investigating Su-27 / Su-33 / MiG-29 bug: wrong transition from Radar to EOS

[BlackPixxel]

When a target is locked with radar and goes through the notch in a lookdown situation, then the Flanker will switch to an EO lock as soon as the radar lock is lost in the notch.

 

When EO lock is not possible, for example because the target is below the nose and as such outside of the IRST gimbal limits, then the radar uses radar memory and is able to reacquire the target when it leaves the notch quick enough.

 

If now the Flanker maneuvers in such a way that the target would be inside of the IRST gimbal limits and if the target's heat signature is strong enough, then the following bug will happen:

The stable radar lock will switch to an EO lock for no reason. The player then has to manually disable EO to force the radar back on.

 

 

The attached trackfile shows the issue:

 

I engage the low flying target and I bank away, so that the target is below my nose. The target changes aspect, so it turns through the notch. While it turns through the notch, the radar loses lock, but thanks to radar memory it reacquires the target as soon as it left the notch. I turn back towards the target, and as soon as the target is within the gimbal limits of the IRST, the lock switches from a radar lock into an EO lock. This is a bug.

 

 

Appart from that it would be nice if the Radar/IRST sensor fusion was properly implemented. Even a notching taret should still be painted by the radar, because both channels work together and not exclusive. So a low flying and notching target would still be painted for R-27R/ER missiles. But in DCS the radar shuts of the second the target notches and it goes into an EO lock.

radar_irst_bug.trk

[Ironhand]

...

The attached trackfile shows the issue:

 

I engage the low flying target and I bank away, so that the target is below my nose. The target changes aspect, so it turns through the notch. While it turns through the notch, the radar loses lock, but thanks to radar memory it reacquires the target as soon as it left the notch. I turn back towards the target, and as soon as the target is within the gimbal limits of the IRST, the lock switches from a radar lock into an EO lock. This is a bug...

 

FWIW, I watched your TRK and the target was outside your radar's gimbal limits for awhile. EOS locked waiting for the radar to reaquire. I took over your TRK and, once the target was inside radar's gimbal limits again, the radar relocked (EORL) and I was able to launch another missile.

[BlackPixxel]

FWIW, I watched your TRK and the target was outside your radar's gimbal limits for awhile. EOS locked waiting for the radar to reaquire. I took over your TRK and, once the target was inside radar's gimbal limits again, the radar relocked (EORL) and I was able to launch another missile.

 

Please look again, I am at no point outside of my radar gimbal limit, at least when I replay the track on my PC.

 

If I was outside of my radar gimbals then the ATK symbol would flash.

 

The ATK symbol only flashes because the radial closure speed of the target is within the notch filter bandwidth for a moment (target is notching for a moment when it turns cold).

 

Normal DCS Flanker logic is now to switch to IRST lock. But I have the target outside of the IRST sensor gimbals (below my nose). So the radar stays in memory mode. The bug is now that the Flanker in DCS still wants to go into EO mode. So when the target is cold with a solid radar lock, and I roll out, the lock turns into an EO lock as soon as the target is back within my gimbal limits. This is a bug, the lock should stay a radar lock in this case.

[Ironhand]

Please look again, I am at no point outside of my radar gimbal limit, at least when I replay the track on my PC.

 

If I was outside of my radar gimbals then the ATK symbol would flash.

 

The ATK symbol only flashes because the radial closure speed of the target is within the notch filter bandwidth for a moment (target is notching for a moment when it turns cold).

 

Normal DCS Flanker logic is now to switch to IRST lock. But I have the target outside of the IRST sensor gimbals (below my nose). So the radar stays in memory mode. The bug is now that the Flanker in DCS still wants to go into EO mode. So when the target is cold with a solid radar lock, and I roll out, the lock turns into an EO lock as soon as the target is back within my gimbal limits. This is a bug, the lock should stay a radar lock in this case.

When I watched your track, I kept an eye on the HDD and the target definitely moved outside prior to the loss. So perhaps the track plays differently for you and me. The ATK symbol flashes, the switch to EOS occurs. I took control shortly after you began to turn back, continued the turned into the target, got the EORL symbol and launched.

 

I should have saved my track but didn’t think to.

[BlackPixxel]

Did you maybe confuse the gimbal limits with the R-27ER launch zone on the HDD? Those are much narrower than the radar gimbals (although they should not be that narrow as the R-27ER has +/-50°).

 

I never exceeded the radar gimbals, just look at the dot in the HUD. the dot can be further right than the angle number next to the horizon bar, and my dot never went that far.

 

Here is a video of the track:

Edited May 13, 2020 by BlackPixxel

[Ironhand]

Did you maybe confuse the gimbal limits with the R-27ER launch zone on the HDD? Those are much narrower than the radar gimbals (although they should not be that narrow as the R-27ER has +/-50°).

 

I never exceeded the radar gimbals, just look at the dot in the HUD. the dot can be further right than the angle number next to the horizon bar, and my dot never went that far.

 

...

Yes. My error. You were within the gimbal limits.