A hybrid engine (HE) is a source of power in the unmanned aerial vehicle (UAV) [1] designated for additional power supply to the multi-copter actuators, its electric motors, as well as for replenishing the charge of the onboard battery, and solving the following tasks:-supporting charge of the on-board battery between the minimum permissible and the maximum permissible levels;-switching off the internal combustion engine when the battery reaches its maximum permissible charge level (optimal value is 80% of the charge); -turning off the HE at certain stages of the mission UAV (for example, for photo or video shooting in order to reduce the noise and vibration from the internal combustion engine (ICE); -re-enabling the HE after the shooting is completed; -providing an output power of at least 350 watts. The developed model sample of the hybrid engine for the multicopter GGP-0405.001 is an electromechanical system consisting of an internal combustion engine and an electric generator connected by a transmission mechanism, as well as an onboard battery. The main source of energy for the actuators of the multicopter is the onboard accumulator battery (AB). The HE is activated before take-off of the UAV to save battery power and increase the flight duration. During the flight, the HE is switched on for periodic recharging of the battery and when the maximum required level of charge is reached, the internal combustion engines and the electric generator (EG) are switched off.