Aim 120 / Aim9x Performance against low flying Planes/Helos

[Wobbly]

i got a question. The Aim 120s and Aim 9Xs seem to be completly unable to hit someone if he is flying low enough. I expirienced this multiple times over the last few weeks, mostly against Helos but here i caught a nice Example of chasing a viggen on Video:

I launched a total of 6 Missiles on him, 4 120s and 2 Aim 9s. He succesfully evaded all of them by flying straight. Now i read in one of the patchnotes a while ago that "Ground clutter" is simulated. That would maybe explain the effect on the 120s. Even though i can#t imagine how at that launch angle and even ground the viggen could be hidden by ground clutter.

What confused me way more though, is the second Aim9 that i launched at 1:25. It is rear aspect at a viggen with full Afterburner. So really ideal launch parameters. It looks like at a certain altitude, maybe 150 feet, it just stops tracking and flys straigt.

After all this explanation. Is that intendet behavior? I can't imagine it to be. especially for the Aim9s
thx

[GGTharos]

Just now, Wobbly said:

After all this explanation. Is that intendet behavior? I can't imagine it to be. especially for the Aim9s
thx

It is both intended and incorrect.  AIM-120s are perfectly capable of scoring direct hits often against non-maneuvering cruise-missile targets flying at tree-top levels.

This clutter simulation should only apply to very old missiles, even AIM-7M didn't have this type of problem.   The miss distance should increase if the target maneuvers, then settle to something small quickly (the newer the missile the quicker, and very old missiles maybe never settle).

Instead the miss distance as implemented by ED is huge, does not take maneuvering into account like it ought to and appears to be set up to cause misses even at high altitude, just at a lower rate.  The simulation capability is going in the right direction but the effect is incorrect compared to IRL IMHO and according to a bunch of literature regarding seeker settling caused by scintillation which in the effect that I believe they're attempting to simulate here.

[Harker]

Pretty much what @GGTharossays. This behavior would be appropriate for significantly older missiles. It's the same story with chaff and notching. And the same behavior can be observed in look-down cases where the target is not close to the ground, just lower than the missile or aircraft. Indeed, they're going for correct-ish effects here, but they are massively overdone with respect to modern missiles. And they have apparently added an RNG-based aiming error mechanic, which further exacerbates the problem in other scenarios. Keep in mind that this implementation is likely WIP and probably pretty difficult to pull off correctly, so things will probably change in the future.

I invite you to take a look at these threads:
https://forums.eagle.ru/topic/285109-aim-120s-all-aim-120-api-missiles-in-277/
https://forums.eagle.ru/topic/283107-active-missile-look-down-notch-width-seems-excessive/
https://forums.eagle.ru/topic/287345-the-aim-120-in-278/
https://forums.eagle.ru/topic/290014-amraam-120c-when-fired-upwards-at-close-range-5-7-miles-targets-are-missing-randomly/

Edited January 5, 2022 by Harker

[Wobbly]

Thank you both for your Answers! Much appreciated
Then there is still remaing why the AIM9s do the same thing, they shouldn't be affected as they are IR. They don't need that simulated simply because this kind of tracking failure shouldn't exist on them .  Would love to see that removed from Heaters. Or is the tracking Algorithm the same with just some different parameters?

[GGTharos]

54 minutes ago, Wobbly said:

Then there is still remaing why the AIM9s do the same thing, they shouldn't be affected as they are IR. They don't need that simulated simply because this kind of tracking failure shouldn't exist on them .  Would love to see that removed from Heaters. Or is the tracking Algorithm the same with just some different parameters?

That is incorrect - IRH also suffers from scintillation and other effects, but again the newer the missiles the less it cares.  Arguably the 9X wouldn't care one bit.   Having said all this, both radar and IR missiles will suffer from things like background noise (different types, but still raises the noise floor), scintillation from the target maneuvering and the background (more for radar guided and older IR) and reflections from the ground/water, both in RF and IR wavelengths - as in a duplicate target image caused by IR reflection of the target's IR from the ground, same from RF, and/on in particular for RF, ground-bounce jammers.

Again, it's a complicated and difficult subject.  ED has made huge progress and brought a lot of good things, but unfortunately for whatever reason they chose not to model certain nuances of the things the did implement, which has a huge impact as you can see here.

[SCPanda]

Yeah, Aim-120C in the newest OB is not right. Too many misses and too easy to notch. Yesterday I fired my missile at the lead ship and the missile decided to track the trailing ship. I wonder if ED is working on improving the Aim-120s? Or they just think it's correct as is?