Scratch-built 1/96 Oscar II

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  • KevinMC
    SubCommittee Member
    • Sep 2005
    • 463

    #46
    Progress!

    Okay, here's a shot of

    Progress!

    Okay, here's a shot of the glass cloth I was talking about using]http://www.subcommittee.com/forum/Glass_cloth.jpg[/img]

    I've included a close-up to show the difference between what I've referred to as open weave (right) and closed weave (left). The open weave cloth was easily molded to the shape of the hull, no so with the closed weave cloth.


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    And here's what it looks like when it's all stuck down on the hull and quick pass with the 80 grit paper:


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    And again from the rear quarter:


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    While I was waiting for the epoxy to cure, I also had a go at making the sail. Once again, this was done with foam for speed and simplicity. Because of the amount of rounding necessary at the top of the sail, I chose to make the top 1/2" out of balsa. This actually worked out very well when I went to taper the sides of the sail because it gave me a clear depth to sand down to. The basic construction process was as follows: I started out by hot-wiring a piece of foam to the correct height for the sail minus 1/2". To this I Super-77'd a piece of 1/16" plywood to act as a base. Next, glue a paper template (which defines the foot-print of the sail) to the plywood. Cut this out on the bandsaw and set aside. Now, cut out the top portion of the sail (a little bit smaller than the base of the sail) from 1/2" balsa and glue to the top of the sail being careful to get it right in the center. Now sand away exposed foam and round the top corners of the sail. Voila! Nearly instant sail. As seen in the photos above, the sail also has a first coat of epoxy painted on. One thing I discovered when glassing the hull is that the foam has a real propensity to suck epoxy right out of the cloth. (On the hull this has resulted in a few dry spots in the 6oz cloth which may become an issue down the road.) To avoid this I wanted to try to seal the foam with an initial coat of epoxy, then I'll put some cloth down to harden up the surface for finishing.
    Last edited by salmon; 04-07-2020, 03:14 PM.
    Kevin McLeod - OSCAR II driver
    KMc Designs

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    • mylo
      Junior Member
      • Aug 2005
      • 723

      #47
      Kevin,

      I've seen other guys

      Kevin,

      I've seen other guys use duct tape over the foam plug before glassing. Would this be to avoid the problem you mentioned of the epoxy getting "sucked" through the cloth ? ....or would this taping process create it's own problems ?

      You are cruising with this baby. I like your simple (yet highly effective) approach.

      Am I correct in saying that one of those little band saws is a real must have for these scratch builds ?

      Myles.

      Comment

      • KevinMC
        SubCommittee Member
        • Sep 2005
        • 463

        #48
        Okay, looking back on this

        Okay, looking back on this I know I made a huge jump so I'll try to catch a few more steps along the way...

        I also started into building the control surface masters. I decided that I'd make 'em from balsa 'cause it's easy to work with (and I have tonnes on hand), then seal them with glass cloth in a vac-bag machine.

        Step one was to get my side view template, and then to cut that out on the balsa.


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        And after...


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        Once the outline is established the surface needs to be sanded down to a nice "foil" shape. Before doing anything though, we need to carefully mark the centerline around the surface. This was done by laying the fin down on the table next to a drafting pencil (and marking device will do) and blocking up the drafting pencil to exactly half the height of the surface using a stack of old business cards. Hold the pencil in place and carefully draw the fin along the pencil, working your way all the way around the fin. Once complete, draw an airfoil shape on the tip and root surfaces. Now get out a block plane and the sanding block and start shaping the balsa to the airfoil shape. (I specifically used balsa because I could use a block plane on it when shaping to cut down on the amount of dust in the shop.)

        Here's a shot of the fin, shaped and glassed. The observant among you will not that this is not actaully the same fin as above from the fact that the direction of the grain is different. I decided to make a new fin after having to add some "shims" to the heel of the original to account for the part of the hull that dips out of view between the prop "spines".

