Tores mailbox VIIC and VIIC/41 operation and technical details

[VIC20]

I think this is because of the atlantic bow - or different height of the painting of the water line?


Many WWII pictures and some models shows the holes below the waterline.

[/size]
[/size][size=78%] [/size]

[tore]

mark.
Absolutely correct. I guess however one thing is fixed, the freeflood gates are the gates for the bow bouancy tank and as such they have to be right above the tankfloors, see my image below.
Tore

[VIC20]

Looks like it needs to be a little deeper then

[tore]

Mark-
Hold on! Something was not correct as the buoyancy tank does not go all the way to the bow,  it is  a forepeak in between of which I believe the floodgates relates. To me it seems that the two floodgates would be situated at  the level of the rounded fore lower corner of the anchor bay about where my yellow line is drawn on my sketch below. Sorry about that .
Tore

[Don Prince]

Hello Mr. Tore,


Thank you for the information about the Schnorchel locking mechanism.  I updated Skizzenbuch with that and the info about the location of the exhaust line and shutoff valve above the deck casing.  The latest Skizzenbuch was uploaded to dropbox...


Regards,
Don_

[tore]

Mark.
I had a closer look at the bow floodgates this morning and show you my final suggestion as per the images below.
Tore

[VIC20]

So, just a tiny bit lower - thanks. BTW is the anchor bay really that large?

[tore]

Mark.
 Your question on the variation of waterline. The difference in draught at the various images of VIIC might be due to many variables. salinity, temperature, ballasttanks configuration,
fuel, torpedoes, supplies etc.  You did not compensate the draught immediately and some CO liked to have a bow down trim, which was prohibited due to the danger of undercutting.
During warpatrols quite frequently you had the Q tanks filled for allowing quick diving. Thus no wonder there are photos showing different trim and draughts.
Tore

[VIC20]

Yes, sorry I mean the painting of the waterline not the real physical water line.

[tore]

So, just a tiny bit lower - thanks. BTW is the anchor bay really that large?

Mark, I did not checked the anchor bay size. However  the lower corner aft and fwd corner high is between frame 103 to106.
Tore

[tore]

Hello Mr. Tore,


Thank you for the information about the Schnorchel locking mechanism.  I updated Skizzenbuch with that and the info about the location of the exhaust line and shutoff valve above the deck casing.  The latest Skizzenbuch was uploaded to dropbox...


Don.
I checked your to days Skizzenbuch update and it looks OK. One small item. The U 996 did not have a schnorchel during WW2. She came back from her last patrol in March 1945 to have a schnorchel installed and was almost ready end April. Thus she has never been operated as Schnorchel boat by the Germans.
Tore


Regards,
Don_

[Don Prince]

Hello Mr. Tore,


I corrected the history of U-995 as per your information.  In Addition, I got an email from Maciek and he was kind enough to identify several errors on my part about the switchboard and e-motors and made corrective suggestions.   I believe I have made all the corrections and uploaded the latest version of Skizzenbuch to dropbox.  I may need to do some additional work on the speed controller...   That has proven to be a very difficult page!


Regards,
Don_

[tore]

Don.
I checked the Skizzenbuch on the U 995 history OK. It might be of interest to you that her last and 9th mission during WW2 was in the Barenz Sea outside the Soviet Kola peninsula. She attacked the allied convoy JW-65 and destroyed an US freighter Horace Bushnell of 7.176 ts. 13th. of March 1945. Then she returned to Narvik and Trondheim Norway to have the schnorchel fitted.
Tore

[Don Prince]

Hello Mr. Tore,


I like that kind of information and I placed it on page 320 in the latest version of Skizzenbuch which I uploaded to dropbox.  I have been emailing Maciek about Rotary Converters and he gave me some excellent photos and information, so I just had to include that info.  Also. I decided to take his advice and changed the main control panel and auxiliary control panel back to switchboard and auxiliary switchboard.  I called the motor control units the Rotary Switchboards, so that covers all 3.


You know; the more I learn about the Type VIIC U-Boat, the more I find out that I don't know a lot!  You and Maciek are way beyond my limited knowledge, and I have the audacity to attempt to write a book!


Regards,
Don_

[tore]

Don.
I guess you are about to write a book on the VIICs. On the various threads there are a lot of information which could be organized, the problem is to evaluate which info's are the right as many are assumptions.
 The WW2 story of U 995 is a story of an average Uboots operation in the Artic, focusing on the allied convoys to Murmansk. A norwegian has written a book of 97 pages on the subject concentrating on U 995, but included  parts of the other VIICs and one XXIII taken over by the Norwegian Navy.
The book is unfortunately only in norwegian, it contains many interesting details as to the U-boot warfare including  correspondence and interview with Hans Georg Hess, the last CO of U 995, at an age of 21 being the youngest CO of a VIIC ever. He became a lawyer holding a PhD after the war.  He had a meeting with some ex preys ,norwegians convoy gunners,  on board the U 995 September 1992.  I believe he died in 2009. Below a photo of the last German CO of U 995 Hans Georg Hess taken September 1992 on board the museum U 995.
Tore

[Don Prince]

Hello Mr. Tore,


I updated page 320 to include info about CO Hess and I made a correction that Maciek suggested as well.  I uploaded the latest version of Skizzenbuch to dropbox...


Regards,
Don_

[tore]

Don.
The story of U-995 did not end by Hans Georg Hess 9 th. mission. She escaped operation Deadlight as she was not seaworthy for the transfer to Scotland because of the unfinished schnorchel conversion.  She was then put away in one of the small fjordbranches of the Trondheimsfjord by the norwegians. 6 th. of December 1952 she was commission as KNM Kaura by the norwegian navy. I became her chief engineer May 1953, and stayed on board during her period as front line submarine til 1955, when she got a major maintenance and conversion. After that she became a test and training submarine until she was faced out and sold to Germany for 1,- Dmark as museumsboat. Then towed to Kiel, Germany 1965 and eventually after some difficulties, restored in 1970-71 and handed over during an official sermon in Kiel  Oct. 1971 as a war memorial of the german submariners.
Down below are a few photos from my private collection. The lower is from a typical maneuvering situation at the switchboard getting alongside. Apart from the CO at the attackperiscope, I don`t think the photos have been published before.
Tore

[VIC20]

Do you have more pictures of her at that time?

[tore]

Mark.
Yes I have a few, not all are very interesting. Most of my photos are from our missions above the Artic circle and a few from the Trondheim fjords where our submarine pen and main base was. They are all from KNM Kaura ex. U 995.
A strange photo might be that of a test torpedolaunching. We used a dummy torpedo which did not start and just tested the launching system in harbour. A few of the photos I have published before but most of them are never published before .
Tore

[Don Prince]

Hello Mr. Tore,


Great! and the very first photo of the helmsman shows him looking at the Gyro-repeater.  Now U-995 does NOT look to have any of these instruments.  I was emailing Maciek about these instruments yesterday.  Thank you for the photos...


Regards,
Don_

[VIC20]

I've seen pictures of the Wandtochterkompass in U995 before. Guess they removed it some years ago.

[Don Prince]

Hello Mr. Tore,


I added your photo of the Helmsman on page 300 and uploaded the latest version of Skizzenbuch to dropbox.  It getting very close to being finished once I iron out my problems with the speed controller with Maciek's help.  I updated the speed controller again and we'll see... 


Regards,
Don_

[tore]

Don.
Before you finish the Skizzenbuch, I believe there at least two systems worth while to consider, the hydraulics which include both periscopes operations and the schnorchel, and then  the rudder and hydroplane operation including the emergency mechanical hand operation with clutches. Particularly the hydraulic system have a few intricate details, but both are of course vital to a submarine.
Tore

[Don Prince]

Hello Mr. Tore,


I will start looking into the hydraulics and the control for the rudders and hydroplanes...  I believe the rudders and hydroplanes will be fairly easy to do, but I need to do a little research on the hydraulics...  Thanks for your suggestion.


Regards.
Don_

[VIC20]

I still don't understand it - what exactly is the Skizzenbuch?

[Capt Kremin]

Hi Mark


Direct translation is sketch book, however Don's book is a bit more than what most people think of as a sketch book,


Regards
Jon

[VIC20]

Hi Jon,


I'm german, the translation was not the problem    What I mean is what is the plan for this book?

[tore]

Mark.
I am not sure I know Dons plans, but he explained once the reason for making a skizzenbuch was to have a good understanding of the various systemsketches which in some cases was confusing to him. I guess as time went he seems to end up with a book which is a bit more elaborate than an ordinary Skizzenbuch in the German understanding  and hence the name Skizzenbuch could be a bit misleading .
Tore

[Don Prince]

Hello Mr. Tore,


Since the original Skizzenbuck came from the factory for each boat and covered everything mechanical (34 plates just drawings no information).  I decided to explain the functionality of the content of the plates, and then fill in the other areas as well.  I guess I wanted a book that covered most of the basic systems in the type VIIC U-Boat.  I have about 50 books in my library and they contain about 10% of the information I have in Skizzenbuch. 


Now that I am working on the rudders and hydroplanes, I got to a point where something seems strange...  The BBC controller for the rudder is located on the control room forward bulkhead starboard side, and that makes sense.  If they want to go to port the helmsman pushes down on the left (port) button or plunger (he is facing forward).


The hydroplane operators sit in back of the helmsman and work at the BBC controllers mounted on the starboard wall area.  Here is where I get confused; the gauge towards the bulkhead has readings of 25 to 0 to 35 degrees and the other gauge for the crewman in the direction of the stern, his gauge reads 30 to 0 to 30 degrees.


The stern hydroplane has a range of 25 up to 0 to 35 down degrees.  So it looks like the stern hydroplane operator was sitting forward towards the bow???  That doesn't make sense because that would mean the hydroplane mechanical controls would have to cross each other to control the proper hydroplane.  Is that the way it was actually designed?  Or, If during the restoration the museum people swapped the Hydroplane gauges?


Please advise...


Regards,
Don_ 

[Don Prince]

Hello Mr. Tore,


I believe the U-Boat Museum got the gauges swapped...  See the photo from U-570 attached  Is there a clutch lever to engage/disengage the hydroplane manual hand-wheel.  I don't believe they want the hand-wheel rotating while using the push buttons on the hydroplane controller.


Regards,
Don_

[tore]

Don.
I don`t think the fwd hydroplane indicator is swapped with the aft as the dial is clearly marked Vord. Tiefenruder translated forw. hydroplane.  Further the dial for the mechanical indicator (aluminum disc) goes up to 30 degrees see my photo.
If you look careful at the indicator dial it looks as if it has been erased from half of the 25 degrees markings. On some controlroom photos of the rpm repeater for stb engine (propeller) you can see some of the figures are flaking off. I believe the hydroplane indicator is the right one but the dial might have a textdamage.
Tore

[Don Prince]

Hello Mr. Tore,


I took a very close look at the bow and stern gauges and disks on U-995


The bow gauge has a range of 25 - 0 - 35, and the disk range is 30 - 0 - 40


The stern gauge has a range of 30 - 0 - 30, and the disk range is 35 - 0 - (35) (possibly -can't see it)


It looks like the gauges agree with the disks,  I believe that a manual control could get a greater degree of angle like the manual states for the rudder (33 vs 35 when manually driven).


I have come to the conclusion that the manual would be correct for most Type VIIC U-Boats, and U-996's configuration is correct as well.  The manual covers VII's built by 19.9.40.  U-995 a type VIIV/42 and was commissioned on 19.9.43, so what changed?  All the data seems to match up between the VIIC and the VIIC/42 and there seems to be no difference in length, bean, weight, etc,... 


Could the Atlantic Bow have caused a redesign change in the dive plane angles?  Did the VIIC/41 or any later VIIC with the Atlantic bow require a greater forward dive angle to get the wider bow to submerge, and match the Type VIIC dive characteristics with the narrower bow?


What do you think?


Regards,
Don_

[Don Prince]

Hello again Mr. Tore,


I believe you talked about clutches for the hydroplane manual controls.  I don't believe they would want the hand-wheels moving when operating electrically,  Where are they located?


Regards,
Don_

[tore]

Don.
I am afraid I am a bit uncertain on the hydroplane angles. The overall length of the Uboats having the Atlantic bow is about 280 mm longer than the conventional VIIC  bow. According to Simon it is in addition raised gradually 150 mm from frame 104. This alone is not much for changing the design angle of the hydroplanes. However it could be that the flare of the Atlantic bow could influence the reaction time of the boat due to resistance which again could be compensated by different angle relations in some cases. I have not seen any publication or discussion on this subject, so I have to emphasise it is only an assumption.
Tore

[tore]

Don.
The air operated clutches for the hydroplanes are situated locally at the hydroplane gear disengaging the electric drive and engaging the mechanical drive. The operation is controlled from the controlroom, I assume the clutching valves are situated as marked on my image below close to the hydroplaneoperators. As far as I remember the electric and the mechanical hydroplane indicators are operating in both configurations.
Tore

[Don Prince]

Hello Mr. Tore,


I completed the section on Rudders and Hydroplanes in Skizzenbuch on pages 168 - 173 and uploaded the latest versuon to dropbox...  Now to look at the hydraulic source for the Schnorchel.


