Author Topic: Tores mailbox IX C and IX C/40 operational and technical details  (Read 17655 times)

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Offline SnakeDoc

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Hi Don,


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 the plate 10 is no sign of the emergency blowing system. I guess, the drawing was modified (the salvage system was removed), but title not. I think it is normal, that in the late-war more and more inconsistencies appeared.


From the Design Study:
Quote
14.  Salvage air arrangements, while shown in sketch books and text material were not actually installed in surrendered vessels.


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.


"The emergency release of the ballast" - it means the emergency blow, i.e. procedure of blowing ballast (with normal blowing system) at depth. As you know, normally blowing at depth was avoided, because it used a lot of compressed air. First it was desired to decrease depth dynamically (using speed and hydroplanes), and finally blow ballasts near the surface (this required less amount of air than blowing at depth).
That's why blowing at depth was called emergency blow.


"The emergency release of the ballast" was not related with the emergency blowing system ("Notausblasenanlage"). "Notausblasenanlage" was rather salvage system, which made possible to blow the ballasts (from the outside - by divers) of the sunken boat. Because it was usable only in the areas, where boat can not sunk very deep (practically < 100 m, below the divers cannot descent, I guess Tore will explain this further), it was installed only on new boats that were directed to the training in Baltic sea, and on training units. Because during training many accidents could occur, the  salvage (emergency blowing) system could make possible to salvage the boat and rescue the crew. After the boat passed the training and was combat-ready, the salvage system was removed.


--
Regards
Maciek
« Last Edit: 08 Oct , 2016, 05:12 by SnakeDoc »

Offline tore

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Don. I fully agree with Maciek. The wording emergency release of ballast might be an old expression  deviating from a system of the WW1 submarines where the boats very often carried a mechanical fixed ballast attached to the keel, this ballast could in some cases consisted of lead. In emergency you could release the ballast from the controlroom and surface the boat. However when depthchargers were introduced, the ballast had occasionaly a tendency to be released by the depthcharge attack and the system was abandoned on the WW2 uboats. As in many naval expression may be some people still used the old expression "drop the ballast".
Tore

Offline Don Prince

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Hello Mr. Tore and Maciek,


I have a problem with Plan 9, the text sheet says there is an item (g) a grease fitting, but I can not find one on the print?  Any thoughts? Also the drawing for the bow and aft buoyancy tanks has the drain valves item (f) outside of the pressure hull.  I don't believe that is correct...  What do you all think?


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

Offline Don Prince

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Hello Mr. Tore and Maciek,


I have a translation problem, or things just don't match up with the text sheet and Plan 11. I'm having problems with the German text for items (c) and (d).  Item (c) looks like an external gate valve to me, and Item (d) looks like an internal emergency blowing cock or hand wheel.  All assistance is appreciated...


also Plan 11 calls out the ballast tanks for a IX C and the drawing is for a IX C/40 U-Boat... That part I can handle.


Regards,
Don_
« Last Edit: 09 Oct , 2016, 00:05 by Don Prince »
A man's got to know his limitations...
Harry Callahan, SFPD

Offline tore

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Don
I guess the system is quite similar to the VIICs. The Cs are the external gatevalves for isolating the external reserve bunkertanks when in fuel mode. The ds are the emeregency shut off valves operated from inside for the external vent ducts of the ballasttanks. The possible reason for a confusion is that plan 9 has exchanged c and d.
Tore

Offline Don Prince

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Hello Mr. Tore and Maciek,


I believe the Items I marked should be within the pressure hull and not in the aft buoyancy tank or within MBT 8 as drawn in the original German diagrams. This German version of this Skizzenbuch has the title cover for the IX C/40 U-Boat, but many of the diagram Text sheets reference the IX C U-Boat (MBT 2). Apparently, the control for the shipbuilding documentation was in disarray as early as August of 1943. See my attached drawing...


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

Offline tore

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Don.
I am not sure I have full understanding of your question. The way I see it is the image shows the mechanical operation of the vents of fore and aft buoyancy tanks which are outside the pressurehull having an arrangement of mechanical operation by a wheel inside the pressurehull. The cocks f are on the greaselines to the arrangements.
Tore
« Last Edit: 12 Oct , 2016, 06:15 by tore »

Offline Don Prince

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Then this is what is confusing to me...


Item (f) is listed as "Entwässern Entlüftungsleitung bei Frostgenfahr Taunchbunker 4 Stb bzw Bd."
Item (g) is listed as "Fetten - - - zB Flutklappe Tauchbunker 2 Stb."

In order to pump grease into the bow and aft lines, then the line and valve must be inside the pressure hull and not outside as drawn.  It looks like the descriptions were transposed again, and I don't see any item (g) on the print (Previous drawing uploaded)?