        Click image for larger version

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        Last edited by salmon; 04-07-2020, 03:17 PM.
        Kevin McLeod - OSCAR II driver
        KMc Designs

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        • berserk
          Junior Member
          • Sep 2005
          • 45

          #49
          Hi Kevin,

          Nice work! I

          Hi Kevin,

          Nice work! I saw almost similar pictures.



          Comment

          • KevinMC
            SubCommittee Member
            • Sep 2005
            • 463

            #50
            Myles- Duct tape would certainly

            Myles- Duct tape would certainly seal the foam from absorbing the epoxy, but I do want the glass cloth to adhere to the foam as well. It the plug were to be covered in tape, little to no adhesion would occur. (As an aside, I've heard of making a male master and covering it with packing tape to aid in removal of the core...)

            Andreas- Thank you sir! Is the 1/72 scale yours?
            Kevin McLeod - OSCAR II driver
            KMc Designs

            Comment

            • KevinMC
              SubCommittee Member
              • Sep 2005
              • 463

              #51
              Myles- Almost forgot, for this

              Myles- Almost forgot, for this project "Yes!" my bandsaw has seen very good use!
              Kevin McLeod - OSCAR II driver
              KMc Designs

              Comment

              • anonymous

                #52
                Very nice Kevin!

                steve

                Very nice Kevin!

                steve

                Comment

                • wayne frey
                  Junior Member
                  • Aug 2003
                  • 925

                  #53
                  Hands twitching yet,Steve?
                  Question. I

                  Hands twitching yet,Steve?
                  Question. I saw some nice plans to scale for the 1/72 Oscar laying next to it. I tried to copy the Typhoon blueprints to 1/96 and had trouble due to size. The was at a professional outfit. How did that get done?
                  I also saw a nice, wide cogged belt that is absolutely perfect for a larger, strong r/c submarine on one of the german boats(I think it was Manni's Kilo). Where do you get that, and in what ratios?
                  I like the belt drive alot. I actually have no solid basis for the urge to have the wider belt drive, other than it seems to make more sense than what is out there. I could easily be wrong. I am talking for the 1/72 Akula.

                  Comment

                  • wayne frey
                    Junior Member
                    • Aug 2003
                    • 925

                    #54
                    The 1/72 Oscar I refer

                    The 1/72 Oscar I refer to is the german one.

                    Comment

                    • anonymous

                      #55
                      No Wayne. I'm too busy

                      No Wayne. I'm too busy casting up type 17 hulls. Same thing Kevin will be doing if he's not careful! LOL!!

                      Steve

                      Comment

                      • KevinMC
                        SubCommittee Member
                        • Sep 2005
                        • 463

                        #56
                        Steve- That's a risk I'm

                        [color=#000000]Steve- That's a risk I'm willing to take! ]
                        Kevin McLeod - OSCAR II driver
                        KMc Designs

                        Comment

                        • berserk
                          Junior Member
                          • Sep 2005
                          • 45

                          #57
                          Wayne, you're right. It's Mannis

                          Wayne, you're right. It's Mannis Oscar. I find it looks quite similar to Kevins pictures.

                          Comment

                          • mylo
                            Junior Member
                            • Aug 2005
                            • 723

                            #58
                            Kevin,

                            Yes, as far as

                            Kevin,

                            Yes, as far as the "tape on the foam" thing is concerned, those were for "one off" molds where the foam inside was destroyed in the process of making the fibreglass hull.

                            In your next full length photo of your Oscar II, can you put a yard stick / tape measure beside it to give me an idea of scale ?

                            ......I've got to get me one of those band saws. I've got a scroll saw but it seems a little "light duty" for cutting the original hull templates. Works fantastic for the fine detail stuff though. Tools..... a guy has to have tools.

                            Myles.

                            Comment

                            • typ 202
                              Junior Member
                              • Oct 2005
                              • 21

                              #59
                              Kevin--

                              Going back to the

                              [color=#000000]Kevin--

                              Going back to the previous page's subject]

                              Comment

                              • Guest

                                #60
                                Belt drives are easy to

                                Belt drives are easy to find.

                                http://www.hpcgears.co.uk/products.htm

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