Abstract: A battery system includes a plurality of battery modules each formed from a plurality of battery cells. A shared cooling structure is thermally coupled to each of the battery modules. The shared cooling structure is configured to conduct heat relative to the battery modules. A thermal interface is disposed between the battery cells of each battery module and the shared cooling structure. Each thermal interface is configured to transition from a first thermal conductivity state to a second thermal conductivity state when heat generated by the respective battery cells exceeds a threshold level. The second thermal conductivity state is lower than the first thermal conductivity state such that after one of the thermal interfaces has transitioned from the first thermal conductivity state to the second thermal conductivity state, heat transfer from the respective battery cells to the shared cooling structure is reduced.

Abstract: A battery system includes a plurality of battery modules each formed from a plurality of battery cells. A shared cooling structure is thermally coupled to each of the battery modules. The shared cooling structure is configured to conduct heat relative to the battery modules. A thermal interface is disposed between the battery cells of each battery module and the shared cooling structure. Each thermal interface is configured to transition from a first thermal conductivity state to a second thermal conductivity state when heat generated by the respective battery cells exceeds a threshold level. The second thermal conductivity state is lower than the first thermal conductivity state such that after one of the thermal interfaces has transitioned from the first thermal conductivity state to the second thermal conductivity state, heat transfer from the respective battery cells to the shared cooling structure is reduced.

Abstract: A rotorcraft main rotor system, including a yoke, a rotor blade, and a grip assembly attaching the rotor blade to the yoke. The grip assembly includes a grip body formed from a contiguous laminated composite and has a substantially constant thickness, where the grip body has an upper extension, a lower extension and a connecting portion connected between an inboard end of the upper extension and an inboard end of the lower extension. An inside surface of the upper extension faces, and is substantially parallel to, an inside surface of the lower extension, and the upper extension has first features and the lower extension has second features that are aligned with the first features, where the first features and second features each include at least one of an edge contour, attachment holes, or first protective elements.

Abstract: An example of a hub for a tail rotor includes a body configured to couple to a mast of a rotor system, a trunnion disposed within the body, first and second shafts disposed on opposite sides of the trunnion, first and second end plates secured to the body, and first and second end bearings, the first end bearing disposed between the first shaft and the first end plate and the second end bearing disposed between the second shaft and the second end plate.

Abstract: A rotorcraft main rotor system, including a yoke, a rotor blade, and a grip assembly attaching the rotor blade to the yoke. The grip assembly includes a grip body formed from a contiguous laminated composite and has a substantially constant thickness, where the grip body has an upper extension, a lower extension and a connecting portion connected between an inboard end of the upper extension and an inboard end of the lower extension. An inside surface of the upper extension faces, and is substantially parallel to, an inside surface of the lower extension, and the upper extension has first features and the lower extension has second features that are aligned with the first features, where the first features and second features each include at least one of an edge contour, attachment holes, or first protective elements.

Abstract: An embodiment rotorcraft main rotor system, including a yoke, a rotor blade, and a grip assembly attaching the rotor blade to the yoke. The grip assembly includes a grip body formed from a contiguous laminated composite and has a substantially constant thickness, where the grip body has an upper extension, a lower extension and a connecting portion connected between an inboard end of the upper extension and an inboard end of the lower extension. An inside surface of the upper extension faces, and is substantially parallel to, an inside surface of the lower extension, and the upper extension has first features and the lower extension has second features that are aligned with the first features, where the first features and second features each include at least one of an edge contour, attachment holes, or first protective elements.

Abstract: A transmission tilt control device includes a transmission rotatably coupled to an airframe of a helicopter, a rotor mast coupled to the transmission, and an actuator coupled between the transmission and the airframe. The actuator being configured to rotate the transmission fore and aft about a tilt axis that is perpendicular to an axis of rotation of the rotor mast.

Abstract: An example of a hub for a tail rotor includes a body configured to couple to a mast of a rotor system, a trunnion disposed within the body, first and second shafts disposed on opposite sides of the trunnion, first and second end plates secured to the body, and first and second end bearings, the first end bearing disposed between the first shaft and the first end plate and the second end bearing disposed between the second shaft and the second end plate.

