Cutting power is more difficult to estimate. We carried out reverse engineering on existing mowers. For a knife with 4 blades of 30cm diameter, it is necessary to have an electric motor of 100W rotating at 3000t/min.
For a cutting width of 60cm, you can choose between two propellers of 30cm diameter each, or 3 propellers of 20cm diameter. In order to reduce the longitudinal dimensions, we choose three propellers of 20cm diameter.
Based on the reverse engineering data above, and applying a rule of three, we need 60W per propeller motor, making a total of 180W.
Caution: this calculation method is empirical and the necessary powers will have to be measured and validated when the prototype is built.
For example, the robot’s forward speed can be reduced if the grass is too dense: this will limit the power consumption.