Abstract: An unmanned aerial vehicle (UAV) has an air-cooled fuel cell, an air channel comprising a forward facing opening for receiving ram air and connected to the air-cooled fuel cell, and a passive ram air filtration system (PRAFS) configured to filter particulate matter from ram air received into the air channel via the opening.

Abstract: A fuel tank includes an outer wall and a compliant layer disposed within a space at least partially defined by the outer wall. An aircraft includes a fuel cell and a fuel tank having an outer wall and a compliant layer disposed within a space at least partially defined by the outer wall. A method of operating a fuel tank includes providing an external wall and disposing a compliant layer of material within a space of the fuel tank that is at least partially defined by the external wall.

Abstract: A method of operating an aircraft includes providing a fuel cell system to power the aircraft, providing an airflow path through the fuel cell system, sensing a change mass air flow rate supplied to a compressor of the fuel cell system, and at least one of adjusting a restriction of airflow entering the airflow path in response to the sensed change in mass air flow rate, adjusting a restriction of airflow exiting the airflow path in response to the sensed change in mass air flow rate, and adjusting an air scoop to gather a different amount of air into the airflow path. A method of operating an aircraft includes sensing a change in ambient pressure supplied to an airflow path and adjusting a restriction of airflow exiting the airflow path in response to a sensed change in ambient pressure.

Abstract: A stack fuel cell array featuring paired fuel-cell systems combined to generate 540 VDC for a rotorcraft. Power from the hydrogen-based fuel cells is provided to the rotorcraft. A rated electrical load of the rotorcraft helps determine how many paired fuel-cell systems are needed during any fuel-cell systems failures. Each of the paired fuel-cell systems is coupled to an electrical load of the rotorcraft. The system detects any fuel cell failures and removes other working fuel cells as needed to balance the electrical system.

Abstract: A fuel-cell system for powering an electrical load, the system having first and second fuel cells, each having a positive node and a negative node. The positive node of the second fuel cell is electrically coupled to the negative node of the first fuel cell, and the positive node of the first fuel cell and the negative node of the second fuel cell are electrically coupled to the electrical load. Each fuel cell is electrically coupled to the electrical load without a power converter.

Abstract: A tank has a body defining a chamber therein, the chamber is configured to store a gas at a pressure greater than atmospheric pressure, a first mounting element extending from the body, and a second mounting element extending from the body. The first mounting element and the second mounting element are configured for coupling to a first component of a vehicle and a second component of the vehicle, respectively, and the body is configured to carry a structural load between the first component and the second component when the first mounting element and the second mounting element are coupled thereto. The first component carries a propulsion device and the second component comprises at least one of a wing and a landing element. The tank further includes a stem having an orifice and the stem is configured for delivering the gas to the propulsion device through the orifice.

Abstract: A fuel-cell system at 540 VDC for powering an electrical load of a rotorcraft with a first fuel cell and a second fuel cell. Each fuel cell is configured identically and features a positive electrical node and a negative electrical node. Each fuel cell is configured to provide one half of the electrical load of the rotorcraft and one half of the voltage of the electrical load.

Abstract: A method of operating an aircraft includes providing a fuel cell system to power the aircraft, providing an airflow path through the fuel cell system, sensing a change mass air flow rate supplied to a compressor of the fuel cell system, and at least one of adjusting a restriction of airflow entering the airflow path in response to the sensed change in mass air flow rate, adjusting a restriction of airflow exiting the airflow path in response to the sensed change in mass air flow rate, and adjusting an air scoop to gather a different amount of air into the airflow path. A method of operating an aircraft includes sensing a change in ambient pressure supplied to an airflow path and adjusting a restriction of airflow exiting the airflow path in response to a sensed change in ambient pressure.

Abstract: A system and a method for autonomous hydrogen refueling of vertical lift aircraft using a landing pad with sensors, a hydrogen storage tank, a refueling arm configured to couple the hydrogen storage tank to the aircraft and a controller configured to control a flow of fuel from the hydrogen storage tank to the aircraft.

