Electric tiltrotor aircraft

An aircraft comprising:

• an airframe comprising a fuselage, an empennage, a left wing, and a right wing, the left and right wings fixed to the fuselage, wherein the airframe defines a yaw axis, a pitch axis, and a roll axis, wherein said left wing and said right wing have an inner portion extending from said fuselage to a midpoint of the wing, and have an outer portion extending from said midpoint to said wing tip, wherein said inner portions of said wings extend upward along said yaw axis in a direction from the fuselage to the midpoint defining the high point of said wings, and wherein said outer portions of said wings extend downward in a direction from said midpoint to the wingtip;
• a plurality of propulsion assemblies coupled to the airframe, comprising:
• a left outboard propulsion assembly coupled to the left wing, a right outboard propulsion assembly coupled to the right wing, a left inboard propulsion assembly coupled to the left wing at the high point of the left wing between the left outboard propulsion assembly and the fuselage, a right inboard propulsion assembly coupled to the right wing at the high point of the right wing between the right outboard propulsion assembly and the fuselage, a left rear propulsion assembly coupled to a left side of the empennage, and a right rear propulsion assembly coupled to a right side of the empennage, wherein each propulsion assembly of the plurality comprises:
• an electric motor;
• a propeller coupled to the electric motor;
• and
• a tilt mechanism connecting the electric motor and the propeller to the airframe, the tilt mechanism configured to transform the propulsion assembly between a forward configuration and a hover configuration,
• wherein in the forward configuration:
• the propeller defines a disc area, a hub at a center of the disc area, and a disc plane containing the disc area, wherein the tilt mechanism pivots the propulsion assembly relative to the wing, and
• the disc plane is perpendicular to the roll axis, and
• wherein in the hover configuration:
• the disc plane is perpendicular to the yaw axis;
• wherein the aircraft is configurable between a forward arrangement and a hover arrangement in which each of the plurality of propulsion assemblies is arranged in the forward configuration and the hover configuration, respectively;
• wherein in the forward arrangement, the respective hubs of the left and right inboard propulsion assemblies are forward of the respective hubs of the left and right outboard propulsion assemblies, and wherein in the hover arrangement, the respective hubs of the left and right inboard propulsion assemblies are forward of the respective hubs of the left and right outboard propulsion assemblies, and wherein in the forward arrangement the respective hubs of the left and right inboard propulsion assemblies are higher than the respective hubs of the left and right outboard propulsion assemblies;
• wherein a spacing between the hubs of the left inboard and left outboard propulsion assemblies changes between the forward arrangement and the hover arrangement.