Author Topic: Tores mailbox VIIC and VIIC/41 operation and technical details (Read 655358 times)

tore · « **Reply #2800 on:** 26 Jun , 2015, 14:25 »

Don.
There are several images of U 995 repairing the casing, however these are photos of the renovation of the museum U 995 end of the 60 ties in Kiel when they removed practically all the pipings and ducts inside the casing prior to making the museum boat. In 1953 after the severe casing damage we ended up in Londonderry and got a temporarly repair carried out on the casing alongside a RN submarine repairship where upon we were able to take part in an execise using the MBT 3. I don`t think we ever took a picture of the damage. Coming home they evaluated the damage with regards to the permanent repaircost and came to the conclusion that a permanent repair would be worth while after all.
Down below is a photo of the renovation of the U 995 in Kiel around 69-70, as you see they pretty much cleaned out everything inside the casing. I guess your photo is from this renovation.
Tore

Don Prince · « **Reply #2801 on:** 26 Jun , 2015, 17:11 »

Hello Mr. Tore,

I assume you meant... "a permanent repair would NOT be worthwhile after all."

Regards,
Don_

Don Prince · « **Reply #2802 on:** 26 Jun , 2015, 19:10 »

Hello Mr. Tore and Maciek,

I believe I have completed the MS Word Master Vision (spelling and grammar check, and art lay-out) of Skizzenbuch 11 x 17 - M for Schiffer Publishing. This version is a guideline for what the lay-out for the book should look like as proposed by me. The next phase would be to do the layout for the publishing printer which is so different and special character based.

However, I still retain the option to change the Master if there are still corrections to be made.

I have uploaded the latest version of "Skizzenbuch 11 x 17 - M" to dropbox...

Again, I really appreciate all of your help with this project, and I could not have done it without your help!

Kind regards,
Don_

tore · « **Reply #2803 on:** 27 Jun , 2015, 00:44 »

Don.
No Don, the damage was that big that voices were raised to scrap the submarine, but after a thorough evaluation the navy decided to carry out permanent extensive repairs. but after this event she was taken out of service and became later a training submarine and the active crew including me got another VIIC, KNM Kya ex U 926 being only sligthly different from the VIIC/41.

Still some 50-60 pages to double check, however my computer is about to give up, it looks as if some of the prossesors are gone, so I have ordered a new one which shall be ready next week.

Tore

Don Prince · « **Reply #2804 on:** 27 Jun , 2015, 11:36 »

Hello Mr. Tore,

OK, I will hold off in presenting a final Wprd document to Schiffer... Thanks for the update.

Regards,
Don_

Don Prince · « **Reply #2805 on:** 27 Jun , 2015, 12:07 »

Hello Mr. Tore,

Do you remember what year you was transferred to Kya?

I know about computer problems... I plan on getting a new computer after the 1st of the year. My dual processor 3 Giga Hz DELL XPS700 is about 9 years old and ready to be donated to the St. Vincent De Paul Charity...

Regards,
Don_

tore · « **Reply #2806 on:** 27 Jun , 2015, 12:31 »

Don.
I was transferred to KNM Kya ex U- 926 early 1954.
Tore

tore · « **Reply #2807 on:** 27 Jun , 2015, 12:44 »

Don
I have a HP pavilion dv7 which is a high performance PC having a intel core i 5 prosessor 4 years old. The problem is, in order to keep the price down they sacreficed a lot on the components and the PC is very easy overheating resulting in the prosessors are damaged.
Tore

Don Prince · « **Reply #2808 on:** 27 Jun , 2015, 17:31 »

Hello Mr. Tore,

I uploaded the latest version of Skizzenbuch 11 x 17 - M with your info about U-995 on page 339.

Regards,
Don_

Don Prince · « **Reply #2809 on:** 29 Jun , 2015, 00:53 »

Hello Mr. Tore,

I sort of did a face lift on Skizzenbuch... I corrected the titles to present the correct German and English listing. I removed any reference to Plate, and Diving Plane was changed to Hydroplane.

I have up loaded the latest version of "Skizzsnbuch 11 x 17 - M" to dropbox.

Regards,
Don)

tore · « **Reply #2810 on:** 30 Jun , 2015, 07:58 »

Don.
I am struggling a bit working only with one prosessor and am afraid I have to posponed my remarks until I get my new computer. However I discovered an important detail in your comments on the Junker compressor page 97 in the latest Skizzenbuch. As to the U 570 compressor you mention : .....the airintake was definitely cleaned up and takes less space.....
I guess you have misunderstood the cross section drawing. As I mentioned in my reply post 2494 feb. 27 I did not have a proper crossection Junker drawing so I used the crossectiondrawing of a Japaneeze (Kobe steel) Junker execution which, although having a different airintake, it is primarily of the same design. The VIIC Junker air compressors intakes however are of the same execution for all the Uboats see my image. The difference is the hull exhaustvalves which were modified as the Germans had problems with waterintrusion. On your image of the U-570 installation you see the old exhaustvalves, the outer being almost on the same place as the modified version on the U 995 having interlocks with the vent valve on the aft buyoancy tank. The inner exhaustvalve is, as previously mentioned, removed on the museum U-995. See my image below.
Tore

Don Prince · « **Reply #2811 on:** 01 Jul , 2015, 00:51 »

Hello Mr. Tore,

Does this image of the Junkers look OK... The one you provided the text was fuzzy...

Regards,
Don_

tore · « **Reply #2812 on:** 01 Jul , 2015, 08:40 »

Don.
It is a lot better drawing, however it does not shows the air inlet ducts correctly. What is named First stage inlet is the compressor air inlet. This airinlet goes to the diesel combustion air and bouncingchamber as well. On the sketch below I have tried to show the system on your sketch. Air is drawn in via the main inlet air filter. From the filter ducts in the casing the first stage air goes via a branch off to the compressor endcover and is drawn into the first stage compressor cylinder via valves by the inward stroke, filling the first stage cylinder with air. The diesel combustion, scavenging - and bouncing air has a branch off duct in the casing to the underside of the first stage piston where it is drawn in via valves by the outwards stroke of the piston. At the inward stroke this air is forced via another set of valves into the scavenging bouncing chamber and to make it even more complicated, the first 1/3 compression stroke of the first stage compressor piston, deliver air via cylinder portvalves to the combustion- ,scavenging and bouncing chamber as well, leaving only air from the 2/3 of the stroke to the 2nd stage aircompression cylinder.
Tore

Don Prince · « **Reply #2813 on:** 01 Jul , 2015, 19:30 »

Hello Mr. Tore,

I have a problem with the Ju compressor in the way its drawn. I do not see it working, and here is why... If the compressor air inlet is on top, then the two light blue chambers must be swapped from top to bottom. Then when the first stage compressor piston is on a back stroke the valve in the top blue chamber will shut and not force compressed scavenging air out the top compressor air intake. I have redrawn the compressor to see if you agree???

The 2nd issue is ; how do we get pressurized scavenging air into the bouncing chamber? My best guess is that there are open ports in the first stage piston wall very close to the piston top, or crown. When the diesel piston is fully compressed, then the compressor piston would be fully extracted from the compression chamber; the ports would be uncovered in the scavenging chamber and pressurized scavenging air can then enter the bouncing chamber.

I have attached my re-drawing and I will place the input air port on the top of the Ju compressor... What do you think?

Regards,
Don_

Don Prince · « **Reply #2814 on:** 02 Jul , 2015, 00:35 »

Hello Mr. Tore,

Here is what I think it may look like....

Regards,
Don_

tore · « **Reply #2815 on:** 02 Jul , 2015, 01:01 »

Don.
If you look at one of my previous drawings may be it explains the air intakes in an other way.
As you see from the image below there is in fact two inlets after the filter one to the top, first stage inlet chamber, light blue on my image, the air enters the inlet valves at the inwards stroke.
Then there is a second air trunk inlet flange for the combustion, scavenging and bouncing chamber, this air goes into a chamber light blue on my image. From this chamber there are a number of valves the first sets of valves A leads into the space under the first stage piston, at the outward stroke the piston draws the air in via these valves into the chamber behind the first stage piston. At the inward stroke of the piston the air filling the chamber is compressed shutting the valves A and opens the valves B and C into the scavenging, bouncing and combustion air chamber. The air is now filling this chamber until the piston is on the dead end of the inward stroke. Then the piston start its outward stroke creating a underpressure on the backside of the first stage piston shutting the valves B however the air valves C are on the top (compression) side of the piston and the air is still supplied toe the scavenging, bouncing and combustion chamber until the piston passes the valves C. and the valves C are connected to the underpressure of the piston shutting valve C.

I have tried more than 1 hour to put in the A,B and C on my old image but in vain due to my computer problems. Hopefully you are able to understand my idea without these letters. I expect to have the new computer ready by next week end.

Tore

tore · « **Reply #2816 on:** 02 Jul , 2015, 05:54 »

Don.
Finally after 3 hours I manage to get into my photopaint programme, my revised image down below.
Tore

Don Prince · « **Reply #2817 on:** 02 Jul , 2015, 12:18 »

Hello Mr. Tore,

1. The cooling water from the pipe enters a belt chamber around the 1st stage compressor. Is that correct?

2, The small channel just above the water cooling belt line is the air entrance channel for the Ju and it wraps around the 1st stage piston and connects to the lower chamber and the two 1st stage inlets. Is that correct?

That was the part I missed and ended up swapping the upper and lower chambers. I see that was wrong...

Now, everything works for me except the part about getting scavenging air into the bouncing chamber. It looks like there should be ports cut into the 1st stage piston center column near the piston crown. That way when the piston is at a full back stroke, the ports would be uncovered and scavenging air could enter the bouncing chamber???

Regards,
Don_

VIC20 · « **Reply #2818 on:** 02 Jul , 2015, 13:16 »

Hello again. Tore, did the light inside the boat change when running on battery? Like always turning off "unnecessary" light or was the light always kind of reduced?
It is soon time to create the final light map for me and I think compared to old pictures that the light in "Das Boot" is that dark for dramatic purposes. But maybe the light was changed while making the pictures? It sometime looks like they have some extra light from behind and turned of some glaring lamps.

Can you please enlighten (lol) me about the general light conditions aboard the boat?

tore · « **Reply #2819 on:** 02 Jul , 2015, 15:17 »

Don.
1. Yes
2. The yellow chamber on my sketch below is the first stage inlet air chamber in the endcover and the inlet air is the first flange Yellow dotted circle. The air inlet for the scavenging, combustion bouncing chamber, blue, enters at the the second flange dotted blue circle and there is no connection with the first stage compression air.

The air enters the bouncing chamber ( pink) in two ways, at the inwardstroke from the underside of the first stage piston light pink via valves B and for the 2/3 stroke via valves C, then at the outward from 1/3 compression stroke via valves C. Valves B are shut.

Tore

Don Prince · « **Reply #2820 on:** 02 Jul , 2015, 18:33 »

Hello Mr. Tore,

When the 1st stage piston moves backward it uncovers the housing for the 4th stage piston. Therefore the bouncing chamber is exposed to the compressor incoming air. and this air when compressed provides the bouncing effect. It this correct?

Regards,
Don_

Don Prince · « **Reply #2821 on:** 02 Jul , 2015, 22:12 »

Hello Mr. Tore,

Looking at the Ju stage 2 and 3...

1. They don't show a connection between the input valve and the lower chamber for stage 2?
2. There looks to be no connection between the 2nd stage compressed air the 3rd stage?
3. How does stage 2 compressed air get into the 3rd stage cylinder so it can be compressed and output to the 4th stage input?
4. There looks to be a empty valve seat at the bottom of the 2nd stage piston cylinder, why?
5. There looks like there is a port at the bottom of the 3rd stage piston cylinder. That can't be otherwise the 3rd stage piston would be useless?
6. eventually we get 2nd stage compressed air into the 3rd stage chamber, but that chamber also houses the 2nd stage input valve....

Is this compressor a 2 cycle or a 4 cycle compressor? Really confused....

Kind regards,
Don_

tore · « **Reply #2822 on:** 02 Jul , 2015, 23:27 »

Don.
There is no connection between the first stage and the 4 stage cylinder., the only sources for filling the scavenging- combustionchamber are as I mention, the under side of stage 1 piston via valves B and the first stage cylinder port valves C. The 2nd 3rd and fourth stages do not take part in this process.
Tore

tore · « **Reply #2823 on:** 02 Jul , 2015, 23:58 »

Don.
From the compressor stage 1 after the piston passes the scavenging portvalves at 1/3 of the compression stroke the air, which from now on do not take part in the combustion process, goes via stage 1 end cover outlet valves into a pipe to the first stage aircooler under the compressor and then to the other side of the compressor where the pipe enters the inlet for stage 2, from stage 2 outlet it goes via pipe to 2 nd stage aircooler and then enters stage 3 inlet by pipe, not clearly shown, from stage 3 outlet the air goes by pipe to stage 3 aircooler and then by another pipe to the other side of the compressor and stage 4 inlet. From stage 4 outlet the air goes by pipe via stage 4 cooler to the airbanks. Stage 2, 3 and 4 do not take part in the air supply for the diesel section.
The reason for having stage 1 and 4 at one side and 2 and 3 at the other is balancing of the free piston. Each stage has to be cooled before it is passed on to the next stage as there is substantial heat generated by the high pressures the compressor is working. All the 4 tubecoolers are placed underneat the compressor.
The supply pipes to the coolers and between the various stages are not shown on the crossection drawing only the inlet and outlet connections.
Tore

tore · « **Reply #2824 on:** 03 Jul , 2015, 00:20 »

Mark.
First of all, the ligths were not that bright as on to days museums U 995 as we did not have fluorescent lights. In order not to destroy the night vision we used when needed in the control room and tower, red lights. During nights we usually reduced the lights in the living compartments.
The general lights throughout the boat did not vary during the various running condition.
Tore

tore · « **Reply #2825 on:** 03 Jul , 2015, 01:05 »

Don.
The inlet pipe for stage 2 is not shown on the sketch, only the inlet chamber in the endcover.
As stated before it is a two stroke ("cycle") uniflow scavenged four stage opposed free piston dieselcompressor.
Could you indicate on the crossection drawing the items what you are assuming under your questions 4 and 5?
I see I am returning to the bad habit of including the bouncing chamber in the scavenging, combustion air chamber. As I explained in my reply 2456, page 164 January 18th 2015 it is not really a bouncing chamber, as the major bouncing effect is maintained in the compressor cylinders by the pressure maintenance valve in the HP pressureline. I guess the correct name should be scavenging air chamber which means it is the airsupply chamber both for scavenging and filling of combustion air.
Tore

tore · « **Reply #2826 on:** 03 Jul , 2015, 10:46 »

Quote from: Don Prince on 02 Jul , 2015, 18:33

Hello Mr. Tore,

When the 1st stage piston moves backward it uncovers the housing for the 4th stage piston. Therefore the bouncing chamber is exposed to the compressor incoming air. and this air when compressed provides the bouncing effect. It this correct?

