Author Topic: VIIC/41 - Schematices drawing  (Read 330618 times)

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Offline NZSnowman

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Re: VIIC/41 - Schematices drawing
« Reply #1515 on: 29 Mar , 2018, 15:02 »
Dougie, have you look into the Medium-sized vents above central drainage area for 'late war' Type VIIC and Type VIIC/41?


Offline NZSnowman

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Re: VIIC/41 - Schematices drawing
« Reply #1516 on: 31 Mar , 2018, 00:17 »
Some early testing on the central drainage area




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Offline dougie47

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Re: VIIC/41 - Schematices drawing
« Reply #1517 on: 31 Mar , 2018, 12:32 »
Hi Simon,

Although I have not looked into this for the late war boats in any depth, I do believe they were the same as the early boats. In other words, some had the evenly-spaced arrangement and others the paired arrangement. At a rough guess I'd say there were more paired than evenly-spaced but it would take time to analyse this for accurate figures.

I think U 1305 had the paired arrangement. I'm not 100% certain but maybe you could look into that if possible. It is not always that obvious to see the paired arrangement and it often only becomes apparent if one careful looks for it in photos.

Note also that every boat was slightly different. The holes would be cut by hand so dockyard workers would vary in terms of how "paired" they would be.

There was also differences between the pattern on either side.

If you need more info just shout.

Cheers,

Dougie

PS Glad to hear about Mr Tore

Offline NZSnowman

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Re: VIIC/41 - Schematices drawing
« Reply #1518 on: 31 Mar , 2018, 13:00 »
Dougie, we have two fantastic photos of the port side of U-1305 which I base my model on. As U-1308 had anechoic tiles I will also do a anechoic tiles flood holes.
 
Doing the flood holes and rivals on this casting in the model is a nightmare, as each 500 mm section of steel plate is slight different to each other, because of the slight twist and different incline of the steel plate.
 
So officially the flood holes and rivals are not perfectly spared like we all see on 2-D drawings ;D

Offline NZSnowman

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Re: VIIC/41 - Schematices drawing
« Reply #1519 on: 31 Mar , 2018, 13:26 »
 Dougie, there a small error on page 64 of The Wolf Pack: A Collection Of U-Boat Modelling Articles.
 
 “U-boats had ribs which were spaced at regular 60cm intervals...
 
They are spaced at 500 mm, with two spaced at 550 mm also.

Offline dougie47

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Re: VIIC/41 - Schematices drawing
« Reply #1520 on: 31 Mar , 2018, 15:36 »
Hi Simon,

Thanks for pointing out the error. The source I used was page 31 of Robert C. Stern's Type VII U-Boats which say 60cm. But I am happy to be corrected on this as I am sure your calculations will be right.

Cheers,

Dougie

Offline Howiek

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Re: VIIC/41 - Schematices drawing
« Reply #1521 on: 02 Apr , 2018, 00:51 »
Dear All,

sorry to interfere here, but Stern talks about the ribs of the pressure hull, which indeed were spaced at 60cm (at least most of them). The ribs of the outer hull were spaced at 50cm.
I am just in the middle of putting all of them together........

Cheers,
Thomas
« Last Edit: 02 Apr , 2018, 00:57 by Howiek »

Offline dougie47

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Re: VIIC/41 - Schematices drawing
« Reply #1522 on: 02 Apr , 2018, 12:14 »
Hello Thomas,

Many thanks for this. I definitely made an error. I was talking about the ribs which are visible in the central drainage area. But Stern talks of the ribs of the pressure hull which are completely different. Sorry for the confusion.

Cheers,

Dougie

Offline NZSnowman

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Re: VIIC/41 - Schematices drawing
« Reply #1523 on: 06 Apr , 2018, 17:03 »
Pressure Hull Casting Mid Section - Hatches


Fig. 1. While modelling the middle section of the pressure hull casting, I noted three hatches (purple).



Fig. 2. Aft hatch (400 x 250 mm).



Fig. 3. Aft Venting Value Access Hatch (900 x 500 mm). I was not able to corfrim the means of fixing this hatch but I believe is by screws.


