Tores mailbox VIIC and VIIC/41 operation and technical details

[tore]

Don.
Some how I have trouble to post my mail, I`ll revert as soon as it is fixed.
Tore

[Don Prince]

Hello Mr. Tore,


Just an Idea...  After reading the U-570 Report several times; here is my idea...


1. It works OK in the Fuel Oil Configuration.
2. In the ballast Configuration the selector valve is open to the sea.  The valve is above sea level so the sea water only comes up to the sea level in the pipe in this mode.  When the U-Boat is submerged, the expansion tank is equalized through the open selector valve...


Regards,
Don_

[Don Prince]

Hello Mr. Tore,


This is the full detail drawing...


Regards,
Don_

[Don Prince]

Hello Mr. Tore,


additional drawing...

[Don Prince]

Hello Mr. Tore,


When the ballast tanks are in the fuel oil configuration, would they open the residual valves for FBT2 to allow the pipe between the shut gate valves to flood?


Regards,
Don_

[tore]

Don.
I am happy being back.I am not sure I understand you idea 3 correctly. If you have an arrangement as on your sketch in ballast configuration having the ordinary double seated selector valve shut to the headertank and open to an outlet under the casing deck you are venting the tanks if the Kingstons are open. which means you are loosing almost 50M3 buoyancy and do not have sufficient surface draft. I agree you are in conformity with the text and documentation, but unfortunately with a lousy draft. Normally when you are operating an active submarine at sea you`ll have the Kingstons open and ready to dive.   The only time this would work is if the Kingston are shut thus the documentation should have mention these restrictions to my opinion. We have then to assume a remark to the design : the selectorvalve in ballastcondition can be open to the sea only when the Kingstons are shut thus acting as a safety/relief connection to the sea. I am still in doubt if that is the correct arangement.
Tore

[tore]

Hello Mr. Tore,


When the ballast tanks are in the fuel oil configuration, would they open the residual valves for FBT2 to allow the pipe between the shut gate valves to flood?


Regards,
Don_

Don.
The residue venting of fuel/ ballasttanks 2 have  gatevalves pretty close to the ventpipe outlet from the tank. I assume these valves are shut in fuel configuration.
Tore

[Don Prince]

Hello Mr. Tore,


Referring to the attached drawing...


1. In order to establish the final air pressure inside the saddle tanks while on the surface; The diesel exhaust blowing pressure is 0.5 atmospheres above atmospheric pressure of 1.0 atu. Therefore, the saddle tank internal air pressure will be 1.5 atu after the exhaust blowing.


2. The water level inside the saddle tanks will be just above the top of the Kingston ports; the saddle tank's Kingston valves are open to the sea while the U-Boat is on the surface or submerged (water ballast configuration).


3. The air in the saddle tanks will remain captured in the saddle tanks until the vent valves located at the top of the saddle tanks are opened, then and only then will water level rise inside the saddle tanks while the U-Boat is on the surface.


4. It is established that the compensating water outlet pipe is positioned near the very bottom of the saddle tank and well below the standing water level inside the saddle tank. So, there is no means for the ballast tank air to escape from the saddle tank unless the saddle tank is vented.


5. If we compare the water pressure from the surface to the water level at the bottom of the saddle tank where the Kingstons are open to the sea, and then to a point outside the ballast tank at the same water level; the water pressure would be exactly the same.


6. Therefore, the water level inside the compensation pipe going to the selector valve which is open to the atmosphere would be at the sea level.  This would be the water line established by the U-Boat's buoyancy (displacement) Vs the weight of the U-Boat.


This would be the same principle with the following test; if we took a water glass and drilled a hole through the bottom center and placed a straw through the hole until it lined up with the top edge of the glass, then we turn the water glass upside down and partially submerge it into a bath tub filled with water. The air in the glass would be slightly compressed as we forced the glass into the water, and the water level in the straw would match the water level in the bath tub. If we had a means of balancing the glass, then it's weight would establish the water line for the glass in the tub...


What do you think?


