The simplest approach I have seen to figuring power systems in electrics is
input watts per pound of "all up" airplane weight. The following guidelines
were developed before brushless motors were common but it seems to hold
pretty well so we will use it regardless of what kind of motor is being
50 watts per pound = Casual/scale flying
75 watts per pound = Sport flying and sport aerobatics
100 watts per pound = aggressive aerobatics and perhaps mild 3D
150 watts per pound = all out performance.
Remember that Watts = Volts X Amps. This is a power measurement.
In case you were wondering, 746 watts equals 1 horsepower.