A rotor assembly, comprising: a rotor mast configured to be driven in rotation about a mast axis; a rotor hub coupled to the rotor mast for common rotation therewith about the mast axis; a plurality of rotor blade assemblies coupled to the rotor hub for common rotation therewith about the mast axis, each rotor blade assembly being rotatable relative to the rotor hub about a pitch-change axis; a control tube extending through the rotor mast wherein a top portion extends above the rotor mast and a bottom portion extends below the rotor mast, the control tube being translatable relative to the rotor mast along the mast axis; a crosshead coupled to the control tube, the crosshead being configured to cooperatively engage the plurality of rotor blade assemblies, wherein translation of the crosshead along the mast axis causes rotation of the plurality of rotor blade assemblies about their pitch-change axes; and a mechanism configured to drive the rotor mast in rotation; wherein the mechanism comprises an electric motor; and wherein the rotor assembly further comprises a fan disposed between the rotor hub and the electric motor; and wherein the mechanism and the fan are longitudinally positioned between the top portion and the bottom portion of the control tube and coaxially with the mast axis; wherein while the crosshead is installed, the crosshead is prevented from angular rotation about the mast axis; and wherein a pin of a rotor blade assembly is captured between opposing tabs (196, 198) of the crosshead and movable relative to the opposing tabs (196, 198) in response to translation of the crosshead along the mast axis. a rotor mast configured to be driven in rotation about a mast axis; a rotor hub coupled to the rotor mast for common rotation therewith about the mast axis; a plurality of rotor blade assemblies coupled to the rotor hub for common rotation therewith about the mast axis, each rotor blade assembly being rotatable relative to the rotor hub about a pitch-change axis; a control tube extending through the rotor mast wherein a top portion extends above the rotor mast and a bottom portion extends below the rotor mast, the control tube being translatable relative to the rotor mast along the mast axis; a crosshead coupled to the control tube, the crosshead being configured to cooperatively engage the plurality of rotor blade assemblies, wherein translation of the crosshead along the mast axis causes rotation of the plurality of rotor blade assemblies about their pitch-change axes; and a mechanism configured to drive the rotor mast in rotation; wherein the mechanism comprises an electric motor; and wherein the rotor assembly further comprises a fan disposed between the rotor hub and the electric motor; and wherein the mechanism and the fan are longitudinally positioned between the top portion and the bottom portion of the control tube and coaxially with the mast axis; wherein the mechanism comprises an electric motor; and wherein the rotor assembly further comprises a fan disposed between the rotor hub and the electric motor; and wherein the mechanism and the fan are longitudinally positioned between the top portion and the bottom portion of the control tube and coaxially with the mast axis; wherein while the crosshead is installed, the crosshead is prevented from angular rotation about the mast axis; and wherein a pin of a rotor blade assembly is captured between opposing tabs (196, 198) of the crosshead and movable relative to the opposing tabs (196, 198) in response to translation of the crosshead along the mast axis.