An unmanned aerial vehicle (UAV) for gas transport is disclosed. The UAV includes a fuselage enclosing a volume, and a gas reservoir enclosed within the fuselage, filling at least a majority of the volume. The gas reservoir is configured to receive and store a gas at a pressure no greater than 100 bar. The UAV also includes a propulsion system having at least one engine, each of the at least one engine coupled to a prop that is driven by the at least one engine using energy derived from the gas stored in the gas reservoir. The UAV also includes a control system communicatively coupled to the propulsion system and configured to operate the unmanned aerial vehicle to autonomously transport the gas. The UAV may have a footprint while on the ground, and the footprint of the UAV may be no larger than three standard parking spaces.

The present vertical lift vehicle system can include a single internal combustion engine, a single propeller, and a plurality of small ducts. The small ducts can connect to a single main duct acting as a combustion chamber, wherein the combustion chamber combines air from the small ducts with propane, wherein when ignited the contents of the main duct produce added thrust to the vehicle as it exits the main duct.

The present vertical lift vehicle system can include a single internal combustion engine, a single propeller, and a plurality of small ducts. The small ducts can connect to a single main duct acting as a combustion chamber, wherein the combustion chamber combines air from the small ducts with propane, wherein when ignited the contents of the main duct produce added thrust to the vehicle as it exits the main duct.

A propulsion system for an aircraft includes a gas turbine engine and a fuel tank, wherein the fuel includes at least a proportion of a sustainable aviation fuel—SAF—having a density between 90% and 98% of the density, ρ.sub.K, of kerosene and a calorific value between 101% and 105% the calorific value CV.sub.K, of kerosene. The engine includes a combustor; and a fuel pump arranged to supply a fuel thereto at an energy flow rate, C, the pump being arranged to output fuel at a volumetric flow rate, Q, the percentage of fuel passing through the pump not provided to the combustor being referred to as a spill percentage. The fuel include X % SAF, where X % is in the range from 5% to 100%, and has a density, ρ.sub.F, and a calorific value CV.sub.F. The propulsion system is arranged so: the fuel-change spill ratio, R.sub.s, of: $R_s=\frac{\mathrm{spill}\mathrm{percentage}\mathrm{at}\mathrm{cruise}\mathrm{using}\mathrm{kerosene}}{\mathrm{spill}\mathrm{percentage}\mathrm{at}\mathrm{cruise}\mathrm{using}\mathrm{the}\mathrm{fuel}\mathrm{with}X\%SAF}$ is equal to: $\frac{Q-\left(C/\left({\mathrm{CV}}_K\times {\rho }_K\right)\right)}{Q-(C/({\mathrm{CV}}_F\times {\rho }_{}}$

A connection assembly between two portions of a line including an inner conduit for transporting a cryogenic fluid, the assembly including two flanges which are respectively arranged at the ends of the line portions and which are configured to be held in contact with one another by virtue of a fixing arrangement. The contact zone between the two flanges includes at least two grooves for positioning seals and at least one conduit opening out, for the one part, between the two seals and, for the other part, into an expansion chamber for the cryogenic fluid. The expansion chamber is arranged in one, or in the vicinity of one, of the first connection flange and the second connection flange. The expansion chamber includes a detector for detecting the presence of the cryogenic fluid in the expansion chamber or a recess configured for the installation of such a detector.

A method of generating a maintenance schedule for an aircraft including one or more gas turbine engines powered by an aviation fuel. The method includes: determining one or more fuel characteristics of the fuel; and generating a maintenance schedule according to the one or more fuel characteristics. Also disclosed is a method of maintaining an aircraft, a maintenance schedule generation system and an aircraft.

In order to enlarge a tank volume of a hydrogen powered aircraft, an aircraft tank for storing cryogenic H.sub.2 is configured as a non-circular dorsal tank. The aircraft tank may be configured as a conformal fuel tank fitted to an outer contour of an aircraft fuselage. Further, an aircraft is provided with such an aircraft tank.

In order to enlarge a tank volume of a hydrogen powered aircraft, an aircraft tank for storing cryogenic H.sub.2 is configured as a non-circular dorsal tank. The aircraft tank may be configured as a conformal fuel tank fitted to an outer contour of an aircraft fuselage. Further, an aircraft is provided with such an aircraft tank.

Aircraft having at least one propulsion unit supplied with hydrogen by at least one hydrogen tank, and having at least one thrust reversal system including at least one actuator. The aircraft can include at least one means for storing or transporting the residual hydrogen of the propulsion unit, a fuel cell disposed in the hydrogen power source and supplied with hydrogen by the at least one means for storing the residual hydrogen, and a hydrogen thrust reverser actuation system. The thrust reverser actuation system can include a hydrogen thrust reverser actuation controller and a hydrogen primary power unit with a fuel cell supplied with hydrogen and powering the at least one thrust reverser actuator.

Aircraft having at least one propulsion unit supplied with hydrogen by at least one hydrogen tank, and having at least one thrust reversal system including at least one actuator. The aircraft can include at least one means for storing or transporting the residual hydrogen of the propulsion unit, a fuel cell disposed in the hydrogen power source and supplied with hydrogen by the at least one means for storing the residual hydrogen, and a hydrogen thrust reverser actuation system. The thrust reverser actuation system can include a hydrogen thrust reverser actuation controller and a hydrogen primary power unit with a fuel cell supplied with hydrogen and powering the at least one thrust reverser actuator.