In some examples, an aircraft comprises an airframe, a rotor system coupled to the airframe, and a vibration attenuation system. The rotor system is operable to exert a vibratory force on the airframe. The vibration attenuation system comprises two or more batteries and elastic devices. The two or more batteries are operable to supply power to the rotor system. The elastic devices coupled to the two or more batteries and the airframe. The elastic devices are configured to attenuate the vibratory force based on facilitating oscillation of the two or more batteries. In other examples, a method comprises coupling elastic devices to two or more batteries and an airframe of an aircraft. The elastic devices receiving a vibratory force via the airframe and attenuate the vibratory force based on facilitating oscillation of the two or more batteries.

A hybrid propulsion system includes a heat engine configured to drive a heat engine shaft. An electric motor is configured to drive an electric motor shaft. A transmission system includes at least one gearbox. The transmission system is configured to receive rotational input power from each of the heat engine shaft and the electric motor shaft and to convert the rotation input power to output power.

The present disclosure pertains to electric machines such as electric propulsion systems for aircraft that integrated cooling systems, and methods of cooling such an electric machine. Exemplary electric machines include an electric motor that has a stator, a rotor, and a drive shaft operably coupled to the rotor. Exemplary electric machines further include a motor cooling conduit that defines a pathway for conveying a cooling fluid through or around at least a portion of the electric motor, a casing assembly that circumferentially surrounds at least a portion of the electric motor, a casing assembly conduit integrally formed within at least a portion of the casing assembly which defines a pathway for conveying the cooling fluid through the at least a portion of the casing assembly, and a pump or compressor operably coupled to the drive shaft and configured to circulate the cooling fluid through the motor cooling conduit and the casing assembly conduit.

A gas turbine engine for an aircraft such as a UAV includes a compressor connected to a turbine with a combustor to produce a hot gas stream. The rotor is supported by two radial foil bearings. An axial thrust bearing assembly is positioned between the compressor disk and the turbine disk and includes an axial thrust bearing radial disk extending from a hollow axial tube. Compressed air is bled off from the compressor and passed into an axial thrust balance chamber to provide the axial thrust balance for the rotor. The compressed air from the thrust bearing chamber then flows through both of the radial foil bearings for cooling, is collected in and around the hollow tube, and then discharged into the inlet of the turbine. An orifice can be adjusted to meter and control a pressure occurring in the thrust balance chamber.

A hybrid-electric propulsion system for an aircraft is provided herein that can include a propulsor and a turbomachine comprising a high pressure turbine drivingly coupled to a high pressure compressor through a high pressure spool. An auxiliary power unit can be operably coupled with a starter motor. An electrical system can comprise a first electric machine coupled to the turbomachine. The first electric machine can be separate from the starter motor. A controller can be configured to provide electrical power from an electric power source to the first electric machine to drive the first electric machine to start, or assist with starting, the turbomachine.

This invention relates to electrically-driven propulsors for regional aircraft. These combine fans optimized for quiet regional operations with rotating variable pitch mechanisms contained within the hubs and highly efficient ring electric motors. The ring motors are used to drive annular fans at the inner or outer radius, or a conventional fan at the inner radius. The assembly combines a single fan, fixed or variable pitch, with a row of stators, or multiple counter-rotating fans without stators. Our focus is on propulsors optimized for quiet and efficient regional flights, but many elements apply to long-haul air and several other applications referred to herein.

An aeronautical propulsion system including a turbine engine having a fan and an electric motor drivingly coupled to at least one of the fan or the turbine engine. The aeronautical propulsion system additionally includes a fuel cell for providing electrical energy to the electric motor, the fuel cell generating water as a byproduct. The aeronautical portion system directs the water generated by the fuel cell to the turbine engine during operation to improve an efficiency of the aeronautical propulsion system.

A computer-implemented method, system, and/or computer program product optimizes an operation of an aerial drone. A drone on-board computer on an aerial drone receives sensor readings from sensors on the aerial drone, where the sensor readings detect a change in flight conditions while the aerial drone is flying between a first location and a second location. In response to the sensors on the aerial drone detecting a change in the flight conditions while the aerial drone is flying between the first location and the second location, the drone on-board computer disengages an electric motor from propellers on the aerial drone and engages an internal combustion engine to the propellers.

An aspect includes a battery charging system for a hybrid electric aircraft. The battery charging system includes a generator, a battery system, and a controller. The controller is operable to charge the battery system up to a first charge level based on receiving a first charging current at a power input. An operational status of a gas turbine engine of the hybrid electric aircraft is monitored. The battery system is charged at a second charging current received from the generator driven by the gas turbine engine responsive to determining that the gas turbine engine is in a taxi state, where the second charging current is less than the first charging current. Charging of the battery system is halted based on detecting a transition of the gas turbine engine from the taxi state to an off-idle throttle state.

An autonomous unmanned aerial vehicle for land, sea and air use. The autonomous unmanned aerial vehicle is more specifically related to an unmanned aerial vehicle, wherein the autonomous unmanned aerial vehicle is configured to vertically take off and vertically land, fly with fixed wings and stay in the air silently for a long time by means of a balloon inflated behind it.