Abstract: The invention relates to a rotorcraft (21) comprising a fuselage (22) and an undercarriage (20) having skids (24, 25) interconnected by at least one cross-member (26, 27), together with connection means for connecting the cross-member to the fuselage and presenting angular stiffness that varies with varying sinking (E) of the undercarriage as a result of contact with the ground (23).

Abstract: A device for filtering vibration between two parts (2 and 3), includes: at least a first resilient plate (4) connected to the parts (2 and 3) at two respective fastener points at two respective points (2A and 3A), the first plate (4) being locally deformable under the action of vibration transmitted by one of the parts to the other part; and at least a first resonator (7) fitted with two laminated elastomer bearings (8, 9) receiving respective fastener elements (80, 90) fastening it to the first resilient member (4) in such a manner as to set the resonator (7) into oscillating pivoting motion in the event of the local deformation of the first resilient plate (4) such that the resonator (7) generates an anti-vibratory inertia torsor that opposes the vibration and filters transmission thereof from one part to the other.

Abstract: A steerable auxiliary nose undercarriage (2) for a rotary wing aircraft (1); the undercarriage (2) being retractable substantially rearwards. In the undercarriage (2), an oscillating system (13) presents a elevation stroke (58) about its hinged front end (52) that is greater than a shock absorbing stroke (59), and a shock-absorbing actuator (9) possesses retraction means for going beyond a high abutment position of the oscillating system (13) so that the oscillating system (13) and the shock-absorbing actuator (9) provide both a shock-absorption function and an undercarriage retraction function.

Abstract: A steerable auxiliary nose undercarriage (2) for a rotary wing aircraft (1); the undercarriage (2) being retractable substantially rearwards. In the undercarriage (2), an oscillating system (13) presents a elevation stroke (58) about its hinged front end (52) that is greater than a shock absorbing stroke (59), and a shock-absorbing actuator (9) possesses retraction means for going beyond a high abutment position of the oscillating system (13) so that the oscillating system (13) and the shock-absorbing actuator (9) provide both a shock-absorption function and an undercarriage retraction function.

Abstract: A rotary wing aircraft (1) such as a helicopter comprises a force-transmission structure (5) for transmitting forces, in particular those coming from an undercarriage (2), and that, in longitudinal elevation view, presents an L-shape in which the arrangement (6, 19-21) forms a transversely centered box (6), such that the structure (5) transfers the forces, at least in part, to top and bottom working covering segments of the fuselage.

Abstract: A steerable auxiliary nose undercarriage (2) for a rotary wing aircraft (1); the undercarriage (2) being retractable substantially rearwards. In the undercarriage (2), an oscillating system (13) presents a elevation stroke (58) about its hinged front end (52) that is greater than a shock absorbing stroke (59), and a shock-absorbing actuator (9) possesses retraction elements for going beyond a high abutment position of the oscillating system (13) so that the oscillating system (13) and the shock-absorbing actuator (9) provide both a shock-absorption function and an undercarriage retraction function.

Abstract: A device for filtering vibration between two parts (2 and 3), includes: at least a first resilient plate (4) connected to the parts (2 and 3) at two respective fastener points at two respective points (2A and 3A), the first plate (4) being locally deformable under the action of vibration transmitted by one of the parts to the other part; and at least a first resonator (7) fitted with two laminated elastomer bearings (8, 9) receiving respective fastener elements (80, 90) fastening it to the first resilient member (4) in such a manner as to set the resonator (7) into oscillating pivoting motion in the event of the local deformation of the first resilient plate (4) such that the resonator (7) generates an ant-vibratory inertia torsor that opposes the vibration and filters transmission thereof from one part to the other.

Abstract: The invention relates to a rotorcraft (21) comprising a fuselage (22) and an undercarriage (20) having skids (24, 25) interconnected by at least one cross-member (26, 27), together with connection means for connecting the cross-member to the fuselage and presenting angular stiffness that varies with varying sinking (E) of the undercarriage as a result of contact with the ground (23).

Abstract: A steerable auxiliary nose undercarriage (2) for a rotary wing aircraft (1); the undercarriage (2) being retractable substantially rearwards. In the undercarriage (2), an oscillating system (13) presents a elevation stroke (58) about its hinged front end (52) that is greater than a shock absorbing stroke (59), and a shock-absorbing actuator (9) possesses retraction elements for going beyond a high abutment position of the oscillating system (13) so that the oscillating system (13) and the shock-absorbing actuator (9) provide both a shock-absorption function and an undercarriage retraction function.

Abstract: A rotary wing aircraft (1) such as a helicopter comprises a force-transmission structure (5) for transmitting forces, in particular those coming from an undercarriage (2), and that, in longitudinal elevation view, presents an L-shape in which the arrangement (6, 19-21) forms a transversely centered box (6), such that the structure (5) transfers the forces, at least in part, to top and bottom working covering segments of the fuselage.

Abstract: The anti-vibration suspension device comprises at least three oblique bars, each articulated on the gearbox and on the structure by means of a rigid lever supporting an oscillating weight and in turn pivotally mounted by means of at least one pivot on this structure, and each lever is also joined to the gearbox by means of at least one torsion spring biassed about a torsion axis substantially perpendicular to the radial plane defined by the axes of the rotor and the corresponding oblique bar.

