View Full Version : (REQ) Slower U-Boat Dive Times and more accurate handling
Has anyone addressed the U-boat's handling (turn rate, dive/surface rates, etc) espcially the dive times? It seems my ankles are getting wet before I've even taken my hand off the diving alarm...
"Clear the bridge! Dive, Di...(glub, glub, glub)"
Georg_Unterberg
03-14-08, 03:32 PM
yes, please Modders make a quick hotfix to set the dive times for the IX-D2 more realistic.
Even aircraft are no threat anymore, unless they are *very* close when spotted.
also the file "dive sequence.wav" isn't played anymore - maybe because the audio was still playing while you were on 70m depth already :lol:
Has anyone addressed the U-boat's handling (turn rate, dive/surface rates, etc) espcially the dive times? It seems my ankles are getting wet before I've even taken my hand off the diving alarm...
"Clear the bridge! Dive, Di...(glub, glub, glub)"
It's something we're looking into for RFB. Does anyone have any sources that say what the dive times were for the Type IXs? (I already have data for the XXI/XVIII).
Xantrokoles
03-14-08, 03:37 PM
I recognized the same thing and so I opened the [uboat].sim file (found in Data/Submarine/[uboat])with skwas Silent 3ditor (http://www.subsim.com/radioroom/showthread.php?t=119571&highlight=silent+3ditor)
then edit:
ManBT_flood_speed
(u find this in: 8:unit_submarine ->properties->ballast)
lower the value and save it
Xantrokoles
03-14-08, 03:41 PM
It's something we're looking into for RFB. Does anyone have any sources that say what the dive times were for the Type IXs? (I already have data for the XXI/XVIII).
They said the crash dive time is: 35sec
http://www.alphawolf1941.de/typ_ix.html
They said the crash dive time is: 35sec
http://www.alphawolf1941.de/typ_ix.html
Not for the IXD2. That page says it's 40 seconds.
Its been a while since i read iron coffins but he specifically discusses in several areas how hard they pushed to get the crash dive times down. This was also addressed in Thunder Below. If my memory serves me correctly i think the numbers that Capt. Werner cited were a little less than that of the US counter parts. Im on the road so i dont have the book handy but the Uboats dive time in that book was well under 25 seconds i think... i could be way off i have to look when i get home.
I felt like the crash dive times for the uboats were really fast but my hunch figured it was close to correct :hmm:
Its been a while since i read iron coffins but he specifically discusses in several areas how hard they pushed to get the crash dive times down. This was also addressed in Thunder Below. If my memory serves me correctly i think the numbers that Capt. Werner cited were a little less than that of the US counter parts. Im on the road so i dont have the book handy but the Uboats dive time in that book was well under 25 seconds i think... i could be way off i have to look when i get home.
Crash dive times for the VIIs were around that range, but the IXs were certainly slower than that. Seeing that number of 40 secs for the IXD2 sounds about right for a boat that big.
40 seconds leaves some time for a pucker factor! :o Like the fleet boats i would find myself thinking, 'come on already!':D
Xantrokoles
03-14-08, 04:13 PM
Its been a while since i read iron coffins but he specifically discusses in several areas how hard they pushed to get the crash dive times down. This was also addressed in Thunder Below. If my memory serves me correctly i think the numbers that Capt. Werner cited were a little less than that of the US counter parts. Im on the road so i dont have the book handy but the Uboats dive time in that book was well under 25 seconds i think... i could be way off i have to look when i get home.
Crash dive times for the VIIs were around that range, but the IXs were certainly slower than that. Seeing that number of 40 secs for the IXD2 sounds about right for a boat that big.
Dont't u think that a good crew could bring their sub in 30 seconds down?:hmm:
Dont't u think that a good crew could bring their sub in 30 seconds down?:hmm:
Sure they could, but what matters more in things like this is an average value, not what the most experienced, veteran crew could accomplish.
Xantrokoles
03-14-08, 04:24 PM
Sure they could, but what matters more in things like this is an average value, not what the most experienced, veteran crew could accomplish.
Good good
Then 40 seconds instead of the 20 second in stock or whatever
All the above seems consistent with my understanding of dive times. The IXD2 had the longest average dive time, and I believe was in the area of 40 seconds.
I'll be working on this for the 1.5 release of RFB and will post it as part of an update to the surface draft and dive rate mod.
THere are actually 2 numbers that I need.
Normal dive time
"emergency or crash" dive time.
