun92 said:

They dont in DCS

 

Nope, its super easy to chaff AMRAAMs in MP:

 

Do not SAY things you don't know, it's possible that someone here in the forums is going to actually trust your free words.

Here a video i Just did 10 mins ago to demonstrate what i say. Just make your own tests if you don't believe it, and look at tacviews.
 

 

[dundun92]

10 minutes ago, falconzx said:

and look at tacviews.

Would you mind linking any? And can you confirm that this has any effect on its actual effectiveness (which is the point in question)?

EDIT, by the above I mean, as far as im awarw DCS doesnt care about how fast the chaff is moving, it simply rolls a dice for the chaff it sees in the FoV, the only factors it takes into account as far as im aware are aspect, lookup/down, the number of chaff in the FoV, and the ccm_k0.

Edited February 16, 2021 by dundun92

[GGTharos]

Even if they move in the wind, in DCS it's irrelevant because that isn't being taken into account, at least not yet.

[falconzx]

Exactly, "aspect" in closure speed mean, it's the vector you are moving and not where your nose is pointing, and as you said it's considered, so if you are drifting, your aspect is not what you think it is. So as i said, posting random server tacviews without paying attention to the environment variables it's a mistake.
 Even if not so relevant, "the number of chaff in the FoV" is another factor influenced by weather conditions, btw, expecially at close ranges. Something moving with your plane is in the fov more than something flying away your plane.

[GGTharos]

1 hour ago, falconzx said:

Exactly, "aspect" in closure speed mean, it's the vector you are moving and not where your nose is pointing, and as you said it's considered, so if you are drifting, your aspect is not what you think it is. So as i said, posting random server tacviews without paying attention to the environment variables it's a mistake.
 Even if not so relevant, "the number of chaff in the FoV" is another factor influenced by weather conditions, btw, expecially at close ranges. Something moving with your plane is in the fov more than something flying away your plane.

 

Your closure if exactly what's relevant, and tacview does reveal this if you use the right switch.    At close ranges those chaff bundles aren't going to move enough ... I mean sure, the math literally changes wrt how many might end up in the FoV but I doubt you can expect the result to be anything but academic.   If you think it's a big factor, I'd be interested to understand the why.

[nighthawk2174]

6 hours ago, GGTharos said:

Even if they move in the wind, in DCS it's irrelevant because that isn't being taken into account, at least not yet.

I mean even then it would have to be moving quite quickly (really only possible at very high altitudes), plus i'd imagine its still possible to range gate or Vgate out the chaff.

[Teknetinium]

18 hours ago, falconzx said:

Do not SAY things you don't know, it's possible that someone here in the forums is going to actually trust your free words.

Here a video i Just did 10 mins ago to demonstrate what i say. Just make your own tests if you don't believe it, and look at tacviews.
 

 

I dont see AIM-120C miss more then it should in this track, there are some strange behaviours but it is related to your aircrafts gimble on the target. AIM-120 should as well be effected by jammers witch it is not modelled at all. I dont know where some got it from that AIM-120 could not be notched with chaff, jammers or effected by ground clutter. Actually the AIM-120 track surprisingly good in EDs world when being notched, chaffed, jammed against ground clutter. 

 

Tacview-20210210-235853-DCS-aim-120_TEST.zip.acmi

Edited February 17, 2021 by Teknetinium

[Noctrach]

@BIGNEWY Has there been any statement on this?

Chaff behaviour is bizarre for pretty much all missiles in the sim right now.

Targets nowhere near the notch (60-70 degree offset), looking up at targets against clear sky. Missile still gets decoyed.

I've seen missiles (both ARH and SARH) take 90 degree bat turns with over a mach of energy to spare, just to get to some chaff bundle almost a mile further back.

 

If you're half-decent at notching it's not even funny how easy it is to get rid of them, a split second notch with a broadside of chaff is all that's required.

It's not a matter of geometry, it's just about spamming enough of them. The 120C will do it a bit less than the 120B or the R-27, but it affects them all.

 

All this in singleplayer, I can work on providing tracks if needed.

Something is most certainly not right.

[SgtPappy]

On 3/12/2021 at 7:20 PM, Noctrach said:

@BIGNEWY Has there been any statement on this?

Chaff behaviour is bizarre for pretty much all missiles in the sim right now.

Targets nowhere near the notch (60-70 degree offset), looking up at targets against clear sky. Missile still gets decoyed.

I've seen missiles (both ARH and SARH) take 90 degree bat turns with over a mach of energy to spare, just to get to some chaff bundle almost a mile further back.

 

If you're half-decent at notching it's not even funny how easy it is to get rid of them, a split second notch with a broadside of chaff is all that's required.

It's not a matter of geometry, it's just about spamming enough of them. The 120C will do it a bit less than the 120B or the R-27, but it affects them all.

