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Old 10-25-2019, 07:16 PM   #1
Fidd
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Default Duration of asdic searches?

1. If we allow that the time a destroyer can take to prosecute asdic searches and attacks is dependant on not wishing to leave the convoy weakly or unprotected, then it follows that the faster the ship prosecuting the attack, the longer it likely to remain hunting for the attacking U-boat.

2. So, if we can further estimate that the more, numerically, escort ships are present, the less anxious a captain of a destroyer would be in leaving the convoy to continue attacks on a detected U-boat, and the longer he'd spend trying to reacquire it if he's lost contact on asdic.

At which point, the difference in speed between maximum convoy speed, and maximum speed of the warship gives us:

x (time) x (y # of warships remaining in convoy)/z (# of warships continuing attacks on detected u-boats) as a mathematical approximation of how long a warship might continue to hunt for a U-boat once detected.

Following the formula above, a lightly escorted early war convoy of corvettes, will not prosecute asdic searches for nearly as long as one with 3 or 4 much faster destroyers...

It'd certainly make life more interesting in the mid to late war encounters, if a similar formula was used to determine how persistant enemy warships were in searching and depth-charging. As you can probably surmise, I think that currently the duration of searches by escorts is woefully inadequate.

On an unrelated note, and this may have been asked for before, but please can we have the default option of anglicized graphics on depth-gauges and the telegraph etc changeable by experienced players to the correct German language graphics, as it's a real immersion killer, if you'll pardon the phrase.
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Old 11-30-2019, 10:22 PM   #2
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+1

They don't loiter/pursue for nearly long enough.
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Old 12-02-2019, 05:42 AM   #3
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I think this is so for gameplay purposes. If escorts prosecuted their searches much longer, as they did historically, we'd be looking at multiple hours spent under after being detected. In most cases, this would simply cause parties to give up and start a new lobby once detected, which is of course less than ideal because it removes a significant part of the U-boat experience.

Much like torpedoes that reload 10 times faster than in real life, the escort behavior too is altered to offer a form of "soft" time compression. Overall, this is a good thing for the type of game Wolfpack is. It can't be exactly like Silent Hunter because it's multiplayer, real time, has no save system etc.

Ironically, more realism doesn't always mean more fun, although too little realism is a turnoff. Maybe we need realism settings per lobby. Oh, that reminds me:
https://steamcommunity.com/sharedfil...?id=1695740380
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Old 12-02-2019, 09:01 AM   #4
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Your point about "soft time compression" is well made, however, in my limited experience one seems generally limited to 2 firing passes by an escort. I'm suggesting it should be 5-10 or so, not hours upon hours. As it stands, the period of being hunted is so short it doesn't even affect battery or air-use unduly, and damage beyond loss of light-bulbs is non-existant assuming no near direct-hit.

I can see an argument exists for not introducing longer searches/attacks until a the damage/repair model has more fidelity, as suffering a longer dc attack without more incremental and varied damage to sort out would be poor.
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Old 12-03-2019, 03:55 AM   #5
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Ah, I see. Slightly longer and more persistent depth charging does sound like a good idea.
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Old 12-04-2019, 11:30 AM   #6
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I was thinking in the order of 15-25 minutes of active hunt/depth-charging. However, as many of you know, the disturbed water from depth-charges made re-acquiring the U-boat very difficult. I do not know what the interval between successful asdic searches was, although I surmise that once most of the bubbles created had reached the surface, this would likely define the earliest point in time where a successful asdic detection could re-occur.

This suggests that the interval above would be proportionate to the depth at which the charges exploded, assuming a steady acceleration of, and constant size of, the bubbles returning to the surface.

This also touches on an as yet unmodeled effect of depth-charges: If charges exploded below the depth of the U-boat, then the effect was to temporarily rob the U-boat of buoyancy, causing it to sink rapidly at least to the level at which the charges detonated. This in turn compels the U-boat crew to have to make more strenuous efforts to attain and maintain depth expending air, or making noise via e-motor derived dynamic buoyancy. In my view this would be a most worthy aspect of boat physics to model.
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Old 12-04-2019, 11:19 PM   #7
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Evidently explosions above the boat would also push it down fairly dramatically. I recall reading a first-hand account of an accidental dive below 200 m due to this effect.
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Old 12-05-2019, 12:10 PM   #8
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Interesting, I'd have expected a movement upwards resultant from dc's exploding above, as the aerated water above would be significantly less dense that than the column of water existing previous to detonation: thus causing an uncontrolled rise until the U-boat has exited the area of disturbed water.

