Propellers

Pushing air down

The propellers start to spin. The white dots are air being pushed down. When a propeller pushes air down, the air pushes the propeller up just as hard. The blue arrows show that push. It is still smaller than the weight, so the drone stays on the ground.

Why?It is like swimming. Push water backward, and the water pushes you forward. Whenever you push something, it pushes you back the same amount in the opposite direction. A propeller pushes air down, and the air pushes the propeller up.

Go furtherEach blade is a small airplane wing. Tilted blades whirl around and throw air downward. To see how an airplane wing lifts, watch another seeplore story about a 250-ton airliner. The rule that every push gets a push back is Newton’s third law.