Regards,
Don_
« Last Edit: 13 Oct , 2016, 19:48 by Don Prince »
A man's got to know his limitations...
Harry Callahan, SFPD

Offline tore

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Don
I don`t think it is full correlation between your German text and plan 9 it could possibly refer to another plan.
Tore 

Offline Don Prince

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Hello Mr. Tore,


I absolutely agree, the German Text does not match Plan 9's drawing in the book...  Early on, I recognized that the Skizzenbuch was for the type IX C/40 U-Boat, but some of the text pages still referenced the type IX C U-Boat physical characteristics. The German Skizzenbuch copy that I have looks to be a transition book from the Bundesarchiv. Therefore, I had to cover both U-Boat types in order use the text sheets and the drawings.  Basically, the only difference between the type IX C and the type IX C/40 is the IX C is more complicated because of the presence of MBT 2 and all the hardware required for the ballast tank and the RFO option.  Physically, the IX C/40's U-Boat's beam is 0.1 meters wider than the type IX C U-boat.  That's it!


I have discussed this with Maciek and I have drawn a modified Plan 9 and produced a Type IX C drawing which seems to match the original text page that I uploaded.  The only question that remains unresolved for me is item (f) the "Drainage Vent Pipe for Freezing Danger MBT 4 Port and Starboard" and item (g) "Grease Fitting - - -  For Example: Kingston Flood Valve MBT 2." There is NO item (g) in the drawing, so are the 4 lines from all the Kingston flood valves a drainage line or a grease fitting?


I have attached my drawing of the Plan 9 for the type IX C U-boat.


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

Offline tore

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Don.
I cannot see any use for drain on the Kingstons and certainly not for danger of frost. So I guess the "f" for the Kingstons would be shut off cocks for the grease lines. I Guess the only need for venting and waterdrainage in case of frost would be the venting pipesystem with gatevalves and emergency flapvalves below the casingdeck. The "e" is clearly marked as a drain in the system. However it is strange to name "f" cocks both as drain and grease cocks, hence it might be another systemsketch they are refering to where the "g" cocks are shown as well.
Tore

Offline Don Prince

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Hello Mr. Tore and Maciek,


I have suspended work on the Type IX Skizzenbuch until I get through the clean-up on the Type VII C Skizzenbuch.  I should have the cleaned-up version in dropbox in about 2 weeks.  However, If you all have any suggestions, then please let me know...


Maciek, about my Internet provider Comcast rejecting your email.  I called and talked with then 2 days ago and they were supposed to fix the problem.  I haven't had any issues with emails from Jak Showell in the UK.  I think it may have to do with your email address "Snakedoc", I can see them thinking this is spam!!! Can you try and email me again and let's see if they resolved the issue...


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

Offline tore

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Don.
As to Macieks problem with US rejection of E-mails. I experienced the same as mine ended up in the US spambin in some of the states. I changed my E-mail address and everything is now OK.
Tore

Offline Bob Tomlin

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Happy New Year Tore,


I know you said last time I had a question that you had more experience of type VIIs than IXs, but I thought I'd try here with this question if that's ok as i'm not having much success finding out about these anywhere else yet.
Here's a sketch of two things that I can see on type IXC/40 U-889 in period photos.



The top 'thing' is something I see on type IXs quite a bit in photos. They are usually found over the deck 'flap-type' hatches sometimes immediately forward of the magnetic compass housing
or sometimes on the hatches midway betweeen the tower and bow on the foredeck. There's often a longer version of these over the hatches at the stern end of the boat too.
All I can make out in photos are the sketchy sort of details that I've drawn above and that might be enough for 72nd scale, but I did wonder if you might have ever come across these or something like them and knew what they are or how they work/attach?


The bottom 'thing' is something that I've seen in photos on some Type IXs (including the U-889) which looks to me like a sort of bar/rod that 'locks' over part of this type of hatch.
I've seen this type of hatch on some type VIIs as well, so wondered if you might have come across anything like this and knew again what it is and how it works? Not all hatches of this type seem to have this 'bar' across them so I wondered if it might be a modification/later introduction or something?




Thanks very much for any help.
Bob.
 


Offline tore

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Bob.
As you probably have noticed my PC crashed and I have not been able to communicate for the last 3 weeks which I regret. The marker buoy hatch is a leftover from the earlier VIIC design which contained two markerbuoys able to be released from inside the submarine for emergencies. They were removed sometime in 1942 but several VIICs delivered after that time had the marker buoycontainers installed without buoys. Even good old U 995 had the forward container(not the aft), although due to the Schnorchel it was replaced from off center ( port) at appr. frame 60 to in front of the Ascaniacasing (on U 995 the old type). On the image below you see me almost standing on the hatch.
The "bar" you are refering to is unknown to me and seems to be a quick temporarely securing to prevent the hatch to be flung open in case of depthcharging.