Don.
I don`t think so. Down below I have tried to make an image of the piston in the inward dead end, may be this gives you an idea how it works.
Tore

VIC20 · « **Reply #2827 on:** 03 Jul , 2015, 12:21 »

Quote from: tore on 03 Jul , 2015, 00:20

First of all, the ligths were not that bright as on to days museums U 995 …
The general lights throughout the boat did not vary during the various running condition.

Yes I doubt you used such lamps. But would you say the light in "Das Boot" comes close?

tore · « **Reply #2828 on:** 03 Jul , 2015, 12:24 »

Mark.
I dont think the lights in "Das Boot" is too bad.
Tore

Don Prince · « **Reply #2829 on:** 03 Jul , 2015, 20:37 »

Hello Mr. Tore,

I still have a problem understand how you get air into the bouncing chambers… I propose that when the diesel pistons are at full compression that both bouncing chambers have uncovered the internal piston casings and created an opening for air to enter the chambers.

If you examine the 1^st stage piston and the 2^nd stage piston, both have an undercut area on the piston face that rides over the internal piston casing. This undercut provides the space to assure the bouncing chambers are open to air from the external air supply in the case of the 1^st stage bouncing chamber, and the 1^st stage compressed air supply in the case of the 2^nd stage bouncing chamber.

If this opening/condition did not exist, then there would be no way physical to get air into these chambers because they both would be sealed. There are two other possibilities:

1. The seals between the 1^st stage piston and the 2^nd stage housing leaked and allowed air to enter the chamber, but that would most likely negate the bouncing effect as well!

2. There would have to be a valve on the bouncing chamber which would allow air to enter when the 1^st stage and 2^nd stage pistons were drawing air into the 1^st stage and 2^nd stage piston chambers. However, these valves do not exist for either bouncing chamber.

I have drawn what I proposed with measurements from my computer screen, and the same could be done with printed diagrams. This looks to be a working solution to the bouncing chamber air issue. What do you think?

I have attached my measured drawing to go along with my proposal…

Kind regards,
Don_

Don Prince · « **Reply #2830 on:** 03 Jul , 2015, 23:12 »

Hello Mr. Tore,

I believe I have stages 2 and 3 figured out based on a photo of a compressor and the drawing from u-historia.com. what do you think?

I believe those different stages of pressurized air pipes run through a water cooling system...

Regards,
Don_

tore · « **Reply #2831 on:** 04 Jul , 2015, 00:30 »

Don.
The U Historia image gives a better understanding of the 2nd and 3rd stage air connections, and each stage outlet goes through a tube water cooler before it enters the next stage. I agree you can use these sketches. After the air passes the four stages tubecoolers there is a pressure maintainace valve. This valve is shut until the pressure is reaching a preset level which I have forgotten, but it is quite high, before the compressor starts to deliver air to the airbanks. This pressure is, as I previously ( Jan. 18th) and repeated in my post 2826 of yesterday mention, creating the real bouncing effect.
I shall revert to your question on the air supply to the scavenging chamber as soon as I manage to get access to my paint programme.
Tore

tore · « **Reply #2832 on:** 04 Jul , 2015, 03:35 »

Don.
I have tried to illustrate the first stage inlet stroke as follows( sketch below). When the piston is at the outward dead end and start to move inwards, air is drawn into the cylinder at a suction ( under)- pressure via the air inlet chamber and valves D, this air is coloured yellow, piston position 1. As the underpressure is created, the first stage outlet valves E shuts.The inwards side of the piston is now creating an overpressure ( blue) shutting valves A and opening the valves B and C, supplying air to the scavenging chamber, for C via the dotted blue hatched duct.
As the piston moves to position 2 the outward part of the piston side has still an underpressure and shuts now valve C as the piston passed the scavenging air ports, thus shutting the blue dotted hatched connection to the scavenging chamber. The inward side of the piston is having an overpressure, valves B are still open and in connection with the inward side (overpressure) of the piston, supplying air to the scavenging chamber.
When the piston is at the inwards dead end, position 3, I agree to your sketch showing a possibility of a leakage from the first stage "piston pocket" however at the dead inward end the pocket is at its max. expansion and there is hardly any pressure difference between the " pocket " and the outwards side of the piston, thus no significant leakage. Moreover a possible leakage to the 1 st. stage piston underpressure side (yellow) would be contained due to the sealing of the first stage pistonrings, the air can only enter the scavenging chamber when the outward pistonchamber pressure open valves C.
The fixing nut for the 4 stage piston rod is sealing the "pocket" towards the scavenging chamber.

Tore

tore · « **Reply #2833 on:** 05 Jul , 2015, 01:07 »

Don.
I guess it has been cut, see image below, may be you are confused by the exhaust water trap.
Tore

Don Prince · « **Reply #2834 on:** 05 Jul , 2015, 01:09 »

Hello Mr. Tore,

It was an optical illusion with the point of view... I sent another photo showing it was cut...

Regards,
Don_

tore · « **Reply #2835 on:** 05 Jul , 2015, 11:08 »

Do.
The images and photos sometimes distorts the dimensions and distances to an almost unbelievable picture, don`t believe everything you see, particulary from the museum U 995 as they have in addition made several changes from the original.
Tore

Don Prince · « **Reply #2836 on:** 05 Jul , 2015, 20:08 »

Hello Mr. Tore,

I have placed the latest version of Skizzenbuch 11 x 17 - M into dropbox. I updated the graphics and some of the text on the Junkers diesel compressor pages 92 through 97.

Regards,
Don

tore · « **Reply #2837 on:** 06 Jul , 2015, 02:03 »

Don.
Skizzenbuch. A few comments.
Page 93 2nd last section..... through small springloaded valve in the separating plate... and , for approximately 2/3 of the inward stroke, via the valves in the beltchamber encircling the first stage cylinder.
Page 94 Bouncing chambers. I guess you should reduce the importance of the bouncing effect of the first and 2nd stage bouncing chambers a bit. As I previously have said the major bouncing, is created in all the compressor stages by the pressure maintenance valve situated in the HP line after the 4 stage cooler. This valve check that the compressor do not supply air to the banks before an adequate bouncing pressure is built up in the various stages. The pressure is very quickly raised ( as the there is no airdelivery) and is adjustable. The compressor start to supply air when a lowest pressure in the fourth stage is ,as far as I remember, 170 kg/cm2.
Page 97 The image of the Junker compressor air inlet is a bit different. As we have touched upon before we have two inlets, one for the compressor and one for the scavenging air, both having common airinlet filter. I have tried to make an updated image below.
Tore

tore · « **Reply #2838 on:** 06 Jul , 2015, 07:15 »

Skizzenbuch final checking.
On page 87 second section you are still cursing

on the surface.
Page 92. Second section .....connected to the first and forth....Fourth.
Page 339.... are only used if the U boat has been damaged as a result of a aircraft machine gun.....It is used in any event of damage to the ventduct.
Page 443 Diesel engine lubricators. Right. The lubricators... Left.

Tore

Don Prince · « **Reply #2839 on:** 06 Jul , 2015, 22:20 »

Hello Mr. Tore,

1. I hope I have stopped "cursing" on the surface... Page 87
2. I added your text to page 92
3. I cleaned up the bouncing chamber paragraph and came to the conclusion that the bouncing chamber NEVER goes negative. Page 94
4. I updated the drawing on page 97
5. Page 339, I added your text
6. Page 343, some day I will learn which is Left and which is Right!

I uploaded the latest version of Skizzenbuch 11 x 17 - M to dropbox and I will wait for your OK before submitting this final document to Schiffer... After this phase begins the tedious process of re-configuring Skizzenbuch for the publishing printer.

Kind regards,
Don_

tore · « **Reply #2840 on:** 08 Jul , 2015, 00:34 »

Don.
I guess your last corrections are OK. It`s probably impossible to get such a publication flawless as you have put together a number of informations from a so many sources. Anyhow I believe your Skizzenbuch shall give a unique contribution to the understanding of the working and operation of the VIIC`s. The book is more comprehensive than any I got hold of when I started to operate the KNM Kaura ex U- 995.
Tore

Don Prince · « **Reply #2841 on:** 08 Jul , 2015, 17:56 »

Hello Mr. Tore,

Thank you for all your help with "Skizzenbuch: The U-Boat Type VIIC Project".... The best thing for me to hear is that the last corrections are OK, because you are the expert in my opinion and your judgement matters so much to me!

I will stay in touch as always.

Kind regards,
Don_

Don Prince · « **Reply #2842 on:** 20 Jul , 2015, 21:05 »

Hello Mr. Tore,

I just finished a "Prologue" in the first section... These two pages and 6 drawings are intended to give the reader just a little of the basics of when diving and surfacing the U-Boat. I do not cover an "emergency or crash dive sequence. I leave that to be covered within the book.

If you would be kind enough to review what I have done, but keeping in mind this is not intended to cover every detail. In a few weeks, I may have a "Foreword" by Jak P. Mallmann Showell; who has written many books on U-Boats.

I have uploaded the latest version of Skizzenbuch 11 x 17 - M to dropbox...

Regards,
Don_

tore · « **Reply #2843 on:** 21 Jul , 2015, 06:27 »

Don.
I have read your "Prologue" and have following remarks: IV Q was normally not flooded only on warpatrols when you expected a quick dive would be nessecary. Thus Q did not participated in the normal dive.
Middle drawing: when the wind deflector on the bridge and the stern is submerged ( not flooded) simontaneously the boat is on the proper divingangle.
MBT 2 and 4... Vented through a common vent trunk..... and there is a ventvalve lever to blow.... vent.
Otherwise I think the prologue is an exellent idea.
Tore

Don Prince · « **Reply #2844 on:** 22 Jul , 2015, 13:22 »

Hello Mr. Tore,

Thanks for the corrections... I think I got it correct. The 2 pages are in a column format and I run into spacing issues if I add a line. So, I combined the center paragraph so I could get things right. I'm no expert with MS Word columns..

I uploaded the latest version of Skizzenbuch 11 x 17 - M to dropbox..

Regards,
Don_

Don Prince · « **Reply #2845 on:** 22 Jul , 2015, 18:57 »

Hello Mr. Tore and Maciek,

I just got an email from Jak P. Mallmann Showell with the following comments.... Should I change all the German words in the plate indexes that end with "sz" to "ß"?

In many places you use the old fashioned "sz" - this was replaced by a symbol looking like a"B" (ß) and in modern usage since before WWII was written as "ss" instead of "sz"

Regards,
Don_

In many places you use the old fashioned ‘sz’ - this was replaced by a symbol looking like a ‘B” and in modern usage since before WW2 was written as ‘ss’ instead of ’sz’

tore · « **Reply #2846 on:** 23 Jul , 2015, 01:44 »

Don.
I am not a language expert but to me it is natural to use sz when the other letters are gothic.
Tore

Don Prince · « **Reply #2847 on:** 24 Jul , 2015, 13:25 »

Hello Mr. Tore and Maciek,

I sent an email to the U-Boot-Museium in Cuxhaven Germany and receiver the following response...

Dear Don,
since Mr.Monte is not longer on board of our team, but left for family reasons,
I can possibly help you.
In the old times the German language had a "ß" that was a combination of "s" and "z".
Since the handwritten (Sütterlin) letters resembled a "ß", it grew to one separate letter.
But in the meantime resp. since 100 years there is no more written "sz",(it would be incorrect to use it)
but always "ß" when written in small letters, but "SS" when written in capitals,
Messgefäß or MESSGEFÄSS.
We all wish you good luck and success with your certainly very interesting book.

Stay in contact, kind regards
Jutta

Dr. Jutta Baberg
Deutsches U-Boot Museum
Lange Straße 1
D-27478 Cuxhaven-Altenbruch

What do you think?

Regards,
Don_

Don Prince · « **Reply #2848 on:** 25 Jul , 2015, 23:12 »

Hello Mr. Tore,

I had to re-write page 80. I would like to assure that I have gotten your lesson on fuel tank compensation exactly correct, just stated a little different...

The above diagram is indicating the various valves involved in a fuel configuration of the saddle tanks. As a matter of interest, I made a quick calculation of the weight compensation for the difference between the saddle tanks filled with fuel oil (87% the weight of sea water) versus the saddle tanks filled with compensating sea water. With all 4 saddle tanks filled with compensating sea water the weight increase is about 6.5 tons which then had to be taken from the regulating tanks to balance the U-Boat's weight. In the case of not being water compensating tanks, the empty saddle tanks weight loss would be about 43 tons of fuel which would require an equal weight of sea water to be pumped into the regulating tanks to balance the U-Boat's weight. With a total regulating tanks capacity of 24.6 tons, this would be an impossible task. If you do the same exercise for the internal fuel tanks, the total weight increase by compensating sea water filled tanks would be about 9.2 tons and with the saddle tanks increased weight of about 6.5 tons, the total weight gain is about 15.7 tons and still possible to compensate with the regulating tanks' capacity of 24.6 tons. However, without sea water compensating tanks over all the loss of weight would be about 61.5 tons for the empty internal fuel tanks and about 43 tons for the empty saddle tanks; the U-Boat is now about 104.5 tons lighter which must be compensated. This of course was a play with figures with no realistic use, but is just an example of one of the advantages of water compensating.

