Abstract The aim of the proposed investigation is to design and analyze the performance of a hybrid electric power system for multicopter and to evaluate its performance. To this, the overall power request was assumed to be satisfied in three possible ways: a battery (electric power system), a generator powered by a two-stroke internal combustion engine (thermal power system), and both battery and engine (hybrid power system). The fuel stored on board was calculated for each configuration by keeping constant the overall mass. In the hybrid case, the engine also allows the battery to be recharged during the flight with an on/off behavior of the engine. Electric mode is started when the batteries are sufficiently charged and can produce the required propulsive power. This mode goes on as long as the state of charge (SOC) is above a minimum value. When the SOC is lower than this value, the batteries let the engine be restarted by the generator. Then, the engine generates both the power for propulsion and to recharge the battery. After a sensitivity analysis, an optimization has been performed by considering different thresholds for the battery state of charge to shift from electric to recharge mode and by taking into account different values of the recharge current. The methodology was applied to two different multicopters and the proposed powertrains were simulated with a backward approach starting from experimental time histories of required electric power.