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1/48 scale Type VIIC U-201 build

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  • Nick,

    I was curious how much my deck weights, 1184 grams, total weight of the boat 17000 grams, did some calculations and ended up with 7% of the weight, that 2% is much to low, my mistake, that launching from one channel, arduino?

    Manfred.

    I went underground

    Comment


    • Manfred,

      After reading your last post, I decided to borrow the Mrs. kitchen scale again to get some weights on this boat. The above waterline deck weighed 504 grams and the rest of the boat below waterline weighs currently 3910 grams so total weight 4,414 grams. So about 11.5% of the weight above waterline.

      Some other figures for the fun of it. The WTC displaces 3,112 grams of water when the main ballast tank and trim tanks are empty.

      The WTC weighs 2,134 grams. Main ballast tank holds 631 ml of water and each of the two piston trim tanks holds 100 ml of water.

      The main ballast tank is definitely oversized and I am considering currently making a newer version of the WTC that will be 3 separate modules instead of one as it is currently. The overall project has evolved since I first started it. The big difference being the waterline cut. The current WTC was designed to be removed with a vertically split hull at the aft section, so a lot of the necessary controls, equipment and connections were incorporated into the design.

      The waterline cut makes removing the current WTC very easy but what I am asking myself now is why bother removing the whole thing and disconnecting all the plugs and plumbing connections ever time? The main ballast tank can be one of the three new modules the should not need to be removed other than for servicing. The forward section of the WTC that currently holds all the pumps, torpedo launching electronics, sensors and other equipment with all of their plugs and plumbing also really does not need to be removed as often and can be another separate module.

      The last section of the current WTC being the aft compartment is the power distribution and brains of the system. This is the only section that needs frequent removal to gain access to the batteries. Breaking the WTC up into these 3 separate modules would make it even easier to service the boat it seems.

      As far as launching the torpedoes from one channel, I am using a device Kevin McLeod of KMC electronics designed called a TCP or torpedo controller pneumatic. It allows you to individually fire up to six bow torpedoes and four aft torpedoes with the use of a 3 position switch. The switch is normally kept in the center position which is also the launch position. Moving the switch either direction from center arms a forward or aft torpedo tube. After holding the switch in that position for one second, the switch is returned to center and launches that tube.

      I found that it can be a bit tricky getting the exact sequence of timing correct for moving the switch to fire a tube so I wrote a sub program for the Arduino to use the same switch movement but have the program take care of the rest. Meaning if I move the switch on the remote either direction from center, I can hold it there for any amount of time but when I move the switch back to center the program kicks in and handles the timing and sends appropriate command to the TCP that it is looking for.


      Nick

      Comment


      • U-201’s main ballast tank is getting a major rework.

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        • First part for the new ballast tank.

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          • Made some progress today on the new main ballast tank for this build.

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            The business end that houses the servo to control the main tank vent and emergency blow valve, along with the fittings for the LPB snort connection and LPB outlet nipple.

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            Still more work to do to finish it, but the cam that moves the main vent valve can be seen here on the opposite side of the aft ballast tank bulkhead. Using internal stays to keep the forward and aft ballast tank bulkheads from pushing apart. Outer cylinder just floats on bulkhead o-ring seals. Using super soft durameter 10 silicon for the main ballast tank vent seal.

            Nick

            Comment


            • Originally posted by Monahan Steam Models View Post
              Made some progress today on the new main ballast tank for this build.

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              The business end that houses the servo to control the main tank vent and emergency blow valve, along with the fittings for the LPB snort connection and LPB outlet nipple.

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              Still more work to do to finish it, but the cam that moves the main vent valve can be seen here on the opposite side of the aft ballast tank bulkhead. Using internal stays to keep the forward and aft ballast tank bulkheads from pushing apart. Outer cylinder just floats on bulkhead o-ring seals. Using super soft durameter 10 silicon for the main ballast tank vent seal.

              Nick
              Nick, are those magnets in the bulkhead below your thumb?

              Comment


              • Originally posted by RCJetDude View Post

                Nick, are those magnets in the bulkhead below your thumb?
                Steve, good eye!

