investigating AIM-7 is a FOX-3 again

[al531246]

The AIM-7 has once again acquired the ability to self-guide to aerial targets. I've confirmed this on the AIM-7F, I've not checked other variants of the AIM-7 but I suspect it will be the same. In the following series of event I am the player герой. 

1st Event
In the Tacview attached below skip to 11:01:20. Observe the AIM-7F launched by player 'Baguette 3-5 - The Skyline' (F-14A) track to player герой in an F-15C. Timestamps:

11:01:24 - F-14A launches AIM-7F
11:01:50 - F-14A destroyed by Frosty in F-15C (note the F-14A's AIM-7F continues tracking)
11:02:15 - AIM-7F impacts герой F-15C despite being unguided

2nd Event
In the second instance герой launches an AIM-7F onto an F-14A 'Sapphic 1-1'. The F-14A is destroyed by a friendly F-15C. The lock on the F-14A is dropped by герой. The AIM-7F guides itself onto a new target - a friendly F-15C. Timestamps:

11:44:15 - герой launches AIM-7F
11:44:23 - F-14A destroyed by Frosty in F-15C
11:44:29 - STT lock by герой on F-14A is dropped > Missile then acquires Frosty in F-15C (uncommanded)
11:44:51 - AIM-7F impacts Frosty in F-15C

Don't have a track file because I don't record tracks. They're always broken. 

Tacview-20221230-201455-DCS-80s-production-V42-OVC.zip.acmi

Edited January 17, 2023 by al531246

[FigPucker]

Condensed TacView just showing the engagement attached.
AIM-7FSUPERMISSILE.zip.acmi

[Flappie]

@al531246 Are you aware the AIM-7 is Home On Jam-capable?

 

[al531246]

34 minutes ago, Flappie said:

@al531246 Are you aware the AIM-7 is Home On Jam-capable?

Aye. However I would point out;
1) I didn't launch in HOJ. It was STT guidance. The AIM-7 would not auto revert to HOJ after dumping lock. 
2) AIM-7F doesn't have HOJ capability

UPDATE: AIM-7F does have HOJ capability per ADA142508 - https://apps.dtic.mil/sti/pdfs/ADA142508.pdf
But this doesn't negate the issue. Point 1 still stands.

Edited December 30, 2022 by al531246

[Flappie]

9 minutes ago, al531246 said:

2) AIM-7F doesn't have HOJ capability

UPDATE: AIM-7F does have HOJ capability per ADA142508 - https://apps.dtic.mil/sti/pdfs/ADA142508.pdf

Thanks for pointing that out.

We need a short DCS track to show this issue to devs (Tacview ACMI tracks are of no use to them).

[al531246]

9 minutes ago, Flappie said:

Thanks for pointing that out.

We need a short DCS track to show this issue to devs (Tacview ACMI tracks are of no use to them).

Is it absolutely necessary to provide a track..? It's not a bug that needs to be identified. It's an incorrect programming of the missile's logic.

[Flappie]

1 minute ago, al531246 said:

Is it absolutely necessary to provide a track..? It's not a bug that needs to be identified. It's an incorrect programming of the missile's logic.

Devs always ask for tracks, believe me. And when it comes to weapon guidance, devs definitely need tracks, yes. Please.

[al531246]

Just now, Flappie said:

Devs always ask for tracks, believe me. And when it comes to weapon guidance, devs definitely need tracks, yes. Please.

Okay. I will attempt to recreate for a track. 

[Flappie]

Thanks. Short SP tracks over Caucasus are prefered.

Edited December 31, 2022 by Flappie

[near_blind]

How come?

[al531246]

On 1/3/2023 at 5:59 PM, near_blind said:

How come?

Because the missile must be launched in HOJ mode. HOJ guidance is completely different from normal guidance.

Also the AIM-7 doesn't have a logic which would auto-select HOJ if a lock is lost. 

[al531246]

@FlappieTrack acquired. Tacview attached as well.

Brief:
Me and a buddy flew head on. He would activate his ECM (Su-27) one second after receiving the Missile Alert warning on RWR. Therefore it is not a HOJ launch. It is an STT launch. He then killed me (F/A-18C) leaving the AIM-7 without guidance. The missile still guided to his aircraft and only stopped tracking when ECM was disabled.

Timestamps:
08:26:39 - We both launch missile
08:26:41 - Su-27 activates ECM
08:26:58 - F/A-18C explodes, AIM-7 continues tracking
08:27:05 - Su-27 turns ECM off, AIM-7 stops tracking

You can see the moment the ECM turns off and missile drops lock in the graph below.

