1/48 scale Type VIIC U-201 build

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  • Monahan Steam Models
    Captain
    • Apr 2020
    • 755

    #91
    I thought this was kind of neat how it worked out and shows somewhat of a before and after of the stern tube hull modification.

    Click image for larger version

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    Here is the Arkmodel stern tube piece that glues into the back of the hull. I’ve only lightly sanded the I.D. to make it a consistent .500” diameter from end to end.

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    The cutter I made to modify the hull fits nicely into it.

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    Here is how the original Arkmodel part lays in the hull with the stern tube assembly in place.

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    Another view from the outside. The original part still fits the hull like it did before the modification. This photo also provides a before and after visual of what material was removed from the hull. Time to cut and remove the wall of the original part!

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    Kind of cool how that worked out huh? The original Arkmodel part will still need to be modified to allow the muzzle door to swing open but I think I will end up using most of the original part to complete this area of the hull later.

    Nick

    Comment

    • redboat219
      Admiral
      • Dec 2008
      • 2735

      #92
      Originally posted by Monahan Steam Models

      Click image for larger version  Name:	4D1DE6A2-CDB6-4409-85CC-C7356D96A595.jpeg Views:	0 Size:	63.8 KB ID:	156767
      Pumpjet outlet.

      Weird, right?
      Last edited by redboat219; 12-11-2021, 10:24 PM.
      Make it simple, make strong, make it work!

      Comment

      • Monahan Steam Models
        Captain
        • Apr 2020
        • 755

        #93
        Originally posted by redboat219

        Pumpjet outlet.

        Weird, right?
        'Whatcha talkin bout Willis,' tagline taken from Different Strokes by Garry Coleman AKA Arnold.

        Comment

        • redboat219
          Admiral
          • Dec 2008
          • 2735

          #94
          Weird idea about making the aft torpedo tube an outlet for a pumpjet ( inside the hull) in lieu of the props. Steering / pitch control with usual rudder/dive planes.
          Last edited by redboat219; 12-12-2021, 11:55 PM.
          Make it simple, make strong, make it work!

          Comment

          • Monahan Steam Models
            Captain
            • Apr 2020
            • 755

            #95
            Finally got around to working on the stern plane linkage today. The piece of material that I was searching for locally a week ago to make the original stern plane shaft mechanism that I had wanted to make was ordered and should be here this week. That design will allow the shafts and lever arm to be removed from the hull after the hull halves have been bonded together. For now I’m using the compromised design that I came up with a week or so ago.

            The rest of the linkage stays the same.

            Click image for larger version

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            Here is the main link to the stern plane shaft. The link end at the aft end uses 1/32” brass wire and is the stepped up to 3/32” brass tube before being stepped back down to 1/16” brass rod. This is done to reduce flex in the link.

            Click image for larger version

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            Top view of the main link connecting to the intermediate stern plane lever arm situated between the propeller shafts. From the intermediate lever arm the linkage is connected to the servo link connection arm on the forward end of the stern torpedo tube support. Also visible is the servo link arm connection for the rudder gear.

            Click image for larger version

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            Another view of the same.

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            Now with the stern torpedo tube mounted in place and rudder linkage connected. Still need to connect the rudder and stern plane rods to the servos but that will only take a few minutes. Everything is designed to be removed and easily worked on just as Bob Gato quickly noticed and pointed out earlier in this build thread.

            Besides finishing up on the torpedo launch linkages, the last major mechanical connections that need to be made will be from the motors to the shafts. I have a crazy idea of designing magnetic slip clutches for each motor to shaft connection. This has been done before and is not a novel idea by any stretch. It is an added fail safe not to blow the main system fuse should the props become fouled and motors overloaded. Probably not needed but hey, I got the free time to do what ever the hell I feel like doing.

            Nick

            Attached Files

            Comment

            • reddevil
              Commander
              • Jun 2009
              • 346

              #96
              Good for you. Use your time as you want. Cheers. Amazing build.

