US 11,713,112 B2
Method and a system for reducing the in-flight noise from a hybrid helicopter by managing the angle of incidence of its main rotor and the thrust from each propeller
Frederic Guntzer, Gignac la Nerthe (FR); and Paul Eglin, Roquefort la Bedoule (FR)
Assigned to AIRBUS HELICOPTERS, Marignane (FR)
Filed by AIRBUS HELICOPTERS, Marignane (FR)
Filed on Mar. 10, 2021, as Appl. No. 17/197,749.
Claims priority of application No. 2002631 (FR), filed on Mar. 18, 2020.
Prior Publication US 2021/0291969 A1, Sep. 23, 2021
Int. Cl. B64C 27/26 (2006.01); B64C 27/82 (2006.01); B64C 27/57 (2006.01); B64C 11/30 (2006.01)
CPC B64C 27/26 (2013.01) [B64C 11/305 (2013.01); B64C 27/82 (2013.01); B64C 27/57 (2013.01); B64C 2027/8236 (2013.01); B64C 2027/8272 (2013.01); B64C 2027/8281 (2013.01); B64C 2220/00 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method of reducing in-flight noise for a hybrid helicopter,
wherein the method comprises the following steps:
determining flight conditions of the hybrid helicopter;
wherein the hybrid helicopter includes:
at least one main rotor provided with a plurality of blades and providing the hybrid helicopter with at least part of its lift and/or forward propulsion;
at least one propeller provided with a plurality of blades and providing the hybrid helicopter with at least part of its forward propulsion;
an automatic piloting device; and
at least one calculator;
wherein flight conditions of the hybrid helicopter are determined using at least one sensor of the hybrid helicopter, the flight conditions including a speed relative to air of the hybrid helicopter and an aerodynamic slope of a path followed by the hybrid helicopter;
determining a value of a thrust to be exerted by the propeller(s) using a first database and as a function of the flight conditions;
determining a value of an angle of incidence to be had by the main rotor(s) using a second database and as a function of the value of the thrust to be exerted by the propeller(s) so as to limit noise generation due to a vortex wake caused by each rotating blade of the main rotor(s); and
implementing a stabilized flight phase of the hybrid helicopter by controlling the propeller(s) to exert a thrust commensurate with the value of the thrust to be exerted by the propeller(s) and by controlling the main rotor(s) to have an angle of incidence commensurate with the value of the angle of incidence to be had by the main rotor(s).