Airfoils enables you to select Airfoil Files for the propeller and for every "wing" of the aircraft. (Remember that one wing can be built from many X-Plane "wings").
Actually, the aerodynamic properties of each "wing" is defined by four airfoil files:
- Wing root at low Reynolds number
- Wing root at high Reynolds number
- Wing tip at low Reynolds number
- Wing tip at high Reynolds number
It is possible to save a bit of work by using the same airfoil file both for the low and the high Reynolds number case. X-Plane will simply use the data from that airfoil file regardless of the actual Reynolds number.
However, using airfoil files for two different Reynolds numbers will improve the accuracy of the aircraft. See Reynolds number for details.
Note: Entering two different airfoil files in the wrong sequence will not cause a warning in Plane Maker, but it will cause X-Plane to exit on the attempt of loading the aircraft.
In addition to the aerodynamic properties indicated by the two airfoil files entered, the airfoil entered under 'lo Re' will also determine the 'physical' appearance of the wing section in question. For example, if the lo Re airfoil entered for the Wing1 root is NACA 2412, which has a thickness ratio of 12%, X-Plane will depict the wing root as having a thickness that is 12% of the Wing1 root chord length.