1/48 scale Type VIIC U-201 build

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  • Monahan Steam Models
    Captain
    • Apr 2020
    • 755

    Originally posted by RCJetDude
    Love the innovation Nick! Top notch stuff.
    Thanks Bud!

    I’d say the biggest win so far with the new design was having another crack at correcting the main ballast tank volume and CG placement along with the improved ballast venting and internal stay design on each section. There are other significant wins but those are the ones that make a big difference out of the gate.

    Nick

    Comment

    • MFR1964
      Detail Nut of the First Order
      • Sep 2010
      • 1290

      Nick,

      The Type XXIII has a kind of insert at the radial split, no pins needed, there is only one way to connect, shearforces are limited because of the insert, i use 8 magnets to keep things together, need about 8 kg of pulling straight to make it seperate.
      Opening up happens to break it's back ( shearforce) then you can pull things apart, a pretty easy job, SD is retrieved without using tools, it was all designed no tools needed.
      The Ko-Hyoteki was a difffent story, made the model myself, so had to figure out the pins and magnets, same force needed to open things up, yet again no tools needed, the SD is removed with some more effort due to the design, all connections on both are either magnets or lipseals.

      Manfred.
      I went underground

      Comment

      • Monahan Steam Models
        Captain
        • Apr 2020
        • 755

        With the new sectional version of the WTC no longer having the wire pass through conduits in the central ballast tank between dry compartments, I needed to shift focus to designing a new “in the wet” wiring harness that would be water tight. I don’t like exposing conductors to chances of corrosion. What I am going for with the new wiring harness is a design that stays in place in the hull the majority of the time. As the build progresses this will hopefully make more sense with the way this boat is being built.

        The original WTC had two conduits that passed through the ballast tank. One for the eight data or signal wires and the other for the 12v, 5v and ground power cables.

        The toughest or tightest area to try to pass all these connections through is the aft end cap area. There is not a lot of room available between the aft WTC end cap and the motor/servo module that is mounted in the hull.

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        This is the area I’m referring to.

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        A better view with aft end cap removed.

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        With the original WTC design, I had already worked out the water proof twin pair of 3 conductor brushless motor bulkhead connections. To get power and signal to the rudder and stern plane servos I worked out using this water proof 4 pin connector in the center. Pins were for positive, negative and a pin each for the signals.

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        A view of the backside of the original WTC aft end cap. Life was all figured out at this point… Time to mess all that up!

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        Now that I needed more than just the four original pins to pass through the aft end cap, I swapped the connector out for this 17 pin version. This will handle the four original pins needed for the rudder and stern plane servos as well as the eight data signals needed for the forward compartment and five additional pins of which four will be used for communication with the Arduino unit while the WTC is sealed up. (Didn’t have that before. Will come in handy later)

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        View of the new 17 pin connector from the other side of the end cap.

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        I needed to come up with a compact water proof harness connection to fit into the tight space that was available in the aft area for all these new wires and still have easy connections for the aft servos. This is what I designed. It looks like the Munsters drag car coffin. The six 2mm bullet connections are for the two aft servos. Silicon tube will be slid over them to seal out the water.

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        I built a strain relief into the new connector housing for the main data cable.


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        Once I solder the connections for the six gold bullet pins this void area will be filled with potting resin to seal the harness and housing from water.

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        Here’s how it click connects onto the bulkhead connection.

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        Fits down in there pretty good.

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        With the brushless motor connections made up.

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        Top view down through the aft piston trim tank.

        This was the worst of the figuring out that needed to be done for the harness design and packaging for the new WTC version and so far so good. The design allows the aft section of the WTC to slide back a quarter of an inch from the ballast and forward sections, disengaging it to be removed and the connections to be quickly unplugged without removing everything else.

        Nick
        Attached Files

        Comment

        • neitosub
          Lieutenant Commander
          • Nov 2021
          • 129

          That’s a really sleek connector Nick, love the fact that you even printed in the positive and negative terminal markings! How did you waterproof the rear control surface servos? From what I see they look like the standard “Tower Pro 9G” servos. Is the servo compartment filled with silicone with an O-ring seal below the servo horn?

          Nate

          Comment

          • Monahan Steam Models
            Captain
            • Apr 2020
            • 755

            Thanks Nate,

            It took a bit of head scratching before I came up with what you see. The terminals are marked positive, negative and signal but the squiggly line for signal didn’t turn out so good. Looks almost like the negative symbol LOL.

