Function importAirfoil

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GNU Octave Airfoil coordinates import function[edit]

Airfoil coordinates import function in GNU Octave.

ImportAirfoil OCT.png

Source Code[edit]

Source code for this function is available at:


Provided code is tested with GNU Octave 6.4.0.


Run importAirfoil.m with the full path to document with airfoil data as only input argument. Please check provided test.

Airfoil file parsing rules[edit]

  • The file is read a line at a time starting from the top.
  • Blank lines are discarded.
  • The first line that is not discarded is the line on which function sscanf() finds two float numbers, with the first number in the range [-0.1, 1.1] and the second in the range [-1.1, 1.1].
  • All subsequent lines on which function sscanf() finds two float numbers are taken into the account.
  • If any value is greater than 1.1 all values are divided by 100 (see NACA file format).
  • If there is one change in x value gradient, flip data that is after the change of gradient (see Lednicer file format).

Airfoil file formats[edit]

  • Siegel

Lists points from the trailing edge, goes over the upper surface, then over the lower surface, to go back to the trailing edge (or in other direction, first lower and then upper surface).

  • Lednicer

Lists points on the upper surface (from leading edge to trailing edge), then points on the lower surface (from leading edge to trailing edge).

  • OpenVSP .af

Same as the Siegel format but with the additional header.

  • NACA (as in Report No. 824)

Same as the Lednicer format but multiplied by 100.


Discussion about this function is avialable at Discourse.

Author and Licensing[edit]

Author: Miloš Petrašinović <>


Department of Aerospace Engineering, Faculty of Mechanical Engineering, University of Belgrade

Distributed under the GNU General Public License v3.0 or later license.