correct as is HARM EOM Mode Behaviour

[Duervol]

Hello together,

I have discovered some interesting behaviour of the HARM when shot in EOM mode without spike or nails on the RWR.
When shot, the Harm overshoots the steerpoint and when the plane gets the ping, the harm turns itself very harsh and track the target.
 

Is this really possible? 

Trackfile and Tacview attached.

Thank you!

Harm-EOM-Behaviour.trk HARM-EOM-Behaviour.acmi

[Bricux]

Hey, I think that behavior of HARM in EOM mode is fully correct. Remember that in any POS mode, after launch, HARM using INS as navigation to the designed steerpoint. After reaching desired distance to steerpoint, HARM turns own seeker and then guiding itself to the target.

I assume that You just noticing that moment of activation HARM seeker. EOM is specific, it has very narrow seeking footprint.

I hope it helps. Notice that on my picture HAS is described as TOO.

Edited November 16, 2021 by Bricux

[Duervol]

Thanks for calrification this makes sense.
But without any spike etc - maybe chosen the wrong target (just for a simple situation) or even the SAM is not tracking etc - the harm would just overfly the steerpoint and do nothing?

Edited November 16, 2021 by Duervol

[Moonshine]

EOM is still using a waypoint as navigation and on your HARM page you set the desired emitter to launch at. it will guide towards the waypoint and try to find set emitter and destroy it. if it finds nothing at all it will simply impact on the waypoint as it does in the other PRE modes (PB and RUK) as well

 

[Duervol]

This is the same as I have expected it should work.

Please look at the Tacview or Trackfile, I have shot a second Harm an it just passes the Steerpoint without tracking anything.

 

Edit:
Added another Trackfile with shot Harms without any targets - 2 of 4 are overshooting the steerpoint.

Harm-EOM-no-target.trk

Edited November 16, 2021 by Duervol

[Moonshine]

cant check tacview as of now, will do when able. fair point then, "usually" it should guide towards the steerpoint if it doesnt find anything. if it didnt you might have a point that it isnt behaving as it should. Unless im missing something and someone can clarify and lecture me on how it should actually work

[Duervol]

It is indeed the question why it even overshoots? If it should fly to the steerpoint, then there is no reason for overshoot an track.
Unlike my second Trackfile added in my post before, 2 of 4 harms are not overshooting, the rest ist overshooting.

[Bricux]

Do You place enemy radar in RED ALARM state? Otherwise radar is turned off at the beginning and will turn on if You enter in his detection range. It may answer spike correlation.

Edited November 16, 2021 by Bricux

[Duervol]

I have set it to RED and also waited until the SA-11 ist deployed.

Case of this Situation is a reconstruction of a Operation that was flewn yesterday. There we noticed this behaviour and I claimed that the HARM was shot without any spike to the plane rather than talking directly from a bug.

Took me nearly 1 hour to recreate this specific behaviour and it was intended to shot without direct spike, let the harm overshoot an take the spike in the right spot.
During my try and error for recreation, I also noticed that there is absolute no problem when the SAM is spiking the plane and the harm is released.

But with the current thought, it looks like to be correct to track with the spike and not track without spike - but the overshooting would be not correct?

 

Edited November 16, 2021 by Duervol

[Bricux]

@Duervol thank You for patience.

I check Your track and made my own test. At first my results. HARM seeker do not depend on Your plane RWR. I shoot to SA-19 from 60nm (both PD and EOM), radar have any chance to see me, and in both tests rockets hit.

Now Your track. Firstly I watch it, later played on my own. At first I noticed that You launched Your HARM from very short distance. So I assume that your first rocket, just stop to loft and then steer itself to the target. Second one, even don't finished lofting and already pass by Your steerpoint. Later I played Your mission, just fired HARM from greater distance and it work well. Next I tested even closer range, shoot 2 rocket (PB and EOM). Both fly above target, turn back and attack radar from the back.

So my conclusion is that HARM in EOM/PB have like couple phases of flight. 1 - launch; 2 - lofting with rocket motor; 3 - lofting w/o rocket motor; 4 - INS guiding; 5 - seeker guiding.

In this case Your rockets, have no time to stop lofting and start guidance. Your attack distance is so short that rocket must like turn back to the target. I think better mode for this situation will be RUK (loft rocket little bit by Your plane and shoot). In my test rocket hit hypersonic with rocket motor on.

Thanks

[BIGNEWY]

I have made a report for the team, 

it is worth mentioning the waypoint is at 6562ft and maybe playing a part in this. 

[BIGNEWY]

Checked with the team, in this case it is correct as is, due to the waypoint being at high altitude and not on the deck the missile just catches the SAM activation and has enough altitude to dive and return to target. 

thanks

[Frederf]

HARM has special target-isolation/flex logic so it's not a simple matter that an EOM shot against a silent emitter will just crash into the ground at the destination. This missile may keep maneuver potential to the original destination to only a certain point in the trajectory. Highlight "SD" on the target-isolate option to ensure the missile will not glide. All other options: normal, isolate, NC may glide. Ah, it's not modeled.

EOM is specifically to search an area narrowly against a known threat location. Currently if there is another emitter far away from destination the missile forgets its primary mission very early in the flight and goes for alternate target. This is bad since original zone is ignored just because there is no emission at detection so early in the flight.

The question of a HARM reacting to an emitter of assigned type dramatically off-axis is an interesting one. In my test I have found that EOM will react to new emitter very far away from typical EOM search footprint. It is expected that EOM in terminal phase is only searching for emitters in small footprint around destination. Track provided shows EOM missile discovers new emitter about 90 degrees right azimuth at greater than 9nm from target destination.  Other missile doesn't see this emitter as it's about 120 degrees off azimuth.

It seems that EOM search footprint is too large. In terminal phase if previously undetected emitters are active outside EOM search footprint should be ignored. The track can be used to try turning off-path emitter at different times but it looks like the full antenna az/el mechanical limits are being used for search zone size.

 

F16 EOM Footprint.trk

[Duervol]

Thank to all, very much information and insight on this specific behaviour.

Stpt height can indeed be a reason for this one, sadly I cannot recheck if it was the same at the mission itself but I will have a look at it in the future.
 

Also learned a lot about this mode and the harm itself.

Hopefully this HTS Video from today will happen soon in a Patch
 

Cheers!