OBSTACLE FOR SECURING AN AIRCRAFT ON A LANDING GRID AND AIRCRAFT

Description

[0001] The present invention relates to a restraint for securing an aircraft on a landing grid and an aircraft equipped with such a restraint.

[0002] An aircraft may be placed on a moving surface or one exposed to wind, for example on a ship. The aircraft may then be equipped with a system enabling it to remain in a substantially stationary position regardless of the wind and / or, where applicable, the movement of the ship, and in particular its pitch and roll.

[0003] An anchor harpoon is typically mounted under the aircraft's fuselage, between the landing gear wheels or between the skids of a skid-type landing gear. The harpoon has a movable harpoon head. This head is equipped with a clamp, a finger, or other device that automatically locks into place upon landing on a platform's landing grid. Such a grid is sometimes referred to as a "landing grid" in the context of a ship.

[0004] Furthermore, the anchor harpoon, once anchored, applies a tensile force between the anchor point and the aircraft, thus securing the aircraft to the platform to increase its stability and ensure its retention. Within a certain range of ship heel and wind conditions, the anchor harpoon can therefore temporarily replace a mooring system.

[0005] An anchor harpoon includes a means of deploying the harpoon head allowing, on the one hand, the movement of the harpoon head during landing and, on the other hand, the application of a pulling force on the harpoon head in order to press the aircraft onto the platform.

[0006] The means of deploying the harpoon head generally includes a hydraulic cylinder, particularly on a medium or heavy aircraft requiring powerful harpoons, or an electric or even pneumatic cylinder on lighter aircraft.

[0007] An anchor harpoon is useful and effective, but can be relatively heavy since it is subjected to significant stress. Furthermore, its placement under the fuselage can sometimes be tricky when certain additional equipment is present, such as cameras, spotlights, or radar systems.

[0008] For example, documents FR 2 701 689 A1, FR 2 943 988 A1 and FR 2 982 241 A1 describe anchoring harpoons.

[0009] Document FR 2 701 689 A1 describes a harpoon having a harpoon head comprising a pin. The pin is equipped with radially oriented and movable fingers, means for engaging and retaining the fingers in the extended position, and means for unlocking the fingers.

[0010] Document FR 2 943 988 A1 describes a gas-operated anchor harpoon with a rod. One free end of the rod has a harpoon head equipped with retaining fingers that can be moved between a retracted and an active position by means of control.

[0011] Document FR 2 982 241 A1 describes a harpoon having a bistable actuator.

[0012] Document FR 2 708 249 A1 describes an adapter for a helicopter landing and takeoff assistance system. The adapter is equipped with an automatic anchoring head for use in a landing grid.

[0013] Document WO 91 / 04910 A1 describes a restraint device for restraining, for example, an aircraft on the deck of a ship. The restraint device comprises an articulated arm attached to an aircraft and two hydraulic cylinders. The arm includes an actuator that cooperates with a head. The head includes two hooks for clamping a separator of a landing grid, the separator being positioned between two slots.

[0014] Document FR 1 291 049 A describes a mooring device. The mooring device comprises a cylinder with a piston attached to a control rod. The mooring device has a head carried by the control rod. The head has a guide pin and two hooks.

[0015] Document FR 1 253 269 A describes a retractable screw restraint device for an aircraft. The screw is deployed before landing and rotated to be screwed into a platform lined with contiguous swivel nuts.

[0016] The purpose of this disclosure is therefore to propose not a harpoon that anchors itself to a landing grid, but a hindrance that is likely to be less complex and heavy than a harpoon in order to limit the slippage of a skidded aircraft.

[0017] The invention as claimed proposes an assembly according to claim 1. Other optional features are claimed in dependent claims 2-14.

[0018] This disclosure relates to an assembly with a restraint for an aircraft. This restraint comprises a cylinder including a housing and a head movable in translation relative to the housing along an elevation axis, said head having three degrees of freedom in rotation respectively about a longitudinal axis as well as a transverse axis and the elevation axis, for example relative to, among other things, an aircraft cell, said restraint comprising a force-retaining element surrounding the cylinder and provided with a fixing suitable for being secured to the aircraft.

[0019] The actuator can be electric, pneumatic, or hydraulic. It can typically be connected to a control interface to extend, if needed on the ground, or retract, particularly in flight.

