Book 15, Question 103
Why Do Two of a Drone's Propellers Spin One Way and Two the Other?
Two propellers spin one way and two spin the other so the drone stays pointing straight! Every spinning propeller gives the drone body a small twist in the opposite direction. Spinning in pairs makes those twists cancel out.
More fun facts
- Spinning propellers push back on whatever is spinning them, in the opposite direction.
- Scientists explain this with Newton's third law.
- Most helicopters use a small tail rotor to fight this twisting force, or they would spin out of control.
- Some helicopters instead stack two rotors spinning in opposite directions.
- When propellers spin in opposite directions, their twisting pushes cancel each other out.
Sources: Smithsonian, Exploratorium
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