Kind regards,
Don_

[tore]

Don.
When the ballasttank is open to the sea, the seawaterlevel rises in the tank until the counterpressure of the air/exhaustgas is equal to that of the seapressure. When the system is in ballance,  the pressure is the buoyancy pressure. When the ordinary vents are opened, the pressure is released and air /exhaustgas escapes from the ballasttank, allowing the seawater filling the tank.
When the selector valve outlet is open to the air as in the proposed system, the deplacement pressure is released as for normal venting. The only difference is, as the pipe for the selector valve  ends in the tank residue water this water shall be forced out thru the selectorvalve outlet in stead of air/exhaustgas, followed by the seawater thru the Kingstons. When the water enters the tank it compresses  the air/gas on the top leaving a small volume air/ exhaustgas in the top of the tank having the ambient seapressure when the system is in ballance. This means that when you release the deplacement pressure in the ballasttank thru the selectorvalve with open kingstons, seawater is filling the tank and you loose you deplacement buoyancy. According to Archimedes you are sinking with a small volume of air/ gas compressed on the tanktop.  The only way to avoid this is to shut your kingstons which is not wise for an operational submarine.
Tore

[Don Prince]

Hello Mr. Tor,


If the expansion pipe outlet is below the water line in the saddle tank, the how can the tank vent through the selector valve to the atmosphere? There is NO path to vent the ballast tank???

[Don Prince]

Just like the Glass in the bath tub...  the air pressure in the glass has not escaped, so the water pressure will force the water up the straw until it matches the tub level...

[Don Prince]

"When the selector valve outlet is open to the air as in the proposed system, the displacement pressure is released as for normal venting."

(1) The water from the sea through the open Kingstons goes up the pipe to sea level. The ambient pressure inside the saddle tank maintains the current water level in the ballast tank as set by the displacement Vs the weight of the U-Boat.


If the Kingstons were shut, then I would agree that the 1.5 Atu ambien air pressure would push the water up the pipe if the water column weight were less than the upward pressure differential.  However, in this instance the ballast tank is being vented, but the U-Boat still maintains the same water line because we have not changed displacement with the shut Kingstons.

[Don Prince]

Hello Mr. Tor,


Would you please review the modified reply #3356


I'm staying up to work with you on this subject...


Kind regards,
Don_

[Don Prince]

Hello Mr. Tore,


Just for conversation...  Lets say we closer the selector valve.  Then we got a hose with a shut-off valve at one end, and place it at the deck height.


1. We then have a diver to take the other end of the hose down to the level of the internal compensating outlet pipe height. However, several feet away from the Kingston open port outside the U-Boat saddle tank.  then we open the hose valve. I believe the water will be forced up the hose to sea level. correct?


2. Now, we have the diver to take the hose right up next to the Kingston open port outside the U-Boat at the same height and perform the exact same experiment.  The results should be exactly the same. correct?


3. Finally, we have the diver to place the hose inside the ballast tank, and place it next to the compensating valve outlet. Then we open the hose valve and vent.  I believe the external water pressure will push the water up to sea level and stop, just like the other experiments.  The internal saddle tank air pressure of 1.5 atu has established the water level inside the saddle tank.  The venting hose is filled with water from below the saddle tanks internal water line, and that water came from the sea.


Where am I wrong with this logic?


Kind regards,
Don_

[tore]

Don.
1. When the selectorvalve is open to the air (sea) the seawater enters the saddletank thru the kingstons as the displacement pressure is released, the tank is no longer a buoyancy tank as no  counterpressure prevents the water to enter, if you put the selector outlet pipe down into the sea at the level of the kingstons you`ll have a counterpressure equal to the inletpressure and the system shall stabilize keeping the deplacementpressure and no air/ exhaustgas shall escape.
2 You assumption with shut Kingstons is correct appart from the 1,5 atu. The displacement pressure in the saddle tank would probably be less as the Kingston are about 2,2 meters below the sealevel at normal draft. The 1,5 atu is the limit for the exhaustgaspressure and relates to the mainengines backpressure limit rather than the saddletank deplacement pressure.
Tore