Gentlenav forums

ardupilot
https://groups.google.com/forum/#!topic/drones-discuss/jpjOopE8cb0 Developer forum Andrew Tridgell, lead developer on diydrones.com using the math insight from Premelani

http://ardupilot.com/forum/

Matrix pilot - gentlenav
https://groups.google.com/forum/#!forum/uavdevboard-dev

https://groups.google.com/forum/#!forum/uavdevboard

Tridgell
http://uav.tridgell.net