Tores mailbox VIIC and VIIC/41 operation and technical details

[OldNoob]

WOW didn't realize the diving angle was that steep.

[Don Prince]

Battery design...


The air entrance opening is designed in such a way that during a boat’s inclination up to 35° in any direction no acid is spilled from the cell.

[tore]

Don.
Diving angle and depth difference.
I am afraid you have misunderstood my sketches of illustrating the relation between diving angles and pressure differences (depths). On my first sketch (below) my idea was to show the Kingstons in MBT 3 marked green as an indication that the green marks are the free flood gates of the MBTs, meaning the points where the seawaterpressure set the differential hullpressure in relation depthdifference caused by the diving angle. So the green markings fwd. and aft are only markings of the freeflood areas of MBT1 and 5. as you know there are no Kingstons on these inlets. At even keel you would notice there is a higher pressure in MBT 3 than MBT 1 and 5. A practical consequence of this is that it would require more air per M3 tank volume to empty MBT 3 than MBT1 and MBT 5 at even keel. Under normal circumstances this would have impact when blowing the tanks by exhaust gases. You start to blow the saddletanks having the Kingstons at the highest position ( lowest counterpressure), continue blowing MBT1 and 5 having the next lowest counter pressure until you are that high up that your MBT3 gets an acceptable low counterpressure for the exhaust. Thus it is no attempt to indicate the position of the hydroplanes by green markings as they are irrelevant in this case.
Tore

[tore]

WOW didn't realize the diving angle was that steep.

This is a crash dive angle which normally is not common. It requires some skill as you have to watch, what in the Royal Navy submarineservice is called the Duchess Ass, which is the ultimate aft end. If this part is too high above the surface you have a problem with the thrust of the propellers. The ideal angle is when the wind deflector on the bridge and the Duchess Ass is descending the seasurface simultaneously.
Tore

[Don Prince]

Hello Mr. Tore,


The labeling on the first drawing "Free Flood Gates" resolved the issue for me! I think it was needed to help the reader as well...


I uploaded the latest print version of "Skizzenbuch 11 x 17 - M" into dropbox...


Thanks you!
Regards,
Don_

[tore]

Don
Your last Skizzenbuch uploading is correct.
Tore

[Don Prince]

Hello Mr. Tore,


I have completely gone through Skizzenbuch for hopefully a last time looking for any words that should not be used when describing anything within a U-Boat.  Those words which you have impressed upon my newly learned vocabulary such as closed/shut, dive tanks/ballast tanks, ventilation valve/vent valve (2 very different systems), flood valve/Kingston, dive plane/ hydroplane, and of course wench/winch.  (Wench) Obviously we don't want women with loose morals on a U-Boat; except in a crewman's romantic dreams.


The only thing I don't have yet is the foreword written by Jak P. Mallmann Showell. I believe he wants to wait until the publisher produced an approved version of the book. He liked the book's general idea and format, but took issues with the German text, and perhaps my writing skills.  I got help from Mark Hessburg with the German text, and I have attempted to improve my writing skills.


I have uploaded the version of Skizzenbuch 11 x 17 - M that I will send to Schiffer Publishing along with my Leather bound metal post binder to be used as a general layout guide for the publishing entry personnel.


Again, thank you for all your help with Skizzenbuch...
Kind regards,
Don_

[NZSnowman]

I have attempted to improve my writing skills...

Hi Don,

I know that you mean

I have spend the last fours weeks writing, rewriting and some more rewriting my thesis for my Master's.

[tore]

Don.
I guess a book like yours is never finished, but I admire your stamina and courage to go through the whole process. Looking forward to seeing the complete book. Same goes for Simon, you two have contributed a lot to improve the understanding of the VIICs constructions and operation.
Tore

[Don Prince]

Hello Mr. Tore,

The regulation tank configured for the deep diving configuration discharges about 100 liters/10 meters when diving using the main drainage pump in the 2 stage configuration.  The initial air pressure in that tank was set to 10 to 12 Kg/cm2, and the tank design is for a maximum of 14 Kg/cm2. While diving, the tank's internal air pressure will be reduced, but this is of no consequence. The opposite actions take place when the U-Boat ascends to periscope depth and the water is pumped into of the tank and the internal air pressure increases to the previous state.

If the dive was to escape an enemy depth charge attack, then I would head off in a desired direction to assure I escaped the surface vessels.  Every once in awhile I would stop and listen to assure I'm not being followed. Then at some point, I would initiate a surfacing procedure. My reason for this thinking is that I don't want surface vessels waiting for me to bring the U-Boat up to a ramming depth or a shallow depth charge depth. If the U-Boat were coming up to the surface and the enemy was setting quietly waiting, then they could possible listen and hear the pumps taking water into the deep diving regulation tanks. Does my thinking make sense?

The regulation tank configured for the shallow diving configuration may take in water by allowing the tank to vent internally into the pressure hull, or remove water from the tank by increasing the tank's internal air pressure.  I believe these maneuvers are done while running at periscope depth; they don't want to run the pumps and create noise.

When the U-Boat tanks are in the Reserve Fuel Oil configuration only one regulation tank is available, a Port and Stb saddle tank.  I thought they could use one side for the deep diving configuration, and one side for the shallow diving compensation.  Is that correct?  Was there any preference as to which (port of stb) tank was assigned to the deep diving configuration?

Regards,
Don_

[tore]

Don.
Tne way of operating a VIIC during various attacks and counterattacks varies depending on the time and the technical development both with regard to the air superiority,Sonar and Asdic. On the net San Fransisco Maritime National Park Association you shall find the submarine commanders handbook ( U.Kdt.Hdb.)for a VIIC issued in 1942 in force as from 1943. You shall find the German Navys recommendation to the CO for maneuvering under various circumstances, including escape of a depthcharge attack.
I guess at that time the advice was to change depth dynamically by speed and hydroplanes not by using regulating tanks pumping or flooding and use the diminishing displacement without regulating to speed up matter. When required depth is obtained I guess you eventually had to compensate by careful pumping/blowing the regulating tanks depending upon the CO`s judgement.
When you are surfacing, you would use dynamic forces and not pump in regulating water, you rather use flooding without using the pump and venting the tanks inside the submarine. I guess I would use both tanks simultaneously preventing atworth list.
Tore

[Don Prince]

Hello Mr. Tore,


Is atworth list a roll or tilting effect? I google atwort list and I only find a location for Atworth in the UK...


Regards,
Don_

[tore]

Don.
I am afraid it`s a bad spelling for athwart, used for a list either to port or starboard .
Tore

[Don Prince]

Hello Mr. Tore,


Thank you for the info...  No problem with the bad spelling.  That's a problem that I have been dealing with for decades along with my dyslexia.


Regards,
Don_

[tore]

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