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  • David,

    Relating to the pitchdown effect, at mine it only occurs at topspeed, i"ve set the speedcontrol at max 3/4, i suspect it has to do with the hydrodynamic effect of the tower, don"t know if others have the same problem.
    So, the V80 is next on the list, has to cured by now.

    Manfred.



    I went underground

    Comment


    • Originally posted by MFR1964 View Post
      David,

      Relating to the pitchdown effect, at mine it only occurs at topspeed, i"ve set the speedcontrol at max 3/4, i suspect it has to do with the hydrodynamic effect of the tower, don"t know if others have the same problem.
      So, the V80 is next on the list, has to cured by now.

      Manfred.


      Yeah, your wonderful little V80 hull is rock-solid by now. It's in the rotation. Only 12 models ahead of it. We'll get there, old friend.

      I had a fundamental control problem I never had time to resolve with the Bronco Type-23. It would pitch down the moment it moved, so speed was not the issue. Now, with time to spare, any like problems with the new Type-23 can be resolved.

      David
      Resident Luddite

      Comment


      • David,

        This sounds more as the levelkeeper or servo flutter, CG you will notice directly, mine is straight under the tower.

        Manfred.
        I went underground

        Comment


        • Originally posted by MFR1964 View Post
          David,

          This sounds more as the levelkeeper or servo flutter, CG you will notice directly, mine is straight under the tower.

          Manfred.
          I hear you. The angle-keeper was observed to do its job: I would hand-hold the model in the water and pitch it up and down, and the stern planes would respond correctly. The boats CG was at the longitudinal center of hull and low, and the ballast tank was centered there as well. Static stability dead in the water was perfect.

          Seemed I had everything set up right, but the damned thing would, once in submerged trim and the throttle advanced, the model would flip me the bird, yell an obsenity at me, then promptly put its tail up in the air and make for the mud.

          David
          Not So Smart After All
          Resident Luddite

          Comment


          • The OTW Type XXIII would do the same thing! My bud, Tony, had one that did that years ago, but I don't recall how (or if) that got fixed.

            Comment


            • Originally posted by wlambing View Post
              The OTW Type XXIII would do the same thing! My bud, Tony, had one that did that years ago, but I don't recall how (or if) that got fixed.
              So... I'm not crazy?!
              Resident Luddite

              Comment


              • Originally posted by wlambing View Post
                The OTW Type XXIII would do the same thing! My bud, Tony, had one that did that years ago, but I don't recall how (or if) that got fixed.
                I never had that happen with my OTW Type XXIII. I debuted the boat at the Subregatta back in the 90s, and never had that issue running it there or anywhere. I used Bob's original on board compressor WTC with it. The only issue I had with that boat was that I made the rear dive plane linkage with too thin brass rod. Full astern would overwhelm the dive plane throw. It needed to be thicker, with a bit more bracing for the control rod as it passed through the rear of the hull. I did run that boat with bow planes, while the rear planes were on a leveler.
                Last edited by goshawk823; 01-12-2022, 02:48 PM.

                Comment


                • Originally posted by He Who Shall Not Be Named View Post

                  So... I'm not crazy?!
                  Oh you do not get off the hook that easily. A working Type XXIII does not release you from being crazy.....look at me :-)
                  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


                  • Originally posted by He Who Shall Not Be Named View Post

                    So... I'm not crazy?!
                    Let’s not get drastic.
                    Of the 40,000 men who served on German submarines, 30,000 never returned.”

                    Comment


                    • After giving it some more thought, the issue may have been due to trapped air in the bow suddenly moving as the boat dived. Once under and at an angle, the bubble either collapsed or shifted aft and dissolved, causing the sudden and abrupt increase in down angle. I will be observant of how my Bronco reacts when she gets sea-trialed again come spring. Previous "tub trials" showed a propensity towards being heavy aft, thus diving stern-first. I have since changed some things around, so all new to me this coming go-around. Good luck with your efforts!!

                      Comment


                      • Originally posted by wlambing View Post
                        After giving it some more thought, the issue may have been due to trapped air in the bow suddenly moving as the boat dived. Once under and at an angle, the bubble either collapsed or shifted aft and dissolved, causing the sudden and abrupt increase in down angle. I will be observant of how my Bronco reacts when she gets sea-trialed again come spring. Previous "tub trials" showed a propensity towards being heavy aft, thus diving stern-first. I have since changed some things around, so all new to me this coming go-around. Good luck with your efforts!!
                        A possibility. My initial reaction to your suggestion was blustering indignation that anyone would DARE question my ability to vent a wet-hull boat. BUTTT.... I've done stupid **** before. No denying that!