Self-evidently a very close near-miss above might cause a momentary descent, however, I'd expect the overall effect to be a rise. It may be the case that damage or deformation to the 'planes caused the dive, rather than changes in density of the water?

What I think is desirable here, is that being under dc attack can involve sudden changes to buoyancy and extra air expended and/or coarse plane movements to try and bring the boat back into a level pitch angle, and back into trim. Failure to do so resulting in either a descent below crush-depth, or below the depth at which tanks can be blown to affect static buoyancy and correct depth, leading to the need to use (noisy) e-motor power settings and dynamic buoyancy to restore control. Or indeed being forced to the surface, arguably the primary aim of depth charge attacks.
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Old 12-05-2019, 01:03 PM   #9
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Default I want wolfpac + that what shIII gwx ofers...

I know it is a thread about AI only, but i have plenty remarks about these future amazing game, so here you go:

1. AI – in simple words they're too easy. DD sensors are good modelled, but AI is way to easy, to passive and to predictible (especially at hard level – it is not hard at all easy). It misses a “Human” factor. Escort vessels shall in no circumstances sail with constant heading. Shaips had eaven an automatic mechanism altering their HDG in some pre-programmed shema. A typical behave shall look like these:
- A ZIG – ZAG phase with greather speed than the convoy does, 10-13kts with ASDIC turned on. (Above 13 kts speed ASDIC doesn’t work)
- A “Full stop phase” a boat is listening on Hydrophone. U-boat making too much noise on surface schould be detected.
- Speed up to cath “default” position I convoy screen.
- ASDIC shall be constantly turned on (except of “listening” phase)
2. Night fight.
- A muzzle flash of U-Boat gun shall trigger immediate salvo of flares,
- Shortly after detecting a U-Boat (if he’s highlighted by flares) Escort shall do a RAPID FIRE of everytching what’s on a escort vessel. Naval artilery, AAA artilery, Heavy machine guns.
- Vessel comunicates U-Boat position to other escort vessels. Especially the one sailing behind a convoy – a killer shall came to help.
- Escort closes distance rapidly NOT IN A STRAIGHT LINE!
- Surface ship is usually more stabile gun platform, has better (bigger) distance measure devices. Fire accuracy of 100-150mm shall become better with every salvo. A trained DD or Sloop crew shall get correct distance to the target not later than after 3’rd salvo.
3. U-boat on periscope depth (except of shallow water) shall be easy and clearly detected by ASDIC. Escort should be as aggressive as it’s possible in these case. Ramming, shooting to periscope if it’s spotted in a searchlight.
4. Escort shall use a torpedo trace to find a U-Boat:
- If torpedo is detected: U boat is probably 800 – 1500m from her target somwhere on the track left by torpedo
- If only a hit is detected - Escort runns at greatest speed to the most possible fire position: about 800m from ship targeted by U-Boat, on 90° AOB
5. U-Boat behave under water.
- Trim is a grat idea, but balance tanks are still under development? Right? There are two of them. One at the Bow one at the Stern.
- Leckage. They mostly happen at 12-30 m. Deeper pressure “seals” all the boat (if It’s not damaged). The only exception is a exhaust pipes Valves. They’re opening “inside” not “outside”, so they’re closed by heavy lock mechanism and they’re not sealed by the preasure. Every DC affecting a U-Boat shall trigger a quick, temporary leackage (usually response of the crew is quick since is a known weak spot).
6. How about introducing a Doppler effect on hydrophone? (Finally!!!!). Right from the beginning It’s the easiest known way to estimate if contact is closing the distance or moves away.

Last edited by Kermit the Frog; 12-05-2019 at 02:02 PM.
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Old 12-05-2019, 02:20 PM   #10
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I fully agree with you about the escort AI badly needing a major overhaul. As it stands, the AI escorts are so predicatable, in so many ways that insertion of a u-boat into a firing area is endlessly repeatable in more or less complete certainty one won't be detected or otherwise inconvenienced by an escort doing the unexpected.

Personally I can't wait for playable escorts, and the ability of the captains thereof to take unpredictable decisions. It'll make for a much tenser gamer for all concerned. I'd also like to see the possible formation of hunter-killer groups as an adjunct to normal escorts circa '43 onwards.

