So.......How Does One Design This Fin Shape in RockSim?

Discussion in 'Rocketry Electronics and Software' started by jmmome, Oct 15, 2019.

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  1. Oct 15, 2019 #1

    jmmome

    jmmome

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    Is a custom fin design importable into RockSim? If so, what software would allow me to design these crazy contours?

    I've simplified my fin design to equate to the same square inches, but as a square-shaped fin. That is "WAG"ing way too much for me.

    Any direction would be appreciated.
    Marvin The Martian Model.JPG
     
  2. Oct 15, 2019 #2

    K'Tesh

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    You go to OpenRocket and then I can help you.

    My guess is there's some kind of import fin from image. Do that, then attach it to the smallest diameter body tube it would be glued to.
     
  3. Oct 16, 2019 #3

    Buckeye

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    No image fakery needed.

    custom fin set > plan points
     
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  4. Oct 16, 2019 #4

    kalsow

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  5. Oct 16, 2019 #5

    Tobor

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    If you can get a picture of the profile of the fin shape with the fin root at the bottom edge of the image, you can use OR's import feature. K'Tesh has an excellent tutorial on the process (Here).
     
  6. Oct 16, 2019 #6

    K'Tesh

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    Mind you that's for OpenRocket...

    And it's not image fakery, if you've got an image, OpenRocket will do the work for you instead of having to type several (dozens?) of points.
     
  7. Oct 16, 2019 #7

    mikec

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  8. Oct 16, 2019 #8

    neil_w

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    It's not image fakery, it's using an image as basis for creating the plan points. For complex curvy fins it can be *much* quicker and easier (and more accurate) to just import that way.

    Also, in Rocksim you can attach the fins directly to the transitions, don't need to use phantom body tubes like in OR.
     
  9. Oct 16, 2019 #9

    GaryT

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    I designed the Shape Shifter and the Stinger both of which have curved fins, As Buckeye said you do it in the custom fin set > plan points section of RockSim. Its not easily explained, you'll just have to play with it is all.
     
  10. Oct 16, 2019 #10

    Ez2cDave

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    No matter what the Sims say, Swing Test !

    Dave F.
     
  11. Oct 16, 2019 #11

    Nytrunner

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    That's a 50 lb. rocket....
     
  12. Oct 16, 2019 #12

    jmmome

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    Thanks guys!
     
  13. Oct 16, 2019 #13

    Ez2cDave

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    Hmm . . . Know any body-builders ?

    I guess the LCO will have to say "Duck or Bleed", rather than "Heads-Up" !

    LOL !

    Dave F.
     
  14. Oct 16, 2019 #14

    PhlAsh

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    I draw it in AutoCAD, positioned at 0,0, in millimeters. Once drawn, use the DIVIDE command to place nodes about a CM apart. Using the LIST command, pick the points in order, then paste that output into WORD to clean out the command prompts and other garbage. Replace the carriage returns with whatever the delimiter is (Pipe "|", I think, I'm at work and can't open DropBox to look). Open RockSim, create a dummy custom fin with a recognizable name - save and close. Open the RKT file in a text editor (doesn't have to be Word for this step), find my fin name and paste my pointlist, overwriting the dummy pointlist. When I did LunaBug (available on RocketReviews), I split the fins into 4 pieces in order to get the openings simulated.
     
  15. Oct 16, 2019 #15

    jmmome

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    Yup- the swing test did give me a chuckle.

    Thankfully, the Kaboom Krewe did all the heavy lifting, figuratively and literally, and a few minor tweaks based on my conversation with their group's Dan Welling (vortex generators!!!) will (should) allow it to fly straight. In addition, I won't have 85 pounds of parachutes and the accompanying cannons skewing the weight distribution to one side.
     
  16. Oct 16, 2019 #16

    boatgeek

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    You can make it a little easier on yourself in AutoCAD by drawing a PLINE through the points (just turn on the object snaps for points and it's easy) and listing the PLINE. Then the x-y coordinates come out in a single list without a lot of other garbage.
     
  17. Oct 17, 2019 #17

    PhlAsh

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    When I go that route, it usually involves curves. PLINE lists only account for Vertices, Center and Radius.
     
  18. Oct 17, 2019 #18

    boatgeek

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    If you don't curve fit or spline the PLINE, it will stay as a series of straight line sections between x-y points. At least it does for me, though I'm definitely not a power CAD user.
     
  19. Oct 21, 2019 #19

    mrwalsh85

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    Actually,
    Marvin was 550 pounds loaded :D
     
  20. Oct 22, 2019 #20

    PhlAsh

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    I figure anybody here can find the endpoints of a striaght line. I was talking about stuff like this...
    [​IMG]
     

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  21. Oct 28, 2019 #21

    Nytrunner

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    I was referring to this downscale
     

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