SUBSIM Kiel meet

[Catfish]

Hello again,
some more photos, the rest can be viewed or downloaded via the dropbox link at the end.


Once more the observation perisope down in the control room, we were wondering why there are two oculars.. anyone?




The "Weihnachtsbaum", or christmas tree. The black shaft at the left turns the antenna, when extended.




Engine compartment with view aft, intake and exhaust valves above:




Switching table for the starboard electric engine:




All other photos i made are here:

https://www.dropbox.com/sh/4sra8zknp...Lh2jLqzza?dl=0

Best wishes,
Catfish

[Onkel Neal]

Cathfish!

[Catfish]

^ I knew i forgot to delete something

[Jimbuna]

Originally Posted by Catfish

^ I knew i forgot to delete something

Currently talking with Neal and I told him you look a little like u_crank

[Aktungbby]

Originally Posted by Catfish

Once more the observation perisope down in the control room, we were wondering why there are two oculars.. anyone?

From your own site: http://www.tvre.org/en/aiming-with-the-periscope

In the control room of the U 995 (located in the Laboe type VIIC U-Boat converted to museum-ship) is installed the type ASR C/13 (Angriff-Sehrohr) periscope. This is post-war periscope designed by Zeiss, based on the war-time type ASR C/6 periscope, which was designed for type XXIII U-Boats. This periscope consisted of the ocular box of type NLSR C/9 night periscope and periscope head of the type StaS C/2 attack periscope. The ocular box of the type NLSR C/9 night periscope was fitted with additional optical system (kind of telescope), which made possible reading of the bearing while looking through the periscope. The bearing scale was visible in the upper part of the view field. This optical system consisted of prisms and lens, and transmitted the view of the bearing scale through the slit in the periscope collar to the ocular box interior. Type ASR C/13 periscope which can be seen in the U 995 control room comes most likely from the U-Hai or U-Hecht (ex U 2365 and U 2367 respectively) and was installed on U 995 in the time when (most likely) she was converted to the museum-ship (during her service in the Royal Norwegian Navy as KMN Kaura, in the control room was installed the original type NLSR C/9 periscope).
The ocular box of the type ASR C/13 periscope is simplified version of the type NLSR C/9 periscope ocular box. It is slightly smaller, however the layout of the oculars, knobs and levers is the same. The ocular box is not fitted with the optical system for showing the bearing scale in the view field (the system was probably abandoned to make the manufacture simpler, faster and cheaper). The current periscope bearing is indicated by indication line, engraved on the periscope tube. It points the current bearing at the fixed azimuth circle. That's why type ASR C/9 periscope is fitted with only one azimuth circle, with 180° mark directed toward to the bow (please note, that azimuth circle in the U 995 control room is not properly set relative to the U-Boat longitudinal line). Over the fixed azimuth circle, the deflection angle ring is located, which is used in the same way as in case of previously described periscopes.

Backside view The cross-section of the type NLSR C/9 periscope ocular box (the optical system for transmitting bearing scale is visible)

[Eichhörnchen]

This is the best thread... wish I'd been there too Maybe next time. Nice to finally see your picture, Catfish (and Schroeder)

[Catfish]

Originally Posted by Aktungbby

From your own site: http://www.tvre.org/en/aiming-with-the-periscope

From the side i posted, eh? Well i read it, but i still thought it was something else. But it isn't
I thought there was a kind of rectangular "box" over both oculars, seems i looked at the wrong side
Thanks for posting this once more, so Einar and Oscar will finally know what it is for.


Does Dan "Elanaiba" read this, too? I am trying to find out where the switches for the clutches of the electric engines are, we both did not find it. But we will.

German boats were quite simple and not Diesel-electric, like the US ones.
So the Diesels had to be installed inline with the propshafts, not scattered all over the place and just feeding the batteries, driving the boat.

Basically it is like with all old "Tauchboote" with Diesel propulsion, you use the Diesel engines for running surfaced, and the electric ones for running submerged. You charge the batteries with the Diesels.
In the 'normal' german boats the electric engines also served as generators, so you did not need additional dynamoes or alternators (not in the IXd1/2/42 and XXI/XXIII types though, they were already different).

