Author Topic: Type VII - Schnorchel Placement  (Read 22989 times)

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Offline SnakeDoc

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Re: Type VII - Schnorchel Placement
« Reply #15 on: 23 Jan , 2012, 10:34 »
Hi Tore

U 995  had a different snort mast with a newer electropneumatic shut off float (german Ringschwimmer) and a radardetector on the top just installed at the end of the war March 1945.
Did the KNM Kaura had all her service the original, german elektro-pneumatic head valve?
Has it been left unmodified?
--
Thanks, regards
Maciek

Offline tore

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Re: Type VII - Schnorchel Placement
« Reply #16 on: 23 Jan , 2012, 13:07 »
Hi Maciek!
She was still at at the yard Trondhjems mek. verksted,Norway  where she got her snort when the war ended , so the germans never operated her with the with the snortmast and thus the electro-pneumatic headvalve was the original one all the time. I really don`t know why the germans exchanged the mast on the Laboe U 995, may be the hinged-float type was the most representative type, for a war memorial sub.  She was "laid up" in a fjord till  we converted her by removing the guns and wintergarten whereupon we put her into service Dec. 1952. The conningtower was a bit different from the original VIIC type.  The allied navies having air superiority didn`t made use of the snorting as the germans at the end of the war and for us the snorting was a new experience and we had many interesting events before we really got the grip on how to handle the sub.
Regards Tore

Offline tore

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Re: Type VII - Schnorchel Placement
« Reply #17 on: 23 Jan , 2012, 13:25 »
Hi NZSnowman!
As a newcomer I have unfortunately not seen your drawings. Did you made any interiors of the the E-room? The  fantastic Junker freepiston compressor and the Rootsblower on the main engines? These are details which shows top german engineering and I would love to see same illustrated with your drawingskill.
Regards Tore

Offline NZSnowman

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Re: Type VII - Schnorchel Placement
« Reply #18 on: 23 Jan , 2012, 13:25 »
She was still at at the yard Trondhjems mek. verksted,Norway  where she got her snort when the war ended , so the germans never operated her with the with the snortmast and thus the electro-pneumatic headvalve was the original one all the time. I really don`t know why the germans exchanged the mast on the Laboe U 995, may be the hinged-float type was the most representative type, for a war memorial sub.

I had totally forgot about this, I remember reading about this a few years back.

we had many interesting events before we really got the grip on how to handle the sub.

 :D

Offline NZSnowman

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Re: Type VII - Schnorchel Placement
« Reply #19 on: 23 Jan , 2012, 13:45 »
Hi NZSnowman!
As a newcomer I have unfortunately not seen your drawings. Did you made any interiors of the the E-room? The  fantastic Junker freepiston compressor and the Rootsblower on the main engines? These are details which shows top german engineering and I would love to see same illustrated with your drawingskill.
Regards Tore

Here my drawing of the E-room so far, below is a picture link to a larger verison for you.


 
 In this topic you can see many of my drawing http://models.rokket.biz/index.php?topic=106.0


Offline tore

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Re: Type VII - Schnorchel Placement
« Reply #20 on: 24 Jan , 2012, 00:31 »
Hi NZSnowman
I`m amaized with your drawingskill. It migth be somewhat confusing to some with all the smaller piping around the main exhaust outlet. As you probably know part of it is due to the airdriven gindingmachine connected to the exhaustvalvedisk via a gearpinion to a gearrim on the disk.  At every dive one of the engineers had to start the grinder and rotate the disk to remove the carbondeposit on the seating. If the valve was leaking the trick was to wait till the we got 2-4 meters waterpressure on the disk. At periscope depth the pressure was to high for the grinder. An unpopular sideeffect of the airdrive was in the event of a bad leaking valve you build up an overpressure in the sub.
Regards Tore

Offline SnakeDoc

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Re: Type VII - Schnorchel Placement
« Reply #21 on: 24 Jan , 2012, 02:20 »
Hi Tore

She was still at at the yard Trondhjems mek. verksted,Norway  where she got her snort when the war ended , so the germans never operated her with the with the snortmast and thus the electro-pneumatic headvalve was the original one all the time. I really don`t know why the germans exchanged the mast on the Laboe U 995, may be the hinged-float type was the most representative type, for a war memorial sub.  She was "laid up" in a fjord till  we converted her by removing the guns and wintergarten whereupon we put her into service Dec. 1952. The conningtower was a bit different from the original VIIC type.
Good to know this - I didn't know the snorkel was altered after passing the boat to the Germany.
I will try to find the photos of the KNM Kaura to get the exact view of the elektro-pneumatic head valve.
 

The allied navies having air superiority didn`t made use of the snorting as the germans at the end of the war and for us the snorting was a new experience and we had many interesting events before we really got the grip on how to handle the sub.

I have the question - I know, that boats equipped with the M.A.N. engines - which were charged by turbine blowers - had problem with exhaust gases back-pressure - they were modified in such way, that exhaust/intake valve overlap had to be decreased. I'm not sure if the mechanically charged G.W. engines had the same problem? Did their engine timing also had to be changed? I guess not, but I woud like to get information from the first hand.


Also, while snorting, there were constant under-pressure inside the sub (when the snorkel head valve was not closing). Did it affect noticeably the operation of the distilling plant unit?