                Yes those are magnets. At either end of the ballast tank, each bulkhead will have four magnets each and four stainless steel 1/8” alignment dowel pins. The end caps or bulkheads on the forward and aft WTC sections will also have four magnets and four dowel pin sockets to mate up to either end of the central ballast tank. This way the three main sections of the new version of the WTC can click together as if it was still one length of tube.

                This version of the WTC keeps almost all of the original design work and component layout of the original WTC and is also identical in length. Besides being broken up into three separate modules, the only other changes made to the design was removing the bow plane and ballast control servos in the forward section. The upper and lower equipment shelves for both the forward and aft sections now also bolt to the new bulkheads that mate up to the central ballast tank. The equipment shelves now act as internal stays, keeping the end caps from blowing out of the cylinder ends from the piston trim tanks increasing internal pressure during use.

                Also all the junk for the ballast control and dive plane linkage that was hanging off of and just below the forward trim tank is now gone. The ballast control and forward dive plane servos are now in the wet like the rudder and stern plane servos. Doing this eliminated the last two pushrod seals.

                Nick

                Comment


                • Here’s the finished dry mocked up main central ballast tank for the U-201 project. This is the first of three new modules that will make up the WTC.

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                  At either end of the ballast tank are 4 stainless steel alignment dowels and four magnets situated in both bulkheads. The bulkhead for the mating WTC module has four dowel pin sockets and four magnets.

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                  The working guts of the ballast tank are mounted in the Aft bulkhead.

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                  One of the mating bulkheads clicked into place on the aft ballast tank bulkhead. Very solid and secure connection.

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                  Another view of the same. Need to remake the silicon vent valve piece. Although it seals and works well, it looks like crap because I cut it to size in a hurry and did a sloppy job but hey it works great still.

                  Staring work on the forward and aft WTC modules next. Then hopefully back to the main boat build.

                  Nick

                  Comment


                  • I Love it!
                    If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.

                    Comment


                    • Nick.

                      Smart thinking, connecting those WTC elements with pin and magnets, pins will counteract the shear forces and the magnets keep them on their place, pretty much the same as i did with the hull of the Ko-Hyoteki.
                      So, only the electronic unit is the one you want to remove on a regular base?

                      Manfred.
                      I went underground

                      Comment


                      • Manfred,

                        Yes the pin and magnet connections work great for the reasons you point out. I believe your Type XXIII also uses this system for the vertical split?

                        Yes just the aft electronic unit will need to be removed regularly to access the batteries so they can be removed for charging. The aft WTC unit and the forward WTC unit each have a port on them for pressure testing for leaks prior to running and for ventilation during storage.

                        When I did the redesign of the WTC, I shortened the aft end of main ballast tank by almost 32mm. This brings the CG of the ballast tank to be almost exactly centered under the tower. Capacity changed from 631ml to 500ml.

                        Nick

                        Comment


                        • Here is the new sectional version of the WTC. All the major components are now made and dry assembled.

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                          The empty WTC with equipment shelves waiting for components.

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                          The sections separated.

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                          Side by side overall comparison of the original one piece tube WTC next to the new 3 section version.

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                          Overhead view of the forward compartment. Slightly different layout of the components that will populate the upper shelf since the two servos have been removed.

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                          Overhead comparison of the ballast tank sections.

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                          Finally the overhead comparison of the aft sections. The aft equipment shelves are identical between the two designs. No changes we made. Just the rear end cap received some minor design changes and added the forward end cap.

                          The next step will be to transfer all the equipment from the original WTC into the the forward and aft sections of the newer version.

                          Nick

                          Comment


                          • Great looking setup.
                            Of the 40,000 men who served on German submarines, 30,000 never returned.”

                            Comment


                            • Originally posted by Das Boot View Post
                              Great looking setup.
                              Thanks Casey!

                              We’ll soon see if the effort to split up the WTC sections makes much of a difference in the ease of servicing the boat or not. LOL

                              Nick

                              Comment


                              • Love the innovation Nick! Top notch stuff.

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