Abstract: An aircraft includes at least two propulsion units being pivotable and arranged adjacent to each other along an arrangement direction. The propulsion units include a propulsion rotor and a duct for guiding air to the rotor. The duct has a non-circular inlet portion, a circular downstream portion located downstream of the inlet portion along the airflow direction, and an air guiding portion guiding air from the non-circular inlet portion to the circular downstream portion and establishing the transition therebetween. The air guiding portion has upper and lower portions. The aircraft further includes at least one septum interposed between rotation axes of two adjacent propulsion rotors. The septum extends on the upstream side along the airflow direction with respect to the circular downstream portion and between the upper and lower air guiding portions and has a guiding surface having at least one tangential plane parallel to the rotation axis.

Abstract: An aircraft includes at least two propulsion units being pivotable and arranged adjacent to each other along an arrangement direction. The propulsion units include a propulsion rotor and a duct for guiding air to the rotor. The duct has a non-circular inlet portion, a circular downstream portion located downstream of the inlet portion along the airflow direction, and an air guiding portion guiding air from the non-circular inlet portion to the circular downstream portion and establishing the transition therebetween. The air guiding portion has upper and lower portions. The aircraft further includes at least one septum interposed between rotation axes of two adjacent propulsion rotors. The septum extends on the upstream side along the airflow direction with respect to the circular downstream portion and between the upper and lower air guiding portions and has a guiding surface having at least one tangential plane parallel to the rotation axis.