An unmanned aerial vehicle (UAV) may emit masking sounds during operation of the UAV to mask other sounds generated by the UAV during operation. The UAV may be used to deliver items to a residence or other location associated with a customer. The UAV may emit sounds that mask the conventional sounds generated by the propellers and/or motors to cause the UAV to emit sounds that are pleasing to bystanders or do not annoy the bystanders. The UAV may emit sounds using speakers or other sound generating devices, such as fins, reeds, whistles, or other devices which may cause sound to be emitted from the UAV. Noise canceling algorithms may be used to cancel at least some of the conventional noise generated by operation of the UAV using inverted sounds, while additional sound may be emitted by the UAV, which may not be subject to noise cancellation.

Multiple motors may drive (rotate) a single shaft coupled to a propeller. The motors may be selected such that a first motor is capable of rotating the drive shaft in an event of a failure of a second motor coupled to the drive shaft. A one-way clutch bearing, or similar device, may interface between a motor and the drive shaft to enable free rotation of the drive shaft in an event of the motor becoming inoperable, such as the motor freezing or locking in a position due to failure caused by overheating or caused by other conditions or events. Use of the second motor may secure a position of the drive shaft which may support the propeller in radial eccentric loading.

An engine device for an unmanned flying apparatus that provides good weight balance for the flying apparatus; cancels the gyroscopic effect; and has auto rotating propellers. The engine device includes a first cylinder and a second cylinder arranged horizontally and opposed to each other, and pistons within the cylinders advance and retract in opposite directions to each other; a first crankshaft and a second crankshaft arranged in the vertical direction, driven by the first cylinder and the second cylinder, respectively, and rotate in opposite directions; a first centrifugal clutch and a second centrifugal clutch rotate in opposite directions to each other; a final drive shaft transmitting rotational force to a gear mechanism comprising orthogonal transform gears, to rotate a propeller shaft; a one-way clutch arranged between the first crankshaft, the second crankshaft and the final drive shaft, and driven by both the first crankshaft and the second crankshaft.

An engine device for an unmanned flying apparatus that provides good weight balance for the flying apparatus; cancels the gyroscopic effect; and has auto rotating propellers. The engine device includes a first cylinder and a second cylinder arranged horizontally and opposed to each other, and pistons within the cylinders advance and retract in opposite directions to each other; a first crankshaft and a second crankshaft arranged in the vertical direction, driven by the first cylinder and the second cylinder, respectively, and rotate in opposite directions; a first centrifugal clutch and a second centrifugal clutch rotate in opposite directions to each other; a final drive shaft transmitting rotational force to a gear mechanism comprising orthogonal transform gears, to rotate a propeller shaft; a one-way clutch arranged between the first crankshaft, the second crankshaft and the final drive shaft, and driven by both the first crankshaft and the second crankshaft.

An engine device for an unmanned flying apparatus that provides good weight balance for the flying apparatus; cancels the gyroscopic effect; and has auto rotating propellers.

The engine device includes a first cylinder and a second cylinder arranged horizontally and opposed to each other, and pistons within the cylinders advance and retract in opposite directions to each other; a first crankshaft and a second crankshaft arranged in the vertical direction, driven by the first cylinder and the second cylinder, respectively, and rotate in opposite directions; a first centrifugal clutch and a second centrifugal clutch rotate in opposite directions to each other; a final drive shaft transmitting rotational force to a gear mechanism comprising orthogonal transform gears, to rotate a propeller shaft; a one-way clutch arranged between the first crankshaft, the second crankshaft and the final drive shaft, and driven by both the first crankshaft and the second crankshaft.

An engine device for an unmanned flying apparatus that provides good weight balance for the flying apparatus; cancels the gyroscopic effect; and has auto rotating propellers.

The engine device includes a first cylinder and a second cylinder arranged horizontally and opposed to each other, and pistons within the cylinders advance and retract in opposite directions to each other; a first crankshaft and a second crankshaft arranged in the vertical direction, driven by the first cylinder and the second cylinder, respectively, and rotate in opposite directions; a first centrifugal clutch and a second centrifugal clutch rotate in opposite directions to each other; a final drive shaft transmitting rotational force to a gear mechanism comprising orthogonal transform gears, to rotate a propeller shaft; a one-way clutch arranged between the first crankshaft, the second crankshaft and the final drive shaft, and driven by both the first crankshaft and the second crankshaft.

A flight device in which a mechanism for transmitting power is simplified is provided. The flight device 10 includes an airframe 19, main rotors 14, an engine 30, and power transmission shafts 25. The main rotors 14 are rotated to generate drive force that causes the airframe 19 to lift. The engine 30 includes crankshafts. The power transmission shafts 25 are connected to the crankshafts. Moreover, the engine 30 rotates the main rotors 14 via the power transmission shafts 25. The power transmission shafts 25 are tilted with respect to a second direction D2.

A flight device in which a mechanism for transmitting power is simplified is provided. The flight device 10 includes an airframe 19, main rotors 14, an engine 30, and power transmission shafts 25. The main rotors 14 are rotated to generate drive force that causes the airframe 19 to lift. The engine 30 includes crankshafts. The power transmission shafts 25 are connected to the crankshafts. Moreover, the engine 30 rotates the main rotors 14 via the power transmission shafts 25. The power transmission shafts 25 are tilted with respect to a second direction D2.

The embodiments of the present invention disclose a rotor driving system, wherein at least three first actuators can drive a nonrotating lower-rotor swashplate to tilt towards a specific direction by cooperating with each other such that a rotating lower-rotor swashplate, lower tilted-arm pull rods and blade-clamp tilted arms of the lower rotor are all in motion, thereby driving first blade clamping bodies to be twisted relative to a lower rotor hub; at least three second actuators can drive a nonrotating upper-rotor swashplate towards a specific direction by cooperating with each other such that a rotating upper-rotor swashplate, upper-rotor steering rodL arms, lower upper-rotor steering rods, pull rods, upper upper-rotor steering rods, upper tilted-arm pull rods, blade-clamp tilted arms 42 of the upper rotor are all in motion, thereby driving a second blade clamping body to be twisted relative to an upper rotor hub. Thus, in the solution, the structure of a rotor driving system is simplified, thus solving the problems of a low production efficiency of the process and of inconvenient testing and maintenance.

A flapping wing driving apparatus includes at least one crank gear capstan rotatably coupled to a crank gear, the at least one crank gear capstan disposed radially offset from a center of rotation of the crank gear; a first wing capstan coupled to a first wing, the first wing capstan having a first variable-radius drive pulley portion; and a first drive linking member configured to drive the first wing capstan, the first drive linking member windably coupled between the first variable-radius drive pulley portion and one of the at least one crank gear capstan; wherein the first wing capstan is configured to non-constantly, angularly rotate responsive to a constant angular rotation of the crank gear.