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Thread: Modeling Skylite Fuselage?

  1. #1

    Modeling Skylite Fuselage?

    Hello All,

    This is my first post here and I am modeling up a fuselage in Solidworks 2017. I recently Acquired the rights to the Raceair Skylite and Lil Bitts and want to model the Skylite up for a possible offering of a Kit or sub components. I am also a member of Chapter 40 at KWHP in Los Angeles CA.

    Anyhow, I have seen a few posts here of fuselages being done and I have a few questions. I have most of the tubing in place as a Weldment, but my question is how do I incorporate other items into this weldment that are still welded but I need/want to draw them up in the sheet metal module? Only way I can see it happening is I draw as much as I can with the weldment module than insert it into an assembly where I start adding the other bits. If I do this can I still trim the inserted parts in relation to the weldment? My guess is no?

    My other worry is since they are essentially a welded on item they really should be added in the weldment module as one of the items is the lower strut fittings and if I were to do FEA it should be all one continuous welded structure not an assembly. Curious how others have tackled this. The lower strut fittings are a bit complex and will be located near the blue gear leg tube

    Here is a pic of where I am so far.
    Name:  Skylite Fuselage - Tube Frame - 042618-1.jpg
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    Best regards,

    Marc Webster
    Cloudbase Engineering LLC
    www.cloudbaseengineering.com

  2. #2
    cwilliamrose's Avatar
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    On my Pitts model I did all the tubing structure as a weldment and inserted that part file into an assembly to add the fittings. No automatic trimming for those parts and I made no attempt to create perfect fits between added parts and the tubing structure -- those mostly get done by hand anyway. I highlighted some of the faces below to show what I didn't trim;

    Name:  Weldment-Assembly Example0.jpg
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    This is the weldment by itself, structure only -- even the tubular fairleads aren't modeled here.

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    Name:  Weldment-Assembly Example2.JPG
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    Last edited by cwilliamrose; 04-26-2018 at 09:20 AM.

  3. #3
    Thanks so much for your great reply. You pretty much confirmed what I thought. Draw as much as I can using the weldment module and anything that deviates from that even if welded on is added in an upper level assembly CAD file. The only downside to this is some of these items would also affect the nearby tubes and I wanted to have these cut at VR3 Engineering as a tube kit. So with that said, I will have a tubing kit about 90% coped with a few items that will need hand adjusting to work with the items I added in the assembly. I might still be able to use cutting planes and such but that may not be worth the added effort.

    I see you drew up a Pitts. I also bought the rights to the Lil Bitts and its sort of a mini pitts and I will tackle that fuselage next in Solidworks with a few mods to replace the unsprung gear and add a grove type spring gear.

    Best regards,

    Marc
    Cloudbase Engineering LLC
    http://www.cloudbaseengineering.com

    Gopro Camera Mounts for Aircraft.

  4. #4
    cwilliamrose's Avatar
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    You can use the JOIN feature to add parts to the structure after first creating them separately but getting a realistic result may be difficult. My lower rear wing fitting would have a weld bead added where there was contact or even close proximity between parts and there are places where the sheet metal fitting would be heated and tapped around the tubes prior to welding. Modeling all that could be very time consuming. I have not done FEA on weldments but I can imagine the amount of time it would take to get a solution.

    Name:  Weldment-Assembly Example7.JPG
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    Name:  Weldment-Assembly Example9.JPG
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  5. #5
    cwilliamrose's Avatar
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    I should also mention the CAVITY feature which you can use to 'trim' one part with another in an assembly. I believe this is the same functionality that the weldment process uses.

  6. #6
    Quote Originally Posted by cwilliamrose View Post
    You can use the JOIN feature to add parts to the structure after first creating them separately but getting a realistic result may be difficult. My lower rear wing fitting would have a weld bead added where there was contact or even close proximity between parts and there are places where the sheet metal fitting would be heated and tapped around the tubes prior to welding. Modeling all that could be very time consuming. I have not done FEA on weldments but I can imagine the amount of time it would take to get a solution.

    Name:  Weldment-Assembly Example7.JPG
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    Name:  Weldment-Assembly Example8.JPG
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    Name:  Weldment-Assembly Example9.JPG
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    Yes I have a bunch of items that mention heat up and bend to touch the smaller tube on the other side and for that it would not be fun to model and trim on a tube at an off angle. I think I am going to take your advice and do as much as I can as a weldment and where I cant I just add the parts in the upper level assembly.

    Did you draw the Pitts to have a pre coped tubing kit cut? Did you draw the entire airframe.

    Marc
    Cloudbase Engineering LLC
    http://www.cloudbaseengineering.com

    Gopro Camera Mounts for Aircraft.

  7. #7
    cwilliamrose's Avatar
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    And I have a question on FEA of weldments -- How does that work given a weldment consists of a number of separate bodies? If you add a weld bead the bodies are still separate. You can COMBINE them that's that does not really simulate a weld bead. I don't have Simulation installed so I can't play with it......

  8. #8
    cwilliamrose's Avatar
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    I did an as-built model of my fuselage and then added the stuff I haven't built yet. I have the airframe modeled as much as I need to for use as a design tool. I won't be doing any FEA since I don't know what loads to apply or how to apply them.

    BTW Ed and I go way back. Congrats on the acquisition of those two designs.
    Last edited by cwilliamrose; 04-26-2018 at 12:30 PM.

  9. #9
    EAA Staff
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    Bill: I don't think I have your email. Drop me an email and I can suggest an idea on how to do the full assembly FEA.

  10. #10
    EAA Staff
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    Marc: I'm not sure if it is entirely clear in this exchange, but if you bring parts into an assembly and then sketch on that assembly, SOLIDWORKS will transfer the revisions/additions to the original parts. Things like tubular coping applied to a sheet metal part will transfer from the assembly when you save the assembly.

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