Originally Posted by
howardcano
The torque and power curves for the Orion look pretty gnarly above 15000 RPM, so I wouldn't draw any conclusions from the data. It definitely looks like the MD2 isn't nearly accurate enough up there. And the flat top on the power curve for file1 says it isn't accurate enough at lower speeds, either. Or are these artifacts from other processing of the data?
Sample rate is only 50hz so a lot can happen in .02 sec when the motor acceleration is high at the start. I do some linear averaging on the recorded data to help smooth out the results so sometimes you get a flat top. I normally do three consecutive runs to make sure the results are consistent. As I said earlier higher sample rates or slowing the acceleration by using a larger flywheel would help the MD2 but not solve everything. The MD2 is far from perfect but then what can you expect for $150.
I am still planning to get some larger flywheels made which will increase the number of samples at lower RPM and should help improve the accuracy. I look forward to seeing your results with the high sample rate. Should make for some interesting comparisons. If you share some data with me I'll process it through RC3 for you to compare with your torque and power calcs.
Are you measuring RPM directly off the motor terminals or using an external encoder or hall effect sensor?