Wikipedia
OpenPilot
OpenPilot was a Free software unmanned aerial vehicle project for model aircraft aimed at supporting both multi-rotor craft as well as fixed-wing aircraft. Initially founded by David Ankers, Angus Peart and Vassilis Varveropoulos in late 2009, OpenPilot was conceived as both a learning tool and to address areas the developers perceived were lacking in other small UAV platforms.
The OpenPilot open source autopilot software can be combined with hardware such as an inertial navigation system board, a main control board, a GPS receiver, and a 2.4 GHz serial communications link with the ground station.
The OpenPilot software is released under the GPL version 3 license. OpenPilot was discontinued and reinitialized as LibrePilot.