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-   -   SH3's flawed sub physics?[A request] (https://www.subsim.com/radioroom/showthread.php?t=126278)

Castout 12-14-07 01:33 AM
so even WWII sub was not a real submersible craft in the sense that they need to have a forward motion in order to maintain depth?

When I see Das boot or U-571 I think I saw them at 0 knots at periscope depth in those movies.

Ouch linerkiller got me first...

So the pump must work in order to maintain depth? So in theory in silent running wheere the pumps are being turned off the boat would keep on sinking with no forward motion.

PhantomLord 12-14-07 04:59 AM
Quote:
Originally Posted by Castout
so even WWII sub was not a real submersible craft in the sense that they need to have a forward motion in order to maintain depth?

When I see Das boot or U-571 I think I saw them at 0 knots at periscope depth in those movies.

Ouch linerkiller got me first...

So the pump must work in order to maintain depth? So in theory in silent running wheere the pumps are being turned off the boat would keep on sinking with no forward motion.
Movies will be movies, will be movies... :D

In RL subs need some forward motion.

"Das Boot" the book describes some techniques to "hang up the boat on the periscope". This is possible without engines running only at absolutly calm sea. You can have some hover effect with endless fine trimming. All has to do with the relation of water pressure outside and water displacement of the boat. You really need the pumps for that. So it´s no option in silent running...

You´ll need an extra physic´s engine for SH3 to simulate all that tiny stuff that really happens in a such complex vehicle like an u-boat. An definitly more men to handle this. Hey that would be a nice idea for MP? Everyone has his station in only ONE boat....

In one of my books (i think it was "Wolfgang Hirschfeld - Feindfahrten / Diary of an u-boat-radio-operator") he talk about another boat that sinks slowly down while submerged at low speed. The crew forgot to open a valve for the depth meter in the command room. So everyone thought they still were at 80 meters. In real the boat was near 220 meters at this time. One man noticed that at his sister instrument in the engine room... i think he got an extra bottle of beer later :D

von Zelda 12-14-07 07:08 AM
First patrol with GWX 2.0 in a Type II
 
I've found that at 2 knots there is a slight positive bouyancy (approximately 2 meters at periscope depth). So, to maintain periscope depth of 12 to 13 meters, I need to set depth at 14 to 16 meters; otherwise conning tower begins to break the surface.

Is this correct or to be expected in 2.0?

linerkiller 12-14-07 07:17 AM
Quote:
Originally Posted by PhantomLord
Quote:
Originally Posted by Castout
so even WWII sub was not a real submersible craft in the sense that they need to have a forward motion in order to maintain depth?

When I see Das boot or U-571 I think I saw them at 0 knots at periscope depth in those movies.

Ouch linerkiller got me first...

So the pump must work in order to maintain depth? So in theory in silent running wheere the pumps are being turned off the boat would keep on sinking with no forward motion.
Movies will be movies, will be movies... :D

In RL subs need some forward motion.

"Das Boot" the book describes some techniques to "hang up the boat on the periscope". This is possible without engines running only at absolutly calm sea. You can have some hover effect with endless fine trimming. All has to do with the relation of water pressure outside and water displacement of the boat. You really need the pumps for that. So it´s no option in silent running...

You´ll need an extra physic´s engine for SH3 to simulate all that tiny stuff that really happens in a such complex vehicle like an u-boat. An definitly more men to handle this. Hey that would be a nice idea for MP? Everyone has his station in only ONE boat....

