Abstract: A rotorcraft having an aerodynamic device arranged below a rotor, which rotor participates at least in providing lift for the rotorcraft, the rotor being mounted to rotate about an axis of rotation, the aerodynamic device having a fairing provided with at least one air inlet for enabling a stream of cool air to flow from a region that is situated outside the rotorcraft to another region that is situated inside, the air inlet being delimited by an outer peripheral portion of the fairing. In accordance with the invention, the aerodynamic device has a perforated plate provided with at least one perforation, the perforation being suitable for allowing the stream of cool air to pass through it, the perforated plate having at least one main portion shaped to match an outer shape of the outer peripheral portion of said fairing.

Abstract: A method for controlling a thermal and electrical power plant for setting in motion at least one rotary member of a rotorcraft, the power plant comprising at least one heat engine and an electrical system provided with at least one electric machine. The method comprises: selecting, with a selector, an operating mode chosen from several operating modes; determining a density altitude and comparing, with a controller, the current density altitude and a threshold density altitude; and controlling, with the controller, the at least one electric machine depending on at least the chosen operating mode as well as the comparison and a necessary power to be supplied to the power transmission system.

Abstract: A rotorcraft and to a regulation method for regulating a power plant of a rotorcraft, the power plant having two engine units and a main gearbox, the two engine units being suitable for mechanically driving the main gearbox in order to drive an outlet main shaft of the main gearbox in rotation, the outlet main shaft being constrained to rotate with a main rotor of the rotorcraft, the two engine units including a first engine unit including at least one main engine. In accordance with the invention, such a regulation method includes at least one regulation step consisting in regulating a speed of rotation of the at least one main engine by progressively reducing a current setpoint by an increment i in percentage of the current setpoint per second.

Abstract: A rotorcraft having an antivibration system, the antivibration system being arranged at the interface between a fuselage of the rotorcraft and a casing of a main power transmission gearbox, or “MGB”, in order to transmit rotary motion generated by an engine of the rotorcraft to a main rotor providing the rotorcraft at least with lift, and possibly also propulsion, the antivibration system including calculation means for analyzing as a function of time the dynamic excitation and the resulting vibration transmitted to the fuselage of the rotorcraft.

Abstract: A crank device provided with an upstream lever and with a downstream lever. The crank device includes a phase shifter system connected to the upstream lever and to the downstream lever so that movement in rotation of the upstream lever about an axis of rotation induces movement in rotation of the downstream lever about the axis of rotation, the phase shifter system comprising a linear actuator mechanism carried by the upstream lever, the linear actuator mechanism having an outlet rod, the outlet rod having only one degree of freedom of movement in translation relative to the upstream lever, the outlet rod being connected via an outlet helical connection to the downstream lever so that movement in translation of the outlet rod generates movement in rotation of the downstream lever about the axis of rotation.

Abstract: A rotorcraft and to a regulation method for regulating a power plant of a rotorcraft, the power plant having two engine units and a main gearbox, the two engine units being suitable for mechanically driving the main gearbox in order to drive an outlet main shaft of the main gearbox in rotation, the outlet main shaft being constrained to rotate with a main rotor of the rotorcraft, the two engine units including a first engine unit including at least one main engine. In accordance with the invention, such a regulation method includes at least one regulation step consisting in regulating a speed of rotation of the at least one main engine by progressively reducing a current setpoint by an increment i in percentage of the current setpoint per second.

Abstract: A rotorcraft having an aerodynamic device arranged below a rotor, which rotor participates at least in providing lift for the rotorcraft, the rotor being mounted to rotate about an axis of rotation, the aerodynamic device having a fairing provided with at least one air inlet for enabling a stream of cool air to flow from a region that is situated outside the rotorcraft to another region that is situated inside, the air inlet being delimited by an outer peripheral portion of the fairing. In accordance with the invention, the aerodynamic device has a perforated plate provided with at least one perforation, the perforation being suitable for allowing the stream of cool air to pass through it, the perforated plate having at least one main portion shaped to match an outer shape of the outer peripheral portion of said fairing.

