Interesting. Did you have any vibration problem? Using your measurements, and assuming a cylinder, your wheel has an inertia of about 7.5*10^-4 kg.m^2.


I was wondering what is the equivalent inertia of a car. I started with a B44. I obtained 3.4*10^-2 kg m^2, or about 45 times larger than you wheel. You can see my calculation here. It is freely editable, so people can add their own cars.

I know that in theory, the result of the characterization should be the same with a small or a large wheel, but there might be small differences due to delays in the ESC. I mean, you could even use the inertia of the rotor for the characterization, but if the acceleration is too fast, the ESC might not perfectly keep up. The question is, at what point is the inertia wheel large enough so that the results of the characterization don't change anymore?

howardcano, if I understand well, you reached 50% of the speed in 4 revolution of the inertia wheel? What speed is that? If I assume 4000RPM, I obtain a torque of about 0.2Nm assuming a constant acceleration (it is not), which sound pretty reasonable.

What is the maximum axial load tolerable by the motors bearings? Lets assume that during maximum acceleration, the torque goes up to 0.5 Nm. A pinion might have a diameter of 9mm (I measured that, anybody knows the gear size used? I could get this number exactly, as I know the number of teeth). With those assumptions, the force on the shaft is 10kg during acceleration, and a bit more if we take into account the radial force due to the pressure angle. Consequently, I think it is safe to use heavier flywheel, but I would mount the flywheel so its axis of rotation is parallel to the ground.