A method for controlling a hybrid helicopter having at least one lifting rotor, at least one forward-movement propeller and an empennage provided with at least one moveable empennage surface. The method includes the following steps: using a main sensor to determine a current value of a rotor parameter conditioning a current power drawn by the lifting rotor, using an estimator to determine a current setpoint of the rotor parameter, adjusting a position of the moveable empennage surface using a deflection controller as a function of the current value and of current setpoint.

An aircraft includes an airframe with first and second wings having a fuselage extending therebetween. A propulsion assembly is coupled to the fuselage and includes a counter-rotating coaxial rotor system that is tiltable relative to the fuselage to generate a thrust vector. First and second yaw vanes extend aftwardly from the fuselage. A flight control system is configured to direct the thrust vector of the coaxial rotor system and control movements of the yaw vanes. In a VTOL orientation of the aircraft, differential operation of the yaw vanes and/or differential operations of first and second rotor assemblies of the coaxial rotor system provide yaw authority for the aircraft. In a biplane orientation of the aircraft, collective operation of the yaw vanes provides yaw authority for the aircraft.

An aircraft includes an airframe with first and second wings having a fuselage extending therebetween. A propulsion assembly is coupled to the fuselage and includes a counter-rotating coaxial rotor system that is tiltable relative to the fuselage to generate a thrust vector. First and second yaw vanes extend aftwardly from the fuselage. A flight control system is configured to direct the thrust vector of the coaxial rotor system and control movements of the yaw vanes. In a VTOL orientation of the aircraft, differential operation of the yaw vanes and/or differential operations of first and second rotor assemblies of the coaxial rotor system provide yaw authority for the aircraft. In a biplane orientation of the aircraft, collective operation of the yaw vanes provides yaw authority for the aircraft.

A rotorcraft has a horizontal stabilizer movable about an axis of rotation and a horizontal stabilizer control system configured to control the horizontal stabilizer to at least one of move the rotorcraft into a minimum drag position, maintain the aircraft in a minimum drag position, efficiently achieve a maneuver, enter efficient autorotation, and maintain efficient autorotation.

An aircraft includes a structure exhibiting a median plane XZ and including a fuselage, a fixed vertical stabilizer at the rear of the fuselage, an adjustable horizontal stabilizer rotatably mounted about a horizontal axis on a first section of the structure, and extending on either side of the median plane XZ, and at the rear, two elevators mounted rotatably about a horizontal axis on a second section of the structure on either side of the median plane XZ independently of the adjustable horizontal stabilizer. In an aircraft of this kind, the elevators no longer have any impact on the adjustable horizontal stabilizer, which allows, among other things, the dimensions of the adjustable horizontal stabilizer, and also of the actuator operating them, to be reduced.

An aircraft includes a structure exhibiting a median plane XZ and including a fuselage, a fixed vertical stabilizer at the rear of the fuselage, an adjustable horizontal stabilizer rotatably mounted about a horizontal axis on a first section of the structure, and extending on either side of the median plane XZ, and at the rear, two elevators mounted rotatably about a horizontal axis on a second section of the structure on either side of the median plane XZ independently of the adjustable horizontal stabilizer. In an aircraft of this kind, the elevators no longer have any impact on the adjustable horizontal stabilizer, which allows, among other things, the dimensions of the adjustable horizontal stabilizer, and also of the actuator operating them, to be reduced.

A passive gust load alleviation device for an aerodynamic panel includes a free-floating aerodynamic control surface connected to the panel via a revolute joint. A counterweight is connected to the control surface. Relative to a direction of ambient airflow, the counterweight has a center of gravity forward of the axis of rotation. The counterweight is configured to passively deflect the control surface about the axis to alleviate a gust load. A vehicle includes an aerodynamic panel connected to a body and extending into ambient airflow, and the control surface and counterweight. A method for alleviating the gust load on an aircraft panel includes connecting the control panel, via the revolute joint, along a trailing edge of the panel, and during a flight of an aircraft having the panel, passively deflecting the control panel about the axis in response to an incident wind gust.

A passive gust load alleviation device for an aerodynamic panel includes a free-floating aerodynamic control surface connected to the panel via a revolute joint. A counterweight is connected to the control surface. Relative to a direction of ambient airflow, the counterweight has a center of gravity forward of the axis of rotation. The counterweight is configured to passively deflect the control surface about the axis to alleviate a gust load. A vehicle includes an aerodynamic panel connected to a body and extending into ambient airflow, and the control surface and counterweight. A method for alleviating the gust load on an aircraft panel includes connecting the control panel, via the revolute joint, along a trailing edge of the panel, and during a flight of an aircraft having the panel, passively deflecting the control panel about the axis in response to an incident wind gust.

In one embodiment, an apparatus includes a first deflector configured to couple to a shaft of a wing of an aircraft and form part of a top surface of the wing when in a first closed position, and a second deflector configured to couple to the shaft and form part of a bottom surface of the wing when in a second closed position. The first deflector and the second deflector may be configured to be positioned proximate to the tip of the wing. The first deflector and the second deflector may be configured to simultaneously pivot from the closed positions to respective first and second open positions upon actuation of the shaft.

In one embodiment, an apparatus includes a first deflector configured to couple to a shaft of an aircraft. The first deflector may form part of a top surface of the aircraft when in a first closed position. The apparatus may further include a second deflector configured to couple to the shaft and form part of a bottom surface of the aircraft when in a second closed position. The first deflector and the second deflector may be configured to be positioned at a junction of a body of the aircraft and a wing of the aircraft. The first deflector and the second deflector may be configured to simultaneously pivot from the closed positions to respective first and second open positions upon actuation of the shaft.