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Thread: Scale Airfoil

  1. #1

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    Scale Airfoil

    I've gone ahead and made my airfoil ( NACA 23012 ) but don't know how to bring it to proper scale.

  2. #2
    cwilliamrose's Avatar
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    I'm not sure I understand. Did you use the published ordinates for the 23012? Using those you need to multiply by the chord of the wing. The chord (X in the tables below) in the published ordinates is expressed as a percentage 0-100%. The thickness (Y in the tables below) is also expressed as a percentage of the chord. I often use a spreadsheet to do the calcs and make tweaks;

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    Last edited by cwilliamrose; 06-25-2020 at 12:51 PM.

  3. #3
    cwilliamrose's Avatar
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    If your airfoil was plotted using the straight ordinates you have created an airfoil with a chord of 100(units). If the units are inches and you want a 60" chord you would scale the model to 60%. This can be done using the Insert|Features|Scale.... function in the menus. There are options for that function so make sure you understand it so you get what you need.

  4. #4
    vondeliusc's Avatar
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    Big Grin Using Curve through XYZ Points

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    rkirk77-
    Very simple: Use Excel and arrange the X coords along Z in SW and the Y coords along Y and set 0 for all the X coords.
    You can find most airfoils in this DB: https://m-selig.ae.illinois.edu/ads/coord_database.html

    • The file format must be a three-column, tab, or space-delimited list of only X, Y, and Z coordinates. Do not include any column headings, such as X, Y, and Z or other extraneous data.
      Save it as a .txt or .sldcrv file type.

    Use 0 to 1 or 0 to 100 so it should look like this-ish:
    0 0 0
    0 .25 -.1
    0 .375 -.2
    0 .4 -.3
    ...
    0 .2 -.9
    0 .1 -.95
    0 0 -1
    This will give you a nice airfoil on the right plane with the nose fwd in the +Z direction
    Your actual data from the above site:
    NACA 23012 12%
    1.00003 0.00126
    0.99730 0.00170
    0.98914 0.00302
    0.97563 0.00518
    0.95693 0.00812
    0.93324 0.01176
    0.90482 0.01602
    0.87197 0.02079
    0.83506 0.02597
    0.79449 0.03145
    0.75070 0.03712
    0.70417 0.04285
    0.65541 0.04854
    0.60496 0.05405
    0.55335 0.05924
    0.50117 0.06397
    0.44897 0.06811
    0.39733 0.07150
    0.34681 0.07402
    0.29796 0.07554
    0.25131 0.07597
    0.20738 0.07524
    0.16604 0.07320
    0.12732 0.06915
    0.09230 0.06265
    0.06203 0.05382
    0.03730 0.04324
    0.01865 0.03176
    0.00628 0.02030
    0.00015 0.00956
    0.00000 0.00000
    0.00533 -0.00792
    0.01557 -0.01401
    0.03029 -0.01870
    0.04915 -0.02248
    0.07195 -0.02586
    0.09868 -0.02922
    0.12954 -0.03282
    0.16483 -0.03660
    0.20483 -0.04016
    0.24869 -0.04283
    0.29531 -0.04446
    0.34418 -0.04510
    0.39476 -0.04482
    0.44650 -0.04371
    0.49883 -0.04188
    0.55117 -0.03945
    0.60296 -0.03655
    0.65360 -0.03327
    0.70257 -0.02975
    0.74930 -0.02607
    0.79330 -0.02235
    0.83407 -0.01866
    0.87118 -0.01512
    0.90420 -0.01180
    0.93279 -0.00880
    0.95661 -0.00621
    0.97543 -0.00410
    0.98901 -0.00254
    0.99722 -0.00158
    0.99997 -0.00126
    Which I copy/pasted to notepad and saved.
    Then imported to Excel and with a little wizardry becomes:
    x0 y z(x)
    0 0.00126 -1.00003
    0 0.0017 -0.9973
    0 0.00302 -0.98914
    0 0.00518 -0.97563
    0 0.00812 -0.95693
    0 0.01176 -0.93324
    0 0.01602 -0.90482
    0 0.02079 -0.87197
    0 0.02597 -0.83506
    0 0.03145 -0.79449
    0 0.03712 -0.7507
    0 0.04285 -0.70417
    0 0.04854 -0.65541
    0 0.05405 -0.60496
    0 0.05924 -0.55335
    0 0.06397 -0.50117
    0 0.06811 -0.44897
    0 0.0715 -0.39733
    0 0.07402 -0.34681
    0 0.07554 -0.29796
    0 0.07597 -0.25131
    0 0.07524 -0.20738
    0 0.0732 -0.16604
    0 0.06915 -0.12732
    0 0.06265 -0.0923
    0 0.05382 -0.06203
    0 0.04324 -0.0373
    0 0.03176 -0.01865
    0 0.0203 -0.00628
    0 0.00956 -0.00015
    0 0 0
    0 -0.00792 -0.00533
    0 -0.01401 -0.01557
    0 -0.0187 -0.03029
    0 -0.02248 -0.04915
    0 -0.02586 -0.07195
    0 -0.02922 -0.09868
    0 -0.03282 -0.12954
    0 -0.0366 -0.16483
    0 -0.04016 -0.20483
    0 -0.04283 -0.24869
    0 -0.04446 -0.29531
    0 -0.0451 -0.34418
    0 -0.04482 -0.39476
    0 -0.04371 -0.4465
    0 -0.04188 -0.49883
    0 -0.03945 -0.55117
    0 -0.03655 -0.60296
    0 -0.03327 -0.6536
    0 -0.02975 -0.70257
    0 -0.02607 -0.7493
    0 -0.02235 -0.7933
    0 -0.01866 -0.83407
    0 -0.01512 -0.87118
    0 -0.0118 -0.9042
    0 -0.0088 -0.93279
    0 -0.00621 -0.95661
    0 -0.0041 -0.97543
    0 -0.00254 -0.98901
    0 -0.00158 -0.99722
    0 -0.00126 -0.99997
    Copy paste into notepad and lose the header.
    Use the 'Curve through XYZ Points' tool.
    Browse for your NACA 23012.sldcrv file you saved from notepad.
    Import and you get a nice spline.
    Insert a sketch on the R plane and project the imported spline.
    Cap with a nice line at the tail.
    Now it is 1" long; either scale the sketch or extrude it .1" to a solid,
    and then scale the solid.
    You can do a root version chord length and a tip version chord length, and
    even introduce washout (twist) and then loft for a complex wing including sweep.
    Easy peasy.
    '-)
    -Christian