Fig. 4. Forward Venting Value and Exhaust Gas Manifold Access Hatch (1400 x 500 mm). I was not able to corfrim the means of fixing this hatch but I believe is by screws.


Fig. 4. Open forward Venting Value and Exhaust Gas Manifold Access Hatch.
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Offline falo

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Re: VIIC/41 - Schematices drawing
« Reply #1524 on: 23 Apr , 2018, 09:22 »
Hi Simon,

I have found an interesting report from a member (Mr. Martin Beisheim) of U-67 (Typ IXC) on the Website of "Deutsches U-Boot-Museum". The letter was written 1985.

Link: http://dubm.de/das-gummiboot/

Beisheim wrote about the Alberich coating which was applied to U-67. Here is my short summary of this letter with focus on Alberich issues.

]U-67 got the rubber coating in 1941 in Wilhelmshaven (Shipyard: Westwerft) during repairs between trials and war patrol. The boat got a "roof" and "curtains" of canvas to protect the boat from observation. After that kind of mantling the whole outer hull was sandblasted. It was important to got a complete dry working environment Beisheim stated. The crew of U-67 had to stick the tiles to the hull. Shipyard workers and other uboat crew members asked what was going on behind the curtains but Beisheim and his comrades were strictly forbidden to talk about their work. He wrote that the complete outer hull and the diving rudder and rudder were coated with rubber.

He described the glueing of the tiles as following: The tiles were from black rubber with a measurement from 2 x 1 meters and two parted: One part was perforated and stuck on directly on the hull, the second part was a closed rubber tile which covered the first one. Every tile had a thickness of 1–2 millimeters. The perforated tiles had different holes altering in diameter and distance and were related to the thickness of the outer hull. So the pressure hull got a different coating (resp. hole pattern of the tiles) then the diving tanks or the metal sheets of the conning tower for example. The rubber was supplied by IG-Farben, the company sent their own workers to the yard to help and instruct the crew of U-67 during the works. After the rubber tiles were glued to the hull they were pressed with a roller to the sandblasted steel. After the whole boat was glued with rubber, the U-67 was painted grey with a special rubber color.

During the journey from Wilhelmshaven to Kiel the first rubber tiles detached from the hull. When U-67 arrived in Kiel it revealed that more then 20% of the rubber coating had to be replaced. So the uboat was covered again with canvas for dryness matters and curious views protection. Beisheim wrote that the replacement was a "nasty work". Shipyard worker helped the crew of U-67 and galvanized iron ledges were fitted at the tiles seams, they had to drill and to tap threads in the hull. When the job was completed U-67 was relocated to Apenrade (Denmark). The research vessel "Strahl" did some testings with radar reflections in Denmark, the result was that the absorption of ASDIC impulse was not totally ensured. The tests were continued in Norway (near by Trondheim) after U-67 was again relocated. Gradually more and more rubber tiles detached during the test phase because of the stream during cruising. The crew began to cut of the loose tiles. Before U-67 started the Atlantic war patrol in 1941 the boat had to visit again a shipyard to dry-dock (this time in Bergen/Norway) and removed all loose tiles mainly from the hull under the waterline because of the rattling noise occurred whilst plunge. A new coating was not scheduled.

In addition Beisheim wrote that he had seen a VIIC boat in Kiel (mid-1942) with a black coating which surface structure was equipped with small knobs, he did not remember the number of that boat but he nicknamed it „schwarzer Streuselkuchen“ („black crumble cake“).

That much to Beisheim and his report.

Some thoughts:
– I suppose Beisheim could not know the difference between synthetic and real rubber so he used „rubber“ to describe the anechoic tiles.
– The different hole patterns oft the tiles depending to steel thickness of the hull seem to be a very complex proposition.
– I think the „black crumble cake“ description is very interesting. I reckon that the „knobs“ were the reversed shape of the well known Alberich tiles (with the hole pattern). Due to material shortage and time savings during idle time it could have been a clever idea, because there is only one tile necessary and not two for coating. What do you think about the „crumble cake“?


Regards
falo