Variable pitch quadrocopter flies upside down

http://hackaday.com/2012/02/24/variable-pitch-quadrocopter-flies-upside-down/

/ variable pitch quadrocopter flies upside down Aerospace Controls Laboratory /

E-volo all-electric, manned copter makes first flight (video)

http://www.greenpacks.org/2011/11/04/e-volo-all-electric-manned-copter-makes-first-flight-video/