Regards,
Don_

[Don Prince]

Hello again Mr. Tore,


Figuring out the Hydraulic plate was not a problem (I Think!)...  I will attach my understanding of it.  However, I know where most of the schnorchel components are located, but the general hydraulic components are questionable?  I believe on the hydraulic plate the two main pumps are electrically driven and the other 3 (two in the tower for training and raising/lowering the attack periscope, and one in the control room for the aerial periscope raising/lowering are oil pressure driven pumps.


I don't know the location of the 2 electrical driven main pumps, the 93 gallon oil reservoir tank, and the 3 31 gallon HP oil tanks, and most importantly where the schnorchel taps into the HP oil and Return oil.  It looks like it all may all be in the cabinet area where the schnorchel control valve is located, except for those 4 tanks...


Regards,
Don_

[tore]

Don.
I guess the easiest way is I give an explanation of the system.
The hydraulic system is operating the two periscopes and the schnorchel. It consist of two IMO type screw pressurepumps, one as auxiliary, taking hydraulic oil from a system tank and controlled by micro pressureswitches within a pressurerange govern by the oil level in the system tank. The oil is supplied to three aircushioned accumulators having each a capacity of 118 liters and a pressure working range between 48 to 84 bar. All situated in the controlroom between the attack periscopecasing and  stb. pressurehull. The system is adjusted by filling the accumulators with air  at 10 bar. where upon oil is pumped into the accumulators up to the lowest level testpipe,and the air is admitted to 48 bar being the lowest pressurelevel where the pump has to start.The  accumulators are then filled with oil until the pressure is 84 bar being the max. pressure where the pressure switch is adjusted to stop the pump. The unusual with this system is that the pressure switches are controlled by the static level pressure in the system tank rather than the pressure in the accumulators.
From the accumulators the oil is delivered to a oil slide, after a branch off with stopvalve to the schnorchel, which is controlling the operation of an IMO type screwmotor ( converter) engaging the drivespindle via worm geardrive to both  winches for raising and lowering the periscopes by wire. The IMO type converter is a screwpump able to run as motor (converter) when pressureoil is supplied and the direction of rotation is determined by which inlet the oil is supplied. The oil intake is controlled by the controlslide, see drawing, which again is controlled by the raising/lowering periscope handle. On the sketch, red are the pressurelines, purple are the return. When the handle is pushed down (lowering periscope) the slide admits pressureoil to the endstopper (which is preventing the periscope to exceed the adjusted travel). The endstopper consist of a rod driven by the periscopewinch and having a threaded end engaging internal threads in a sleeve inside the endstopper casing. As the winch rotates the rod, the sleeve travels back and forth between the travel ends and the slide opens for oilsupply and return to the operating slide of the IMO converter moving same up or down allowing pressure and returnoil to the selected inlet/outlet ( selected rotation direction). At the end of the periscope travel the sleeve shut  the supply and open to return on both ends of the slide which is the pushed by the balancing springs on both ends of the slide to a shut position and the periscope stops regardless pushing the periscopehandle beyond the limit.
The attack periscope has a different raise/lower handle but the working is the same. However an additional handle is provided next to the depthgauge. This handle can be switch in by a selectorslide, see drawing. The purpose for this arrangement is to have a man accurately controlling the periscope height above the surface. The attack periscope has a direct footcontrol of the controlslide, skipping  a foothandle, for turning the periscope.
The schnorchel hydraulic system takes its supply and return from the direct supply/returnlines as can be seen on the sketch, then further to the raise and lower handle via hullvalves to the schnorchel cylinder in the casing outside the pressurehull as previously discussed.

[Don Prince]

Hello Mr. Tore,


WOW!!!  I am so impressed with your knowledge of the technical details of this U-Boat.  Sir, you continue to amaze me!


Kind regards,
Don_

[Don Prince]

Hello Mr. Tore'


I updated Skizzenbuch with the latest info and uploaded it to dropbox...


Hydraulic Periscope   pages 213 - 219
Schnorchel  Pages 324 - 331


Regards.
Don_

[tore]

Don.
I had a brief look into your latest Skizzenbook and have a few remarks which I shall revert to a bit later, however right now I shall just mention the hand operation of the hydroplanes.
May be you should include a description of the rather elaborate yet simple mechanical system consisting of rods, stuffingboxes, bearings with grease nipples and bevelgears going from the controlroom to the fwd. and aft torpedorooms ending at the gearboxes with clutches to the hydroplanes.
Tore

[SnakeDoc]

Hi Gentlemen,

here are some additions to Tore's excellent explanations.

The air operated clutches for the hydroplanes are situated locally at the hydroplane gear disengaging the electric drive and engaging the mechanical drive. The operation is controlled from the controlroom, I assume the clutching valves are situated as marked on my image below close to the hydroplaneoperators. As far as I remember the electric and the mechanical hydroplane indicators are operating in both configurations.

The valves controlling pneumatic clutches were marked by Tore correctly. As Tore said, electric and mechanical angle indicators were operating in both configurations (mechanical indicators were moved by means of flexible wire - so called Teleflex system, the electrical indicators were DC systems, utilizing the voltage divider principle).

The clutches were located near the electric motors - the forward motor with the clutch is invisible (under the bow torpedo room floor, in the bilge, between lower torpedo tubes), but you can clearly see the aft motor with the gear and clutch (with the compressed air line connected). There should be noted, that the clutches were engaged remotely from the control room (by means of control valves), but to disengage them, the crew man had to be sent to the clutch and he had to disengage it manually (by means of the handle).


--
Regards
Maciek

[SnakeDoc]

Some comments to the hydraulic system.
On the first photo you can see the control room of HMS Graph (ex-U570) - you can see, that some parts of hydraulic installations related to Schnorchel are missing (or to be more specific - in the control room of U995 there are some additional elements )
I have also attached the drawing, which presents the periscope winch wires.
On the second photo, I have marked the particular elements of the control room periscope winch. The markings are as follows:
1. Periscope lowering/rising "pilot" valve ("Fahrschalter" on the German drawing)
2. The periscope winch drum
3. Hydraulic motor driving the periscope winch/drum
4. The "control" valve" ("Steuerschieber" on German drawing)
5. The shaft for manual rising/lowering the periscope
6. The pulleys for the wires  rising the periscope
7. The guide for the wire lowering the periscope

I have also attached one more drawing, presenting pilot and control valves as well as limit-valve and hydraulic motor.

Finally, on the turm07.jpg photo you can see the winch for the attack periscope in the conning tower, together with the hydraulic  motor and control valve and the shaft for the manual drive.

--
Regards
Maciek

[tore]

Don.
Maciek has published some excellent drawings which I have never seen and I have included his photo of the IMO type converter with lower/raising slide and endstopper which gives a better image of the component. The IMO converter I included as I did not have the German drawings, is a double scewtype for balancing the axial forces on the screw, whereas the German type of converter is a single screw type which means you have to balance the axial forces hydraulically. On the very good cross section drawing of the converter shared by Maciek you can clearly see the balancing bore in the casing going to the balancing piston at the end of the screw. Thank you Maciek for sharing these drawings.
Tore

[tore]

Don .
Macieks pictures of the dogclutches for the hydroplanes gives a good impression how they work. I have made some colour on the components to explain the working. The yellow parts are the parts moving when the electric motors are connected, the normal configuration. On this shaft are two sleeves having rims with outside teeth and a bore with axial four grooves. The sleeves can be moved axially on the yellow shaft having four axial keys matching the inside grooves of the sleeve bore. In normal service the emotor is engaged by moving the left sleeve into the e motor wormdrive wheel which have a bore with rollerbearings on the hyroplane shaft and a bore with internal teeth matching the outer teeth of the left sleeve. As the sleeve is locked to the yellow shaft by the four keys and connected to the e motor by the worm gear, the e motor is the operating the hydroplanes. At the same time the other sleeve to the right is disengaged from a similar unit on the right side and the manual operation is disengaged, the manual operation sleeve is rotating free on the yellow  shaft which is supported in a rollerbearing inside the coupling flanges of the manual driveshaft. When air is admitted to the pneumatic cylinder from the controlroom two forks engaging both sleeves via sleevegrooves and moves both sleeves to the right thereby disengaging the motor wormgearwheel and engaging the internal teeth of the manual drive shaft which then is in operation. The yellow shaft is rotating freely on the roller bearing in the wormgearwheel.
Tore

[Don Prince]

Hello Mr. Tore or Maciek,


On the hydroplane clutch casing where the pressure vessel is located there looks to be a pressure release cap or valve.  Is this to relieve the pressure so the disengage lever cam move back to motor control?


Regards,
Don_

[tore]

Don.
May be you are referring to the springloaded catch?
Tore

[Don Prince]

Hello Mr. Tore,

Oh, I see...  It's sort of like a buffer.  Restricted air in and out???

Don_

[tore]

Don.
It is a springloaded locking pin which rest in the rodgroves keeping the rod and couplingsleeves in the two positions, electric or hand drive. As Maciek says the pneumatic piston controlled from the controlroom works only one way, disengaging the the electric drive /engaging the handoperation by admitting air to one side of the piston (green), the other way has to be set locally by hand thus no airconnection on the other side only venting bore ( blue).  The lockingpin snaps in either of the two rodgrooves by the spring.
Tore

[Don Prince]

Hello Mr. Tore,


I have a problem understanding the working of the end stopper used in the periscope wench raising or lowering.  If we use the detailed drawing provided by Maciek here is what I see...[size=78%]…  [/size]


The internal threads and the shaft look to have the possibility of just a few terns, and then the internal sleeve will come in contact with the top or the bottom of the end stopper casing depending on the drive shaft direction of rotation.  So, it looks like the periscope will not move very far before the end stopper comes to a stopping point and the shaft cannot rotate any more.


The aerial periscope eyepiece is normally in a well and below the control room floor.  Therefore, there is a fairly long distance to move up to be at eye level when standing on the control room floor.  The only thing I can figure is the gearing ratio is such that the bottom of the end stopper represents the bottom of the well and the top of the end stopper represents the maximum height the periscope can be raised.


The end stopper details of the channels on the sides of the sleeve are mostly blacked out.  Do you have a drawing with those details?  I can guess, but I don't like to do that!


As usual. I'm lost in the technical details...


Regards,
Don_

[Don Prince]

I'll guess anyway...


Perhaps this?


Don_

[tore]

Don.
The endstopper controlshaft is driven by a  system from the IMO converter having rotating pto from the drive spindle via a worm gear, with ratio, engaging a gearwheel, with ratio, all reducing the rotating movement which is then transmitted to the endstopper via a chaingear, again a possible rotation reduction. I don't have a drawing of the system, but I post a sketch of the system below. As you see, apart from the internal threads in the endstopper slide there are several reduction elements in relation to the periscopetravel. As it is only an end stopper and not an indicator it does not need to have a big movement.
Tore

[tore]

Don.
Your Skizzenbuch.
On page 168 you are stating: However the U-boats does take on the dynamic diver characteristics when it surfaces with the ballast tanks flooded and used dieselexhaust to blow the ballast. To remain surfaced at that time, diesel power and diveplane upward angle is used.
I am afraid it is a bit different. Normally the VIICs are surfaced by taking the boat up to periscope depth by e-motors and hydroplanes, the ballast tanks are still filled with water and you have normal neutral buoyancy. Then the CO takes a periscope sweep and if everything is OK he  gives the order surface and  the ballasttanks are blown by compressed air. You don`t surface the boat by hydroplanes. At a given point in surfacing the boats metacentric height is reduced and the boat becomes a bit unstable. Depending upon the sea and the submarines relative position the CO evaluate the situation before he orders stop blowing. The reason for this procedure is that you don`t want to be hit by a major wave sideways when you are in an unstable condition hence the degree of airblowing (surfacing) is determined by the circumstances mentioned. When the submarine has semi surfaced to the wishes of the CO, he enters the bridge and if everything is OK he gives the order to start the diesel and blow the residue ballast water by exhaust. The use of diesel exhaust to blow the ballast tanks is to save HP air. You may start the other diesel for propulsion to keep the submarine up against the sea.
Circumstances in wartime might require deviation from the above procedures.
Tore

[Capt Kremin]

Hi Tore


Just to change to subject slightly, external torpedo storage containers, did any of the Norwegian boats still have them?, were they used at all?, if either, did they have a pressure line going to them or were they just a waterproof container?


Regards
Jon

[tore]

Jon.
I believe they were removed on all the boats as well as some of the casing deck containers.
Tore

[Capt Kremin]

Hi Tore,


Thanks for the reply


Regards
Jon

[Don Prince]

Hello Mr. Tore and Maciek,


1.  I added two pages 160 -161 with photos & info about the exhaust blowing manifold valves per Maciek.
2.  I deleted some info about surfacing per Mr. Tore and added info on page 163
3.  I added corrected info about rudders and hydroplanes 170 - 177
4.  I added corrected info periscope hydraulic drive on pages 217 - 225
5.  The schnorchel section is at pages 330 - 337 (I believe it has been checked out?)


Skizzenbuch has grown to 349 pages, so I had to renumber the pages in my 3 Word documents and re-merge them into a single PDF file.  Sections have different page numbers every time I make additions and the additions have to be two pages so the Plates end up on the right side of the book and on an odd page number..


However, I welcome any suggestions or corrections because I what to get Skizzenbuch right!  I have loaded the latest version of Skizzenbuch into dropbox... 