Abstract: An example of a hub for a tail rotor includes a body configured to couple to a mast of a rotor system, a trunnion disposed within the body, first and second shafts disposed on opposite sides of the trunnion, first and second end plates secured to the body, and first and second end bearings, the first end bearing disposed between the first shaft and the first end plate and the second end bearing disposed between the second shaft and the second end plate.

Abstract: An embodiment rotorcraft main rotor system, including a yoke, a rotor blade, and a grip assembly attaching the rotor blade to the yoke. The grip assembly includes a grip body formed from a contiguous laminated composite and has a substantially constant thickness, where the grip body has an upper extension, a lower extension and a connecting portion connected between an inboard end of the upper extension and an inboard end of the lower extension. An inside surface of the upper extension faces, and is substantially parallel to, an inside surface of the lower extension, and the upper extension has first features and the lower extension has second features that are aligned with the first features, where the first features and second features each include at least one of an edge contour, attachment holes, or first protective elements.

Abstract: An exemplary rotorcraft includes a power train with an engine coupled to a gearbox, a main rotor blade having a mast coupled to the power train, a control input linkage in communication between a pilot input device and the main rotor blade configured to communicate a control input force from the pilot input device to the main rotor blade, and a counterweight system in connection with the control input linkage and the power train to apply a centrifugal force to the control input linkage.

Abstract: An example of a hub for a tail rotor includes a body configured to couple to a mast of a rotor system, a trunnion disposed within the body, first and second shafts disposed on opposite sides of the trunnion, first and second end plates secured to the body, and first and second end bearings, the first end bearing disposed between the first shaft and the first end plate and the second end bearing disposed between the second shaft and the second end plate.

Abstract: An exemplary rotorcraft includes a power train with an engine coupled to a gearbox, a main rotor blade having a mast coupled to the power train, a control input linkage in communication between a pilot input device and the main rotor blade configured to communicate a control input force from the pilot input device to the main rotor blade, and a counterweight system in connection with the control input linkage and the power train to apply a centrifugal force to the control input linkage.

Abstract: A rotorcraft has a low density altitude flight mode and a high density altitude flight mode. The rotorcraft includes a turboshaft engine forming a gas path in sequence through an air inlet section, a compressor section, a combustor section, a turbine section and an exhaust section. A drive system is coupled to the engine and is operable responsive to rotation of at least a portion of the turbine section. A rotor is coupled to the drive system and is operable to receive torque and rotational energy therefrom. A fuel injection system supplies fuel to the combustor section. An oxidizer injection system and a coolant injection system are used to selectively inject an oxidizer and a coolant into the gas path when it is desired to operate the rotorcraft in the high density altitude flight mode, thereby increasing the altitude density ceiling of the rotorcraft for maneuvers including takeoffs and landings.

Abstract: A transmission tilt control device includes a transmission rotatably coupled to an airframe of a helicopter, a rotor mast coupled to the transmission, and an actuator coupled between the transmission and the airframe. The actuator being configured to rotate the transmission fore and aft about a tilt axis that is perpendicular to an axis of rotation of the rotor mast.

Abstract: A rotorcraft has a low density altitude flight mode and a high density altitude flight mode. The rotorcraft includes a turboshaft engine forming a gas path in sequence through an air inlet section, a compressor section, a combustor section, a turbine section and an exhaust section. A drive system is coupled to the engine and is operable responsive to rotation of at least a portion of the turbine section. A rotor is coupled to the drive system and is operable to receive torque and rotational energy therefrom. A fuel injection system supplies fuel to the combustor section. An oxidizer injection system and a coolant injection system are used to selectively inject an oxidizer and a coolant into the gas path when it is desired to operate the rotorcraft in the high density altitude flight mode, thereby increasing the altitude density ceiling of the rotorcraft for maneuvers including takeoffs and landings.