Tom Chalfant - Bronco Type XXIII

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  • trout
    Admiral
    • Jul 2011
    • 3545

    Tom Chalfant - Bronco Type XXIII

    It is a little early, but as soon as the Skipjack is done I will move onto this one.
    The goal is to have a functioning sub by the end of December. I do not want to rush this so detailing and fun additions may need to come after it runs in the wet.
    We will see!
    If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.
  • trout
    Admiral
    • Jul 2011
    • 3545

    #2
    "In the moment when I truly understand my enemy, understand him well enough to defeat him, then in that very moment I also love him." - Ender's Game
    Studying photos again of the Type XXIII I saw something very interesting. It is the way the sub sits on the surface. Here is how I have seen it set up on some R/C submarines:
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    Now here is how I see it running on the 1:1 version.
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    Do you see the difference? The aft is submerged on the real submarines. Here are more photos.
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    Even the risen U-2365 was operational with a aft end submerged.
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    This next photo is speculation, complete speculation on my part, so with that being emphasized, notice the way it was tied to the crane for lifting. My thinking is that it is balanced between the cables. That in-between the cables would be the center of gravity. Is that a stretch for me to guess that? If not, then the center of gravity might be forward of the conning tower.
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    Anyways, my final point is U-2326 was painted with the operational waterline of aft submerged. This was taken in 1946.
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    Although, at the time of her surrender on May 14, 1945 - her paint scheme looks like it was all black. Oh and her aft is submerged.
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    Trimming the sub this way will be interesting, I have no idea if submerged if the sub ran level - I am assuming it did. So, there might be issues with the leveler trying to raise the aft end while on the surface.
    Last edited by trout; 11-24-2013, 05:08 AM.
    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

    • Subculture
      Admiral
      • Feb 2009
      • 2119

      #3
      This type of trim is common with many spindle stern type boats, where the prop is prone to ventilation when close to the surface. They still do it on modern boats, for instance if you look at some pictures of the Astutue class, you'll see it tends to be trimmed with its bum down in the water.

      I've always thought of the XXIII as a 'big' Seehund. The hull shapes are essentially the same, just that the Seehund has a longer and squatter conning tower. these tended to be trimmed in the same way when you look at pictures of them in their element.

      The stern down trim is achieved by flooding the rear tank a little or perhaps stowage of ballast. In a model with a single tank, you can get the same effect by either biasing the tank a little towards the front, or adding ballast shifting. The former method has the snag that with changing water density so will your longitudinal trim alter.

      The latter is most easily achieved by mounting the battery on a cradle and moving it back and forth with a servo. There are details on this in Norberts book. Lipo batteries don't offer the same mass as other types, so you might have to add lead to create a decent amount of weight, generally 10-20% of the boats overall displacement is adequate to get good control of the boats longitudinal trim.

      Not many sub modellers bother with this detail, but it's not a huge effort to install if you have a spare channel and all I can say is try it, you'll like it.

      Comment

      • Subculture
        Admiral
        • Feb 2009
        • 2119

        #4
        The C.G on the XXIII should be where I've painted in the red line, no more no less. That would be the C.G when the boat is submerged, and the boat should be level. For surface running with the stern down as shown in earlier pictures, the C.G would be aft of this point.

        Comment

        • Albion
          Captain
          • Dec 2008
          • 651

          #5
          Originally posted by Subculture
          This type of trim is common with many spindle stern type boats, where the prop is prone to ventilation when close to the surface. .
          Check out the Type D koryu's, thats why i installed the ballast shifter
          Next time someone points out it takes 42 muscles to frown, point out it will only take 4 muscles to b1tch slap them if they tell you how mnay muscles you need to smile:pop

          Comment

          • Subculture
            Admiral
            • Feb 2009
            • 2119

            #6
            Bear in mind that for a small model like the XXIII a conventional servo has more than sufficient grunt to shift the weight backwards and forwards, and makes installation and control a breeze. Even the small 9 gram servos can move a pound or so of weight fairly easily.

