[tec] "bouyancy problem"

[Kromus]

Originally Posted by vickers03

this defines the wave influence on all surface vessels

Ok I give it a shot

[Ducimus]

Originally Posted by Kromus

Ok I give it a shot

Don't be surprised if you end up with some ahh..... side effects. Tuggin on those variables will fix sub on rails for sure, but it's much akin to being a kitten tuggin on a ball of yarn. Two biggest side effects to look out for is

- AI visual sensors changing drastically one way or another.
- surface ships randomly sinking/exploding for no apparent reason. (crash depth issue with damage zones in zones.cfg if i remember correctly)

To minimize the chance of that happening, Be gentle, don't adjust it drastically. Only as needed, and very carefully, and deliberatly.

[Kromus]

Originally Posted by Ducimus

Don't be surprised if you end up with some ahh..... side effects. Tuggin on those variables will fix sub on rails for sure, but it's much akin to being a kitten tuggin on a ball of yarn. Two biggest side effects to look out for is

- AI visual sensors changing drastically one way or another.
- surface ships randomly sinking/exploding for no apparent reason. (crash depth issue with damage zones in zones.cfg if i remember correctly)

To minimize the chance of that happening, Be gentle, don't adjust it drastically. Only as needed, and very carefully, and deliberatly.

Thx for warning and info

Yes I just tried changing original values (0.3->0.03 and 0.75->0.6) and sub was like "running through the waves" no pitch/roll anything. So definately this is the way so thx both for this. Problem seems to be those side effects now

[Ducimus]

>>no pitch/roll anything.

CG_Height in the sub's sim file. Default is 1. In previous games this was a little under or a little over 2. Here you have to be careful again or you'll have a sub doing 360's along its long axis, or end up upside down if rammed or something. One additional thing i noticed was that on deck, in rough weather and this adjusted to say 2.X.. i found myself catapuled onto the UZO as if i was standing on it. My "feet" being launched right off the conning tower deck. So, again, adjust carefully. Hope you like restarting the game alot. (insert DRM rant here).

With stock enviormental settings and waves, i found ehh 1.8 or 1.9 (i forget, but i think 1.8) to be the most i could set it before having the "catapult onto the UZO" feeling.

Hmmm.. i guess the camera doesn't move with the boat?

[vickers03]

Originally Posted by Kromus

Yes I just tried changing original values (0.3->0.03 and 0.75->0.6)

sorry but you're not looking carefully enough,
it should be 0.3->0.6 and 0.75->0.03, a big difference.

here's my modded 7a, take a close look at ALL values
and compare with sh3/GWX stuff.
http://www.filefront.com/16047457/sh...sh5_7a_test.7z

[Kromus]

Originally Posted by vickers03

sorry but you're not looking carefully enough,
it should be 0.3->0.6 and 0.75->0.03, a big difference.

here's my modded 7a, take a close look at ALL values
and compare with sh3/GWX stuff.
http://www.filefront.com/16047457/sh...sh5_7a_test.7z

Yes I noticed that it did the opposite thing :P I`ll look at your file later gotta go sleep, gn.

Edit:

http://www.filefront.com/16048001/7b_test.zip

My try with VIIB but still with original values in sim.cfg used (will be messed up if sh3 sim.cfg values used)! Now for real, cya tomorow.

[Redlance88]

so we have some idea of what values can be adjusted, and it sounds like with the right "tweaking" of some of them we might be able to get a boat that will be able to maintain a depth at all stop but beyond that depth will need progressively more forward motion to not sink to oblivion. and to me that sounds correct in terms of real world physics. so now the question becomes what are accurate values for the historical subs, and at what depth did this become a factor if at all. if that depth is beyond crush depth the point becomes moot. and nothing is needed beyond any adjustment to keep the effect from happening too soon( shallow). thoughts?

[Bilge_Rat]

just to add some real world data which may or may not have a bearing.

Normally, a submarine will trim to have a slightly positive buoyancy and will use a slight downward angle on the planes and forward motion to maintain a set depth. The theory being that if power should be lost for any reason, the sub will gently rise to the surface.

the trim for a boat is dynamic and directly influenced by the depth. Air provides buoyancy and its effect is influenced by depth. As you go deeper, air is compressed and loses its buoyancy. A boat which is positively buoyant at 50 meters will be negatively buoyant at 150 meters at the same trim since the air in the ballast tanks will be compressed letting in more water.

normally, when a boat dives from, say, 50 meters down to 150 meters, the diving officer will have to rest the trim by pumping additional air in the ballast tanks to again achieve a slight positive trim.

