ESC Question
06-04-2002, 12:49 PM
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ESC Question
When a generator is not connected to a load... there's practically no resistance to turning it. Add a load and it gets hard QUICK.
You can test this easilly... Connect a 12 volt lamp to the cord of your electric starter. wind a nylon cord in the "pully" section of the starter cone. Pull hard.. the light will glow. disconnect the bulb... pull. It'll pull MUCH easier.
when the motor is set up with a braking ESC... There's a resistance load, just by the resistance of the wire in the motor. If the circuit is open, as in a non-braking ESC, its like when the bulb wasn't in the srater circuit above.
The motor will spin easilly without the "brake" simply because there's no load. Might as well be on a shaft with bearings, no windings.
the increased drag of the freewheeling prop comes from a "disc effect" The turning prop is interrupting the airstream over a disc the diameter of the prop. The stopped prop is only interfereing with airflow in the area of the blades. The aerodynamic equation to explain it is pretty complicated... Better to just go ahead and believe it, because you can easilly demonstrate it with increased glide time if the prop is stopped vs freewheeling.
You can test this easilly... Connect a 12 volt lamp to the cord of your electric starter. wind a nylon cord in the "pully" section of the starter cone. Pull hard.. the light will glow. disconnect the bulb... pull. It'll pull MUCH easier.
when the motor is set up with a braking ESC... There's a resistance load, just by the resistance of the wire in the motor. If the circuit is open, as in a non-braking ESC, its like when the bulb wasn't in the srater circuit above.
The motor will spin easilly without the "brake" simply because there's no load. Might as well be on a shaft with bearings, no windings.
the increased drag of the freewheeling prop comes from a "disc effect" The turning prop is interrupting the airstream over a disc the diameter of the prop. The stopped prop is only interfereing with airflow in the area of the blades. The aerodynamic equation to explain it is pretty complicated... Better to just go ahead and believe it, because you can easilly demonstrate it with increased glide time if the prop is stopped vs freewheeling.