Kind regards,
Don_

[Don Prince]

Hello Mr. Tore,


The ratchet and anti-backup pawl looks to give the crewman the possibility of raising the periscopes manually.  However, I do believe the drive shaft must be disengaged during a normal hydraulic wench operation.  How is this done?


Regards,
Don_

[tore]

Don.
I have looked briefly through you Skizzenbuch (13) edition and have a few remarks related to the exhaustblowing of ballasttanks. As you might have noticed, the HP air hullvalves for blowing the ballasttanks have a non return valve  or check valve as you would say, integrated. The exhaustblowing valves have not, and that calls for some care, otherwise the ballasttanks might be vented through the exhaust system. Thus when you start exhaustblowing you first start the diesel the conventional way by having the inner and outer exhaust flapvalve fully open, then you adjust the pressure to 0,5 bar before you open the main exhaustvalve to the distributionpanel operated from the controlroom. Just to be sure no venting shall occur.
As the internal pressure varies in the different tanks f.i. MBT3 require a higher pressure than the saddle tanks, you blow the tanks separately otherwise the exhaust, taking the flow where you have the least resistance, shall escape. Thus the exhaustblowing is a timeconsuming affair. By the HP airblowing you don`t get the same problem of escaping air, as you normally don't empty the tanks fully  allthough you might have more residue water in the tank having the highest resistance.
I`ll look into the other questions later.
Tore

[Don Prince]

Hello Mr. Tore,


Previously we said the blowing pressure was 1.5 atm which would be equal to 1.5 bar.  Is it OK to use 1.5 bar?


Regards,
Don_

[tore]

Don.
Yes, when the VIICs were at their top the German pressurenominations were  ata which means atmospheres absolute and atu which means atmospheres over. Bar is still used by my generation, but is not correct, barg is more precise meaning atmospheres gauge.  The manometers on a VIIC  usually have a scale starting at 0 meaning the atmospheric pressure. The problem is that the prevailing pressure in the confined space of a VIIC was seldom one atmosphere, usually over or when schnorcheling under. You should compensate for that by having differential pressuregauges as we have discussed before. However in the mannor of speaking amongst the crew talking about pressure, we always meant pressure above atmospheric and 0.5 bar is actually 1,5 bar absolute. The time correct nomination for the VIIC pressures would be exhaustpressure should be adjusted to 0,5 atu or 1,5 ata.

Tore

[SnakeDoc]

Hi Gentlemen,

I have few words related with the hydraulic system and the diving planes.

Although most of type VII U-Boats were equipped with the diving planes driven by electric motors (as thoroughly discussed above), there were two boats, which were fitted with the hydraulic drive of the diving planes for experimental purposes. These boats were U 206 and U 207. I have no details about experiences related with this drive, but one can suppose, that electric motors driving hydroplanes were replaced by the hydraulic motors (the same as for periscope drive) controlled by pilot valves at diving planes control station.
What was the purpose of usage of the hydraulic drive - one main reason would be noise - the hydraulic drive would be quieter than electric drive.

The type XB U-boats (minelayers) were also equipped with the diving planes driven hydraulically.

The concept of the hydraulic drive was elaborated by Germans in the type XXI U-Boat, where not only periscopes were operated hydraulically, but also torpedo tubes muzzle door opening gear, torpedo reload system, forward diving planes retracting gear and finally diving planes and main rudder drive.
There should be noted, that in this case, the diving planes (and main rudder) were driven not by hydraulic motor (and then by worm gear), but directly by hydraulic pistons/actuators.

--
Regards
Maciek

[SnakeDoc]

Tore,

to continue the topic of the diving planes and hydraulic systems - in the US Navy, the Gato and Balao type submarines were equipped with the diving planes driven hydraulically (by means of the pistons/actuators). I have found no information, what was the British practice - could you present how it was done in British way?

--
Thanks, regards
Maciek

[tore]

Maciek.
Limiting my experience to V, S, T and A class British submarines I would say they used by far more hydraulics than the Germans. Apart from the periscopes,- the hydroplanes , rudders, vents and Kingstons were operated hydraulically even the capstans and windlasses. They had different hydraulic actuators depending upon the movement required and they made use of rams pistons f.i. on the vents required relatively small movements, IMO converters and VSG unites were widely used as well. For the hydraulics used outside the pressure hull the oleo systems were used. The oleo system is converting the energy transmission fluid from f.i. hydraulic oil to glycerin omitting the risk of oilslick in case of leakages. When you operated a British submarine you got the impression of a very modern vessel whereas the VIIC was a sturdy oldfashioned full of mechanical rods and gear vessel. Yet the VIIC gave a good feeling as you had direct mechanical contact with the elements you operated.
Tore

[Don Prince]

Hello Mr. Tore,


If we connected a pressure gauge that reads 0.0 bar based on the internal hull pressure as a reference, then the blowing pressure read on the pressure gauge for the blowing manifold would be 0.5 bar?   The absolute pressure would be 0.5 bar, plus 1 bar for the atmosphereic pressure, or 1.5 bar?  That seems confusing...  I would think that the exhaust pressure should be expressed as what is measurable with a pressure gauge.


My question is what pressure does the engine crewman adjust the blowing pressure to when viewing his pressure gauge?  0.5 bar...  Is this the gauge ? (see attachment)


Regards.
Don_

[tore]

Don.
 In the jungle of pressure definitions it is easy to get confused. The way we used the pressuregauges was generally the figures at 0 was atmospheric pressures anything below was vacuum above was pressure. So when blowing the ballasttanks by exhaust at 0.5 at. it meant 0.5 at above the atmospheric pressure. If you were using like 0,5 at absolute you would have been venting the tanks. What sometimes could be a problem was that the overpressure in the boat could be excessive and the manometersan  would show  a higher pressure  as the 0 point could be at 0.1 or 0.2 at. When exhaustblowing this would not occur. The gauge you show could very well be the exhaustback pressure gauge.
Tore

[Don Prince]

Hello Mr. Tore,


As far as exhaust pressure blowing goes, I believe I will stick with the pressure that is seen on the pressure gauge (0.5 atu = 0.5 bar)...

I was thinking (very dangerous sometime), but I never seen any indication as to the location of the hydraulic oil supply tank (over 350 Gallons).  It looks like a suitable space for that large tank would be under the helmsman and plainsmen seat???  am I close?


Regards,
Don_

[Don Prince]

Hello Mr. Tore,


One other question...  the "Fahrtmeßanlage" speed measuring system has a dial that indicates 0 - 20 Knots.  Was it sophisticated enough to take into account for the influence of the ocean current (+ or - knots)?


Regards,
Don_

[Don Prince]

Hello Mr. Tore and Maciek,


I updated Skizzenbuch with added pages 204, 205 on the oxygen system with info from Maciek, and the latest version was uploaded to dropbox (modified date Oct-21-2014)...


Regards,
Don

[SnakeDoc]

I was thinking (very dangerous sometime), but I never seen any indication as to the location of the hydraulic oil supply tank (over 350 Gallons).  It looks like a suitable space for that large tank would be under the helmsman and plainsmen seat???  am I close?

Under the plainsmen and helmsman seat is something like tool cabinet. The hydraulic oil supply tank is located behind the compressed air manifolds. I have attached drawing with its location marked. I have also attached photo with good view of the one hydraulic pump with driving motor. There are also visible pipe leading from the pump to the accumulators and pipe leading from the collecting tank (with large valve).

One other question...  the "Fahrtmeßanlage" speed measuring system has a dial that indicates 0 - 20 Knots.  Was it sophisticated enough to take into account for the influence of the ocean current (+ or - knots)?

No, the log operating on the principle of the Pitot tube measures speed relative to the surrounding water only.

--
Regards
Maciek

[SnakeDoc]

Tore, thank you for your answer.

When you operated a British submarine you got the impression of a very modern vessel whereas the VIIC was a sturdy oldfashioned full of mechanical rods and gear vessel. Yet the VIIC gave a good feeling as you had direct mechanical contact with the elements you operated.

I wonder about diving planes. They are quite crucial elements - if they are damaged (i.e. disconnected from the driving gear) or jammed (especially in "dive" position), they can easily  cause the depth excursion incident. That's why, they are equipped with some backup system - as well driving gear (manual drive) as the mechanical position indicators (apart from electric ones). I wonder, why the German designers decided to use remote mechanical drive from the control room. It would be much safer to provide emergency steering stations locally - in the forward and aft torpedo room respectively (as in the case of the main rudder). I can imagine - that due to depth charges explosions - there are some damages to the relatively long driving shaft lines possible.

As the some kind of interesting fact I can say, that larger U-Boats (type IX and XIV) were equipped with some kind of coupling gear - the both hand-wheels on the plainsmen station could be coupled together to control aft or forward diving planes from both stations - I believe, it could be used, when aft or forward diving planes were operated so hard (due to damages), that one man could not stand it. In such situation, there was additional (third) electric console provided, which was operated by another crew member, who controlled the remaining (undamaged) diving plains pair.

--
Regards
Maciek

[tore]

Don.
The log system is explained very good by Maciek, I can only add the Pitot system is based on a static and dynamic pressure, the dynamic nozzles (two) are place on port and stb bow and the static nozzles are I believe at the forward end of MBT 3.
Tore

[tore]

Don.
I have made a sketch showing the various hydraulic supply components place in the control room. Note the hydraulic tank capacity is 345 liters not gallons.
Tore

[SnakeDoc]

Hi Gents,

The log system is explained very good by Maciek, I can only add the Pitot system is based on a static and dynamic pressure, the dynamic nozzles (two) are place on port and stb bow and the static nozzles are I believe at the forward end of MBT 3.

I have attached photos of the dynamic nozzles on the bow.

Note the hydraulic tank capacity is 345 liters not gallons.

I estimate its size on approximately 110 cm length, 75 cm width and 40 cm height.

--
Regards
Maciek

[tore]

Maciek.
I believe the mechanical emergency operation of the hydroplanes was very sturdy and placed inside the pressurehull could take a lot of beating from depthcharging. However the system required a lot of maintenance (greasing) to stay relyable. A local 3 positions for operations of rudder and hydroplanes would be a challenge for the immediate communication and would require further instruments for immediate response to keep the vessels  positions (angle) which is a combination of operation of fwd. and aft hydroplanes. I guess I would have preferred to maintain the system of a VIIC above three local emergency operations.
Tore

[Don Prince]

Hello Mr. Tore and Maciek,


Thank you for the information about the location of the hydraulic system tank and the speed measuring system...  I updated Skizzenbuch and added the Hydraulic system tank location in the hydraulics section, and the speed measuring system with the rudders and hydroplanes.  The latest version of Skizzenbuch was uploaded to dropbox...


Kind regards,
Don_

[tore]

Don.
I have checked your latest additions to your Skizzenbuch and it looks OK to me. A minor comment which has nothing to do with the understanding of the system. I just accidentally stumbled over your remark in connection with the valve assembly on page 225 :" ... the valves were called a christmas tree because of the multicoloured handwheels." I have previously on this thread warned against making conclusions based on the present state of the museums U 995. The vigorous use of multi coloured items has nothing do with the original.  Today all the red paintings makes the impression that poor old U-995 got the measles.
We did not use the christmas tree expression 60- 70 years ago in Europe, I guess it came from US oil exploration and was used in the beginning as a slang for the cluster of valves on the top  of the drilling hole containing the blow out preventer. The expression reflects rather to the shape of the valve cluster having many branches and not colours as the assembly was not coloured.
Tore

[SnakeDoc]

Hi Tore,

I believe the mechanical emergency operation of the hydroplanes was very sturdy and placed inside the pressurehull could take a lot of beating from depthcharging. However the system required a lot of maintenance (greasing) to stay relyable. A local 3 positions for operations of rudder and hydroplanes would be a challenge for the immediate communication and would require further instruments for immediate response to keep the vessels  positions (angle) which is a combination of operation of fwd. and aft hydroplanes. I guess I would have preferred to maintain the system of a VIIC above three local emergency operations.

Thank you for your answer. Of course, emergency steering stations located locally in aft and forward torpedo rooms would be quite challenging.

Anyway, US Gato and Balao diving planes systems were operated hydraulically. The description can be found here:
http://www.maritime.org/doc/fleetsub/hydr/chap5.htm#5A
As I understand, there is no other way of controlling them than hydraulic. In case of failure of the hydraulic pumps, the only emergency recovery mode is the hand pump. It seems, that in case of damaging the hydraulic piping, the whole system is broken.

On the other hand, the hydraulically driven diving planes on type XXI U-Boats were fitted with emergency hand drive (but only aft pair).
I suppose, that it is because the aft plains have more effect on the control of the submarine than forward planes.

Here is another example - the British Oberon class submarine:
http://maritime.org/doc/oberon/hydraulics/index.htm#pg26

These subs have also hydraulically operated diving planes, and it seems, that after pair has the following emergency gear - in case of damage of the hydraulic system, to the actuating piston controlling the planes can be connected high pressure air, which controls the angle of planes (or sets them to the "surface" position).

