I'm not entirely sure this is appropriate for this forum but it's worth a shot...

I have propeller data ($C_T$ , $C_P$ , J , and $\eta$) and very very limited electric brushless motor data (motor diameter, shaft diameter, Kv, voltage range, max amperage) I am trying to put together a power available curve (P vs V) but I'm not exactly sure how to use the data I have to do so. How do I get shaft power from my engine data? Or what can I use?

  • $\begingroup$ So your question is about the shaft power vs the voltage? I mean the propeller data have nothing to do here, correct? If so, here is some information, but I'm not sure this is complete. $\endgroup$
    – mins
    Commented May 27, 2016 at 0:23
  • $\begingroup$ No. Power available to the aircraft verses velocity. $\endgroup$ Commented May 27, 2016 at 20:23
  • $\begingroup$ For electric motors, torque is a function of amperage and rotational speed is a function of voltage. $\endgroup$
    – Koyovis
    Commented Jun 10, 2017 at 20:15

1 Answer 1


A simple mathematical model for electric motors has very clearly been discussed here
All you need is Kv, no-load current and Voltage to calculate the shaft power, efficiencies, etc.


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