Also need turn rate numbers and hopefully some acceleration numbers.
On a side note: If the AOTD has them, that would help as they could use whatever I do to the u-boats in their upcoming mod.
Ducimus
03-14-08, 06:45 PM
Personnaly, i think 47 seconds is accurate for a fast dive on a 9D2.
Personnaly, i think 47 seconds is accurate for a fast dive on a 9D2.
I'd vouch on that too. I think the dive times listed in literature are always basically minimums and probably belie the real operational ones in complicated circumstances or when the attack was unexpected. I personally suspect that unless they were on top alert and with some of the tanks pre-flooded, even Type VIIs would probably take well over a minute to dive. I mean it makes sense to use a reasonably minimal value in the game, but I'd take a conservative estimate of that. Better to err on the side of long dives if you ask me!
Old Dog
03-14-08, 10:15 PM
Personnaly, i think 47 seconds is accurate for a fast dive on a 9D2.
I like the new hat Ducimus ! Sorry to see that you're feeling so blue.
Long range sub equals large fuel tanks equals increased flotation to overcome. I imagine that dive times are a moving target. On a long mission, as fuel tanks contain less and less fuel (and more and more air) dive times increase, and that the larger the sub, the longer the time it takes to get the bugger under water.
Personnaly, i think 47 seconds is accurate for a fast dive on a 9D2.
I like the new hat Ducimus ! Sorry to see that you're feeling so blue.
Long range sub equals large fuel tanks equals increased flotation to overcome. I imagine that dive times are a moving target. On a long mission, as fuel tanks contain less and less fuel (and more and more air) dive times increase, and that the larger the sub, the longer the time it takes to get the bugger under water.
Good point! But there's a massive ton of other factors as well - just think of other things like fresh water tanks, or torpedoes, or anything else that basically changes the sub's buoyancy when it leaves the boat. Don't forget the infamous "all hands forward"! (though there's debate if that's really something that happened, given the relatively negligible weight of the crew). There's all sorts of complicated factors that SH4 doesn't really factor in. I really wish the sub's physics model accounted for ballast in a less generic way than it does. It'd really improve the feel of its performance.
But we only have to work with abstracted factors!
I was under the impression that sea water was pumped into fuel tanks as compensating ballast as fuel was expended in order to solve this problem.
Old Dog
03-20-08, 10:14 PM
I was under the impression that sea water was pumped into fuel tanks as compensating ballast as fuel was expended in order to solve this problem.
DS, you're right by golly ! I remember reading that !
I can't believe that the reduction of fuel and replacement by sea water was absolutely 1:1 though.
Admittedly, I was never a sub guy, Army Engineers only, and a Poly Sci major at that !
Replacing expended fuel with sea water would theoretically reduce dive times. The specific gravity of fuel oil is less than that of sea water...that's why it floats !
I've lead a sheltered life and never had a satisfactory explanation of how one can mix sea water and deisel fuel in one tank and operate the ships engines on fuel from that tank, especially given diving and surfacing and the various shakes that depth charges would give to the contents of the fuel tanks. They must have operated on a very conservative estimate concerning the level of un-contaminated fuel remaining in the tanks. Trying to run the engines on sea water is not the kind of experiment I would be willing to try in a war zone. I believe that, even with the sea water, there was a significant amount of air in the fuel tanks.
Thanks for the memory prod though.
Don't forget fuel filters, you gotta have those for diesels or else the injectors, pumps are rubbish in no time. Brings memories, I used to be a farmer! Lots of diesel on a farm!
Sailor Steve
03-21-08, 01:12 PM
I've lead a sheltered life and never had a satisfactory explanation of how one can mix sea water and deisel fuel in one tank and operate the ships engines on fuel from that tank, especially given diving and surfacing and the various shakes that depth charges would give to the contents of the fuel tanks. They must have operated on a very conservative estimate concerning the level of un-contaminated fuel remaining in the tanks. Trying to run the engines on sea water is not the kind of experiment I would be willing to try in a war zone. I believe that, even with the sea water, there was a significant amount of air in the fuel tanks.
And the funny thing is it wasn't just diesel, but also fuel oil. The Iowa class battleships used the same exact method to make sure stability never changed!
NonWonderDog
03-21-08, 03:24 PM
Err... the diesel fuel used in submarines is fuel oil, right? Isn't all diesel fuel not derived from vegitable sources "fuel oil"?
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