Abstract: 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.

Abstract: In accordance with at least one aspect of this disclosure, there is provided a system for aircraft power. The system includes a DC/DC converter having a DC input and a DC output and a switching circuit connecting the DC input to the DC output operable to vary voltage at the DC output. A control module is operatively connected to the switching circuit for variable control of the DC output. The control module includes machine readable instructions to cause the control module to receive input indicative of altitude and control the switching circuit to vary voltage of the DC output as a function of environmental conditions such as altitude and humidity. In embodiments the altitude sensor is operatively connected to the controller.

Abstract: A gas turbine engine has: a casing; a combustor liner delimiting a combustion chamber; a fuel nozzle in fluid communication with the combustion chamber; and an igniter having a base, a glow plug heater rod extending from the base along an axis and terminating in a rod end, and a sleeve extending around the glow plug heater rod, the sleeve radially spaced apart from the glow plug heater rod by an annular gap, the sleeve defines fins circumferentially distributed around the axis, each two circumferentially adjacent fins of the fins spaced apart from one another by a spacing communicating with the annular gap, the fins extending in a direction having an axial component from roots to tips, the roots axially closer to the base than the tips, the rod end extending axially beyond the tips of the fins such that the rod end is located outside the annular gap.

Abstract: There is disclosed an igniter for a gas turbine engine including: a base, a glow plug heater rod extending from the base along an axis and terminating in a rod end, and a plurality of fins disposed circumferentially around the glow plug heater rod, the fins extending axially along at least a portion of the glow plug heater rod. A gas turbine engine including such an igniter is further disclosed.

Abstract: There is disclosed an igniter for a gas turbine engine including: a base including a securing assembly configured to be matingly connected to a casing of the gas turbine engine, a glow plug heater rod, the glow plug heater rod extending from the base along an axis and terminating in a rod end, a flow impeding member extending along the axis and having a distal end spaced from the base and extending axially relative to the axis beyond the rod end, the flow impeding member sized and configured such that the distal end extends into a combustion chamber of the gas turbine engine upon the base connected to the casing.

Abstract: There is disclosed an igniter for a gas turbine engine including: a base; an inner conductor extending along an axis from the base to an end; a resistive heating element electrically connected to the end of the conductor; an outer conductor being electrically connected to the heating element, the outer conductor surrounding and extending axially along the inner conductor and forming a return electrical path, the outer conductor being radially spaced apart from the inner conductor by a gap, and an electrical insulator in the gap.

Abstract: There is disclosed an igniter for a gas turbine engine including: a base, a glow plug heater rod, the heater rod extending from the base along an axis and terminating in a rod end, a peripheral wall extending circumferentially around the rod end and having a distal end directed away from the base, a gap between the peripheral wall and the heater rod, the rod end being axially retracted relative the distal end of the peripheral wall.

Abstract: There is disclosed a method of servicing a gas turbine engine having a spark plug igniter connected to a spark plug igniter socket of the engine, the method including: removing the spark plug from the spark plug igniter socket of the gas turbine engine; inserting a glow plug igniter having a base configured for matingly engaging the spark plug igniter socket; and securing the glow plug igniter to the gas turbine engine.

Abstract: There is provided an igniter for a gas turbine engine including: a base, a glow plug heater rod extending from the base along an axis and terminating in a rod end, the heater rod having a heating section extending axially between axially opposite ends of a heater contained within the heater rod, a heat spreader being in thermal conduction contact with the heating section of the heater rod and extending radially therefrom.

Abstract: A hybrid electric aircraft propulsion system and method of operation are described. The system comprises a thermal engine, a generator coupled to the thermal engine, a first electric propulsor operatively connected to the generator to receive alternating current (AC) electric power therefrom, a second electric propulsor, a generator inverter operatively connected to the generator to convert AC electric power to direct current (DC) electric power, and a first motor inverter operatively connected to the generator inverter and selectively connected to one of the first electric propulsor and the second electric propulsor and configured to receive the DC electric power and provide the first electric propulsor and the second electric propulsor with AC electric power, respectively.

