After wander around on open source host such as Sourceforge i have found out some quite interesting open source fly sim that not been develop much recently.They are:
Palomino Flight Simulator http://www.palomino3d.org/
Combat Simulator Project http://sourceforge.net/projects/csp/ or at http://sourceforge.net/apps/mediawiki/c ... =Main_Page
Thunder and Lighting http://tnlgame.net/
GL-117 http://www.heptargon.de/gl-117/gl-117.html
Flying Guns http://www.flyingguns.com/
And Aeron http://aeron.sourceforge.net/
Both are focus in aircombat and because they are all open i wonder if we could use or consult some of their feature.