Elliptical Submarine Hulls

Discussion in 'Boat Design' started by Asleep Helmsman, Jan 16, 2010.

  1. haru
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    haru Junior Member

    You're welcome. I hope it helps getting insights. :)

    Here's a backup link from some forum in case the site has problems.
    http://www.tech-domain.com/thread-18979-1-9.html
    links to other pages are at the bottom; this is the last page (last url number)

    I was digging papers on hulls maybe I will find something for this thread.
     
  2. Asleep Helmsman
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    Asleep Helmsman Senior Member

    Here is the beginnings of a hull design.

    Edited: attached is an ellipsoid of approximately the same dimensions as the sub.

    I do have a piece of advice, for anyone attempting to design using ellipses.

    There is a time when you might want to change some of the elements to arcs.

    When designing in 3D ellipses, it’s very easy to lose track of interceptions and predictions of overall curves.

    You will find many times that as you zoom into certain areas; an ark will follow an ellipse very closely, sometimes within .003 of an inch or so; well below construction error and even below hand sanding resolution.

    One of the main considerations is to keep positive curves positive and negative ones negative. Fortunately AutoCAD offers a loft command which is very powerful up to a point. When dealing with ellipses, AutoCAD chokes when the variables approach zero. Which is in effect infinity, when considering the ratio of change relative to an end point on a line.

    Remember advice is free.

    Coming Soon a method for constructing modified ellipses to create sharp edges. Useful for surface piercing hulls and trailing edge of submerged ones.
     

    Attached Files:

    Last edited: Jan 19, 2010
  3. Leo Lazauskas
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    Leo Lazauskas Senior Member

    It looks like a standard ellipsoid to me. Is there something "parabolic" I am not seeing?

    Cheers,
    Leo.
     
  4. Asleep Helmsman
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    Asleep Helmsman Senior Member


    You’re absolutely correct there are no parabolas in there. But half of an ellipse behaves similarly to a parabola, and many of the sections in the actual model are not entire ellipses.
    Lastly you say standard ellipsoid like every one knows them. Well I’m completely self taught and sometimes I discover things that are apparently ubiquitous.
     
  5. Asleep Helmsman
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    Asleep Helmsman Senior Member

    Thank you,
     
  6. haru
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    haru Junior Member

    Normal is relative :lol: but it is a typical 3d ellipsoid. Many things can change so this is alright.

    So, how many decks will it have?
    Now that I think about it, if it's too thin then the ratio between gangway and room width is bad. Well, in the past sleeping banks were on the side walls so it's not something unacceptable but moral will suffer.


    Btw. I found something interesting:
    http://www.subtech.uk.com/acatalog/The_Albacore_and_Marlin_Submarine_Range.html
    Look at the arrangement of the tail fins. They are alternately staggered to lower turbulence.
     
  7. Asleep Helmsman
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    Asleep Helmsman Senior Member

    This whole thing is only 4 feet (1.2 meters) long
     
  8. haru
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    haru Junior Member

    I see, so will it become a full functional RC model of just for design/testing purposes?

    Btw. anybody know what frequencies do work under water?
    I know 21 cm is ideal.
     
  9. Asleep Helmsman
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    Asleep Helmsman Senior Member

    Autonomous and preprogrammed mission parameters. It’s basically a hunter- seeker with an expressed mission to seek out mermaid life forms.
     
  10. haru
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    haru Junior Member

    Now I'm disappointed, but got more interested in model building. :lol: (shootable torps...)

    Anyway. looking into the Albacore it seems control surfaces will pose quite a lot of drag. Well, I guess for a UUV you can just use propulsors. That is if speed isn't an important requirement.
     
  11. Asleep Helmsman
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    Asleep Helmsman Senior Member

    With most bottom mapping UUVs speed is not really very important. The reason to reduce drag is to save energy.
     
  12. haru
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    haru Junior Member

    I see.
    In this case drag might become less important.
    The UUV will probably weight around 100+ kg so it will need lots of power. Each propulsor will come with drag that are probably not much less than control surfaces. You will need to know how manoeuverable it need to be, and hence, the number of propulsors. (1 would be nice) Also if it uses sonar for mapping, you have to consider noise from the propulsor(s). You may not be able to place it anywhere (close as) you want. Well, that's what I think, but without simulation results from here on there are many possibilities.
     
  13. Asleep Helmsman
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    Asleep Helmsman Senior Member

    The larger the prop the better.
     
  14. haru
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    haru Junior Member

    Yes.

    Just a thought, you might want to look up about how to transport it. Operators might want to have certain requirements. You would save trouble later.
     

  15. Asleep Helmsman
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    Asleep Helmsman Senior Member

    Here’s a question.
    Can anyone see a reason why the areas of maximum beams have to be in the same location along the hull?
    In a surface boat, this would translate to the maximum draw, not lining up with the maximum beam, measured along a longitudinal line. Excluding any keel considerations.
     
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