 

All this in singleplayer, I can work on providing tracks if needed.

Something is most certainly not right.

 

Not sure if it's widely understood yet, but chaff MP results will be a bit different from SP results. AI in SP will spoof missiles far more easily and their missiles will also be spoofed a bit more easily. A little weird, but this seems consistent when I tested spoofing AIM-54s, especially back when the chaff rejection of the AIM-54s was at AMRAAM levels.

[Noctrach]

1 hour ago, SgtPappy said:

 

Not sure if it's widely understood yet, but chaff MP results will be a bit different from SP results. AI in SP will spoof missiles far more easily and their missiles will also be spoofed a bit more easily. A little weird, but this seems consistent when I tested spoofing AIM-54s, especially back when the chaff rejection of the AIM-54s was at AMRAAM levels.

Multiplayer has a much lower tickrate than singleplayer. So the "diceroll" will be done less frequently, with the volume of chaff that AI spams this is a significant difference in the end result.

[dundun92]

3 hours ago, SgtPappy said:

Not sure if it's widely understood yet, but chaff MP results will be a bit different from SP results. AI in SP will spoof missiles far more easily and their missiles will also be spoofed a bit more easily. A little weird, but this seems consistent when I tested spoofing AIM-54s, especially back when the chaff rejection of the AIM-54s was at AMRAAM levels.

Yea its been like this forever. Back on even the old chaff model, I could notch missiles with a certain maneuver (in this case half Split-S to vertical notch + immediate recommit) + chaff deployment 100% of the time in SP; ran the same mission as a self hosted server and the manuever no longer worked even once

[BIGNEWY]

I dont have any news to share other than it has been reported to the team. 

 

As soon as I find something out I will pass it on. 

 

thanks

[BIGNEWY]

32 minutes ago, DCSoping said:

But @BIGNEWY  look  

 

 

 

 

 

F-14 Is deploying counter measures and doing an aggressive evasive manoeuvre, I dont see the issue. Missiles do miss, it isn't Hollywood

At the moment we are looking into the chaff issues, we are waiting for coupled INS and data link for AIM-120 to be completed. We will have to continue to be patient.

 

thanks

[nighthawk2174]

8 minutes ago, BIGNEWY said:

F-14 Is deploying counter measures and doing an aggressive evasive manoeuvre, I dont see the issue. Missiles do miss, it isn't Hollywood

The issue is their going for chaff when they should not be.  The chaff is causing the missile to pull maximum g's away from the target towards bundles that are already significant distances behind the target and would already have dropped well below the Doppler gate.  And if not the Doppler gate then the range gate (target in/near notch and missile opening gates as a countermeasure).  Not even mentioning the techniques that monopulses can employ to counteract chaff as well.  ED can easily give us a temporary solution by just returning the chaff resistance values back to what they were at when the new missile FM first dropped or just turning off chaff till its fixed.  Its just stupid how good it is and its having a really bad negative effect on gameplay and I would not mind it going away until its fixed and work properly.

[GGTharos]

3 hours ago, BIGNEWY said:

 

F-14 Is deploying counter measures and doing an aggressive evasive manoeuvre, I dont see the issue. Missiles do miss, it isn't Hollywood

At the moment we are looking into the chaff issues, we are waiting for coupled INS and data link for AIM-120 to be completed. We will have to continue to be patient.

 

thanks

 

Hi BIGNEWY, even in Vietnam, chaff was next to useless at any aspect other than nearly dead-on the 3-9.    There are graphs demonstrating this, but I don't know if I can find them any more.  If you weren't within literally 2 degrees of the 3-9 the doppler filter and edge tracking would defeat the chaff.    This may be very varied based on the system and other factors, but overall the effect of chaff is overdone - it needs an overhaul but, barring an overhaul, tightening up the aspect-based probability of decoying the missile would do just fine.  Leave it as-is on the 3-9 and reduce it to next-to-nothing everywhere else, since we can't do any better right now.

Edited March 19, 2021 by GGTharos

[TotenDead]

1 час назад, GGTharos сказал:

 

Hi BIGNEWY, even in Vietnam, chaff was next to useless at any aspect other than nearly dead-on the 3-9.    There are graphs demonstrating this, but I don't know if I can find them any more.  If you weren't within literally 2 degrees of the 3-9 the doppler filter and edge tracking would defeat the chaff.    This may be very varied based on the system and other factors, but overall the effect of chaff is overdone - it needs an overhaul but, barring an overhaul, tightening up the aspect-based probability of decoying the missile would do just fine.  Leave it as-is on the 3-9 and reduce it to next-to-nothing everywhere else, since we can't do any better right now.

 

Во вьетнаме у РЛС фантомов был допплеровский фильтр? 