            The servos in the photos are stock and are not water proofed yet. Just haven’t gotten around to that yet. Will probably water proof all the servos and a few extra replacements at the same time. I plan to fill them with either mineral oil or CorrosionX. Then I’ll dip them a few times in Flex seal up to the bottoms of the mounting tabs. I may or may not use a O-ring underneath the servo horn and some silicon sealant for the servo horn screw if it is not a blind hole.

            Nick

            Comment

            • neitosub
              Lieutenant Commander
              • Nov 2021
              • 129

              Cool stuff! From what I remember the servo horn screw hole is a blind hole, but this might vary depending on the version of the servo, I’ve seen so many rebrandings of these blue micro servos ;)

              Comment

              • Monahan Steam Models
                Captain
                • Apr 2020
                • 755

                Yes there have been a lot of rebranding of these servos with subtle differences. One big difference is where the wires exit the case. Some exit the side and some exit the bottom. I have examples of both of these.

                Comment

                • Monahan Steam Models
                  Captain
                  • Apr 2020
                  • 755

                  Quick build update.

                  Work has been progressing on the design and build of the new water proof data and power cable harness. Last I recall there was something like 48+ wire connections that needed to be made and sealed up.

                  I turned my focus over to the forward end of the hull to work on a mount for the bow plane servo and other parts.

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                  The way I designed the original WTC was to be inserted into the hull through a vertical split separation of the aft hull section. Because of this all the equipment that lived outside of the WTC had to be attached to the forward end cap shown above. The servos for the ballast control and bow planes were inside the WTC and these fancy linkages made everything work outside the WTC.

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                  Another view of the original forward equipment.

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                  Here’s the new forward mount for the bow plane servo and pressure regulator for the torpedoes.

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                  The new equipment mount has two stainless steel alignment dowels that interface with sockets in the forward end cap.

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                  These are the two brass sockets in the forward end cap that mate with the stainless dowel pins.



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                  Here’s forward end of the new sectional WTC inserted into the hull and mated with the dowel pins. This simple connection does a number of things. It locks the forward end of the cylinder at a vertical height in the hull while also keeping it from rotating on its axis. The forward section of the hull does not feature a cradle molded into the hull from the factory to support the cylinder so this takes care of that. Due to the way I split the hull at the waterline, the hull relaxed in a spread apart manner. These pins when mated to the cylinder also pull the two hull halves back together where they originally were. The last jobs the alignment pins perform is keeping the cylinder and forward mount in perfect alignment with each other which later in the build, I will show how this helps with the new data cable connection and how it works with only removing the aft section of the WTC.

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                  The new forward mount was designed to use the existing molded in features of the hull. The stainless steel fasteners I use through out this build are the thread forming type and not the thread cutting type. This reduces the threads in the plastic from becoming worn out quickly if at all.

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                  Starting to populate the forward mount with the gear.

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                  The torpedo launch solenoid pressure regulator installed and the bow plane servo installed.

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                  The forward mount reinstalled into the hull with the bow plane pushrod. Still need to make up the connection between the servo and the pushrod but this is where I got with the build as of today.

                  Going to jump back over to the external water proof wiring harness part of the build. There is some cool stuff with that part of the build that I will hopefully be able to share next. Once all this mechanical and technical part of the build gets done I can hopefully move on to assembling the dang kit! It’s gotta run good before it looks good.

                  Nick

                  Attached Files

                  Comment

                  • SubDude
                    Captain
                    • Dec 2019
                    • 803

                    Dang, you do nice clean work Nick!

                    Comment

                    • rwtdiver
                      Vice Admiral
                      • Feb 2019
                      • 1768

                      Hi Nick,

                      Well, I just purchased the Arkmodel Vll kit and 80 mm WTC from Bob! As you know if you were following the Kilo build that I started, it did not work out for me for many health and shop related issues. I just wanted to say this on Bob's behalf. What an honest and extremely fair man he is! He did give me a (MORE THAN FAIR) partial refund on the Kelo kit towards the Arkmodel system. I am sure that anyone on this forum that has ever had any dealings with Bob knows what kind of person he is as well!

                      I am going to go over your build and pick up on every little morsal of information I can use towards my build. I am sure my build will not even come anywhere close to what you are doing here on this build blog! Thanks for sharing your build!

