1/96 Albacore (after Phase III coversion 1961)

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  • Davidh
    Captain
    • Nov 2010
    • 719

    #76
    Hi Scott,

    i am am so jealous, your parts pop out, pristine, DARN YOU!! could you give me more details of this Queensland mob. What is the exact product. Do tell......

    David H

    Comment

    • HardRock
      Vice Admiral
      • Mar 2013
      • 1609

      #77
      Its great stuff. Technirez thyxotic blue gelcoat; R2529 resin and H2429 hardner. Its compatable with West System epoxy too. You can order it through Fiberglass Australia.

      Comment

      • HardRock
        Vice Admiral
        • Mar 2013
        • 1609

        #78
        its raining up here today ans so there was a bit of time for a play in the shed. The Albacore will need some form of gearbox and I have experimented with three or four differend designs over the last few years. All of those old designs took a single engine input and split it into contra rotating, co-axial shafts. They all worked but there was a lot of friction and they all suffered when immerced in water. This time I am going to use a twin engine SD; the one that I use in the Zulu and make a simpler twin input design. Like this;

        Click image for larger version

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        The props that David is making will have a 1/8" bore. I'm using a 3mm outer shaft and a 2mm inner shaft. The simple solution to this mismatch was to solder a sleve onto the outer shaft to bring it up to 3.2mm where it will carry the forward prop. While I was at it I added a .8mm round key. I'll cut a small keyway in the bore of that prop when I get ahold of it so that it slides onto the sleve and the key locks it in place. The inner shaft was a bit easier. I took a piece of 1/8" stainless tube and bored most of it out to 2mm. I then cut an M2 thread into the last 1/4" so that I can screw the rear prop onto it.
        Click image for larger version

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

          #79
          Originally posted by HardRock
          its raining up here today ans so there was a bit of time for a play in the shed. The Albacore will need some form of gearbox and I have experimented with three or four differend designs over the last few years. All of those old designs took a single engine input and split it into contra rotating, co-axial shafts. They all worked but there was a lot of friction and they all suffered when immerced in water. This time I am going to use a twin engine SD; the one that I use in the Zulu and make a simpler twin input design. Like this;

          Click image for larger version

Name:	PA080231.jpg
Views:	253
Size:	575.3 KB
ID:	127877

          The props that David is making will have a 1/8" bore. I'm using a 3mm outer shaft and a 2mm inner shaft. The simple solution to this mismatch was to solder a sleve onto the outer shaft to bring it up to 3.2mm where it will carry the forward prop. While I was at it I added a .8mm round key. I'll cut a small keyway in the bore of that prop when I get ahold of it so that it slides onto the sleve and the key locks it in place. The inner shaft was a bit easier. I took a piece of 1/8" stainless tube and bored most of it out to 2mm. I then cut an M2 thread into the last 1/4" so that I can screw the rear prop onto it.
          Click image for larger version

Name:	PA080233.jpg
Views:	229
Size:	25.8 KB
ID:	127878
          No doubt you're a helicopter jockey -- all that complexity for a gear-box!

          KISS, you moron!

          Inner shaft directly driven by one motor, the outer shaft driven by a gear that girdles it which is driven by a gear of like diameter by the other motor. Done! A sloppy fit between those gears mitigates water-hammer effects.

          KISS, damit! …. KISS

          You people!

          David
          The Horrible
          Who is John Galt?

          Comment

          • DrSchmidt
            Captain
            • Apr 2014
            • 919

            #80
            Why all the mechanics? Why don't you take a slow spinning brushless motor and connect the inner schaft to the shaft of the motor and the outer shaft to the motor housing? Inherently momentum-free.....

            Comment

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

              #81
              Originally posted by DrSchmidt
              Why all the mechanics? Why don't you take a slow spinning brushless motor and connect the inner schaft to the shaft of the motor and the outer shaft to the motor housing? Inherently momentum-free.....
              Absolutely. Torque balanced, simple, and those motors take well to fresh water. Good call, Doctor.

              David
              Who is John Galt?

