Tores mailbox VIIC and VIIC/41 operation and technical details

[tore]

Simon.
That may be.  I think I have seen a drawing of the compensating box in the bottom of the saddletank. See below,  I made a rough pencil sketch indicating where to look for it you have more materials to look into than me.
Tore

[tore]

Simon.
Further to my last post I may add that I believe the compensating pipe goes into the box and a pipe goes out of the box and act like a syphon for the compensatingwater from the box  to the bottom of the saddletank when in fuelmode.
Tore

[NZSnowman]

Hi Tore

A big redrawing of the piping under the decking!

There is little detail we know about this piping outside the pressure hull. The only thing we know for sure is the pressure hull opening (Figure 4).  I initially imagine the piping run just above pressure hull but I now know there is just not enough room to do this.

Next I needed to workout where the pipes enter the saddle tanks. I did this by matching deck hatches. I ended up using the four hatch covers for the exhaust gas and emergency blowing systems.

I also initially imagine the piping for the exhaust gas and emergency blowing systems run just above pressure hull but now I know there is just no room. So I move most of the exhaust gas and emergency blowing piping and Fuel oil compensating piping to just under the wooden deck. This was confirmed in a photo in the book The U-boat By Eberhard Rossler, where you can see one of the exhaust gas and emergency blowing systems pipe just below the deck.


Fig. 1. Openings.


Fig. 2. Piping.


Fig. 3. Hatch covers.


Fig. 4. Pressure Hull opening.


Fig. 5. Close-up.

[tore]

Simon.
Indeed substantial drawing work. A detail with regard to the saddletanks. I guess fwd and aft of the conningtower area the saddletanks have a sharp bend towards the pressurehull which facilitates the pipeconnections to the tanks, see drawing below. I don`t have a good picture of the casing deck in this area but I guess the deckhatches would give an indication of the location for the various deckoperated valves.
Tore
 

[tore]

Simon.
Mainvents fuel/ ballasttanks 2&4.
I had a closer look at the mainvents inlet to the fuel/ ballast saddle tanks 2 port and stb. compairing in it with a GA drawing of 1943 and adjusting it to approximately to your scaledrawing. When using the aft  battery hatch as you use as the fixed point, it looks to me that your drawing has the mainvent inletpipe about 650-750 mm further forward than on the GA drawing.
See drawing below.
Tore

[SnakeDoc]

Tore, one off-topic question related to the high pressure compressed air system. In general, compressed air flasks are connected using "star topology" - with high pressure air distributor as central/control hub. With this air distributor are also connected air compressors (even with two lines - one primary and one backup/secondary).


When there was a need to recharge air flask, after starting compressors, were all air banks filled at the same time or were they filled one after another?
And, when rebuilding air supply, were both compressors running?


http://uboatarchive.net/U-570Plate11.htm


--
Thanks, regards
Maciek

[tore]

Tore, one off-topic question related to the high pressure compressed air system. In general, compressed air flasks are connected using "star topology" - with high pressure air distributor as central/control hub. With this air distributor are also connected air compressors (even with two lines - one primary and one backup/secondary).


When there was a need to recharge air flask, after starting compressors, were all air banks filled at the same time or were they filled one after another?
And, when rebuilding air supply, were both compressors running?


http://uboatarchive.net/U-570Plate11.htm


--
Thanks, regards
Maciek

Maciek.
We normally filled one or two airvessels simultaneously. You wouldn`t operate with many empty many airvessels unless in emergency. Which means normally you took the sub up to periscopedepth (14- 11 meters) and the blew the tanks carefully until you were semi surfaced, starting the diesels and emptied the tanks by exhaust gaspressure.
In this way we had a low airconsumption. We very seldom  used more than one compressor mostly the E- compressor.
There are always exception though, in those cases it is an advantage to use the "star topology". Once we filled the main airduct to the diesel as the main inletvalve in the towercasing was open when diving, luckily the inletvalve in the engine room  was shut. However we were some 5-6 tonnes too heavy and had a quick descend, blowing all the tanks all the way using a tremendous amount of air before we finally stopped at 107 meters. When you then surface you shoot up like a rocket propelled by the expanding air in the tanks and have a spectacular surfacing with a lot of splashing. Then we had to run two compressors, this is the reason why you always want to have full airvessels. It is not the way to surface though.
Tore

