Creating Airfoil Input File for PreVABS

  1. Aqib Ahmed Syed

    How does one create an input file for VABS for an airfoil? I followed the prevabs manual closely and have used the cases for the MH104 file in an assignment for a class before, however, I see no similarities in the MH104 datapoints given online and that provided in the prevabs manual. How would I be able to modify the datapoints for my specific airfoil to resemble the way they are presented for the prevabs input file?  The airfoil of interest is a NACA 4418. 

  2. Dana Frye

    You just require the normalized xy coordinates of the airfoil profile. You can scale it based on the chord length, and/or apply twist within the main input file. 

  3. Aqib Ahmed Syed

    Thank you for the response. That said, I have tried something similar to what you suggested.. only to find some issues with the numbering of points for the airfoil coordinates. As mentioned earlier, I attempted to mimic the datapoint setup given for the MH104, but this did not yield satisfactory results. Do you have a sample prevabs file you did such an analysis on that I may look at? 

  4. Su Tian

    The differences of the MH104 airfoil data between the example and the online version are:

    1. The number of data points. The example MH104 airfoil data file is provided by a developer of an older Matlab version of PreVABS. There are more points than the online version. I believe the example airfoil is generated by sampling more points on the profile using certain tools with the knowledge of the math defining the airfoil.
    2. The orders are different. The example data starts from the leading edge (0, 0) and is listed clockwise. The online version data starts from the trailing edge (1, 0) and is listed counter-clockwise.

    The second point is important. It relates with how you define the direction of base lines and skin layup.

    The example airfoil data will be changed to the online version one in future updates.