AIM-120 does not always acquire flanking target with supported midcourse

[Default774]

The AIM-120 does not consistently acquire a flanking target on active, even when the missile is fully supported through the entire midcourse stage. The missile never acquires the target even though it is being provided datalink updates from the parent aircraft.

120_naq.trk 120_naq2.trk 120_naq.acmi 120_naq2.acmi

Edited November 26, 2022 by Minimalist

[Mike_Romeo]

Looks to me like the missile was notched. Missiles are using a doppler radar that detects targets by speed difference against the ground. So they only can detect objects flying towards or away from them. However, if they fly rectangular and the closing speed drops near zero, there is a high chance they it will lose lock.
 

 

Edited November 27, 2022 by Mike_Romeo

[Default774]

47 minutes ago, Mike_Romeo said:

Looks to me like the missile was notched. Missiles are using a doppler radar that detects targets by speed difference against the ground. So they only can detect objects flying towards or away from them. However, if they fly rectangular and the closing speed drops near zero, there is a high chance they it will lose lock.
 

 

 

I know what notching is.

A quick look at the tacview shows that the relative angle is around 50 degrees; nowhere near enough to notch the missile. Not to mention this test was performed over water, which effectively prevents notching as of 2.8.

Edited November 27, 2022 by Minimalist

[Маэстро]

On 11/27/2022 at 3:35 AM, Minimalist said:

The AIM-120 does not consistently acquire a flanking target on active, even when the missile is fully supported through the entire midcourse stage. The missile never acquires the target even though it is being provided datalink updates from the parent aircraft.

In this particular case the problem is aircraft rolling at lauch. High roll rate causes intertial acceleration(see Coriolis theorem) which affects INS alingment. Noticable errors in INS data prevent target lock, because targeting data and real target data does not mutch.

[Papa Saubär]

20 hours ago, Маэстро said:

In this particular case the problem is aircraft rolling at lauch. High roll rate causes intertial acceleration(see Coriolis theorem) which affects INS alingment. Noticable errors in INS data prevent target lock, because targeting data and real target data does not mutch.

The aircraft, which is launching the AIM120, isn't rolling at the launch. The rolling begins after the launch.

The stable platform is therefore given.

[Маэстро]

1 hour ago, Papa Saubär said:

The aircraft, which is launching the AIM120, isn't rolling at the launch. The rolling begins after the launch.

Hm, perhaps there is some difference between public and internal DCS version. In attached tracks I see player press the launch button and immediately begins rolling, so missile moves along the rail of already rolling aircarft.

[Default774]

4 hours ago, Papa Saubär said:

The aircraft, which is launching the AIM120, isn't rolling at the launch. The rolling begins after the launch.

The stable platform is therefore given.

The tacview is inaccurate in this case, missile was fired while rolling.

https://streamable.com/5ipq6c

[AeriaGloria]

On 11/30/2022 at 3:13 AM, skywalker22 said:

You think DCS has this simulated? But in anyway case, missile being that close to the target as in this our case, it has gone pitull for way before - so missile is guided by its onboard radar.  And this should be a hit. Could be a bug.

He works for ED. Coriolos theorem and Kalman filters are implemented as part of the new AIM-120 seeker model. Different variable speed and range gates. INS errors. Beyond the seeker even the speed of the electronic actuators for the fins are simulated. Stability changes throughout flight as motor burns and shifts weight. 
 

And a couple years ago, proportional navigation and advanced proportional navigation were the hottest missile seeker tech in DCS the AMRAAM is being simulated as deeply as possible using reverse engineering to get around classification, I think some people see the seeker issues that haven’t been worked out and call it crap. But when it’s done and works proper it will be an incredible simulation. I’m pretty sure one of the only really things that hasn’t been addressed about the seeker yet is husky modes.