Another area that requires a lot of development is the damage model to various classes of merchants, in particular the notion that 1 torpedo hit auto-magically results in any given ship sinking within minutes. A more nuanced damage model where crippled ships fall out of the convoy screen, and require further torpedoes or deck-gun action would be a lot better, and more torpedoes being required for the larger ships (as a generalisation) better still.


Quote:
Originally Posted by Kermit the Frog View Post
I know it is a thread about AI only, but i have plenty remarks about these future amazing game, so here you go:

1. AI – in simple words they're too easy. DD sensors are good modelled, but AI is way to easy, to passive and to predictible (especially at hard level – it is not hard at all easy). It misses a “Human” factor. Escort vessels shall in no circumstances sail with constant heading. Shaips had eaven an automatic mechanism altering their HDG in some pre-programmed shema. A typical behave shall look like these:
- A ZIG – ZAG phase with greather speed than the convoy does, 10-13kts with ASDIC turned on. (Above 13 kts speed ASDIC doesn’t work)
- A “Full stop phase” a boat is listening on Hydrophone. U-boat making too much noise on surface schould be detected.
- Speed up to cath “default” position I convoy screen.
- ASDIC shall be constantly turned on (except of “listening” phase)
2. Night fight.
- A muzzle flash of U-Boat gun shall trigger immediate salvo of flares,
- Shortly after detecting a U-Boat (if he’s highlighted by flares) Escort shall do a RAPID FIRE of everytching what’s on a escort vessel. Naval artilery, AAA artilery, Heavy machine guns.
- Vessel comunicates U-Boat position to other escort vessels. Especially the one sailing behind a convoy – a killer shall came to help.
- Escort closes distance rapidly NOT IN A STRAIGHT LINE!
- Surface ship is usually more stabile gun platform, has better (bigger) distance measure devices. Fire accuracy of 100-150mm shall become better with every salvo. A trained DD or Sloop crew shall get correct distance to the target not later than after 3’rd salvo.
3. U-boat on periscope depth (except of shallow water) shall be easy and clearly detected by ASDIC. Escort should be as aggressive as it’s possible in these case. Ramming, shooting to periscope if it’s spotted in a searchlight.
4. Escort shall use a torpedo trace to find a U-Boat:
- If torpedo is detected: U boat is probably 800 – 1500m from her target somwhere on the track left by torpedo
- If only a hit is detected - Escort runns at greatest speed to the most possible fire position: about 800m from ship targeted by U-Boat, on 90° AOB
5. U-Boat behave under water.
- Trim is a grat idea, but balance tanks are still under development? Right? There are two of them. One at the Bow one at the Stern.
- Leckage. They mostly happen at 12-30 m. Deeper pressure “seals” all the boat (if It’s not damaged). The only exception is a exhaust pipes Valves. They’re opening “inside” not “outside”, so they’re closed by heavy lock mechanism and they’re not sealed by the preasure. Every DC affecting a U-Boat shall trigger a quick, temporary leackage (usually response of the crew is quick since is a known weak spot).
6. How about introducing a Doppler effect on hydrophone? (Finally!!!!). Right from the beginning It’s the easiest known way to estimate if contact is closing the distance or moves away.
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Old 12-06-2019, 01:10 AM   #11
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Quote:
Originally Posted by Fidd View Post
Interesting, I'd have expected a movement upwards resultant from dc's exploding above, as the aerated water above would be significantly less dense that than the column of water existing previous to detonation: thus causing an uncontrolled rise until the U-boat has exited the area of disturbed water.
I'm no physicist, but my understanding is that while you are correct about the boat diving through the less dense aerated water after an explosion below it, the effects of an explosion above the boat have less to do with aeration and more with displacement.

Let's consider what happens when a depth charge explodes above a U-boat, in phases:

1. The explosion causes a rapid expansion of air away from the epicenter. Water is an incompressible fluid, meaning that the water displaced by the explosion will initially push outward, including downward against the U-boat, causing it to descend.

2. The air bubble collapses, causing an inrush of water into it. At any significant depth, gravity will ensure that most of the water displacing the air will come from above, creating a weaker secondary shockwave as it plunges towards the epicenter of the explosion and then below it under its own inertia, colliding with a weaker upward current from the water below doing the same thing. The U-boat below is likely experiencing it as a further downward push (and a good shake) a second or so after the initial one.