--
Regards
Maciek

[tore]

Maciek.
Interesting  information on the British "O" class which at my time was very hush,hush, allthough we had a naval architect reading a paper on the development of the class. Further it gives a documentation of the extensive use of hydraulics of the British submarines compaired to the Germans. Visually an obvious difference between the British ( and US) and the German submarines during WW2 was the forward hydroplanes. The British and US submarines had the hydroplanes well above the surfaced waterline and the Germans well below. There were many pros and cons to both systems. The German having an immediate quick active effect on the diving, the British needed to be folded out and was not active before the bow was submerged. The British was easier to manoeuvre in harbour but had an extra element (folding). The German could have a problem with dropping the anchor and the anchor cable, I have personally experienced the anchor cable being stuck between the hydroplane and guard ( deflector), but the hydroplanes could act as a stabilizing instrument cruising surfaced in rough sea. To a certain extent a similar system is used as stabilizers on large passenger vessels today. I post a photo never published before showing me jumping into the sea in shallow water divingsuit close to the forward folded hydroplane of a British T class submarine.
Tore

[Don Prince]

Hello Mr. Tore,


I have a question about page 164 the second paragraph... It states the compression for blowing the ballast tanks is 1.5 atm (I believe that would be 0.5 atm plus 1.0 atmosphere external pressure  that equals 1.5 atm absolute).


Since you don't specify absolute pressure, would it be wrong to substitute 0.5 atm or atu as read on the pressure gauge in the paragraph just to be consistant?


Regards,
Don_

[tore]

Don.
May be we should refer to your photo of the exhaust manometer in the engine room starting at 0 being the atmospheric pressure, which is app. 10 meter watercolumn fresh water at 4 degrees C. Let us assume the submarine has been surfaced by HP air up to the top of the saddle tanks and that the salinity and temp. makes the seawater specific gravity like the freshwater (not 100% correct). That means we start blowing the saddletanks at a counterpressure of 0.22 mwc,  the counter pressure shall gradually be reduced as the boat raise. If you start exhaustblowing at MBT 3 you shall have a counterpressure of almost 5 mwc which means almost no water is forced out of the tank hence we blow that tank later. MBT 1 and 5 have less counter pressure than MBT 3 so we blow those tanks before 3 as the boat rise further. If we take all at the same time  only the saddletanks are blown the exhaust disappear via the saddletanks Kingstons.
Tore

[Don Prince]

Hello Mr. Tore,


Thanks for the info and drawing....  I got the drawing and info in by changing some wording and moved things around, but all in pages 164 through 166.  The latest Skizzenbuch was uploaded to dropbox...


Regards,
Don_

[tore]

Don.
 I checked your last Skizzenbook (2) on the exhaust blowing which is OK.
Tore

[tore]

Don.
On page 59 in your Skizzenbuch you have two photographs U 570 and U 995 to show two different fuel sample collectors. I am not sure if you have noticed an even more interesting difference on U 570 being commissioned 1941 there is no wheel for venting the bow buoyancy tank whereas U 995 being commissioned 1943 you have the ventwheel next to the ventwheel of MBT 5, in the controlroom see my picture. The explanation you`ll find on plate 28, the earlier version of VIICs had a local venting wheel in the forward torpedoroom as shown on my picture.
Tore

[Don Prince]

Hello Mr. Tore,


Interesting...  I have photos from a U-995 CD that shows two large hand-wheels above both the froward and aft pressure hull passage ways and 3 smaller ones above them. I assume one is for dive tank 1, and the others (?).


Regards,
Don_

[SnakeDoc]

Don,

I can see only two small hand-wheels above - these are hand-wheels for operating gate-valves of the ventilation ducts (located behind the bulkhead).

--
Regards
Maciek

[tore]

Don.
May be you remember the residue venting of aft MBT 2 being the other ventwheel. So where is the venting wheel of stern buoyancytank? Both version of the VII Cs have local venting of the stern buoyancy tank being a barhandle up front of the steeringgear. See the photo. Otherwise I agree with Maciek the other two wheels are for the ventilation ducts.

Tore

[SnakeDoc]

Tore,

May be you remember the residue venting of aft MBT 2 being the other ventwheel. So where is the venting wheel of stern buoyancytank? Both version of the VII Cs have local venting of the stern buoyancy tank being a barhandle up front of the steeringgear. See the photo. Otherwise I agree with Maciek the other two wheels are for the ventilation ducts.

Isn't this handle (marked as "stern buoyancy tank") of the Junkers compressor exhaust valve grinding gear?

--
Regards
Maciek

[SnakeDoc]

I have attached photos of the gate valves located behind aft control room bulkhead (two red wheels). The green wheel is the valve of the HP air bank 3 - which consists of two air flask located in the Petty Officers' Room.

--
Regards
Maciek

[SnakeDoc]

Tore,

the hand wheel for the stern buoyancy tank should be located somewhere between 6th and 7th pressure hull frame - the same as the handle you have indicated.
I have attached close view of this handle - it seems quite strange for the vent valve - I think, it is manual drive for the diesel air-compressor exhaust valve grinding gear.

Anyway, I was not able to identify something else looking like the drive for the vent valve.

[SnakeDoc]

To make more confusion - here is the photo of the aft torpedo room of the U-570:



There are also two valves visible - a little different arrangement than on the U-995...

--
Regards
Maciek

[tore]

Maciek.
I remember we came to a conclusion that this handle would be the grinding (ratchet) for the Junker. When I was looking for the venting of the stern buoyancy tank I realised it was not operated from the control room and that the local rod for the pressurehull entrance was exactly where the we assumed the Junker grinding shaft was. I forgot about the interlock confusion. I still think it has to be the sternbuoyancy tankventing as there are no other indication for this venting. The confusing element is the interlock, it could be to prevent opening the stern tankventing while the Junker was running. The two stroke opposed freepiston balancing was very susceptible to exhaust backpressure. I`ll ponder a bit and revert.
Tore

[SnakeDoc]

I remember we came to a conclusion that this handle would be the grinding (ratchet) for the Junker. When I was looking for the venting of the stern buoyancy tank I realised it was not operated from the control room and that the local rod for the pressurehull entrance was exactly where the we assumed the Junker grinding shaft was. I forgot about the interlock confusion. I still think it has to be the sternbuoyancy tankventing as there are no other indication for this venting. The confusing element is the interlock, it could be to prevent opening the stern tankventing while the Junker was running. The two stroke opposed freepiston balancing was very susceptible to exhaust backpressure. I`ll ponder a bit and revert.

Tore, it is interesting. I think, you are right.

One note - on your drawing you are referring to the outer shell frames. I have marked (with green color) the pressure hull frames and the location of the valve.

--
Regards
Maciek

[SnakeDoc]

From the British report on HMS Graph (ex U-570)

5.  In the case of the Junker's air compressor exhaust valve, the valve floats on the end of the main spindle.  It is rotated by an extension from the valve passing down the centre of the main spindle and is turned by hand.

I have also searched my archive materials and found following description referring to the Junkers compressor:

Die Störungen haben zumeist ihre Ursache darin, daß zu viel Schwallwasser in die Abgasleitung des Verdichters eintritt. Um die besonders bei Seegang auftretenden Anlaßschwierigkeiten zu beheben, ist z. Zt. (April 1941) eine Hilfsauspuffleitungen den Raum und auch eine Verbindungsleitung Stufe I Spülluft bei Alle Booten in Aussicht genommen. Bei einem Boot versuchsweise zwischen Abgasein- und austritt ein Wasserfänger eingebaut. Der Verdichter koonte bei geschickter Handhabung bis Seegang 5 angestellt und in Betrieb gehalten werden.

Not all is clear for me, but I would translate it as follows:

The damages are mostly caused by the fact that too much water enters the exhaust pipe of the compressor. To remove these difficulties encountered especially in rough seas, an auxiliary spaces in the exhaust line were introduced and also introduced the scavenging air line to stage I at all boats. One boat was experimentally fitted with the water-trap between beginning and ending of exhaust piping.The compressor can be skilfully operated up to the  sea state 5.

--
Regards
Maciek

[tore]

Maciek.
Sorry about my drawing which I made in a hurry mixing the pressurehull framing with the outer hull thanks for correcting and Don don't`make use of my drawing, use Macieks green correction.
The German text indicate that they had trouble with water even entering the Junkers exhaust pipe, it seems they already in 1941 tried to make modifications. Of course the stern buoyancy tank was an important element in keeping the exhaust outlet up to prevent intrusion of water in the exhaustpipe increasing the risk of waterstroke, upsetting the balancing and the two stroke scavenging as well.
 I think we can make certain that the handle is the stern buoyancy tank venting handle converted from a conventional vent wheel to a 90 degrees turning handle with interlock preventing the Junker compressor to start ( exhaust valve to open) unless the stern buoyancy tank vent is shut, thereby keeping the stern up and exhaust pipe free from the seawater. I have made a sketch how I assume the interlock is working below.
Tore

[SnakeDoc]

Tore, thanks for the drawing. It looks, that this interlock also prevents flooding the stern buoyancy tank while the exhaust valve is opened.

--
Regards
Maciek

[Don Prince]

Hello Mr. Tore and Maciek,


Wow!  It looks like one dumb question has generated a lot of good information...  By the way, over night while I was sleeping I remembered the large red hand-wheel was for venting the residual water in the saddle tanks (MBT2). 


Before I retired from NCR as a hardware and software support engineer...  If I had a problem that I could not solve during the day, then I would generally figure out the problem while taking a warm shower or while sleeping.  I guess after retirement my U-Boat hobby has replaced my NCR work load; the same thing is happening again.  This stuff is coming to me in the middle of the night again!!!


I guess we just can't stop old habits...


Regards,
Don_

[tore]

Don.
It is not the first time we have figured out the working details when you have no access to drawings or further information. In fact when I was on board many detailed drawing were not available, the advantage then was on board you could start crawling around even dismantle items to make sketches for your own skizzenbuch. I wish I had mine from those days today. It is remarkable little details in the manuals available about the exhaustsystem of the Junker and on the poor old U 995 they have made a hull entrance were the piping should be. We have not yet got all the details on the outboard exhaust piping included exhaustvalve which has many parts within the pressure hull, I think I have a vague idea and shall see if I can compose a sketch within some days. In the meantime may be somebody have some drawings or photos which might give us some details. Lets hope Simon is digging himshelf out of the snow and provide us with some info.
Tore

[Don Prince]

Hello Mr. Tore,


You mean it snows where Simon lives?  Just joking of course...  Can you provide some information as to how they grind the exhaust shutting valve on the Junkers exhaust system?


Do you have any idea as to why they moved the bow buoyancy control to the control room?  There are no open slots in the buoyancy tanks, so as air escapes the water would have to pour in if opened while submerged.  Or, they open the vent to initially pump water into the bow buoyancy tank and then close off the valve.  Then they can use the trim pump to balance the U-Boat while surfaced?  Or, during a periscope attack they want a bow down angle of 1 1/2 degrees; is this how that is accomplished?



Regards,
Don_

[tore]

Don.
I don`t know why they move the bow buoyancy tank venting to the controlroom, but I guess it is more convenient to have the controls in the controlroom. The buoyancy tanks have freeflood holes in the bottom, when you open the vents waterflows freely into the tanks while diving. If the vents are open in surface position the buoyancy is gone in rough sea pitching. The tanks are not used for trimming, when ventvalves are shut in surfaced position they simply gives additional buoyancy when the bow or stern goes under the surface when pitching. You can use any tanks for surface trimming but you avoid the use of the ballast tanks. Large, partly filled tanks have a bad effect on the submarine called free surface effect, that's one of the advantages of having watercompensated fueltanks. Bow down angle of 11/2 degrees is usually accomplished by using hydroplanes.
Tore

[Don Prince]

Hello Mr. Tore,


I'm assuming they did not move the blowing valves for the bow or stern buoyancy tanks in their respective torpedo rooms.  Do you have a photo of these blowing valves?


For example, Plate 12 shows LP air is used to blow/force the sea water out of the buoyancy tanks through the open slots in the bottom of the tanks.


At what level of seas was the commander required to abandon the topside watch for the enemy because of concerns for the safety of the crew in bad weather?  An Atlantic hurricane can generate winds way above 100 MPH and really huge waves...


Regards,
Don_

[Don Prince]

Hello Mr. Tore,


I updated Skizzenbuch pages 90 and 91 with the info about the stern buoyancy tank lever and the interlock with the Junker exhaust valve..


