[WAD+FIXED] AMRAAM overshoot

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[WAD+FIXED] AMRAAM overshoot - 3/21/2019 8:18:27 PM

sschnei244

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Since I uploaded the 1.15.1 version of CMANO I have had two instances of AMRAAMS overshooting targets. In both cases, the targets
were being tracked by the firing aircraft for the duration of the engagement. The missiles did not begin to descend to the
altitude of the targets until their active radars came on. By then it was too late for them to intercept. I have uploaded one
saved example.

I took another look at the file. The two AMRAAMS fired at the Su-34 have datalinks back to the launching aircraft, the two
AMRAMMS fired at the Su-30 do not. This would explain the strange behavior of the missiles fired at the Su-30. The F-16CM has
8 datalink channels for AMRAAM so the datalinks should be there.

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< Message edited by Dimitris -- 6/19/2019 7:54:49 AM >

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RE: AMRAAM overshoot - 4/21/2019 2:01:16 PM

Dimitris

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Thanks, we'll take a look.

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RE: AMRAAM overshoot - 4/22/2019 10:53:17 AM

Dimitris

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Checking this at the moment. For some reason, the easternmost pair of AMRAAMs do not have any datalink devices on board. This is quite curious.

If possible, can you provide a save at a prior point in the engagement? (Ideally pre-fire). This would allow us to walk through the entire process and see what happened.

Thanks.

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RE: AMRAAM overshoot - 4/22/2019 5:59:43 PM

mlluell

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I've made this simple scenario of 4 F-35 vs 4 J-20 with nothing else, sometimes no missile overshoots, sometimes one, two or even half of them overshoot one time. Usually the ones to overshoot are the ones that are fired first.

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RE: AMRAAM overshoot - 5/5/2019 10:15:00 AM

amizaur

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Has this been resolved ? I still have this problem in my Steam version of CMANO after manually upgrading it to 1009 period 27 period 14 (forum engine interpreted version number as a telephone number :/).

Long range AMRAAMs are more often than not overshooting targets that are maneuvering and/or diving to avoid. Amraams arrive at activation point very high (like 18000m) while target is already at few thousands meters or even at sea level, and then AMRAAMs can't aquire and overshoot.

Part of the problem is that AMRAAMS start their dive to targets too late, other part of the problem is that as soon as they turn on their onboard radars they doesn't seem to use (or get) target position updates anymore from launching platform. So if they don't aquire immediately the (maneuvering or diving) target soon moves out from their acquision cone and we get an overshoot. This is not as it works IRL, AFAIK. If launching platform provides target position updates the missile uses it at least as long as it doesn't lock target with it's own radar (and probably even after that).

Sometimes I see that target position is not updated even for missiles in midflight so they arrive at completly wrong intercept point agains maneuvering targets even though I tracked targets all the time with launching platform's radar. The radar of launching platform is powerfull enough to ensure continuos tracking of targets, it's WELL within their range, it's not lost tracking issue.

I can make a save with this issues showing up but before that I'd like to ask if the issue was adressed and it's cause pinpointed already (in what patch number was it correced?) so I probably made some mistake during manual updating, or maybe the problem is still "active" ?

Edit: in the test scenario posted above, once the semi-stealthytarget J-20s dive to sea level (while shooting aircraft are left at 10.000m) it's hard to target them at all with AMRAAMs because at short range AMRAAMs immediately turn on their radars and do not follow target maneuvers at all anymore, at least untill acquiring, which usually doesn't happen because the maneuvering target moves out of acquision cone (and the cone is short because of stealthy target). If the shooting aircraft is tracking the target and has free datalink canals it should provide updates to it's missiles in flight with target data as long as it can - which is especially important against stealthy or jamming targets where effective missile lock-on range can be short. And missiles should use that data if they need.

BTW this way while the missile is still being fed with good quality target data, and assuming it's own on-board INS navigation is precise enough too (more modern AMRAAM versions/Meteor ect) then enabling missile's on-board radar can be delayed untill few seconds before impact which gives target aircraft minimum time to react. In other case, if the launching aircraft has to turn away and disengage, the missile if it's past the activation point goes pitbull in the moment the datalink is terminated and tries to search on it's own.

< Message edited by amizaur -- 5/5/2019 1:05:48 PM >

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RE: AMRAAM overshoot - 5/6/2019 2:56:24 AM

Zanthra

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Currently the AMRAAMs are dropping their datalink when the target is in seeker range, regardless of whether they have acquired their target or not (perhaps it's better to say the aircraft drops the datalink, as they will clear they engaged offensive tag for guiding the missiles at that point, but they would only know if the seeker had aquired the target on the two-way AIM-120D missile). Once they drop the datalink they just fly straight, and if the target radar signature is small and evading, they have a fair chance to just pass the target by without seeing it.

