Type VII Torpedo storrage and handling

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TheBlackob
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Type VII Torpedo storrage and handling

#1

Post by TheBlackob » 05 Apr 2022, 15:19

Hello all,

I am new to the whole U-Boat topic, mostly through the games UBoat and Wolfpack, and I got some questions I did not found the answer to.

These are the information I could gather, please correct my on every detail I got wrong:
The Type VII C was able to carry 14 Torpedos, 12 of which for the forward torpedo room.
4 where loaded in the tubes, but how exacly did they store and handle the other 8?
They would store up to 4 torpedos under the floor, and 2 under the bunks.

My questions:
How did they get 4 torps under the floor? From the cut out drawings I found, the torps where not stacked, meaning they all 4 would lie in a row
The holes where under the bunks and only wide enough to for one torpedo on each side, so how did they get the torpedo out of they way to store the next / how did they get it back to the hole to load them into the tubes?

Where did they store the other 2?
I've read about torpedos stored between the pressure hull and the outer hull. Did they do this?
In the games I mentioned, you can reload all 8 torpedos from under water, which would not be possible with externaly stored torpedos.

Did the crew prepare for reloading once they were called to action stations? Like, already removing the beds and lowering the crane assembly.
Or would they only do so once they were told to reload?

Why did it take several minutes to reload a torpedo?
In my naive understanding if prepared correctly (crane assembly already lowered, torpedo already hooked on the crane) it would not take that long to raise alt least the first the torpedo from the ground and insert it into the tube.
What other steps were taken for it to take so long?

Lastly: Could you recommend a book on the topic?

jbroshot
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Re: Type VII Torpedo storrage and handling

#2

Post by jbroshot » 07 Apr 2022, 04:48

From TYPE VII U-BOATS, by Robert C. Stern (1991)

fourteen torpedoes - four loaded in the bow tubes, four stowed at the bottom of the forward torpedo room, one loaded in the stern tube, one internally below the stern tube, two stowed externally under the deck outside the pressure hull (one forward, one aft)

Also, ANATOMY OF THE SHIP - THE TYPE VII U-BOAT, by David Westwood (1984
THE U-BOAT THE EVOLUTION AND TECHNICAL HISTORY OF GERMAN SUBMARINES, by Eberhard Rossler (1981), English version of GESCHICHTE DES DEUTSCHEN UBOOTBAUS (1975)

From what I remember, having toured the Type IX U-505 at the Museum of Science of Industry in Chicago, several times in my youth, there was no crane assembly, the internal reload torpedoes were raised by chainfalls to reload rails or cradle and then moved forward into the tubes. The same rails were used when torpedoes were withdrawn from the tubes for servicing
Reloading was by manual labor and the torpedoes were heavy


TheBlackob
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Re: Type VII Torpedo storrage and handling

#3

Post by TheBlackob » 07 Apr 2022, 11:06

jbroshot wrote:
07 Apr 2022, 04:48
From TYPE VII U-BOATS, by Robert C. Stern (1991)

fourteen torpedoes - four loaded in the bow tubes, four stowed at the bottom of the forward torpedo room, one loaded in the stern tube, one internally below the stern tube, two stowed externally under the deck outside the pressure hull (one forward, one aft)
I only count 12 torpedos in this description...
jbroshot wrote:
07 Apr 2022, 04:48
From what I remember, having toured the Type IX U-505 at the Museum of Science of Industry in Chicago, several times in my youth, there was no crane assembly, the internal reload torpedoes were raised by chainfalls to reload rails or cradle and then moved forward into the tubes. The same rails were used when torpedoes were withdrawn from the tubes for servicing
Reloading was by manual labor and the torpedoes were heavy
Here you can see the torpedo on the rail or what I called "crane" in U995 Afaik the whole rail would come down to the storred torpedo where the holding clips are then attached to it.
If you were to already lower it, maybe already attach the clips to the torpedo and the rail, then my naive understanding would tell me, that you may need a minute to raise it (as it weights about 1.5 tonnes) and another to push it into the tube. But from what I've gathered, the reloading time for a torpedo was about 5 minutes at minimum

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Takao
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Re: Type VII Torpedo storrage and handling

#4

Post by Takao » 07 Apr 2022, 19:07

2 torpedoes were stored in the forward torpedo room above the floor plates.

U-995 was a mid-war VIIC/41 boat, so it's torpedo room may have differed from earlier VII's.

But, the average was 5 minutes per torpedo with a trained crew.

Temistocle
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Re: Type VII Torpedo storrage and handling

#5

Post by Temistocle » 09 Apr 2022, 10:05

Hi, in the astonishing detailed "German G7e Torpedo 1941 (revised)" video, from minute 1:45 you can see the torpedo loading sequence:

https://www.youtube.com/watch?v=CAO2BYZdfE4

TheBlackob
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Re: Type VII Torpedo storrage and handling

#6

Post by TheBlackob » 09 Apr 2022, 12:30

Temistocle wrote:
09 Apr 2022, 10:05
Hi, in the astonishing detailed "German G7e Torpedo 1941 (revised)" video, from minute 1:45 you can see the torpedo loading sequence:

https://www.youtube.com/watch?v=CAO2BYZdfE4
Thank you for that, but I already watched this video. This is actually one of reasons I dont get why reloading would take 5 minutes. In the video the loading sequence is about 2 minutes. Sure, it is heavily simplified, but non the less an avg loading time of 5 minutes would mean about 150% longer than shown in the video. I guess lifting the torpedo is the most time demanding process as it is not really supported by any mechanisms to reduce the workload, but I actually doubt that it would take 3 minutes to lift the torpedo. I would not think that the people who are pulling the chains to lift it, could muster the strength to do this for three minutes straight.

ROLAND1369
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Re: Type VII Torpedo storrage and handling

#7

Post by ROLAND1369 » 10 Apr 2022, 03:42

I would find the total loading time to easily be 5 Minutes. Remember you are starting with with a fired tube which has been filled with water. You have to include the time required to close the outer watertight door cap. Then the time required to pump out the tube until dry prior to opening the inner door. Both of these actions taking s significant time. After raising and putting the torpedo into the tube the tube would then have to be refilled with water and the outer door(bow cap) reopened prior to the tube being ready for firing. In short there are more actions required than merely lifting the torpedo. We have not even mentioned the time required to release the torpedo from its storage gear as well as release the flooring. It all adds up.

ROLAND1369
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Re: Type VII Torpedo storrage and handling

#8

Post by ROLAND1369 » 17 Apr 2022, 14:26

I neglected one additional step in the reloading process. The German torpedo tubes did not directly eject the torpedo with compressed air but used a piston in the tube, pushed by compressed air, which kept the air inside the tube so it did not rise to the surface and betray the firing position of the boat. The piston did not leave the tube and was returned to to the loading door by water pressure when the air in the tube was released into the interior of the boat. This necessitated both the removal and re-installation of a 77 pound piece of equipment upon each reloading further adding to reload time.

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