                      Rob
                      "Firemen can stand the heat"

                      Comment

                      • Monahan Steam Models
                        Captain
                        • Apr 2020
                        • 755

                        Thank you Steve!

                        Rob,

                        The Arkmodel type VII is a great model. You’ll enjoy building it. The 80mm cylinder from Bob will be perfect for this boat and the top of the cylinder will be just at water line or slightly below depending on how you mount it in the hull. I’m using a 90mm in my build like the kit was designed for which sits in the hull’s molded in cradles, but this puts the top of the cylinder slightly above waterline which starts to work against you. It’s not much of a problem in my build because I have extra trimming capacity from the forward and aft piston tanks that sit below waterline.

                        If you have any questions during your build, please ask away, I or others who have or who are currently building this model will be glad to help. I went a bit overboard with the way that I chose to build my boat but that is just how I decided early on to build this particular project.

                        Nick

                        Comment

                        • Monahan Steam Models
                          Captain
                          • Apr 2020
                          • 755

                          Started work on the forward data cable water proof connection this morning. Didn’t get very far as the day took a sudden dramatic turn early on but here’s what was accomplished.

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                          These are 17 pin IP68 rated connections that I use at both the forward and aft WTC sections. The connection itself is water and pressure tight but where the cable sheathing enters the molded plastic connection housing, I’ve found is not water tight. So let’s perform some surgery.

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                          This first starts out as carefully sawing into the plastic connection housing just deep enough around it’s circumference where it meets the flexible cable sheathing.

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                          Once the cut is done, the cut off portion of the plastic housing is slide back and removed.

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                          Here’s the connection with the cut off plastic housing portion removed. The next step is carefully cutting away a section of the cables sheathing.

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                          Here I have carefully removed about an inch and a half of the 17 wire cable’s sheathing.

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                          The cable ends are then fed through the forward junction housing for water proof harness. Six of the seventeen data wires are cut from the cable pack which will be connected to a ten pin male connection at the forward end of this junction. This will provide one common five pin connection and five separate connections for the five torpedo solenoids.

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                          Another look at the cable junction assembly. Those loose wires will be connected to a ten pin connector yet to be shown. The whole housing and assembly will be potted in epoxy to water proof it.

                          Nick

                          Comment

                          • rwtdiver
                            Vice Admiral
                            • Feb 2019
                            • 1768

                            Originally posted by Monahan Steam Models
                            Thank you Steve!

                            Rob,

                            The Arkmodel type VII is a great model. You’ll enjoy building it. The 80mm cylinder from Bob will be perfect for this boat and the top of the cylinder will be just at water line or slightly below depending on how you mount it in the hull. I’m using a 90mm in my build like the kit was designed for which sits in the hull’s molded in cradles, but this puts the top of the cylinder slightly above waterline which starts to work against you. It’s not much of a problem in my build because I have extra trimming capacity from the forward and aft piston tanks that sit below waterline.

                            If you have any questions during your build, please ask away, I or others who have or who are currently building this model will be glad to help. I went a bit overboard with the way that I chose to build my boat but that is just how I decided early on to build this particular project.

                            Nick
                            Thanks Nick,

                            I am sure I am going to have a lot of questions. I do appreciate your willingness to lend a helping hand!

                            Rob
                            "Firemen can stand the heat"

                            Comment

                            • Monahan Steam Models
                              Captain
                              • Apr 2020
                              • 755

                              This is roughly where I was trying to get to yesterday with the work being done on the forward data cable connection.

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                              The gold plated 10 pin header is soldered to a printed circuit board and the 6 wires are connected. I chose to use a gold plated pin header for the excellent corrosion resistance properties. The majority of the time, these pins will see no current flowing through them and when they do it will only be for a second or two.

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                              View of the connections to the board.

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                              This header pin retainer keeps everything positioned in correct place until the cavity is filled to the top with the epoxy potting compound. The 2mm stainless screw holding the retainer in place is counter sunk below the housing’s edge, so it will also be no longer visible once the potting compound is poured into the cavity.

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                              Before the potting compound is poured, all connections will be tested one last time to make sure there are no issues before everything is permanently entombed in epoxy.

                              That’s about all for now.

                              Nick

                              Comment

                              • Monahan Steam Models
                                Captain
                                • Apr 2020
                                • 755

                                It looks like the Flying Spaghetti Monster currently but I’m just starting to transfer the guts from the forward dry section over to the new WTC.

                                Attached Files

                                Comment

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