The first time I downloaded Flight Gear (FG) dates back to late november 2009.
What I liked immediately of this Open Source flight simulator is the possibility to make it grow, to medel your own airport (runways and taxiways) and structures, and to share your work with other FGsimmers.
Short after having downloaded Flight Gear, I thus downloaded Blender, a powerful tool to model 3D: again Blender is an Open Source software ...
And then I begun modelling !!!