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Japanese BI I-25 in 1/72

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  • He Who Shall Not Be Named
    replied
    He'll simply re-establish submerged trim with the WTC in place, less the ballast tank, then build a ballast tank that contains the same number of cubic inches as his hunk of exceptionally ugly foam. Done.

    In the early years of the game (the 80's Renascence of r/c submarining in America, led by Skip Asay, Dave Weeks, Mike Dorey, and others) David Copeland advocated just this very method of determining a boats ballast tanks displacement.

    David,

    Leave a comment:


  • greenman407
    replied
    Absolutely but maybe I missed it. Your tests were without a WTC. So until you get one in there and test it you dont know what you have. Unless I am missing something.

    Leave a comment:


  • He Who Shall Not Be Named
    replied
    Your assumptions are correct for the conditions established.

    David,

    Leave a comment:


  • oztruck
    replied
    Think of it this way greenman407.

    The ballast tank size will determine how your boat sits in the water. I might be wrong but I think its size is critical

    1a: If my boat without its WTC is sitting in the water with just the top part of the sail sticking out, it has just a bit of positive buoyancy. correct

    2a: Now to get it to the correct surfaced water line, through trial and error I found my foam block has to be 10" long to displace enough water.

    now take that one step further

    1b: My boat with its WTC is sitting in the water with just the top part of the sail sticking out, it has just a bit of positive buoyancy. Same buoyancy as above in 1a. correct

    2b: Now to get it to the correct surfaced water line, I found my ballast tank has to be 10" long to displace enough water.

    All the ballast tank (10"foam block) is lifting out of the water is the deck, conning tower and the part of the hull above the water line.

    Does that make sense?

    Leave a comment:


  • greenman407
    replied
    I think that this is where it gets complicated for me, probably not for the rest of you. Oztruck has determined that a 10" block of styro is what he needs to displace that same volume of water to get his sub trimmed. Well obviously a WTC will add bouancy and weight. So im not sure how sizing a styrofoam block will help. I do it the lazy way. I just ask Dave what size WTC will work. Then I stick it in and then trim for that. Ill be interested in where you go from here. Now if you are going to build a seperate WTC for the ballast tank then you would install the WTC that houses your Battery and electronics first and then see whats left in order to size your ballast tank. Right??

    Leave a comment:


  • oztruck
    replied
    Started on the drive unit.





    They have a 3/1 reduction. Looking that they will give me plenty of power and a good long run time.

    I don't have any clear water here in South Australia to put my boats into.

    Most of the time it is either green or coffee colored.

    The best place I have found uses boar water but it is only 2 1/2 feet deep, so speed is not a big thing with my subs. Long run times and steady depth control as you can imagine are very important.

    It's hard to drive when you can't see where it is.Scuba Diving

    Leave a comment:


  • oztruck
    replied
    Oh well, looks like that request went down like a sub with the hatches still open. I guess I will have to make myself one.

    Leave a comment:


  • He Who Shall Not Be Named
    replied
    Originally posted by oztruck View Post
    Any one want to donate a 3" X 28" WTC. (he says with a smile)
    You cheap *******, you!

    Buy one of our GATO SD's -- I'll make one with a long ballast tank for you.

    David,

    Leave a comment:


  • Rpmtech1
    replied
    dunno.... women, wine, slaves etc.

    Lexan tubes dont grow on trees! LOLz

    Leave a comment:


  • oztruck
    replied
    What could I offer to a man who has the world at his fingertips?

    Leave a comment:


  • Rpmtech1
    replied
    And if I did, what would i get out of the deal :)

    Leave a comment:


  • oztruck
    replied
    Any one want to donate a 3" X 28" WTC. (he says with a smile)

    Leave a comment:


  • Rpmtech1
    replied
    Nice, that looks great! This will be one nice, very unique boat when done. I like it.

    Leave a comment:


  • oztruck
    replied
    Thanks Boss for the encouragement. Now that I know that I am on the correct path, it's on to the next level.

    And for the master chef who does some fine cooking

    Before


    After

    Leave a comment:


  • Rpmtech1
    replied
    Before and after shots of the bow? isnt that the main problem with this model

    Leave a comment:

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