Performance analysis and optimal sizing of electric multirotors

This paper presents an analytical framework for addressing the hovering performance of a battery–powered multirotor. The estimation of power required for flight is investigated and an analytical model is proposed to describe the rotor figure of merit as a function of few relevant blade parameters, without the need for ad hoc experiments. The model is derived after a discussion about the aerodynamics of rotating blades. The formulation in terms of Reynolds number is supported by an experimental campaign, performed on a set of commercial–of–the–shelf propellers optimized for small–scale multirotor applications. By imposing the balance between required and available power, the hovering time is predicted by an integral formulation developed for a constant–power battery discharge process. The best endurance condition is obtained in terms of optimum battery capacity and flight time. The methodology, applicable to the design phase of novel multirotor configurations, is finally validated by flight tests.