Hovering

More goes up, equal stays put

The propellers spin faster. When the total push reaches about 105% of the weight, the drone rises. Near the height it wants, it eases off. After that, the total push equals the weight exactly. So the drone floats in one spot.

Why?If the push is bigger than the weight, the drone speeds up going up. If it is smaller, the drone speeds up going down. When the two are equal, they cancel out, and the drone keeps doing what it was doing. Here that means staying still. While hovering, each propeller lifts about 200 g and spins about 14,200 times a minute (about 237 times a second).

Go furtherThe air right under a propeller rushes down at about 7.8 m per second (about 28 km/h). That number comes from the propeller’s push and its size. The white dots move 4 times slower than real air so your eyes can follow them. Floating in one spot is called hovering, and the way to work out the air speed is called momentum theory.