< Message edited by Zanthra -- 5/6/2019 3:01:07 AM >

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RE: AMRAAM overshoot - 6/17/2019 8:37:55 PM

mlluell

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Any update on this? I've just tested it again and it still happens the same.

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RE: AMRAAM overshoot - 6/17/2019 9:33:06 PM

Dimitris

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Not yet, sorry. We've been busy with other things. We'll take a look when we can.

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RE: AMRAAM overshoot - 6/18/2019 8:24:49 AM

Dimitris

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Okay, I had a look at this today, using B1009.31.1 and the "4 F-35 vs 4 J-20" save (which BTW is a rather poor example for lofting, because at the distance the AMRAAMs are fired, there is no room to loft, so they effectively fly straight in).

For comparison, I also used another test scenario against non-VLO targets (Su-30MKI & A-50) where there was sufficient distance to exploit lofting.

1) There is an issue with excessive aircraft climb/dive rates, which can cause a target (such as the J-20 in this case) to very rapidly get out of the AMRAAM acquisition cone in the vertical plane. This has been fixed for the next update.

2) Re: AMRAAMs severing their datalink once they go autonomous. To our knowledge, this is the RL behavior. Even the AIM-120D (and Meteor AFAIK) with its two-way datalink does this. Our available information does not suggest any torpedo-like "offboard seeker" ability. If you have sources to the contrary that you can share, please do.

3) Re: LO targets having a good chance of evading seeker acquisition even if they are within the physical cone. Well yes, that's part of the appeal of LO/VLO.

4) I did not observe any pre-programmed "high diver" AMRAAM behavior. (I say "pre-programmed" because in one case, a lofting AMRAAM was re-directed to a tree-top level target which had just evaded another shot. The missile was originally cruising high for a more distant target, but because of the redirection it had to abruptly snap down in order to catch up with the new target in the weeds. This was the correct and desired behavior.) If you do notice any such behavior, please open a new thread specifically for this.

A general observation: You are shooting at highly agile (e.g. Su-34/35) or LO/VLO (J-20) aircraft, or both (e.g. F-22, Su-57). _Of course_ they'll pull out all the stops to ruin your shot. _Of course_ some of your shots will miss, or be physically outmanouvered (especially at long range). Plan for that.

The real criterion is: Do the same difficulties appear when engaging "easy" targets? I haven't observed this in repeated tests.

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RE: AMRAAM overshoot - 7/4/2019 10:46:23 PM

Zanthra

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I think I found out what the issue is with this. Right now AIM-120Ds are turning their 5nm (30,000 feet) seeker on while they are at an altitude of more than 60000 feet (10nm). They only use the ground distance to target to determine when to turn the seeker on. As I understand it radar range limits are 3D space, so the weapon is going active at 11-12nm from target (most fighter targets are at only a few hundred feet above the ground before the missile gets there.)

Can the weapons be changed to only turn their seeker on when within seeker range of target in 3D space rather than ground distance to target?

PS: Just noticed I had somehow got rolled back to the current steam version which has the 5nm seeker on the AIM-120D, where the recent 1009.31.1 has 15nm seeker range, and the problem is much less as the ground distance is the longer side of the right triangle with the newer database info.

< Message edited by Zanthra -- 7/8/2019 7:24:47 AM >

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RE: AMRAAM overshoot - 7/10/2019 11:02:43 AM

Dimitris

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quote:

ORIGINAL: Zanthra

I think I found out what the issue is with this. Right now AIM-120Ds are turning their 5nm (30,000 feet) seeker on while they are at an altitude of more than 60000 feet (10nm). They only use the ground distance to target to determine when to turn the seeker on. As I understand it radar range limits are 3D space, so the weapon is going active at 11-12nm from target (most fighter targets are at only a few hundred feet above the ground before the missile gets there.)

Can the weapons be changed to only turn their seeker on when within seeker range of target in 3D space rather than ground distance to target?

PS: Just noticed I had somehow got rolled back to the current steam version which has the 5nm seeker on the AIM-120D, where the recent 1009.31.1 has 15nm seeker range, and the problem is much less as the ground distance is the longer side of the right triangle with the newer database info.

That's an excellent point, thanks. I'll check to see if we currently determine the "sensor standoff" distance based on horizontal or slant range.

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