For completeness I should add; Quadrotor configurations rely on varying prop speeds to control pitch, yaw, and roll. The larger the props the more difficult it is to vary the prop speed in a timely manner. Electric motors are more weight efficient at high speeds but larger props need to be slower. You could add a gearbox but either way you are gaining weight and complexity. Plus parts start to get really expensive as you scale up and get out of hobbyists range.