Abstract: Embodiments are directed to operating a multi-engine aircraft during a cruise flight condition. A first engine is put off-line during flight while allowing a second engine to continue operating. The second engine provides sufficient power to maintain the multi-engine aircraft in the cruise flight condition. An outside air temperature, a first engine temperature, and/or an engine oil temperature is monitored and, when the temperature is below a predetermined threshold, the engine oil for the off-line first engine is warmed. The off-line engine oil may be warmed by continuously or periodically cranking the first engine without restarting the first engine. Alternatively, the engine oil may be warmed using a heat exchanger, such as an air-to-oil or oil-to-oil heat exchanger, or by using electronic heaters on an oil tank.

Abstract: An electrically distributed yaw control system for a helicopter having a tailboom and a power system includes one or more tail rotors including a motor rotatably coupled to the tailboom and a power distribution unit. The power distribution unit includes a power management monitoring module configured to monitor one or more flight parameters of the helicopter and a power management command module configured to allocate power between the power system and the one or more tail rotor motors based on the one or more flight parameters of the helicopter.

Abstract: A yaw control system coupled to a tailboom of a helicopter includes tail rotors. The tail rotors include a clockwise tail rotor and a counterclockwise tail rotor. The clockwise tail rotor is configured to rotate in a first rotational direction. The counterclockwise tail rotor is configured to rotate in a second rotational direction, the second rotational direction opposite of the first rotational direction.

Abstract: An architecture for an electric distributed propulsion system includes one or more generators connected to a gearbox, a first and a second plurality of motors connected to the one or more generators, each motor of the plurality of motors connected to a blade to provide thrust, a first and a second power bus electrically connected between the one or more generators and the first and the second plurality of motors, each power bus independent of the other power bus, a first and a second controller independently connected to each of the first and second plurality of motors, each of the first and second controllers serving as a primary and a backup controller, and dual channels in communication between pilot input sensors and the first and the second controllers, and the dual channels including an additional channel to provide redundant communication to the first and second controllers.

Abstract: A yaw control system for a helicopter having a tailboom and a forward flight mode includes a surface coupled to the tailboom, one or more tail rotors coupled to the surface, a flight control computer implementing a yaw controller having a rudder control module and a tail rotor rotational speed reduction module and a rudder rotatably coupled to the surface. The tail rotor rotational speed reduction module is configured to selectively switch the one or more tail rotors into a rotational speed reduction mode in the helicopter forward flight mode. The rudder control module is configured to rotate the rudder in the rotational speed reduction mode of the one or more tail rotors to control the yaw of the helicopter.

Abstract: A yaw control system for a helicopter having an airframe that includes a tailboom includes one or more tail rotors rotatably coupled to the tailboom and a flight control computer implementing an airframe protection module. The airframe protection module includes an airframe protection monitoring module configured to monitor one or more flight parameters of the helicopter and an airframe protection command module configured to modify one or more operating parameters of the one or more tail rotors based on the one or more flight parameters of the helicopter, thereby protecting the airframe of the helicopter.

Abstract: A yaw control system for a helicopter having a tailboom includes one or more tail rotors rotatably coupled to the tailboom and a quiet mode controller. The quiet mode controller includes a noise monitoring module configured to monitor one or more flight parameters of the helicopter and a quiet mode command module configured to selectively switch the one or more tail rotors to a quiet mode based on the one or more flight parameters. The quiet mode command module is also configured to modify one or more operating parameters of the one or more tail rotors in the quiet mode to reduce noise emitted by the helicopter.

Abstract: An electrically distributed yaw control system for a helicopter having a tailboom includes a plurality of tail rotors rotatably coupled to the tailboom and a flight control computer implementing a tail rotor balancing module. The tail rotor balancing module includes a tail rotor balancing monitoring module configured to monitor one or more parameters of the helicopter and identify a first set of one or more tail rotors in the plurality of tail rotors based on the one or more parameters. The tail rotor balancing module also includes a tail rotor balancing command module configured to modify one or more operating parameters of the first set of tail rotors.

Abstract: A rotorcraft includes a substantially rigid structural body. The structural body has an internal cavity and an aperture extending entirely through the structural body. The rotorcraft further includes at least one of a tail boom and a fuselage. The rotorcraft further includes a propulsion device disposed at least partially within the internal cavity and at least partially within the aperture. The propulsion device is carried by the structural body so that forces are transferred from the propulsion device to at least one of the tail boom and the fuselage via the structural body.

Abstract: A yaw control system coupled to a tailboom of a helicopter includes tail rotors. The tail rotors include a clockwise tail rotor and a counterclockwise tail rotor. The clockwise tail rotor is configured to rotate in a first rotational direction. The counterclockwise tail rotor is configured to rotate in a second rotational direction, the second rotational direction opposite of the first rotational direction.

