Tores mailbox VIIC and VIIC/41 operation and technical details

[Don Prince]

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]

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

[tore]

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]

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]

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]

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]

Hello Mr. Tore,


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


Regards,
Don_

[tore]

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]

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]

Hello Mr. Tore,


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


Regards,
Don_

[tore]

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]

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

[Don Prince]

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]

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]

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