Regards,
Don_

tore · « **Reply #2849 on:** 26 Jul , 2015, 01:18 »

Don.
I guess you got the idea correctly and again this is a play with figures only. The watercompensatings 2nd advantage is the reduction of the free surface effect which might upset the trim. Reverting to your last Skizzenbuch question soonest, but I am having beginners trouble with my new PC.
Tore

tore · « **Reply #2850 on:** 26 Jul , 2015, 01:59 »

Don.
Your last question on the Skizzenbuch.
Page V. I have read your corrections and have following remarks: On page V 2nd section you are still blowing MBT 3 by the vent.
Page VI. 4 th. section you introduce the keel as the weight compensating for the loss of the submarine stability. I am afraid it is a bit more complicated and difficult to explain by just a few words. For a submarine surfacing the center center of buoyancy is moving in relation to the center of gravity thereby the metacentric hight is reduced causing a less stable submarine as it surfaces. As you don`t have a chapter of this theortical elements I suggest you only state the fact the the submarine stability is reduced without introducing the keel which might be confusing.
If you are interested in the theory of the submarine stability I can recommend this link: maritime.org/doc/fleetsub/chap5.htm a very interesting topic.

Tore

Don Prince · « **Reply #2851 on:** 27 Jul , 2015, 18:00 »

Hello Mr. Tore,

I found a write-up on the Junkers that explains the piston latching in the outer position...

"Starting is achieved by first locking the pistons in the outer dead position, and then admitting compressed air(at about 500 lb per square inch) to the compressor stages. When the first-stage pressure reaches a certain value (between 40 lb and 50 lb per square inch) the latching gear is
tripped and the pistons are flung together."

The key is they admit HP air to the compressor stages and not the Scavenging air box (a miss-read on my part). I apologize...

Regards,
Don_

tore · « **Reply #2852 on:** 28 Jul , 2015, 00:18 »

Don.
It is easy to get confused on the Junker, anyhow you found the correct answer.

Tore

Don Prince · « **Reply #2853 on:** 30 Jul , 2015, 21:35 »

hello Mr. Tore,

I believe the VIIC/41 has a theoretical crush depth of 300 meters with the thicker pressure hull steel plates. I have only found that the control room plate thickness was changed from 18.5 mm to 22 mm. Do you know what changes if any were made to the pressure hull thickness of the other 7 sections?

Also, I checked the photo that you provided of the missing depth gauge from U-995 and I can't make out the numbering, but it looks like the maximum depth indication was 250 meters. If they dived below 250 meters, then were they off the scale, or was a different meter available that indicated down to 300 meters?

Regards,
Don_

tore · « **Reply #2854 on:** 01 Aug , 2015, 01:00 »

Don.
I guess the max operating depth for a VIIC/41 was 250 meter hence both the depthgauges, deep dive- and checking manometers, were scaled to 250 meters. The construction of the pressurehull for increased of max diving depth was mainly due to be able to take evasive depthcharge maneuvres . For the ordinary full circle pressurehull the plating was increased from 18,5 mm to 21mm. The conningtower plating I guess was 32 mm and at the tapered ends of the pressurehull the platethickness was some 3,5 mm less than the full circleplatings. The pressure hull curved endplates were some 35mm , I am not sure how much they were increased on a VIIC/41.
We normally talked about the max. operating depth rather than max. designdepth and if you was at a depth exceeding 250 meters you would consentrate on other problems than the meter being off scale.

Tore

Don Prince · « **Reply #2855 on:** 01 Aug , 2015, 13:10 »

Hello Mr. Tore,

The trumplatte was originally 22 mm thick and I got that info from the drawing Uboottyp VII C - Eisenlängsschnitt (1944) that came with Eberhard Rössler's book "Geschichte des deutschen U-Bootbas, Band 1." I don't believe the tower thickness was changed because the diameter of the tower was not as large as the control room.

However, that 1944 General Plan still shows the control room steel plate thickness as 18.5 mm???

The Germans sure didn't pay attention to the little details in the latter war years... and that is a point of confusion for me...

Regards,
Don_

tore · « **Reply #2856 on:** 02 Aug , 2015, 02:12 »

Don.
A German; I presume naval architect Køhl, has made a longitudenal drawing of a VIIC/41 based on, I again presume, a Norwegian drawing (reference Plan 314) unknown to me, where a lot of infos are noted including the plate thickness. I have put up the figures in a table starting from the aft pressurehull frame 0.

Frame no. Plate thickness mm Distance in mm Schuss Remarks

0 35 0 0 Curved endplate

0-12 16 6000 I

12- 18 appr. 17 3500 II

18 app.-27,5 17,5 5500 III

27,5- 36 appr. 18 7100 IV

36 appr.-50,5 18,5 9100 V Turmplatte mm 22- pressurehull top plate in the tower joint area ( not the towerplating)

50,5-62,5 18 7200 VI

62,5-75,5 17,5 7900 VII

75,5-81 16 3100 VIII assuming bow curved endplate is 35 mm

The 22mm topplate in the tower area is due to the relative large openings in the pressurehull.

Tore

Don Prince · « **Reply #2857 on:** 02 Aug , 2015, 15:40 »

Hello Mr. Tore,

Thank you for the researched data... I will add the additional info to Skizzenbuch.

Regards,
Don_

tore · « **Reply #2858 on:** 03 Aug , 2015, 01:19 »

Don.
A few comments on the diving depths.

Max. diving depth.
The diving depth of a submarine is often confusing as there are many figures mentioned without reference to what the figure represent.

Ther are generally four divingdepth figures.
1. The designed depth.
2. Testdepth.
3. Max operating depth.
4. Crushdepth.

The desinged depth is the theoretical calculated depth based on material, frames , hullopeneings and other physical factors. In this figures the designer includes a safety factor which even can be as high as 2.5
The testdepth is, as it says, the max. depth carried out at the delivery trials and can vary between the different navies. In US navy I guess it is 2/3 of the designed depth, RN 4/7 and the German navy 1/2 of the designed depth. These depths are normally the maximum depths which the submarines in the different navies are allowed to operate in peacetime.
Crush depth is the dramatic figure used by fiction and movie writers and represents the figures where the pressurehull actually collapses. These figures may vary even for the same class of submarines and depend on the quality and workmanship of the various shipyards.
I remember we were discussing the terrible waste of Operation Deadlight were the German submarines were sunk at deep waters, listning and recording the depth when the crushing sound occurred. Unofficially I read somewhere that the collapsdepths of the VIICs were varying between 200 and 280 meters. I wouldn trust those figures.
I don`t believe there are any accurate reliable figures and as I said before we did not spend time pondering upon same.
Tore

Don Prince · « **Reply #2859 on:** 03 Aug , 2015, 21:21 »

Hello Mr. Tore,

I'm in the process of updating the info on the Papenberg depth gauge and I have a few questions.

Q1. The height of the attack periscope from the keel fully extended is 14.663 meters. When the captain orders the U-Boat to periscope depth; that is 18 meters and then the periscope is fully extended and under cut (below the surface). Then the U-Boat rises and when the periscope is free (above the surface), then that depth is noted. (U-Boat Diving Manual)...

Q2. Is the papenberg water column source located at the bottom of the keel? I'm not sure?

Q3. Setting up the Papenberg - when the U-Boat ascend to 20 meters using the large depth gauge (0 - 25 m), and then they open the water valve to the Papenberg to establish the water level; then adjust the water column to read 20 meters? I would think that the u-boat's internal pressure +/- would make all the depth gauges inaccurate?

Q4. The scale on the left side displays the residual buoyancy/displacement in metric tons. On an initial trim test I believe the U-Boat has all the MBTs flooded, the Q-tanks are empty. The tower would most likely be above the water surface. If the Papenberg inlet valve was opened, then the water level in the tube would rise to some point on the left scale. If they read the level it should tell them how much water needs to be pumped into the regulating tanks to get to the tower deck awash? or would it be to the tower hatch covered? There is a red marked "0" on the left scale.

I have attached a photo of the Papenberg scales.

Regards,
Don_

VIC20 · « **Reply #2860 on:** 04 Aug , 2015, 16:34 »

Hello Tore,

Command Room of U 570 has a 3rd sight glass, do you know what its function was?

And what are the discs above the depth rudder control good for?

Don Prince · « **Reply #2861 on:** 04 Aug , 2015, 19:47 »

Hello VIC20,

The caption below the photo reads as follows...

"Control Room starboard side forward showing diving plane controllers, hand wheels for manual operation of diving planes, diving plane angle indicators, Bourdon tube type shallow diving depth gauge, closed end tube type "attack" depth gauge, closed loop inclinometers (one with coarse graduations and one with fine graduations), and propeller r.p.m. indicators - Case of deep diving depth gauge is shown at right of photograph - A mechanical diving plane indicator can be seen back of each diving plane hand wheel."

It looks like it's a 2nd inclinometer, one course and one fine... Perhaps, the disks in back look to be the mechanical hydroplane angle indicators???

Regards,
Don_

tore · « **Reply #2862 on:** 04 Aug , 2015, 23:07 »

Mark.
This is indeed a mechanical hydroplane indicator operated by a wire inside a flexible tube, a so called teleflex system.
Tore

tore · « **Reply #2863 on:** 05 Aug , 2015, 02:46 »

Don.
Q1. I don`t think there is any standard attack periscope depth. The attack periscope depth is ordered by the CO and may vary depending on light conditions, sea and other prevailing parameters at the time of the attack. I believe the main thing is to hold the boat stable in relation to the surface letting the CO take the small adjustment himshelf.
Q2 and 3. I don`t see the need for going all the way to the keel for the seaconnection for the Papenberg. As long as you have a submerged connection all the time you shall have the waterpressure variables the same whether it is coming from the watersurface down to 14 meters or from 14 meters down to 28. Remember it is the compression of the air in the bufferchamber which is controlling the watercolumn. The adjustment of the Papenberger can actually be done in several ways, all based on adjusting the airpressure in the bufferchamber. F.inst. by having a cock on the top of the chamber letting air out thereby raising the watercolumn, or as the case of U 995 having a draincock at the bottom of the gauge assembly draining the water thereby reducing the aircompression (raising the water column).As far as I can see the Papenberger on board present days U-995 has a scale which put a 0 depth at the position where the tower wind deflector is breaking the surface, which means 9400 mm from the bottom of the keel. You can of course use any reference point.
Q 4. On the left scale on the U-995 is a sketch showing the attack periscope with depthmarkings, I am not sure the scale shows the residual displacement tonnes. I cannot recall we used the Papenberger for accurate adjustment of the regulating tanks.
Tore

Don Prince · « **Reply #2864 on:** 05 Aug , 2015, 12:14 »

Hello Mr. Tore,

Thank you for the update... The only thing that seems to be a mystery to me is what exactly is the function of the index pointer that slides up and down on the rod on the right side of the Papenberg meter scale?

Regards,
Don_

tore · « **Reply #2865 on:** 06 Aug , 2015, 07:55 »

Mark the 3rd sightglass is the inclinator eg. the instrument for measuring forward/ aft trim like diving angle and it work as per image below.
Tore

VIC20 · « **Reply #2866 on:** 07 Aug , 2015, 14:55 »

Thanks Tore and Don, so the 3rd one of the two inclinators is identical to the one in U 995 (which comes with only one inclinator) right? The other Type VII you served on, did she had one or two inclinator gauges?

How did the mechanical hydroplane indicator displayed the angle? I don't see a gauge needle on any of the pictures. Did the mechanical hydroplane indicators always work or only when the manual wheels were used (instead of the electric motors)?

Which raises another question, the manual wheels could be decoupled right? Or did they always rotate simultaneously when a button was pressed on the electrical "BBC" controller?

Quote from: Don Prince on 05 Aug , 2015, 12:14

The only thing that seems to be a mystery to me is what exactly is the function of the index pointer that slides up and down on the rod on the right side of the Papenberg meter scale?

I can only guess but I believe it is a marker which can be set to quickly mark a desired depth. I think this would be useful if the attack periscope is in use. The usable height of the observation periscope was very limited (operators must bend themselves if they want to lower it). So when the observation periscope was in use then the desired depth (to keep the head just low above the surface) was basically always the same. But the attack periscope was usable at almost any extension (at least this is what I understand from the description in Harry Schlemmer's book "Vom Turmsehrohr zum Optronikmast"), hence the "periscope depth" of the boat and the extension of the attack periscope could vary which makes a quick marker useful. But this is just my first thought and I bet I am totally wrong

Something different that I absolutely don't understand:
The head of older versions of the C/2 attack periscope (till 1942) were pressure proof up to 15 bar only (equal to approx. 150m) later ones up to 25 bar (250m). I think even with a fully retracted periscope the head was still visible and had no additional protection (or is that wrong?). This would mean the older boats could dive to a maximum depth of 150 meters only because above that they would risk an ingress of water through the periscope.

Don Prince · « **Reply #2867 on:** 07 Aug , 2015, 20:24 »

Hi Mark,

I will eventually get everyone's name right... I found a photo that shows a lid placed over the tube casing of the aerial periscope. I can't explain why, because if the lid is left on and they come up from a deep dive; do they just pop the lid off when they raise the periscope? Perhaps Mr. Tore has an explanation?

Perhaps the lid has a chain attached and they just pop it off the periscope tube casing when the aerial periscope is raised, and put it back in place after surfacing???

The attack periscope is located up in the tower and the captain is seated right in front of the eyepiece (no bending) the upper section of the attack periscope is what is raised and lowered..

