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Old Oct 10, 2012, 04:55 PM
flylowfast is offline
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Originally Posted by Plantoflap View Post
The rpm is not needed to find the efficiency, nor is the true kv because you know the Io amp draw and Rint.

E = Efficiency = Po/Pin Io=no load amps Rint= internal resistance, should include esc fet resistance since they are in series with the motor leads.

Pin=Vin* Ain Po=( Vin-(Ain*Rint)) * (Ain-Io)
E = ( ( 1- (sq root of (Io * Rint / Vin )) )^2

Amps at max power = ( Vin + (Rint*Io)) / (2*Rint)

Io increases with rpm, its a curve. when you get your new meter graph kv and Io at various rpm. Graph the calculated amps, power and efficiency too.

Thanks, but what I really need to know is how to get in real life the thrust predicted by the calculators.
Or, failing that, some ideas on where the difference comes from.
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