launch transients, torpedo sounds, and realism

[Keelbuster]

I'm sure this topic has been beaten to death over the years, but it still bugs me. I'm not sure what the advantage was of an electric torp over a steam torp in real life, because I imagine that a torpedo launch (and it's entire subsequent run) would be such a noisy event that escorts would most certainly hear it, and hence get a good bearing to the attacker from it. Like - in real life, at torpedo launch, I imagine that ships would start evasion right away following a 'Torpedo in the water' report. I wonder if there's some way to mod this into SH3??

[Madox58]

:hmm:

My first thought would be to tie in an invisible Bold with no effects
to the launch.

Anybody listening hears those.
:yep:

[Sailor Steve]

I've read Nicholas Monsarrat's works (The Cruel Sea, Monsarrat at Sea), as well as Donald MacIntyre's U-Boat Killer, and I don't recall either of them ever mentioning anything like that; and they were both escort captains during the war.

[Keelbuster]

I've read Nicholas Monsarrat's works (The Cruel Sea, Monsarrat at Sea), as well as Donald MacIntyre's U-Boat Killer, and I don't recall either of them ever mentioning anything like that; and they were both escort captains during the war.
Interesting...it seems strange though eh? Like - here you have these escorts, with a SO listening carefully to the nearby ocean, hoping to catch a sonar ranging ping or the sound of an engine on a bearing with no surface contact, and then you've got this sudden cacophony followed by a long, loud, torpedo run. In terms of sound contacts, you might as well just shout. Like - SO's on surface warships did say 'Torpedo in the Water!' in those days right?

[Madox58]

I don't think they had the ability to hear sounds as well as now days.
Now days, they can tell what ship it is (by name!)
and if it's running properly!!

Back then?
I doubt you'd hear the doors and launch over the convoy sounds themselves.

[Keelbuster]

:hmm:

My first thought would be to tie in an invisible Bold with no effects
to the launch.

Anybody listening hears those.
:yep:

I like the idea - that might serve the purpose. I mean, it's not like GWX 2.0 is not challenging enough, but I'm wondering about this aspect of uboat combat. If firing a torpedo really was a _loud_, salient, event, then it should have an impact on the behaviour of the defenders.

[Keelbuster]

I don't think they had the ability to hear sounds as well as now days.
Now days, they can tell what ship it is (by name!)
and if it's running properly!!

Back then?
I doubt you'd hear the doors and launch over the convoy sounds themselves.

Yea - my feeling is the same - the transients would probably be hard to detect. However, a torpedo screaming along at 40 kts - that should be a pretty distinct sound contact, no? I mean, in the game, we can hear it very clearly - should not they also?

[Platapus]

I guess the ships sound heads would have to be aimed directly at the torpedo in order to pick up the sounds. What would be the chance of that happening at precisely the same moment as the torpedo passing through the bearing?

I think it would be much easier spotting the steam torpedo path and from what I read even that was difficult except in calm seas.

I think it would be a pretty lucky sound crew to detect a torpedo in WWII and to be able to locate and determine a reciprocal plot in time to take any effective maneuvers would be extra tough.

Has anyone come across any references from British or American ASW folks in WWII addressing this?

[Keelbuster]

I guess the ships sound heads would have to be aimed directly at the torpedo in order to pick up the sounds. What would be the chance of that happening at precisely the same moment as the torpedo passing through the bearing?

I think it would be much easier spotting the steam torpedo path and from what I read even that was difficult except in calm seas.

I think it would be a pretty lucky sound crew to detect a torpedo in WWII and to be able to locate and determine a reciprocal plot in time to take any effective maneuvers would be extra tough.

Has anyone come across any references from British or American ASW folks in WWII addressing this?
Yea - you'd be lucky to catch the transients. However, having 7-10 escorts per convoy tends to make you lucky. But once a torpedo is running, it's crazy to think that one of the escorts' SO wouldn't pick it up. As for specific plotting, like, i imagine that it would be hard to do because torpedoes move fast/flip across bearings. But at least you could get a crude guess about the position of the sub - and at the very least, you'd be able to initiate evasive maneuvers - snaking, etc, and potentially save ships.

[Brag]

With the WWII technology your hydrophones would have to be pointing at the U-boat to hear the launch. The sound man would need to be trained to interpret the sound.

The sight of the wake of the steamers allowed a warship to turn and avoid the incoming "kiss."

Nevertheless, on stock and GWX, the escorts will head for datum point (the location you launched your torpedoes from).

Thus, a small suggestion: get away from datum, do the wiggle-waggle and dive deep after launching. :|\\

[Albrecht Von Hesse]

Actually escorts could hear the torpedoes as they made their runs in.

During a U-Boat torpedo attack a sonarman picked up the distinctive hiss of an approaching fish. "I ran out on the bridge to prepare for an explosion. I looked over the side in time to see the torpedo streak on by about 10 feet away from the hull! An order had been given to stream FXR, and sure enough the torpedo headed for it and blew up well astern!"
Rocky Schoenrock, Sonarman, USS Inch (DE-146)
(http://www.de220.com/Armament/Decoys/Decoys.htm)


The biggest advantage is that electrics did not leave a visible bubble trail on the surface. That was visible for quite a distance in good visibility. And while merchants didn't have personnel manning hydrophones, they did have watch crews. If they spotted the bubble trail they could immediately detect not only where the torpedo had come from but, more importantly, where it was headed. Sometimes even a minute's warning was enough to initiate a course change sufficient to generate a miss. As well, electrics left no 'back-trail' for an escort to follow and trace.