Regards,
Don_

tore · « **Reply #2868 on:** 08 Aug , 2015, 08:45 »

Mark and Don.
On the U-995 and U-926 we used only one Papenberger as far as I can remember. It looks indeed on your image that it is a 2nd. Papenberger with somewhat larger glass for higher accuracy.
The manual operation of the hydroplanes was normally disconnected by a dogclutch situated locally next to the hydroplaneshaft, thus the wheels did not turn. You could connect the mechanical drive pneumatically from the hydroplane operators place, see my image, to reset same you had to do it locally though.
On my image below I have indicated the mechanical pointer of the teleflex system frrom U-570.

I am not sure where you got the pressureproof figures for the periscopes. 150 meters was the 1939-1942 testing pressure for the pressurehull plating. I should certainly think the periscopes could take more than that. Another thing is the operation of the periscopes. If you are going deep you lower the periscope to the endplates relieving the strains on the wires. However sometimes you let the boat hang on the periscopes when you need to go absolutely silent. You shut down the pumps and adjust the bouyancy by lowering and raising the scopes, ( changing displacement) using the stored energy in the hydraulic accumulators. It could be a limiting max.factor on these operations which is rather due to the wires than the scopes.
To my knowledge we never used any pressureproof caps on the periscopes.
Tore

VIC20 · « **Reply #2869 on:** 08 Aug , 2015, 19:27 »

Quote from: tore on 08 Aug , 2015, 08:45

On my image below I have indicated the mechanical pointer of the teleflex system frrom U-570.

Thanks, I first thought this is a shadow.

Quote from: tore on 08 Aug , 2015, 08:45

I am not sure where you got the pressureproof figures for the periscopes.

From a book about German Zeiss Periscopes, written by Harry Schlemmer a physicist of the Zeiss AG.
http://www.koehler-mittler-shop.de/Programm-Koehler-15/Vom-Turmsehrohr-zum-Optronikmast-Schlemmer-88.html

Quote from: tore on 08 Aug , 2015, 08:45

However sometimes you let the boat hang on the periscopes when you need to go absolutely silent. You shut down the pumps and adjust the bouyancy by lowering and raising the scopes, ( changing displacement) using the stored energy in the hydraulic accumulators.

Wow, I need to add this to the simulation of the more complex 2nd title

Don Prince · « **Reply #2870 on:** 15 Aug , 2015, 22:58 »

Hello Mr. Tore,
Hello Mr. Tore,

While reviewing page 340 and looking at the attached drawing of the threaded carriers to open and shut the Kingston Flap valves in MBT 3, I have come across an issue with the aft drive mechanism. the attached drawing does not provide enough detail about the threaded carriers that cause the Kingston Flap valves to swing open and shut while the threaded carrier moves up and down on the threaded drive shaft. See my attached drawing.

Do you have better drawings of these threaded carriers? Especially the aft carrier that only drives 1 Kingston Flap Valve... My attached drawing seems to answer the issue where the threaded carriers and the attached drive rods have the ability to swing and follow the Kingston flap valve attachment point. That point, besides moving down also moves to towards the keel. See where I have marked the poor drawing with yellow circles of the drive rods swinging point. what I need is better details...

Regards,
Don_

PS - The drawing seems to indicate the threaded mechanism may be attached to the internal longitudinal bulkhead in MBT 3 at an angle - where the bottom of the screw drive shaft is further away from the bulkhead and that does make sense???

Does Simon have any drawings of MBT 3 internals? I know he is great on details and always gets the mechanical stuff correct?

tore · « **Reply #2871 on:** 16 Aug , 2015, 01:06 »

Don.
Unfortunately I dont`have access to my paintprogramme but I believe the best image would be that of plan 28. The fixing points to the centerbulkhead would be the two endbearings. In beween these bearings is the threaded shaft located. The driveshaft up to the controlroom having two universial joints allows the shaft to operate under an angle rotating the threaded shaft between the two fixed bearings, The travelling nut ,in this case the yoke, moves up and down as the threaded shaft rotates and thus operates the kingstons. I suggest you use plate 28 as an illustration which is more correct than your present image. I have tried to indicate what I mean on the image below.
Tore

Don Prince · « **Reply #2872 on:** 16 Aug , 2015, 20:45 »

Hello Mr. Tore,

Thanks - I updated my drawing and will post it...

I have a few questions about MBT 3. You stated MBT 3 was nice and clean with a fresh coat of zinc chromate paint and there was a man-hole in the internal longitudinal bulkhead... How did you get inside of MBT 3? Through an open Kingston valve? If that were the case, then why the man-hole?

Regards,
Don_

tore · « **Reply #2873 on:** 17 Aug , 2015, 08:17 »

Don.
As far as I vaguely remember we were able to squeeze in via the Kingston openings, may be the Kingstons were dismantled. This was some 65 years back and I was at that time a very skinny guy.
I see for some reason you want to have the threaded shaft and travelling nut on the aft Kingstons placed in an angle, I don`t see the reason for that, I believe the threaded shaft and bearings are vertically fitted and the driveshafts having universal joints have an angle.
Tore

Don Prince · « **Reply #2874 on:** 17 Aug , 2015, 23:18 »

Hello Mr. Tore,

OK, what you remember is good enough for me... I will work on the drawing. (Done)...

Regards,
Don_

Don Prince · « **Reply #2875 on:** 18 Aug , 2015, 00:35 »

Hello Mr. Tore,

Sometimes I think too much and forget some of the many lessons you have taught me...

any way...

MBT 3 has 6 Kingston valves normally open so the U-Boat can dive... Right? Why on earth would they ever want to close them? If on a war patrol with closed Kingston's they can't dive, so they may as well run up a white flag because they can't out gun a destroyer and they would be ducks in a pond for aircraft?

I certainly am missing something... I did think of one thing... make it a museum U-Boat!

Regards,
Don_

SnakeDoc · « **Reply #2876 on:** 18 Aug , 2015, 02:38 »

Hi Don,

Quote from: Don Prince on 18 Aug , 2015, 00:35

MBT 3 has 6 Kingston valves normally open so the U-Boat can dive... Right? Why on earth would they ever want to close them? If on a war patrol with closed Kingston's they can't dive, so they may as well run up a white flag because they can't out gun a destroyer and they would be ducks in a pond for aircraft?

The Kingstones of the MBT 3 were shut while staying in the harbour - to prevent the boat to submerge accidentally, especially, when the hatches other than conning tower hatch were opened. During the war patrol, the regulations prescribed the Kingstones to be opened.

--
Regards
Maciek

tore · « **Reply #2877 on:** 18 Aug , 2015, 04:04 »

Don.
Maciek has already answered your question. I may add in general Kingstons are bottom valves in any ships. For submarines they are vital as Maciek explains, an additional advantage of MBT 3 Kinstons would be if you have a maintenance job on the the vents you are able to do this afloat without having to return to a drydock harbour. On the VIICs you have an additional possibility by shutting the emergency shut off vents in the vent ducts. But think about how easy somebody could pull the venting handle by just removing the lockingpin.
Tore

Don Prince · « **Reply #2878 on:** 18 Aug , 2015, 22:01 »

Hello Mr. Tore,

U-Boats which were declared unfit for sea. U-926 had an over stressed MBT 3 creating structural damage to the pressure hull. This damage was caused by a mistake when blowing the tank by her crew during the end of WWII.

How could they over stress MBT 3? Did they do a HP blow with the Kingston valves and the vent valves shut? The only place where the Kingston valves for MBT 3 are shut is in the harbor area.

That sure looks like the CO or Engineering Officer didn't like the idea of surrender...

Regards,
Don_

tore · « **Reply #2879 on:** 18 Aug , 2015, 23:43 »

Don.
I never saw the report from the German navy as to the actual cause of the structural damage other than it appeared during a deep dive test in the southern area of Norway early 1945. She was then moved to Bergen where she surrender May 9 th. 1945.
Your remark of hoisting a white flag for surrender is interesting. When the German submarines surrender in Norway May 9th. 1945 ,there were 97 of them, they were ordered to raise a black flag preferably on the starboard side by the allies when transferred to other locations. I some times have wandered why, because the white flag is international approved by the Hague-Convention of 1899 and 1907 as the official flag of surrender. Could it be the RN would not have a surrender flag which could be taken for the RN`s White Ensign?
Tore

SnakeDoc · « **Reply #2880 on:** 19 Aug , 2015, 01:22 »

Hi Don,

Quote from: Don Prince on 18 Aug , 2015, 22:01

How could they over stress MBT 3? Did they do a HP blow with the Kingston valves and the vent valves shut? The only place where the Kingston valves for MBT 3 are shut is in the harbor area.

The one way to damage the MBT 3 is blowing it with HP air with the Kingstones shut. As you said, the flood valves should be shut only in harbour area. I can not speculate, if someone could intentionally shut the valves and then blow the tank.

The other way is to blow MBT 3 "too fast" - the Kingstones are opened, but the pressure inside the tank increases because the water can not evacuate through the flood valves fast enough. Theoretically you could calculate the maximum flow knowing the cross-section area of the Kingstones (I believe Mark is good in these stuff). When you exceed this maximum flow, the pressure inside tank can not be released and can damage the tank.

The similar issue is when you blow negative buoyancy tanks - the operators had to carefully monitor the pressure of the admitted air to avoid the damage of the tanks.

--
Regards
Maciek

VIC20 · « **Reply #2881 on:** 19 Aug , 2015, 01:43 »

She became an experimental boat in Pillau on 11.11.1944. On 19.12.1945 she collided with U 1131. After repairs in Kiel she became a front boat and was transferred to Stavanger on 1.4.1945, she got attacked by an aircraft on 4.4.1945, due to bad weather (!!!!) she had to stop two times in Kristiansand (4.4. and 5.4.) and once in Egersund (7.4.). She arrived in Stavanger on 8.4.1945 and was sent on 14.4 to Bergen for repairs. On 15.4. she arrived In Bergen and repairs of MBT3 started. At the end of the war she was not transferred to England because she was unseaworthy.

from:
http://www.ubootarchiv.de/ubootwiki/index.php/U_926
And a search for U 926 on http://historisches-marinearchiv.de/projekte/duikboot/ergebnis.php

Seems it was the result of the attack of the aircraft, it is obvious that they could barely keep her afloat after the attack.

tore · « **Reply #2882 on:** 19 Aug , 2015, 02:11 »

Mark.
This is interesting news and a bit more according to the first story I heard, what is a puzzle though is the mentioning of the structural damage to the Tauchbunkers which would mean either MBT 2 or 4, whereas I saw in 1954 the damage in MBT 3 starboard side repaired as well as some dents. I was then told it was due to a depthcharge bomb attack from an airplane, this was later corrected by some documentation from air commodore Derek Wallers to be overstressing by wrongly blowing by the crew. Unfortunately I don`t have access to these documents right now.
Tore

tore · « **Reply #2883 on:** 21 Aug , 2015, 00:37 »

In a search for the black flag instructions I came across the surrenderinstruction to the German Uboat and discovered to my astonishment that the Uboats were instructed to fly a large black or blue flag, an explanation why is not given.
Tore

Don Prince · « **Reply #2884 on:** 21 Aug , 2015, 18:34 »

Hello Mr. Tore and Maciek,

Jak P. Mallmann Showell did a quick survey of my book about 3 weeks ago and suggested that I have someone to proof read the book and fix the many issues; German "SZ" in place of "SS," many German words were spelled wrong and missing the Umlaut, etc... I have gone over the German text in the Sheet Indexes and corrected what I believe was missed or incorrect in the original text from uboatarchive.net. In addition, I have corrected some of my many poorly worded sentences.

I have uploaded my latest version of Skizzenbuch 11 x 17 - M to dropbox which will be the printed version for my Leather Post Binder. This will be printed sometime during the first week of September, and this is what I will take to Schiffer Publishing the next week. There are several blank pages in the first section for Publisher information and the foreword.

Mr. Tore would you please review the contributors section about you and If you approve, or if you would like to add any personal data, then please let me know, and would you please review page 340 with the changed information on MBT 3.

Maciek, If you would like to add a photo and any personal information about yourself in the contributors section, then please do so. Your emails and postings on this web site have made a significant contribution to my U-Boat education and Skizzenbuch.

All, Please feel free to make any suggestions or corrections because I would like to get this book published in a version that is near excellent in documentation, and presentation.

Kind Regards,
Don_

VIC20 · « **Reply #2885 on:** 22 Aug , 2015, 03:52 »

How much german is in your book? I could take a look on it.

Don Prince · « **Reply #2886 on:** 22 Aug , 2015, 11:21 »

Hi Mark,

There are about 34 pages of German Text, but the type is in a very large MS Word 18 point format for the indexes and some pages range from 3 lines to about 20 lines. Not that huge...

Mark, If you send me an email, then I can go to dropbox and send you a link to "Skizzenbuch 11 x 17 - M" and I only ask that you not distribute the PDF because the Book will be published by Schiffer Publishing Ltd. here in the USA with international options.

My email address is donprince5207@comcast.net

If you have time to scan through the book, them please advise me of your opinion and if you spot any issues with the illustrations or text, then please advise me so. The book is highly illustrated and the text is fairly brief by design.

Kind regards,
Don_

VIC20 · « **Reply #2887 on:** 22 Aug , 2015, 13:19 »

email sent

Don Prince · « **Reply #2888 on:** 22 Aug , 2015, 18:53 »

Hi Mark,

My wife Maureen and I just got back from dinner... I went to dropbox and sent a link. Please let me know I it does not work?

Regards,
Don_

VIC20 · « **Reply #2889 on:** 22 Aug , 2015, 18:59 »

I've got it.

Don Prince · « **Reply #2890 on:** 22 Aug , 2015, 20:49 »

Hello Mr. Tore,

While I was re-doing your info, I googled "Gosport" and found a photo of an A Class Alliance S67 which looks stunningly like a U-Boat with the sail updated...

