An aircraft stores cryogenic fuel in one or more fuel tanks inside the aircraft fuselage or at other appropriate positions on the aircraft, and stores non-cryogenic fuel in plural standard jet fuel tanks e.g., inside the aircraft wings. A controller controls selective routing of non-cryogenic fuel or cryogenic (e.g., hydrogen) fuel to dual fuel engines. In one operating mode, the dual fuel engines normally use the cryogenic hydrogen fuel as the main fuel, and reserve the non-cryogenic fuel for application to the dual fuel engines only on an exception basis, thereby providing cleaner and more environmentally friendly operation.

A cryogenic storage tank including a first metallic end piece having a first structured connection area on its outer surface, a second metallic end piece having a second structured connection area on its outer surface, a hollow body extending between the first structured connection area and the second structured area. The hollow body is formed of a fiber reinforced polymer-based composite, a first metallic clamp having a third structured connection area and a second metallic clamp having a fourth structured connection area. The hollow body is arranged between and in intimate contact with the first structured connection area of the first metallic end piece and with the third structured connection area of the first metallic clamp and is arranged between and in intimate contact with the second structured connection area of the second metallic end piece and with the fourth structured connection area of the second metallic clamp.

An aircraft comprises a hydrogen-fuelled propulsion system, a plurality of like generally cylindrical hydrogen storage tanks and a conveying system arranged to convey hydrogen from the hydrogen storage tanks to the hydrogen-fuelled propulsion system. The aircraft further comprises a fuselage having a cargo bay (502) including one or more (510A-G) of the plurality of hydrogen storage tanks, the longitudinal axes (511A-G) of the one or more hydrogen storage tanks within the cargo bay extending parallel to the longitudinal axis (501) of the fuselage and lying in one or more planes (595, 597) extending across the width dimension of the cargo bay. The hydrogen storage tanks within the cargo bay have a common aspect ratio R in the range 4.2 ≤ R ≤ 25.7, allowing the volume of space with the cargo bay occupied by stored hydrogen to be maximised or approximately maximised.

An aircraft comprises a hydrogen-fuelled propulsion system, a plurality of like generally cylindrical hydrogen storage tanks and a conveying system arranged to convey hydrogen from the hydrogen storage tanks to the hydrogen-fuelled propulsion system. The aircraft further comprises a fuselage having a cargo bay (502) including one or more (510A-G) of the plurality of hydrogen storage tanks, the longitudinal axes (511A-G) of the one or more hydrogen storage tanks within the cargo bay extending parallel to the longitudinal axis (501) of the fuselage and lying in one or more planes (595, 597) extending across the width dimension of the cargo bay. The hydrogen storage tanks within the cargo bay have a common aspect ratio R in the range 4.2 ≤ R ≤ 25.7, allowing the volume of space with the cargo bay occupied by stored hydrogen to be maximised or approximately maximised.

An assembly is provided for an engine. This engine assembly includes a fuel system, a sensor and a processing system. The fuel system includes a fuel source, an engine component and a fuel circuit configured to direct fuel from the fuel source to the engine component. The sensor is configured to provide sensor data indicative of a measured parameter of the fuel directed through the fuel circuit from the fuel source to the engine component. The processing system is configured to identify a fuel leak in the fuel system based on the sensor data. The fuel leak is identified when a measured value corresponding to the measured parameter of the fuel is less than an expected value corresponding to an expected parameter for the fuel directed through the fuel circuit from the fuel source to the engine component.

A method is provided for operating an aircraft system. During this method, an engine is operated using first fuel provided by a first fuel source. A fuel supply for the engine is switched between the first fuel source and a second fuel source, where the switching of the fuel supply includes shutting down the engine during aircraft flight. The engine is operated using second fuel provided by the second fuel source.

A method is provided for operating an aircraft system. During this method, an engine is operated using first fuel provided by a first fuel source. A fuel supply for the engine is switched between the first fuel source and a second fuel source, where the switching of the fuel supply includes shutting down the engine during aircraft flight. The engine is operated using second fuel provided by the second fuel source.

A turbine engine system includes aircraft systems including at least one hydrogen fuel tank, engine systems comprising a compressor section, a combustor section having a burner, and a turbine section, and a hydrogen fuel flow supply line configured to supply hydrogen fuel from the at least one hydrogen fuel tank into the burner for combustion. The turbine engine system has a bypass ratio between 5 to 20.

A turbine engine system includes aircraft systems including at least one hydrogen fuel tank, engine systems comprising a compressor section, a combustor section having a burner, and a turbine section, and a hydrogen fuel flow supply line configured to supply hydrogen fuel from the at least one hydrogen fuel tank into the burner for combustion. The turbine engine system has a bypass ratio between 5 to 20.

An aircraft with a multi-walled fuel tank and method of manufacturing is presented. The aircraft includes a blended wing body and a fuel tank attached to the blended wing body configured to store liquified gas fuel. The fuel tank includes an inner wall, outer wall, and interstitial volume in between that is filled with insulation. The interstitial volume includes a reflective film layer and a structural insulation layer.