Submarine water dynamics

[JeromeHeretic]

Originally Posted by Dirk Gently

The player sub doesn't run in convoys though...

Sure... but i wrote it as an example of problems with only a bit changed values. I don't remember all problems i had, it's years ago.
I think in some supermod authors was playing with this parameters once (in LSH maybe?) and after this tuning sub was almost uncontrollable. Was almost impossible drive out from docks without crash and so...

[ETR3(SS)]

Playing with settings and observing the results. I'm playing with the aircraft in SH4 with the intent of making them historically accurate at the moment. You get some interesting results sometimes, like the H6K getting below its flight path and pulling straight up to get back to altitude. Aircraft stalls and plummets back into the ocean.

[Dirk Gently]

I actually achieved more success than I hoped for.

What mainly did the trick was to increase Surface Up and Down drag to between 0,3 and 0,4 and place the ballast weight (balance point) slightly lower than Ubisoft has done, which is smack in the middle of the geometrical shape, and at the same time keeping the fore and aft balance intact to keep the vessel balanced. Submerged UD-drag remained as default to not mess with the most important part of the game, and that works out very well because the subs now behave like they actually want to stay afloat and at the same time look like they weight many tons, which they do.

While I was in there I also tweaked Mass, surface displacement and submerged displacement to historical metric ton values and tweaked diesel range and electrical range to historical values as well.

If there's any interest I could probably pack it as a mod file but if there's a lot of mod compatibility issues I'd rather write a tutorial.

[Niume]

Originally Posted by Dirk Gently

I actually achieved more success than I hoped for.

What mainly did the trick was to increase Surface Up and Down drag to between 0,3 and 0,4 and place the ballast weight (balance point) slightly lower than Ubisoft has done, which is smack in the middle of the geometrical shape, and at the same time keeping the fore and aft balance intact to keep the vessel balanced. Submerged UD-drag remained as default to not mess with the most important part of the game, and that works out very well because the subs now behave like they actually want to stay afloat and at the same time look like they weight many tons, which they do.

While I was in there I also tweaked Mass, surface displacement and submerged displacement to historical metric ton values and tweaked diesel range and electrical range to historical values as well.

If there's any interest I could probably pack it as a mod file but if there's a lot of mod compatibility issues I'd rather write a tutorial.

please do it.

[Dirk Gently]

This is an obsession, really.

I found a real VII manual online and found the exact Gravity Centre of the ballast on a drawing. A quick X-formula could translate the drawing to real world measurement, which turned out to be 2,796m from the bottom of the keel.

This actually messed up my previous tweaks a bit but the first tests of a "new" tweak is really promising. I've managed to get the sub to keep periscope depth at 1 knot and stationary and at the same time having waves influencing the stability of the periscope realistically.

Since there's no real physics involved in acceleration of the submarines from the propellers at the aft, the bow won't naturally rise from acceleration like in real life, so the aft is unnaturally popping up and the mid section becomes too high in the water as a result.

Due to these limitations the best I can achieve is to make the subs appear to actually have weight and avoid these awkward 10 meter dives in bad weather while maintaining the maneuverability of the sub. The main feature of this last discovery is that the side-rolling becomes much more realistic with the G point placed more or less spot on where it actually was. Pushing down the stern is not achievable without making the sub dive awkwardly and become unbalanced while submerged, sadly.

I'll post an update later tonight or tomorrow.

PS. I'm a math teacher so I trust my calculations but if anyone is curious I can upload a screenshot with measurements and calculations.

PPS. I'm also aware that realistic weight and measurements won't translate realistically into a body of water that isn't behaving 100% realistically but as long as it gets better than the starting point, and I'm enjoying the work, I'm going for it.

[JeromeHeretic]

Do both. Mod for people which will like it (or just want try it and when will like it, merge it to their mods) and do manual, so people can easy implement it into their work.

[Dirk Gently]

Use this thread for any further communication and feedback regarding this mod; http://subsim.com/radioroom/showthread.php?t=239358

Proof of concept mod.

This is only the VIIB as it's the only Sub I've fully tested so far.

All weights and displacement changed from Long Tons to US tons assuming that's what the game uses since it also seem to be using US miles for range.

I'll explain in further details exactly what the final tweaks are and I'd appreciate feedback on this one. During testing the boat never went below 6 meters in bad weather. It cuts through some waves while riding others, depending on whether she's rising or falling when she hits the wave. I managed to keep the stern lower than default and make the bow rise to keep the boat afloat rather than going for those infamous 10m dives with crew on deck. You'll rarely see the propellers out of the water.

It's worth noting that I've only tested the mod with MEPv6 installed, which I believe affects waves somewhat.

Warning: The mod only affects a tiny .sim file in the VIIB Submarine directory

DOWNLOAD v0.1