I have an electric plane which currently has a 10X5 2-bladed prop and I would like to go to a 3-bladed prop to improve the ground clearance. As a rule of thumb, for 2-blade props, if I want to change the dia., I first multi the pitch by the dia and try to come close to that figure with the new size prop. For 3-bladed props, I'm guessing that multiplying the pitch by the dia (as with the 2-blade configuration, then multi that product by 1.5, the increase in additional blade and then multi that result by a efficiency loss assumed to be .85. Does this make any sense and if not, does anyone have another suggestion? Thanks