You could also use all kinds of combinations. The whole layout is quite simple, but versatile and practical, there are clutches to use and combine all components independently:

- You could run the Diesels alone, coupled straight through the propshafts for moving the boat surfaced (or submerged with a snorkel)
- ^ coupling the electric engines in generator mode to the propshafts driven by the Diesels, thus charging the batteries but reducing overall speed a bit
- Run both Diesels and couple the electric engines on the propshafts driving them directly together with the Diesels, adding a few knots to overall speed, but draining the batteries fast
- Uncouple the rear propshafts with the propellers, switch electric engines to generator mode and couple them to the parts of the propshafts driven by the Diesels (dead in the water then)
- Use one Diesel to drive the boat and the other for charging
- Use one Diesel for running, while maintining/repairing the other Diesel, this way you can either:
a) charge the batteries by driving the electric engines in generator mode coupled to the propshaft driven by the one Diesel
b) charge the batteries by coupling the electric engine in generator mode, of the stopped Diesel side, to the moving propshaft, driven by the propeller moving through the water, Diesel clutch on this side is then uncoupled
or both a) and b)

Does that make sense? Anyway we were looking where all the switches and clutches were

[Onkel Neal]

That does make sense.

Do you remember the discussion we were having about the ballast tanks?

I am still trying to find online documentation that explains the saddle tanks/main ballast tanks/negative tank.



Cutaway illustration

Illustrations never show the saddle tanks in detail. But this one shows 81 - Main immersion tank and 93 - Main fuel tank

and this illustration shows the MB#3 below the control room, like the illustration outside of U-995. On the third section, it lists "MB and RFO Tank 2 Port", is that inside the saddle bulges? I think you were saying that the saddle tanks are one long "tank" with baffles to separate the sections, is that right? So the MB2 and MB4 are contained inside the saddle bulges...?

And of course it shows MB#5 in the center bow, which I would assume is flooded before the stern tank to get the bow down.

There is a "Neg.Buoyancy Tank Port". If that is the "negative" tank (or tanks, one on each side I suppose), that sure seems like a small tank to get you down quickly.

I'm tempted to build a time machine just to go back and answer these questions.

[Catfish]

^ I'd come with your time machine, but minus the depth charges please

"Untertriebszellen" would be something like negative buoyancy cells, maybe to break the surface energy (but i doubt this plays a major role), but in any case to minimise the diving time.

Afaik a usual VII type boat had two of those, located near (left and right of the ballast tank 3, or main ballast tank) the control room, at the center of gravity of the boat. They were operated together, though Werner in his "Iron coffins" speaks about flooding the "fore part" only(?), to increase the diving angle faster in case of a dive. This may be wrong though, Werner's book is more of a novel than a real report, and has been criticized for a lot of wrong technical descriptions. The man "Werner" seems to have never existed, though the man using this pseudonym knew "a bit" about U-boats.

As soon as the U.-cells are flooded, the boat is running with closed upper venting valves, to be able to blow them asap after diving. In case they cannot be blown immediately after the sail submerging, the boat is in danger to "fall through" and get too deep, out of control.


From the "Tauchvorschrift für Unterseeboote":

Untertriebszellen

131. Bei Booten mit Untertriebszellen wird wie folgt verfahren: Die Untertriebszellen werden, wenn das Boot alarmtauchklar ist, über Wasser gefüllt gefahren, so daß dem Boot ein der Größe der Zellen entsprechender Untertrieb gegeben ist. Nach der Ausführung des Befehls „Fluten“ und merklicher Falltendenz werden die Untertriebszellen auf den Befehl des L.I. „Ausdrücken“ ausgedrückt.