Regards,
Don_

tore · « **Reply #2891 on:** 23 Aug , 2015, 00:45 »

Don.
The "A" class was very different from the VIICs, much larger, 1385 tonnes surfaced 1620 submerged, 85,5 meter O.A. 61 crew, 6 bow torpedotubes and 4 aft, and designed after the Pearl Harbour experience for the Pacific. The dome on the bow is the Sonar.
The CO had his own cabin in a small separate pressurehull next to the tower.HMS Alliance is a very well known submarine to me as she was stationed all the time in Gosport at HMS Dolphin when I was there. The class as such never took part in WW2 as only two submarines were commissioned before the capitulation. The sail came after my time but you clearly see the folded hydroplane very much different above the waterline.
The resemblance of a VIIC might be due to the "A" class bow flare as the Atlantic bow on the later VIICs.
Tore

tore · « **Reply #2892 on:** 23 Aug , 2015, 07:35 »

Don.
Skizzebuch MBT 3 Kingstons.
I have read your page 354 on the MBT3 Kingstons. May be you make it a bit complicated and to me it gives an impression the threaded rod with the travelling nut (yoke) is fitted on a atwarthship bulkhead. I guess it is on the alongship centre bulkhead. The greaselines do not have to be flexible as they are fitted to the fixed points bearings on the centre alongship bulkhead. The Kingstons are opened into a recess in the keel, well protected. I have tried to show my idea on the image below.
Tore

Don Prince · « **Reply #2893 on:** 23 Aug , 2015, 18:44 »

Hello Mr. Tore,

I found a photo of the keel being constructed, so I can make a correction based on the Keel structure. Could you post the photo that you used with your drawing? It looks like the screw jack may be raised a little by the keel structure, so I will redraw and the make a correction and post for your approval.

Regards,
Don_

Don Prince · « **Reply #2894 on:** 23 Aug , 2015, 21:30 »

Hello Mr. Tore,

Does this drawing look OK? I added a guide bar in back of the carrier and the reasons are:
1. We don't have the real engineering drawings.
2. You don't want the carrier applying torque pressure on the Kingston drive rods.
3. It only seems logical.

Regards,
Don_

tore · « **Reply #2895 on:** 24 Aug , 2015, 02:41 »

Don.
I guess you got the idea. I am not sure of your guidebar though, it could be the threaded bar has a sleeve with slots as shown on the image below. This system is used in the VIICs quite frequently on vents and flapvalves. The distance of the threaded bar from the centre bulkhead can be adjusted by putting shims between the bearing pedestal and the centre bulkhead.
I have tried to make a sketch showing the protecting pocket in the keel, my photo of the system does not show the Kingstons as it is an image of the museum U-995 where they have welded plates covering the kingston gate. I guess they don`t want have people trying to enter the tank.
Tore

Don Prince · « **Reply #2896 on:** 24 Aug , 2015, 14:07 »

Hello Mr. Tore,

I agree; there may not be a guide rod, they could have had a guide track welded to the longitudinal bulkhead, or a multitude of ways to keep the carriers from turning; especially since the threaded shaft is exposed to sea water and the threads could have rusted. Making the carriier drive shaft difficult to turn.

Regards,
Don_

Don Prince · « **Reply #2897 on:** 24 Aug , 2015, 20:14 »

Hello Mr. Tore, Maciek, Mark, and Simon,

I have uploaded the latest version of "Skizzenbuch 11 x 17 - M" to dropbox. I still have to update the Contributors section with additional info when available with photos. I have done another English Grammar and Spelling check up to page 122. After I get the German text corrections from Mark, I will be updating the German text as well.

I sent Simon a PM through this web site, and I'm hoping it works. I would like to assure that Simon gets the proper credit for his excellent drawings.

Regards,
Don_

Don Prince · « **Reply #2898 on:** 25 Aug , 2015, 22:40 »

Hello Mr. Tore, Maciek, Simon, and Mark,

so far I have reviewed up to page 211 in Skizzenbuch and added the info about Simon.

Simon, I sent you a link to Skizzenbuch 11 x 17 - M, and please let me know if you have any issues with dropbox. Also, let me know if I need to make any changes to your Contributors entry...

Kind regards,
Don_

tore · « **Reply #2899 on:** 25 Aug , 2015, 23:22 »

Don.
I am right now in a remote area of the country having limited access to the net and not being able to download your latest version of your Skizzenbook, hope to be able to get back by coming weekend.
Tore

NZSnowman · « **Reply #2900 on:** 27 Aug , 2015, 18:37 »

Hi Tore

I found a little amount of free time yesterday so I took a look at my engine room drawing of the Cooling-water system & anti-corrosion oil-circulating system.

Would the valve ‘e’ be access but a small deck plate hatch or access by removing the whole deck plate?

Fig. 1. Red circle is the location of valve ‘e’ below deck.

Fig. 2. Red circle is the location of valve ‘e’ above deck.

Don Prince · « **Reply #2901 on:** 27 Aug , 2015, 18:48 »

Hello Mr. Tore, Maciek, Simon, and Mark,

I have Grammar and Spell checked Skizzenbuck up to page 275 and posted the latest version "Skizzenbuch 11 x 17 - M" into dropbox.

Maciek, I added the web site as per your request, Please let me know if it is OK?

Simon, I replaced the images I had with the new Hi-Res images you sent me = Thank you!

If anybody sees and documentation errors or errors of any kind, then please let me know so that I may correct them...

Regards,
Don_

tore · « **Reply #2902 on:** 27 Aug , 2015, 23:50 »

Simon.
Good to have you back. The valve (e) is the coolingwater connection valve to the aft torpedo room. The elements there like E motors, compressors, thrustbearings and sterntubes have their own systems including pumps and back ups, thus this e valve is very seldom used. As I don't`t think this valve needs to be frequently operated, I guess it would suffice to have access by a simple floorhatch or plate, possibly only floorplate.
I guess somehow your system drawing placed the (e) at the discharge pipe from stb main engine cooling waterpump and not to the connection pipe to the aft torpedoroom.The latter connection is a central pipe going directly aft. Kindly note the coolingwater digram plate 13 has a mistake, the suction connection to the stb enginedriven cooling waterpump as well as the electric driven reserve coolingwater pump are hooked up to the main coolingwater crossover line, on plate 13 it is marked as no connection.
Tore

tore · « **Reply #2903 on:** 28 Aug , 2015, 23:36 »

Don
Your latest Skizzenbuch. In your prologue, middle dawing diving sequence page VIII, you still have a wrong wording on the venting of MBT3.
.........there is a ventvalve lever on both sides of the control room to blow the ballast for MBT3...... As you know and mentioned before you don`t blow the ballast by these venting levers.

Tore

Don Prince · « **Reply #2904 on:** 31 Aug , 2015, 14:14 »

Hello Mr. Tore, Maciek, Simon, and Mark,

Mr. Tore - I corrected the dumb mistake in the prologue, thanks for keeping me correct!

Maciek - I added the info you provides about the Fwd Torpedo Room Gyro Angle Receiver and thanks for the info.

Mark - Thanks for the info on the German text, I updated Skizzenbuch with what you provided and I went through the rest of the indexes. I corrected the miss spelled that I could find (there were several) and checked them with a web German translator to verify my changes. It would be probably best to use the latest version of Skizzenbuch in dropbox.

I updated Skizzenbuch 11 x 17 - M with the latest changes, and I have about 50 pages to verify the text for Grammar and spelling...

Kind regards,
Don_

Don Prince · « **Reply #2905 on:** 02 Sep , 2015, 01:22 »

Hello Mr. Tore, Maciek, Simon, and Mark,

I have finished my grammar and text review and placed the latest version of "Skizzenbuch 11 x 17 - M" in dropbox.

If no issues are raised, then I will most likely print this version to take with me to Schiffer Publishing next week. Wish me luck...

Kind Regards,
Don_

Don Prince · « **Reply #2906 on:** 06 Sep , 2015, 21:40 »

Hello Mr. Tore, Maciek, Simon, and Mark,

I have uploaded the latest version of "Skizzenbuch 11 x 17 - M" into dropbox. This version has all the German text corrections.

Mark has done a fantastic job in helping me with the spelling and symbols in the German text in the indexes. For over a week, Mark has worked with me on a time intensive job. I have worked on an average about 16 hours per day, and one all-night-er, and I know Mark has done the same. I can't thank Mark enough for his tireless effort.

Regards,
Don_

SnakeDoc · « **Reply #2907 on:** 25 Sep , 2015, 08:36 »

Hi Tore,

some time ago we had a short discussion on the naval uniforms. I have a request to you: could you please identify the uniform visible on the attached photo?

--
Thanks, regards
Maciek

tore · « **Reply #2908 on:** 25 Sep , 2015, 10:54 »

Maciek.
I am not at all very conversant with the different naval uniforms so this is just guesswork. I guess it is a German oberleutenant zur zee looking at the cap. after WW2. If it is an east German naval uniform it must be later than 1990 as the shoulderboards are removed. As you cannot see how many buttons the are on the jacket it is hard to tell whether there is a Bundesmarine or a late east German uniform, the early east German jacket had 10 buttons whereas the Bundesmarine I guess had 8 as the later east German naval uniform. I am sure there are other people having a better founded opinion.
Tore

SnakeDoc · « **Reply #2909 on:** 28 Sep , 2015, 02:16 »

Hi Tore,

thank you for your answer.

Best regards
Maciek

Don Prince · « **Reply #2910 on:** 29 Sep , 2015, 23:26 »

Hello Mr. Tore, Maciek, Simon, and Mark,

I thought I should post an update... My wife Maureen and I drove the 750 miles to Schiffer Publishing in Atglen PA. It rained all the way there, but we stopped over half way there in Roanoke VA. We met with Pete Schiffer and my managing editor Bob Bionde and their staff; they were all very friendly and are great group of people to work with in publishing Skizzenbuch.

I attended several seminars covering all aspects of creating, publishing, and advertising a book. The facility is really a huge warehouse which stores many thousands of books. Previously I printed Skizzenbuck at the Office Depot and placed it into my metal leather covered post binder. Office Depot printed Skizzenbuck on 11` x 17, 9.5 mil, 80 pound card stock. The book is about 2 1/2 inches thich and probably weighs 20 pounds... Heavy Reading!!!

Bob liked the way Skizzenbuch was set-up graphically and asked that that I send the Post Binder for the graphics entry staff as a guide when entering my coding into the system.

MY CODING... I had to read a Publishing Building Guide and create a text file and a folder for all the graphic files. The coding involved defining all the various font sizes and then listing a command any time the font changes, and a command to insert a graphic file, location, and size. Coding is much more difficult than asking Mr. Tore, or Maciek how things work on a U-Boat. I'm at page 100 in my coding so far...

I believe Skizzenbuch will be very close to the 11 x 17 format and it will be in a book slip cover. I still need to talk with Bob anout the 7 large sheets that I have in a wallet folder in the back section of my post binder. Well, that's it so far....

Regards,
Don_

tore · « **Reply #2911 on:** 05 Oct , 2015, 00:36 »

Don.
Thanks for the update. I am impressed by the effort you are putting into your project. Wishing you all the luck and looking forward to receiving your further update.
Tore

Don Prince · « **Reply #2912 on:** 19 Oct , 2015, 14:20 »

Hello Mr. Tore, Maciek, Simon, and Mark,

I have uploaded the latest version fo Skizzenbuch into dropbox. A few photos were changed and re-arranged in the U-Boat Pressure Hull Construction segment throughout the book; nothing major.

Mr. Tore, are you still at your vacation home in the country, or back in the city?

Regards,
Don_

tore · « **Reply #2913 on:** 19 Oct , 2015, 14:25 »

Don.
I am back to the urban life and shall study the new latest Skizzenbuch tomorrow.
Tore

Don Prince · « **Reply #2914 on:** 19 Oct , 2015, 19:11 »

Hello Mr. Tore,

Welcome back... Just to be certain; page 39 - the green vent lines between Regulating and RFO tank 1 and Regulating tank 2 each have a muffler in the plate 7 drawing. However, we stare there is only 1 muffler... Is that statement correct? I just want to make sure.

Could it have been different for U-570 Vs U-995 or U926?

Regards,
Don_

tore · « **Reply #2915 on:** 20 Oct , 2015, 00:37 »

Don.
This is a typical example how the systemsketch deviates from the real thing. The sketch shows the principle, whereas the the real execution is the practical spacesaving reality. Indeed it is only one muffler for the combined port and stb systems. As the muffler only relieve the air it has ample capacity. I guess the system is applied on all VIICs.
Tore

Don Prince · « **Reply #2916 on:** 20 Oct , 2015, 23:04 »

Hello Mr. Tore,

I believe I had text issues on page 40, so I cleaned it up to make it more accurate (I hope)! I uploaded the corrected version of Skizzenbuch to drop box for your approval. It amazing to still find issues with the text after reading it over so many times. I guess my mind just fills in the correction as I read the book and I miss correcting the text errors!

Regards,
Don_

Don Prince · « **Reply #2917 on:** 21 Oct , 2015, 00:13 »

Hello Mr. Tore,

The locking pins for MBT 2, MBT 3, and MBT 4 vent levers in the control room were only installed when at Port... correct? I can't imagine they would want the pins installed when on a war patrol... They could be in an emergency crash dive situation and the locking pins removal would be an unnecessary delay.

Do you remember if the locking pins were ever used on Kaura (U-995) or Kya (U-926)?

Regards,
Don_

tore · « **Reply #2918 on:** 21 Oct , 2015, 00:28 »

Don.
I checked your latest correction on the common mufflers OK. I have a feeling that proofreading of your Skizzenbuch is a never ending task. On page 260 you still let the naughty female raise and lower your periscope

. Wench on the sketch two places. On page 370 you have an image of a ship with broken back, you name the ship a tanker, it looks more like a drycargo vessel look at the cargobooms and hatches.
Tore

tore · « **Reply #2919 on:** 21 Oct , 2015, 01:18 »

Don.
When a submarine leaves the harbour the CO issue an order as to the state of seaworthiness of the vessel depending upon the mission, weather etc. This order usually includes if Kingstons should be open, Q filled or vent locking pins and stanchions removed etc. the order is normally put down in the CO.s orderbook and NO1 is responsible for the execution (R Nor.N). In peace time usually the locking pins are in and only removed when the order "prepare for diving" is given. On war patrol you would always be prepared for diving hence the lockingpins are removed. In peace time we normally kept the locking pins in they were only removed at the order "prepare for diving. Note these handles were easy to grab accidentally in heavy swell for support, thus a an extra safety could be necessary. We used them all the time in peace time.
Tore

Don Prince · « **Reply #2920 on:** 21 Oct , 2015, 19:55 »

Hello Mr. Tore,

When MBT 2 and MBT 4 are in the RFO configuration, the external gate valves are shut leading to the common vent duct.

