Internal Frame Help: Beta Builders Wanted

Discussion in 'Gallery & Designs' started by Paragon, Apr 1, 2008.

  1. Paragon

    Paragon Active Member

    So I'm currently designing a model of the Beriev Be-200 seaplane, and was constructing the fuselage yesterday. Upon completion, I noticed that the fuselage was somewhat twisted, the tail and nose were not level with each other. I used some internal braces with this model, but only two, right in the middle. I think they might be the wrong shape, but I wanted to know if there was any other factors I should think about fixing to get the fuselage straight, anything you more experienced modellers might know. Should I divide the fuselage into more parts? Should the internal structure be more extensive?

    Here are some images of the problematic fuselage to help with diagnosis. I'll include pictures of the parts soon.


    Also, I could use some beta builders on this one, its more complex than some of my other models.
  2. Jaybats

    Jaybats Member

    looks like you just need to compensate for the increased outer area toward the rear of the fuselage. the rear of the cylinder needs to fan out a little more than the front because the flattened rear/bottom part requires more area than what the circumference of the regular cylinder can provide.

    an alternative is to build the rear/bottom part as a separate piece, and indicate a portion to be cut out from the rear of the fuselage cylinder.
  3. Paragon

    Paragon Active Member

    Could you maybe explain it a little differently? I don't really follow you.

    Just a note, the fuselage is constructed in one large piece in the middle, two smaller parts for the back when the width gets thinner, and a seperate part for the cockpit. The entire blue bottom is also seperate.
  4. Jaybats

    Jaybats Member, when the fuselage piece is flat, it should sort of look like a fan rather than a rectangle.
    . . . ----...
    . . / . . . \
    . / . . . . . \

    From what i can tell from the pictures, the twist seems to start from the middle, and indicates either the textures may not be aligned, or circumference starting from the middle is off by a few millimetres, and the difference gets progressively larger to the rear.

    It could also be due to distortion brought about by the shape of the bottom/hull, since it kind of bevels/cuts the cylinder at a tangent; that's not easy to estimate since you're dealing with the curve (different angles between front and back), and it's also tapering down into a smaller area towards the rear. so i think you just need compensate by adding an incrementally increasing area to the fuselage at the points where the rear meets the flattened bottom, in order to keep the top part straight.

    i hope that makes sense! :mrgreen:
  5. Paragon

    Paragon Active Member

    Ok, I get it. First, the end pieces are "fans" instead of rectangles, because they do vary in circumference. The center piece on the other hand, is not intended to vary in width (the bottom makes up for the difference in circumference) so the middle piece should be a "rectangle". Also, the texture is mirrored at exactly 180 degrees (according to Photoshop), so I'm pretty sure that's not the issue.

    I do agree that the problem is probably caused by the way the bottom meets with the top piece, but I don't understand what you mean about incrementally increasing the area. The only thing that comes to mind is that you mean a piece should look like this:


    ...which a few of them already do (where applicable). Honestly, I have a feeling its a misalignment of the bottom piece that's the culprit, coupled with some poorly measured internal braces, and I really need to figure out how to get around that.
  6. Paragon

    Paragon Active Member

    This might help a little:

  7. Jaybats

    Jaybats Member

    scratch the fan idea, now that i see you've already got it on the lay-out.

    the upper right curving corner of the large fuselage piece is not exactly symmetrical with the lower right...there's a small extra space above the line which is not reflected in the lower corner; maybe that's the culprit?
  8. Paragon

    Paragon Active Member

    You're right, it could contribute to it, but the warping begins a little before that point. I'm trying to construct another copy of it with modified internal braces that I'm sure utilize the same width, but I'll be sure to trim the rearward end of the large piece to be symmetrical as well.

    Another idea I had was putting the bottom pieces together to make sure there wasn't any overlap during construction that might throw it off, though that would weaken the crest.
  9. Paragon

    Paragon Active Member

    Anybody else have input?
  10. I love sea planes so if you still need Beta Builders let me know. Or put me on the list when it's available.

    Thanks ,Tim
  11. Paragon

    Paragon Active Member

    Yeah, I actually solved the problem, it looked like it was mostly a construction issue. The model is now available on my website.

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