As you probably know part of it is due to the airdriven gindingmachine connected to the exhaustvalvedisk via a gearpinion to a gearrim on the disk.
I have got another question regarding to the low pressure air installation - I have noticed, that hull valve in the E-motor/Aft torpedo room (E-motor cooling water intake and torpedo compensating tanks flooding) has also connection to the low pressure air installation. I wonder what is for - I guess it was used to "crack" the valve - to help opening valve at greater depth or with the jammed valve. Is that right?


Another question related to the heating system - I know, that type VII boats were equipped with the steam heating installation used only in harbour and powered from the U-Boat tender. While visiting the U-995 I have seen no sign of the steam heaters.  I imagine, they had looked like on these photos (below the hatches)

(http://www.uboatarchive.net/U-570Photo17.htm)

(http://www.uboatarchive.net/U-570Photo23.htm)


Was the steam heating installation removed from the KNM Kaura?


And in the end - when the Norwegian Navy taken over the U-995 - did you have manuals, drawings, technical specifications? Did you use the knowledge of former german sailors or you were discovering and reverse engineering the sub?


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Thanks, regards
Maciek
« Last Edit: 24 Jan , 2012, 03:04 by SnakeDoc »

Offline tore

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Re: Type VII - Schnorchel Placement
« Reply #22 on: 24 Jan , 2012, 04:59 »
Hi SnakeDoc!
I have a photo of me inspecting the rising of KNM Kauras snortmast showing the details and shall publish same as soon as I can figure ut how! ( May be my grandchildren can show me)
Regards Tore

Offline tore

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Re: Type VII - Schnorchel Placement
« Reply #23 on: 24 Jan , 2012, 05:22 »
SnakeDoc !
The main engines were Krupp Germaniawerft made and was not turbocharged. Allthough the germans had a turbocharger system called the Buchi system, the VIIC engines had a mechanical driven superchargesystem. The blower (Roots blower type) was clutched in via a double cone frictionclutch at a certain load to boost the top speed. The blower was never used at lower loads. The tuning of the exhaust/inletcams was adopted to higher exhaustpressure even on boats without a snort as the VIIC used the dieselexhaust to blow the ballasttanks when half surfaced in order to save HP air.
Regards Tore

Offline tore

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Re: Type VII - Schnorchel Placement
« Reply #24 on: 24 Jan , 2012, 05:57 »
Snorting underpressure
Would you belive it, we didn`t use a destillingplant  and the permanent underpressure was not a problem except for the cook. We never operated more than one diesel at the time and always with the propellor disengaged, chargeing the batteries.The other E-motor/generator took care of the propulsion. We tried out direct dieselpropulsion while snorting but learned that the hydroplanes and the boat was not very suitable for high speed submerged and the mast was not designed for the load. The snorting challenge was definitely bad weather and fluctuation of airpressure,I experienced an officermate bursting his eardrums.
Regards
Tore

Offline tore

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Re: Type VII - Schnorchel Placement
« Reply #25 on: 24 Jan , 2012, 06:15 »
Heating
 The LP connection on the hullvalve in the E-room.   I`m a bit rusty on this and hope to revert. Non of the VIIC`s we had in operation did have steamheating. We operated for weeks in the artic and never had a problem.
Regards
Tore

Offline tore

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Re: Type VII - Schnorchel Placement
« Reply #26 on: 24 Jan , 2012, 06:39 »
Drawings, manuals.
Hi Maciek!
Good question. The story is. I was taken rigth from my graduation at the naval academy and sent to the Royal Navys submarine trainingcenter HMS Dolphin at Gosport near Portsmouth. Attended an Engineering Officers trainingcourse learning practically evrything about the RN`s  A, T, S and U/V class submarines only to return to Norway and to my astonishment realized I was assigned a VIIC of which I did`t know much. The design difference of the two countries submarines was significant. In 1953 we did not have any connection with the germans and the documents/manuals were were not overwhelming. Thus you had to do it the hard way, trying and failing. Some of the failings were exciting. Eventually we become pretty good in handling the boats I dare say.
Regards Tore

Offline tore

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Re: Type VII - Schnorchel Placement
« Reply #27 on: 24 Jan , 2012, 09:51 »
Hi Maciek!
Trying to post a picture of KNM Kaura`s snortmast half raized. the young handsome man with white cap inspecting it is me!
regards Tore

Offline NZSnowman

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Re: Type VII - Schnorchel Placement
« Reply #28 on: 24 Jan , 2012, 11:34 »
Hi Maciek!
Trying to post a picture of KNM Kaura`s snortmast half raized. the young handsome man with white cap inspecting it is me!
regards Tore

Maciek, There are several more pictures of the snortmast on page 147 of U-995 by Eckard Wetzel.
 
« Last Edit: 24 Jan , 2012, 12:13 by NZSnowman »

Offline NZSnowman

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Re: Type VII - Schnorchel Placement
« Reply #29 on: 24 Jan , 2012, 11:42 »
Heating
 The LP connection on the hullvalve in the E-room.   I`m a bit rusty on this and hope to revert. Non of the VIIC`s we had in operation did have steamheating. We operated for weeks in the artic and never had a problem.
Regards
Tore

 Very interesting! I try last summer to add this system to my drawing, but give up, after I could not found any evidence of it on U-995 or found any additional information on is system. I was planning to take another look at it later.
 
« Last Edit: 24 Jan , 2012, 12:14 by NZSnowman »