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.

Dampers (100), assemblies, and methods are provided for lead-lag damping for an articulated rotor and includes a lead-lag damper (100) having a first end connector (102) configured to be coupled to a rotor hub (H), a second end connector (104) configured to be coupled to one of a plurality of rotor blades (B), and a body portion (110) coupled to the first end connector (102) and to the second end connector (104). The body portion (110) includes one or more elastomeric material layers (120) arranged in a lengthwise direction between the first end connector (102) and the second end connector (104), with each of the elastomeric material layers (120) having a substantially chevron-shaped profile in a crosswise direction.

Dampers (100), assemblies, and methods are provided for lead-lag damping for an articulated rotor and includes a lead-lag damper (100) having a first end connector (102) configured to be coupled to a rotor hub (H), a second end connector (104) configured to be coupled to one of a plurality of rotor blades (B), and a body portion (110) coupled to the first end connector (102) and to the second end connector (104). The body portion (110) includes one or more elastomeric material layers (120) arranged in a lengthwise direction between the first end connector (102) and the second end connector (104), with each of the elastomeric material layers (120) having a substantially chevron-shaped profile in a crosswise direction.

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.

Propeller assemblies, aircraft including the same, and associated methods. A propeller assembly includes a first propeller and a second propeller operatively coupled to a coupling shaft and configured to pivot with respect to one another about a propeller rotation axis. The propeller assembly additionally includes a coupling assembly operatively coupled to the first propeller and the second propeller and configured to transition between a plurality of pivotal configurations defined between and including a stowed configuration and a deployed configuration. The coupling assembly transitions from the stowed configuration toward the deployed configuration when a coupling assembly rotational velocity rises above a threshold stowed rotational velocity. In examples, an aircraft includes one or more propeller assemblies operatively coupled to a fuselage. In some examples, a method of operating a propeller assembly includes automatically transitioning a coupling assembly of the propeller assembly between a stowed configuration and a deployed configuration.

Propeller assemblies, aircraft including the same, and associated methods. A propeller assembly includes a first propeller and a second propeller operatively coupled to a coupling shaft and configured to pivot with respect to one another about a propeller rotation axis. The propeller assembly additionally includes a coupling assembly operatively coupled to the first propeller and the second propeller and configured to transition between a plurality of pivotal configurations defined between and including a stowed configuration and a deployed configuration. The coupling assembly transitions from the stowed configuration toward the deployed configuration when a coupling assembly rotational velocity rises above a threshold stowed rotational velocity. In examples, an aircraft includes one or more propeller assemblies operatively coupled to a fuselage. In some examples, a method of operating a propeller assembly includes automatically transitioning a coupling assembly of the propeller assembly between a stowed configuration and a deployed configuration.

One embodiment is a rotor system including a rotor hub comprising a plurality of extension arms for connecting rotor blades to the rotor hub; a plurality of dampers connected between a respective one of the extension arms and the rotor hub; and a fairing disposed over the rotor hub, the fairing including an inlet plenum through which air is drawn from outside the fairing into the fairing; and at least one duct for conducting the air toward the at least one of the dampers.

The ‘Air Wheel’ rotor is a variable pitch rotor with variable twist blades. The ‘Air Wheel’ rotor comprises a closed wing coupled to one or more coaxial hubs via torsional elastic blades, the blades are coupled to the closed wing in one of the following ways: rigid, elastic, or visco-elastic. There is provided a wide range of combinations of the wing relative width and coning angle typical for a lifting rotor with a thin planar wing attached to the tips of long blades, for a shrouded fan in a wide annular wing, or for an impeller in a rotating cylindrical wing. The ‘Air Wheel’ rotor combines and enhances the advantages of a rotor and a wing, it has excellent aerodynamic characteristics, and eliminates limitations of the rotor size and flight speed. The ‘Air Wheel’ rotor can be used for designing vertical take-off and landing aircraft. The “Air Wheel” rotor is universal and can function as a lifting rotor, or a wind turbine, or an aircraft propeller, or a marine propeller.