Abstract: The rotor comprises a hub 2 rotated with a mast 1 about an axis of the rotor ZZ, and each blade 3 is connected to the hub 2 by a member 5 on which the blade 3 is mounted so that the blade 3 can pivot about an axis of folding BB between a flight position and a folded-back position. The axis of folding BB is in a substantially radial plane passing through the axis of the rotor ZZ and is inclined with respect to this axis of the rotor ZZ so that it converges towards it, on the opposite side to the rotor mast 1. In automatic folding, the blade 3 is held in a fitting 6 pivoting on the member 5 about the axis of folding BB, whereas in manual folding, the blade 3 is held on the member 5 by two pins 8, one of which is removable to allow the blade to be folded about the other pin 8, the longitudinal axis of which is the axis of folding BB inclined in the radial plane.

Abstract: The invention relates to a helicopter fuselage of the type including a central structure to which are linked a front structure, a rear structure and a landing gear, and which supports a transmission gearbox, a main rotor and at least one engine (50), and of the type in which the central structure includes a skeleton (16) fitted with covering elements which define the external shape of the fuselage.According to the invention, the skeleton (16) of the central structure exhibits substantially the shape of a regular hexahedron consisting of skeleton panels (28, 30, 32, 34, 36, 38) assembled together.The invention finds an application especially for producing light helicopters.

Abstract: This invention relates to a rotorcraft rotor head which includes an even number of blades arranged in groups of two blades (2) which are diametrically opposed to each other, and linked to each other by a connection system without any link with the rotor hub. Each blade (2) is articulated in flapping and in pitch on the hub body (1) by a sleeve (3) which is arranged between the root of the blade (2) and the hub body (1). The sleeve (3) bears against the periphery of the hub body (1) by a laminated spherical stop (5) and includes an introduction member for controlling the pitch of the blade (2). Each system for connecting two diametrically opposed blades (2) is comprised of two tie rods (4) which link the two diametrically opposed sleeves (3) of the blades (2). The two tie rods (4) are arranged parallel to the plane of the rotor on either side of the longitudinal axis which is common to the two diametrically opposed blades ( 2).

Abstract: The present invention relates to a device for elastic connection between two components in order to transmit the static forces from one to the other in the axis of the device and to filter the associated vibratory excitations, comprising an elastic return mechanism (4) connected to a first and a second component and at least one swinging mass (5) located at one end of a lever arm, the lever arm articulated, in the vicinity of its other end, on the first and second components. The lever arm (6) consists of at least two portions (7, 8) articulated on one another, the first portion (7) being articulated on the first (2) and second (3) components in the vicinity of its end (7a) opposite that (7b) articulated on the second portion (8), and the second portion (8) being articulated, in the vicinity of its end (8a) articulated on the first portion (7), on the second component (3) and carrying the mass (5) at its opposite end (8 b).

Abstract: Landing gear for aerodynes and especially helicopters comprising two lateral members (2) for contact with the ground being linked to the fuselage of the aerodyne by at least two crosspieces (3, 4). These crosspieces (3, 4) are produced as a bundle (7) of unidirectional synthetic fibers sheathed by a skin (8) of tissues of fibers which are crossed with respect to the unidirectional fibers of the bundle (7). The extremities (9) of the crosspieces are embedded in the lateral members (2) for contact with the ground. The structural links between the crosspieces (3, 4) and the fuselage of the aerodyne (H) allow the pivoting of the crosspieces (3, 4) about transverse axes of the aerodyne (H).

Abstract: The invention relates to a drag elastic-return and damping device (28) for a blade, and a rotor head including it.The device (28) comprises a connecting rod (30) connected to the blade and transmitting its drag movements to a rotary member (29) for elastic return with incorporated damping whose outer armature (32) it causes to rotate about a coaxial inner armature (31) in order to shear at least one thin collar (33) of a viscoelastic elastomer about its axis (B). The connecting rod (30) is coupled by way of rotational joints (43, 44) to a sleeve (15) for attaching the blade to the hub (1), and to a lever (34) of the outer armature (32). The member (29) is supported at the periphery of the hub (1), between two adjacent blades, or in the sleeve for attaching an adjacent blade such that the corresponding connecting rod is mounted as an inter-blade tie. On the rotor head, each blade is articulated with the hub (1) by a spherical laminated thrust block (5).

Abstract: The invention relates to a device for reducing the damping flexibility of a suspension shock absorber for an undercarriage, in particular the main undercarriage of a helicopter, and a shock absorber and an undercarriage including it.The shock absorber is of the oleo-pneumatic type, and at least one of the incompressible and compressible fluids of the shock absorber is at least partially transferred from an expansion chamber (31) of the latter into a transfer chamber (42) of an accumulator (40) external to the shock absorber (1, 8), and in which the transfer chamber (42) is isolated from a return chamber (43) by a separating piston (41). The connection between the transfer chamber (42) and the corresponding expansion chamber (31) can be cut off by an electro-valve (44), in order to isolate the shock absorber (1, 8) from at least part of the low pressure gas chamber (34) of its expansion chamber (31).Application to the undercarriage equipment, in particular the main undercarriages of ship-borne helicopters.