Tores mailbox VIIC and VIIC/41 operation and technical details

[SnakeDoc]

Hi Don,

How could they over stress MBT 3?  Did they do a HP blow with the Kingston valves and the vent valves shut?  The only place where the Kingston valves for MBT 3 are shut is in the harbor area.

The one way to damage the MBT 3 is blowing it with HP air with the Kingstones shut. As you said, the flood valves should be shut only in harbour area. I can not speculate, if someone could intentionally shut the valves and then blow the tank.

The other way is to blow MBT 3 "too fast" - the Kingstones are opened, but the pressure inside the tank increases because the water can not evacuate through the flood valves fast enough. Theoretically you could calculate the maximum flow knowing the cross-section area of the Kingstones (I believe Mark is good in these stuff). When you exceed this maximum flow, the pressure inside tank can not be released and can damage the tank.

The similar issue is when you blow negative buoyancy tanks - the operators had to carefully monitor the pressure of the admitted air to avoid the damage of the tanks.

--
Regards
Maciek

[VIC20]

She became an experimental boat in Pillau on 11.11.1944. On 19.12.1945 she collided with U 1131. After repairs in Kiel she became a front boat and was transferred to Stavanger on 1.4.1945, she got attacked by an aircraft on 4.4.1945, due to bad weather (!!!!) she had to stop two times in Kristiansand (4.4. and 5.4.) and once in Egersund (7.4.). She arrived in Stavanger on 8.4.1945 and was sent on 14.4 to Bergen for repairs. On 15.4. she arrived In Bergen and repairs of MBT3 started. At the end of the war she was not transferred to England because she was unseaworthy.



from:
http://www.ubootarchiv.de/ubootwiki/index.php/U_926
And a search for U 926 on http://historisches-marinearchiv.de/projekte/duikboot/ergebnis.php


Seems it was the result of the attack of the aircraft, it is obvious that they could barely keep her afloat after the attack.

[tore]

Mark.
 This is interesting news and a bit more according to the first story I heard, what is a puzzle though is the mentioning of the structural damage to the Tauchbunkers which would mean either MBT 2 or 4, whereas I saw in 1954 the damage in MBT 3 starboard side repaired as well as some dents. I was then told it was due to a depthcharge bomb attack from an airplane, this was later corrected by some documentation from air commodore Derek Wallers to be overstressing by wrongly blowing by the crew. Unfortunately I don`t have access to these documents right now.
Tore

[tore]

In a search for the black flag instructions I came across the surrenderinstruction to the German Uboat and discovered to my astonishment that the Uboats were instructed to fly a large black or blue flag, an explanation why is not given.
Tore

[Don Prince]

Hello Mr. Tore and Maciek,

Jak P. Mallmann Showell did a quick survey of my book about 3 weeks ago and suggested that I have someone to proof read the book and fix the many issues; German "SZ" in place of "SS," many German words were spelled wrong and missing the Umlaut, etc... I have gone over the German text in the Sheet Indexes and corrected what I believe was missed or incorrect in the original text from uboatarchive.net. In addition, I have corrected some of my many poorly worded sentences.

I have uploaded my latest version of Skizzenbuch 11 x 17 - M to dropbox which will be the printed version for my Leather Post Binder.  This will be printed sometime during the first week of September, and this is what I will take to Schiffer Publishing the next week.  There are several blank pages in the first section for Publisher information and the foreword.

Mr. Tore would you please review the contributors section about you and If you approve, or if you would like to add any personal data, then please let me know, and would you please review page 340 with the changed information on MBT 3.

Maciek, If you would like to add a photo and any personal information about yourself in the contributors section, then please do so.  Your emails and postings on this web site have made a significant contribution to my U-Boat education and Skizzenbuch.

All, Please feel free to make any suggestions or corrections because I would like to get this book published in a version that is near excellent in documentation, and presentation.

Kind Regards,
Don_

[VIC20]

How much german is in your book? I could take a look on it.

[Don Prince]

Hi Mark,


There are about 34 pages of German Text, but the type is in a very large MS Word 18 point format for the indexes and some pages range from 3 lines to about 20 lines.  Not that huge...


Mark, If you send me an email, then I can go to dropbox and send you a link to "Skizzenbuch 11 x 17 - M" and I only ask that you not distribute the PDF because the Book will be published by Schiffer Publishing Ltd. here in the USA with international options.


My email address is donprince5207@comcast.net


If you have time to scan through the book, them please advise me of your opinion and if you spot any issues with the illustrations or text, then please advise me so.  The book is highly illustrated and the text is fairly brief by design.


Kind regards,
Don_

[VIC20]

email sent

[Don Prince]

Hi Mark,


My wife Maureen and I just got back from dinner...  I went to dropbox and sent a link.  Please let me know I it does not work?


Regards,
Don_

[VIC20]

I've got it.

[Don Prince]

Hello Mr. Tore,


While I was re-doing your info, I googled "Gosport" and found a photo of an A Class Alliance S67 which looks stunningly like a U-Boat with the sail updated...


Regards,
Don_

[tore]

Don.
The "A" class was very different from the VIICs, much larger, 1385 tonnes surfaced 1620 submerged, 85,5 meter O.A. 61 crew, 6 bow torpedotubes and 4 aft, and designed after the Pearl Harbour experience for the Pacific. The dome on the bow is the Sonar.
The CO had his own cabin in a small separate pressurehull next to the tower.HMS Alliance is a very well known submarine to me as she was stationed all the time in Gosport at HMS Dolphin when I was there. The class as such never took part in WW2 as only two submarines were commissioned before the capitulation. The sail came after my time but you clearly see the folded hydroplane very much different above the waterline.
The resemblance of a VIIC might be due to the "A" class bow flare as the Atlantic bow on the later VIICs.
Tore

[tore]

Don.
Skizzebuch MBT 3 Kingstons.
I have read your page 354 on the MBT3 Kingstons. May be you make it a bit complicated and to me it gives an impression the threaded rod with the travelling nut (yoke) is fitted on a atwarthship bulkhead. I guess it is on the alongship centre bulkhead. The greaselines do not have to be flexible as they are fitted to the fixed points bearings on the centre alongship bulkhead. The Kingstons are opened into a recess in the keel, well protected. I have tried to show my idea on the image below.
Tore

[Don Prince]

Hello Mr. Tore,


I found a photo of the keel being constructed, so I can make a correction based on the Keel structure. Could you post the photo that you used with your drawing?  It looks like the screw jack may be raised a little by the keel structure, so I will redraw and the make a correction and post for your approval.


Regards,
Don_

[Don Prince]

Hello Mr. Tore,


Does this drawing look OK?  I added a guide bar in back of the carrier and the reasons are:
1. We don't have the real engineering drawings.
2. You don't want the carrier applying torque pressure on the Kingston drive rods.
3. It only seems logical.


Regards,
Don_