Here a video of a long duration LOITER (GPS position Hold) with my QRO quadcopter piloted by the ArduMega v2 board and the firmware ArduCopter v2.2 B4xp1 (with JLN mod). The flight is very stable and secure.
Avionic setup: ArduPilot Mega v2, firmware Arducopter V2.2 B4xp1
Receiver: Turnigy 9X8C v2, Transmitter: Turnigy 9x, c 5V @ 5A Turnigy
Quacopter frame: DJI Flame Wheel F450
Hardware Setup: 4 brushless motors RC Timer BC-2836/11 (750 KV), 2 CW propellers 12 x 4.5, 2 CCW propellers 12 x 4.5, 4 ESC 40A RC Timer speed controllers, one Lipo battery 3S Turnigy Nano-Tech 2200 mAh
Take Off Weight (TOW): 1088 g without payload, Flight time: about 10 min
More infos at:http://diydrones.com/profile/JeanLouisNaudin