Regards,
Don_

[tore]

Don.
LP blowing blowing of buoyancy tanks.  I don`t believe this blowing was very much used, in fact I can`t even remember them. Normally during  surfacing you left the vents open and the tanks drained nicely,I should guess in bad weather some COs would like to break the surface with ventvalves shut and then blow the tanks to to speed up the buoyancy effect. Unfortunately I cannot find any photos of the blowing valves.
The people at the bridge took a lot of beating as sometimes the sea could fill the bridge. I have experienced, particularly during the November storms, that we had to shut the conningtower hatch as we got too much water in the controlroom, once we had to navigate surfaced by the periscope and at the end we continued submerged at a depth of 50 meters. Even at that depth you could feel the swell. Thus you could have people at the bridge in quite bad weather conditions not only depending upon the wave hights, but your course  in relation to the direction of the wind and sea as well. Certainly for the Germans during WW2, not having air superiority, it was necessary to have people on the bridge under all circumstances.
Tore

[tore]

Don.
I checked your Skizzenbuch 3, OK although not yet complete on the Junker.
Tore

[tore]

Don
Junker outboard exhaustvalve.
I have looked through all my papers and cannot find any detail on the subject so I have to design the valve based on the photos available. Down below is my sketch which is an assumption/ partly shear guesswork.
The valve consist of a tube steelhousing going through the pressurehull ending in an outboard valve which connect the muffler ( sea) and the inlet ports of the Junker opposed piston dieselpart.  The valve has a free rotating valvedisc (red) and stem with a bore for the valve spindle ( yellow) on which the disc is free to rotate.
The other end of the valvespindle (yellow) has a threaded end engaging threads in the valve wheel hub (pink) which is kept in position by a rim disc in the housing. When turning the pink valvewheel the yellow valvespindle moves up and down shutting/opening the valve, the pink valve hub stays in place. As the red valvestem and disc is connected to the yellow spindle they follow the axial movement of the yellow valvespindle. At the other end of the red valve stem is a gearwheel having a hub with inside slots engaging similar slots on the red valve stem, the gearwheel is kept in place by the housing. Thus the valvestem is sliding axially in the gearwheel when the stem is axially moving by the handwheel turning.
 When the valve is shut and the sternbuoyancy tank vent is open, the Junker valve is locked by the interlock (violet) as a small cam keeps the red valvestem down (shut).
If you have to grind the valve, you shut the valve, a small shaft end protrude out of the casing as shown, and a bar is secured by a screw on this shaft and you turn same thereby rotating a worm which is engaged to the gearwheel on the red valvestem. As the gearwheel bore has slots engaging matcing slots in the red valvestem, the valvestem and valve rotates around the yellow valve spindle and you are grinding the discseat against the housing seats. The valve opens towards the seapressure and you cannot open the valve unless the sternbuoyancy tank vent is shut.
An airpipe (green)is connected to the outboard valve housing which makes it possible to blow the exhaustpipe to the sea while the exhaustpipe is shut to the Junker cleaning the exhaustpipe for water prior to opening of the valve.
I should assume it is an additional hull exhaustvalve as usual. PHU!! Confusing? read it once more and look at the sketch
Tore

[Don Prince]

Hello Mr. Tore,


I cut a segment from the aft torpedo room showing the Junker's exhaust valve...  Does it look like all three components are very close to the sale horizontal line?


Regards,
Don_

[Don Prince]

Hello Mr. Tore and Maciek,


I uploaded the latest version of Skizzenbuch to dropbox.  Page 345 contains info on Group Listening Devices (GHG, Balkon, and KDB), I also added exterior photos of Bold (Note* without the bird crap on the side and the spikes on the upper deck edge of the U-Boat.  I edited the photos!)...


Regards,
Don_ 

[tore]

Don..
When reading the page 345 I came over the photo of U 995 hanging in the big crane in Kiel at the time being converted into a museumboat page 344. At that point she had a Balkongeraet and your text  on the photo says : " showing KNM Kaura pennant no. 309 (ex. U 995) in its original configuration".
She never had the balkongeraet in my time I guess this was possibly installed at a later stage may be when she was a training/ research boat. Thus in her original configuration she was without the Balkongeraet.
Tore

[SnakeDoc]

Hi Gentlemen,

LP blowing blowing of buoyancy tanks.  I don`t believe this blowing was very much used, in fact I can`t even remember them. Normally during  surfacing you left the vents open and the tanks drained nicely,I should guess in bad weather some COs would like to break the surface with ventvalves shut and then blow the tanks to to speed up the buoyancy effect. Unfortunately I cannot find any photos of the blowing valves.

The location of the low pressure compressed air valves for blowing (bow) buoyancy tank also suggests, that blowing was used rarely.
I have attached the photo of the hull blowing valve of bow buoyancy tank - it is located 78th and 79th pressure hull (internal) frame,
over the upper, port torpedo tube - quite inconvenient place for operation.
I have also marked the valves on the aft (port side) bulkhead of the forward torpedo room. There is also one more valve on blowing
line - comparing these two photos, you can see, that it is also inconveniently located.

I was unable to locate the hull valve for blowing the MBT5, but I have attached photo presenting the MTB1 hull valve.

--
Regards
Maciek

[Don Prince]

Hi Maciek.


To make sure I understand the photos...


1. The photo with all the red arrows pointing to LP valves that lead to blowing the bow buoyancy tank.   Which valve would they use to blow the bow buoyancy tank, the hull valve, or the one down stream? Where are these valves in relation to the forward torpedo tubes?


2. The green hand-wheel is HP air and what is its purpose?


3. The photo is of the aft torpedo tube with the hull valve for MBT1 buried so deeply; am I correct?


I would imagine the hull valve for MBT5 is similarly buried in the forward torpedo room section as well. 


OK...  I have the following


1 - MBT1 and MBT5 venting valve hand-wheels in the control room
2 - The hand lever for venting the stern buoyancy tank in the aft torpedo room (VIIC/41)
3 - The hand-wheel for venting the bow buoyancy tank in the control room (VIIC/41)
4 - The info just provided about blowing the bow buoyancy tank in the forward torpedo room


I don't have info/photo of the blowing valve for the stern Buoyancy tank in the aft torpedo room...


Regards,
Don_

[tore]

Don.
I believe the green wheel valve is what Maciek says on his drawing. It acts as a shut off valve with watertrap for airbank 4. See my picture below.
Tore

[SnakeDoc]

Hi Don,

1. The photo with all the red arrows pointing to LP valves that lead to blowing the bow buoyancy tank.   Which valve would they use to blow the bow buoyancy tank, the hull valve, or the one down stream? Where are these valves in relation to the forward torpedo tubes?

I have marked the location of the hull valve on the drawing.The "down stream" valve is located on the aft bulkhead of the forward torpedo room (port side).
Which one was used? Hard to say, I suppose, that hull valve would be opened (closed only in emergency) and blowing was done by opening the "down stream" valve.

2. The green hand-wheel is HP air and what is its purpose? 

As Tore answered, this is cut-off valve for the HP air bank. Each HP air bank has similar one.
See this post: http://models.rokket.biz/index.php?topic=921.msg16560#msg16560

3. The photo is of the aft torpedo tube with the hull valve for MBT1 buried so deeply; am I correct?

I would imagine the hull valve for MBT5 is similarly buried in the forward torpedo room section as well. 

That's right.

1 - MBT1 and MBT5 venting valve hand-wheels in the control room

That's right.

2 - The hand lever for venting the stern buoyancy tank in the aft torpedo room (VIIC/41)

That's right.

3 - The hand-wheel for venting the bow buoyancy tank in the control room (VIIC/41)

That's right.

4 - The info just provided about blowing the bow buoyancy tank in the forward torpedo room

That's right.

--
Regards
Maciek

[tore]

Don.
Junker exhaust assumption.
I "redesigned" my idea a bit to match the prevailing photos. To make the system complete I studied the the coolingwater scheme showing the old system which obviously has a seawatercooled hullvalve, a simplified system of the mainengine  hull exhaustvalve. The new shut of valve to the silencer (sea) is outside the pressure hull and could be seawatercooled by the blue pipe on my systemsketch. Otherwise the sketches should be pretty selfexplaining and it only remains to repeat: these sketches are not facts they are assumptions.

[Don Prince]

Hello Mr. Tore,


I have a question about the Bouyancy tanks...


1.  Was the bow buoyancy tank above the waterline?  I remember you saying if the vent were opened that it drained quite nicely...  That would eliminate the need to crawl among the fwd torpedo tubes to get to the hull valve to blow the tank.


2.  The stern buoyancy tank looks to be partially below the water line.  If they want to run the Junkers compressor, did they need to blow the tank to get the stern higher, or just clear the water from the exhaust system?


3.  I don't recall ever seeing a drawing that shows the location of the Junkers muffler and exhaust lines outside the pressure hull.  Do you have anything?


Regards,
Don_

[tore]

Don.
I don`t have a drawing or even a photo of the exhaust silencer and pipes. But I am pretty sure it is situated at about the same level as the mainengine exhaust pipe and silencer, thus well above the surfaced waterline only the outlet probably below the watersurface. The buoyancytanks are marked on your drawing in the skizzenbuch, see my sketch below and the tanks are as you see above the watersurface having the freefloodgates just below the waterline.
 The problem is not the running of the Junker in calm weather, but in rough sea when the submarine is pitching, then the buoyancy tanks are moving under the surface and above the surface. The amount of water in the tanks increases as the bow or stern dips down in the water and decreases as the tanks are above the surface thus you have a pressure pulsation, a blowing shall not be of any use as air escapes as soon as the freeflood gates get out of the water, but the pitching is reduced by the extra buoyancy when the tanks are submerged as long as the vents are shut. Hence the interlock between the sternbuoyancy  ventvalve and the Junker outboard exhaustvalve. Before starting the Junker you could blow through the pipe and the silencer while the outer exhaustvalve  was shut as indicated on my outer exhaustvalve sketch.
Tore

[Don Prince]

Hello Mr. Tore,


Thank you for the drawing and information... 


I believe the line of green colored valves in the control room are for blowing the ballast tanks.  I remember you saying the tanks were not fully blown and they used the diesel exhaust to complete the blowing process. 


How do they know when the tanks are at say 70% empty? Do they allow blowing for so many seconds depending upon which tank?  I could see them blowing the tanks completely empty and the pressure gauge beside the distributor would drop to indicate that tank was empty and they were blowing HP air out the tide valves.

[Don Prince]

Hello Mr. Tore,


Sorry about bothering you again...  Plate 12 Shows 2 lines going to the LP blowing distributor: one is a direct line with valves but at 205 atm, and the other one has valves and a pressure reducing valve to 12 atm.


Why the two very different pressure outputs?   The pressure at around 122 meters would be approximately 12 bar.  Normally they are blowing the ballast tanks at periscope depth.  Would using the 205 kg/sq cm that equal to 201 bar ever be needed.  201 bar would be water pressure at 2.049 meters depth; the pressure hull would be completely crushed.  I know this just an exercise with numbers.  However, could the blowing distributor and its tributaries withstand the high pressure and not blow something?  If they blew the saddle tanks at periscope depth with 205 kg/sq cm / 201 atu would there be any damage?


Regards,
Don_

[tore]

Don.
The air blowing of the tanks is very much based on experience and watching the gauges and to which extent the CO want to surface on air under the prevailing circumstances. As the ballasttanks have different location in the relation to the surface they have different pressures when emptied. The normal surfacing from periscope depth is checked by the depthgauge and the CO checking the testcock of the top hatch to be sure the hatch above the seawaterlevel before he releases the hatchlocks, having the catch still engaged in view of the overpressure. If the CO want to continue airblowing, the saddletanks are watched and you are able to see air is escaping from the Kingstons. Then you continue with the MBT1 and 5, same procedure, and finally 3. As you see the tanks are blown separately in the last stage. The ideal solution would be to stop blowing the highest tank just a bit before emptied and let the air expansion take the rest when blowing the deepest tank (MBT3) but that takes a lot of experience and normally that part of the blowing is done by exhaust. The primetarget is to save precious HP air and that takes experience.
Tore

[tore]

Don.
LP air system.
A good remark, but I don`t believe there are two different pressures . The ordinary supply is the automatic reduction valve, the other connection shut. However the other connection is a back up system which has a reduction valve manually controlled, as the symbol for the supplyvalve indicates a manually controlled pressure reduction valve. You`ll find the same system used amongst several others f. inst HP blowing of the main ballasttanks. Having a manually controlled reduction/stopvalve direct connected to the HP system does not mean you are using the full pressure, it is a reductionvalve manually operated to achieve the appropriate pressure which is shown on the relevant manometer. As a safety there are reliefvalves at the end users, set at the max allowable pressure.
Tore

[Don Prince]

Hello Mr. Tore,


So, if the U-Boat was sitting on the ocean floor at 200 meters, then the 12 atm blowing pressure would be useless.  At 200 meters the external water pressure would be about 21 atm   However, if they used the manual HP air reducing valve and set the blowing pressure to 25 -30 atm, then they could partially blow the MBT3 to get them off the bottom.  Does this sound logical and doable?


Regards,
Don_

[tore]

Don.
When you are blowing the main ballasttanks  you are using the main blowing panel and having direct feeding from the 205 kg/cm2 airbanks. You are using the main blowing valve manually reducing the pressure to what is required up to 25kg/cm2. The main blowing valve has a special sharp valvecone which allows a very accurate pressure  adjustment  shown on the manometer for blowing. The blowing system has reliefvalves for each mainballast tank adjusted to 25 kg/cm2 being the pressure at designed crushing depth( VIIC/41). However the 3.9 m3 air storage  capacity of 205 kg/cm2 is not enough to empty the MBT 1,3 and 5 as you would, according to my calculation, need about 12 m3 of 205 kg/cm2 , at 200 meter you shall need appr 10 m3 of 205 kg/cm2. If you would like to blow only MBT3 incl ducts ( 47,7m3) at 200m you would need according to my calculation 4,65 m3 of 205 kg/cm2.
Thus at these extreme depths it is rather the capacity above the pressure which is the limiting factor. So I guess it is not a good idea to sit on the seabed at 200 meter and try to surface by blowing air.
Tore

[Don Prince]

Hello Mr. Tore,


I went back and checked with the "Diving Requlation Manual" that Maciek translated...


231 - 239 provides some guidance on settling and breaking loose.



"After lying on the bottom for a long time all bilges are to be pumped into the ballast
tank intended for this. The filling of all bunkers and ballast tanks is to be examined,
and the specific weight of sea water is measured for comparison.