Abstract: An aircraft that includes a fuselage, an electric motor driven propulsion system, and a fuel cell system configured to provide electricity to the electric motor. The fuel cell system includes a fuel cell, a hydrogen tank, an oxygen tank, an air channel, and a cathode switch. The cathode switch being configured to convert between an air mode, wherein the fuel cell operates utilizing air from the air channel, and an oxygen mode, wherein the fuel cell operates utilizing oxygen from the oxygen tank.

Abstract: An electric-powered aircraft battery pack and associated battery pack cooling system. The battery pack comprises a plurality of thermally conductive cooling plates and at least one battery cell coupled with each cooling plate. Heat generated by the battery cells is transferred by conduction to the associated cooling plate. The heat carried by the cooling plates is then transferred by convection to a fluid medium. In some embodiments, heat is transferred from the cooling plate to ambient air or ram air of the aircraft. In some embodiments, heat is transferred from the cooling plate to coolant liquid of a battery pack cooling system.

Abstract: A line-replaceable thrust module includes a nacelle configured to be mechanically connected to an anchoring location of an unmanned aerial vehicle (UAV), an electric motor coupled to the nacelle, an electric speed controller configured to control the speed of the electric motor and configured to be electrically connected to a communication network of the UAV, and a fuel cell system configured to produce electrical energy from an electrochemical reaction between hydrogen and oxygen. The fuel cell system includes a fuel cell, a hydrogen tank, a pressure regulator coupled to the hydrogen tank, and a supply line coupled between the pressure regulator and the fuel cell.

Abstract: An aircraft that includes a fuselage, an electric motor driven propulsion system, and a fuel cell system configured to provide electricity to the electric motor. The fuel cell system includes a fuel cell, a hydrogen tank, an oxygen tank, an air channel, and a cathode switch. The cathode switch being configured to convert between an air mode, wherein the fuel cell operates utilizing air from the air channel, and an oxygen mode, wherein the fuel cell operates utilizing oxygen from the oxygen tank.

Abstract: An unmanned aerial vehicle (UAV) has an air-cooled fuel cell, an air channel comprising a forward facing opening for receiving ram air and connected to the air-cooled fuel cell, and a passive ram air filtration system (PRAFS) configured to filter particulate matter from ram air received into the air channel via the opening.

Abstract: A system and a method for mobilized autonomous hydrogen refueling of vertical lift aircraft using a framed landing pad with sensors, an onboard hydrogen storage tank, an onboard refueling arm configured to couple the hydrogen storage tank to the aircraft and an onboard controller configured to control a flow of fuel from the hydrogen storage tank to the aircraft.

Abstract: A tank configured to store a pressurized gas therein and carry a structural load between components of a vehicle.

Abstract: A line-replaceable thrust module includes a nacelle configured to be mechanically connected to an anchoring location of an unmanned aerial vehicle (UAV), an electric motor coupled to the nacelle, an electric speed controller configured to control the speed of the electric motor and configured to be electrically connected to a communication network of the UAV, and a fuel cell system configured to produce electrical energy from an electrochemical reaction between hydrogen and oxygen. The fuel cell system includes a fuel cell, a hydrogen tank, a pressure regulator coupled to the hydrogen tank, and a supply line coupled between the pressure regulator and the fuel cell.

Abstract: A thermal management system includes a plurality of passages through a leading edge of a component of an aircraft. The thermal management system is configured to circulate coolant from a heat source through the plurality of passages in order to maximize heat transfer from the coolant to the airflow passing over the leading edge.

Abstract: A stack fuel cell array featuring paired fuel-cell systems combined to generate 540 VDC for a rotorcraft. Power from the hydrogen-based fuel cells is provided to the rotorcraft. A rated electrical load of the rotorcraft helps determine how many paired fuel-cell systems are needed during any fuel-cell systems failures. Each of the paired fuel-cell systems is coupled to an electrical load of the rotorcraft. The system detects any fuel cell failures and removes other working fuel cells as needed to balance the electrical system.

Abstract: A fuel-cell system at 540 VDC for powering an electrical load of a rotorcraft with a first fuel cell and a second fuel cell. Each fuel cell is configured identically and features a positive electrical node and a negative electrical node. Each fuel cell is configured to provide one half of the electrical load of the rotorcraft and one half of the voltage of the electrical load.