              Comment

              • trout
                Admiral
                • Jul 2011
                • 3545

                #97
                Originally posted by Monahan Steam Models
                I have a crazy idea of designing magnetic slip clutches for each motor to shaft connection. This has been done before and is not a novel idea by any stretch. It is an added fail safe not to blow the main system fuse should the props become fouled and motors overloaded. Probably not needed but hey, I got the free time to do what ever the hell I feel like doing.

                Nick
                I am playing with this too! I can do flat surface to flat surface, but been playing with simple notches to give better grip and to push through small weed issues. Magnets slide off each other pretty easily. I can add more magnets or go bigger, but might create an alternate universe and distort time and space. Look forward to what you discover as well. I could also slightly angle the magnets to improve gription (grip and traction).

                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

                • gantu
                  Commander
                  • Apr 2009
                  • 360

                  #98


                  Regards Gantu

                  Comment

                  • Monahan Steam Models
                    Captain
                    • Apr 2020
                    • 755

                    #99
                    Originally posted by trout
                    I am playing with this too! I can do flat surface to flat surface, but been playing with simple notches to give better grip and to push through small weed issues. Magnets slide off each other pretty easily. I can add more magnets or go bigger, but might create an alternate universe and distort time and space. Look forward to what you discover as well. I could also slightly angle the magnets to improve gription (grip and traction).
                    That’s awesome Tom! I will definitely share what I find.

                    What I can see being some initial design objectives would be the gription as you point out would need to easily overcome any parasitic drag in the shaft and bearings as well as normal operating conditions. The magnetic coupling must slip before the peak amperage draw from the motor becomes higher than whatever is determined to be the ideal threshold limit. With a twin motor twin speed control the combined peak amperage draw from both before magnetic slippage occurs would need to be lower than the main fuse.



                    Comment

                    • Monahan Steam Models
                      Captain
                      • Apr 2020
                      • 755

                      Originally posted by gantu

                      Gantu,

                      Great photos! Thanks!

                      Nick

                      Comment

                      • rwtdiver
                        Vice Admiral
                        • Feb 2019
                        • 1768

                        Originally posted by Monahan Steam Models
                        Finally got around to working on the stern plane linkage today. The piece of material that I was searching for locally a week ago to make the original stern plane shaft mechanism that I had wanted to make was ordered and should be here this week. That design will allow the shafts and lever arm to be removed from the hull after the hull halves have been bonded together. For now I’m using the compromised design that I came up with a week or so ago.

                        The rest of the linkage stays the same.

                        Click image for larger version

Name:	5B446B6F-FA38-451F-9715-0B63BDCE5684.jpeg
Views:	311
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ID:	156830

                        Here is the main link to the stern plane shaft. The link end at the aft end uses 1/32” brass wire and is the stepped up to 3/32” brass tube before being stepped back down to 1/16” brass rod. This is done to reduce flex in the link.

                        Click image for larger version

Name:	1606AC9E-BA77-4D8A-8805-8F86ED52190C.jpeg
Views:	263
Size:	69.5 KB
ID:	156834

                        Top view of the main link connecting to the intermediate stern plane lever arm situated between the propeller shafts. From the intermediate lever arm the linkage is connected to the servo link connection arm on the forward end of the stern torpedo tube support. Also visible is the servo link arm connection for the rudder gear.

                        Click image for larger version

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ID:	156832

                        Another view of the same.

                        Click image for larger version

Name:	976EB379-8884-46CD-850B-1477D8265F41.jpeg
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ID:	156833

                        Now with the stern torpedo tube mounted in place and rudder linkage connected. Still need to connect the rudder and stern plane rods to the servos but that will only take a few minutes. Everything is designed to be removed and easily worked on just as Bob Gato quickly noticed and pointed out earlier in this build thread.

