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Comment by mynameisvlad | Hacker News Reader

This comment thread is about someone adding a parachute to their drone if they lose power, so it doesn’t fall on someone.

The propellers would not be spinning, and the object would be gently gliding down.

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The start of the thread was about either losing power or losing control.

The GP dismissal of the danger of the propellors sounded suspiciously like the guy on YT who just got fined $182k by the FAA, who argued that the first offense for hitting someone in the head should be a $20 fine.

The drone’s blades would likely still be spinning during a parachute descent... albeit at lower revolutions per minute. I’d imagine drones operate like a helicopter: in the event of an engine failure, the helicopter goes into “autorotation” in which the now unpowered rotor blades move due to the air going through the blades as the helicopter descends, thus braking the fall. However, if drones have locking rotors, then in that case the blades would not be rotating during a parachute descent.

Regardless of whether the blades are locked or spinning at lower RPMs, still better than powered drones falling from the sky!

this is a reasonable hypothesis, but quadcopters don't work this way. the propellers are usually not large enough to meaningfully slow the descent of the aircraft. also, quads are not stable the way a helicopter with one large rotor is. a drone is likely to tumble when the power is cut.

Fair point. Didn’t mean to imply that the rotors would meaningfully slow descent. Just meant to say that, parachute or not, the rotors could still be moving while unpowered. It’s more of a technicality since the slow rotation of the tiny blades would probably be towards the bottom of the list of safety concerns, parachute or not.

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