4 Replies Latest reply on Mar 17, 2014 9:10 PM by J. Mather

    Curve through XYZ not specific enough

    Steven Trvalik

      I am attempting to create a NACA 2412 airfoil using the coordinates given by the generation found here. I have added in the Z coordinates=0 (as well as the stuff at the top) however the function in Solidworks is not specific enough to plot all of the points. Plot a curve through XYZ points will automatically shorten the points to the hundredths place. The problem with this is that the majority of the points for the airfoil are only different from the thousandths place on.

       

      Is there any way I can force Solidworks to recognize all of the digits?

       

      Thanks!

        • Re: Curve through XYZ not specific enough
          Jan Forkovic

          Hi

          Even if you do not see any decimal places, Solidworks uses them. Try to set the Document Properties-Units to more decimal places and you will see them

          Clipboard02.jpg

          • Re: Curve through XYZ not specific enough
            Rick McWilliams

            It will use all of the digits. The spline approximation is very weird. Turn on curvature combs to see the crazy wiggles. Airfoils are sensitive to curvature and rate of change of curvature. I get the best results using le, te and two or three points in between. Then draw a spline that snaps to these points and adjust curvature combs manually.  Alternatively you can use geometric formula for NACA four digit airfoils.

            • Re: Curve through XYZ not specific enough
              George Smith

              Steve,

               

              Adjust your decimal settings to five or six places in "document properties" for the file containing the curve.  The "curve file" dialog displays the coordinates according to this setting.

               

              Also, I have imported this same data file and the trailing edge of the foil is open as reflected in the first line"Y" (0.001260 ) point for the upper surface and the last line "Y" (-0.001260 ) point for the lower surface. Select the "close trailing edge" check box for the adjusted data points.

              • Re: Curve through XYZ not specific enough
                J. Mather

                Steven Trvalik wrote:

                 

                ...The problem with this is that the majority of the points for the airfoil are only different from the thousandths place on.

                 

                Thanks!

                What is the precision of your manufacturing system?

                Just because you (or your computer) can calculate out to x number of digits - doesn't make them significant.