[Madox58]

The problem with the Bold attach is,
There is no control over angle.
It's all or nothing.

A ship inline with a torp probably would not hear it because the
torp itself would block the sound,
and since the sound starts at the rear?
We have a cone of silence, so to speak.

[Keelbuster]

Thing is, a sonar ping is a transient, directional thing right? Allied soundmen could hear it if the sub made a ranging ping (I assume). I guess in the end though, this is probably a hard-coded thing in SH3 - either they hear torps or they don't. And they don't. I guess if you emitted a sonar ping at the time of launch, that could count as a 'launch transient'. Emitting a bold isn't quite right because it remains for a long time. Now, if there was some way to tie the 'invisible' bold device to the torpedo, so it followed it's course, then you might have an 'audible' torpedo from the AI's point of view. Problem is, from my experience, the bold device is _loud_ for the SH3 AI - I've accidentally dropped them when trying to set rudder to amidships, and the escorts come racing from miles away. And, then you'd get the AI chasing your torpedo...:)

In the late war, I'm firing pattern running torps from like 5km away. They have a few minutes of run-time, and the escort screen forms a rough circle around the convoy. You'd think they'd be monitoring the bearings outside of the convoy, and hence would detect a rather loud, angry, torpedo approaching before they could see the steam trail. Maybe not though. In modern warfare (c.f., dangerous waters), when you launch a torp, everybody knows about it.

[Amiral Crapaud]

Thing is, a sonar ping is a transient, directional thing right? Allied soundmen could hear it if the sub made a ranging ping (I assume).
Hum there was nothing such as an active sonar/ranging ping available on a U-Boot, maybe except for a very few number of them who may have been fitted with some active equipment... right?
I guess the presence of such gear in SH3 is somewhat fictionnal (the same with the ingame early availability of the type XXI boats).

But in the eventuality such equipement was available, yes technically speaking a ping would be heard by anyone in range with hydrophones, or even without them.

when you launch a torp, everybody knows about it. Yep, but Dangerous Waters/Contemporary sonar assets are omnidirectionnal, while a lot of WW2 hydrophones were often directionnal (aka you have to turn the wheel/the switch to listen in a given direction) (btw please tell me if Im wrong...). I suppose anyway that monitoring primitive omni-directional equipement, such as the first sonoboys, must have been quite a pain in the **s without an electric screen...

[Umfuld]

while merchants didn't have personnel manning hydrophones, they did have watch crews

Exactly


I like steam over electric. And it's rare that the bubble trail is detected and allows the merchant to evade. But it does happen.

[Keelbuster]

Thing is, a sonar ping is a transient, directional thing right? Allied soundmen could hear it if the sub made a ranging ping (I assume).
Hum there was nothing such as an active sonar/ranging ping available on a U-Boot, maybe except for a very few number of them who may have been fitted with some active equipment... right?
I guess the presence of such gear in SH3 is somewhat fictionnal (the same with the ingame early availability of the type XXI boats).

But in the eventuality such equipement was available, yes technically speaking a ping would be heard by anyone in range with hydrophones, or even without them.

when you launch a torp, everybody knows about it. Yep, but Dangerous Waters/Contemporary sonar assets are omnidirectionnal, while a lot of WW2 hydrophones were often directionnal (aka you have to turn the wheel/the switch to listen in a given direction) (btw please tell me if Im wrong...). I suppose anyway that monitoring primitive omni-directional equipement, such as the first sonoboys, must have been quite a pain in the **s without an electric screen...

I guess I'm just wondering - if you can't detect a launched/running torpedo with passive sonar, what are your chances of detecting a sub set for silent running on passive sonar? In game, if an escort comes close enough to you, it will detect you on passive sonar. However, if you fire an electric torpedo, even right beside an escort, unless the torpedo hits something, it's as if it was never there. I've taken long shots with T2s, and had them drift on through the convoy and out the other side. It's as if nothing happened - the escorts are oblivious to it. In real life I imagine that one of the 8 or 9 escorts would happen to pass his hydrophone over a bearing with a torpedo in it, and would recognize it. If you can't hear a torpedo, how are you going to hear a sub....

[Amiral Crapaud]

I guess I'm just wondering - if you can't detect a launched/running torpedo with passive sonar, what are your chances of detecting a sub set for silent running on passive sonar? In game, if an escort comes close enough to you, it will detect you on passive sonar. However, if you fire an electric torpedo, even right beside an escort, unless the torpedo hits something, it's as if it was never there.

That's a good point!

[Subnuts]

I'm sure this topic has been beaten to death over the years, but it still bugs me. I'm not sure what the advantage was of an electric torp over a steam torp in real life, because I imagine that a torpedo launch (and it's entire subsequent run) would be such a noisy event that escorts would most certainly hear it, and hence get a good bearing to the attacker from it. Like - in real life, at torpedo launch, I imagine that ships would start evasion right away following a 'Torpedo in the water' report. I wonder if there's some way to mod this into SH3??

During the Second World War, escort sonar could only hear down a narrow cone, normally about ten degrees across. The operator could rotate the sonar apparatus to listen in different directions, but he couldn't listen to the entire ocean at once. This isn't the case now, since modern sonars use hundreds of fixed hydrophones in large arrays, and display screens can depict incoming data in realtime, but in WWII, this limitation was a huge issue.

The main advantage of an electric torpedo is that they didn't leave a foamy wake which basically said "go down the bearing this wake and you'll find me soon enough!"