US 12,304,626 B2
Rotorcraft with a ducted tail rotor supported by a stator
Rupert Pfaller, Riemerling (DE); and Tobias Ries, Nordendorf (DE)
Assigned to Airbus Helicopters Deutschland GmbH, Donauworth (DE)
Filed by AIRBUS HELICOPTERS DEUTSCHLAND GMBH, Donauworth (DE)
Filed on Jul. 17, 2023, as Appl. No. 18/222,583.
Claims priority of application No. 22204458 (EP), filed on Oct. 28, 2022.
Prior Publication US 2024/0140601 A1, May 2, 2024
Int. Cl. B64C 27/82 (2006.01); B64C 11/00 (2006.01); B64C 27/54 (2006.01)
CPC B64C 27/54 (2013.01) [B64C 11/001 (2013.01); B64C 27/82 (2013.01); B64C 2027/8254 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A rotorcraft with at least one main rotor and a fuselage, comprising:
a tail boom connected to the fuselage, the tail boom extending from the fuselage toward a duct-type portion;
a shroud provided at the duct-type portion and forming a transverse duct;
at least one ducted tail rotor rotatably arranged in the transverse duct, wherein the at least one ducted tail rotor comprises a plurality of rotor blades mounted to a rotatable rotor hub; and
a stator with a gearbox fairing mounted to the shroud for supporting the rotatable rotor hub in the transverse duct, wherein the stator comprises at least one rotatable stator blade connecting the gearbox fairing to the shroud, and a torsion spring connected to the at least one rotatable stator blade;
wherein the at least one rotatable stator blade has a wing body having a wing aerodynamic profile, the at least one rotatable stator blade having a leading edge and a trailing edge, each wing aerodynamic profile has an aerodynamic center acting as a pressure point, wherein the at least one rotatable stator blade is rotatably mounted to a stationary strut which forms a rotation axis for the wing body, the at least one rotatable stator blade rotatable between a first hover flight position and a second forward flight position, the first hover flight position being perpendicular to the rotation disc of the ducted tail rotor and associated with a hover flight condition of the rotorcraft, the torsion spring to bias the at least one rotatable stator blade towards the first hover flight position; and
wherein the aerodynamic center is spaced apart from the rotation axis, and the rotation axis is arranged closer to the leading edge than the aerodynamic center, in front of the aerodynamic center, thus producing an airflow induced pressure on the wing aerodynamic profile generating a torque moment which causes rotation of the wing body around the rotation axis into a position of reduced aerodynamic drag.