AI strange escort behaviour

[PL_Harpoon]

I just noticed something strange while playing through several amphibious strike missions.

Usually, if you fire a torpedo at a convoy outside their detection range they will turn and run as soon as they detect a torpedo. This is fine.

What's not fine is that after then get out of danger zone the escort ships seem to just turn around and converge on the datum at whatever speed they are (often at flank speed). This renders them totally blind so you can just stay in one place and pick them off one by one as they come close.

Instead I think they should first fire a snapshot torpedo and then converge as slowly as possible (or at least using sprint and drift) zig-zaging on the way.
Also, if there is a helicopter it should be send there ASAP. perhaps using dipping sonar in both active and passive mode.

So far I had problems with helicopter only if they were by accident close enough to hear my launch transient.

[Nippelspanner]

According to "Modern Submarine Warfare", this is pretty much authentic.
If a possub is detected, the ASW forces immediately leave formation and approach the last known position at high speed.

Ingame this seems to be the case, and I have witnessed surface ships launching helicopters that investigated my general area.

[PL_Harpoon]

Interesting.
That makes sense if the possible sub pos is outside of detection range.
But surely this doesn't means they need to go right on top of that position.

I've had ships sailing past me by 4KYDS that couldn't detect me because they were running at 30-something knots.

Shouldn't there be a "close enough" distance at which they'll begin their search?

[Nippelspanner]

I would assume so, this isn't described further, I think. Will have a look later.
But it only makes sense. Why would you steam into knife-fight range with a submarine?

But approaching the general direction at high speed to close distance and "block" the sub from the convoy seems logical.

[Julhelm]

One is a hunter, one is a killer. The killer who moves in for the attack does not need to hold contact with his own sensors - there is a datalink for them to share target information between them.

[PL_Harpoon]

I admit it sounds great in theory.

So, instead of arguing I'll try to record an example to show what I mean :)

[Ansgar Burkhard]

I admit it sounds great in theory.

So, instead of arguing I'll try to record an example to show what I mean :)

I can say it works. I just had a catastrophic mission of sinking a landing force where I got two escorts from the get go. The others closed in on me fast while the help dropped two torsos in my general area. And one of the destroyers kept sending missile torpedoes at me. I had 5 torsos in the Water at a certain point. One of them hit home. I also noticed the AI using passive torpedoes which is great.

[PL_Harpoon]

https://youtu.be/nWgH8Ub_eKs

Here's what I mean.
I've decided to upload the whole engagement (in case you want to see the whole picture), so the video is a bit lengthy. But if you want to skip to the action, it starts around 11 minutes.

As for the modifications I use, none of them affects ship's sensors or sub noise. And the TMA rate doesn't matter cause none of them actually detected my ship. The only modification that affect enemy behaviour is the increased noise of Mk48 which makes them try to escape sooner that in vanilla.
Oh, and I've also bumped helicopter's dipping sonar to 40 to see if it would make any changes. But as you can see near the end of a video, it's nowhere near my position.


BTW, again, sorry for the out-of-sync sound. It was recorded that way. It could be the FRAPS or the fact that I use a USB sound driver (probably both).

[Julhelm]

40 is crazy high for the dipper. It essentially turns it into BQQ-5.

Also, I looked at the values for your torpedoes and they seemed crazy high.

At the time of shooting, you are doing 5kts in the 688. It has a stock selfnoise of 115db, so that makes your output 120db. Now, a little earlier, we could see the Krivak had you on -10db passive. Now, the reason the Alligators turn away the instant you fire your torpedoes is not because THEY detect them. Alligators don't have sonar gear, so it must be that your torpedoes are loud enough for the escorts to detect them at the time of launch. That's why they know your exact position.

If you have a 20db advantage, but fire a torpedo that's well above that, say putting out 160db, you've just announced your presence. The Kresta and the Krivak both have the same Bull Nose passive/active, so it's a fair bet they both pick up your torpedoes and can triangulate your datum.

[PL_Harpoon]

40 is crazy high for the dipper. It essentially turns it into BQQ-5.

Yeah, I just bumed it for this test to see if it would change anything.

Also, I looked at the values for your torpedoes and they seemed crazy high.

I'm thinking of lowering them down, but I'm afraid that with shorter detection range the enemy will have problems with avoiding them again (currently with my mod if you fire a torpedo and brake the wire the enemy will most likely be able to avoid it; in vanilla game the torps almost always reached the target).

At the time of shooting, you are doing 5kts in the 688. It has a stock selfnoise of 115db, so that makes your output 120db. Now, a little earlier, we could see the Krivak had you on -10db passive. Now, the reason the Alligators turn away the instant you fire your torpedoes is not because THEY detect them. Alligators don't have sonar gear, so it must be that your torpedoes are loud enough for the escorts to detect them at the time of launch. That's why they know your exact position.

If you have a 20db advantage, but fire a torpedo that's well above that, say putting out 160db, you've just announced your presence. The Kresta and the Krivak both have the same Bull Nose passive/active, so it's a fair bet they both pick up your torpedoes and can triangulate your datum.
I'm ok with everything you described here. I think it's fine that launching torpedoes reveals your position and I definitely think it's good that the escort upon detecting a torp launch orders the merchants to run away. It seems consistent as after turning away they don't try dodge them. I like that.

What I don't like is that even though the enemy has my almost exact position they do nothing about it except rushing at it at max speed. The helicopter was in the air at the whole time (you can see it at 1:30 at bearing 104 and at 10:41 @ 112) yet after the whole engagement I've checked his positions and he was miles away (the smoke would've been seen from his position were he any closer). But the biggest issue here is that the escort blindly rushes into my torpedoes. Just look at the Krivak and Kresta at 16:50. If any of those ships would slow down for a second I'd be in a huge problem. Instead, even after I fired my torpedo at the Kresta which should reveal my position, the Krivak, after initial dodge was still running at full speed towards the previous datum.

You said yourself they had my exact position, but not a single torpedo was fired.

TL;DR - In my opinion this shows two problems with the AI:
Shouldn't they slow down at a certain distance from datum to acquire a contact and open fire?
Shouldn't they immediately send a helicopter once they detected my torpedoes?

[Julhelm]

I would have to look at the AI debug overlay to accurately understand what's going on, but the fact they detect your torpedo does not necessarily mean they have contact on you, especially since they likely would not pick up the 5db transient. It seems to me the AI has no way of knowing if it detected torpedoes that was just fired, or torpedoes that were fired 5 minutes ago. It's a different scenario from where you launch a missile and create a datum because the missile cannot be run out to a location then launched, but torpedoes are fairly covert in comparison which is why they're not raining Silexes down your position.

[PL_Harpoon]

That's fine.

I just wish they'd be a bit more effective in their search.

Once I've learned to begin my attacks outside of their detection range the escort stopped being a threat.

[Julhelm]

How could they be more effective in your opinion?

[PL_Harpoon]

Here's what I think would help:

1. Datum - they should be updated (perhaps there's some bug preventing this ATM)
2. Helicopters - after detecting an incoming torpedo they should be immediately send to investigate the datum. (btw, in one TLAM mission I noticed that Bears and Mays behave like that, but helicopters stick to their regular search patterns)
3. Surface ships - I think it's safe to assume, that any captain knows the detection ranges of his sonar under the present conditions. So, I suggest that after they rush at max speed at the datum they should slow down as soon as it is within the detection range.

Notice that in all f those cases the datum might still be wrong. I'm not asking for AI that magically know your position. Instead with those behaviours implemented you will need to either clear the datum as soon as possible after the attack or present the enemy with false one (like clever usage of wire-guidance).