Abstract: A yaw control system for a helicopter having a tailboom includes one or more tail rotors rotatably coupled to the tailboom and a quiet mode controller. The quiet mode controller includes a noise monitoring module configured to monitor one or more flight parameters of the helicopter and a quiet mode command module configured to selectively switch the one or more tail rotors to a quiet mode based on the one or more flight parameters. The quiet mode command module is also configured to modify one or more operating parameters of the one or more tail rotors in the quiet mode to reduce noise emitted by the helicopter.

Abstract: A yaw control system for a helicopter having a tailboom and a forward flight mode includes a surface coupled to the tailboom, one or more tail rotors coupled to the surface, a flight control computer implementing a yaw controller having a rudder control module and a tail rotor rotational speed reduction module and a rudder rotatably coupled to the surface. The tail rotor rotational speed reduction module is configured to selectively switch the one or more tail rotors into a rotational speed reduction mode in the helicopter forward flight mode. The rudder control module is configured to rotate the rudder in the rotational speed reduction mode of the one or more tail rotors to control the yaw of the helicopter.

Abstract: An electrically distributed yaw control system for a helicopter having a tailboom includes a plurality of tail rotors rotatably coupled to the tailboom and a flight control computer implementing a tail rotor balancing module. The tail rotor balancing module includes a tail rotor balancing monitoring module configured to monitor one or more parameters of the helicopter and identify a first set of one or more tail rotors in the plurality of tail rotors based on the one or more parameters. The tail rotor balancing module also includes a tail rotor balancing command module configured to modify one or more operating parameters of the first set of tail rotors.

Abstract: A yaw control system for a helicopter having an airframe that includes a tailboom includes one or more tail rotors rotatably coupled to the tailboom and a flight control computer implementing an airframe protection module. The airframe protection module includes an airframe protection monitoring module configured to monitor one or more flight parameters of the helicopter and an airframe protection command module configured to modify one or more operating parameters of the one or more tail rotors based on the one or more flight parameters of the helicopter, thereby protecting the airframe of the helicopter.

Abstract: An electrically distributed yaw control system for a helicopter having a tailboom and a power system includes one or more tail rotors including a motor rotatably coupled to the tailboom and a power distribution unit. The power distribution unit includes a power management monitoring module configured to monitor one or more flight parameters of the helicopter and a power management command module configured to allocate power between the power system and the one or more tail rotor motors based on the one or more flight parameters of the helicopter.

Abstract: An architecture for an electric distributed propulsion system includes one or more generators connected to a gearbox, a first and a second plurality of motors connected to the one or more generators, each motor of the plurality of motors connected to a blade to provide thrust, a first and a second power bus electrically connected between the one or more generators and the first and the second plurality of motors, each power bus independent of the other power bus, a first and a second controller independently connected to each of the first and second plurality of motors, each of the first and second controllers serving as a primary and a backup controller to provide redundant control to both the first and the second plurality of motors, and dual channels in communication between pilot input sensors and the first and the second controllers, each channel of the dual channels independent of the other channels, and the dual channels including an additional channel to provide redundant communication to the first an

Abstract: An exemplary continuous variable pitch rotor system includes a blade extending radially from a hub along a longitudinal axis, the blade rotationally coupled to the hub to permit limited rotation of the blade about the longitudinal axis in response to a change in a rotational speed of the hub. In some embodiments, the blade is held in a radially fixed position relative to the hub. In some embodiments, the blade is permitted to translate radially.

Abstract: An exemplary distributed propulsion system with thermal management includes two or more rotors individually controlled by associated motors and an input control connected to the associated motors to demand the associated motors produce a demanded thrust, wherein a motor power output of each motor of the associated motors is independently controlled to produce the demanded thrust and to control a motor temperature of one or more of the associated motors.

Abstract: A method of increasing fuel capacity of a fuel tank. The method includes creating a new filling port in the fuel tank, wherein the new filling port is vertically higher than the original filling port, sealing the original filling port, and installing an expansion tank above a top of the fuel tank, wherein the expansion tank is configured to permit expansion of fuel in the fuel tank beyond a maximum fill level of the fuel tank.

Abstract: A hook system has a mount that includes a first sidewall comprising a concave profile on a longitudinal end of the first sidewall, a second sidewall laterally offset in a fixed location relative to the first sidewall and defining a channel therebetween, the second sidewall having a second concave profile on a longitudinal end of the second sidewall. The hook system also has a first pin structure extending between the first sidewall and the second sidewall and a connector. The connector has a third concave profile, the third concave profile being configured to receive the first pin structure therein. The hook system also includes a second pin structure extending through the connector, wherein each of the first concave profile and the second concave profile are configured to receive the second pin structure therein. The connector is configured to be at least partially received within the channel.