Abstract: A crank device provided with an upstream lever and with a downstream lever. The crank device includes a phase shifter system connected to the upstream lever and to the downstream lever so that movement in rotation of the upstream lever about an axis of rotation induces movement in rotation of the downstream lever about the axis of rotation, the phase shifter system comprising a linear actuator mechanism carried by the upstream lever, the linear actuator mechanism having an outlet rod, the outlet rod having only one degree of freedom of movement in translation relative to the upstream lever, the outlet rod being connected via an outlet helical connection to the downstream lever so that movement in translation of the outlet rod generates movement in rotation of the downstream lever about the axis of rotation.

Abstract: A plate heat exchanger comprising a plurality of plates having a plane peripheral zone, an inner zone having sinusoidal undulations and two chimneys positioned at two opposite corners of the plates. Modules are formed by assembling two plates that make contact via the undulation troughs and the peripheral zones. The modules are stacked so as to make contact via the inlet and outlet chimneys. Each module may thus deform independently, in particular at the undulation troughs and ridges without transmitting stress to the other modules of the heat exchanger. In addition, the heat exchanger may comprise a tie rod in each inlet and outlet pipe so as to withstand the static pressure of the fluids flowing in the pipes.

Abstract: A control device for controlling an aircraft, the control device including at least one motor-driven trim actuator with active type anchoring, the trim actuator including at least one electric motor, at least one electronic power circuit for electrically powering the electric motor(s), and speed reduction means for driving rotation of an outlet shaft of the trim actuator. The control device implements three distinct servo-control loops that are nested in one another, these three servo-control loops being formed by an electric current servo-control loop, a speed servo-control loop, and a force servo-control loop.

Abstract: A rotor comprising a hub and a plurality of lift assemblies. Each lift assembly is connected to two adjacent lift assemblies respectively by a first damper and a second damper. The first damper is hinged to a lift assembly about a first axis, and the second damper is hinged to said lift assembly about a second axis. A first plane contains a lead-lag axis of the lift assembly and orthogonally to the pitch axis of the lift assembly. The first axis is situated in a volume lying between the first plane and an axis of rotation of the rotor, the second axis being positioned outside said volume.

Abstract: A rotorcraft having an antivibration system, the antivibration system being arranged at the interface between a fuselage of the rotorcraft and a casing of a main power transmission gearbox, or “MGB”, in order to transmit rotary motion generated by an engine of the rotorcraft to a main rotor providing the rotorcraft at least with lift, and possibly also propulsion, the antivibration system including calculation means for analyzing as a function of time the dynamic excitation and the resulting vibration transmitted to the fuselage of the rotorcraft.

Abstract: A control device for controlling an aircraft, the control device including at least one motor-driven trim actuator with active type anchoring, the trim actuator including at least one electric motor, at least one electronic power circuit for electrically powering the electric motor(s), and speed reduction means for driving rotation of an outlet shaft of the trim actuator. The control device implements three distinct servo-control loops that are nested in one another, these three servo-control loops being formed by an electric current servo-control loop, a speed servo-control loop, and a force servo-control loop.

Abstract: A rotor comprising a hub and a plurality of lift assemblies. Each lift assembly is connected to two adjacent lift assemblies respectively by a first damper and a second damper. The first damper is hinged to a lift assembly about a first axis, and the second damper is hinged to said lift assembly about a second axis. A first plane contains a lead-lag axis of the lift assembly and orthogonally to the pitch axis of the lift assembly. The first axis is situated in a volume lying between the first plane and an axis of rotation of the rotor, the second axis being positioned outside said volume.