If necessary, continue pumping with the auxiliary drain pump, in order to achieve as gentle a
release from the bottom as possible and to avoid the boat shooting up too quickly.


Blowing with compressed air to release from the bottom must be avoided because of the rising
billow of air. However if blowing can not be avoided, then it must take place in the stern,
because as a result, the boat separates more easily from the bottom than by blowing the center
ballast tanks.
 
After the freeing the boat from the bottom the ballast tanks are to be immediately flooded
again. Blowing the ballast tanks must be carried out carefully, so that inadmissible
pressures in the ballast tanks are avoided, should the flood valves lie in the mud.


239. During release from the bottom the boat is to remain bow down (at least 2°), so that
rudders and screws are not damaged. As soon as the boat is bow down and free forward and aft,
the propellers may be engaged."


So again, I was WRONG!!!  All I had to do was (RTFM) Read The Fine Manual...


Also, the blowing manifold is using HP air to blow the ballast tanks.  It all a matter of the difference in volume between the HP air input pipe diameter; the HP air volume can expand within the ballast tank lower pressure environment, and the water is pushed through the bottom open Kingston/tide valves larger exit area into the sea which provides the blowing resistance according to the depth.



Regards,
Don_

[tore]

Don.
As you correctly say  the diving manual deals with being stuck  in the muddy seabottom where you are using momentum to break loose. If we play just with volumes and pressures, Boyle- Mariottes and good old Archimedes laws are the ruling factors.
 If you blow your tanks at large depth say 150 meters, not stuck in the sea bottom and the boat is balanced to neutral buoyancy by the compensating- and trimtanks, and for some reason you want to surface by air, you don`t blow the tanks empty at that depth even if you need MBT 1, 3 and 5 empty to be fully surfaced. You blow carefully with lowest possible pressure and when the boat start to rise stop blowing as you have started a process with gradually less resistance pressure allowing the air in the MBT to expand and pushing the water out through the Kingstons as you rise. If you blow to hard, the tanks empties too quickly and you loose  air through the Kingstons as you rise. In general you would avoid such a surfacing as it is uncontrolled.
Tore

[Don Prince]

Hello Mr. Tore,



The Safety Valve settings were taken from the U-Boat Type VIIC manual published in 15.7. 40,
and do not reflect changes made to the VIIC/41.  The HP air manifold Safety Valve is set at 205 kg/ sq cm which is approximately 201.03 Bar, and the ballast tank blowing manifold air Safety Valve is set at 30 kg/sq cm (29.42 Bar).


Note, I would think the blowing air would be adjusted to 25 Bar/ ATU since all the gauges were in ATUs? That would put the blowing pressure below the safety valve setting.


Do you know is the Blowing distributor for the VIIC/41 had a different Safety Valve with a higher setting to allow blowing compressed air at a deeper depth since the VIIC/41 could go deeper?  Otherwise, If the u-boat were below 280 meters blowing compressed air would not be an option...  That Safety Valve is causing me grief!!!


Regards,
Don_

[tore]

Don.
Its hard to remember the figures, I was an EO for a VIIC/41 U995 and a VIIC  U(926) and cannot remember any different settings of the reliefvalves. The crush depth was really an extreme depth and we were never even near it. The max operational depth for a VIIC/41 was 120 m and a VIIC 100m we stayed within those limits. To blow ballasttanks at 250 or  280 meters would be a desperate emergency and I don`t believe the boat was designed for such an operation. I guess in a situation requiring a blowing at that depth,  you try anything and if the reliefvalve would blow, you adjust the valve. I feel like citing my old submarine teacher and RN commander (E): Why spend time, effort and money to learn how to escape from very rare and impossible situations, better to learn people how to operate the boat within the design limits preventing you to get into such situations. At 280meters you are lost anyhow and I guess it isn`t  worth while to worry about the reliefvalve setting.
Tore
 

[Don Prince]

Hello Mr. Tore,


As I learn more about these valves, I believe I have to go back and revisit the Negative Buoyancy tank blowing valve.  I have labeled 3 valves related to the air pressure to blow the tanks.


A.  This valve is a manually controlled pressure valve that sets the blowing pressure to 25 Bar from HP
B.  This is the red hand-wheel valve that is used to provide blowing air to the Negative Buoyancy tanks
C.  This is a pressure relief valve to limit the air pressure


See the attached drawing...  Comments?


Regards,
Don_

[Don Prince]

Hello Mr. Tore,


Can you tell me if this is correct?



High Pressure = 200+ Bar
Ballast Tank Blowing Pressure = 25 Bar
Low Pressure = 12 Bar
Negative Buoyancy Tank Blowing Pressure = 25 Bar
Regulating/FRO Tanks Pressure= 10 Bar
Regulating Tanks Pressure = 10 Bar


Regards,
Don_

[tore]

Hello Mr. Tore,


As I learn more about these valves, I believe I have to go back and revisit the Negative Buoyancy tank blowing valve.  I have labeled 3 valves related to the air pressure to blow the tanks.


A.  This valve is a manually controlled pressure valve that sets the blowing pressure to 25 Bar from HP
B.  This is the red hand-wheel valve that is used to provide blowing air to the Negative Buoyancy tanks
C.  This is a pressure relief valve to limit the air pressure


See the attached drawing...  Comments?


Regards,
Don_

Don.
The is a classical blowing arrangement for a VIIC.
  A is the mainblowing valve (red handwheel stb side) not set to any pressure but, controlled manually by the blowing man for port and stb. Q within the pressure range set by the reliefvalve C and checked by reading the manometer.
 B is not a blowing valve and has no special valvecone for pressure regulation, it is a shut off valve to the common venting and blowing pipe between port and stb. Q. This valve is shut when the system is in venting configuration.
Tore

[tore]

Don.
I am not sure I understand fully what kind of figures you want to check. There are a number of different pressures figures. Operating pressures, reliefvalve pressures, testpressures and differential pressures. Fi. the MBT blowing pressure 25 bar is not the usual blowing pressure. Blowingpressure is manually controlled to the pressure required within a pressure range I believe up to 25 kg/cm2 and I guess the max ballasttank blowing panel is having a relief valve pressure set to 30 kg/cm2. I don`t remember all the figures but I guess most of these figures are mentioned in your book U boat information translated by Maciek.
Tore

[Don Prince]

Hello Mr. Tore,
 
I was thinking again...  This setup looked like the Blowing Manifold for the ballast tanks; where there are 2 HP input lines with manually adjustable pressure valves.  A primary and a backup line in case the primary line freezes.   They reduce the HP pressure and use the individual blowing (on/off) valves for blowing the ballast tanks.  This setup looked exactly like the Q tank setup; where you could set the blowing pressure with the manually adjustable pressure valve and then use the on/off valve to blow the Q tanks.  That way you would not need to set the pressure each time you blow the Q tanks.


However, you are the expert and I am just the student who continues to ask many questions to learn about the U-Boat.  I don't believe I will ever be at the point where I don't have questions???  Thank you for the quick response...


I have just uploaded to dropbox the latest version of Skizzenbuch.


Updated pages:
90 - 91 Junkers
98 - 101 Bow and Stern Buoyancy Tanks
189 - 191 Blowing Manifold
212 - 213 Oxygen
348 Corrected U-995 Info
349 - 350 Listening Devices -  GHG, Balkon, KDB, and UT
359 added external views of Bold


Regards,
Don_

[Don Prince]

Hello Mr. Tore,


I was looking through my photo files and I noticed several things about Kaura / U-995....


The photo at with the mountains in the background; there is no lower gun deck, only the upper one.  Was that removed when it became the Kaura S309?


There is a photo of Kaura with people lined up and assending the stair case to the stern hull entrance.  In addition, there is a Norwegian flag on the pole beside the stair case.  Was Kaura a museum boat before it went back to Germany?  It surely looks so...


Regards,
Don_

[tore]

Don.
When the Norwegians introduced the VIICs and VIIC/41 submarines as Nato subs. their operation would be different from the germans. The AAguns or foredeck gun would not be necessary, in addition the boats had schnorchel and spent more time submerged. The guns and wintergarden created a considerable drag submerged, reducing the underwaterspeed. So we removed both the wintergarden and guns and designed a new aft towercasing. It is not a copy of the old VIIC tower from the 1940/41 as can be seen on the photo below.
U 995 museum.
I assume the photo you are referring to is the one below. The U 995 was never a museum in Norway,after my time on board she had a refit and was not used as a frontline sub.any more, but more like a training and research vessel before she was faced out and laid up, I guess in 1962. As from 1965 there were confidential talks and plans to return the submarine to Germany as war memorial. It took a long time before it became a reality as it was still a touchy subject still close to the war. In the early 70ties she was converted to a museum in Kiel and the official handing over sermon took place at Laboe October 2nd. 1971. the photo of the event is below.
Tore

[tore]

Don.
 I have checked you Skizzenbuch (5) and have a few small remarks.

There is a misprint in paragraph 1 mentioning bow buoyancy tank instead of stern buoyancy tank.
On page 101 you have a double description of the Junker which is a bit confusing in addition it has become a two cylinder diesel. The correct text would be: The Junker compressor is driven by a single cylinder opposed free piston, two stroke diesel............
The whole Junker exhaustvalve arrangement is an assumption as we have no original drawing or description of  the design.
Tore 

[tore]

Don .
The venting system of a submarine is one of the most important systems and I just had a look into your description of the system in your Skizzenbuch. On page 281 it seems to me that you have mixed up the MBT 3 emergency shutoff ventvalves with ordinary vents. I have made a sketch based on Plate 16 and 28 below which give an explanation of the system.
The venting of MBT 3 is done via two ducts going through the port and stb. regulating tank and then outside the pressurehull to the port and stb main ventvalves operated from the controlroom. The saddle tanks 2 and 4  have a similar arrangement however the venting ducts goes directly outside the pressure hull and  2 and 4 stb merge into a common ventvalve as port tanks do as well. In the ducts, at the point where these ventducts leaves the tanks there are emergency shut off valves which normally do not take part in the venting of the tanks, they are normally always open and only used in the event of a damage to the outside duct.
A third valve is placed in the MBT 2 and 4 ducts, coloured green on the drawing. These are the isolating gatevalves, shut when the saddletanks are in fuelconfiguration. Otherwise they are always open.
Tore

[Don Prince]

Hello Mr. Tore,


Is that page 281 of the current Skizzenbuch file loaded into dropbox currently?  Almost every time I make changes, the page numbers change.  Currently Page 281 just contains drawings from u-historia about the MBT 2 and MBT 4 hull valves, and the MBT 2 dual residual valve and hand-wheel in the control room.


Page 282 deals with MBT 3 and the commom trunk valve that is operated via a lever in the control room which is also from u-historia.


Regards,
Don_

[tore]

Don.
Yes, I believe you have copied the drawings and may be the text. What is confusing is probably that the emergency shut of valves are called vent valves, giving the impression that they are used in the normal tankventing operation, whereas they are practically never used for venting. They are emergency valves. See drawing below.
Tore

[Don Prince]

Hello Mr. Tore,


I am not permitted to change their drawings, byt I will add a note about the errata.  I will poat a new Skizzenbuch late this evening which will have 10 additional pages as well...


Regards,
Don_

[tore]

Don.
As the emergency valves  have a purpose in the system it is absolutely worth while to explain. A ventpipe outside the pressurehull only hidden by a fragile casing is very susceptible to for inst. aircraft machinegunfire, a puncture of a ventpipe shall cause all the air to escape from the ballasttank which might have a serious consequence that's why these valves are important yet very rarely used.
Tore

[Don Prince]

Hello Mr. Tore,


Thanks for the explanation...  I just assumed the valves were redundant vent valves.  I sure am getting an education!


Regards,
Don_

[Don Prince]

Hello Mr.Tore and Maciek,


I uploaded to dropbox the latest version of Skizzenbuch with the following changes:


Plate 17: Blowing pages 190 - 199
Plate 21: Sanitary Systems pages 226 - 227
Page 291 - Emergency valves
Page 295 - Drawing of valves and locations
Page 327 - Toggle Switchboard


Regards,
Don_

[tore]

Don.
I checked your latest Skizzenbuch and have a  few remarks. Plate 17 page 190-199 on the blowing distributing panel you have omitted the branch no 11 being the supply to the blowing panel for the regulating fo.tank and the Q tanks. On page 197 emergency blowing is just a minor thing, referring to a geographical area as the eastern sea, I guess it should be the Baltic. I  have made a sketch of the venting system of MBT 3 showing the valve arrangement and the venting ducts going through the port and stb. regulating tanks.
Tore

[Don Prince]

Hello Mr. Tore,


Originally, I had an item No 11 for the blowing manifold...  I thought it was strange; the U-Boat Manual had an item 11, but only 10 in the drawing....  So, I deleted the 11th entry.  Now, I put it back...


Regards,
Don_

[SnakeDoc]

Hello Gentlemen,

Originally, I had an item No 11 for the blowing manifold...  I thought it was strange; the U-Boat Manual had an item 11, but only 10 in the drawing....  So, I deleted the 11th entry.  Now, I put it back...

the item 11 is hard to notice - I have marked it with red circle.