Tacview-20230117-230159-DCS-HOT_SHOTS.zip.acmi server-20230117-220517.trk

Edited January 17, 2023 by al531246

[Coxy_99]

SARH missiles in DCS have a 4 second memory mode, So even if the lock is broken the missile will still track if only for a short while before it dies (Depends on range speed and aspect of the target) Plus what your describing is called HOJ once that ECM is on. ECM is basic on/off. Does not matter if you launched in STT first or not missile will just guide into HOJ because ECM switched on.

Edited January 17, 2023 by Coxy_99

[al531246]

4 hours ago, Coxy_99 said:

Plus what your describing is called HOJ once that ECM is on. ECM is basic on/off. Does not matter if you launched in STT first or not missile will just guide into HOJ because ECM switched on.

You've misunderstood. The opponent's ECM was off at the time of launch. Launch + 2 second the ECM was activated. The missile then holds the lock and tracks until ECM is deactivated, regardless of whether the guidance radar is alive or not.

A standard STT launch is lead pursuit. A HOJ launch is pure pursuit. The missile is operating in lead pursuit throughout, confirming the presence of a bug.

Basically ECM being on turns your FOX-1 into a FOX-3. This is obviously incorrect.

[Ironhand]

19 minutes ago, al531246 said:

You've misunderstood. The opponent's ECM was off at the time of launch. Launch + 2 second the ECM was activated. The missile then holds the lock and tracks until ECM is deactivated, regardless of whether the guidance radar is alive or not.

A standard STT launch is lead pursuit. A HOJ launch is pure pursuit. The missile is operating in lead pursuit throughout, confirming the presence of a bug.

Basically ECM being on turns your FOX-1 into a FOX-3. This is obviously incorrect.

Excuse my ignorance. How do you know that ECM engaged 2 seconds after launch? Just curious.

[al531246]

13 minutes ago, Ironhand said:

Excuse my ignorance. How do you know that ECM engaged 2 seconds after launch? Just curious.

Because I made the track with my buddy about 8 hours ago.

[Ironhand]

32 minutes ago, al531246 said:

Because I made the track with my buddy about 8 hours ago.

I’m aware of that. I’m just asking if he told you it was active only after the indicators were solid, since there’s a 15 second delay between the time you flip the switch and the time it comes on.

Edited January 17, 2023 by Ironhand
Grammar

[al531246]

9 minutes ago, Ironhand said:

I’m aware of that. I’m just asking if he told you it was active only after the indicators were solid, since there’s a 15 second delay between the time you flip the switch and the time it comes on.

 

I believe he activated it (as in hitting the E key) immediately post launch. 

[Ironhand]

14 minutes ago, al531246 said:

I believe he activated it (as in hitting the E key) immediately post launch. 

In that case, assuming the timeline you described above is the correct one, his ECM turned on at 08:26:56, roughly 2 seconds before your aircraft exploded and right around the time that the AIM-7’s Gs and turn rate suddenly increase on the chart.

EDIT: Just making the observation.

Edited January 17, 2023 by Ironhand

[al531246]

6 minutes ago, Ironhand said:

In that case, assuming the timeline you described above is the correct one, his ECM turned on at 08:26:56, roughly 2 seconds before your aircraft exploded and right around the time that the AIM-7’s Gs and turn rate suddenly increase on the chart.

My buddy in the Su-27 also reverses his crank at the same time. You can see this in the tacview. I think it's more likely the missile is reacting to his defensive maneuvers. 

[Ironhand]

Ahh…OK. I’m not where I can check the Tacview or TRK. OTOH, assuming he thought the ECM was on as soon as he pressed the “E” key, you’ll need to revise your timeline.

[al531246]

1 hour ago, Ironhand said:

Ahh…OK. I’m not where I can check the Tacview or TRK. OTOH, assuming he thought the ECM was on as soon as he pressed the “E” key, you’ll need to revise your timeline.

It's in my post with the graph image, it's an attached file. Whether the ECM came on 1 second or 15 secs after launch is inconsequential; the missile was not launched in HOJ nor was it flying a HOJ pursuit course. It's performing a guided intercept without guidance. It's that simple.

[Ironhand]

1 hour ago, al531246 said:

It's in my post with the graph image, it's an attached file. Whether the ECM came on 1 second or 15 secs after launch is inconsequential; the missile was not launched in HOJ nor was it flying a HOJ pursuit course. It's performing a guided intercept without guidance. It's that simple.

I'm neither advocating nor criticizing your conclusion. I'm simply pointing out that your documentation contains an inaccuracy. Change it or don't change it. It's no skin off my nose.

[FigPucker]

"aKsHUaLlY"
You're wrong.

ECM was activated immediately after AIM-7 launch, warmed up over the next few seconds, and was emitting by the time the F/A-18C was destroyed.
OP has effectively demonstrated that the AIM-7 has reverted to HOJ, even though it was not launched in such a mode. 

 

[BIGNEWY]

folks, treat each other with respect please. 

We are taking a look at this issue. 

thank you