Author Topic: Tores mailbox IX C and IX C/40 operational and technical details  (Read 17609 times)

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Offline Don Prince

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Hi Maciek,


Could this be it?


Regards,
Don_
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Harry Callahan, SFPD

Offline SnakeDoc

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Hi Don,

Could this be it?


I don't think so. From the wiring diagram it seems, that switch (fwd/aft/off) is integrated with controller (not as separate box).

On the photo from the design study there is visible controller with one large, horizontal handle and smaller switch below. I guess that this selection switch is 3 position switch (vorn/acht/aus).

I have attached the photo, where I marked the switch. The photo is low-resolution, but one can see some details of the controller.

I doubt, if we can find the controller on the present photos from U 505 control room. Some equipment was removed for investigation in corresponding labs, some was removed when converting to museum and so on.

Regarding the box you have marked on your photo, I think that it is distribution box (maybe for Ordering and Reporting installation - BuM Anlage). I have found other view of this box. Please compare with the similar the box in the U 995 control room (see attachments).

--
Regards
Maciek
« Last Edit: 23 Sep , 2016, 15:00 by SnakeDoc »

Offline Don Prince

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Hi Maciek,


Yep! I believe you are correct about the selectable 3rd hydroplane controller unit location.  This controller allows them to switch-out a defective BBC hydroplane unit (fwd or aft).  However, they could have simply went manual on one BBC control unit and the other BBC unit could continue to run electrically; they wouldn't be tied together by chain drive unless both units were switched to manual.


It looks like the whole purpose of the 3rd control unit was they did not want to go to manual control of a hydroplane!  Why?


The electrical drawing for the rudder BBC control unit indicates the tower rudder BBC unit was just unlatched and taken to the bridge with the cable running through the tower hatch. I don't believe they would want to water proof a receptacle for the controller on the bridge.  Also, there is a cut-off switch to disable the tower BBC rudder unit in the control room.  I suppose they would disable the tower BBC unit if the helmsman was in the control room, or the tower got flooded.  Let me know if you find the cut-off switch...


Regards,
Don_
A man's got to know his limitations...
Harry Callahan, SFPD

Offline SnakeDoc

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Hi Don,

Yep! I believe you are correct about the selectable 3rd hydroplane controller unit location.  This controller allows them to switch-out a defective BBC hydroplane unit (fwd or aft).  However, they could have simply went manual on one BBC control unit and the other BBC unit could continue to run electrically; they wouldn't be tied together by chain drive unless both units were switched to manual.

It looks like the whole purpose of the 3rd control unit was they did not want to go to manual control of a hydroplane!  Why?


Well, in my opinion, the scenario is as follows: the electric drive for the aft/fwd diving planes fails (electric motor, power or control). So this (aft/fwd) diving planes needs to be controlled manually. The electric motor is decoupled pneumatically, and the driving shaft is connected. The driving shaft is driven by respective handwheel.


Now, I suppose, due to length of the shaft (25-30 meters) and many couplings and joints between the handwheel and diving planes gear, the designers anticipated difficulties in movement the shaft by one operator. So they provided the gear for coupling both handwheels together, so both operators could use their strength to drive resistive shaft.


But if both operators were controlling one diving planes, the other one has to be controlled by another man. Assuming, that this other diving planes set was not-damaged (could be controlled electrically), this was done by means of the third controller by another crew member.

The electrical drawing for the rudder BBC control unit indicates the tower rudder BBC unit was just unlatched and taken to the bridge with the cable running through the tower hatch. I don't believe they would want to water proof a receptacle for the controller on the bridge.  Also, there is a cut-off switch to disable the tower BBC rudder unit in the control room.  I suppose they would disable the tower BBC unit if the helmsman was in the control room, or the tower got flooded.  Let me know if you find the cut-off switch...


I cannot locate this switch on the U 505 photos. I suppose, it's missing. In U 995's control room this switch (labeled as Seitenruder) is near the rudder controller in the control room (see attachment).


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Regards
Maciek

Offline Don Prince

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Hello Mr. Tore and Maciek,


The photo attached shows the bow of U-505 and the flooding slots and the flood gates near the torpedo chute. You can see internal flooding slots for the bow buoyancy tank through those huge flooding slots on the torpedo chute. The drawing attached shows the bow buoyancy tank layout where there is a fairly large space below the bow buoyancy tank.  My prints refer to the area that includes the space above and below the torpedo tubes as "Durchfluteter Raum" or Flooded Room. Could the space above the upper flood gates just be considered as part of the bow buoyancy tank?  There doesn't look to be any means to vent that upper area?


Regards,
Don_
A man's got to know his limitations...
Harry Callahan, SFPD

Offline tore

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Don.
Based on the GA plans of VIICs I guess the IXCs bow buoyancy tank might be something as my image below, the floodgates would probably be the first line of gates from the bowdeck .
Tore

Offline SnakeDoc

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Hi Don,


on the attached drawing, the buoyancy tank is marked with green color, and I believe, that volume (given in technical data) 11,89 m3 and 12,89 m3 (at type IXC and IXC/40 respectively) refers to this green area.