[0020] From this point, the hydraulic cylinder can move the head of the obstacle translationally towards a standard landing grid after landing, engaging the head within the grid. Such a landing grid typically consists of cells and dividers separating adjacent cells. The three rotational degrees of freedom of the obstacle head then allow it to reach a stationary position, with the head penetrating at least partially into one or two cells by positioning itself on either side of a grid divider. Once the head is positioned within the landing grid, the force-response mechanism limits the cylinder's movement relative to the aircraft and transmits the forces to the aircraft at its limit. Consequently, the aircraft's movements relative to the landing grid are restricted.The head can have an immutable / fixed shape not comprising any parts moving relative to each other, unlike a head equipped with a clamp or at least one locking finger that moves in translation, for example.

[0021] Thus, an aircraft can be equipped with one or more restraints, each designed to limit the aircraft's slippage. Unlike a harpoon, these restraints exert no tensile force. Each restraint can therefore be compact and relatively lightweight, as the forces it experiences are directly absorbed by the aircraft.

[0022] Contrary to some misconceptions, it is not always necessary to use an anchor harpoon to provide traction. Depending on the type of aircraft, weather conditions, the characteristics of the vessel or floating deck, and sea state, this disclosure suggests using a restraint. An aircraft can be relatively stable on a ship's deck, at least during certain deck movements, particularly a relatively light aircraft and / or one with skids. Therefore, such a restraint may be sufficient under conditions of limited deck movement at sea. The restraint prevents the aircraft from sliding on the ship's deck, and the risk of tipping is negligible when deck movements are minimal.

[0023] The obstacle may also include one or more of the following characteristics, taken alone or in combination.

[0024] The restraint may include a support carrying said cylinder, the cylinder being movable in rotation relative to the support along the longitudinal axis and the transverse axis, the head being movable in rotation relative to the housing along the elevation axis.

[0025] For example, the support consists of a bearing connected by a joint to the cylinder. This simple configuration easily provides the head with the required mobility. The support can be lightweight since the radial forces experienced in case of sliding are transmitted through the load-bearing element.

[0026] According to a possibility compatible with the previous one, the head may include a free end comprising two stops adapted to / configured to jointly enter the same cell of a landing grid, said two stops being immobile relative to each other and separated from each other by a space adapted to accommodate a separator of said landing grid separating two said cells.

[0027] The head thus comprises two elongated elements forming two stops that create a fork. Therefore, the two stops are configured to jointly grip a separator by entering two recesses, and to be able to be inserted into the same recess.

[0028] According to a possibility compatible with the previous ones, the two stops can each include a tapered end section away from the housing.

[0029] During the extension of the cylinder, this feature promotes the rotation of the head relative to the landing grid to reach its immobilization position either in one or two cells around a separator, depending on the initial point of contact between the head and the landing grid.

[0030] According to a possibility compatible with the previous ones, at least one tapered end section can be rounded.

[0031] During the extension of the cylinder, this feature promotes the rotation of the head, relative to the landing grid, for its engagement in the landing grid, avoiding a blockage before a locking position is reached.

[0032] Depending on a possibility compatible with the previous ones, the two stops can be different.

[0033] During cylinder extension, this feature facilitates the rotation of the head relative to the landing grid, enabling it to engage with the grid and preventing it from jamming before reaching its final position. The head has an asymmetrical shape to prevent the cylinder from jamming if it is not correctly positioned. This asymmetrical shape may also influence the direction of rotation of the head.

[0034] According to a possibility compatible with the previous ones, one stop of said two stops can extend parallel to the axis in elevation over a first length and the other stop extends parallel to the axis in elevation over a second length greater than the first length.

[0035] During cylinder extension, this feature facilitates the rotation of the head relative to the landing grid, thus preventing it from engaging in the grid and avoiding jamming in a suboptimal position. This feature prevents the head from making contact with the landing grid simultaneously at two points and failing to reach a stationary position.

[0036] According to a possibility compatible with the previous ones, the said two stops may each include a rounded external face concave with respect to the axis in elevation, namely viewed from the axis in elevation.

[0037] The cells of a landing grid are usually cylindrical. Therefore, the external faces can have a shape complementary to the wall delimiting a cell to ensure optimal retention within a cell.

[0038] According to a possibility compatible with the previous ones, the two stops can each include a rounded internal face convex with respect to the axis in elevation, namely viewed from the axis in elevation.

