K800

Discussion in 'Sailboats' started by Schoonner, Dec 19, 2011.

  1. Schoonner
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    Schoonner Senior Member

    The umbrella rod was not long enough, so I used a piece from the end of the rod that I found inside the rod which made up the support for the end to keep it from getting crushed (It's hollow) by shear forces and cut the flared end off. Then I used part of another rod from an identical umbrella that My Aunt gave me which was also broken and slid the plug into both pieces so that it is in the center of the joint. Now I have the full 98cm mast.

    My first attempt to make the full length mast is by using a bulb keel which will be significantly heavier than the full size fixed bulb keel weight. I plan on making the keel separate from the rest of the hull so that I can then make different keels with different weights and lengths along the center plane of the hull. I will also try different NACA foils, though I think that a nice thick foil will be better than a thin one.
     
  2. Schoonner
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    Schoonner Senior Member

    YAY! it actually turned out to be pretty nice!

    I taped it down into the corner of a piece of furniture that used to be a water bed headboard while the gorilla glue dried and it actually came out pretty darned straight. It is a tiny bit heavier towards one end, so I guess I'll put that end on the bottom =0)
     
  3. Perm Stress
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    Perm Stress Senior Member

    At 60cm LOA, (and speeds determined by it) thin foils would be better (and certainly simpler to make), because of very low Reynolds numbers involved.
    i.e. at this size and speed, water behaviour around foil is more like thin syrup, than water as we know it from everyday life.
    Some sources even claim that simple flat plate is not that inferior to proper foil at such small speeds.
    Just make sure you have 2-3 times more foil area than full size thing.

    NASA foils are developed for Reynolds numbers in the order of millions, on your foils there will only be X0'000 to 100'000 at most. It is an area of flow regimes, where wings of insects operate. And they never have a section shape similar to the NASA foils.
     
  4. Schoonner
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    Schoonner Senior Member

    Okay cool then That's why the RC models have thin ones then. It would be simple to do more of a flat panel out of a piece of plastic with a length of lead bar along the bottom for ballast.
     
  5. Schoonner
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    Schoonner Senior Member

    Due to knowing better how to scale down the weights I realized that maybe my 1-24th scale model that I made may actually not be as overweight as I thought!!

    1) model length is 3dm so when cubed is 27

    2) full size 79.3 dm cubed is 498677.257

    3) model to full size is 498677.257/27 = 13464285.939

    4)full size to model is 27/ 498677.257 = 0.000054143

    So, 350kgs * 0.000054143 = 0.018950132kgs

    0.018950132 is WAY less than I thought the ballast should be!!

    EDIT:: I could put WAY more on her the way she is, but once I make the deck that will be less. I bet I could use a 30 caliber boat tailed bullet and it would make a nice ballast with a nice shape and everything. Full metal jacket even. =0)

    Then she might be named 'Bullet' LOL!!!

    EDIT2:: yeah, cause a 200 grain bullet is a little more than 11 grams. =0) Then I just pour some lead, to finish the boat tail down to a point and wrap part of the keel with copper wire to make it all just shy of 300 grains. !! I likes that idea!!
     
  6. Schoonner
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    Schoonner Senior Member

    I made a mast hole cutting device. I made cuts into the soft plastic with the hack saw blade. The cuts are at a 23 degree angle so they will bite and cut rather than rip. Once I dig out the center that is left I will glue the plastic in place and it will become the support for the mast. I know that having the right tools is better, but my ex roommate con artists took most of the tools I had.

    [​IMG]

    Uploaded with ImageShack.us


    Look, it actually works!! LOL!



    [​IMG]

    Uploaded with ImageShack.us
     
  7. Schoonner
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    Schoonner Senior Member

    LOL! I almost don't need to glue it in there!!

    EDIT:: Well, it's not perfectly straight up and down, but that's OK because I can cut the hole a little bigger and use pieces of wood to shim it in place while it dries. =0)
     
  8. Schoonner
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    Schoonner Senior Member

    Looks like maybe I used enough glue. LOL!

    [​IMG]

    Uploaded with ImageShack.us
     
  9. Schoonner
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    Location: Washington State USA

    Schoonner Senior Member

  10. Schoonner
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    Location: Washington State USA

    Schoonner Senior Member

    A sail pattern made from sailcut CAD. pretty generic with 18% twist, 2%,7%, and 9% camber set at 50%chord. (I want to be able to point pretty high upwind since I have not really had an actual floating and good working RC before.)

    [​IMG]

    Uploaded with ImageShack.us
     
  11. Schoonner
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    Schoonner Senior Member

    In order to complete some testing I wrapped the hull in some plastic to keep the spackling dry and floated her. SPLASH!!

    I have found that it takes about 1.2kgs to make her sit close to the waterline.

    I am really disappointed with the stability though. I thought it would be lots more stable, but I put in the mast with about 1300grams hanging off the makeshift keel and it won't even hold up the mast. Maybe the mast is just too heavy:?::mad:

    [​IMG]

    Uploaded with ImageShack.us

    EDIT:: I found that the mast is actually way too heavy at about 1800grams. I guess that even carbon fiber weighs too much at that diameter. It is hollow, but maybe the walls are just too thick? I don't know what to try using for a mast now.:(:mad::rolleyes: well, I'll come up with SOMETHING...
     
    Last edited: Jan 18, 2012
  12. Schoonner
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    Schoonner Senior Member

    When I lifted her out, I realized there was a problem with the weight as it was only hanging on by a thread. I guess I should have waited longer for the glue to set before sticking it in the water. Oh well. Will try again tomorrow.
     
  13. Schoonner
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    Schoonner Senior Member

    I was playing around with the mast and knocked against a door frame and what came out? Not pits of foam like I'd imagined might happen, but dirt. Lots of it. Hummm maybe it's not too heavy after all!?! I am trying to figure out how to get all the dirt out. I wonder how it got in there...
     
  14. Schoonner
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    Schoonner Senior Member

    Looking at other people's masts, I think mine is way overkill. I need something like a fishing rod or something smaller around.
     

  15. Doug Lord
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    Doug Lord Flight Ready

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