Figure 1. AirFreeCAD
1. WHAT IS AirFreeCAD?

This utility is an small python program 'macro', that reads an airfoil file, either in .txt Laboratori format, or in a standard format .txt, .dat, or .pfl, and automatically draws the airfoil in a FreeCAD document. Then the airfoil can be studied and exported to other formats such as dxf, svg, and others.

In the case of the airfoils used by the Laboratori, the drawing shows all the information contained in the header. Draw the airfoil in three parts: upper surface, vents, and lower surface. The counting of points is made, and the position of the vents show in % of the chord.

This is not something extraordinary, but a demonstrator of the great utility of FreeCAD, and the possibilities that are open to make more interesting studies. Theoretically, it would be possible to make a macro for each section of LEparagliding, and integrate it all into a new FreeCAD workbench... So it would be possible to integrate LEparagliding in FreeCAD! This is now just a dream...! And remember that an specific graphical interface is currently being developed.

2. FreeCAD

FreeCAD is a 3D CAD/CAE parametric modeling application. It is primarily made for mechanical design, but also serves all other uses where you need to model 3D objects with precision and control over modeling history. It is not a simple program to use, but has many possibilities. Is in active development and gradually are being added many utilities in different fields of engineering. In my opinion it is a masterpiece of free software. Available for all operating systems. https://www.freecadweb.org/


a) .txt, .dat, .pfl, standard format. Example gnua.dat

Are text files with the following format:

line 1: Airfoil name
line 2 and following: x_coordinate   y_coordinate

The coordinates begin at the point (1.0,0.0) which is the trailing edge, continues by the upper surface up the nose  (0.0,0.0), and then by the bottom surface up to get again in the point (0,0). Defines an airfoil with chord size one unit.

Figure 2. gnua.dat

b) .txt Laboratori format. Example gnua.txt

line 1: AIrfoil name
line 2: Total number of points
line 3: Points number from trailing edge to vent init
line 4: Points number in the vents from init to fin
line 5: Points number from vent fin to trailing edge
line 6 and following: x_coordinate   y_coordinate (exactly as in standard format)

We are assuming that the separator of decimal point is "." not ",". Change if necessary.

Figure 3. gnua.txt


- Install FreeCAD-0.18.4 or newer
- Install Python3 and related packages
- Start FreeCAD
- Open a new document
- Select the 'Draft' workbench
- Go to menu 'Macro' and execute the AirFreeCAD.FCMacro, that previously must be copied inside the directory .FreeCAD/Macro
- Using the dialog, select your .txt, .dat, or .pfl airfoil
- View and analize the results
- Run again the macro selecting another airfoil

Macro for FreeCAD
Airfoil in .txt Laboratori format
Airfoil in standard .txt format
Airfoil in standard .dat format
Airfoil in standard .pfl format
All files in one .zip