In one of my books (i think it was "Wolfgang Hirschfeld - Feindfahrten / Diary of an u-boat-radio-operator") he talk about another boat that sinks slowly down while submerged at low speed. The crew forgot to open a valve for the depth meter in the command room. So everyone thought they still were at 80 meters. In real the boat was near 220 meters at this time. One man noticed that at his sister instrument in the engine room... i think he got an extra bottle of beer later :D
And every day the leitender ingenieur had to mesure the water density ( seawater density change from place to place) and correct the boat's trim ....because in a 750-ton VIIC, also a 1/1000 error led to a notable 750 kg error, and during a crash dive this could be fatal.
To connect the previous topic, Buccheim wrote that during the depth-charge attack the commander ordered the pumps on during the explosion, to avoid detection.....RL is HARD:arrgh!:

Castout 12-14-07 10:55 AM
Okay okay I got the picture. RL depth control in U-boat is shi*ty hard.

Sailor Steve 12-14-07 12:17 PM
Quote:
Originally Posted by von Zelda
I've found that at 2 knots there is a slight positive bouyancy (approximately 2 meters at periscope depth). So, to maintain periscope depth of 12 to 13 meters, I need to set depth at 14 to 16 meters; otherwise conning tower begins to break the surface.

Is this correct or to be expected in 2.0?
The last GWX had the positive bouyancy thing. Most people complained that they didn't like it, so they created a fix you could download. I complained that I thought it was a good idea, but with only a 2-meter change it was too easy to counteract. You should keep on rising until you sped up to counter it.

Anyway, the answer is yes. GWX 2 does not have it. Read the link to the changes they made.

Kpt. Lehmann 12-14-07 12:25 PM
Quote:
Originally Posted by Sailor Steve
Quote:
Originally Posted by von Zelda
I've found that at 2 knots there is a slight positive bouyancy (approximately 2 meters at periscope depth). So, to maintain periscope depth of 12 to 13 meters, I need to set depth at 14 to 16 meters; otherwise conning tower begins to break the surface.

Is this correct or to be expected in 2.0?
The last GWX had the positive bouyancy thing. Most people complained that they didn't like it, so they created a fix you could download. I complained that I thought it was a good idea, but with only a 2-meter change it was too easy to counteract. You should keep on rising until you sped up to counter it.

Anyway, the answer is yes. GWX 2 does not have it. Read the link to the changes they made.
Right. What we all really need is "variable bouyancy" modelled into SH3... which we can't have. As modders, we can either set for positive, or negative bouyancy... or stay with neutral... but we have to choose.

THere is still some slight positive bouyancy in GWX 2.0, but not as much as before... It is pretty close to neutral now. The trick was to pull this off without losing the cool new surface physics of the U-boats in GWX. In stock they basically just plowed through the water like bricks.:doh: Now in GWX, they toss and roll more appropriately in the waves... and make ya seasick if you turn off the lights.:arrgh!:

von Zelda 12-14-07 12:27 PM
Quote:
Originally Posted by Sailor Steve
Quote:
Originally Posted by von Zelda
I've found that at 2 knots there is a slight positive bouyancy (approximately 2 meters at periscope depth). So, to maintain periscope depth of 12 to 13 meters, I need to set depth at 14 to 16 meters; otherwise conning tower begins to break the surface.

Is this correct or to be expected in 2.0?
The last GWX had the positive bouyancy thing. Most people complained that they didn't like it, so they created a fix you could download. I complained that I thought it was a good idea, but with only a 2-meter change it was too easy to counteract. You should keep on rising until you sped up to counter it.

Anyway, the answer is yes. GWX 2 does not have it. Read the link to the changes they made.

Is there a mod for GWX 2.0 to correct or reduce this slight positive bouyancy?

Kpt. Lehmann 12-14-07 12:31 PM
Quote:
Originally Posted by von Zelda
Quote:
Originally Posted by Sailor Steve
Quote:
Originally Posted by von Zelda
I've found that at 2 knots there is a slight positive bouyancy (approximately 2 meters at periscope depth). So, to maintain periscope depth of 12 to 13 meters, I need to set depth at 14 to 16 meters; otherwise conning tower begins to break the surface.

Is this correct or to be expected in 2.0?
The last GWX had the positive bouyancy thing. Most people complained that they didn't like it, so they created a fix you could download. I complained that I thought it was a good idea, but with only a 2-meter change it was too easy to counteract. You should keep on rising until you sped up to counter it.