[0039] The internal faces can be shaped to complement the walls of a separator to ensure optimal retention when the head is fitted around the separator. If applicable, this shape tends to facilitate the sliding of the head against the landing grid to reach a stationary position. The gap between the separator and the head can be minimized.

[0040] According to a possibility compatible with the previous ones, one stop of the two stops may have an oval shape in a plane orthogonal to the axis in elevation and the other stop has a truncated oval shape in said plane.

[0041] During the extension of the cylinder, this feature promotes the rotation of the head, relative to the landing grid, for its engagement in the landing grid.

[0042] This disclosure relates to an assembly comprising a landing grid with multiple cells, each cell being separated from an adjacent cell by a separator of the landing grid. This assembly includes a stop, the stops having a shape that can be inscribed within each cell, the space having a shape that can contain each separator.

[0043] This disclosure also relates to assembly with an aircraft having at least one such hindrance.

[0044] The aircraft having a landing gear, the attachment of the force-recovery device being secured to the landing gear or to a pole attached to a cell of the aircraft.

[0045] The restraint may include a support carrying the jack and the aircraft may include a landing gear, the support may be attached to the landing gear or to a pole attached to a cell of the aircraft.

[0046] Optionally, the restraint can be attached to the landing gear itself or to a pole fixed to an aircraft cell or to the landing gear, for example.

[0047] Unlike a harpoon, the restraint may not be positioned under the fuselage. Such an arrangement, particularly on the landing gear, can facilitate the deployment and / or removal of the restraint. This arrangement can also prevent obstructing access to the underside of the aircraft and / or the installation of other equipment, such as surveillance equipment like an optronic turret, spotlight, camera, or radar.

[0048] According to one possibility, the landing gear can be a skid landing gear, the attachment and support being able to be fixed to a skid of the landing gear, the support being able to have a joint carrying the jack, the joint being able to be located above the force-recovery element when the aircraft is on the ground.

[0049] The jack can be mounted on a ball joint or universal joint on the support to allow angular freedom of movement at least around the longitudinal and transverse axes. This joint can be offset vertically from the ground, positioned above the load-bearing element. The radial forces introduced into the jack during aircraft movement are then absorbed by the load-bearing element at the level of the skid.

[0050] The invention and its advantages will become apparent in more detail in the following description, with illustrative examples given by reference to the attached figures which represent: there figure 1 , an example of an aircraft according to the invention having a wheeled landing gear, the figure 2 , an example of an aircraft according to the invention having a skid landing gear, the figure 3 , a three-dimensional view of a hindrance according to the extended invention, the figure 4 , a three-dimensional view of a hazard having a head interfaced with a landing grid, the figure 5 , a schematic cross-section of a cylinder according to the invention, the figure 6 , a schematic cross-section of a cylinder according to the invention, the figure 7 , a schematic cross-section of a first stop of a cylinder according to the invention, the figure 8 , a schematic cross-section of a second stop of a cylinder according to the invention, the figure 9 , a schematic cross-section of the stops of a cylinder according to the invention arranged in a recess, the figure 10 , a schematic cross-section of the stops of a cylinder according to the invention arranged around a separator, the figure 11 , a diagram illustrating the operation of a hindrance, the figure 12 , a diagram illustrating the positioning of a restraint head in a socket, and the figure 13 , a diagram illustrating the positioning of a head of a restraint between two alveoli.

[0051] Elements present in several separate figures are assigned a single reference.

[0052] THE figures 1 et 2 illustrate examples of aircraft 1 according to this disclosure. Such an aircraft 1 may be an aircraft with or without an onboard pilot.

[0053] As illustrated on the figure 1 , aircraft 1 may include at least one rotary wing 5 carried by a cell 2, the cell 2 being able for example to extend from a nose 3 to a tail 4.

[0054] Furthermore, and regardless of the design, aircraft 1 may include one or more landing gear 6. According to the figure 1 , aircraft 1 may include several landing gear sets, each comprising at least one wheel 7. According to the figure 2 , aircraft 1 may include a skid landing gear 8. Such a skid landing gear includes, for example, at least two skids 8 and at least two cross members 9.