    Name:  naca sldcrv raw.jpg
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    Name:  naca projected sketch.jpg
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    Name:  naca extruded (1'' chord).jpg
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    Part and data files:
    NACA 23012 data & part.zip

  5. #5
    vondeliusc's Avatar
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    Here is half the 30' span wing with 15 degree sweep, 3 degrees dihedral, and 1.5 degrees washout, 66" root & 22.25" tip.
    If you study the assembly, you will see how I did it; tip: study the skeleton: you can change parameters and the model will update.
    https://drive.google.com/file/d/19_C...ew?usp=sharing
    Pack N'Go Assy ^^
    -Christian
    Last edited by vondeliusc; 06-25-2020 at 11:51 AM.

  6. #6
    FlyingRon's Avatar
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    You do understand about Reynolds numbers?

  7. #7

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    I would like to enter into solidworks a rib shape using the XYZ curve tool...ive included the rib shape with dimensions....does the above information apply to this also...Ive tried to enter the dimensions into solidworks manually but I get modern art and not a rib shape...so I~m doing something wrong...is there a good write up on this xyz tool to understand it better. I`m a little baffled how the xyz numbers relate..

    Thanks
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    Last edited by North_roll; 06-25-2020 at 07:27 PM.

  8. #8
    vondeliusc's Avatar
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    Lightbulb Using Curve through XYZ Points

    North_roll(real name would be nice)-
    Normally airfoil data is in terms of 0 to 1 from nose to tail, with the Yu(pper) and Yl(ower) either given as shown,
    or with Y +/-.
    SolidWorks' convention in general is that [+X is left], [+Y is up], and [+Z if fwd].
    So if you look normal to the right plane from the left, the origin is zero, with -Z going right, and +Y is above the Z axis
    and -Y is below.
    If you specify the nose of the airfoil at Z=0, the TE will be at Z=-1
    The Curve through XYZ are cartesian coords with the above SW convention.

    Using the tool to draw an airfoil, you specify the Upper TE coord, progressing along the upper camber forward.
    In other words: (set X to zero for all coords and disregard)
    For the airfoil coordinate pairs: Z starts at -1 and and the corresponding Y values increase from near zero to max upper camber and then Y values decrease to 0 as Z approaches 0 at the nose,
    where normally Z and Y=0.
    Continuing on around below the nose, Z again moves back toward the tail increasing(?-decreasing) to -1 again,
    while Y increases in the negative with a maximum value a maximum lower camber until it approaches near 0 again.
    A careful reading (many times?) of the above description and you should understand.

    So converting the numbers from the ZA plans, the SW coords are as follows:
    (You could imagine those numbers as X,Y on a standard graph from the parentheses),
    but they have to be in the order they are below for the Curve thru XYZ to lay on the R Plane.
    Also, since your AF is not '1' long, you will start at Z=0 for the front rib rear and end at Z=499 for the front.
    In the case of your numbers, assume 499 = '1' for Z

    Your Fwd rib becomes:
    X Y(vert) Z(horz)
    0 -90 0
    0 -89.5 100
    0 -86 200
    0 -77 300
    0 -71 350
    0 -61.8 400
    0 -56 425
    0 -49 450
    0 0 499
    0 49 475
    0 71.5 450
    0 87.7 425
    0 100 400
    0 119 350
    0 131.2 300
    0 144 200
    0 147 100
    0 148.5 0

    Study how the numbers are translated from the plans chart.
    After the curve is generated, you must 'project' it on a sketch on the R plane.
    For the rear rib:
    X= all zero
    Plans X=SW Z
    Plans Y=SW Y, with upper = positive
    and lower = negative
    It takes about 1 minute to enter into Excel, but since it is not continuous, you MUST do a separate sldcrv for each curve.
    (Don't forget to use a metric template in SW)
    So:
    Normal X,Y Y X Y X
    SW Y,Z Y Z Y Z
    0 148.5 0 0 -90 0
    0 145 -100 0 -89.3 -100
    0 137.5 -200 0 -84 -200
    0 127 -300 0 -74 -300
    0 114 -400 0 -30 -622
    0 96.5 -500
    0 77 -600
    0 72 -622

    The section specified as straight appears negligible to me compared to the SW spline.
    The SW file is available for study here: https://drive.google.com/file/d/1BG3...ew?usp=sharing
    You must pay attention to the operation of whether the numbers are positive or negative.
    -Christian

  9. #9

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    Thank you for taking the time to explain this ...really demystified it for me....

    I'll start playing with numbers using the information you gave me and in the post above you did for the other member..


    Thanks
    Michael

  10. #10

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    I think I am having some difficulty with getting the airfoil to scale down so the airfoil has a 63" chord (..or 63% from what i am reading here).

    I am trying to make it so I can make a layout for making new ribs for my project and want to be able to mark out where the spars and stringers will be positioned.
    I am new to Solidworks, so it's sometimes hard to understand what to do.
    Last edited by rkirk77; 08-16-2020 at 04:45 PM.

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