Anyway, the answer is yes. GWX 2 does not have it. Read the link to the changes they made.

Is there a mod for GWX 2.0 to correct or reduce this slight positive bouyancy?
Read my previous post for the answer. We've already taken care of it... looks like we cross posted.

von Zelda 12-14-07 12:53 PM
Yes, Kpt., we cross posted.

The problem that I had with the original postive bouyancy was in deep dives at slow speeds. I'd have to request depths much deeper than that I wished for just to get the slow moving u-boat deep enough.

My first patrol with 2.0 was to AN81 in a Type II so I haven't had an oportunity to try a deep dive yet.

von Zelda 12-14-07 09:11 PM
Tried a deep dive at slow speed (2 knots) such as one would use to evade destroyers. There is still a good deal of positive bouyancy so that the u-boat never reaches the requested depth. Must request depth 25 - 50 meters below desired depth.

While it might not be realistic, is there a mod for 2.0 which will result in zero bouyancy like stock game?

As the Captain, I like to request a desired depth and get to that depth; less let the virtual LI figure out the bouyance problem and give me the requested depth.

Kpt. Lehmann 12-14-07 09:23 PM
Quote:
Originally Posted by von Zelda
Tried a deep dive at slow speed (2 knots) such as one would use to evade destroyers. There is still a good deal of positive bouyancy so that the u-boat never reaches the requested depth. Must request depth 25 - 50 meters below desired depth.

While it might not be realistic, is there a mod for 2.0 which will result in zero bouyancy like stock game?

As the Captain, I like to request a desired depth and get to that depth; less let the virtual LI figure out the bouyance problem and give me the requested depth.
Hmmm, that's really odd as that doesn't occur on my installation and was never reported to be a problem in several months of testing after the adjustment was fielded. I'm not sure what to say other than it appears to be related to your installation somehow. (I'm sure that's not what you wanted to hear.) However, in GWX 2.0 at 1.5 - 2.0 knots while submerged, I've been consistantly able to set any depth in any boat and be within three meters of any requested depth.

Technically, I suppose you could take the stock SH3 1.4b .sim files for the uboats and replace them that way to achieve the old completely neutral bouyancy, but you'd also lose other physics corrective measures relating to engines, fuel consumption, and battery life.

von Zelda 12-14-07 10:32 PM
Quote:
Originally Posted by Kpt. Lehmann
Quote:
Originally Posted by von Zelda
Tried a deep dive at slow speed (2 knots) such as one would use to evade destroyers. There is still a good deal of positive bouyancy so that the u-boat never reaches the requested depth. Must request depth 25 - 50 meters below desired depth.

While it might not be realistic, is there a mod for 2.0 which will result in zero bouyancy like stock game?

As the Captain, I like to request a desired depth and get to that depth; less let the virtual LI figure out the bouyance problem and give me the requested depth.
Hmmm, that's really odd as that doesn't occur on my installation and was never reported to be a problem in several months of testing after the adjustment was fielded.
I did not mention it, but I'm using a Type II at the moment. Maybe most of the testing was with Type VII's and IX's?

Went back to my current patrol, requested a dive to 163 meters; after approximately 40 minutes at 2 knots, I reached 129 meters which held pretty constant until I surfaced.

This doesn't affect game play too much anyway. Maybe real Commanders had the same problem with their crews?

Kpt. Lehmann 12-14-07 11:46 PM
Will keep an eye on the Type II.

Just as a developmental note here, regarding player U-boat physics... the lighter the boat, the harder it is to adjust. Boats with less mass react more sensitively than heavier ones. The Type II's were naturally the most difficult to work on.

That being said, with the Type II on the surface in a storm in GWX... HOLD ON TO YOUR COOKIES!!! That thing rocks and rolls!:arrgh!:


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