[0055] Regardless of the nature of the aircraft 1 and the type of landing gear it has, an aircraft 1 includes at least one restraint 20 configured to be able to be engaged in a landing grid 10 in a stationary position. A restraint 20 and a landing grid 10 form an assembly 95. Typically, the landing grid 10 includes a structure delimiting cells 11, the structure having separators 12 between adjacent cells 11. The cells 11 may, for example, have cylindrical shapes with a circular base.

[0056] Such a restraint 20 can be supported by a pole 15. This pole 15 can be attached to cell 2 or others, as in the example of the figure 1 , or directly from a landing gear, as in the example of the figure 2 where a restraint 20 is fixed to a skate 8.

[0057] There figure 3 presents a 20-degree obstacle and the figure 4 illustrates this same restraint 20 engaged in a landing grid 10. The restraint 20 is fixed, for illustrative purposes, to a skid 8, but the following explanations are also valid for a fixing to a pole 15, unless otherwise stated.

[0058] With reference to the figure 3 The restraint 20 includes a cylinder 50. The cylinder 50 is equipped with a housing 51 and a head 70 movable in translation relative to the housing 51 along an axis in elevation AXALT relative to the cell or the skid.

[0059] The 70 head has three degrees of rotational freedom ROT1, ROT2, and ROT3 around a longitudinal axis AXL, a transverse axis AXT, and an elevation axis AXALT, respectively. The elevation axis can also be movable relative to the longitudinal axis AXL and the transverse axis AXT.

[0060] In one example, the head 70 is only movable in translation relative to the housing 51, the housing 51 being movable in rotation about the three preceding axes, possibly via a ball joint. In this case, the ball joint allows freedom of movement to the cylinder around the longitudinal axis AXL, the transverse axis AXT, and the vertical axis AXALT.

[0061] According to another example, the head 70 is for this purpose rotationally movable ROT3 relative to the housing 51 around the elevation axis AXALT, this elevation axis being also movable relative to the longitudinal axis AXL and the transverse axis AXT. The actuator 50 can be articulated to a support 30 by means of a joint making it rotationally movable relative to the support 30 only about the longitudinal axis AXL and the transverse axis AXT. The support 30 is then fixed, for example, to a landing gear 6, and for example to a skid 8, or to a boom 15.

[0062] According to the illustrated embodiment, the support 30 may include a frame 31 fixed to the landing gear 6 or to the boom 15. Furthermore, the support 30 includes a joint 32 articulating the housing 51 to the frame 31 along the longitudinal axis AXL and the transverse axis AXT. For example, the joint 32 includes a clevis 33 supported by a bearing or equivalent of the frame 31 to be rotatable about the transverse axis AXT, the actuator 50, and in particular its housing 51, being articulated to the clevis 33 about the longitudinal axis AXL.

[0063] The actuator 50 can be of different types to move the head 70 relative to the aircraft 1 and can be controlled by a control interface 60. Such a control interface 60 can include a button, a touch panel, voice control, an antenna receiving a control signal... The figures 5 et 6 provide non-exhaustive examples of cylinders.

[0064] There figure 5 illustrates an example of a hydraulic or pneumatic cylinder 50, capable of moving the head 70 in translation along the axis in elevation AXALT while leaving it one degree of freedom in rotation around this axis in elevation AXALT.

[0065] According to this example, a piston 52 can separate the internal volume of the housing 51 into two chambers connected to a hydraulic or pneumatic circuit 54 controlled by the control interface 60. The piston 52 is integral with a piston rod 53 carrying the head 70. Furthermore, the head 70 is rotatable about the AXALT axis relative to the housing 51. For example, the piston 52, the piston rod 53, and the head 70 can all be rotatable about the AXALT axis relative to the housing 51.

[0066] There figure 6 This illustrates an example of an electric actuator. The housing 51 contains an electric motor 55, for example, a linear electric motor equipped with an output rod 56 that moves in translation along the elevation axis AXALT. The head 70 can be connected to this output rod 56 with one degree of freedom in rotation about the elevation axis AXALT. For example, the head 70 has a plate arranged between a shoulder 57 of the output rod 56 and a nut 58 or equivalent.

[0067] Regardless of the variant, each cylinder 50 may include standard sensors, means for immobilizing the head 70 and / or may communicate with an alarm capable of signaling the position of the head to an operator.