Abstract: A method for operating a glow plug includes controlling a temperature of the glow plug by switching between applying a voltage VH and applying a voltage VN<VH to the glow plug. Applying the voltage VH and applying the voltage VN causes a glow plug current to oscillate about a glow plug current threshold. The glow plug current threshold is associated with one of the voltage VH and the voltage VN. The method includes monitoring the glow plug current at the one of the voltage VH and the voltage VN.

Abstract: There are described methods and systems for operating a glow plug. The method comprises monitoring a glow plug current; applying a nominal voltage VN to the glow plug when the glow plug current is between an upper threshold I1 and a lower threshold I2<I1; applying a voltage VH>VN to the glow plug when the glow plug current exceeds the upper threshold I1; and applying substantially no voltage to the glow plug when the glow plug current falls below the lower threshold I2.

Abstract: A method of servicing a gas turbine engine having an igniter socket, the method comprising: inserting a glow plug into the igniter socket of the gas turbine engine until a rod end of a glow plug heater rod of the glow plug is exposed to a combustion chamber of the gas turbine engine; and blocking a gap between the glow plug heater rod and an aperture defined in a combustor liner of the gas turbine engine to block fluid communication between the combustion chamber and an environment outside the combustion chamber via the aperture.

Abstract: A battery system includes a plurality of battery cells abutting one another to form a battery cell stack. An optical communication link is connected to each of the plurality of battery cells. A battery management system (BMS) connected to the optical communication link configured and adapted to receive information from the optical communication link. A method of controlling heat transfer in a battery system includes monitoring at least one characteristic of at least one battery cell of a plurality of battery cells with at least one sensor, and sending information from the at least one sensor to a battery management system (BMS) with an optical communication link. The optical communication link is connected to each of the plurality of battery cells. The method includes selectively varying a fluid circulation rate in the battery system with the BMS depending on the at least one characteristic.

Abstract: A battery cell system includes a plurality of battery cells abutting one another to form a battery cell stack. The battery cell system includes a stack interface operatively connected to the battery cells wherein the stack interface includes a battery management system (BMS) and a mechanical switch device.

Abstract: A battery system comprising a plurality of stacks of battery cells. Each stack of battery cells has an annular shape. A main battery management system (BMS) operatively connected to at least one of the stacks of battery cells. The main BMS includes an annular housing and a motor drive assembly positioned within an inner diameter hole of the annular housing configured and adapted to drive circulation of a heat transfer fluid around the plurality of stacks.

Abstract: A battery cell system includes a plurality of battery cells abutting one another to form a battery cell stack. The battery cell system includes a stack interface operatively connected to the battery cells. The stack interface includes a housing defining a center and an outer perimeter. The stack interface includes a plurality of heat dissipating field effect transistors (FETs) arranged more proximate to the outer perimeter than the center.

Abstract: There is disclosed an igniter for a gas turbine engine including: a base including a securing assembly configured to be matingly connected to a casing of the gas turbine engine, a glow plug heater rod extending from the base along an axis to a rod end distal from the base, the glow plug heater rod sized such that that the rod end is exposed to a combustion chamber of the gas turbine engine when the base is connected to the casing.

Abstract: A hybrid electric aircraft propulsion system and method of operation are described. The system comprises a thermal engine, a generator coupled to the thermal engine, a first electric propulsor operatively connected to the generator to receive alternating current (AC) electric power therefrom, a second electric propulsor, a generator inverter operatively connected to the generator to convert AC electric power to direct current (DC) electric power, and a first motor inverter operatively connected to the generator inverter and selectively connected to one of the first electric propulsor and the second electric propulsor and configured to receive the DC electric power and provide the first electric propulsor and the second electric propulsor with AC electric power, respectively.

Abstract: There is disclosed an igniter for a gas turbine engine including: a base, a glow plug heater rod, the glow plug heater rod extending from the base along an axis and terminating in a rod end, a sleeve extending circumferentially around the glow plug heater rod along at least a portion of a length of the glow plug heater rod, the sleeve having an inner surface spaced from the glow plug heater rod to provide a gap between the inner surface and the glow plug heater rod, the gap extending radially relative to said axis.