Passive rotor alignment in a free-wheeling state

A rotor assembly for aircraft, the rotor assembly comprising:

• a rotary hub configured to rotate about an axis;
• and
• a plurality of blades extending radially from the rotary hub,
• wherein at least one of the plurality of blades includes a blade alignment device,
• wherein the rotor assembly is configured to operate in a free-wheeling state when the aircraft is in forward flight,
• wherein the blade alignment device is configured to align the at least one of the plurality of blades with airflow generated when the aircraft is in forward flight in response to airflow around the blade alignment device when the rotor assembly is in the free-wheeling state,
• wherein the blade alignment device comprises a spanwise fin pivotably coupled to an airfoil surface of the at least one of the plurality of blades along a longitudinal direction,
• wherein the spanwise fin pivots along an edge substantially parallel with the longitudinal direction to project away from the airfoil surface in a deployed position when the rotor assembly is in the free-wheeling state, and pivots along the edge to lay flat with respect to the airfoil surface in a stowed position when the rotor assembly is driven in rotation.

An aircraft, comprising:

• at least one rotor assembly configured to provide lift for the aircraft, the at least one rotor assembly comprising:
• a rotary hub configured to rotate about an axis;
• and
• a plurality of blades extending radially from the rotary hub,
• wherein the at least one rotor assembly is configured to operate in a free-wheeling state when the aircraft is in forward flight,
• wherein at least one of the plurality of blades includes a blade alignment device, the blade alignment device configured to align the at least one of the plurality of blades with airflow generated when the aircraft is in forward flight in response to airflow around the blade alignment device when the rotor assembly is in the free-wheeling state,
• wherein the blade alignment device comprises a spanwise fin pivotably coupled to an airfoil surface of the at least one of the plurality of blades along a longitudinal direction,
• wherein the spanwise fin pivots along an edge substantially parallel with the longitudinal direction to project away from the airfoil surface in a deployed position when the rotor assembly is in the free-wheeling state, and pivots along the edge to lay flat with respect to the airfoil surface in a stowed position when the rotor assembly is driven in rotation.