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Thread: Modeling Tubular Frame

  1. #1

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    Modeling Tubular Frame

    I'm wanting to build an accurate model of the tubular frame structure of my plane - essentially reverse engineer what already exists. The Solidworks version that is available for EAA members does not seem to include the "tubing" module. My questions are: does the SW tubing module make this work substantially easier? Any tips on how to proceed without this module? I have some pretty good experience using the basic feature set, but never tackled a tubing project. Any and all help is much appreciated!

  2. #2
    cwilliamrose's Avatar
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    Are you saying the Insert|Weldments|Structural Member... menu item and the Weldments toolbar are not there in the EAA version? That would be a huge surprise. I don't have my laptop with me but I can look at my EAA SWx install when I get home.

  3. #3

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    The Weldment features will be there. But you have to add the tube sizes you are using.

    The weldment feature is great for doing tube structures and you can make accurate templates of the mitered joints in a tube structure.

  4. #4
    cwilliamrose's Avatar
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    You can download almost all the tubing sizes you'll ever need from VR3's website. And if you follow their guidelines you can send them your model and get them to do the tube fitting for you.

  5. #5

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    Thanks for pointing me in the right direction. I have never used this feature so I will need to take some time to become familiar with this. I am aware that Solidworks has a module they refer to as "Piping & Tubing" which, I believe, exposes functionality different from the weldments feature and which is not part of the EAA version of SW, but is available in one of the other academic versions. If the weldments feature will allow me to create the tubular frame accurately, then I am good with this – just need to learn a bit more about how this works. I am guessing this all starts with a good mastery of 3D sketching? Again, thanks for the help!
    Last edited by RCS; 06-18-2017 at 01:58 PM.

  6. #6

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    I use the weldment feature frequently and found it very useful. I have modeled the Bearhawk 4 place.

    You start with a 3D sketch of your fuselage. You can do a single drawing or several drawings and you can do a combination of 2D and 3D drawings With those drawings, you add/insert structural elements along the lines in the sketches. After that you trim the elements to each other. Do it right and you can do a FEA analysis of what you have drawn.

    As a profession, I build tube frame formula race cars. I have done the FEA analysis and then actually tested the complete race cars and the empirical results are very close to the SW models.

    The Piping and Tubing module is not what you would use for a tube fuselage.

  7. #7
    cwilliamrose's Avatar
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    Quote Originally Posted by RCS View Post
    .......I am aware that Solidworks has a module they refer to as "Piping & Tubing" which, I believe, exposes functionality different from the weldments feature ........ If the weldments feature will allow me to create the tubular frame accurately, then I am good with this...... I am guessing this all starts with a good mastery of 3D sketching?....
    As mentioned above, the weldment tools are what you need here, the other package is not for creating structures.

    I think my Pitts fuselage (seen here) only has a few 3D sketches which are mainly for the longerons. All the other sketches are 2D. Lots of planes created for those 2D sketches but most using geometry from previous sketches for definition.
    Last edited by cwilliamrose; 06-18-2017 at 06:08 PM.

  8. #8

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    This is great feedback - just exactly what I was hoping for: a starting point with some examples and helpful tips. I'm going to practice and get started. Quite sure I will have more questions - very appreciative of the support! --Rob

  9. #9

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    Thanks to your help here I have built some practices models using the weldments feature - pretty easy! In my aircraft the four outer longerons are slightly curved. So in SW sketch I created a splined curve with points at each station and have them fully dimensioned (all lines are black). However I cannot add the tube to this splined line as I can do with the straight lines. Is there some step that I am missing?

  10. #10
    cwilliamrose's Avatar
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    Tubular aircraft structures are meant to be trusses and the runs between points are almost always (and ideally) straight lines. The exception that comes to mind is the engine mount for four cylinder Lyc's. I believe your primary structure should not have any curved tubes, especially the longerons.

    I'll have to take a look at my engine mount model at the shop tomorrow, that's the only weldment where I used curved tubes. It's been a few years ago since I modeled that part and I don't remember exactly what I did but I'm pretty certain the curves were done as arcs and not splines.

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