[0068] Regardless of how the head 70 is made mobile relative to aircraft 1 and with reference again to the figure 3 The restraint 20 includes a force-retaining element 40 to limit the movements of the aircraft 1 relative to the jack 50 and to transmit the forces exerted by the restraint 20 to this aircraft 1. The force-retaining element 40 locally surrounds the jack 50, for example under the joint 32. In addition, the force-retaining element 40 is provided with one or more fixings 42 to be fixed to the support 30, or to the landing gear 6, for example to the skid 8 where applicable, or to the boom 15.

[0069] For this purpose, the load-bearing element 40 may include a retaining ring 41 equipped with one or more fasteners 42. Such a fastener 42 may include an opening through which a screw or rivet passes, for example. The retaining ring 41 surrounds a volume through which the housing 51 passes. The retaining ring has a wall that describes a closed line around the volume, or even around an axis of symmetry of the wall. The housing 51 is movable within this volume. The cylinder 50 therefore has limited freedom of movement relative to the load-bearing element 40.

[0070] To be properly engaged in the landing grid 10, the head 70 includes a free end 72 comprising two stops 75, 76. For example, the head 70 has a base 71 extended along the elevation axis AXALT by the two stops 75, 76. The two stops can extend parallel to each other.

[0071] The two stops 75 and 76 are fixed relative to each other. The two stops 75 and 76 can be positioned on either side of the AXALT elevation axis. Furthermore, a space 90 can separate the two stops perpendicular to the AXALT elevation axis.

[0072] The two stops 75, 76 are dimensioned so that they can jointly enter the same cavity 11 in a locking position, for example by being inscribed in a cylinder with a radius less than the radius of each cavity 11. In addition, the two stops 75, 76 are dimensioned so that they can be fitted around a separator 12 so that one stop 75 is then in a cavity 11 and the other stop 76 is in another adjacent cavity 11 in a locking position.

[0073] To facilitate the positioning of the stops 75,76 in a locking position, each stop 75, 76 may include an end section 77, 78 which tapers away from the housing 51. At least one end section 77,78 may also be rounded.

[0074] In a complementary or alternative manner, the two stops 75, 76 are different.

[0075] According to the figure 7 , a first stop 75 can indeed extend along the AXALT elevation axis over a first length L1, starting from the base 71 if necessary. According to the figure 8 A second stop 76 may extend along the AXALT elevation axis from the base 71, if necessary, over a second length L2 greater than the first length L1. In addition, the second stop 76 may have a rounded end with a radius larger than the radius of the first stop 75.

[0076] According to the figure 9 The two stops 75, 76 can each extend radially, with respect to the AXALT elevation axis, from a rounded internal face 83, 84 to a rounded external face 81, 82. The two internal faces 83, 84 are opposite each other.

[0077] The two external faces 81, 82 can each be concave with respect to the AXALT elevation axis. Conversely, the two internal faces 83, 84 can be convex with respect to the AXALT elevation axis.

[0078] In a plane 99 orthogonal to the elevation axis AXALT, one abutment may have a truncated oval cross-section while the other abutment may have an oval cross-section. According to the illustrated example, the first abutment 75 has a truncated oval cross-section while the second abutment 76 has an oval cross-section.

[0079] According to the figure 9 The two stops 75, 76 can then be inscribed in a socket 11. According to the figure 10 , the two stops 75,76 can be arranged respectively in two adjacent alveoli 11.

[0080] THE figures 11 à 13 illustrate the functioning of obstacle 20.

[0081] With reference to the figure 11 , when the aircraft 1 is landed, the jack 50 is extended, on the possible order of the control interface 60. The head 70 shown schematically moves towards the landing grid 10. The head 70 can then enter directly into a bay 12 if such a bay 11 is located in front of the head 70.

[0082] However, if the head 70 touches the structure of the landing grid 10, the head 70 performs, in conjunction with its translational movement, at least one rotational movement around one of the longitudinal axis AXL, transverse axis AXT, or vertical axis AXALT. The diagram illustrates various possible immobilization positions reached as a result of these movements.

[0083] THE figures 12 et 13 illustrate various situations.

[0084] According to the figure 12 The first stop 75 can contact the structure of the landing grid 10, while the second stop 76 is located in a recess 11 in an intermediate position POSINT. The extension of the cylinder 50 then causes the head 70 to rotate, which drives the first stop 75 into a different recess 11 than the second stop 76 into the final immobilization position POSF.

