Tores mailbox VIIC and VIIC/41 operation and technical details

[Don Prince]

Hi Simon,


I don't have anything to prove there is a wire mesh above the vent for the Type VII, but I believe there was.  Your, 2D drawings show the mesh.  I do have a quad-vent valve set for the Type IX that has the mesh.  I got that from Maciek...


Regards,
Don_

[Don Prince]

Hello Mr. Tore,


I change the Oil and filter on my car every 3,000 miles...  Do you remember how often they changed the 2 lube oil filters on the Type VII C diesel engines?


Regards,
Don_ 

[Don Prince]

Hello Mr. Tore,


Your opinion about the text and diagrams...


Regards,
Don_


"Lower Left - The return of the lube oil from the diesel engine can be switched to either of the lube oil system tanks (port or starboard). In the case of contamination (possibly seawater) you are able to isolate and clean the contaminated oil. This system is based on a lube oil centrifuge cleaning system which was removed on the later VIICs. However, you are  able to draw lube oil from either of the system tanks by using the fuel transfer pump as a spare lube oil pump as indicated on the image below.


Lower Right - The original centrifuge system had two pumps, one for dirty lube oil from the system tanks to the centrifuge and one for supply of clean oil from the centrifuge to the system tanks. On the later lubricating oil two (2) larger oil filters eliminated the need for the centrifuge purifier and the pumps. I don`t have a system sketch of the later system showing the exact location of the filters. However, the photo shows the two (2) filters in close proximity of the engine control panel. The hand pump mounted on the aft engine room bulkhead is used to dump contaminated oil overboard from either of the system tanks or the dirty oil tank.


Blown Head Gasket


Engine misfire with a gasket head-to-head leak causes lowered compression which results in a rough idling engine. Damage of this type may not cause overheating, coolant in the oil or any other outward sign. Overheating from a blown gasket when a head gasket fails between a combustion chamber and the cooling system, a loss of coolant and overheating are often the result. Oil in the coolant and coolant in the oil; head gaskets may also fail between the coolant passages and the lubrication system. This type failure may show up as oil in the coolant or coolant in the oil. Unfortunately, this failure will destroy the ability of the oil to lubricate and change the viscosity of the oil. The results could be a ceased up diesel engine."

[tore]

Tore, Don, & Maciek.

Q. Would there be a wire mesh over the opening for the MB3 valve? (I just noted there a dotted line above the opening of the MB & RTO Tank, which has a wire mesh over the opening. There no dotted line above the opening MB3 valve ) http://www.uboatarchive.net/U-570/U-570Plate28.htm

Q. Was there a gasket on the venting valves, or just metal on metal?

Simon.
I believe the MBT3 vents had a protecting wiremesh on top. I  think the vent seatings were metal to metal.
Tore

[tore]

Hello Mr. Tore,


I change the Oil and filter on my car every 3,000 miles...  Do you remember how often they changed the 2 lube oil filters on the Type VII C diesel engines?


Regards,
Don_ 

Don.
I don`t think you can compare a disposable car luboil filter with a complex large marine diesel luboil filter. Normally a marine luboil cleaninginstallation have sentrifuges. Such installation add weigth and require space which make it difficult to accommodate in a submarine. When the VIIC/41 was introduced weight become a problem as the increased diving depth required a heavier steel plating and every possible excessive weight had to be removed. The lubeoil sentrifuge and the reversing of the diesel engines were sacrificed and a large sofisticated lubeoilfilter was installed. Such a filter do not have a disposable insert as on the car engines, but are of a "selfcleaning" type, either by means of a reversible oilflow,back wash type, flushing the contaminations to the dirty oil tank or  a "knife filter" which has a long rotary steel knife ( brush) along steel steel filter insert which skims off the contamination dropping it to the bottom of the filter where it is drained to the dirty oil tank. I guess the VIIC had the first type for the lubeoil- and for the fuel the "knife" type filter after the fuelfilters. In your text showing the filters on the front of the engines it seems to me you are mixing up the double fuelfilters with the lubeoil filters. The VIIC lubeoil filters are single,  much larger, some 400 mm diameter and 600mm long,  and not generally visible, placed under the floorplating forward engineroom in the area where the  sentrifuges used to be.
As to the fuelfilters attached on the front , you have a port and starboard fuel knifefilter placed behind the hp fuelinjection pumps as shown on the image below. 
The drawback with lubeoilfilters is watercontamination, quite common on a submarine. You had to rely on a certain settling in the systemtank, however if the lubeoil emulsified you are lost, it happened once in three year with me.
Otherwise I believe the text is OK.
Tore

[tore]

Simon.
I am not sure of you text under blown head gasket and watercontamination. A leakage of water into the lubeoil system is not possible by a "blown gasket" between the cylinder liner and coolingwater system. As you`ll see from my image below, the upper part of the cylinderliner is raised uncooled in the way of the cyliderhead joint with the liner. Yet we had quite often the cylinders filled with seawater which in some rare cases caused emulsificaton of the lubeoil. The main reason for the waterintrusion was a leaking main hull exhaustvalve. These valves although equipped with a pneumatic grinding machine had a tendency to leak, some times filling the exhaust manifold and the cylinders with seawater submerged. As previously told, our starting routine was always to blow through the engine with the indicatorcocks open to blow out the water prior to starting, to prevent waterstroke. We even did that after diving to prevent water accumulating just after the dive, however as this increased the internal pressure in the boat we had to restrict such procedure. Yet seawater contaminations happened by leakages through the pistonrings down to the luboil systemtanks.
Tore

[Don Prince]

Hello Mr. Tore,


The 'Blown Head Gasket" was my post...


