Updated by Bill Lofton 5/10/16
Courtesy of e-volo, e-volo, gasturbine101 on YouTube
Multicopter flight isn’t possible without fly-by-wire (FBW) flight control. Not possible. Multicopters don’t have ailerons, elevators, or rudder to control aircraft attitude while the fans pull the aircraft through the sky. What multicopters do have is 4+ propellers, half of them turning CW and the other half turning CCW, and each powered independently.
Without help of electronic flight control, an RC multicopter operator would have an RC transmitter with 4+ throttle sticks, one for each propeller. The operator would try (and fail) to control aircraft attitude using differential thrust commands, i.e. different throttle inputs at each of the 4+ throttle sticks. Good luck with that.
Evolution of Flight Control Systems
Intro to RC Multicopter Flight Control, Autopilots, and Autonomous Flight
Scaling Up RC Multicopter Flight Control to Manned Multicopters
RC Multicopter Flight Control
Off-The-Shelf RC Multicopter Flight Controllers/Autopilots
Multicopters With Undisclosed Flight Controllers/Autopilots