[NZSnowman]

Simon.
Mainvents fuel/ ballasttanks 2&4.
I had a closer look at the mainvents inlet to the fuel/ ballast saddle tanks 2 port and stb. compairing in it with a GA drawing of 1943 and adjusting it to approximately to your scaledrawing. When using the aft  battery hatch as you use as the fixed point, it looks to me that your drawing has the mainvent inletpipe about 650-750 mm further forward than on the GA drawing.
See drawing below.
Tore

Hi Tore

In December 2009 I noted that two plans had illustrate the aft Battery Hatch in different location. After doing a little more research on why the move the aft battery hatch. I believe they move it for the 3.7cm FlaK and the quadruple 2cm L38/43 U Flak gun support for the lower Wintergraten. I believe they did this for all Type VIIC/41 or any Type VIIC that had a lower Wintergraten with these big guns on.

http://models.rokket.biz/index.php?topic=106.msg5416#msg5416

[NZSnowman]

Simon.
Indeed substantial drawing work. A detail with regard to the saddletanks. I guess fwd and aft of the conningtower area the saddletanks have a sharp bend towards the pressurehull which facilitates the pipeconnections to the tanks, see drawing below. I don`t have a good picture of the casing deck in this area but I guess the deckhatches would give an indication of the location for the various deckoperated valves.
Tore

Tore,

The angle between the saddle tanks and the pressure hull is not as abrupt in the mid section as people think. Here a extremely rare view of U-995 that show you the angle between the saddle tanks and the pressure hull.

From the photo below, you can see why I angle the pipes into saddle tanks and in the foreground you can see the remains of the main vents

[tore]

Simon you are Right about the conningtower area, but just aft and fwd (frame55) of the saddeltanks have a sharp bend. Se pictures below showing the saddletanks joining the pressurehull forward and aft of conningtower of KNM Kaura. I guess you can just see the beginning of the bend aft of the conningtower on your picture as well.
Tore

[tore]

Simon.
Mainvents fuel/ ballasttanks 2&4.
I had a closer look at the mainvents inlet to the fuel/ ballast saddle tanks 2 port and stb. compairing in it with a GA drawing of 1943 and adjusting it to approximately to your scaledrawing. When using the aft  battery hatch as you use as the fixed point, it looks to me that your drawing has the mainvent inletpipe about 650-750 mm further forward than on the GA drawing.
See drawing below.
Tore

Hi Tore

In December 2009 I noted that two plans had illustrate the aft Battery Hatch in different location. After doing a little more research on why the move the aft battery hatch. I believe they move it for the 3.7cm FlaK and the quadruple 2cm L38/43 U Flak gun support for the lower Wintergraten. I believe they did this for all Type VIIC/41 or any Type VIIC that had a lower Wintergraten with these big guns on.

http://models.rokket.biz/index.php?topic=106.msg5416#msg5416

Simon very interesting I thougth the 1943 GA with snortmast was about the latest VIIC/41 version, but I guess modifications was an ongoing thing to the bitter end.
Tore

[NZSnowman]

Simon you are Right about the conningtower area, but just aft and fwd (frame55) of the saddeltanks have a sharp bend. Se pictures below showing the saddletanks joining the pressurehull forward and aft of conningtower of KNM Kaura. I guess you can just see the beginning of the bend aft of the conningtower on your picture as well.
Tore

I have always found this area of the u-boat hard to draw, the saddle tanks/pressure hull, saddle tanks shape & the wooden deck shape. I have never found any real measurement in any of these areas. So it very hard for me to drawing accurate and I have to draw by

[NZSnowman]

Tore,

Here a lot better alignment of the angle between the saddle tanks and the pressure hull. The port saddle tank is the old drawing and the starboard is new alignment of the saddle tank. I think it much better

[NZSnowman]

Tore, do you have any drawings/pictures of the exhaust outlet control valves? I know that this area is very complex and I would love to add some of this detail.

[tore]

Yes Simon.
Having checked my drawings, I guess the sharp edge goes from aft all the way up to frame 32, then rounded at the tower about 9 meters and continues as sharp edge from frame 51 and forward.
Tore