All these factors also explain why you sometimes hear stories about crews losing control of the depth. If the wrong buoyancy, plane angle, speed is set, the boat may easily go past the set depth before they are able to bring it back to an equilibrium.

Although in theory, it may be possible for a sub to maintain depth while motionless, it practice it would be too difficult.

of course, none of these factors have ever been properly represented in a subsim and they may not have a bearing on the discussion here.

[Redlance88]

Originally Posted by Bilge_Rat

just to add some real world data which may or may not have a bearing.

Normally, a submarine will trim to have a slightly positive buoyancy and will use a slight downward angle on the planes and forward motion to maintain a set depth. The theory being that if power should be lost for any reason, the sub will gently rise to the surface.

the trim for a boat is dynamic and directly influenced by the depth. Air provides buoyancy and its effect is influenced by depth. As you go deeper, air is compressed and loses its buoyancy. A boat which is positively buoyant at 50 meters will be negatively buoyant at 150 meters at the same trim since the air in the ballast tanks will be compressed letting in more water.

normally, when a boat dives from, say, 50 meters down to 150 meters, the diving officer will have to rest the trim by pumping additional air in the ballast tanks to again achieve a slight positive trim.

All these factors also explain why you sometimes hear stories about crews losing control of the depth. If the wrong buoyancy, plane angle, speed is set, the boat may easily go past the set depth before they are able to bring it back to an equilibrium.

Although in theory, it may be possible for a sub to maintain depth while motionless, it practice it would be too difficult.

of course, none of these factors have ever been properly represented in a subsim and they may not have a bearing on the discussion here.

actually this is exactly the sort of thing I am trying to get at. so as the creator of this thread it has a lot of bearing to the discussion I am trying to have. I am trying to figure out how well all of this can be incorporated into the game being as it seems that a lot of the foundation for it is in the code just a question of what is realistic and what is reasonable. I think it is fair to say that trimming a sub for a specific depth in wwII was more an art than a science. but need to keep the rest of the game playable too. so we can find out the rate of compression volume at specific depths, so we can relate that to the total max volume of the ballast tanks to determine at what point there isn't enough left to keep the sub from being negative buoyant ( I suspect that that total is beyond crush depth but perhaps not) and then figure out a rate for "up force /knot of speed" from the planes and the rest it just trying to make the values match the assumptions. I think we can do this....... so time to track down some volume of air per atmosphere of depth charts and displacement values for type VII subs also what is the max compressed air capasity of the sub at 100% being as that info is modeled in the game as well use up too much compressed air and ya can't surface. but ya might be able to maintaiin a depth till ya run out of fuel. ( that would suck. ) but in a morbid way be really cool.

[Hitman]

I understand it that at a depth below 250m or so it is very difficult to keep the sub from going to the bottom for good. Basically flank speed to maintain that depth or sink further and crush. My question is this, is this a bug or is this the way that they worked then. it's not as simple a question as it may seem. as a scuba diver, I know that near the surface one often has to add weight just to be able to stay underwater, but as you go deeper , you have to keep adding air to a Buoyancy control device to keep control of your depth and to keep from rapidly sinking. to me this sounds like the same thing is happening to the subs, and here is the kicker, after a certain depth there is no more volume for the trim tanks to keep the sub at the ordered depth , to to maintain depth you need up force from the dive plains. just like on the surface you need negative on the plains to force the sub underwater. ( I think ya can still dive a u-boat without them, but it would take a bit longer) the depths that this sort of effect would happen may be all wrong, but just thinking before it is (fixed) make sure it needs fixing.
I welcome comments from any more in the know than I.

What I can add is that because of the huge pressure over the steel, it is bounced inwards at great depths and as such the actual volume of the UBoat is decreased even more, making it heavier when compared to the water because it displaces less of it. I can't say how much this effect causes, but I know it exists. It might be neglectable or not, but it was known and mentioned in WW2 documents/books, though I can't right now tell from memory where I readed it