an aircraft with high transport efficiency, wherein the aircraft include a blended wing body with a downward depressed upper aft surface, configured to operate at a high cruising level within a high cruise altitude range, wherein the blended wing body include a main body configured to accommodate a payload, and at least a wing, wherein the blended wing body include no striking demarcation between the main body and the at least a wing and at least a propulsor attached to the blended wing body and configured to propel the aircraft.