ETP 104 Sound Frequency and Intensity of Propeller and Motor


1.1 To characterize the sound frequency and sound intensity output of both a motor and motor/propeller pair


2.1 Materials:
2.1.1 Motor & mounting plate
2.1.2 Propeller & prop adapters
2.1.3 Electronic speed controller (ESC)
2.1.4 Power supply
2.1.5 Force gauge with some offset mechanism
2.1.6 Tachometer High-reflective tape
2.1.7 Measuring tape
2.1.8 Smartphone with: Frequency measuring app Sound Intensity measuring app
2.2 Do not place propeller on motor yet, in case removal is difficult.
2.3 Assemble the motor and place it on force gauge with offset.
2.3.1 The offset prevents thrust data from being corrupted with unexpected aerodynamics effects
2.4 Connect all elements of test together and tune the power supply to the correct voltage (7.4 V in example photos)
2.5 Ensure motor is turning such that propeller you have chosen can be placed upside-down and have the thrust pointing down


3.1 Open both frequency measurement and intensity measurement apps on phone.
3.2 Place phone a set distance from motor (Ex: 20 cm).
3.3 Begin test, taking the following measurements:
3.3.1 Throttle value
3.3.2 Volts
3.3.3 Amps
3.3.4 RPM
3.3.5 Frequency
3.3.6 Intensity
3.4 Stop the test, turn off the power supply, and affix the propeller to the motor.
3.5 Rerun the test, now finding:
3.5.1 Throttle Value
3.5.2 Thrust
3.5.3 Volts
3.5.4 Amps
3.5.5 RPM
3.5.6 Frequency
3.5.7 Intensity