Abstract: A flow control device on a structure such that strain in the structure is at least partially transferred to the flow control device is disclosed having at least two states, or shapes, separated by an elastic instability region. The flow control device is arranged to rapidly transition, or snap through, from the first state to the second state when strain in the structure exceeds an activation threshold of the flow control device. A spoiler on an aerofoil has a rest position where it is substantially flush with the low pressure surface and an activated position where it protrudes from the low pressure surface and modifies the airflow over that surface. The spoiler bends to move from the rest position to the activated position when the strain in the aerofoil crosses a threshold. The deployed spoiler reduces the lift on the aerofoil, acting to reduce the lift induced strain of the aerofoil to which the spoiler is attached.

Abstract: An aircraft wing is disclosed including a closed surface wing tip device which includes an element or actuator within the wing tip for deforming/morphing the shape of the wing tip between geometrical configurations having different aerodynamic properties, for example including one with better overall fuel efficiency for a shorter journey and one with overall fuel efficiency better suited for a longer journey. The device includes a lower winglet with an essentially planar portion spaced apart from the main body of the wing by a blended transition region which is shaped such that the curvature of the local dihedral increases in the outboard direction. The device includes an upper aerofoil structure which with the winglet essentially forms the closed surface. There is also disclosed an aircraft wing tip device having a sigmoid shaped (e.g. S-shaped) aerofoil structure blending in with a main wing of the aircraft.

Abstract: A flow control device on a structure such that strain in the structure is at least partially transferred to the flow control device is disclosed having at least two states, or shapes, separated by an elastic instability region. The flow control device is arranged to rapidly transition, or snap through, from the first state to the second state when strain in the structure exceeds an activation threshold of the flow control device. A spoiler on an aerofoil may have a rest position where it is substantially flush with the low pressure surface and an activated position where it protrudes from the low pressure surface and modifies the airflow over that surface. The spoiler bends to move from the rest position to the activated position when the strain in the aerofoil crosses a threshold. The deployed spoiler reduces the lift on the aerofoil, acting to reduce the lift induced strain of the aerofoil to which the spoiler is attached.

Abstract: A flow control device on a structure such that strain in the structure is at least partially transferred to the flow control device is disclosed having at least two states, or shapes, separated by an elastic instability region. The flow control device is arranged to rapidly transition, or snap through, from the first state to the second state when strain in the structure exceeds an activation threshold of the flow control device. A spoiler on an aerofoil may have a rest position where it is substantially flush with the low pressure surface and an activated position where it protrudes from the low pressure surface and modifies the airflow over that surface. The spoiler bends to move from the rest position to the activated position when the strain in the aerofoil crosses a threshold. The deployed spoiler reduces the lift on the aerofoil, acting to reduce the lift induced strain of the aerofoil to which the spoiler is attached.

Abstract: An aircraft wing is disclosed including a closed surface wing tip device which includes an element or actuator within the wing tip for deforming/morphing the shape of the wing tip between geometrical configurations having different aerodynamic properties, for example including one with better overall fuel efficiency for a shorter journey and one with overall fuel efficiency better suited for a longer journey. The device includes a lower winglet with an essentially planar portion spaced apart from the main body of the wing by a blended transition region which is shaped such that the curvature of the local dihedral increases in the outboard direction. The device includes an upper aerofoil structure which with the winglet essentially forms the closed surface. There is also disclosed an aircraft wing tip device having a sigmoid shaped (e.g. S-shaped) aerofoil structure blending in with a main wing of the aircraft.

Abstract: A panel assembly comprising: a panel (11); a stiffener (12) having a foot (12a), an upstanding web (12b) and a run-out region at one end; and a fitting (13), wherein the stiffener foot is bonded to the panel, and wherein the fitting is attached to the stiffener web and to the panel outboard of the end of the stiffener foot. The outboard end of the web may overhang an outboard end of the foot in the run-out region, of the stiffener.

Abstract: A method of manufacturing a composite structural member including laying up a stack of fiber reinforced laminate plies, wherein at least one of the plies is laid up as discrete first and second ply portions, and the fibers of the second portion have a different characteristic from those of the first portion. Also, a composite structural member manufactured according to the method.

Abstract: A composite structure including a panel and a stringer bonded to the surface of the panel, the stringer having an end surface and a pair of sides extending lengthwise along the stringer away from the end surface. The surface of the panel is formed with a first wall which engages the end surface of the stringer and a second wall which engages another part of the stringer. Compressive forces are transmitted from the panel to the stringer by a normal reaction between the first wall formed in the surface of the panel and the end surface of the stringer. Tensile forces are transmitted from the panel to the stringer by a normal reaction between the second wall formed in the surface of the panel and the other surface of the stringer.

