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 of the crosshead and movable relative to the opposing tabs 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 of the crosshead and movable relative to the opposing tabs in response to translation of the crosshead along the mast axis . <EOS>