                        Besides finishing up on the torpedo launch linkages, the last major mechanical connections that need to be made will be from the motors to the shafts. I have a crazy idea of designing magnetic slip clutches for each motor to shaft connection. This has been done before and is not a novel idea by any stretch. It is an added fail safe not to blow the main system fuse should the props become fouled and motors overloaded. Probably not needed but hey, I got the free time to do what ever the hell I feel like doing.

                        Nick
                        I love your attitude, Nick.

                        You are a master builder as well! Target boats, Tug boats, STEAM ENGINES, and Submarines. A very skilled craftsman for sure!

                        Rob
                        "Firemen can stand the heat"

                        Comment

                        • Monahan Steam Models
                          Captain
                          • Apr 2020
                          • 755

                          Originally posted by rwtdiver

                          I love your attitude, Nick.

                          You are a master builder as well! Target boats, Tug boats, STEAM ENGINES, and Submarines. A very skilled craftsman for sure!

                          Rob
                          "Firemen can stand the heat"
                          Thanks Rob! I just like building stuff and there’s so many different types of neat things to make and ways of making them.

                          Comment

                          • Monahan Steam Models
                            Captain
                            • Apr 2020
                            • 755

                            Spent most of the day with out power to the house. We’re in the middle of adding more solar panels to the already massive system we have currently. We’re rated as a small power plant for the local grid. In addition to the panels we added to the system today we also added a bank of Tesla power wall batteries and brought in a crane this morning to set the back up generator on its concrete pad. Lots of redundancy.

                            The shop however is on a separate 3 phase electrical system so I spent part of the day in there enjoying not being back in the Stone Age.

                            I finally was able to get a piece of the material that I was looking for last week to create the stern plane shaft system that I had originally had in mind for this build. It’s a piece of 3/32” X .014” wall square brass tube. Nothing special to get unless you live in the sticks!

                            Anyways here’s the original stern plane design that is completely removable from a bonded together hull.

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                            Here’s the finished parts that make up the assembly. The center link arm has a square hole that accepts a short length of 3/32” square tube to be freely slide through it. This allows the center link arm to be dropped down into the narrow hull space where the assembly lives.

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                            3/32” tube slide into center link arm

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                            Each dive plane has a square drive socket and round bearing surface to mate up to the bearing in the hull add square drive shaft from the center link.

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                            Stern planes rough assembled on internal shafts.

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                            Everything connected together. A partially threaded pin with 1/16” od shaft will provide the outer most plane support through the molded abs stern plane guards. This will also keep each stern plane in place.

                            Nick

                            Comment

                            • Monahan Steam Models
                              Captain
                              • Apr 2020
                              • 755

                              Started work on the magnetic shaft couplers today. I have to say spinning them by hand and hearing the click click click of the magnets slipping and grabbing again is somewhat therapeutic in a strange satisfying way. We’ll see if it’s still therapeutic in normal operating conditions.

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                              The side of the coupler that is fixed to motor has four 1/8” dia. X 1/4” length magnets embedded into the mating face of it with all magnetic poles facing the same direction. The center of the coupler supports two stainless steel sealed ball bearings. (Had them on hand, may switch to ceramic ball bearings later)

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                              The output shaft side of the coupler also has the same four embedded magnets with opposite facing poles than the motor side coupler. A 4mm center shaft engages with the bearings in the motor side coupler to keep everything supported on the shaft axis and rotating freely during slippage.

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                              The two parts of the magnetic shaft coupler snapped together.

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                              Sneak peak of the motor module installed with one of the magnetic couplers in the hull and connected to the port side shaft. The double universal joint has a bit more of a offset than what I would prefer to see but the assembled components rotation by hand is still very smooth.


                              Comment

                              • redboat219
                                Admiral
                                • Dec 2008
                                • 2735

                                Nick,
                                would offsetting the shaft of the magnetic coupler to one side work, something like on a countergear? M is the motor P is the propeller, instead of intermeshing teeth you use magnets.
                                .
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                                Make it simple, make strong, make it work!

                                Comment

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