Openrocket Scaling question (complex fins)

Discussion in 'Rocketry Electronics and Software' started by ebruce1361, Sep 17, 2019.

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  1. Sep 17, 2019 #1

    ebruce1361

    ebruce1361

    ebruce1361

    The man with the plan. And some duct tape.

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    If I download an .ork file for a given rocket with complex freeform fins and wish to upscale it (like a BT80 Luna Bug or equivalent), is there a way to get a template for the fins by themselves that I could print out or would I have to copy them into something like MS Paint and print from there? Right now, I am wanting to specifically look for BT80 scale Luna Bug fins, so if anyone wants to just send me a scaled template that would be fine, but I would like to know how to do it with Openrocket for future builds.
     
  2. Sep 17, 2019 #2

    K'Tesh

    K'Tesh

    K'Tesh

    OpenRocket Chuck Norris

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    John Boren posted the Luna Bug's fins in several scales over on FB. Here's an 8.25" Diameter Luna Bug's fins. You'll just need to scale them to the correct size.

    Now from my .ork file, you'd need to download the fins into MS Paint and manipulate them because I had to "break" the fins to get them to appear correctly.
     

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  3. Sep 17, 2019 #3

    ebruce1361

    ebruce1361

    ebruce1361

    The man with the plan. And some duct tape.

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    Thanks! I think that first file will work, and I can size it before printing it. I forgot my wife's been wanting to do a Luna Bug, so I'll just pass the VW bug project on to her!

    As for the future, I know I can just use the measurements in the fin editor to just draw them directly onto my wood, but for something complicated like the Luna Bug or anything else with curved fins, is there a way to view the fin by itself in appropriate dimensions? I suppose I could just use PrtSc and erase the rest in Paint, but I'm just curious if there's an easier way directly through Openrocket.
     
  4. Sep 17, 2019 #4

    Bruiser

    Bruiser

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    So you got the file. You can print that out at whatever size it is and then print it to the size you need by telling your printer to reduce or enlarge it

    Did you know that if you print the fins out with a laser printer you can transfer them to the wood by ironing over them?

    Also if you use a regular printer I think you can transfer them over by putting the paper on the wood and rubbing it with paint thinner? At least I think it's paint thinner that does it. Could be acetone though. Sometimes my memory isn't so good.

    -Bob
     
  5. Sep 17, 2019 #5

    ebruce1361

    ebruce1361

    ebruce1361

    The man with the plan. And some duct tape.

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    No, I was not aware of those kinds of tricks! I have an inkjet at home, so I'll try those on some scraps of balsa. Thanks!
     
  6. Sep 17, 2019 #6

    Bruiser

    Bruiser

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    Please let me know how they worked for you. I use to use them back in my R/C days but it's been a long time ago, probably 20 years. Inks and such are probably still the same though.

    For the inkjet I used the thinner/acetone trick. I put on gloves and got a cotton ball wet and went over the lines with it. The thinner soaked thru the paper and made the lines visible so they were pretty easy to follow

    -Bob
     
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  7. Sep 17, 2019 #7

    neil_w

    neil_w

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    In OR, you can scale fins in the freeform fin editor. Or, if you scale the entire rocket, the fins will come along with it. Then, if you do File -> Export/PDF, you can get actual sized PDF outlines of your fins.

    As K'Tesh says, in this particular case the fins are done in two pieces so you'd have to put those together either in a drawing program of after you cut them out of paper.

    However, those Luna Bug fins *could* be done as single fins in OR. Here's a single piece from my Quinstar model:
    upload_2019-9-17_12-3-54.png

    Looks like this in the PDF export:
    upload_2019-9-17_12-7-58.png

    Oh, and here's what the whole ridiculous thing looks like:
    upload_2019-9-17_12-6-31.png

    Note this was just an exercise in silliness, there is little or no practical value to it.
     
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  8. Sep 17, 2019 #8

    ebruce1361

    ebruce1361

    ebruce1361

    The man with the plan. And some duct tape.

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    That's what I need! I'm not that well versed in exporting files, so I never thought to try that option. On top of that, it gives me a handy inch and CM scale, so I can tell if my printer is printing it to scale properly.

    I knew there had to be a way to do this, I just needed to pick the brains of you fine folks to get to it. Thanks!
     
  9. Sep 18, 2019 #9

    K'Tesh

    K'Tesh

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    The problem with that is that if they are too complex, OR will give you error messages and won't import the shape. I anticipated that I'd see that error, and decided not to try, and just beat this by "simplifying" the fin by splitting it. I was in a hurry to get it done, as I had to get to work in a few minutes after I finished it.
     
  10. Sep 18, 2019 #10

    ebruce1361

    ebruce1361

    ebruce1361

    The man with the plan. And some duct tape.

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    That makes sense. It's no big deal for me to reassemble the pieces either in MS Paint or just taping the paper together after printing, so this will work just fine.
     

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