Lightning protected vent lines associated operatively with aircraft fuselage fuel tanks (i.e., on-board fuel tanks that are not physically located in an aircraft's wing but instead are physically located within the aircraft's fuselage structure) are provided which include a vent conduit, a coupling at a proximal end of the vent conduit for fluid connecting the vent conduit to the fuel tank, a vent opening positioned at a distal end of the vent conduit and at an external location of the fuselage and a flame arrestor positioned in the conduit between the coupling and the vent opening. The vent conduit will have an effective axial dimension (L) between the coupling and the vent opening and the flame arrestor will be positioned in the conduit at an effective separation distance (D) between an inlet of the flame arrestor and the vent opening such that L/D is greater than 5. Alternatively, the flame arrestor may be omitted, but the vent conduit will then have at least one linear conduit segment to provide an effective axial dimension (L.sub.1) of the vent line conduit between the coupling and the vent opening which is at least ten times greater than the vent conduit diameter (D.sub.1).

A fuel tank or bladder-free fuel tank having a reservoir on its inside area, limited to an outside area by a double-walled structure. The double-walled structure has an outer wall and an inner wall. A rib structure includes at least one rib extending inwardly into the inside area of the bladder-free fuel tank from the double-walled structure.

A fuel tank or bladder-free fuel tank having a reservoir on its inside area, limited to an outside area by a double-walled structure. The double-walled structure has an outer wall and an inner wall. A rib structure includes at least one rib extending inwardly into the inside area of the bladder-free fuel tank from the double-walled structure.

A tank defines an inner cavity and at least an opening. A filler tube device comprises a tube passing through the opening in the tank, the tube forming a joint with at least one degree of freedom with the tank such that the tube is displaceable relative to the tank. The tube has an open end in the inner cavity of the tank, and an opposite open end outside of the tank, whereby the tube defines a passage for filling the tank. A sealing component is in the inner cavity of the tank, the sealing component configured for collaborating with the open end of the tube when the tube is moved into engagement therewith to close the open end of the tube inside the tank in a protective position.

A tank defines an inner cavity and at least an opening. A filler tube device comprises a tube passing through the opening in the tank, the tube forming a joint with at least one degree of freedom with the tank such that the tube is displaceable relative to the tank. The tube has an open end in the inner cavity of the tank, and an opposite open end outside of the tank, whereby the tube defines a passage for filling the tank. A sealing component is in the inner cavity of the tank, the sealing component configured for collaborating with the open end of the tube when the tube is moved into engagement therewith to close the open end of the tube inside the tank in a protective position.

A method of partially insulating an interior space of a pre-formed fluted core panel is disclosed herein. The fluted core panel includes a first facesheet, a second facesheet spaced apart from the first facesheet, and webs between the first facesheet and second facesheet. The interior space is defined between the first facesheet, the second facesheet, and adjacent webs. The method includes positioning a spacer in a first portion of the interior space, positioning a membrane between the spacer and a second portion of the interior space, and positioning insulation in the second portion of the interior space. Additionally, the method includes pressing the membrane against the spacer, curing the membrane, and removing the spacer from the first portion of the interior space.

A flexible fuel tank (10) has, from the inside to the outside of the tank: a single-layer or multilayer liner (2) having properties of sealing with respect to the liquid, impermeability to the vapor of said fuel, and dissipation of electrostatic charges. The liner (2) includes an inner face (2a) intended to be in contact with the fuel and an outer face (2b). An intermediate layer (3) is in contact with the outer face (2b) of the liner (2), for example a coating layer; and a textile reinforcing layer (4) is in contact with the intermediate layer (3).

A flexible fuel tank (10) has, from the inside to the outside of the tank: a single-layer or multilayer liner (2) having properties of sealing with respect to the liquid, impermeability to the vapor of said fuel, and dissipation of electrostatic charges. The liner (2) includes an inner face (2a) intended to be in contact with the fuel and an outer face (2b). An intermediate layer (3) is in contact with the outer face (2b) of the liner (2), for example a coating layer; and a textile reinforcing layer (4) is in contact with the intermediate layer (3).

A composite structure includes a first composite material, a second composite material bonded to the first composite material, and a corner fillet part provided at a corner part formed by the first composite material and the second composite material. In the composite structure, the rigidity of the corner fillet part is adjustable, and a pull-off stress to be applied to the corner part is adjusted by adjusting the rigidity of the corner fillet part. The pull-off stress to be applied to the corner part is adjusted to be decreased by adjusting the rigidity of the corner fillet part to be decreased.

A hydrogen-fuelled aircraft 200 comprises a fuselage, wings and a plurality of cylindrical elongate hydrogen storage tanks mounted on the exterior of the fuselage and disposed vertically above a plane containing the wing-tips of the aircraft. An aerodynamic fairing forms a continuous air-washed surface of the aircraft together with a lower portion of the fuselage. The hydrogen storage tanks extend generally parallel to the fuselage and are contained between the fairing and the fuselage. The aircraft provides for storage of a large volume of compressed hydrogen without compromising the volume of usable space within the fuselage. The aircraft is able to carry out flight missions comparable in range and payload to those of an equivalent conventionally-fuelled aircraft.