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HARM seeker in PB and EOM modes activates too early during flight.


VKing

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If the HARM is fired in PB (or EOM in the F-16), the expected behaviour is that the HARM will loft and turn towards the selected steerpoint or target point, then dive towards the target area and start looking for a radar of the selected type to home in on.

What appears to be happening, is that the HARM seeker activates immediately upon launch. If it doesn't see a radar, or if the radar is active the entire time the HARM is in flight, it will fly the correct flight path. However, if the radar turns off at any point during the flight, the missile will go dumb and forget its target position, and glide straight past it.

In the first two tracks, which is the same scenario in the F-16 and F-18, to show there is no issue with a particular aircraft, there is one SA-6 radar at steerpoint 2. First one HARM is fired against a non-existent SA-2, and one against the SA-6. When the first HARM is about to strike the SA-6, a third is fired, also against the SA-6.

Observe that the first two missiles loft and dive towards the target area as expected, even though there is no SA-2 radar for the first missile to spot. The third missile fails to initiate its dive, and as such will completely miss the target area.

In the third track, the radar respawns (placeholder for a radar deactivating and reactivating), and since the second HARM does not follow the correct flight path, it misses the second radar since it is outside of the HARM's FOV when it activates.

The fourth track demonstrates that the HARM seeker activates far too early. Even in EOM mode, which is supposedly the most restrictive in terms of precision required of the target location, the missile turns to seek onto a radar more than 20 nmi away from its given target position.

HARM_EOM_Tracking_bug_F-18.trk HARM_EOM_Tracking_bug_F-16.trk

HARM_EOM_Tracking_bug_F-16_radar-reactivates.trk

HARM_EOM_Tracking_bug_F-16_activation-range.trk


Edited by VKing
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  • VKing changed the title to HARM in Pre Brief modes does not follow correct flight path if target radar shuts down during flight.
  • 3 weeks later...

I can believe that's how the weapon is supposed to work after the sensor turns on. You would like the missile to continue towards the target if it turns on again, but this is contingent on the missile being close enough that it's actually flying at the target instead of still lofting.

The problem seems to be that the sensor turns on almost immediately upon launch instead of when it reaches the target area it's supposed to search in. So instead of looking at a small area for a specific radar, it searches basically half the map.

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  • VKing changed the title to HARM seeker in PB and EOM modes activates too early during flight.
  • 4 weeks later...

Another track, recorded with 2.8.4.38947 MT.

This shows four HARMs fired at four different SAMs, but when the SAMs activate, all four HARMs turn to the same radar, leaving three of the four SAM sites unengaged.

Edit: Second track with F-18. This time two radars got hit because they activated later and one of the HARMs spotted one radar while the three others went for another.

HARM_EOM_Tracking_bug_F-16_InadvertentFocusFire.trk

HARM_EOM_Tracking_bug_F-18_InadvertentFocusFire.trk


Edited by VKing
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