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Aerofoil Profile Scripts

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Comments

  • justin_carrolljustin_carroll Member Posts: 4
    @darren_13 thanks for the reply.  The 'thicken' command worked wonderfully.

    I see a script that would allow one to change the thickness of the ribs, size of the negative spaces, and location of the spanwise lightening holes and their dimensions.    Just adding some variables may help a lot.

    Another thing that I am having difficulty with is locating items referenced to the profile.  For example, let's say that at the 1/4 chord location I want to place a hole at the point 1/2 way between the upper and lower surfaces of the profile.  How would this be accomplished?  The 1/4 chord isn't hard but the other measurement is.  

    Again I am relatively new and learning.  Thanks for your time.


  • darren_13darren_13 Member, Developers Posts: 117 PRO
    Hi @justin_carroll, have you tried the lighten feature script? think that might help you a lot. I feel making a script just for this application might not save much time. I presume you have seen the wing structure script that is in the same document? it kinda does that by defining the number of ribs, thickness etc. but at the moment it is limited.

    As for having a kind of centre line, I did play around with this before and I couldn't find an efficient solution for when using aerofoil coordinates (they rarely come in pairs so splitting the difference isn't viable) however I think the NACA 4 digit code comes with a centre line as this is defined by an equation. Maybe I should re-visit this as it was something that annoyed me also.

    The solution I suppose at the moment for set positions would be to draw a line at the 1/4 cord length and between the upper and lower splines and use its centre point for the half, this could also be the automatic solution however it becomes fairly time consuming to generate.

    Let me know your thoughts, and I really appreciate your feedback.
    Darren
  • justin_carrolljustin_carroll Member Posts: 4
    @darren_13 thanks again for the response.  

    Should it be possible to draw a line from the upper to the lower part of the generated profile?  I can't even get the profile to show up when I am working on a sketch, let alone get a line to snap to it.  

    Is it possible to project the profile onto another plane or sketch?  then use the projected profile as a reference?

    Perhaps this post belongs in another area.  This may just be newbie drawing issues.  

    THIS drawing has a hole for a spar.  Positioning the hole is the issue I am working on.  Perhaps my workflow needs to be altered.
    Thanks again.
  • pietro_rossinpietro_rossin Member Posts: 10
    edited April 2018
    Hello
    I'm in a situation similar to @justin_carroll
    I'm planning to 3d print my directional fin with dihedral ribs, so I can print a single shell perimeter with thin ribs inside to reinforce structure.
    I tried to print with honeycomb infill but the result is a bit too heavy..
    I was able to create the loft (solid) and I tried to create the ribs structure extruding a line sketch, using Thicken tool and then using a boolean union.
    My problem is that I can't perform a cut using the part1 as tool (wing part) and ribs as part to cut.
    Here is my project
    https://cad.onshape.com/documents/ba918051923408fe2a89e6e6/w/0b26b8b6cddb75e331c24961/e/25db96c7240e98bb254cba51

    I'm not an engineer and my cad modeling skills are a bit poor..
    Any hint is wellcome.
    Thanks
    Pietro
  • darren_13darren_13 Member, Developers Posts: 117 PRO
    Hi @justin_carroll, yes absolutely you should be able, make a sketch on the same plane as your airfoil and 'use' the upper and lower curves, this makes the curves part of a new sketch and allows for you to directly sketch using them as references.

    Hi, @piero_portini is this what you want?:

    I used the boolean intersect tool.

    let me know if you mean something different. 

    Kind regards,
    Darren
  • pietro_rossinpietro_rossin Member Posts: 10
    Super! That is exactly what I needed, Thanks!
    Now I must figure how to add the external surface, may be using loft surface, thicken and boolean union..
    Thanks again
  • darren_13darren_13 Member, Developers Posts: 117 PRO
    Super! That is exactly what I needed, Thanks!
    Now I must figure how to add the external surface, may be using loft surface, thicken and boolean union..
    Thanks again
    I do the loft thickens and works fine for me, not tried adding it back onto the geometry yet.

    Once it is printed any chance you could post an image?

    Many thanks,
    Darren
  • pietro_rossinpietro_rossin Member Posts: 10
    edited April 2018
    Sure I'll post some images for the new structure. I plan to print in transparent PETG...
    here are my previous test with PLA-wood and PETG black - Honeycomb infill 10%


    Pla Wood is lighter but delaminated




  • darren_13darren_13 Member, Developers Posts: 117 PRO
    @pietro_rossin, that really awesome!! looking forward to your next run :)

    Is there are target weight you are aiming for? or just as low as possible? Also, are you testing its strength?

    Really interesting, thanks for sharing!
    Darren
  • pietro_rossinpietro_rossin Member Posts: 10
    I'll like to stay as low as possible, that is a tail piece...
    For the strength
    I printed half wing of this RC sailplane in PLA.



    Half wing is 750mm more or less and segments are glued with Cyanoacrilic glue.
    I made a test putting a Brick (3,5 Kg more or less) in center with root and tip suspended and it flexes a little and resist..
    That is enough for a little RC sailplane i think

    PETG is much more strong IMO and laminate a lot better than PLA.

    Let's see how it will work

    Thanks again
  • SchenyScheny Member Posts: 5
    Hi Darren!

    Your scripts is simply awesome. I only have the problem that I am using my own airfoils and I don't know how to import them. Does your script have any possibility to import custom ones?

    I already know, that you first have to upload them to your project as Onshape doesn't support local files. If nothing is possible, can I send the profiles to you?

    Best regards,
    Andreas
  • kevin_o_toole_1kevin_o_toole_1 Onshape Employees, Developers, HDM Posts: 449
    edited March 5
    @darren_13
    Adding support for custom files should be pretty easy now. A good example to follow is the FeatureScript Beams feature. You could similarly add a "Custom" option to your feature (alongside DATA and NACA), and for that option, use a CSV reference parameter to allow selecting any CSV data.

    This would allow users of the feature to use their own profile data without needing to add that data to the feature itself.
  • darren_13darren_13 Member, Developers Posts: 117 PRO
    Hi @Scheny @kevin_o_toole_1, I'll have a look and see what's involved, I haven't actively changed the profile script or the more advanced test script in over a year as they serve everything I needed to do, and I am pretty busy these days. However, I imagine one day I might need this myself, and therefore would like to do this.

    I'll keep you posted on any development.

    Best,
    Darren
  • SchenyScheny Member Posts: 5
    Thank you Darren for considering it and thanks Kevin for the hotfix!
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