Measuring angular velocity

Results

Figure 2 below shows the results that were obtained.

Figure 2: Results for measuring the propeller’s RPM

As can be seen from the results, the frequency shown by the PicoScope meter is 566 Hz, therefore the RPM of the propeller is: (566/2) * 60 = 16,980 RPM.

By using the graph to calculate the RPM it can be seen that the time taken for once complete cycle of the waveform is 1784 µs. Therefore, the frequency is 560 Hz — giving a propeller RPM of 16,800 rpm.

The slight difference between these two results shows the inherent difficulty in obtaining accurate results when making manual calculations directly from a waveform.

Credits, comments and further info

This experiment was written by S. T. Hasan of Karachi, Pakistan.

Please contact us if you have any comments about this experiment or suggestions for improvements.