Abstract: A plate heat exchanger comprising a plurality of plates having a plane peripheral zone, an inner zone having sinusoidal undulations and two chimneys positioned at two opposite corners of the plates. Modules are formed by assembling two plates that make contact via the undulation troughs and the peripheral zones. The modules are stacked so as to make contact via the inlet and outlet chimneys. Each module may thus deform independently, in particular at the undulation troughs and ridges without transmitting stress to the other modules of the heat exchanger. In addition, the heat exchanger may comprise a tie rod in each inlet and outlet pipe so as to withstand the static pressure of the fluids flowing in the pipes.

Abstract: A gas exhaust nozzle for a gas turbine, the exhaust nozzle having an annular inlet section centered on the axis of the gas turbine, a diffuser, a plenum chamber, and an expansion nozzle. The diffuser extends around the axis with a shape that diverges from the inlet section to the plenum chamber, and comprises an inner first surface and an outer first surface that are concave on the same side. The plenum chamber extends around the axis and is defined firstly by the diffuser and secondly by an outer second surface extending the inner first surface and joining the outer first surface. The plenum chamber includes a radial opening leading into the expansion nozzle, the exhaust gas leaving the expansion nozzle perpendicularly to the axis.

Abstract: A power plant (10) having a main gearbox (20), a turbine engine (40), and a heat exchanger (60), the main gearbox (20) including a substantially vertical rotor mast (21). The main gearbox (20) comprises at least a rotary speed reduction stage arranged in a flat casing (22), and a pylon (23). The turbine engine (40) has an engine casing (42) with an outlet shaft projecting from said engine casing (42) and penetrating into said flat casing (22), said outlet shaft (41) being substantially parallel to the rotor mast (21), said engine casing (42) being offset longitudinally from the pylon (23) and not being in contact with the pylon (23). The heat exchanger (60) extends longitudinally behind said turbine engine (40), while, on the contrary, said rotor mast (21) is situated longitudinally in front of said turbine engine (40).

Abstract: A plate heat exchanger having a plurality of plates with sinusoidal undulations and two chimneys positioned at two opposite corners of the plates. Modules are formed by assembling together pairs of plates, the modules being stacked so as to make contact via the inlet and outlet chimneys in order to form the heat exchanger. The sinusoidal undulations form a first angle ? with the flow direction of the fluids in the heat exchanger, the first angle ? increasing in the flow direction of a first fluid through the modules. Furthermore, each plate has two distribution zones for distributing the first fluid in the modules in the proximity of each inlet or outlet chimney in order to make the filling and the discharge of the modules by the first fluid more uniform.

Abstract: A power plant (10) having a main gearbox (20), a turbine engine (40), and a heat exchanger (60), the main gearbox (20) including a substantially vertical rotor mast (21). The main gearbox (20) comprises at least a rotary speed reduction stage arranged in a flat casing (22), and a pylon (23). The turbine engine (40) has an engine casing (42) with an outlet shaft projecting from said engine casing (42) and penetrating into said flat casing (22), said outlet shaft (41) being substantially parallel to the rotor mast (21), said engine casing (42) being offset longitudinally from the pylon (23) and not being in contact with the pylon (23). The heat exchanger (60) extends longitudinally behind said turbine engine (40), while, on the contrary, said rotor mast (21) is situated longitudinally in front of said turbine engine (40).

Abstract: A volute (10) with two chambers for a gas turbine (50), including a circumferential conduit (11) in the form of a spiral, a first opening (12) oriented tangentially to the said circumferential conduit (11), toward the outside of the said circumferential conduit (11), and a second circumferential opening (13) located at the center of the said circumferential conduit (11). A wall (15) separates the said circumferential conduit (11) into two symmetrical chambers (18) (19), with a first fluid and a second fluid being able to circulate independently and in an isolated manner between the said first opening (12) and the said second opening (13). The said first opening (12) allows a linear flow of the two fluids between the said circumferential conduit (11) and a chamber exterior to the said circumferential conduit (11), while the said second opening (13) allows a radial flow of the said two fluids between the said circumferential conduit (11) and a chamber interior to the said circumferential conduit (11).