[0085] According to the figure 13 , the second stop 76 can touch the structure of the landing grid 10, the shorter first stop 75 then being above the landing grid 10. The extension of the cylinder 50 then causes the rotation of the head 70 which leads the first stop 75 and the second stop 76 into the same alveolus 11 in the final immobilization position POSF.

[0086] Naturally, the present invention is subject to numerous variations in its implementation. Although several embodiments have been described, it is understood that it is not conceivable to exhaustively identify all possible embodiments.

Claims

1. Assembly (95) comprising a landing mat (10) provided with several cells (11), each cell (11) being separated from an adjacent cell (11) by a separator (12) of the landing mat (10), the assembly (95) comprising a barrier (20) for an aircraft (1), said barrier (20) comprises a cylinder (50) comprising a housing (51) and a head (70) translatably moveable with respect to the housing (51) along an elevated axis (AXALT), said head (70) having three degrees of freedom in rotation, respectively along a longitudinal axis (AXL) as well as a transverse axis (AXT) and the elevated axis (AXALT), said barrier (20) comprising a force-absorbing member (40) surrounding the cylinder (50) and provided with a fixing (42), capable of being secured to the aircraft (1), characterised in that said head (70) comprises a free end (72) comprising two abutments (75, 76) configured to penetrate together in one same cell (11) of the landing mat (10), said two abutments (75, 76) being immoveable against one another, and separated from one another by a space (90) configured to accommodate a separator (12) of said landing mat (10) separating two said cells (11), said abutments (75, 76) having together a shape being able to fall into each cell (11), said space (90) having a shape being able to contain each separator (12).

2. Assembly according to claim 1, characterised in that said barrier (20) comprises a support (30) carrying said cylinder (50), said cylinder (50) being rotatably moveable with respect to the support (30) along the longitudinal axis (AXL) and the transverse axis (AXT), the head (70) being rotatably moveable with respect to the housing (51) along the elevated axis (AXALT).

3. Assembly according to any one of claims 1 to 2, characterised in that said two abutments (75, 76) each comprise an end section (77, 78) tapered by moving away from said housing (51).

4. Assembly according to claim 3, characterised in that at least one tapered end section (77, 78) is rounded.

5. Assembly according to any one of claims 1 to 4, characterised in that the two abutments (75, 76) are different.

6. Assembly according to claim 5, characterised in that an abutment (75) of said two abutments (75, 76) extends parallel to the elevated axis over a first length (L1) and the other abutment (76) extends parallel to the elevated axis over a second length (L2) greater than the first length (L1).

7. Assembly according to any one of claims 1 to 6, characterised in that said two abutments (75, 76) each comprise a concave, rounded external face (81, 82) facing the elevated axis (AXALT).

8. Assembly according to any one of claims 1 to 7, characterised in that said two abutments (75, 76) each comprise a convex, rounded internal face (83, 84) facing the elevated axis (AXALT).

9. Assembly according to any one of claims 1 to 8, characterised in that an abutment (76) of said two abutments (75, 76) comprises a oval shape in a plane (99) orthogonal to the elevated axis (AXALT) and the other abutment (75) has a truncated oval shape in said plane (99).

10. Assembly according to any one of claims 1 to 9, characterised in that said force-absorbing member (40) comprises a retaining ring (41) surrounding a volume passed through by said housing (51), said housing (51) being moveable in said volume.

11. Assembly according to any one of claims 1 to 10, characterised in that said assembly comprises an aircraft (1) provided with said barrier (20).

12. Assembly according to claim 11, characterised in that said aircraft (1) comprises a landing gear (6), said fixing (42) of said force-absorbing member (40) being secured to the landing gear (6) or to a perch (15) secured to a cell (2) of the aircraft (1).

13. Assembly according to any one of claims 11 to 12, characterised in that, said barrier (20) comprising a support (30) carrying the cylinder (50) and said aircraft (1) comprising a landing gear (6), said support (30) is fixed to the landing gear (6) or to a perch (15) secured to a cell (2) of the aircraft (1).

14. Assembly according to claims 12 and 13, characterised in that said landing gear (6) is a skid landing gear (8), said fixing (42) and the support (30) being fixed to a skid (8) of the landing gear (6), said support (30) having an articulation (32) carrying the cylinder (50), the articulation (32) being located above said force-absorbing member (40) when the aircraft (1) is placed.