Question - do they shut the emergency vent valves on MBT 2 and MBT 4 also, or do they not matter since the gate valve is shut?

When MBT 2 and MBT 4 are in the RFO configuration, I believe the blowing valves for MBT 2 and MBT 4 are shut on the HP air distributor. That would allow the crewman to use the master blowing valve on the distributor to provide HP air to the other ballast tanks MBT 1, MBT 3, and MBT 5. Correct?

Did they ever somehow lock or disable the valves for MBT 2 and MBT 4 while in the FRO configuration on the blowing distributor; like remove the valve hand-wheel?

When MBT 2 and MBT 4 are in the water ballast configuration, then all the valves are open on the HP air distributor and the master valve provides HP air to all the ballast tanks. Correct?

Is there a reason to selectively blow ballast tanks?

Regards,
Don_

tore · « **Reply #2921 on:** 22 Oct , 2015, 01:59 »

Don.
I would shut the emergency vent valves in order to prevent fuel being forced into the venting duct.
I guess you are right in your assumption that the HP air distributing valves are shut to the MBT 2 and 4 as you normally only blow MBT 1, 3, and 5 in that configuration.
I don`t think we took any further actions except shutting the air distribution valves. The control room engineer was a responsible PO and usually the only person operating the blowingpanel and was knowing what he was doing.
I guess the individual distribution valves were provided for being able to compensate for major trimdeviations fi.waterintrusion. The volume of the air admitted to the tanks is depending upon the resistance (counterpressure, the variable depths) of the tanks and some MBTs are emptied faster ( using more air) than others thus it it convenient to compensate this by having selective blowing of the tanks and you get a very flexible system.
Tore

tore · « **Reply #2922 on:** 22 Oct , 2015, 13:40 »

Don.
On blowing the MBTs by exhaust you are even more susceptible to the resistance in the ballasttanks as you are blowing with much lower pressure than HP air. In extreme situations MBT 2 and 4 might take all the exhaust leaving it impossible to blow the other tanks as the exhaustgas escape via the saddletank Kingstons unless you are able to carry out selective blowing.
Tore.

Don Prince · « **Reply #2923 on:** 24 Oct , 2015, 22:15 »

Hello Mr. Tore,

I corrected all the issues that you pointed out. Previously, I did a word search but that will not find text in a graphic. Thanks for finding those errors... I uploaded a corrected version of Skizzenbuch to dropbox.

Regards,
Don_

tore · « **Reply #2924 on:** 25 Oct , 2015, 02:57 »

Don.
Checked your corrections OK.
Tore

Don Prince · « **Reply #2925 on:** 30 Oct , 2015, 22:38 »

Hello Mr. Tore,

While reviewing the latter part of Skizzenbuch, I find that there are several instanced where the starting lever is called a Starting handle and vise-versa. However, I believe both identifiers are correct...

If I place the following comment in Skizzenbuck, then do you agree that this will eliminate any confusion?

"Note: (ANLASSHEBEL = Starting Lever) - The lever has an attached grip/handle (ANLASSGRIFF = Starting Handle) and the handle must be squeezed in order to change the lever position; both are considered to be the same integral component. This same logic applies to all the levers on the diesel engine operating panel."

Regards,
Don_

tore · « **Reply #2926 on:** 31 Oct , 2015, 00:47 »

Don.
Yes, the handle is the last component of a linkagesystem consisting of levers and rods. You "grab" ( almost the same word in German "griff") the handle to move the linkagesystem.
Tore

Don Prince · « **Reply #2927 on:** 31 Oct , 2015, 21:32 »

Hello Mr. Tore,

I uploaded what I believe will be the last version of Skizzenbuch into Dropbox... I added a 6 page walk through of U-995 to the prologue to provide the reader with a physical reference point...

Regards,
Don_

tore · « **Reply #2928 on:** 01 Nov , 2015, 01:08 »

Don.
Your 6 pages tour of the U-995 is a good idea. What do you mean by NCO room?
Tore

Don Prince · « **Reply #2929 on:** 01 Nov , 2015, 15:26 »

Hello Mr Tore,

NCO = Non Commissioned Officer

tore · « **Reply #2930 on:** 02 Nov , 2015, 00:06 »

Don.
Shortcut on my side. The reason is that we normally used the name Petty Officers mess (PO mess) for this compartment and CPO mess (Chief Petty Officers mess) for the compartment between the wardroom and forward torpedo room. Your nomination should be OK.
Tore

David83 · « **Reply #2931 on:** 06 Nov , 2015, 03:17 »

Great new Book .

Hi Guys i want to point in here there is a great new book on the market about the Persicopes on german submarines at Company Carl Zeiss .
There is everything inside how it works ,technikal specs ,Drawings how the mechanic to rise and lowering the periscope works ,assembly of it ,factory pictures and many more .
you can get it via amazon or ebay .

maybe a good addition for the technical guys here

wbr David

SG · « **Reply #2932 on:** 06 Nov , 2015, 12:51 »

Great catch David, thank you for sharing it!

falo · « **Reply #2933 on:** 11 Nov , 2015, 22:11 »

Hi Tore,

I have a question concerning the two spare torpedo containers of the typseven/41 stored under the wooden deck (bow and stern) and the layout of the planked or slotted deck.

Please take a look at the attached picture: I have read that the late VIIC/41 had no spare torpedoes because of the continuous Royal Air Force threat it was a dangerous thus needless purpose. So when the spare containers (blue layers on the drawing) were removed, I suppose that the layout of the wooden deck was also fitted and the cutouts (red layers) vanished too?

The reason behind this questions is that the (well known) underlying drawings from Koehl/Niestle ("Vom Original zum Modell) are showing a late VIIC/41 with slotted deck and spare torpedo containers. The refueling bow is IMO a indication that this is a "late" VIIC/41, so the deck should be planked and the spare torpedoes removed. It is no reflection on Koehl and Niestle work – I suppose they drew a general plan and had to consider a wide range of different u boat modifications – it is just for my understanding.

Thanks in advance
falo

tore · « **Reply #2934 on:** 12 Nov , 2015, 01:09 »

Hi Falo.
U-995 was launched July 1943 and not fitted with torpedo containers in the casing but with wooden planking deck. The GA drawing from Koehl/Niestle is dated 1948 and shows a slotted deck, no torpedocontainers and four storage containers having hatches on deck. The containers as well as the wooden planking hatches were easy to remove and install. Below are some photos I took back in 1953 of the U 995 were you can see the wooden deckplanking. As far as I can see there are no wooden hatches for the torpedo containers, it might be two hatches used for storage of mooring equipment and a rubber dinghy as far as I can remember. I guess the wooden deck and hatches varied particularly towards the end of the war. In spite of the GA drawing of Koehl/Nietsle, the U-995 during the war did not have any storage containers in the casing, 2 containers were later installed by the Norwegian navy. Other Norwegian VII Cs had three and four containers.
Tore

falo · « **Reply #2935 on:** 12 Nov , 2015, 13:47 »

Hi Tore,

thank you very much for the information.

Regards
falo

Don Prince · « **Reply #2936 on:** 21 Nov , 2015, 16:17 »

Hello Mr. Tore,

I made some changes in the U-Boat dive angle drawings. The location of the aft hydroplane should be located very close to the rudders. Do you approve of my changes?

Regards,
Don_

Original...

Don Prince · « **Reply #2937 on:** 21 Nov , 2015, 16:18 »

Changes...

Don Prince · « **Reply #2938 on:** 21 Nov , 2015, 16:20 »

Changes....

Don Prince · « **Reply #2939 on:** 21 Nov , 2015, 16:22 »

Changes...

OldNoob · « **Reply #2940 on:** 21 Nov , 2015, 16:48 »

WOW didn't realize the diving angle was that steep.

Don Prince · « **Reply #2941 on:** 21 Nov , 2015, 22:29 »

Battery design...

The air entrance opening is designed in such a way that during a boat’s inclination up to 35° in any direction no acid is spilled from the cell.

tore · « **Reply #2942 on:** 22 Nov , 2015, 01:46 »

Don.
Diving angle and depth difference.
I am afraid you have misunderstood my sketches of illustrating the relation between diving angles and pressure differences (depths). On my first sketch (below) my idea was to show the Kingstons in MBT 3 marked green as an indication that the green marks are the free flood gates of the MBTs, meaning the points where the seawaterpressure set the differential hullpressure in relation depthdifference caused by the diving angle. So the green markings fwd. and aft are only markings of the freeflood areas of MBT1 and 5. as you know there are no Kingstons on these inlets. At even keel you would notice there is a higher pressure in MBT 3 than MBT 1 and 5. A practical consequence of this is that it would require more air per M3 tank volume to empty MBT 3 than MBT1 and MBT 5 at even keel. Under normal circumstances this would have impact when blowing the tanks by exhaust gases. You start to blow the saddletanks having the Kingstons at the highest position ( lowest counterpressure), continue blowing MBT1 and 5 having the next lowest counter pressure until you are that high up that your MBT3 gets an acceptable low counterpressure for the exhaust. Thus it is no attempt to indicate the position of the hydroplanes by green markings as they are irrelevant in this case.

Tore

tore · « **Reply #2943 on:** 22 Nov , 2015, 03:16 »

Quote from: OldNoob on 21 Nov , 2015, 16:48

WOW didn't realize the diving angle was that steep.

This is a crash dive angle which normally is not common. It requires some skill as you have to watch, what in the Royal Navy submarineservice is called the Duchess Ass, which is the ultimate aft end. If this part is too high above the surface you have a problem with the thrust of the propellers. The ideal angle is when the wind deflector on the bridge and the Duchess Ass is descending the seasurface simultaneously.
Tore

Don Prince · « **Reply #2944 on:** 22 Nov , 2015, 18:45 »

Hello Mr. Tore,

The labeling on the first drawing "Free Flood Gates" resolved the issue for me! I think it was needed to help the reader as well...

I uploaded the latest print version of "Skizzenbuch 11 x 17 - M" into dropbox...

Thanks you!
Regards,
Don_

tore · « **Reply #2945 on:** 23 Nov , 2015, 00:41 »

Don
Your last Skizzenbuch uploading is correct.
Tore

Don Prince · « **Reply #2946 on:** 25 Nov , 2015, 21:33 »

Hello Mr. Tore,

I have completely gone through Skizzenbuch for hopefully a last time looking for any words that should not be used when describing anything within a U-Boat. Those words which you have impressed upon my newly learned vocabulary such as closed/shut, dive tanks/ballast tanks, ventilation valve/vent valve (2 very different systems), flood valve/Kingston, dive plane/ hydroplane, and of course wench/winch. (Wench) Obviously we don't want women with loose morals on a U-Boat; except in a crewman's romantic dreams.

The only thing I don't have yet is the foreword written by Jak P. Mallmann Showell. I believe he wants to wait until the publisher produced an approved version of the book. He liked the book's general idea and format, but took issues with the German text, and perhaps my writing skills. I got help from Mark Hessburg with the German text, and I have attempted to improve my writing skills.

I have uploaded the version of Skizzenbuch 11 x 17 - M that I will send to Schiffer Publishing along with my Leather bound metal post binder to be used as a general layout guide for the publishing entry personnel.

Again, thank you for all your help with Skizzenbuch...
Kind regards,
Don_

NZSnowman · « **Reply #2947 on:** 25 Nov , 2015, 21:47 »

Quote from: Don Prince on 25 Nov , 2015, 21:33

I have attempted to improve my writing skills...

Hi Don,

I know that you mean

I have spend the last fours weeks writing, rewriting and some more rewriting my thesis for my Master's.

tore · « **Reply #2948 on:** 26 Nov , 2015, 00:00 »

Don.
I guess a book like yours is never finished, but I admire your stamina and courage to go through the whole process. Looking forward to seeing the complete book. Same goes for Simon, you two have contributed a lot to improve the understanding of the VIICs constructions and operation.
Tore

Don Prince · « **Reply #2949 on:** 17 Dec , 2015, 22:43 »

Hello Mr. Tore,

The regulation tank configured for the deep diving configuration discharges about 100 liters/10 meters when diving using the main drainage pump in the 2 stage configuration. The initial air pressure in that tank was set to 10 to 12 Kg/cm2, and the tank design is for a maximum of 14 Kg/cm2. While diving, the tank's internal air pressure will be reduced, but this is of no consequence. The opposite actions take place when the U-Boat ascends to periscope depth and the water is pumped into of the tank and the internal air pressure increases to the previous state.

If the dive was to escape an enemy depth charge attack, then I would head off in a desired direction to assure I escaped the surface vessels. Every once in awhile I would stop and listen to assure I'm not being followed. Then at some point, I would initiate a surfacing procedure. My reason for this thinking is that I don't want surface vessels waiting for me to bring the U-Boat up to a ramming depth or a shallow depth charge depth. If the U-Boat were coming up to the surface and the enemy was setting quietly waiting, then they could possible listen and hear the pumps taking water into the deep diving regulation tanks. Does my thinking make sense?

The regulation tank configured for the shallow diving configuration may take in water by allowing the tank to vent internally into the pressure hull, or remove water from the tank by increasing the tank's internal air pressure. I believe these maneuvers are done while running at periscope depth; they don't want to run the pumps and create noise.

When the U-Boat tanks are in the Reserve Fuel Oil configuration only one regulation tank is available, a Port and Stb saddle tank. I thought they could use one side for the deep diving configuration, and one side for the shallow diving compensation. Is that correct? Was there any preference as to which (port of stb) tank was assigned to the deep diving configuration?

