A rotor assembly for a rotorcraft, the rotor assembly comprising: a rotor hub, comprising rotor-blade supports; and rotor-blade assemblies, each coupled to a respective one of the rotor-blade supports; wherein: the rotor hub has a rotation axis about which the rotor hub has a rotational symmetry of order N; the rotor-blade supports are N in number; and each of the rotor-blade assemblies comprises: a flap axle, extending through a respective one of the rotor-blade supports and having a central flap-axle axis; a hub connector, coupled to a respective one of the rotor-blade supports via the flap axle, pivotable relative to a respective one of the rotor-blade supports about the central flap-axle axis, and defining a central hub-connector axis that is perpendicular to the central flap-axle axis; a rotor blade, coupled to the hub connector, pivotable relative to the hub connector about the central hub-connector axis, and, together with the hub connector, pivotable relative to a respective one of the rotor-blade supports about the central flap-axle axis; and a torsion strap, having a first end, coupled to the rotor blade, and a second end, through which the flap axle passes. a rotor hub, comprising rotor-blade supports; and rotor-blade assemblies, each coupled to a respective one of the rotor-blade supports; wherein: the rotor hub has a rotation axis about which the rotor hub has a rotational symmetry of order N; the rotor-blade supports are N in number; and each of the rotor-blade assemblies comprises: a flap axle, extending through a respective one of the rotor-blade supports and having a central flap-axle axis; a hub connector, coupled to a respective one of the rotor-blade supports via the flap axle, pivotable relative to a respective one of the rotor-blade supports about the central flap-axle axis, and defining a central hub-connector axis that is perpendicular to the central flap-axle axis; a rotor blade, coupled to the hub connector, pivotable relative to the hub connector about the central hub-connector axis, and, together with the hub connector, pivotable relative to a respective one of the rotor-blade supports about the central flap-axle axis; and a torsion strap, having a first end, coupled to the rotor blade, and a second end, through which the flap axle passes. the rotor hub has a rotation axis about which the rotor hub has a rotational symmetry of order N; the rotor-blade supports are N in number; and each of the rotor-blade assemblies comprises: a flap axle, extending through a respective one of the rotor-blade supports and having a central flap-axle axis; a hub connector, coupled to a respective one of the rotor-blade supports via the flap axle, pivotable relative to a respective one of the rotor-blade supports about the central flap-axle axis, and defining a central hub-connector axis that is perpendicular to the central flap-axle axis; a rotor blade, coupled to the hub connector, pivotable relative to the hub connector about the central hub-connector axis, and, together with the hub connector, pivotable relative to a respective one of the rotor-blade supports about the central flap-axle axis; and a torsion strap, having a first end, coupled to the rotor blade, and a second end, through which the flap axle passes. a flap axle, extending through a respective one of the rotor-blade supports and having a central flap-axle axis; a hub connector, coupled to a respective one of the rotor-blade supports via the flap axle, pivotable relative to a respective one of the rotor-blade supports about the central flap-axle axis, and defining a central hub-connector axis that is perpendicular to the central flap-axle axis; a rotor blade, coupled to the hub connector, pivotable relative to the hub connector about the central hub-connector axis, and, together with the hub connector, pivotable relative to a respective one of the rotor-blade supports about the central flap-axle axis; and a torsion strap, having a first end, coupled to the rotor blade, and a second end, through which the flap axle passes.