--
Regards
Maciek

[Don Prince]

Hello Mr. Tore and Maciek,


I looked at that blowing manifold many times and missed item 11.  Perhaps I need to get those cataracts taken care of very soon!


I uploaded a new version of Skizzenbuch to dropbox this morning...
Page 292 -  Tore's MBT 3 Drawing and info
Page 192 -  added item No 11
Page 197 -  changed to "Baltic"
Page 199 -  added Bordabschlusse und Klar Tafel - or light panel (info from Maciek)


Regards,
Don_

[tore]

Don.
I have checked you last update of your Skizzenbuch and it seems to be OK. Only a few minor remarks ( Can`t resist. ) You have changed to Baltic one place but East Sea is still in the text. I believe the east sea nomination derive from that we who lives near the Baltic usually call the Baltic sea for the East sea, but in English I guess Baltic  would be the correct name.
You are using the word close when you are referring to items to be shut. In Royal Navy submarine English one of the first ting you are told is, never use the word close, always shut. The reason is that for a vital word on board a submarine like shut there has to be only one word for shut, any other word is forbidden to prevent misunderstanding or confusion. I am not familiar with the US submarine customs.
Tore

[Don Prince]

Hello Mr. Tore,


I fixed the one East Sea to Baltic Sea.  In addition, I did a WORD search and replace on the word "close, and closed" and replaced them with "shut"... 


I believe this will close (OOPS.. SHUT) the issue.


Latest Skizzenbuch was uploaded to dropbox.


Kind regards,
Don_


PS - if close or closed is in a drawing image, than that will remain because WORD can't read images.

[Don Prince]

Hello again Mr. Tore,


I went through Skizzenbuch and I believe there were 6 images with the word/words "closed" in them.  I went to my images folder and modified the original images and pasted them into Skizzenbuch.  So, I believe all instances of "closed" has been removed form the latest revision of Skizzenbuch, and it's in dropbox...


Regards,
Don_


PS: So far I have learned two words; SHUT and SCHNORCHEL...

[tore]

Don.
What a relief, now we don`t have a disaster by giving unclear orders.
I just noticed you have in your Skizzenbuch some interesting photos on the HP blowing and exhaustblowing of the main ballasttanks. I have put same up to show a typical surfacing procedure.
To the left is the controlroom engineer  blowing all the main ballasttanks having his eyes fixed on the blowing manometers ready to shut the main blowing valve when the order from the CO is stop blowing.
The next photo shows the controlroom engineer again having his eyes fixed on the manometer adjusting the exhaust gas pressure for MBT 1 and 5 which means he has finished blowing 2 and 4 saddletanks ( if not in fueloil configuration) and is ready to switch over to MBT3 as soon as 1 and 5 are empty.
Tore

[tore]

Don.
Referring to your latest Skizzenbuch I shall just mention a couple of beautyspots. Page 76 explanation of a gatevalve. The gate valve, particularly those used as isolation for the ventducts of fuelballasttanks 2 and 4, are more like a substitute for blindflanges. The advantages above a blindflange is they are easier to shut than putting in a blindflange. Yet ,when not in use, they have the "gate" out of the way thus no obstruction in the pipeflow. The construction is as can be seen on my picture below. The use of a inboard ventilation valve may be a bit misleading for an outboard gatevalve as the ventilation valve has a different shutting arrangement.
A very minor remark. On page 251 you are correctly referring to type XIV as a Milk Cow, however the German name is Milch Kuh and not Kul.
Tore

[Don Prince]

Hello Mr. Tore and Maciek,


I corrected the spelling error for 'Milk Cow" - Kuh


I added Mr. Tore's rendition of the two crewmen using the blowing valves and removed the two lone photos.  That way I don't need to change the page numbers and the index.   The latest version of Skizzenbuch is in dropbox.


Also, I uploaded a new folder "U-Boat Museum" which contains about 40 images of wiring / e-motor / speed controller information.  Mr. Tore, you are welcome to what's there...  Maciek has access as well.


Regards,
Don_

[Don Prince]

I re-sized the files in the U-Boat Museum folder to 8.5 x 11.75 to get rid of the blank space and rotated the files to be up right...


Regards,

Don_

[tore]

Don.
Where do I find your U boat Museum folder? Dropbox? It is not yet there as far as I can see.
Tore

[Don Prince]

Hello Mr. Tore and Maciek,


Sorry, I just assumed since you had access to the Skizzenbuch folder that you would have access to everything under the folder.  I just sent you all a link to the U-Boat Museum folder,


Regards,
Don_

[tore]

Don.
Got it looking forward to reading it, Working on scanning the high voltage scheme.
Tore

[tore]

Don.
Your Skizzenbuch is increasing in volume yet there are further items to consider worth while  to be included.
The VIICs are equipped with possibly one of modern technology`s last and most advanced use of mechanical transmissions. Hundreds of links, rods , traveling nuts, bearings and bevelgears installed required a substantial maintenance for safe operation. Greasing and lubrication is one of the major factors. The greasing system consist of two major greasepumps with container, one  A situated in the engineroom stb aft side next to the main engine clutch handle, the other B, in  the forward torpedo compartment stb side just aft of the torpedotubes ( next to the visitor door on museum U 995). From these grease pumps pipes goes via a hullcock through the pressurehull to a selector/distributor and then to various difficult spots outside the pressurehull. The outboard selector is controlled by a handle inside the pressurehull as can be seen on my sketch below. Please note the details on the construction are assumptions from my side as no drawings are available.
Further to the system are grease cups practically fitted everywhere there are moving parts,  travelling nuts would have a flexible grease hose as can be seen on the Kingstons on plate 28. Most of these Kingston greasing spots are fed by greasecups in the control room. Many of the grease cups of the museums U 995 are gone, only some pipes and under parts of the grease cups remains.
The system was extensive and labour consuming and we had a PO responsible for the weekly greasing routines.
Tore

[tore]

Don.
High voltage scheme.
I have finally been able to scan the high voltage scheme the original, as I told you, is pretty shot. Before I continue, could you make use of this quality? I am afraid the original isn`t much better.
Tore

[Don Prince]

Hello Mr. Tore,


I believe these greasing pumps are hand operated and not electrical, am I correct?


Regards,
Don_

[tore]

Don.
As far as the greasepumps concerns they were handoperated, you clearly see the handles on the photo below. The lubricators (Gruetzner) were rod driven by the main engines. These lubricators were supplying oil droplets to points were the dieselengine main luboil system could not be used. They a pretty easy to locate up front of the engines inboard port and stb.
Tore

[Don Prince]

Hello Mr. Tore,


Thank you for the quick response...  I updated Skizzenbuch and the "Maintenance" section is on pages 262 and 263, and it's in dropbox.


Good night, it's 2:20 am here in Georgia.


Regards,
Don_

[tore]

Don.
Checked Skizzebuch 10 page 262 and 263, OK.
Tore

[Don Prince]

Hello Mr. Tore and Maciek,


After going over some of the switchboard schematics from the U-Boat Museum, I realized I was confusing the Dead Slow speed with the single switch option Crawl or Creep speed.  This may have been an option on the older switchboards, but the current manual schematic we have it looks to be disabled.  Craw or creep would have put the speed at around 30 RPM (around 0.8 knots).  I guess the Germans needed more speed while submerged, and not less...


Mr. Tore have you ever heard of the creep or crawl speed while submerged in Kaura?  I guess Maciek will be glad I have finally seen the light!!!  I have up loaded a corrected version of Skizzenbuck into dropbox,


Regards,
Don_

[tore]

Don.
I never heard about creep or crawl speed submerged, apart from dead slow we had silent running.
Tore

[Don Prince]

Hello Mr. Tore,


I have a question about "Plate 6:".... The Main Drainage Pump can pump water into a drainage port or MBT 3.  Both end up sending the pumped water into the sea because MBT 3 has the flood valves open and the air pressure will force added water out the open flood valves (Kingstons) while surfaced.  Then again while submerged any water pumped will end up into the sea as well.  So is the drainage port redundant?


Regards,
Don_

[Don Prince]

The only thing I could forsee is if some of the blige water had oil.  Then it could be pumped into MBT3 so not to leave an oil slick.  The oil would remain in MBT3 floating on top of the water residual.


Don_   

[Don Prince]

Hello Mr. Tore,


I believe Silent Running was a test ran to determine which speed produced the least amount of noise.  Was that done with one prop or two?


Regards,
Don_

[tore]

Don.
Your assumption of the use of bilgewater outlet into MBT 3 is correct.
Tore

[tore]

Don.
Silent running was not a testrun. It was an order given to be as silent as possible trying to eliminate cavitation noise ( propellers), crewnoise and shutting down noisy auxiliary machinery. Once a year we had noisetrials laying semi submerged surrounded by microphones, starting up each axillary machinery one by one, recording the noise to establish the noisepattern in view of which items could be run under silent running condition, a kind of noise certification. You could run both propellers or one depending upon you noise pattern, (Cavitation)
Tore

[Don Prince]

Hello Mr. Tore,


On Page 82, where the crewman is using a claw tool to change the ballast tank configuration.  If the hand-wheels were removed from the gate valves, then would the claw tool still do the job or would he have to use a different tool?


Regards,
Don_

[tore]

Don.
The tools you mention were not only tools for the fueloil / ballasttanks configuration, but used for many type of valves. What you call a claw tool is a valve wheel wrench used on valves having wheel and hard to move. The other tool is a T bar extension tool used on valves  having no wheel and which could have an extension up to the deck ending in a small square supported by a connection in the deck or simply a valve deep down without a wheel or lengthening rod. In the case of the gatevalves for fueloil/ ballast tanks 2 and 4 they would act as blindflanges, very seldom used and as such I guess most EO would like to remove the wheels using T bar extension to reach the valves. If you look at the picture below you shall see permanent valve extension to the  in the deck for valve frequently used. For these connections you used the T- bar as well.
Tore

[Don Prince]

Hello Mr. Tore,


I added a maintenance section to the index and to Skizzenbuch.  Also, I added 2 pages to the torpedo section to get a better explanation of the firing valve and pilot valve, and I went through the complete book and corrected any wording or spacing errors.  Just about completed except for a page or two on the speed controller later...  I believe Skizzenbuch is getting very close to finished.  Also, I uploaded the latest version of Skizzenbuch to dropbox


Regards,
Don_

[tore]

Don.
As you are about to finish your Skizzenbuch I would like to mention a last item worth while to include, the clutches and the shafting system.
 In addition to the clutches described in the emergency manual operation of the hydroplanes, there are several clutches in the shafting system as well as clutches in the Roots blower of the GW engines.
The main clutches between the main engines and the E-motors/generators are double cone friction clutches pneumatic hydraulic operated and I have made some sketches and photos previously on this thread.
The double cone tail clutches, manually operated, are situated just after the E-motors/ generators and the Michel thrust bearings.
The Roots blower clutches are situated in the aft end of the main engines having  maneuvering handles extended to the maneuvering stand up front towards the pressurehull sides. The rods of same are  connected to the aspirated air inlet shut off valves and interlocks as well.
Tore 

[tore]

Don.
My description of the pneumatic/hydraulic clutch between the main engine and E-motor/generators can be seen on page 88 and 89 on this tread.
Tore

[Don Prince]

Hello Mr. Tore,


You are correct and I will add the clutches. Do you have any good photos of the back end of the Diesel engines with the clutches?  I believe the drive was both manual and hydraulic???.  I pulled a photo from u-historia and they show the e-motor clutches and levers to engage.  Was this only manual for the e-motors?


Also, there is a photo of the diesel engines from the back and there are three hand-wheels shown.  My guess is the two large ones are for manually engaging the diesel drive shaft clutches...  How do they engage the Supercharger clutches and I believe they are engages while the diesel engine is running.  I will post the photo.


Regards,
Don_

[tore]

Don.
The only pneumatic/hydraulic operated clutches were the two between the main engines and E motors/generators. As an emergency alternative they could be operated manually by the wheels shown on your photo my sketch below shows how they works. If you need further explanation just ask. The third handwheel (small) has nothing to do with the clutches and belongs to the ventilation system.
As to the clutches for the Roots blower they are operated manually from the maneuvering stand up front of the engine. However on your photo you see the casing of the clutch
just below the blowercasing. As there are interlocks and other elements in the manual operation of these clutches I shall revert to that system in a different post. You are right in your assumption that the Roots blower is connected while the diesels are running.
Tore

[tore]

Don.
The clutches for the Roots blower on the GW engines have to be interlocked for several reasons, for the direct reversible engine an interlock is needed to prevent the clutch to be engaged when the maneuvering handle is in astern position, for both reversible and nonreversible engines it is an interlock preventing the clutch to be engaged when fuel handle is in a position corresponding to, at normal load, the enginerevs are below 420 rpm. At the same time the normal aspirated inletair ducts have to be shut when the Roots blower is engaged.
All these functions are obtained via linkages from the manual clutch lever up front of the mainengines as can be seen on the drawing below. There is a slight deviation between the basic arrangement for the direct reversible and non reversible engines. The maneuvering diagram shown is a direct reversible execution. The Roots blower drive is a PTO of the camshaftdrive and having a wrap spring coupling for torsional vibration reasons and a double cone friction clutch as can be seen on the drawing. In order to save the friction lining of the clutches, you would like to engage the clutch at lowest possible revs as the inertia forces caused a heavily wear on the friction lining.
On the MAN engines these clutches were not needed as the turbocharging ( Buchi system) could operate during the whole rpm range as well as astern.
Tore

[Don Prince]

Hello Mr. Tore,


I have a question about the distribution cock for the pneumatic-hydraulic system...  Should the cock be a change-over cock with a central passage type valve?  My reason for thinking this way;


If the non active cock position provided a path to both pressure flasks so if the pneumatic-hydraulic system failed, then the hand-wheel could be used and it would move the piston via the worm shaft nut and easily move the hydraulic fluid from one side of the piston to the flask with no air compression.  There would be no back pressure???