Regards,
Don_

tore · « **Reply #2950 on:** 18 Dec , 2015, 00:50 »

Don.
Tne way of operating a VIIC during various attacks and counterattacks varies depending on the time and the technical development both with regard to the air superiority,Sonar and Asdic. On the net San Fransisco Maritime National Park Association you shall find the submarine commanders handbook ( U.Kdt.Hdb.)for a VIIC issued in 1942 in force as from 1943. You shall find the German Navys recommendation to the CO for maneuvering under various circumstances, including escape of a depthcharge attack.
I guess at that time the advice was to change depth dynamically by speed and hydroplanes not by using regulating tanks pumping or flooding and use the diminishing displacement without regulating to speed up matter. When required depth is obtained I guess you eventually had to compensate by careful pumping/blowing the regulating tanks depending upon the CO`s judgement.
When you are surfacing, you would use dynamic forces and not pump in regulating water, you rather use flooding without using the pump and venting the tanks inside the submarine. I guess I would use both tanks simultaneously preventing atworth list.
Tore

Don Prince · « **Reply #2951 on:** 20 Dec , 2015, 00:48 »

Hello Mr. Tore,

Is atworth list a roll or tilting effect? I google atwort list and I only find a location for Atworth in the UK...

Regards,
Don_

tore · « **Reply #2952 on:** 20 Dec , 2015, 02:31 »

Don.
I am afraid it`s a bad spelling for athwart, used for a list either to port or starboard .
Tore

Don Prince · « **Reply #2953 on:** 20 Dec , 2015, 13:23 »

Hello Mr. Tore,

Thank you for the info... No problem with the bad spelling. That's a problem that I have been dealing with for decades along with my dyslexia.

Regards,
Don_

tore · « **Reply #2954 on:** 22 Dec , 2015, 23:39 »

OldNoob · « **Reply #2955 on:** 23 Dec , 2015, 00:06 »

Nice artwork tore

Don Prince · « **Reply #2956 on:** 25 Dec , 2015, 10:08 »

Hello Mr. Tore,

Merry Christmas and Happy New Year to all... The best thing about the New Year is Old Friends!

Kind regards,
Don_

Don Prince · « **Reply #2957 on:** 25 Dec , 2015, 10:14 »

Hello Mr. Tore,

Is that a new paint program? The frame in your Christmas Card image is in a 3D format; Great job!

Regards,
Don_

tore · « **Reply #2958 on:** 25 Dec , 2015, 23:02 »

Don.
No it`s the same old programme, I just downloaded the frame from the net. Wish you all the best for the year to come hoping your Schizzenbuch would materialize.
Tore

SnakeDoc · « **Reply #2959 on:** 19 Jan , 2016, 03:07 »

Hi Tore,

I have got question about trim pump. I know, that it is electrically driven, two-cylinder, double acting piston pump with vertical worm shaft.
However, I'm not able to locate the pump cylinders.
Here:

I have uploaded two views of the pump. What are the two "bulbs" at the front? Are the cylinders located behind?

--
Thanks, regards
Maciek

tore · « **Reply #2960 on:** 19 Jan , 2016, 06:25 »

Maciek.
Good to have you back. The trim pump is as you say a double cylinder piston pump, I don`t recall it as a double acting though. The casings for the piston cylinders are difficult to see down behind, but what you see in the front of the pump are the two "bulbs" which are only two buffers (called airvessels) having an aircushion on the top to equalise the reciprocating pump pressure fluctuation in the water both to avoid pulses and noise in the pipeline. The two smaller "bulbs" are the Valvechambers for the suction/ discharge valve chambers. Unfortunately I don`t have a cross section drawing, but may be a cross section of the double cylinder coolingwater pump for the main engine will do for an explanation.
Tore

SnakeDoc · « **Reply #2961 on:** 22 Jan , 2016, 03:48 »

Hi Tore,

good to hearing from you.
Thank you for the answer.

On the drawing below I have tried to mark the components of the pump - in my
opinion at least.

Does it make sense?

--
Regards
Maciek

tore · « **Reply #2962 on:** 22 Jan , 2016, 06:36 »

Maciek.
I believe you have got the idea, anyhow for a singleacting pump, for a double acting pump it is a bit more complicated as you got to have crosshead to be able to utilize the underside of the piston which would imply a somewhat higher pump. It could be there is a mix up with a double pistonpump and a double acting pump.
Tore

SnakeDoc · « **Reply #2963 on:** 09 Mar , 2016, 08:19 »

Hi Gentlemen,

I hope you are doing well.

Here is the link the to the page, where is described story of the U534 conning tower replica:
http://www.modelartanddesign.com/page23.htm

Though U534 was type IXC U-Boat, I let myself to post this link in this sub-forum (

),
because one of the photos presents interesting technical detail: interior of the diving planes
(or main rudder) console:

And the photo of the renovated console:

--
Regards
Maciek

tore · « **Reply #2964 on:** 09 Mar , 2016, 10:14 »

Hi Maciek.
Doing fine thank you! Just renewed my driving licence which is not an easy job in this country when you are 87. In fact to day I feel I could go down to Kiel and crank up good old U-995 any time if she would float.
The tower of U-534 seems to have been excellently restored I am sure for a considerable price and the rudder/hydroplane console is a beauty however i don`t believe we had a two colour version, I guess the whole thing was dull grey. Even the handles and knobs were not shiny.

SG · « **Reply #2965 on:** 11 Mar , 2016, 08:49 »

Maciek, many thanks for the link: plenty of great shots. The console new look is outstanding too. And yes, doing pretty fine
Cheers
SG

falo · « **Reply #2966 on:** 17 Mar , 2016, 14:56 »

"In fact to day I feel I could go down to Kiel and crank up good old U-995 any time if she would float."

Hi Tore,
it seems that your old maid "Kaura" (Ex U-995) will be dressed up for your proposal: Please look at attached pictures, visited Laboe yesterday and have taken same photos. The deck section around the snorkel cutouts is covered by a tent. I suppose the upper pressure hull underneath the cutout is rusty and has to be renovate.You can recognize a compressor on pic "0014". IMO a sure sign that this section is provided for a accelerated drying.

Regards
falo

P.S: If you need a mate for cranking up U-995, it would be a honour for me to enlist as a volunteer under your command, Sir!

tore · « **Reply #2967 on:** 17 Mar , 2016, 15:42 »

Falo.
Thank you for sharing recent images of my old lady. I guess she needs some Botox to cover her wrinkles and scars. For all you guys who fancy canning, the light on falos photos reveals the susceptible platings for the saddleballast tanks 2 and 4. You clearly see the dents in those areas whereas in the pressure proof area of the Q, regulatingtanks 1 and 2 you hardly see any dents. Canning and denting is not only to start carving the hull and saddle, it needs knowledge where to put it as well. Excellent photos Falo.
Tore

falo · « **Reply #2968 on:** 18 Mar , 2016, 14:18 »

Hi Tore,

yes you are right your old lady needs a little make up, because she is a bit rusty (see attached pics "0009", "0013", "0026" and "0029".

I suppose preservation is very difficult because U-995 is not an indoor presentation like U-505 in Chicago. So the ravages of time won't reprieve the boat.

I haven taken two pictures in addition which assist your thinkings about model scale, rivets, carving, canning and denting. If you have look at picture "0006" (stern) you can recognize how small the rivets are. Picture number "0022" is a very rare one from the flood holes at eye level. You can see clearly the frames of the inner structure through the flood holes. The drip channels at the lower left side are not accurate because they just for draining the rain and dampness (as you've mentioned before).

Regards
falo

tore · « **Reply #2969 on:** 19 Mar , 2016, 01:35 »

Falo.
Interesting details of the present condition of U 995. Indeed an illustration of the small almost invincible rivets on the casing. The real steelrivets occur only in those area where you need strength like the riveted hatch for fitting the main engines into the pressurehull. I guess the majority of the corrosion damages of the pressurehull was done while she was laid up afloat almost five years prior to the Restoration. As you might see from the image below she was in bad shape at that time, having practically no antifouling and corrosionprotection. The casing was very susceptible to corrosion even in my time and as I have told before almost half the fwd starboard casing was swept away in a gale crossing the Northsea to Scotland in November 1953.
I still maintain my point of view, it is a pity that modelbuilders overdue the canning, rivets and the pressurehull corrosion inspired by the museum U 995 as an operational Uboat would never have such damages.
Tore

Don Prince · « **Reply #2970 on:** 20 Mar , 2016, 23:12 »

Hello Mr. Tore, Maciek, and All,

Maciek, I really like the photos of the BBC unit; a great find...

Skizzenbuch, seems to be going along OK with the publisher. I have not had any return emails or notices for issues with my original text file, or the printed Metal Leather Covered Post Binder Book (11 x 17).

During the past 30 days, I have gone through eye operations for cataracts in both eyes. I didn't realize my eyesight was that bad. However, while writing Skizzenbuch, it became more difficult to focus on my computer screen. When I first went to the eye doctor, they attempted to measure the thickness of the cataracts running down the center of both eyes with a light reflecting instrument. However, on one eye they had to use a device with water and sound (i.e., ASDIC/SONAR) to measure the thickness; it was that bad.

After the first eye lens replacement, it was amazing - I could see clearly and the colors, they were so bright and vivid. I could cover the now good eye and the other normal eye still had the wide cataract streak down the middle, but the other areas of sight was like looking through a glass of iced tea. I didn't realize my eyesight was so deteriorated over the years. Three weeks later, the other eye lens was replaced in the Laser Assisted cataract surgery. I was far sighted so I had the astigmatism corrective lenses installed which cost me $3330.00 total and worth every penny.

I will keep everybody updated on the Schiffer Publishing progress with Skizzenbuch...

Regards,
Don_

tore · « **Reply #2971 on:** 21 Mar , 2016, 01:26 »

Hi Don
Sorry to hear you had eyetroubles. I have been through the same thing and experienced no further troubles afterwards. I have been using the skizzenbook a few times and I miss an easy way to find what I am looking for. Would it be an idea to have a register?
Tore

Don Prince · « **Reply #2972 on:** 21 Mar , 2016, 17:22 »

Hello Mr. Tore,

I thought about an INDEX in the back of the book, but never got around to it. The CONTENTS on pages 4 and 5 generally get you into the ball park. If I need to search for something, I generally use the PDF edit tab and then use FIND to locate a specific word... Although, this is not an option for the printed book.

I just looked at the Skizzenbuch PDF with my new implanted lenses and it is really bright and colorful; I didn't notice that aspect before...

Regards,
Don_

Don Prince · « **Reply #2973 on:** 21 Mar , 2016, 23:58 »

Hello Mr. Tore,

I found a piece of free software which allowed me to build an index from Skizzenbuch... The file name is Skizzenbuch Index.pdf and I uploaded it to dropbox at the Skizzenbuch folder. Please let me know what you think and feel free to make any suggestions.

Regards,
Don_

tore · « **Reply #2974 on:** 22 Mar , 2016, 01:52 »

Don.
I just downloaded your index software and it seems to me it is exactly what I am looking for. Let me test it for a few days and I`ll give my comments if any. May you have a colourful Easter with your new lenses.
Regards
Tore

Don Prince · « **Reply #2975 on:** 22 Mar , 2016, 10:24 »

Hello Mr. Tore,

Glad to be of assistance... You certainly have an eye for the outstanding Easter image with the chocolate eggs and Kaura S309 in the magnifying glass...

Happy Easter to you and All,
Don_

tore · « **Reply #2976 on:** 23 Mar , 2016, 00:50 »

Don.
I have tested your index system a few times and have a few remarks. The idea is very good and very handy for f.inst. modelbuilders who can look up whatever item they require to get detailed information. However somehow the system does not pick up several important items as tanks , regulating tanks , ballasttanks, Q tank, negative buoyancytanks etc. Further fuel,trim,tower,vent, exhaust, pressurehull, rudder and several other important items are not picked up. The idea of an index would definitely be an asset if it is possible to improve same.

Tore

Don Prince · « **Reply #2977 on:** 23 Mar , 2016, 18:42 »

Hello Mr. Tore,

I created a new index file and uploaded it to dropbox... I have some limitation parameters when I search for words to index; no double words, and I set the word length to 3 letters or more. Q Tank may be found by just searching for tank. However, I added most of the words you suggested. What do you think of the latest index?

Skizzenbucvh 11 x 17 M1.Index

Regards,
Don_

tore · « **Reply #2978 on:** 24 Mar , 2016, 00:42 »

Don.
It is indeed better, however I guess somehow you have to get around the problem with double words as you get in excess of 100 pages containing, hull, tank, tanks etc. I have no idea how to overcome that problem, but I bet with your expertise you`ll find a way. I still think it is worth while, there are many out there looking for such a manual.
Tore

Don Prince · « **Reply #2979 on:** 24 Mar , 2016, 19:16 »

Hello Mr. Tore,

I spent more time with the index generator and I have created a much better index with linked words. The only thing I can't get around is the "Q Tank"... I would need to use a 1 letter search and every word in the book would appear as a index optional entry. However, I did get Negative Buoyancy Tank as an entry...

The latest file uploaded is INDEX.pdf... How does this one look?

Regards,
Don_

tore · « **Reply #2980 on:** 25 Mar , 2016, 00:54 »

Don.
Again an improvement, however f.inst. if you are looking at the word bow you get almost 50 pages with the word bow, of which more than 2/3 are containing "unimportant" words like bow vents, bow tanks etc not really the bow itself. I guess more than 10-15 pages containing the relevant word makes it a bit cumbersome to use, it would be an advantage to get rid of this problem f. inst. by making a search instruction like if you want an info on the bow design like Atlantic bow, bow flare, bow hawser etc you use linked words to limit the pages. I guess by checking all the words giving a search result of more than 10-15 pages it might be possible to find a system to overcome this problem. It exists probably a solution made by others somewhere out there as it ought to be a common problem I guess.
Tore

Don Prince · « **Reply #2981 on:** 25 Mar , 2016, 12:56 »

Hello Mr. Tore,

It looks like I can get around most of the issues you have brought up by refining the word list to multiple words instead of one word. I have incorporated many of your suggestions in the latest uploaded INDEX.pdf to dropbox. I even did a separate index project with 1 letter and created a two word index for Q Tank/Q Tanks, then I copied it into the final Word/PDF files...

