D 520 Rhino Build

Discussion in 'Gallery & Designs' started by fimdan, Jan 5, 2006.

  1. fimdan

    fimdan Member

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    More pics

    Hello,

    Another week is gone. The new job is taking a lot of my time but I always try to find a few moments to tinker with this model.

    Check out these images.

    [​IMG]

    [​IMG]

    [​IMG]

    I have redone everything. I fixed all the formers so that they can be offset correctly. I fixed the skin and everything around it. This morning I felt like working on the tail. Everything unrolls fine. I will still have to make all the necessary adjustment for the material thickness.

    One more comment about offsetting curves. Try not to use that tool if you don't have to. From what I have observed, offset changes the curve a little even when you do very simple things. For example, do not use the offset command if you can achieve the same effect with extruding.

    Ok, I hope you like these images. If you would like to have them enlarged, let me know.

    FimDan
  2. Matthias

    Matthias New Member

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    Coming along nicely! How are you skinning your tail surfaces - it looks like you have surface with three curved edges.

    Rhino's developable surfaces routines bug me a bit with this limitation. Any curvature at the ends of a panel is forced into a conical projection around one of the end points in order to maintain a straight edge. This is not a requirement for developability, and it leads to ugly creasing and curvature discontinuities in the surface. The only way (that I've found) to handle the limitation seems to carry the pattern curves beyond the designed edge and then trim back the surface. An option to allow end curvature would be nice!

    Matthias
  3. fimdan

    fimdan Member

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    Hello,

    Here is what I did with the tail.

    1. Create the ideal surface.

    The idea here is to get the tail as close as possible to the ideal. I used "Sweep two rails" to generate a surface that is not developable but can be further simplified for unrolling. It is my starting point.

    [​IMG]


    2. Simplify the surface.

    First step is to extract additional formers from my "ideal" surface. This is done by drawing simple planes and trimming them so that only the sections inside the tail remain.

    [​IMG]

    Once I have my additional formers (yellow in the picture below), I loft them.

    [​IMG]

    This makes the tail section simpler and developable.

    Why this way? I felt like this will give me better visual results than doing it the traditional way. This is, of course, yet to be proven.

    No, I don't think I have surfaces with three curved edges. The only curved edges are the formers. The top and the bottom edges of each surface are lines. Ideally I would love to have some of those top edges curved and I may have to tackle this problem soon (rudder) but for now I think what I have done is ok.

    Thanks for your comments and questions. I am waiting for more.

    FimDan
  4. Matthias

    Matthias New Member

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    Makes perfect sense. That is what I've been working with as well. For modeling ship hulls, it is far easier to start with a fair surface and then subdivide and simplify with developable panels, as you have done.

    The isocurves for from the sweep2 operation threw me off, but the panel I was wondering about was the last one in the rudder. The shaping at the top is easy to fudge in card but tricky to represent cleanly in hard numbers...

    Matthias
  5. Maurice

    Maurice Member

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    Can you show which 2 rails you swept and with which curve to generate the undevelopable surface. I think I've got it but not certain.
  6. fimdan

    fimdan Member

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    Sweep2rail

    Hey

    Here is the order in which I supplied curves to the sweep2rail command.

    [​IMG]

    Thanks

    FimDan
  7. fimdan

    fimdan Member

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    More goodies.

    This is how I will organize the tail.

    [​IMG]

    Below is something that I am a little worried about. Creating smaller patches that are developable makes the overall surface less accurate. As you can see in my image, the surfaces do not extend as far as they should. I just wonder how this will affect everything.

    [​IMG]

    FimDan