What do you think?


Don_

[tore]

Don.
If you study the systemsketch you shall see the central passage is already there and the handle for the pneumatic/hydraulic system has three positions: In, Out and Neutral, the latter position allows the hydraulic fluids as well as the confined air to shift as there is no volumechange (external air supply) while in manual (neutral) operation position.
Tore

[Don Prince]

Hello Mr. Tore,


Thanks for the response...  Would the valve cock handle be spring loaded to return back to the neutral position connecting the channel between the two flasks?  That way if there were a failure of the Pneumatic-hydraulic system, then the manual operation would not require any distribution cock lever change?


Regards,
Don_

[tore]

Don.
The handle for the pneumatic/ hydraulic system is springloaded but only to lock the cock in the selected position, the lock is released by pushing the knob on the top of the handle. In the unlikely event of loosing the pneumatic pressure and it was vital to have the clutch engaged, I guess you could keep the clutch in position by moving the cock as indicated on my sketch however  this was not a standard position. I never tried it.
Tore

[Don Prince]

Hello Mr. Tore,


I wrote a section "Drive Propulsion Systems.pdf" and it is now in dropbox.  I quit building pages in the 3 Skizzenbuch sections because of file size.  I'm just guarding against file corruption this late in the book write-up because of MS Word problems with large files.


If at all possible would you please check the 8 pages?  And make any suggestions that you believe is needed.


Kind Regards,
Don

[tore]

Don.
I have read your 8 pages which seems to be OK apart from a couple of obvious misprints. It looks as if you have copied some old manuals as to the various diesel  operations as there are no mentioning of the alternative schnorcheloperations which you have described in your Skizzenbuch previously.
I guess a more extensive explanation of the thrust bearing would be worth while. The thrustbearing is a Michell ( pronounced Mitchell) type of bearing having thrustpads on both sides (ahead and astern) of a forged (intergrated) disc on a shaft stub which turns in ordinary slidebearings. The pads have whitemetal slidingsurfaces towards the disc and a ridge or knob on the backside able to tilt the pad, creating a wedgeshaped oilfilm between the thrustpad and the disc during rotation. The bearing has a selfcontained lubrication system with an oilsump which is watercooled either from the central cooling pipe or from the compressor coolingwater pump, see my sketch. Red is pressureline, blue is discharge. The bearing housing has a sturdy foundation secured to the pressure hullstructure (red) able to absorb the thrustforces to the submarine. Kindly note that the British version of coolingwater plate 13 is not correct on this point, the original German is OK. Aft of the bearing housing is a PTO to the propellershaft revs counter.
Tore

[Don Prince]

Hello Mr. Tore,


Thank you for the info on the thrust bearing...  I updated Skizzenbuch and the Propulsion Drive System starts at page 352...  The latest version of Skizzenbuch is in dropbox.


Regards,
Don_

[tore]

Don.
I checked your latest Skizzebuch page 352 OK. However I accidentally discovered on page 312 and 313 you have two almost identical drawings of the MAN reversing system. In your cramped space I guess only one drawing of the system is sufficient and page 312 has the best copy. On page 308 and 311 you have the same for the GW engine page 308 best.
Further you better check page 315 and 317 which has the same crossection drawing as well as page 314 and 316 which alltogether would save you some 4 pages.
Tore 

[Don Prince]

Hello Mr. Tore,


Those duplicate plates were intentional...  There are the plates with some English notation and there are the original plates with only German text.  I have done this throughout the book with the English index and the pure German indexes, and the English noted plates and the pure German plates.  It was sort of a verification of the information presented to the reader.


This duplication has definitely increased size of the book.  If the book is ever published, then perhaps the publisher may want to remove the German-English duplication.  For my own personal view this will stay for when I commit it to print my one own personal copy and place the pages into my black leather covered metal post binder.  That post binder cost me just over $245 USD and is expandable to any number of pages.


Thank you for noting the pages...


Kind regards,
Don_

[tore]

Don.
I guess your Skizzenbuch shall be some book. Be aware of that some of the translated copies of the system plates have some mistakes both with regards to the text and the sketch particularly with regard to pipelines crossing. Re: cooling waterpipes thrustbearings and cooling waterpipe spare cooling waterpump main engines.
Tore

[Don Prince]

Hello Mr. Tore,


When I look at the Papenburg depth gauge between the two control stations in the control room, it looks like the gauge is in two parts.  The forward water column looks to indicate the height of the periscope to a point.  Then the aft water column on the right looks to indicate the periscope head/eye at a position above or below the water surface.  Is this basically correct?


The question I have is this gauge is in the control room, and the captain is in the tower working the attack periscope.  Does the captain use/need the Papenburg depth gauge.  I would not think an experienced  captain would need the gauge because he could see when the periscope is above or below the water.


I don't recall any linkage between the periscope pneumatic-hydraulic drive and the Papenburg depth gauge...

Also, what is this device on the other end of the control room.  It is two long tubes with a perforated metal protective covering?  See photo...


The huge 0 - 25 meter depth gauge; what are the reference points? At 25 meters is that to the surface from the bridge, deck, keel?  If it were the keel, then it could never get to 0 meters...

Regards,
Don_

[tore]

Don.
The two long tubes with the metal covering are the level gauges for the port and stb fuel/ regulatingtanks (saddletanks) 1 and regulating tanks 2, you have 2 on each port and stb side.
All the depth gauges shows the depth from the keel bottom to the surface and the large depthgauge to 25 meters was used to navigate at periscope depth.The only time the gauge show 0 was in drydock   It was shut off when going deeper.
The Papenberg depth gauge is important as some time during attack you might have difficulties in keeping stable depth, thus the periscope which should not be too heavily exposed would require a constant adjustment while CO is busy with bearings and other attack parameters. I guess he could leave that adjustment to another periscope adjustment station next to a Papenberg depthgauge. If you look at the hydraulic system for the tower you are able to locate two control levers for the attack periscope one locally at the periscope and one off the periscope having a selectorvalves to choose one of the two. I guess on some of the IX types you had an indicator connected to the winch which gave, combined with the Papenberg, a direct indication of the periscope exposed above the surface. I can`t remember this device on the VIICs.
Tore

[tore]

Don.
The Papenberg depth gauge, named after the inventor, a German naval engineer Heinrich Papenberg (not Papenburg)  is used for a quick response and accurate depth control at shallow depth for different purposes like accurate periscope depth and schnorcheldepth. It is a watercolumn gauge having connection to the sea via shut off valves on one side and a sealed aircushion on the other side. The scale could variy like having a sketch showing the depth in relation to the schnorchel mast floatvalve or the periscope. The sketch shown below shows the navigation periscope position and I think the air inletfloat of a ringfloat schnorchel mast. I guess in the tower it would be the attack periscope.  As far as I remember you had to shut the hullcocks at 18 meter.
Tore

[Don Prince]

Hello Mr. Tore,


I uploaded the latest Skizzenbuch to dropbox and the info on the Papenberg gauge is on pages 183 - 186...


Thank you for all your help!


Regards,
Don_

[tore]

Don-
I have checked your skizzenbuch pages 183 and 186 and have a few remarks. I realize I forgot the inclinator gauge next to the Papenberg, this gauge is called the inclinator and works as you describes, the advantage of this design is that it is more accurate and easier to react on than a conventional air bubble in a curved glasstube. The instrument showing the shaft rpm is called a tachometer. The small manometer next to the 25 meter depth gauge is not the main depthgauge for larger depth, it is a check manometer for the depthgauges. I am afraid somebody nicked the big depth gauge for the larger depth on old museums U 995, but on the photo below you see the depthgauge we used at depth exceeding 25 meters.
Otherwise the pages are OK.
Tore

[Don Prince]

Hello Mr. Tore,


I made the corrections to Skizzenbuch and uploaded the latest version to dropbox,,,


Also, a welcome back to Maciek from his vacation (Holiday), I hope it was pleasant and relaxing my friend...


Regards,
Don_

[tore]

Don.
Your Skizzenbuch checked OK except I believe a few words have been omitted on the deep depth gauge as you state :"  when the submarine is running at depth submerged ...."   It is used for depth beyond 25 meters.
Tore

[tore]

Don.
Direction of propellerrotation.
The opposite direction of the propellerrotation is not unique for a submarine, but counter rotation ( usually outboard rotation) for a twin propeller installation is normal for any ship having twin propellerinstallation. The reason for such a counterrotation is that the torque created by each propeller is neutralised. If both were rotating the same direction, the vessel would drag to one side which  constantly had to be compensated by the rudder and you would have a loss of energy (speed).
Tore

[tore]

Don.
As a professional in electrics I wonder if you have noticed the two way of cabling on the museum U 995. The neat original and the post war type. We have many times warned against copying the details in this submarine as many details are not original. The fluorescent lightning was of course not original as well as the postwar cabletrays running right through the whole interior. In the engine room these trays are an obstruction for pulling a main engine piston and the watertight bulkhead passages are just plain holes as can be seen on my photo below.
Tore

[Don Prince]

Hello Mr. Tore,


Thank you for noting the cabling...  I believe I will add that to Skizzenbuch.  In Addition, Maciek has provided me with a great deal of information after his Holiday and I'm working on that as well.  It will take awhile before the next version of Skizzenbuch is available.


Regards,
Don_

[tore]

Don.
Your Skizzenbuch seems to be a never ending project. Today I just mention a simple yet important detail in the structure strength of the pressurehull. The two torpedoloading hatches creates a large oval hole in the pressure hull which implies a cut of two frames causing a severe weakening of the structure. This is compensated by introducing two strong removeable supportbeams which substitutes the cut away parts of the two frames. Sometimes during a long stay in harbour we used the forward torpedo hatch as an easy access and we removed these beams not just for the torpedoes but even for the crew and guests.
Tore

[tore]

Don.
In your Skizzenbuch page 48 and 49 you state  the measuring tubes for both the regulating tanks 2 and the fueloil/regulating tanks 1 are for measuring fuel in the tanks.
 As you know the regulating tanks 2 port and stb have only water for compensating weight changes, you need that capacity just for regulating water and thus cannot be used for fuel, whereas the smaller fueloil/regulating tanks no 1 port and stb. can be converted to fueloil tanks. The water gauges for both tanks are primarily used for accurate measuring the water contents, but can of course for fueloil/ regulating tanks no 1 port and stb. be used for fueloil measuring as well.
Tore

[Don Prince]

Hello Mr. Tore and Maciek,


I just went through a major update to Skizzenbuch...  I changed the font size (smaller) on the 2 index pages so I could have more entries.  I have made the following updates:


48 - 49  fuel / Water  Per Tore and Maciek
84  Tools  Per Tore
92 - 93  Junkers exhaust  Tore
115  Aux water cooling  Per Maciek
136  Aux lubricating Pump  Per Maciek
183 - 190  Panenberg, Inclinometer, Depth, Tachometer, Telegraph  Per Maciek
265 - 259 Periscopes  Per Maciek
282 Torpedo Tube Hatch  Per Tore
352 - 353 Rotary Converters  Per Maciek
354 Update Rotary Schematic  Per Don_
366 - 374 Propulsion and Clutches  Per Tore


I placed the latest version of Skizzenbuch in dropbox and I do welcome comments...


Regards,
Don_

[tore]

Don.
 I have read through the Skizzenbuch pages mentioned by you and have following remarks.
Page 48-49. Fueloil bunker and regulator tanks 1. You use the expression "air is blown into the pressure hull". You are actually venting the tanks into the control room. As these tanks, when used in fueloil bunker configuration, are not connected to the compensating water system and as such have to have another transfersystem, LP air is used for the transfer. The tanks are vented trough sightglasses and muffler into the controlroom bilge.
Page 4 "T" tools you mention "....have a square socket to fit over the deckdoor screw down lock of the....". Many (most?) of the valves have an elongation of the valvespindle ending in a square up to the deckplates for easy access by the T tool. Thus no "doors" or hatches needs to be opened, see my photo of the engine room and casingdeck.
Page 92-93. As the Junker compressor is a free piston two stroke diesel it is very susceptible of accurate balancing. It is a single cylinder engine, not two cylinder as stated. Having carbon deposits on the opposed pistons due to bad scavenging and combustion creates pistoncarbon deposits (unbalance) and shorten the maintenance intervals, thus increased exhaust counter pressure should be avoided.
May be you should emphasize that the Junker exhaustsystem sketches made by me is an assumption from my side as we have no original drawings of same.
Page 136 Aux. luboilpump. The pump you describe is the fueloil transferpump which can be connected to the luboilsystem and thus used as an auxiliary luboil pump.
Otherwise  I enjoyed quite a few interesting, unknown to me, photos- Macieks ?
Tore

[VIC20]

Tore, look at this lol: https://www.youtube.com/watch?v=MzA1brBuhFc