(131. If the boat has negative buoyancy cells, the procedures are as follows: The U.-cells are being flooded when the boat is running surfaced, and in "ready to submerge" state (edit: alarmtauchklar=all men at diving positions, boat prepared for emergency dive - so .. usual condition in enemy waters), so that there is an appropriate negative buoyancy. After execution of the order "Fluten" (edit: flood the tanks!) and a perceptible tendency of falling, the cells are being blown out by order of the LI (Leitender Ingenieur).

Der beste Zeitpunkt des Ausdrückens für mittlere Boote ist eine Tiefe von etwa 8 bis 10 m, für große Boote eine Tiefe von 10 bis 12 m. Erfahrungsgemäß beruht die Wirkung der Untertriebszellen in erster Linie im schnelleren Durchbrechen durch die Wasseroberfläche beim Tauchen. Da die schnelle Erreichung großer Tiefen fast ausschließlich von der Lastigkeit und der Fahrtstufe abhängig ist (etwa 25 bis 30°, 2 x G.F.), ist es falsch, die Untertriebszellen auf größerer Tiefe auszudrücken, da der äußerst geringe Vorteil in keinem Verhältnis zu der Gefahr steht, in die das Boot in einem solchen Falle geraten kann. Insbesondere steigen der Luftverbrauch und die Ausdrückdauer ganz erheblich.

(The best time for the blowing ballast of boats of middle size is a depth of 8-10 meters, for big boats a depth of 10-12 meters.
From experience the essential effect of the U.-cells is one of breaking through the water surface during a dive. Because the reaching of greater depths is almost entirely dependent of angle and speed (ca. 25 to 30°, 2x all ahead) it is wrong to blow them out at greater depth, because the advantage would not be in due proportion to the danger, the boat will be in. Especially wastage of air and the time of the blowing ballast increase badly.)

132. L.I.: „Ausdrücken“.

Daraufhin wird das Ventil „Ausdrücken Untertriebszellen“ aufgerissen und mit höchstmöglichem Druck (20 bis 30 at) ausgedrückt. [...]


(132. LI: "Blow ballast".
With this order the "Blow U.-cell" valve will be torn open, and be blown out by the utmost pressure (20-30 at). [...]

The general procedure was to have the U.-cells being fully blown at 19 meters of depth.

From the plan you posted you can see the the one big main air induction tube coming from the conning tower and ending at the centered valve in the engine room above our heads, which had to be closed when diving. The two smaller wheels near it at the sides were for the closing/opening of the two exhausts, which had to be thoroughly maintaind for closing properly. Diesel exhausts and carbon used to build up on the valve surfaces, so they had to be sanded and polished regularly. I guess we spoke about that too, but..

All the best,
CF

[Onkel Neal]

Originally Posted by Catfish

Afaik a usual VII type boat had two of those, located near (left and right of the ballast tank 3, or main ballast tank) the control room, at the center of gravity of the boat. They were operated together, though Werner in his "Iron coffins" speaks about flooding the "fore part" only(?), to increase the diving angle faster in case of a dive. This may be wrong though, Werner's book is more of a novel than a real report, and has been criticized for a lot of wrong technical descriptions. The man "Werner" seems to have never existed, though the man using this pseudonym knew "a bit" about U-boats.

Wait, what? You're saying Herbert Werner was not a real captain?

https://en.wikipedia.org/wiki/Herbert_Werner

[Catfish]

Originally Posted by Onkel Neal

Wait, what? You're saying Herbert Werner was not a real captain?

https://en.wikipedia.org/wiki/Herbert_Werner

Umm, well, i do now believe he really was a U-boat-'Kommandant', however i was not so sure some time ago, and you, too:
http://www.subsim.com/radioroom//arc.../t-167387.html


Looking at this thread of a bygone time, i wonder where a lot of those subsim members are hiding now

[elanaiba]

Originally Posted by Catfish

Once more the observation perisope down in the control room, we were wondering why there are two oculars.. anyone?

