Abstract: An aircraft hydraulic control system includes a pump system, a fluid circuit, and a controller. The pump system includes a hydraulic pump and a ram air turbine assembly. The fluid circuit delivers hydraulic fluid to the hydraulic pump and receives the hydraulic fluid output from the hydraulic pump. The controller is in signal communication with the hydraulic pump. The controller determines a rotational frequency of a ram air turbine included in the ram air turbine assembly, and controls the hydraulic pump so as to control the flow of hydraulic fluid in the fluid circuit. The flow of hydraulic fluid in the fluid circuit controls a fluid pressure of the aircraft.

Abstract: A shaft system includes an outer shaft including an inner surface defining a conduit and an inner shaft extending within the conduit. The inner shaft includes a radially extending passage having a first end and a second end. A centrifugal force activated damper extends between the outer shaft and the inner shaft. The centrifugal force activated damper includes a first member arranged between the inner shaft and the inner surface at the first end of the radially extending passage, a second member arranged between the inner shaft and the inner surface at the second end of the radially extending passage, and a connecting member extending through the radially extending passage. Rotation of the shaft system causes the first member and the connecting member to shift away from the second member into the inner surface of the outer shaft.

Abstract: A shaft system includes an outer shaft including an outer surface and an inner surface defining a conduit and an inner shaft extending along at least a portion of the conduit. The inner shaft includes a radially extending passage. The inner shaft has a first end and a second end that is opposite the first end. An input member is arranged at the first end of the inner shaft. A thrust damper is arranged between the input member and the inner shaft. The thrust damper constrains relative rotation between the inner shaft and the outer shaft.

Abstract: An aircraft power system includes an auxiliary power unit (APU), a transmission unit, and a generator. The APU is configured to output a first APU rotational power in response to determining a first condition and a second APU rotational power in response to a determining a second condition. The transmission unit is configured to receive the first APU rotational output power from the APU. The transmission unit outputs a transmission rotational power based on the first APU rotational output power and outputs the transmission rotational power based on the second APU rotational output power. The generator receives the transmission rotational power and produces an alternating current (AC) voltage having a target frequency based on the transmission rotational power.

Abstract: An aircraft power system includes an auxiliary power unit (APU), a transmission unit, and a generator. The APU is configured to output a first APU rotational power in response to determining a first condition and a second APU rotational power in response to a determining a second condition. The transmission unit is configured to receive the first APU rotational output power from the APU. The transmission unit outputs a transmission rotational power based on the first APU rotational output power and outputs the transmission rotational power based on the second APU rotational output power. The generator receives the transmission rotational power and produces an alternating current (AC) voltage having a target frequency based on the transmission rotational power.

Abstract: An aircraft hydraulic control system includes a pump system, a fluid circuit, and a controller. The pump system includes a hydraulic pump and a ram air turbine assembly. The fluid circuit delivers hydraulic fluid to the hydraulic pump and receives the hydraulic fluid output from the hydraulic pump. The controller is in signal communication with the hydraulic pump. The controller determines a rotational frequency of a ram air turbine included in the ram air turbine assembly, and controls the hydraulic pump so as to control the flow of hydraulic fluid in the fluid circuit. The flow of hydraulic fluid in the fluid circuit controls a fluid pressure of the aircraft.

Abstract: A seal includes a carbon seal that is disposed about an axis and extends between a first axial end and a second axial end. The second axial end includes a seal surface and a radially outer edge of the seal surface is axially spaced from a radially inner edge of the seal surface along the axis.

Abstract: A torsion shaft assembly includes a torque carrying shaft including a driven end configured for receiving torque input to the torque carrying shaft and a driving end configured for outputting torque output from the toque carrying shaft. The torque carrying shaft includes an axial facing damping interface surface axially between the driven end and the driving end. A friction tube is disposed outboard of the torque carrying shaft. The friction tube is connected at a first axial location to be driven by the torque carrying shaft. The friction tube includes an axial facing damping interface surface that abuts the axial facing damping interface surface of the torque carrying shaft, forming a damping interface to provide frictional dampening against angular vibrations occurring as differential angular displacement between the driven end and the driving end of the torque carrying shaft.

Abstract: An aircraft power system includes an auxiliary power unit (APU), a generator, and a constant speed drive (CSD). The APU drives an APU drive shaft at a first rotational speed during a first condition and a second rotational speed during a second condition. The generator is rotatably coupled to a generator shaft and produces an AC voltage having a target frequency in response to rotation of the generator shaft at a target rotational speed. The CSD unit receives the first rotational speed from the APU drive shaft and rotates the generator shaft at the target rotational speed based on the first rotational speed. The CSD further receives the second rotational speed from the APU drive shaft and rotates the generator shaft at the target rotational speed based on the second rotational speed.

Abstract: A generator including a stator winding, a rotor positioned radially inside the stator winding, including multiple coil assemblies each using a flat wire, a primary termination plate residing radially inside the rotor configured to connect a wire of a coil assembly to an adjacent wound coil and a secondary termination plate residing radially inside the rotor configured to connect a wound coil to an adjacent wound coil and connect the wound coil to a terminus connection.

