Unmanned flying craft

An unmanned aerial vehicle comprising a plurality of rotors, the unmanned aerial vehicle comprising:

• a power generator;
• a first electrical component;
• a second electrical component;
• a main battery capable of being charged with power generated by the power generator;
• a sub-battery;
• an internal combustion engine;
• and
• a charging circuit connecting the second electrical component and the sub-battery;
• wherein the sub-battery is configured to be charged by receiving power from the second electrical component through the charging circuit, and configured to supply power to the first electrical component;
• wherein
• the power generator is driven by the internal combustion engine to generate power;
• wherein
• the first electrical component determines whether to supply the power from the main battery to the first and second electrical components according to a state of the main battery, in response to a start of the power supply from the sub-battery.