Hey guys! Very nice to meet you all - and of course to see U995 again I was especially happy to see the attention the HMS Marulken devs paid to everything! Oscar (Oskar?) asked in-depth questions and clearly had the drive to truly understand things, the kind of drive I see in the best technical oriented game designers! I think the future is bright

I'll post my pics too in a while, though this time I was not really shooting much and I was careless with the pics

Regarding the periscope question, I found something interesting in the British "Report on HMS Graph" (captured U570) - http://www.uboatarchive.net/U-570/U-...tishReport.htm - page 32

Zeiss Periscope No. 2523 (Watchkeeping Periscope)

Optical Data

Optical length 7 m. 55.

Main eyepiece:
Magnifications 6.1 and 1.54.
Angular field
High power
7° 15' vertical.
8° 46' horizontal.
Low power
29° 2' vertical.
36° 38' horizontal.
Exit pupil 7.0 mms.
Eye clearance 1.5 in.

Second eyepiece:
Angular field
High power 7° 3' circular.
Low power 28° 36' circular.
Eye clearance 0/75"
Elevation movement to 90°
Depression movement to 10°

So, as far as I read, one of the eyepieces presents a round image that can be raised up/down to check the sky, and the other one presents a ellipsoid image that is fixed?!

I haven't looked closely but think this might be of interest: http://www.uboatarchive.net/U-570/U-570Plate27.htm

Dan

[Catfish]

Originally Posted by elanaiba

[...] Regarding the periscope question, I found something interesting in the British "Report on HMS Graph" (captured U570) - http://www.uboatarchive.net/U-570/U-...tishReport.htm - page 32 Dan

Thanks Dan !


I think (not sure!) it is what Aktungbby posted from my own link:

"The ocular box of the type NLSR C/9 night periscope was fitted with additional optical system (kind of telescope), which made possible reading of the bearing while looking through the periscope. The bearing scale was visible in the upper part of the view field. This optical system consisted of prisms and lens, and transmitted the view of the bearing scale through the slit in the periscope collar to the ocular box interior. Type ASR C/13 periscope which can be seen in the U 995 control room comes most likely from the U-Hai or U-Hecht (ex U 2365 and U 2367 respectively) and was installed on U 995 in the time when (most likely) she was converted to the museum-ship (during her service in the Royal Norwegian Navy as KMN Kaura, in the control room was installed the original type NLSR C/9 periscope).

The ocular box of the type ASR C/13 periscope is simplified version of the type NLSR C/9 periscope ocular box. It is slightly smaller, however the layout of the oculars, knobs and levers is the same. The ocular box is not fitted with the optical system for showing the bearing scale in the view field (the system was probably abandoned to make the manufacture simpler, faster and cheaper). The current periscope bearing is indicated by indication line, engraved on the periscope tube. It points the current bearing at the fixed azimuth circle. That's why type ASR C/9 periscope is fitted with only one azimuth circle, with 180° mark directed toward to the bow (please note, that azimuth circle in the U 995 control room is not properly set relative to the U-Boat longitudinal line). Over the fixed azimuth circle, the deflection angle ring is located, which is used in the same way as in case of previously described periscopes."

The layout can be seen in a cross section here:
http://www.subsim.com/radioroom/show...&postcount=100

[Catfish]

Just found that, on their site:

"All Type VIIs were attack boats with a single-hull design – which is to say the pressure hull is also the outer hull (wrong, all were two-hull-boats). To withstand sea water pressure up to a crush depth of 250 meters, the pressure hull was further reinforced with strengthening steel ribs inside the hull (? i think those rings were outside of the inner pressure hull?). Ballast was provided by several ballast tanks situated internally and externally of the pressure hull. The main tank was just below the control room, inside the pressure hull. Outside the pressure hull, external tanks were fitted at the bow and stern. These tanks however did not provide sufficient capacity, so additional saddle tanks were fitted to the sides of the hull. Diesel fuel tanks were situated inside the pressure hull (also, but not only - fuel saddle tanks) to avoid leakages during a depth charge attack. The earliest variants were also fitted with serrated net cutters on the bow, a specification carried over from World War 1 boats, but these were quickly discontinued"

It really takes some effort to put so many mistakes into one paragraph