3. If the U-boat is running at speed (not inconceivable under the circumstances) and the explosion was forward of center-mass, the bow is now angled further down than it likely already was.

All these factors put together - I think - may cause an uncontrollable dive that is difficult to arrest because the dive planes lose effectiveness at high speed and downward angle much for the same reason that it is difficult for a plane to pull out of a nosedive.
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Old 12-06-2019, 10:26 AM   #12
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Ok, I completely buy that as an explanation which squares anecdotal evidence (accounts) with some sound physics.

Out of curiosity, does anyone know the time intervals at different depths, for the main ballast tanks to be blown or flooded?

The reason I ask is that again working from anecdotal accounts, a loss of vertical control was not that unusual, with u-boats being "blown to the surface". This suggests that in attempting to recover from great depths, the main ballast tanks were blown at least partially, but that reflooding them either not be achieved quickly enough to prevent broaching to the surface, or, that once a rapid upwards movement began, it could not be arrested despite the main ballasts being reflooded at depth.

I suspect the latter, which might indicate that the inertia of our boats is a little off, as in the ordinary way we can always (air permitting) blow the mains at depth and arrest that ascent before broaching...

It might also mean that our planes are rather too "fast-acting" in altering the pitch of the boat?
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Old 12-06-2019, 11:27 AM   #13
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Quote:
Originally Posted by Fidd View Post
The reason I ask is that again working from anecdotal accounts, a loss of vertical control was not that unusual, with u-boats being "blown to the surface". This suggests that in attempting to recover from great depths, the main ballast tanks were blown at least partially, but that reflooding them either not be achieved quickly enough to prevent broaching to the surface, or, that once a rapid upwards movement began, it could not be arrested despite the main ballasts being reflooded at depth.
True

Whole mechanism workes like these: Let's say that you pumped out 5 tons of water from forward and 5t from aft tanks at 180m depth. Your boat is slowly rising. The more you go up the smaller pressure of water around you. At 90m depth there's 10 t of water less in your tanks - air inside the tanks expands. at 45m there's allready 20 t of water pumped out. The shalower you are the faster you're surfacing. It works in game, except one thing.

the "negative tanks" is placed inside the pressure hull. The other 4 are not. They're not pressure - resist. That means, if you blown your balast at 200m depth you have to keep inside and outside pressure at the same level. If they're full of air it must stay like these till surface. Otherwise if you open valves at let's say 100m the water surrounding will crusch them. It worked like these in real U-Boat. I am not sure about the game
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Old 12-06-2019, 11:47 AM   #14
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That doesn't quite make sense to me yet. If you've blown the main ballast tanks (hence-forwards MBT's) at 200m, then the air pressure inside is circa 20 atmosphere's, however, by the time you reach the surface you've still got 20 bar in the MBT's, but nil outside water pressure.

So unless you've vented that high-pressure air in the MBT's during the ascent, you've now an air-pressure being exerted on the inside of the MBT's of 19 bar, or 266lbs per square inch.

That's an awful lot! So either the MBT's were resistive to pressures of that order, or, there was a means to relieve climbing air-pressure within the MBT's as the U-boat ascended?
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Old 12-06-2019, 11:55 AM   #15
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Quote:
Originally Posted by Fidd View Post
That doesn't quite make sense to me yet. If you've blown the main ballast tanks (hence-forwards MBT's) at 200m, then the air pressure inside is circa 20 atmosphere's, however, by the time you reach the surface you've still got 20 bar in the MBT's, but nil outside water pressure.

So unless you've vented that high-pressure air in the MBT's during the ascent, you've now an air-pressure being exerted on the inside of the MBT's of 19 bar, or 266lbs per square inch.

That's an awful lot! So either the MBT's were resistive to pressures of that order, or, there was a means to relieve climbing air-pressure within the MBT's as the U-boat ascended?
Main Balast tank works different - it is pressure tight. other tanks are not. If pressure around tanks drops down - air inside expands and water from the tanks is "pushed out"

To be correct: Main Balast Tank (the Negative) is placed inside the pressure hull. The forward and aft balast tanks are placed outside of the hull. As far as i know they were constatntly opened from below. That is why you just need to open top vents to dive the submarine. To survive U-Boat need only MBT. All external balast tanks can be destroyed and u-boat is still abble to float.

Last edited by Kermit the Frog; 12-07-2019 at 04:36 AM.
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