[SgtPappy]

27 minutes ago, TotenDead said:

Во вьетнаме у РЛС фантомов был допплеровский фильтр? 

Only the F-4J radar system (AWG-10) had Doppler filter banks but I think GGTharos may be referring to SAMs which used edge tracking techniques.

 

I am not aware if radars in the F-14, F-15, F/A-18 etc. use this technique to reject chaff. I think the F-15 and F/A-18 for example have very good Doppler sensitivity since they had RAM mode which (AFAIK) uses fine Doppler shifts to discriminate close targets that would usually be too fine for the resolution cell.

Edited March 19, 2021 by SgtPappy

[GGTharos]

47 minutes ago, TotenDead said:

Did the phantom radar station have a Doppler filter in Vietnam? 

 

I don't know if it had a doppler filter the way we think of it today, but various radars (and especially sparrow) had a doppler tracking gate - so while there might not have been a filter in the sense that it 'deletes' things that today we'd think of as being in the notch, it still used the doppler gate along with angle and range gates to stay on target.

 

I really don't remember the details of the graph other than the curve itself and that it was 'probability of track disruption with chaff vs. aspect'.   The 'low' was 0.2 or less everywhere (so out of all missiles you launch, 20% or less would fail to track the target) and close to 100% would fail when the aspect was within 2-3 degrees of the 3-9 line - or well, the closer you got to it within those 2-3 degrees the closer it went to 100 - basically a spike.

 

I don't even recall which radar this concerned exactly.  You can imagine chaff will be far less effective with today's weapons, and the way chaff is represented in DCS certainly cannot simulate that graph right now, because in DCS we 'roll the dice' every time a chaff bundle appears where IRL this is simply not how it works.

Edited March 19, 2021 by GGTharos

[nighthawk2174]

@BIGNEWY @GGTharos

 

Couldn't find much more than this about chaff effectiveness but well its in the .01-.02% range for an older con-scan pulse tracking radar with MTI.  Considering stuff like the amraam is going to have much better resolution, is monopulse, will be closer meaning an even smaller res cell, and is PD.  And that based on other sources the bloom rate for the chaff in the simulation is highly optimistic well...  An additional factor to also consider is that the RCS of the target aircraft is 10, which is reasonable but for the off axis test the rcs of the aircraft was not varied where it would irl where it'd grow significantly as you approached the beam.  And even more so with an increase in look down or up angle on an aircraft.

Edited March 19, 2021 by nighthawk2174

[GGTharos]

Yup, while DCS doesn't simulate bloom it would be nice if it did.   0.2 seconds for RBC (Rapid Bloom Chaff) and more time for non-RBC.

[TotenDead]

5 часов назад, SgtPappy сказал:

Only the F-4J radar system (AWG-10) had Doppler filter banks but I think GGTharos may be referring to SAMs which used edge tracking techniques.

Если речь о РЛС ЗРК, что были во Вьетнаме, то они были не допплеровскими. СНР-75 имела опционально включаемый режим селекции движущихся целей, который работал по допплеру, но я не вижу смысла в его включении для уничтожения самолетов когда они не летят внутри превентивно рассыпаного облака фольги. Все диполи, что скидывал бы Фантом оставались бы позади него и не мешали бы его поражению. Важно отметить, что ракета С-75 - радиокомандная, так что она не может перенавестись на фольгу как более совершенные ракеты с полуактивным наведением

5 часов назад, SgtPappy сказал:

I am not aware if radars in the F-14, F-15, F/A-18 etc. use this technique to reject chaff. I think the F-15 and F/A-18 for example have very good Doppler sensitivity since they had RAM mode which (AFAIK) uses fine Doppler shifts to discriminate close targets that would usually be too fine for the resolution cell.

 

 

Касательно Ф-15/18 не могу сказать, а вот Ф-14 был однозначно плох для работы по целям на фоне земли. Даже в ближнем бою, судя по записям с ИЛС. 

 

5 часов назад, GGTharos сказал:

 

I don't know if it had a doppler filter the way we think of it today, but various radars (and especially sparrow) had a doppler tracking gate - so while there might not have been a filter in the sense that it 'deletes' things that today we'd think of as being in the notch, it still used the doppler gate along with angle and range gates to stay on target.

 

Допустим. Однако разве у Фантома были цели, которые могли бы сбрасывать дипольные отражатели?

 

5 часов назад, GGTharos сказал:

I don't even recall which radar this concerned exactly.  You can imagine chaff will be far less effective with today's weapons, and the way chaff is represented in DCS certainly cannot simulate that graph right now, because in DCS we 'roll the dice' every time a chaff bundle appears where IRL this is simply not how it works.

 

Да, конечно, нельзя отрицать того, что в ДКС ракеты и радары настроены далеко не идеально