Regards,
Don_

tore · « **Reply #2982 on:** 25 Mar , 2016, 23:47 »

Don.
Much better and very usable. Somehow a few items like Papenberg, IMO, Roots (blower), galley,MAN, Krupp Germaniawerft are missing whereaes you got f. inst. Telefunken. It could be many more of course, may be you are able to fix this and you`ll have an approved handy system.
Tore

Don Prince · « **Reply #2983 on:** 26 Mar , 2016, 18:31 »

Hello Mr. Tore,

I spent several hours going through the index and eliminated most of the long page entries with further word extensions. However, I did leave a few of the long page entries because this was pertinent data. I believe the latest INDEX.pdf in dropbox looks fairly usable with all your help. Thank you sir for your expert assistance...

Regards,
Don_

tore · « **Reply #2984 on:** 27 Mar , 2016, 00:07 »

Don.
I guess you got the index solution. The Skizzenbook has become an unique hand book for everybody who wants to dive into details of the VIIC`s. Most of the questions raised over several years in my mailbox would be answered by your book I look forward to seeing the final printed result.
Tore

Don Prince · « **Reply #2985 on:** 27 Mar , 2016, 16:00 »

Hello Mr. Tore,

I went through Skizzenbuch and refined the index to the point that I believe this will be the final version which I uploaded to dropbox. I also look forward to seeing the Schiffer Publishing version of Skizzenbuch.

Regards,
Don_

tore · « **Reply #2986 on:** 30 Mar , 2016, 08:04 »

I sometime get questions on the emergency escapes from U boats.
In general I can can only say the survival statistic is not very impressive and I only know about a handful successful attempts of the German boats. In the last accident in the RN I remember in my time the RN T class submarine HMS Truculent which collided with the Swedish tanker M/S Devina at the entrance of the Thames January 1950. There was quite a number of people on board as she had some yardpeople in addition to the normal crew. I guess some 57 people managed to surface but were taken by the strong tidal current and perished in the cold water some 20 were picked up. The escape is one thing, but survival on the surface depends on what kind of support is available. The WW2 standard of escape equipment was by no means comparable to to days standard.
In general the VIIC`s pressure hull is divided into 4 separate pressureproof compartments, the control room separated by pressureproof bulkhead from aft and fwd compartments and conningtower separated by the pressurehull including by lower tower hatch. In addition you have the aft torpedo- and E- room, main engine room, the compartment consisting of galley and PO messroom, the compartment consisting of the sonar,radio, wardroom and CPO mess, and forward torpedoroom separated by watertight bulkheads. The watertight bulkheads have doors a bit low from the upper part of the pressurehull and the pressure hullhatches are equipped with a coaming.
In the event of an emergency escape, the lower doors and coamings all keeps the residue air in the compartments stable when flooding. The whole boat has to be flooded and the pressure tight compartment shut. You have now three separate escapehatches of which all if possible should be used as you have limited escape time, both with regards to pressure (bends) and chlorine gas emission from the flooded batterycompartments. When the uboat is flooded you pull down the escape hatch coamings lengthenings trunks which now ends submerged in the floodwater as the pressure equalizes with the ambient seawater pressure, at the same time the watertight bulkheads keep the trapped pressurized compartmentair up towards the pressurehull.
The crew is ordered to put on the Draeger breathing- and escape vest. This equipment is used both as and breathing apparatus or as an ascend/lifevest having an oxygen canister and a hydrosodium cartridge for CO2 absorption. In case of excessive chlorine gases the vest is used as a breathing apparatus otherwise the crew is waiting above the waterlevel breathing the trapped compressed compartmentair. A man dives under the hatchcoaming up to the escapehatch which now can be open as the pressure inside the u boat is the same as the ambient seawaterpressure. He has to be aware of the danger as the trapped air in the duct escapes as the hatch might slam shut when the airbubble collected at the top escapes. Now the waiting crew can take a deep breath of the compressed compartment air, dive under the coaming and have a continuous column of water up to the surface. While ascending the crew has to exhale all the time to let the compressed air out otherwise you might experienced a lungburst. Usually you are told to start whistling when escaping and due to the risk of "bend" you should adjust the ascendspeed ( by adjusting the air in the Draeger vest) to that of a small following airbubble. Normally a successful escape depends on the support you get on the surface almost everybody needs a decompression chamber treatment. The effect of having a human body exposed to high airpressure might be compared to a sodapop bottle, as long as it is kept under pressure it stays calm, but when you open the cork it start bubbling. The same happens to the human blood and can cause a fatal embolism hence you have to release the ambient airpressure slow ( in a pressurecamber).

Don Prince · « **Reply #2987 on:** 30 Mar , 2016, 19:45 »

Hello Mr. Tore,

Excellent information; thank you for sharing your years of knowledge and experiences, and please continue to do so...

Regards,
Don_

tore · « **Reply #2988 on:** 31 Mar , 2016, 00:39 »

Escape equipment.
Further to my yesterdays post I may enlighten you a bit on the escape hatch details and coaming. The main escapehatch would be the upper conningtower hatch and the lower conning towerhatch having a permanent coaming ending in an expandable lengthening which could be pulled down to some 1650 mm above the controlroom floorplates . I guess this expansion coaming was originally made of 3mm sheetplates, however in my time we used a canvas trunk normally stowed up toward the permanent coaming as can be seen on the image below. As can be seen on the image they have removed the expandable coaming on to days museums U-995 and put a grating over the hatch opening.
As previously stated when flooding the tower, air shall be compressed and trapped towards the conningtower top hatch. By opening the hatch this air shall escape causing a pressure fluctation which might slam the hatch shut. The hatch is provided with a catch normally to protect it from being flung open by the normal overpressure in the boat, this catch now allows the hatch just to open a crack to release the air. In addition you have a small checking cock which could be used for venting the air, however it is too small for practical use.
The time you are exposed to high airpressure ( the trapped air) is crucial with regards to bend and you have to reduce same by make the flooding and waiting time for the escape as short as possible.
Tore

tore · « **Reply #2989 on:** 02 Apr , 2016, 01:27 »

A well known discrepancy between the real VIIC and the Revell building kit 1:72 is the position of the anchorbay, which Revell has placed app. 1,5 frames aft of of the real design. As seen on the modell kit the anchor would hit the fwd. hydroplane when lowered. Accurate modelbuilders would have to replace the anchorbay approximately one frame ahaed of the centerline of the fwd.hydroplane guard.
On the museum U 995 they have done another modification by introducing, for some unknown reason, a stopper for the anchor fluke, see image. As so many other details on the museum U-995 this should not be introduced on an accurate model.
Tore

tore · « **Reply #2990 on:** 03 Apr , 2016, 03:36 »

As probably known, the Royal Norwegian Navy took over 4 ex German uboats after WW2. Three of these were VIICs. Early 1960 we had plans to modernize the VIICs and KNM KYA ex U-926 was partly converted. Below is an image of the submarine after getting a new sailtower. An interesting detail is that the old hinged schnorchelmast was kept in a new homing in the sailtower thus no telescopic schnorchel.

Tore

SG · « **Reply #2991 on:** 03 Apr , 2016, 08:40 »

Thanks for the information about the correct position of the anchorbay, Tore (and about all the other untold-before details). You're a gold mine, Sir. I'd suggest to celebrate the 200th page in your thread, it's quite an achievement!!!

tore · « **Reply #2992 on:** 04 Apr , 2016, 02:38 »

I have been involved as a VIIC and IXC technical adviser for a Canadian fiction author writing a WW2 uboat novel on uboatoperations in the Artic. In this connection I have tried to advise the author about the sonar mirror layer which you experience in these waters.
Apart from the problems of operating a VIIC under the polar ice, you have the well known WW2 submarine trick of hiding under the sonar reflection layer. In my time we had problems with unidentified submarines operating in the deep Norwegian fjords, like the Swedes we never caught one. Our theory at that time was that somebody used the fjord for training submarine COs of hiding under the sonar reflection layers which was quite frequently existing in the fjords. When rivers from the mountain lakes ends up in the salty fjordseawater it creates a layer of different salinity, eg. gravity, which reflects the sonar beams and hence acts like a sonarmirror protecting the submarine. If you in addition are able to stay dead silent under such a layer you would be fairly safe as neither the active sonar nor the hydrophones would pick up anything. However it requires some skill to place the submarine in such position. When you have found the layer by taking temperatures and watersamples, you used the regulating tanks to adjust accurately the submarine to neutral buoyancy, shutting down almost everything, placing the boat under the reflection layer. By topping up the hydraulic system on beforehand you are able to silently adjust the minor variation in buoyancy by lowering and raising the periscopes by using the hydraulic accumulators thus silently adjusting the displacement and buoyancy. This required some training and we were in my time of the opinion our fjords were used for that purpose.
Tore

Don Prince · « **Reply #2993 on:** 09 Apr , 2016, 00:16 »

Hello Mr. Tore and All,

While I was working on the INDEX FILE file I discovered 19 duplicate words with different spellings in the index generator file??? IN other words wrong spellings! I corrected the spelling errors and uploaded the latest Skizzenbuch 11 x 17 - M.PDF file into dropbox and the INDEX FINAL.PDF...

Regards,
Don_

tore · « **Reply #2994 on:** 20 Apr , 2016, 03:00 »

Don.
Finally the site is back. My reply to you disappeared in the commotion. I had a quick glance at your last index and it seems OK to me.
Tore

Don Prince · « **Reply #2995 on:** 21 Apr , 2016, 14:13 »

Hello Mr. Tore,

Do you remember about a year and a half ago when I had a wrong understanding about the Regelzellen external fuel oil saddle tank. I believed the saddle tank was open at the bottom which allowed the fuel oil to be pumped in and float on top of the sea water in the tank; as the fuel oil was consumed/burned the water level would rise in the tank. At that time, the only issue I had was what stopped the tank from being dumped in rough seas with an open bottom?

In the first chapter of "Type VII U-Boats" around page 16 this was stated as the self-compensating fuel Oil tank design open at the bottom to the sea. Originally, I got that idea from a German U-Boat web site, so I don't know which started that design idea. It looks like that wrong idea was put forth because there was no experienced U-Boat EO to explain the actual Header Tank Water Compensating System and the Regelzellen tank design which was backed up with the actual Type VIIC U-Boat engineering drawings!

Experience definitely comes in handy...

Regards,
Don_

tore · « **Reply #2996 on:** 22 Apr , 2016, 01:12 »

Don.
I cannot specificly remember the discussion, but the system works as follows. The regulating and fueloilbunker tank 1 stb and port are as you are saying, external saddle tanks. They are not watercompensated as the normal fuel tanks and as the capacity is limited to 4.700 m3 each, the surface effect is small. As fueltanks they are filled like the other fueltanks but instead of forcing the compensatingwater out of the tanks you can either drain the residue water, if any, by the ballastpump or/and vent the tank through the mufflers in the controlroom. As you see from my image below the tanks are connected to the fuelsystem as any other fuelbunkertanks but as it is no compensatingwaterpressure to squeeze out the fuel, you transfer same by airpressure supplied by a LP air (0.5 bar) pipe to the tank, as an alternative you might even use the spare luboilpump in the engine room to transfer the fuel as can be seen on the image.
It goes without saying that when the regulating tanks are switched back to regulatingtank configuration, the tanks are contaminated by fuel which might leave an oilslick when in use. That is the reason why the regulating tanks are able to discharge the regulatingwater into the MBT3 while submerged keeping it on top of the MBT waterlevel until surfacing.
Tore

Don Prince · « **Reply #2997 on:** 29 Apr , 2016, 16:20 »

Hello Mr. Tore,

I have some questions about the early Type VII U-Boat that had the stern torpedo tube mounted in the upper deck area In that configuration:

1. Could they only launch the stern torpedo while submerged and not while surfaced?
2. While submerged did they use the piston to launch the stern torpedo as to not create air bubbles to give up the U-Boat's location?
3. Was the gyro angle set in the stern torpedo, or was only a straight shot configuration available?

Regards,
Don_

tore · « **Reply #2998 on:** 30 Apr , 2016, 00:18 »

Don.
As you know I am not a torpedoman, in fact I stayed away from it as much as I could, I guess Maciek is the right guy for answering your question. In my time we never fired a real shot with the aft torpedotube. I cannot see anything which should prevent you from launching a torpedo both submerged and surfaced, and using a piston the same way as in the forward tubes. We occasionally tested the launching bubbles usually in surfaced condition using a dummytorpedo as can be seen from a photo I took back in 1953 outside the submarinepen in Trondheim. Not much of lauchingbubbles as far as I can see. The setting of the gyroangle I am afraid I have to leave to Maciek.
Tore

SnakeDoc · « **Reply #2999 on:** 30 Apr , 2016, 03:39 »

Hi Gentlemen,

Don, you have asked interesting questions regarding the aft/external torpedo tube on the first version of the type VII U-Boats, known later as type VIIA.

Quote from: Don Prince on 29 Apr , 2016, 16:20

1. Could they only launch the stern torpedo while submerged and not while surfaced?
2. While submerged did they use the piston to launch the stern torpedo as to not create air bubbles to give up the U-Boat's location?
3. Was the gyro angle set in the stern torpedo, or was only a straight shot configuration available?

I have researched this topic some time ago and I think I have the answers to two of them.
Based on the Schussmeldung from torpedo attack conducted on 6th December 1939 by U31 (on Estonian merchant Agu), I can say, that torpedo was fired from aft torpedo tube, on the periscope depth (13,5 m), with the gyro angle 61,5 deg.
Regarding the piston, I do not have any direct information, but I suppose, it was also used in case of external torpedo tubes.

--
Regards
Maciek