However, as you noted, the upper part of the free-flooding volume (marked with grey color) also can be considered as part of buoyancy tank, because when you are blowing buoyancy tank, the joint volumes green and grey are blown.


So I think, that strictly speaking, the buoyancy tank is only the green part, but some space below (grey) can be considered as a part of it as a side effect of flooding slits located just above torpedo tubes.


One can ask, why designers did not locate these flooding slits higher, just below the buoyancy tank (i.e. between grey and green areas)? I almost sure, that it's because of the large flooding gates inside the torpedo tube recess. These large flooding gates are intended to catch any air bubbles, that can escape from the torpedo tube during the torpedo launch. These air bubbles would float toward the top of the buoyancy tank and there be stored, instead of floating to surface and betray the boat position.
Such design was developed later into Schwallfang, used on type XXIII U-Boats.


Any other flooding slots between these "catching holes" and the bottom of buoyancy tank would corrupt this design.


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Regards
Maciek


Offline tore

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Maciek.
I guess the grey area may be considered as the variable buoyancy part of the tank which fluctuate as the boat pitches on the surface compressing the green area as the effective constant bow buoyancy. I have not been able to locate the bow buoyancy vent and operation arrangement, do you have any details Don?
Tore
« Last Edit: 26 Sep , 2016, 02:20 by tore »

Offline Don Prince

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Hello Mr. Tore,


I'm still looking for drawings similar to the Type VIIC diagrams with all the valves.  The only thing I have is the photo of U-505 and I point to the metal grate above the vent valve for MBT  8 (Bow Main ballast Tank).


Regards,
Don_
A man's got to know his limitations...
Harry Callahan, SFPD

Offline tore

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Don.
I don`t think the bow buoyancy vent could be operated mechanically from the controlroom it was probably operated locally as on the older type IIVCs or even pneumatically.
Tore

Offline SnakeDoc

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Hi Tore, Don,

I don`t think the bow buoyancy vent could be operated mechanically from the controlroom it was probably operated locally as on the older type IIVCs or even pneumatically.


according to type IXC Design Study, bow and stern buoyancy tanks have vents operated manually from the bow and aft torpedo room respectively.


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Regards
Maciek

Offline SnakeDoc

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Hi Don,

I'm still looking for drawings similar to the Type VIIC diagrams with all the valves.  The only thing I have is the photo of U-505 and I point to the metal grate above the vent valve for MBT 8 (Bow Main ballast Tank).


I believe, you marked the metal grate above the vent valve of the buoyancy tank. To the right the man-hole for access to the buoyancy tank is visible.


I believe, that the vent valve for the MBT 8 is located under wooden deck, further aft.


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Regards
Maciek

Offline Don Prince

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Hello Mr. Tore and Maciek,


Yes, I agree the vent valve for MBT 8 is under the wooden deck.  Also. none of the main ballast tank vent valve hand wheels are located in the control room.  It was much different in the type VIIC U-Boats. See the attached drawing...


Regards,
Don_
A man's got to know his limitations...
Harry Callahan, SFPD

Offline SnakeDoc

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One more thing regarding the third diving plane controller: while looking photos of the vent valves, I have found the photo of U534 control room (after salvage). You can see there a rusted BBC controller, the same as in U889 control room.


Regards
Maciek

Offline Don Prince

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Hello Mr. Tore and Maciek,

The Type IX C/40 print on Plan 10 refers to an MBT blowing and emergency blowing system… I sure don’t see any emergency blowing system on that schematic? At least not to the hardware extent that was available on the early Type VII U-Boats. They can’t blow the Fuel 1a and Fuel 2a bunkers because there are no Kingston flood valves; they could only blow MBT 1, MBT 5, and MBT 8 which are the normal ballast tanks. However, if they are in a dyre position, they could open the Kingstons and blow the RFO tanks; MBT 3, MBT 4, MBT 6, and MBT 7…
 
Would that be the emergency blowing system?


On her second war patrol starting on 1.12.42 U-175, a type IX C U-Boat, encountered a heavy air attack which resulted in extensive damage. The U-boat sank stern first to a depth of 310 meters (1,017 feet), which was well beyond the hull's tested crush depth. The emergency release of the ballast reversed the plunge into the deep and saved U-175 to fight another day. On her third and last war patrol starting on 10.4.43, U-175 encountered two depth charge attacks by the US Coast Guard cutter Spencer. U-175 surfaced heavily damaged and 12 crewmen were lost and 41 became PoW.
 
Regards,
Don_
« Last Edit: 08 Oct , 2016, 01:21 by Don Prince »
A man's got to know his limitations...
Harry Callahan, SFPD