Methods for performing maintenance operations using unmanned aerial vehicles (UAVs). The methods are enabled by equipping a UAV with a maintenance tool capable of performing a desired maintenance operation (e.g., nondestructive inspection) on a limited-access surface of a large structure or object (e.g., a wind turbine blade). The UAV uses re-orientation of lifting means (e.g., vertical rotors) to move the maintenance tool continuously or intermittently across the surface of the structure while maintaining contact with the surface of the structure undergoing maintenance.

Methods for performing maintenance operations using unmanned aerial vehicles (UAVs). The methods are enabled by equipping a UAV with a maintenance tool capable of performing a desired maintenance operation (e.g., nondestructive inspection) on a limited-access surface of a large structure or object (e.g., a wind turbine blade). The UAV uses re-orientation of lifting means (e.g., vertical rotors) to move the maintenance tool continuously or intermittently across the surface of the structure while maintaining contact with the surface of the structure undergoing maintenance.

The present invention relates to the field of air vehicle technologies and provides an unmanned aerial vehicle (UAV), including a vehicle body and arms connected to the vehicle body. The arm is hinged to the vehicle body by using a spherical hinge portion and may be folded or unfolded relative to the vehicle body. Through the forgoing manner, the arm is connected to the vehicle body of the UAV by using the spherical hinge. The arm can be folded and unfolded smoothly without interference, which conforms to known operation habits of users, so that after the entire UAV is folded, the structure becomes more compact and easier to carry. In addition, it can be effectively avoided that the UAV is damaged due to impact in the carrying process.

The present invention relates to the field of air vehicle technologies and provides an unmanned aerial vehicle (UAV), including a vehicle body and arms connected to the vehicle body. The arm is hinged to the vehicle body by using a spherical hinge portion and may be folded or unfolded relative to the vehicle body. Through the forgoing manner, the arm is connected to the vehicle body of the UAV by using the spherical hinge. The arm can be folded and unfolded smoothly without interference, which conforms to known operation habits of users, so that after the entire UAV is folded, the structure becomes more compact and easier to carry. In addition, it can be effectively avoided that the UAV is damaged due to impact in the carrying process.

Systems and methods related to passive variable pitch propellers are described. For example, an aerial vehicle may include one or more passive variable pitch propellers, and such propellers may include one or more passively movable propeller blades having respective hinges, flexible joints, or torsionally flexible joints. Based at least in part on current flight configurations, required thrust, and/or desired advance ratios, the passively movable propeller blades may modify their coning angles and/or pitches, such that the passive variable pitch propellers may operate with improved efficiency in two or more flight configurations. For example, in a VTOL flight configuration, the passive variable pitch propellers may have increased coning angles and decreased pitches, whereas in a horizontal flight configuration, the passive variable pitch propellers may have decreased coning angles and increased pitches.

One embodiment of a vertical take-off and landing aircraft held aloft by way of one or more powered assemblies of wing type elements capable of generating aerodynamic lift by means of rotation. A main body having an integrated means for directing air impelled from an inlet, by way of one or more powered impellers, through a cavity, acting as a duct, to an outlet. At least one movable surface located in sufficient proximity to the outlet to direct expelled air in a vectored manner providing a means of affecting the motion of the aircraft.

One embodiment of a vertical take-off and landing aircraft held aloft by way of one or more powered assemblies of wing type elements capable of generating aerodynamic lift by means of rotation. A main body having an integrated means for directing air impelled from an inlet, by way of one or more powered impellers, through a cavity, acting as a duct, to an outlet. At least one movable surface located in sufficient proximity to the outlet to direct expelled air in a vectored manner providing a means of affecting the motion of the aircraft.

A rotorcraft having a rotor system including a yoke, a plurality of grip assemblies, each of which is hingedly attach a rotor blade to the yoke, a plurality of flap stops, each flap stop attached to a respective grip assembly, a channel bounded by an upper and lower retaining surfaces, and a droop ring slideably disposed in the channel of the droop limiting system. The droop ring has a body with an inner surface, an outer surface, and a first end surface between the inner surface and the outer surface. The droop ring further has a first wear element removably disposed at the first end surface and extending above the first end surface and spaces the first end surface apart from the channel. Each flap stop is arranged to contact the outer surface of the droop ring and limit a downward droop of the respective rotor blade.

An unmanned aircraft system has a vertical takeoff and landing flight mode and a forward flight mode. The unmanned aircraft system includes an airframe, a rotor assembly rotatably coupled to the airframe and a propeller rotatably coupled to the airframe. The rotor assembly including at least two rotor blades having tip jets that are operably associated with a compressed gas power system. The propeller is operably associated with an electric power system. In the vertical takeoff and landing flight mode, compressed gas from the compressed gas power system is discharged through the tip jets to rotate the rotor assembly and generate vertical lift. In the forward flight mode, the electric power system drives the propeller to generate forward thrust and autorotation of the rotor assembly generates vertical lift.

An assembly comprising a drone (1) and at least one releasable load (37) mounted on the drone, the drone comprising an on-board data processing system, the releasable load (37) comprising at least one sensor delivering a piece of information that can be used to ascertain the path of same and actuators for controlling flight control surfaces allowing it to be oriented as it falls, being linked to the drone (1) by an optical fibre (70), the load and the drone being arranged to exchange information via the optical fibre while the load is falling, the load transmitting data originating from said at least one sensor and the drone transmitting data for controlling the actuators, established taking into account that received from the load, in order to guide the load towards a predefined target.