An aircraft (100; 300; 400) comprising a rotor system, the rotor system comprising: an open rotor assembly (108; 308; 408) comprising a plurality of rotor blades (114; 314; 414) connected to a rotor mast via a yoke, wherein the rotor assembly (108; 308; 408) is tiltable relative to a wing (104; 304; 404) of the aircraft (100; 300; 400) between a first position corresponding to an airplane mode of the aircraft (100; 300; 400) and a second position corresponding to a helicopter mode of the aircraft (100; 300; 400); and a drive system for providing rotational energy to the open rotor assembly (108; 308; 408) via the rotor mast, the drive system comprising: at least one electric motor for providing rotational energy to a drive shaft; a gearbox for receiving rotational energy from the at least one electric motor via the drive shaft and providing rotational energy to the rotor mast via a rotor shaft; and an adaptor provided between the at least one electric motor and the gearbox for facilitating maintenance, wherein: a shaft spans across the adaptor to transmit torque between the at least one electric motor and the gearbox or the drive shaft is plugged directly into the gearbox through the adaptor; the adaptor comprises a first interface connected to the at least one electric motor and a second interface connected to the gearbox, such that the at least one motor and the gearbox are removably coupled to the adaptor; the adaptor is a structural member configured to support the at least one electric motor and the gearbox; and the adaptor includes a conversion spindle; wherein the drive system is rotatable relative to the wing (104; 304; 404) about a tilt axis, wherein the tilt axis is coaxial with an axis of the conversion spindle such that the drive system is rotatable relative to the wing (104; 304; 404) about the axis of the conversion spindle; and wherein the rotor shaft is coaxial with the drive shaft. an open rotor assembly (108; 308; 408) comprising a plurality of rotor blades (114; 314; 414) connected to a rotor mast via a yoke, wherein the rotor assembly (108; 308; 408) is tiltable relative to a wing (104; 304; 404) of the aircraft (100; 300; 400) between a first position corresponding to an airplane mode of the aircraft (100; 300; 400) and a second position corresponding to a helicopter mode of the aircraft (100; 300; 400); and a drive system for providing rotational energy to the open rotor assembly (108; 308; 408) via the rotor mast, the drive system comprising: at least one electric motor for providing rotational energy to a drive shaft; a gearbox for receiving rotational energy from the at least one electric motor via the drive shaft and providing rotational energy to the rotor mast via a rotor shaft; and an adaptor provided between the at least one electric motor and the gearbox for facilitating maintenance, wherein: a shaft spans across the adaptor to transmit torque between the at least one electric motor and the gearbox or the drive shaft is plugged directly into the gearbox through the adaptor; the adaptor comprises a first interface connected to the at least one electric motor and a second interface connected to the gearbox, such that the at least one motor and the gearbox are removably coupled to the adaptor; the adaptor is a structural member configured to support the at least one electric motor and the gearbox; and the adaptor includes a conversion spindle; at least one electric motor for providing rotational energy to a drive shaft; a gearbox for receiving rotational energy from the at least one electric motor via the drive shaft and providing rotational energy to the rotor mast via a rotor shaft; and an adaptor provided between the at least one electric motor and the gearbox for facilitating maintenance, wherein: a shaft spans across the adaptor to transmit torque between the at least one electric motor and the gearbox or the drive shaft is plugged directly into the gearbox through the adaptor; the adaptor comprises a first interface connected to the at least one electric motor and a second interface connected to the gearbox, such that the at least one motor and the gearbox are removably coupled to the adaptor; the adaptor is a structural member configured to support the at least one electric motor and the gearbox; and the adaptor includes a conversion spindle; a shaft spans across the adaptor to transmit torque between the at least one electric motor and the gearbox or the drive shaft is plugged directly into the gearbox through the adaptor; the adaptor comprises a first interface connected to the at least one electric motor and a second interface connected to the gearbox, such that the at least one motor and the gearbox are removably coupled to the adaptor; the adaptor is a structural member configured to support the at least one electric motor and the gearbox; and the adaptor includes a conversion spindle; wherein the drive system is rotatable relative to the wing (104; 304; 404) about a tilt axis, wherein the tilt axis is coaxial with an axis of the conversion spindle such that the drive system is rotatable relative to the wing (104; 304; 404) about the axis of the conversion spindle; and wherein the rotor shaft is coaxial with the drive shaft.