Abstract: A hydrogen storage tank for a hydrogen fueled aircraft. The tank has a wall made of layers of aerogel sections around a hard shell layer, sealed within a flexible outer layer, and having the air removed to form a vacuum. The periphery of each layer section abuts other sections of that layer, but only overlies the periphery of the sections of other layers at individual points. The wall is characterized by a thermal conductivity that is lower near its gravitational top than its gravitational bottom. The tank has two exit passageways, one being direct, and the other passing through a vapor shield that extends through the wall between two layers of aerogel. A control system controls the relative flow through the two passages to regulate the boil-off rate of the tank.

Abstract: A hydrogen fueled powerplant including an internal combustion engine that drives a motor-generator, and has a two-stage turbocharger, for an aircraft. A control system controls the operation of the motor-generator to maintain the engine at a speed selected based on controlling the engine equivalence ratio. The control system controls an afterburner, an intercooler and an aftercooler to maximize powerplant efficiency. The afterburner also adds power to the turbochargers during high-altitude restarts. The turbochargers also include motor-generators that extract excess power from the exhaust.

Abstract: A high-altitude aircraft powerplant including an engine, a two-stage turbocharger having an intercooler and an aftercooler, a cryogenic hydrogen fuel source, and a cooling system including a hydrogen heat exchanger. Aided by a ram-air cooler that cools a coolant to a near-ambient temperature, the heat exchanger is configured to heat the hydrogen using the coolant, and to cool the coolant to a temperature well below the ambient temperature during high-altitude flight. The intercooler and aftercooler use the sub-ambient temperature coolant, as does a separate sensor. The ram-air cooler includes a front portion and a rear portion. The cooling system includes three cooling loops which respectively incorporate only the front portion, only the rear portion, and both portions of the ram-air cooler.

Abstract: A hydrogen fueled powerplant including an internal combustion engine that drives a motor-generator, and has a two-stage turbocharger, for an aircraft. A control system controls the operation of the motor-generator to maintain the engine at a speed selected based on controlling the engine equivalence ratio. The control system controls an afterburner, an intercooler and an aftercooler to maximize powerplant efficiency. The afterburner also adds power to the turbochargers during high-altitude restarts. The turbochargers also include motor-generators that extract excess power from the exhaust.

Abstract: A high-altitude aircraft powerplant including an engine, a two-stage turbocharger having an intercooler and an aftercooler, a cryogenic hydrogen fuel source, and a cooling system including a hydrogen heat exchanger. Aided by a ram-air cooler that cools a coolant to a near-ambient temperature, the heat exchanger is configured to heat the hydrogen using the coolant, and to cool the coolant to a temperature well below the ambient temperature during high-altitude flight. The intercooler and aftercooler use the sub-ambient temperature coolant, as does a separate sensor. The ram-air cooler includes a front portion and a rear portion. The cooling system includes three cooling loops which respectively incorporate only the front portion, only the rear portion, and both portions of the ram-air cooler.

Abstract: A hydrogen fueled powerplant including an internal combustion engine that drives a motor-generator, and has a two-stage turbocharger, for an aircraft. A control system controls the operation of the motor-generator to maintain the engine at a speed selected based on controlling the engine equivalence ratio. The control system controls an afterburner, an intercooler and an aftercooler to maximize powerplant efficiency. The afterburner also adds power to the turbochargers during high-altitude restarts. The turbochargers also include motor-generators that extract excess power from the exhaust.