Abstract: A torsion shaft assembly includes a torque carrying shaft including a driven end configured for receiving torque input to the torque carrying shaft and a driving end configured for outputting torque output from the toque carrying shaft. The torque carrying shaft includes an axial facing damping interface surface axially between the driven end and the driving end. A friction tube is disposed outboard of the torque carrying shaft. The friction tube is connected at a first axial location to be driven by the torque carrying shaft. The friction tube includes an axial facing damping interface surface that abuts the axial facing damping interface surface of the torque carrying shaft, forming a damping interface to provide frictional dampening against angular vibrations occurring as differential angular displacement between the driven end and the driving end of the torque carrying shaft.

Abstract: A torsion shaft assembly includes a torque carrying shaft including a driven end configured for receiving torque input to the torque carrying shaft and a driving end configured for outputting torque output from the toque carrying shaft. The torque carrying shaft includes an axial facing damping interface surface axially between the driven end and the driving end. A friction tube is disposed outboard of the torque carrying shaft. The friction tube is connected at a first axial location to be driven by the torque carrying shaft. The friction tube includes an axial facing damping interface surface that abuts the axial facing damping interface surface of the torque carrying shaft, forming a damping interface to provide frictional dampening against angular vibrations occurring as differential angular displacement between the driven end and the driving end of the torque carrying shaft.

Abstract: A torsion shaft assembly includes a torque carrying shaft including a driven end configured for receiving torque input to the torque carrying shaft and a driving end configured for outputting torque output from the toque carrying shaft. The torque carrying shaft includes an axial facing damping interface surface axially between the driven end and the driving end. A friction tube is disposed outboard of the torque carrying shaft. The friction tube is connected at a first axial location to be driven by the torque carrying shaft. The friction tube includes an axial facing damping interface surface that abuts the axial facing damping interface surface of the torque carrying shaft, forming a damping interface to provide frictional dampening against angular vibrations occurring as differential angular displacement between the driven end and the driving end of the torque carrying shaft.

Abstract: A sealing assembly of an input shaft includes a support structure, a bearing assembly, and an input seal. The input seal including an input seal housing having a first portion and a second portion. The first portion is arranged adjacent the bearing assembly. At least one face plate anti-rotation pin is coupled to the input seal housing and positioned adjacent the input shaft. A face plate is positioned adjacent the second portion. The face plate is configured to directly contact the input shaft.

Abstract: A sealing assembly of an input shaft includes a support structure, a bearing assembly, and an input seal. The input seal including an input seal housing having a first portion and a second portion. The first portion is arranged adjacent the bearing assembly. At least one face plate anti-rotation pin is coupled to the input seal housing and positioned adjacent the input shaft. A face plate is positioned adjacent the second portion. The face plate is configured to directly contact the input shaft.

Abstract: A generator including a stator winding, a rotor positioned radially inside the stator winding, including multiple coil assemblies each using a flat wire, a primary termination plate residing radially inside the rotor configured to connect a wire of a coil assembly to an adjacent wound coil and a secondary termination plate residing radially inside the rotor configured to connect a wound coil to an adjacent wound coil and connect the wound coil to a terminus connection.

Abstract: A hybrid drive system can include a shaft, an electrical machine comprising a rotor and a stator, and a mechanical disconnect system connecting the rotor to the shaft. The mechanical disconnect system is configured to mechanically connect the rotor to the shaft in a first state and to mechanically disconnect the rotor from the shaft in a second state such that rotor does not drive the shaft or such that the rotor is not driven by the shaft. The rotor can be a permanent magnet rotor, for example.

Abstract: An integrated turbo-compressor includes a compressor with a compressor outlet, a turbine with a turbine inlet, the turbine operatively connected to the compressor by an interconnect shaft, and a compounding drive. The compounding drive is connected to the turbine and has a variable gear ratio and an output member, the variable gear ratio coupling the turbine to the output member to compound output of an internal combustion engine using energy recovered from an exhaust flow received from the internal combustion engine and in excess of energy required to compress combustion air provided to the internal combustion engine. Internal combustion engines, aircraft, and methods of compounding output of internal combustion engines are also described.

Abstract: A system for relieving pressure from within a generator casing can include a generator shaft defining a shaft channel therein and at least one rotating valve disposed within the shaft channel of the generator shaft and in fluid communication with an interior of the generator casing and the atmosphere. The rotating valve is configured to allow fluid within the generator casing to flow through the generator shaft to the atmosphere in an open state and while rotating. The rotating valve is configured to prevent fluid within the generator casing from flowing in a closed state.

Abstract: A hybrid drive system can include a shaft, an electrical machine comprising a rotor and a stator, and a mechanical disconnect system connecting the rotor to the shaft. The mechanical disconnect system is configured to mechanically connect the rotor to the shaft in a first state and to mechanically disconnect the rotor from the shaft in a second state such that rotor does not drive the shaft or such that the rotor is not driven by the shaft. The rotor can be a permanent magnet rotor, for example.