Tores mailbox VIIC and VIIC/41 operation and technical details

[tore]

Hi Tore

Just letting you know that were will be no new drawings for the next few days. I am taking a break from drawing and catch-up on some other work.

Simon.

Fueloil compensating valves fuel oil saddle tanks.
The upper drawing you are showing is the system outside the pressurehull and I don`t believe the valves are operated from inside the pressurehull. The fuel/ballast saddletank 2 and 4 starboard and port are just made of light steel sheets and do not withstand any large pressure. They are equipped both as full fueloil bunkertanks and  full ballast tanks with all the connections required. The encircled valves have two positions either in direct connection with the head/buffertank in the tower or in contact with the sea via a small compensatingbox in the bottom of the tank. As fueltank the first position shall be used to ensure the compensating head is allways positive but not exceeding the differential pressure (the height difference between the headtank in the tower and the fueltank). Eg. irrelevant of the ambient pressure regardless the diving depth. 
Tore

Tore, that dimension do you think this pipe would be? I was thinking about 75 mm.

Simon.
To me 75 mm diameter seems to be on the large side. I don`t think it would be any bigger than the fuelpipe from the tanks entering the engineroom as seen on the picture below previously displaid.
Tore

[tore]

Simon
It sounds strange but I guess there are other things going on in the world but VIICs. Looking forward to seeing your upgraded drawings in due time!


Tore

[SnakeDoc]

Hi Tore, Simon


Take a look into quite old thread here:
http://models.rokket.biz/index.php?topic=106.msg9557#msg9557


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Regards
Maciek

[tore]

Hi Tore, Simon


Take a look into quite old thread here:
http://models.rokket.biz/index.php?topic=106.msg9557#msg9557
 Hi Maciek.
Interesting thread. I agree to your identification of the Kingstons. However the biggest pipe/duct is to my opinion too large for being a soundingpipe, in fact too large for any liquid. My suggestion would be it is possibly the main ventpipe joining the stb ballasttank 2 to the commom  main ventvalve operated from the control room, it is only in use when ballast/fueltanks 2 port and stb are  used as ballast tanks. The pipe is indeed pointing downwards, but the appearant heavy corrosion  could have removed the support, anyhow I  don`t have any other suggestion right now.
 As the seawater compensating pipe is only supplying the same volume of liquid as the fuelpipe take out of the tank, I don`t see any reason  that the compensating pipe should have to be of an other dimension than the fuelpipe shown on my picture above.
Tore

[SnakeDoc]

Hi Tore

However the biggest pipe/duct is to my opinion too large for being a soundingpipe, in fact too large for any liquid. My suggestion would be it is possibly the main ventpipe joining the stb ballasttank 2 to the commom  main ventvalve operated from the control room, it is only in use when ballast/fueltanks 2 port and stb are  used as ballast tanks. The pipe is indeed pointing downwards, but the appearant heavy corrosion  could have removed the support, anyhow I  don`t have any other suggestion right now.

Isn't this pipe too thin for vent duct? On this plate:
http://uboatarchive.net/U-570Plate28.htm
is given cross-section area: 3,167 m². Based on this, I would estimate the diameter for about 1 m.
Also, here is Simon's drawing showing this arrangement:
http://models.rokket.biz/index.php?topic=106.msg10098#msg10098
Comparing to the wreck's photo, it seems that vent ducts are a little bit larger.

As the seawater compensating pipe is only supplying the same volume of liquid as the fuelpipe take out of the tank, I don`t see any reason  that the compensating pipe should have to be of an other dimension than the fuelpipe shown on my picture above.

Well, that's the point.


