Drones http://uavcoach.com/are-quadcopters-better-than-rc-helicopters/ http://uavcoach.com/are-quadcopters-better-than-rc-helicopters/ http://www.forbes.com/sites/quora/2013/12/23/what-makes-the-quadcopter-design-so-great-for-small-drones/#15b64871202a