Drones these days are easier than ever to pilot, but the science behind the technology often goes overlooked. That is why Rhett Allain, a Physics Professor from Southeastern Louisiana University, created a video explaining how drones fly.
How drones fly: Hover
Professor Allain used a DJI Mavic as a model to explain a drone’s flight. When a quadcopter hovers, there are two opposite rotors that spin clockwise, while the other rotors spin counterclockwise. To keep the drone stable, all the rotors are powered equally.

This snapshot was taken from Wired’s video.
How drones fly: Acceleration

The red dot is used as a point of reference
In hover mode, the quadcopter is stabilized because the rotors are all given the same amount of power, but it’s a different story when the drone starts moving. In order for the quadcopter to accelerate forward, the power in the front two rotors are decreased, while the power in the rear rotors are increased. Similarly, when the drone accelerates left, the two rotors on the left side are decreased, while the rotors on the right side are given more power.