07. Motors / Speed Controllers

Motors SpeedControllers

More on motors

Quadrotor motors typically come with various specifications describing how the motor performs and it's important to understand what these specs mean when choosing motors for your quad.

The most important thing to know about a particular motor is its so called "Kv" rating. Kv is not some standard physical unit, but rather, describes the RPMs that a motor will achieve (under zero load) when a given voltage is applied. So, in other words, Kv = RPMs / volts, and a motor that can do 4000 RPMs when 2 volts are applied gets a Kv rating of 2000.

Motors Kv

Suppose your power supply has an operating range between 3-7 volts and to generate the appropriate amount of thrust for your quad (given its weight, propeller size etc.) you need to achieve 15,000 RPMs when you're comfortably in the middle of the power supply's operating range. What's a good KV value for your motors?
SOLUTION: 3000

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