            The little delphin I am working on has a ballast shifter in the outline. I plan to use one of the little 1.5 gram linear servos to push the main battery pack fore and aft.

            Comment

            • He Who Shall Not Be Named
              Moderator
              • Aug 2008
              • 12255

              #7
              Damn good discussions. I'm taking this all in. Great stuff, guys.

              M
              Who is John Galt?

              Comment

              • trout
                Admiral
                • Jul 2011
                • 3545

                #8
                Wow, yeah that is some great input. Andy, you really need to do more videos. I guess I got to open Norbert's book again. It just gives me a headache every time I do.

                Went out and bought a melamine board and began to glue the halves together.
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                The fit was good, but on one set of halves it fit with a wobble in it. Meaning either the bow would go slightly high or slightly low.
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                So I placed the pieces on top of the already glued half and the aft end would not come together. There are some injection tabs left in that needed to be snapped off.
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                With the tabs off, I tacked the pieces together and then set the half down on the board for better application of cohesive glue. After it set up, did a test fit and the halves fit pretty good.
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                Now the decision is how to fit the rudder mechanics and when. Place it in now and seal the halves or put it in later and either open the hatch to allow access or I might be able to feed the rod through the bottom.
                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

                • He Who Shall Not Be Named
                  Moderator
                  • Aug 2008
                  • 12255

                  #9
                  You can fish the rudder pushrod and bell-crank in there with the unit assembled, so go ahead, glue away, Tom

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                  M
                  Last edited by He Who Shall Not Be Named; 11-24-2013, 06:20 PM.
                  Who is John Galt?

                  Comment

                  • trout
                    Admiral
                    • Jul 2011
                    • 3545

                    #10
                    O.K., If I see the photos correctly, there is a hole drilled in the top that you drop the wire (rudder shaft) down through. Do I still need to thin the walls down in the upper rudder support?
                    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

                    • He Who Shall Not Be Named
                      Moderator
                      • Aug 2008
                      • 12255

                      #11
                      Originally posted by trout
                      O.K., If I see the photos correctly, there is a hole drilled in the top that you drop the wire (rudder shaft) down through. Do I still need to thin the walls down in the upper rudder support?
                      Yes on both counts. Grind a 1/8" hole into the top of the upper rudder support -- in alignment with the rudder operating shaft -- and the bottom of the lower rudder support. Drill holes to pass the 1/16" rudder operating shaft into the bottom of the upper rudder support and the top of the lower rudder support.

                      With the hull glued together, to install the rudder:

                      1. pass the rudder operating shaft up through the bottom of the lower rudder support -- place the rudder into position -- and push the operating shaft up into the rudder, through the bottom hole in the upper rudder support and hold it there by tightening the rudder operating shaft set-screw (on the starboard side of the rudder)

                      2. Put a Z-bend into the end of a 12" length of 1/16" diameter brass rod. This will be your rudder pushrod. Make up the Z-bend to the bell crank and slather on some CA to make the two a rigid assembly (don't sweat it, that union will break later). Push the bell crank, using the pushrod as a handle, into the tight confines of the upper rudder support. While doing this look down through the 1/8" hole in the top of the upper rudder support and finagle things till the bore of the rudder pushrod is in alignment with the top of the rudder operating shaft. Push the rudder operating shaft upward, through the bore of the rudder bell-crank.

                      3. tighten the set screw within the rudder bell-crank to make it fast to the rudder operating shaft.

                      4. tighten the set-screw in the side of the rudder to make the rudder fast to its operating shaft.

                      5. sing my praises, sprinkle rose petals at my feet, and deliver 20 Filipino virgins (female types, please) to my bed chambers, immediately!

                      M
                      Who is John Galt?

                      Comment

                      • trout
                        Admiral
                        • Jul 2011
                        • 3545

                        #12
                        David,
                        1.Got it!
                        2. Yep, did that with the Gato
                        3. O.K.
                        4. Makes sense
                        5. I couldn't carry a note even if it had handles and would you settle for grass clippings and a blow-up doll?

