A simple, safe, and inexpensive flight control system in an aircraft. An anti-torque system for a rotary-wing aircraft has an airfoil with a first surface extending from a first trailing edge and a leading edge, and a second surface extending from a second trailing edge to join the first surface at the leading edge. The airfoil has a first moveable deflector panel pivotally coupled to the first trailing edge, and a second moveable deflector panel pivotally coupled to the second trailing edge. Means are provided to pivot the deflector panels in unison about their respective pivot axes to alter the direction of travel of the airflow downstream of the pivot axes over the surfaces of the deflector panels, thereby producing a lift in a direction perpendicular to the airflow to counteract the torque applied on the aircraft. The flight control system may be arranged within a fixed-wing aircraft.

A simple, safe, and inexpensive flight control system in an aircraft. An anti-torque system for a rotary-wing aircraft has an airfoil with a first surface extending from a first trailing edge and a leading edge, and a second surface extending from a second trailing edge to join the first surface at the leading edge. The airfoil has a first moveable deflector panel pivotally coupled to the first trailing edge, and a second moveable deflector panel pivotally coupled to the second trailing edge. Means are provided to pivot the deflector panels in unison about their respective pivot axes to alter the direction of travel of the airflow downstream of the pivot axes over the surfaces of the deflector panels, thereby producing a lift in a direction perpendicular to the airflow to counteract the torque applied on the aircraft. The flight control system may be arranged within a fixed-wing aircraft.

A rotary wing aircraft that extends along an associated roll axis between a nose region and an aft region and that comprises a fuselage with a front section and a rear section, the rotary wing aircraft comprising: a main rotor that is rotatably mounted at the front section, a shrouded duct that is arranged in the aft region, and a propeller that is rotatably mounted to the shrouded duct, wherein the rear section extends between the front section and the shrouded duct and comprises an asymmetrical cross-sectional profile in direction of the associated roll axis.

A rotary wing aircraft that extends along an associated roll axis between a nose region and an aft region and that comprises a fuselage with a front section and a rear section, the rotary wing aircraft comprising: a main rotor that is rotatably mounted at the front section, a shrouded duct that is arranged in the aft region, and a propeller that is rotatably mounted to the shrouded duct, wherein the rear section extends between the front section and the shrouded duct and comprises an asymmetrical cross-sectional profile in direction of the associated roll axis.

A gear system for a rotary wing aircraft includes a first gear including an inner gear portion having a first pitch and an outer gear portion having a second pitch that is distinct from the first pitch. A second gear includes a third pitch driven at a driving rotational speed. An actuator member is coupled to the second gear while driven at the driving rotational speed. The actuator member shifts the second gear along the first gear to engage with one of the inner gear portion and the outer gear portion to drive the first gear at a first rotational speed and engage with other one of the inner gear portion and the outer gear portion to drive the first gear at a second rotational speed. A controller is operable to control the actuator member to shift the second gear between the inner gear portion and the outer gear portion.

A gear system for a rotary wing aircraft includes a first gear including an inner gear portion having a first pitch and an outer gear portion having a second pitch that is distinct from the first pitch. A second gear includes a third pitch driven at a driving rotational speed. An actuator member is coupled to the second gear while driven at the driving rotational speed. The actuator member shifts the second gear along the first gear to engage with one of the inner gear portion and the outer gear portion to drive the first gear at a first rotational speed and engage with other one of the inner gear portion and the outer gear portion to drive the first gear at a second rotational speed. A controller is operable to control the actuator member to shift the second gear between the inner gear portion and the outer gear portion.

In an asymmetric operating regime, a first engine is operating in an active mode to provide motive power to an aircraft while a second engine is operating in a standby mode and de-clutched from a gearbox of the aircraft. In response to an emergency exit request, the second engine's speed is increased, at a maximum permissible rate, to a re-clutching speed while increasing the first engine's power output at a maximum permissible rate. When the re-clutching speed is reached, the second engine's power output is increased at a maximum permissible rate. In response to a normal exit request, the second engine's speed is increased to the re-clutching speed at a rate lower than the maximum permissible rate. When the re-clutching speed is reached, the second engine's power output is increased at a rate lower than the maximum permissible rate.

A method and apparatus for estimating an airspeed of a rotorcraft by analyzing its rotor. The rotorcraft includes a fuselage and a main rotor that is equipped with a plurality of blades and that rotates about an axis of a hub of the rotor, and in which the free end or “tip” of each blade describes a path in the vicinity of a tip-path plane. The method makes it possible to determine said airspeed of the rotorcraft in a frame of reference united with the tip-path plane by solving a model of the rotor that puts a pitch angle of at least one blade relative to the tip-path plane into relation with the airspeed of the rotorcraft and with an auxiliary speed. The auxiliary speed may be an induced velocity of the air flowing through the rotor or else an axial airspeed at the upstream infinity of the rotorcraft.

A method and apparatus for estimating an airspeed of a rotorcraft by analyzing its rotor. The rotorcraft includes a fuselage and a main rotor that is equipped with a plurality of blades and that rotates about an axis of a hub of the rotor, and in which the free end or “tip” of each blade describes a path in the vicinity of a tip-path plane. The method makes it possible to determine said airspeed of the rotorcraft in a frame of reference united with the tip-path plane by solving a model of the rotor that puts a pitch angle of at least one blade relative to the tip-path plane into relation with the airspeed of the rotorcraft and with an auxiliary speed. The auxiliary speed may be an induced velocity of the air flowing through the rotor or else an axial airspeed at the upstream infinity of the rotorcraft.

A power management system for a multi engine rotorcraft having a main rotor system with a main rotor speed. The power management system includes a first engine that provides a first power input to the main rotor system. A second engine selectively provides a second power input to the main rotor system. The second engine has at least a zero power input state and a positive power input state. A power anticipation system is configured to provide the first engine with a power adjustment signal in anticipation of a power input state change of the second engine during flight. The power adjustment signal causes the first engine to adjust the first power input to maintain the main rotor speed within a predetermined rotor speed threshold range during the power input state change of the second engine.