A vertical take-off and landing aircraft using a hybrid power system comprising: at least one rotor (460, 520, 530, 820, 1360, 1370); an engine (220, 410, 910, 1310); a generator (230, 420, 920, 1320) configured to produce electric power using power supplied by the engine; a battery (260, 320, 440, 940, 1340) configured to store the electric power produced by the generator; a motor (280, 370, 450, 950, 1350) configured to receive at least one of the electric power stored in the battery and electric power produced by the generator but not stored in the battery and provide the power to the at least one rotor (460, 520, 530, 820, 1360, 1370); and a controller (250, 430, 930, 1330) configured to select either silence mode or normal mode, and determine the amount of electric power stored in the battery and the amount of electric power not stored in the battery from the electric power supplied to the motor, based on the selected mode, wherein: in the silence mode, the controller configured to supply only the electric power stored in the battery to the motor, and control a duration of the silence mode by adjusting output power of motor, wherein, in the normal mode, the controller configured to supply electric power not stored in the battery to the motor, wherein, in the silence mode, the controller is configured to stop the generator from producing electric power, wherein the position corresponding to an orientation of a rotation axis of the at least one rotor is variable between a first position corresponding to a first orientation of the rotation axis and a second position corresponding to a second orientation of the rotation axis, and wherein the controller configured to determine required power indicating electric power supplied to the motor considering the current position of the at least one rotor, and wherein the controller configured to determine required power supplied to the motor based on the selected mode. at least one rotor (460, 520, 530, 820, 1360, 1370); an engine (220, 410, 910, 1310); a generator (230, 420, 920, 1320) configured to produce electric power using power supplied by the engine; a battery (260, 320, 440, 940, 1340) configured to store the electric power produced by the generator; a motor (280, 370, 450, 950, 1350) configured to receive at least one of the electric power stored in the battery and electric power produced by the generator but not stored in the battery and provide the power to the at least one rotor (460, 520, 530, 820, 1360, 1370); and a controller (250, 430, 930, 1330) configured to select either silence mode or normal mode, and determine the amount of electric power stored in the battery and the amount of electric power not stored in the battery from the electric power supplied to the motor, based on the selected mode, in the silence mode, the controller configured to supply only the electric power stored in the battery to the motor, and control a duration of the silence mode by adjusting output power of motor, wherein, in the normal mode, the controller configured to supply electric power not stored in the battery to the motor, wherein, in the silence mode, the controller is configured to stop the generator from producing electric power, wherein the position corresponding to an orientation of a rotation axis of the at least one rotor is variable between a first position corresponding to a first orientation of the rotation axis and a second position corresponding to a second orientation of the rotation axis, and wherein the controller configured to determine required power indicating electric power supplied to the motor considering the current position of the at least one rotor, and