→Loading the model
Through plib, FlightGear supports many different 3D file formats, including VRML1, AC3D, DXF, MDL (from Microsoft Flight Simulator), and many others. The property /sim/model/path in the main FlightGear property tree controls what model will be loaded; it takes a string value giving the relative path of the model from FG_ROOT (the root of the base package, such as /usr/local/share/FlightGear or C:\FLIGHTGEAR\).
The easiest way to load a new model is to set the property at startup with the --prop: command
-line option; for example, to use a 3D aircraft model that you have installed in $FG_ROOT/Models/my-cessna.wrl, you could invoke FlightGear like this (under Unix-like systems):
(Note: Normally all textures used by the model must appear in the same directory. If my-cessna.wrl uses the textures cessna01.rgb and cessna02.rgb, you should also install those textures in $FG_ROOT/Models/. It is howerever possible to specify a path (relative to the model path) to specify where the textures could be found.)
When you want to set a 3D model permanently as the default for an aircraft rather than specifying it on the command line, you need to edit an aircraft settings file. In the $FG_ROOT/Aircraft/ directory there is a series of files ending in -set.xml, such as c172-set.xml, dc3-yasim-set.xml, and beech99-uiuc-set.xml. When you start FlightGear with the --aircraft option, it reads the properties from one of these files; for example