Abstract: A proprotor assembly for a tiltrotor aircraft having a forward flight mode. The proprotor assembly includes a spinner subjected to freestream airflow during forward flight. The spinner is elongated to form a tapered leading portion and a substantially cylindrical aft portion. The spinner forms a plurality of rotor blade cutouts exposing an inner chamber. The proprotor assembly includes a plurality of proprotor blade assemblies protruding radially from the spinner through the rotor blade cutouts. The rotor blade cutouts are formed at the substantially cylindrical aft portion of the spinner to reduce the freestream airflow into the inner chamber via the rotor blade cutouts during forward flight, thereby reducing drag experienced by the tiltrotor aircraft.

Abstract: A tiltrotor aircraft is operable in a helicopter flight mode and an airplane flight mode. The tiltrotor aircraft has an airframe including a fuselage and a wing. First and second pylon assemblies are respectively coupled to the airframe proximate outboard ends of the wing. Each pylon assembly includes a mast and a proprotor assembly operable to rotate with the mast to generate thrust. The pylon assemblies are rotatable relative to the wing to selectively operate the tiltrotor aircraft between the helicopter flight mode and the airplane flight mode. The thrust of each proprotor assembly has a thrust vector with an inboard angle between about 5 degrees and about 12 degrees relative to an axis parallel to the yaw axis during hover operations, thereby reducing download on the airframe and improving hover efficiency.

Abstract: A proprotor assembly for a tiltrotor aircraft having a forward flight mode. The proprotor assembly includes a spinner subjected to freestream airflow during forward flight. The spinner is elongated to form a tapered leading portion and a substantially cylindrical aft portion. The spinner forms a plurality of rotor blade cutouts exposing an inner chamber. The proprotor assembly includes a plurality of proprotor blade assemblies protruding radially from the spinner through the rotor blade cutouts. The rotor blade cutouts are formed at the substantially cylindrical aft portion of the spinner to reduce the freestream airflow into the inner chamber via the rotor blade cutouts during forward flight, thereby reducing drag experienced by the tiltrotor aircraft.