Motor calculation
Up Instructions Motordata

 

Calculate the right motor - propeller combination

An explanation on how to use this page can be found here


Enter the specifications of the model

Name of the plane
mm Specify span
dm2 Specify wing area
g Specify weight
Specify a shape factor
m/s Specify the required climb
Recommended maximum wing loading for a combustion motor model g/dm2
Recommended maximum wing loading for a electric motor model g/dm2
Wing loading for configuration specified g/dm2
Minimum sink rate m/s
Watts required for level flight W
Watts required for requested climb W
Minimum watts based on 100W per kg rule W
Maximum Watts required for take-off W
Watts required for adjustment of 1 m/s W
W With this power the further calculations will be done
Prop diameter (Minimum) inch
Prop diameter (Recommended) inch
inch With this propeller diameter the further calculations will be done
Prop pitch (Minimum) 50% of diameter used for a dragger inch
Prop pitch (Recommended) inch
Prop pitch (Maximum) 90% of diameter used for a hotliner inch
inch With this propeller pitch the further calculations will be done


Enter the specifications of the motor

Name of the motor
Ohms Specify Ri
A Specify Iopen
RPM/V Specify Kv
Specify Pri (Maximum motor load)
gram Specify weight of the motor
A Requested nominal motor Amps
Calculated number of cells
With this number of cells the further calculations will be done
Stall speed km/h
Maximum speed (stall speed *3) km/h
Rm required (WS figure out next formula!!) Ohms
Output power W
Prop RPM RPM
Motor RPM RPM
Gear ratio


Select the proper gear ratio

With this selected gear ratio the further calculations will be done


Based on the selected values the model will have the following performance

Corrected real prop RPM RPM
Calculated real maximum model speed km/h
Calculated output power, corrected for selected prop W
Motor efficiency. Some work to do to find out how to calculate at this stage
Real current A
Motor losses W
Maximum motor current A
Maximum Power W
Input Power W
Output Power W
Efficiency calculated %
Copper Losses W
Iron Losses W
Current for maximum efficiency of motor A