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Regards
Maciek

[tore]

Hi Maciek.
The VIICs are well known to have a quick divingtime and have a remarkable Kingston flood openings, but having openings in excess of 3 square meters in a pipe under the casing, I would believe, is too much. It would require a ventdiameter of nearly 2 meters almost the size of the conningtower across. I guess the crosssection area described in  the diagram refer to the 4 Kingston valves eg. floodarea of seawater into the bottom of the saddletank . That would be approximately  4x 0,8 square meters which, looking at the 4 square Kingston openings, seems to be correct. Down below I have posted  sketches showing the various components relation to the diameter of the pressurehull 4,7 meter. The distance between the frames is app. 0,5 m .
In the area of this ventpipe  the max. height between the casing deck and pressurehull is, I guess, 0,70 m. If you compare the vent pipepipe drawing for fwd. ballastanks port and stb. plate 28 with the drawn frame hight app 15 cm, you would end up with a pipediameter of approximately 250 max 300mm, easily fitted under the casing deck and probably not too far away from the biggest pipe shown on the wreck. The  bend on the end of the pipe could be where the pipe would have entered the saddletank.
Tore

[tore]

Hi Maciek.
Further to my latest post I`m showing below a detail of my ventpipe theory. The emergency shut off for each individual ballasttank is showing the pipedimension, as you see the pipe is of a moderate size.
Tore

[NZSnowman]

Hi Tore

Dani, over at U-Historia as updated his 'Fuel' page.

http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&sl=es&tl=en&u=http%3A%2F%2Fwww.u-historia.com%2Fuhistoria%2Ftecnico%2Fvisitaguiada%2Fvisita.htm

[tore]

Simon this is exellent, I`ll have a closer look at it later today.
Tore

[tore]

Simon.
Fuelsystem
The thread shows some interesting new drawings and photos. The English translation is not easy to understand as some strange words  and sentences are used. I guess the translator do not fully understand the system which is a must for a correct technical English text. I stick to my short and incomplete description of Nov. 25Th. and if somebody would have a question based on the new pictures and drawings I shall be happy to answere if I can.
Tore

[SnakeDoc]

Hi Tore,


thanks for drawings illustrating scale problem. Location of cross-section area (near vents drawing) confused me totally and I forgot about estimating sizes and diameters.


I have got some kind of operational question: as far as I know, the primary station for helmsman was located in conning tower, and the second one was in control room (I think there was also possibility to move control panel from conning tower to the bridge, when performing docking maneuvers (or so on).  When RNoN operated KMN Kaura, which station was used typically (conning tower or control room)? Did it depend on cruise condition (submerged/surfaced)? Also, if helmsman was in conning tower, was there enough space for operating (riding around) fixed-eye-level periscope?


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Thanks, regards
Maciek

[tore]

Hi Maciek.
Submerged we usually had the helmsman placed in the controlroom , together with the hydroplaneoperators. The reason for that is the officer on watch was  responsible for both functions and you want to be in physical contact with all three. During surface patrol in peacetime and fair weather it could happen the helmsman was on the bridge as well as during manoeuvring during docking, otherwise in the controlroom. Diving station the helmsman was in the controlroom.  During attack some CO wanted to have the helmsman in the conningtower but as far as I remember he was mostly in the controlroom.
Surfaced in rough weather ( when the bridge was washed over) we  operated the sub from the controlroom using the navigation periscope and shut the top hatch.
You might find a difference between the German way of operation as they used the engineering officer as diving/trimming officer whereas we and the RN used a navigator, No1, for this function. Our engineering officer was used during attack for calculating distances and stationed in the controlroom, No1 was in charge of the helmsman and hydroplanes/trimming and stationed in the controlroom as well.
Tore

[tore]

Maciek.
Helmsman space in conningtower.
I see I forgot to comment on the helmsmans space in the conningtower. I don`t think it was very spacey,but it didn`t obstruct the turning of the attack periscope. If you look at the sketch below you see the distance between the periscope and conningtower pressureside turned 180 degrees leaving "plenty" of space for the helmsman. Note the the conningtower hatch is placed off center midship. The helmsman in heavy winter clothings shows the space.
Tore

[SnakeDoc]

Tore, thanks for your comments on helmsman stations and control room parties duties.
Well, indeed, from drawings it seems, that there is enough space in conning tower for
helmsman and periscope operator. I'm not sure, but wasn't there a third person - TDC operator?


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Regards
Maciek

[tore]

Hi Maciek
I guess it could be 3 persons in the conningtower, but then it would be cramped. We usually  only had the CO and sometimes a TDC operator in the tower during attack. As I said the helmsman was usually in the controlroom as NO1 was in charge of both the trimming, hydroplanes and navigation (helmsman).
Tore