                        I'll take your observation into account when I start punching out topside holes. Thanks, Bill. Nothing sounds louder and with more resonance than the words from someone who's been there.

                        (That doesn't get you off the hook, I still owe you terrible consequences for what you did to my poor 1/72 ALFA two seasons ago! You savage!).

                        David
                        Attached Files
                        Resident Luddite

                        Comment



                        • The interlocking registration tabs -- a set in the upper hull, and a set in the lower hull -- hold the longitudinal edges in alignment and pull the halves together when the tabs of the upper hull engaged the inside of the lower hull; the slight 'pull-down' compression of the upper hull tabs to the over-hanging lower hull interior provides this closure force.

                          Last thing to install was the forward and after radial flanges. Here I'm CA'ing the forward radial flange, using the same .020-inch thick polystyrene sheet I employed for the kerf-strips that run the length of the longitudinal edges of the lower hull.

                          One can never have too many clamps!



                          All model parts were given a ruthless scrubbing with an automotive grade surface prep, rubbed in with a green abrasive pad. Prep-sol is one brand. It's a hydrocarbon solvent that is strong enough to cut away grease, oil, dirt, and the like, but not quite strong enough to melt you or your model. Good stuff, and the last thing you do before body or paint work.

                          The scratching of the models surface produces some 'tooth' that adds a mechanical element to the adhesive 'stick' of glues, fillers, putties, primer and paint.



                          There were slight miss-alignments at the radial edges, forward and aft. These low spots would be filled with Bondo automotive filler.

                          The kit was assembled from four hull sections, The radial union between the forward and after hull sections presented a slight distortion around the girth of the hull -- an unfortunate artifact of kit design. (Oh, well, that's why God gave us Bondo). The dip there had to be Bondo'ed as well. All areas to receive Bondo automotive filler were marked with pencil, the hash-marks you see here.

                          #200 grit sandpaper provided the additional tooth needed to insure solid adhesion between the polyester Bondo and polystyrene plastic of the model.



                          (how many of you idiots will fixate on the thumb, but not the presentation?)

                          To keep Bondo away from places that don't need it, I applied masking.



                          After troweling on the Bondo I immediately ran a blade along the slight gap between hull halves. Failure to do so would result in the Bondo permanently 'gluing' the two hull halves together. Something to be avoided.

                          (Stop looking at that thumb!).



                          Bondo applied, the masking was removed and I got to work with rasp and sandpaper to feather the filled areas to the contour of the surrounding surfaces.



                          Once the Bondo had cured hard ('green stage' actually, it takes at least 30 days to cure properly) I ground away at the excess material with a rasp file, followed by hard and soft sanding block. The sanding started with #200 grit and worked down to #400. Both the filing and sanding were done wet to prevent clogging of the tools.



                          Cured Bondo, by itself is porous and weak. To those areas that would be subject to stress, such as the longitudinal and radial edges, I applied thin formula CA over the Bondo'ed areas. The adhesive soaked into the surface of the Bondo and greatly strengthened the substrate. After lightly sanding the CA'ed surfaces, things were ready for some Nitro-Stan air-dry touch-up putty to fill all tool marks and slight pits and dings not addressed by the Bondo.



                          I find air-dry putty is best applied with a brush. If need be the putty can be cut with a little lacquer thinner to make it more brush-friendly.

                          Bondo for contouring and major fill jobs. Putty is for shallow scratches and the like. Don't confuse the two.



                          Deep imperfections get the Bondo. Shallow imperfections get the Nitro-Stan. If applied thin (it should never be applied to depths greater than .030-inch) the putty will dry in about an hour. Regard air-dry putty as that last step before primer. Bondo for the deep ugly stuff; putty for shallow tool-marks and the like.




                          Resident Luddite

                          Comment


                          • Good stuff. I’m particularly fond of the XXIII. It’s simplicity at it’s finest. No guns, or other outside parts like the Type VII models to break. Bare bones, but just a touch of U-boat looks.
                            Of the 40,000 men who served on German submarines, 30,000 never returned.”

                            Comment


                            • Originally posted by Das Boot View Post
                              Good stuff. I’m particularly fond of the XXIII. It’s simplicity at it’s finest. No guns, or other outside parts like the Type VII models to break. Bare bones, but just a touch of U-boat looks.
                              And a hint of what was to come if they had time to get the Type-18 into series production.
                              Resident Luddite

                              Comment


                              • Okay, i got to ask,what's with the thumb?, did you plaster it with bondo?, smeared it under with niitro-stan?, glued it with superglue?, share the gory details.

                                Manfred
                                I went underground

                                Comment

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