              Comment

              • JHapprich
                Captain
                • Oct 2017
                • 714

                #82
                Originally posted by DrSchmidt
                Why all the mechanics? Why don't you take a slow spinning brushless motor and connect the inner schaft to the shaft of the motor and the outer shaft to the motor housing? Inherently momentum-free.....
                Maybe i am wrong, but isnt there still actio=reactio. Would not the engine disable itself with such an arrangement? And how would one attach it to the hull?

                Comment

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

                  #83
                  Originally posted by JHapprich

                  Maybe i am wrong, but isnt there still actio=reactio. Would not the engine disable itself with such an arrangement? And how would one attach it to the hull?
                  Both the motor body and motor armature are on bearings that permit rotation. Power is fed to the motor through slip-rings. Such an arrangement was a feature of the MK 37 torpedo. Crazy on first consideration, but turns out to be a dirt-simple solution to the concentric shaft counter-rotation problem.

                  David
                  Who is John Galt?

                  Comment

                  • JHapprich
                    Captain
                    • Oct 2017
                    • 714

                    #84
                    Fascinating.but were would i get souch engine? Jörg

                    Comment

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

                      #85
                      Originally posted by JHapprich
                      Fascinating.but were would i get souch engine? Jörg
                      Buy an 'outrunner' type brushless motor and modify it with a case bearing and slip-rings. Not for beginners!

                      David
                      Who is John Galt?

                      Comment

                      • HardRock
                        Vice Admiral
                        • Mar 2013
                        • 1609

                        #86
                        Originally posted by He Who Shall Not Be Named

                        No doubt you're a helicopter jockey -- all that complexity for a gear-box!

                        KISS, you moron!

                        Inner shaft directly driven by one motor, the outer shaft driven by a gear that girdles it which is driven by a gear of like diameter by the other motor. Done! A sloppy fit between those gears mitigates water-hammer effects.

                        KISS, damit! …. KISS

                        You people!

                        David
                        The Horrible
                        Well yes.....but no. There isn't enough room in the arse of this thing to allow much of a dog bone connection to anything. I didn't show it in the photographs but the two driven shafts line up perfectly with the output shafts of the SD. Two pieces of silicon tube will make the connection both simple, direct and noise free. No room for a wet motor either unfortunately although I did consider using a tandem out rigger (but then I realised that I sent the only one I had to YOU!) Helicopters rule - wings are for faries!

                        Comment

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

                          #87
                          Originally posted by HardRock

                          Well yes.....but no. There isn't enough room in the arse of this thing to allow much of a dog bone connection to anything. I didn't show it in the photographs but the two driven shafts line up perfectly with the output shafts of the SD. Two pieces of silicon tube will make the connection both simple, direct and noise free. No room for a wet motor either unfortunately although I did consider using a tandem out rigger (but then I realised that I sent the only one I had to YOU!) Helicopters rule - wings are for faries!
                          Helicopters don't fly … they simply beat the air into submission!

                          I hear you about the 'not enough room' issue. I'm working on a very short SD that will leave room for more mechanicals in the ass-end. I'm thinking of replacing the micro servos with linear microbe-sized servos -- that will free up a lot of space. Film at Eleven.

                          David
                          Who is John Galt?

                          Comment

                          • HardRock
                            Vice Admiral
                            • Mar 2013
                            • 1609

                            #88
                            Originally posted by DrSchmidt
                            Why all the mechanics? Why don't you take a slow spinning brushless motor and connect the inner schaft to the shaft of the motor and the outer shaft to the motor housing? Inherently momentum-free.....
                            And inherently impossible to purchase. This set up cost me exactly nothing. Made from old gears and spare bearing and shafts and it fits in the rear of the sub quite nicely.

                            Comment

                            • DrSchmidt
                              Captain
                              • Apr 2014
                              • 919

                              #89
                              One can actually buy that stuff......

                              https://www.aliexpress.com/item/Free...423300270.html

                              http://www.maxxprod.com/mpi/mpi-266.html
                              Last edited by DrSchmidt; 10-09-2018, 05:44 AM.

                              Comment

                              • HardRock
                                Vice Admiral
                                • Mar 2013
                                • 1609

                                #90
                                Yep. I have one of the smaller ones some time ago that I was planning to use. In the end I sent it to David to play with. I've never run a motor in the wet. Wonder what the life span would be.

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