In accordance with at least on aspect of this disclosure, there is provided a hydrogen fuel system for aircraft. The hydrogen fuel system includes a gas turbine engine and a fuel feed conduit. The fuel feed conduit is defined at least in part by, in fluid series, a liquid hydrogen tank fluidly connected to a combustor of the gas turbine engine, a liquid hydrogen pump to drive fuel to the combustor of the gas turbine engine, an evaporator, and an electric heat source in thermal communication with the evaporator to add heat into a flow of hydrogen passing through the evaporator. In embodiments, the electric energy source associated with the electric heat source to power the electric heat source.

In accordance with at least one aspect of this disclosure, there is provided a method of accelerating a gas turbine engine. The method includes adding torque to a core of the gas turbine engine to accelerate rotation of the core by controlling fuel flow to a plurality of fuel injectors of the gas turbine engine. The method also includes adding torque to the core by powering an electric machine that is operatively connected to the core. In embodiments, controlling fuel flow to the plurality of fuel injectors is based on feedback from the electric machine.

In accordance with at least one aspect of this disclosure, there is provided a method of accelerating a gas turbine engine. The method includes adding torque to a core of the gas turbine engine to accelerate rotation of the core by controlling fuel flow to a plurality of fuel injectors of the gas turbine engine. The method also includes adding torque to the core by powering an electric machine that is operatively connected to the core. In embodiments, controlling fuel flow to the plurality of fuel injectors is based on feedback from the electric machine.

In accordance with at least one aspect of this disclosure, there is provided a drive shaft system. In embodiments, the drive shaft system includes a generator shaft extending along a longitudinal axis with a longitudinal bore defined through the generator shaft. A thru shaft extends through the longitudinal bore of the generator shaft. In embodiments, the thru shaft includes, a front coupler mount at a first end operative to receive torque input, and a rear coupler mount at a second end opposite the first end.

In accordance with at least one aspect of this disclosure, there is provided a drive shaft system. In embodiments, the drive shaft system includes a generator shaft extending along a longitudinal axis with a longitudinal bore defined through the generator shaft. A thru shaft extends through the longitudinal bore of the generator shaft. In embodiments, the thru shaft includes, a front coupler mount at a first end operative to receive torque input, and a rear coupler mount at a second end opposite the first end.

A conductive concrete electric thermal battery includes conductive concrete; and a plurality of electrodes disposed in the conductive concrete, each electrode of the plurality of electrodes is mechanically isolated from every other electrode of the plurality of electrodes and configured to connect electrically to a source of electrical energy. The conductive concrete includes a mixture of concrete and at least one conductive material.

A conductive concrete electric thermal battery includes conductive concrete; and a plurality of electrodes disposed in the conductive concrete, each electrode of the plurality of electrodes is mechanically isolated from every other electrode of the plurality of electrodes and configured to connect electrically to a source of electrical energy. The conductive concrete includes a mixture of concrete and at least one conductive material.

A compressor wheel is provided for the output shaft. Air bleed ports are formed in a shroud case that surrounds the compressor wheel. A plurality of air bleed passages are formed in the engine housing that surrounds the shroud case. An annular chamber is formed between the air bleed ports and the air bleed passages, for storing compressed air that is extracted from the air bleed ports.

A turbo device provides a flow-path arrangement in a generator device. Part of a working fluid are used to lubricate at least one of a first bearing part, a second bearing part and a bearing assembly, or the working fluid of an auxiliary flow channel is led to a generator housing for cooling the generator device. In addition, a circulatory system is also provided to include bearing loops and auxiliary loops for leading the working fluid to lubricate at least one of the first bearing part, the second bearing part and the bearing assemble part, and to cool the generator device.

A method for managing the offtake of power produced by an auxiliary power unit of an aircraft. The method comprises a step of calculating a maximum capacity for offtake of mechanical power that the auxiliary power unit can provide to the aircraft, a step of determining an actual offtake of mechanical power taken off by a first mechanical power offtake system of the auxiliary power unit, a step of comparing the maximum capacity for offtake of mechanical power and the actual offtake of mechanical power, a step of optimizing the offtake of mechanical power which step, based on the comparison of the maximum capacity for offtake of mechanical power and the actual offtake of mechanical power, determines at least one corrective action. A device for managing the offtake of power produced by an auxiliary power unit of an aircraft and an aircraft including such a device are provided.