Regards,
Don_

[NZSnowman]

Vent valve for MB & RFO 2 Tank (Stb)


Fig. 1. Vent valve for MB & RFO 2 Tank.


Fig. 2. Vent valve for MB & RFO 2 Tank.


Fig. 3. Under deck view of the vent valve for MB & RFO 2 Tank.


Fig. 4. Deck view of the collection for the valve for MB & RFO 2 Tank.
This images has been resized. Click to view original image.

[tore]

Simon.
I guess the gatevalves are ok, but may be you should make som strengthening ribs on the valve casing and a bit heavier stuffing Box, see my image below.
Tore

[tore]

Simon.
As far as I remember the gatevalves did not have valve spindle extensions to the casingdeck. Wooden  deckhatches would be more appropriate. Particularerly for the isolating gatevalves, as at sea the casingdeck was awashed  all the time, operating the valves was difficult.  Hence a conversion to the fuel storage mode was usually done alongside in harbour.
Tore

[karel]

@Simon.


To answer your previous question. We currently have a command room in our build and it's triangle count is at 1.6 million. But it will quickly add up since in VR you need to render for both eyes. So 3.2 million for command room. Adding to some custom texture compression techniques that needs an extra geometry pass and the triangle count goes around 5 million. We are baking all our lighting but if we used realtime lights with realtime shadows then the triangle count for one room would easily reach over 10 million. But we are not going to use realtime lights. Also added minimal visual effects like bloom and slight color correction (https://www.dropbox.com/s/03y2dw06ry6hn8j/Screenshot%202016-12-30%2018.27.54.png?dl=0  <-- here is me trying to achieve Das Boot film LUT) and the pixel fill gets more expensive.


Then there are PBR materials, every material has a separate texture for albedo, specular, roughness, normal, ao, metallness and they all need to be as high as possible since you don't want visuals break down when inspecting object up close. Final touch is using 4xMSAA to get rid of all the pesky geometry alias and rendering this all becomes quite challenging. We need to keep it at 90 frames per second.  Luckily current generation GPU-s can chew trough triangle count pretty easily but trying to add this other stuff and the bottle neck will be quick to come.


That's the biggest challenge, how to balance this all that it would still look and run good.

[tore]

Karel.
I have of course no idea about creating a submarine game,but could`t resist to compare the Das boat scene, which I assume indicates das boot is under attack, with a journalists photo of me on KNM Kaura ex. U 995 demonstrating a submerged dummy attack. I guess the photo is pretty close to the area shown in the moviescene. Note the periscope on my photo is of the original type not the type fitted on present days U 995.
Tore

[NZSnowman]

Simon.
As far as I remember the gatevalves did not have valve spindle extensions to the casingdeck. Wooden  deckhatches would be more appropriate. Particularerly for the isolating gatevalves, as at sea the casingdeck was awashed  all the time, operating the valves was difficult.  Hence a conversion to the fuel storage mode was usually done alongside in harbour.
Tore

Tore, you are correct.
 
While researching the deck of the late war Type VIIC’s. I did noted that the German's had replaced these two small metal hatches, with wooden hatches on the late war Type VIIC’s.

[NZSnowman]

Simon.
As far as I remember the gatevalves did not have valve spindle extensions to the casingdeck. Wooden  deckhatches would be more appropriate. Particularerly for the isolating gatevalves, as at sea the casingdeck was awashed  all the time, operating the valves was difficult.  Hence a conversion to the fuel storage mode was usually done alongside in harbour.
Tore

Tore, you are correct.
 
While researching the deck of the late war Type VIIC’s. I did noted that the German's had replaced these two small metal hatches, with wooden hatches on the late war Type VIIC’s.

Tore, I was thinking about this hatch last night.
 
I am starting to think that they used this metal hatch throughout the whole war. We must remember that this section of the deck on KNM Kaur was rebuild, and I found this metal hatch on U-826 that was launched March 1944. It thinks I can see this metal hatch also on very late war U-boat like U-1305 & 1306, but the photo are very poor and impossible to be 100% sure.

[Don Prince]

Hello Mr. Tore and Maciek,


While reviewing the German Diving Regulation Manual I found the following in Section I, Page 5:


"When orders concerning the operation of shut off valves are given only the words "open" and "close" are to be used.  In feedback about the position of the valve only the words "on" and "off" are to be used.  Words such as "shut, tight and opened", are prohibited"


Is this a translation issue, or is this a German Navy Vs Other World Navies?


Regards,
Don_