                        So with that we continue building......
                        There are some things that need to be done prior to sealing up the hull. One is the area the prop bearing will go. There is a thin wall there that was easy to just cut out.
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                        There are some walls on each side of the hulls that are support structure or maybe has another use, I probably should read the instructions. Anyway, to remove the walls, I used a x-acto blade to score the base of the dividers and the curved walls. Then snipped down to the base.
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                        Once the wall is separated on each side, then bend the wall and it will split on the area that you scored with the blade.
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                        For fun I used the sub-driver foundations as a guide to draw the curve of the sub-driver. Scored along the line and "snapped" out the piece. This is not necessary, this is me playing. I will probably end up cutting this out eventually.
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                        The bow had an area that could trap a lot of air, so I cut out most of it.
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                        Morked on the upper rudder support where I will need to drill a hole.
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                        Also laid the rudder assembly into the notches and marked the range of reach the horn has.
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                        CA'd the bearing foundation to one hull side. Tested the two halves together to make sure they fit good. Also before attaching the bearing foundation, check the fit there is a right fit and wrong.
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                        Ground out the area holding it up to the light. It is very thin, but still the horn did not travel all the way around. It still hit the hull. That may be O.K., it looked like a lot of range is there, but if necessary there is a little room on the horn that can be shaved down.
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                        I did a kit review on the Gato, Aluminaut, and a simple one on the Skipjack. I am not doing this here because you will see the great details as it is built. There are some notable touches like the thinning of the walls near the holes to give them a scale thickness. Very cool.
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                        Using a cohesive glue worked my way around the sub's hull seam. You can also see the mark for drilling out on the upper rudder support.
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                        Fot he most part everything fit together well. Worked my way around the sub in sections. So, now it is sitting to dry overnight.
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                        I will need to build a holder to mark the hull and another for holding the Dremel to saw the hull open. With Thanksgiving coming up this week, sub work space will be hard to come by, but I will try to do what I can.
                        Last edited by trout; 11-25-2013, 05:57 AM.
                        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

                        • Subculture
                          Admiral
                          • Feb 2009
                          • 2119

                          #13
                          A technique I've seen used for routing control links into tight areas is to use pulleys, not toothed pulleys though. They used a round pulley (custom machined- easy when you have a lathe) with fishing wire- the metal stuff which won't stretch. Tensioned up it has sufficient grip so that it doesn't slip. You can route the wires to a more accessible part of the boat where it mates up with another pull which can be actuated with a conventional push rod.

                          Toothed pulleys would also work, but tend to be on the large side.

                          Make sense?

                          BTW, Norbert's book is tricky, but stick with it, it makes life much easier later on especially if you plan to design and build boats from scratch.

                          Comment

                          • trout
                            Admiral
                            • Jul 2011
                            • 3545

                            #14
                            Thank you Andy! Using a cable is a great idea, so I will store that for future use. On this build I am using the fittings kit that goes with the Bronco Type XXIII. There are at least 4 or 5 more subs I want to build before I try making one from scratch. I already know which sub I want to do.

                            Albion, I just read through your Koryu Type D build. Very informative and is something that would work for this build. The decision is will I want to tackle 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

                            • trout
                              Admiral
                              • Jul 2011
                              • 3545

                              #15
                              Come and listen to a story about a man named Jed
                              A poor mountaineer, barely kept his family fed,
                              Then one day he was shootin at some food,
                              And up through the ground came a bubblin crude.
                              Oil that is, black gold, Texas tea.
                              Well the first thing you know ol Jed's a millionaire....

                              I am not Jed, but you might think that with this contraption.
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                              It worked for the most part.
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                              My hold down technique leaves a lot to be desired. Surprisingly it held the sub pretty good for getting the cut line laid out.
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                              The bow vertical cut is just behind the rectangle square on the bow and the aft vertical cut is along a scribe line.
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                              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

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