Abstract: A method of manufacturing a composite structural member including laying up a stack of fiber reinforced laminate plies, wherein at least one of the plies is laid up as discrete first and second ply portions, and the fibers of the second portion have a different characteristic from those of the first portion. Also, a composite structural member manufactured according to the method.

Abstract: A joint between a pair of aircraft components comprising a first component; a second component bonded to the first component over a bonded area, the bonded area terminating at an edge; a non-bonded area located between the edge of the bonded area and an edge of the second component, the components not being bonded over the non-bonded area; and one or more fasteners passing through the non-bonded area and fastening the first component to the second component.

Abstract: A method of manufacturing a composite structural member (1), comprising the step of laying up a stack of fiber reinforced laminate plies (12), wherein at least one of the plies is laid up as discrete first (13) and second ply (14) portions, and the fibers of the second portion (14) have a different characteristic from those of the first portion (13). Also, a composite structural member (1) manufactured according to the method.

Abstract: A panel assembly comprising: a panel (11); a stiffener (12) having a foot (12a), an upstanding web (12b) and a run-out region at one end; and a fitting (13), wherein the stiffener foot is bonded to the panel, and wherein the fitting is attached to the stiffener web and to the panel outboard of the end of the stiffener foot. The outboard end of the web may overhang an outboard end of the foot in the run-out region, of the stiffener.

Abstract: A composite structure comprising: a first stack comprising a plurality of plies of composite material and at least one ply of self-healing material, the ply of self-healing material comprising a plurality of containers each containing a curable healing liquid; and a second stack comprising a plurality of plies of composite material, the stacks being joined together at a bond line. By placing a ply of self-healing material in one of the stacks (preferably relatively close to the bond line) the ply of self-healing material can resist the propagation of cracks between the first stack and the second stack. Preferably the global strength of the first stack is greater than the global strength of the second stack.

Abstract: A method of manufacturing a composite structural member (1), comprising the step of laying up a stack of fibre reinforced laminate plies (12), wherein at least one of the plies is laid up as discrete first (13) and second ply (14) portions, and the fibres of the second portion (14) have a different characteristic from those of the first portion (13). Also, a composite structural member (1) manufactured according to the method.

Abstract: A reinforced panel (1) comprising: a composite skin (2); a plurality of stringers (3, 4) bonded to the skin; and one or more strain actuators (5), each positioned between an adjacent pair of stringers. A load is applied to the panel in the plane of the skin, and a local strain is applied to the skin by the strain actuators when the compressive load exceeds a predetermined threshold. This causes the skin to buckle and reduce interface stresses between the skin and the stringers.

Abstract: A joint between a pair of aircraft components comprising a first component; a second component bonded to the first component over a bonded area, the bonded area terminating at an edge; a non-bonded area located between the edge of the bonded area and an edge of the second component, the components not being bonded over the non-bonded area; and one or more fasteners passing through the non-bonded area and fastening the first component to the second component.

Abstract: A composite structure comprising: a first stack comprising a plurality of plies of composite material and at least one ply of self-healing material, the ply of self-healing material comprising a plurality of containers each containing a curable healing liquid; and a second stack comprising a plurality of plies of composite material, the stacks being joined together at a bond line. By placing a ply of self-healing material in one of the stacks (preferably relatively close to the bond line) the ply of self-healing material can resist the propagation of cracks between the first stack and the second stack. Preferably the global strength of the first stack is greater than the global strength of the second stack.

Abstract: A reinforced panel (1) comprising: a composite skin (2); a plurality of stringers (3, 4) bonded to the skin; and one or more strain actuators (5), each positioned between an adjacent pair of stringers. A load is applied to the panel in the plane of the skin, and a local strain is applied to the skin by the strain actuators when the compressive load exceeds a predetermined threshold. This causes the skin to buckle and reduce interface stresses between the skin and the stringers.

Abstract: A composite structure which may form, for example, the skin of an aircraft wing or fuselage comprises a panel (20) and a series of stringers (21-23) bonded to the surface of the panel (20). Each stringer comprises a web (24) extending at right angles to the panel (20) and a pair of flanges (25, 26) which are coplanar with the panel. The web (24) is tapered at the run-out in order to facilitate load transfer from the skin to the stringer, by providing a gradual increase in transverse bending and axial stiffness and relieving local stress concentrations. XA pad (27) protrudes downwardly from the base of the stringer (22) and extends beyond the ends of the web (24) and flanges (25, 26). The pad (27) is embedded in a recess in the panel. The recess has a right-hand end wall (30) and a left-hand end wall (31). The walls (30, 31) are oriented in substantially opposite directions, and extend across the width of the stringer substantially at right angles to its length.