Articulated landing gear door with drive linkage

Abstract

A landing gear for an aircraft having an airframe includes a strut rotatably mounted to the airframe about a first axis for selective rotation between a stowed position and a deployed position. A first door is fixedly associated with the strut, and a second door is hingedly coupled to the first door about a second axis. An elongate drive link has a first end rotatably coupled to the second door about a third axis. A second end of the drive link is rotatably coupled about a fourth axis to the airframe. Rotation of the strut about the first axis drives rotation of the second door relative to the first door about the second axis.

Description

[0001] ARTICULATED LANDING GEAR DOOR WITH DRIVE LINKAGE

[0002] BACKGROUND

[0003] [1] Modem aircraft landing gear is typically retractable, i.e., reciprocal between a deployed position and a stowed position. In the deployed position, the landing gear extends downward from the aircraft to engage a ground surface and support the aircraft during takeoff, landing, and taxiing maneuvers. To improve aerodynamic efficiency, the landing gear is retracted to the stowed position when the aircraft is in flight. With respect to main landing gear assemblies in particular, the landing gear is typically stowed within a landing gear bay located in the wing and / or the fuselage of the aircraft.

[0004] [2] When the landing gear is in the stowed position, one or more landing gear doors are in a closed position to provide an aerodynamic cover for the landing gear bay opening. When the landing gear moves from the stowed position to the deployed position, the landing gear doors move to an open position to allow the landing gear to move out of the landing gear bay.

[0005] [3] Smaller landing gear may have simple, one-piece outboard doors that are hinged at the airframe and driven by a linkage coupled to the leg of the main landing gear. This works well for simple cantilever main landing gear and with some semiarticulated landing gear. However, for landing gear that requires a longer outboard door, the sweep of the opening door can become excessive. To address this issue, the outboard door can be split into two or more portions. For such configuration, a system to articulate the separate portions of the door is required. In some configurations, a fixed portion of the outboard door is mounted to the leg of the main landing gear, and a lower portion of the outboard door is hingedly coupled to the fixed portion. A mechanism driven from a non-planar side brace can be utilized to drive the lower portion relative to the fixed portion. However, the requirements of such mechanism can result in complex and heavy mechanisms.

[0006] SUMMARY

[0007] [4] Embodiments of landing gear and with articulated landing gear doors are set forth below according to technologies and methodologies of the present disclosure. The landing gear doors can be driven by in-plane actuators / side braces and / or “out-of-plane” actuators / side braces. Further, the drive mechanism that articulates the landing gear doors provides redundancy in the case of component failure.

[0008] [5] A representative embodiment of a landing gear for an aircraft having an airframe includes a strut rotatably mounted to the airframe about a first axis for selective rotation between a stowed position and a deployed position. A first door is fixedly associated with the strut, and a second door is hingedly coupled to the first door about a second axis. An elongate drive link has a first end rotatably coupled to the second door about a third axis. A second end of the drive link is rotatably coupled about a fourth axis to the airframe. Rotation of the strut about the first axis drives rotation of the second door relative to the first door about the second axis.

[0009] [6] In any embodiment, the airframe, the strut, the second door, and the drive link define a four-bar linkage.

[0010] [7] In any embodiment, the four-bar linkage is a crossing four-bar linkage.

[0011] [8] In any embodiment, the second door includes a panel and a gooseneck fitting that extends from an edge of the panel, wherein the first end of the drive link is rotatably coupled to the gooseneck fitting.

[0012] [9] In any embodiment, selective rotation of the strut reciprocates the landing gear between a stowed position and a deployed position.

[0013]

[0010] In any embodiment, the landing gear further comprises an actuator associated with the strut, wherein the strut selectively drives reciprocating motion of the landing gear between the stowed position and the deployed position.

[0014]

[0011] In any embodiment, the actuator is a linear actuator, a first end of the actuator being rotatably mounted to the airframe about a fifth axis, a second end of the actuator being rotatably coupled to the strut.

[0015]

[0012] In any embodiment, the first axis, second axis, third axis, and fourth axis are parallel to each other.

[0016]

[0013] In any embodiment, the fifth axis is not parallel to the first axis.

[0017]

[0014] In any embodiment, retraction of the linear actuator drives the landing gear toward the stowed position, and extension of the linear actuator drives the landing gear toward the deployed position.

[0018]

[0015] In any embodiment, the linear actuator is a locking actuator.

[0016] In any embodiment, the landing gear further comprises a second drive link having a first end rotatably coupled to the second door and a second end rotatably coupled to the airframe.

[0019]

[0017] In any embodiment, the rotational coupling of the first end of the second drive link is coaxial with the rotational coupling of the first end of the first drive link.

[0020]

[0018] In any embodiment, the rotational coupling of the second end of the second drive link is coaxial with the rotational coupling of the second end of the first drive link.

[0021]

[0019] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0022] DESCRIPTION OF THE DRAWINGS

[0023]

[0020] The foregoing aspects and many of the attendant advantages of the disclosed subject matter will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

[0024]

[0021] FIGURE 1 shows a forward-looking view of a left-hand side main landing gear of an aircraft with an articulated flap door according to aspects of the present disclosure, wherein the landing gear is in an extended position and the aircraft is on the ground;

[0025]

[0022] FIGURE 2 shows an outboard-looking view of the landing gear of FIGURE 1;

[0026]

[0023] FIGURE 3 shows a forward-looking view of the landing gear of FIGURE 1, wherein the main landing gear is in the extended position, and the aircraft is in flight;

[0027]

[0024] FIGURE 4 shows a forward-looking view of the landing gear of FIGURE 3, wherein the main landing gear is between the extended position and a retracted position;

[0028]

[0025] FIGURE 5 shows a forward-looking view of the landing gear of FIGURE 3, wherein the main landing gear is in the retracted position;

[0026] FIGURE 6 shows a detailed partial view of the landing gear as indicated in FIGURE 3;

[0029]

[0027] FIGURE 7 shows a detailed partial view of the landing gear as indicated in FIGURE 4;

[0030]

[0028] FIGURE 8 s shows a detailed partial view of the landing gear as indicated in FIGURE 5; and

[0031]

[0029] FIGURE 9 shows a schematic view of a four-bar linkage defined by the landing gear of FIGURE 6.

[0032] DETAILED DESCRIPTION

[0033]

[0030] FIGURES 1 and 2 show an embodiment of a landing gear 50 of an aircraft 30 according to aspects of the present disclosure. The landing gear 50 includes a shock strut 60 that may have a hybrid pneumatic and hydraulic function, sometimes referred to as an oleo strut (or oleo pneumatic strut). The shock strut includes a cylinder 62 and a piston 66 that is slidably received within the cylinder. A first end of the cylinder 62 includes a trunnion 64 rotatably mounted to the airframe 32 about an axis 200. As used herein, the airframe 32 is a fixed structure positioned within the wheel well of the aircraft 50; however, it will be appreciated that components of the landing gear 50 and, in particular, the cylinder 62 may be coupled to any suitable structure within the wheel well or otherwise located on the aircraft 30.

[0034]

[0031] The piston 66 extends from a second end of the cylinder 62. A bogie 68 is rotatably coupled to the cylinder 62 about an axis 202 and is configured to have one or more wheels 70 rotatably mounted thereto. In the illustrated embodiment, two pairs of wheels 70 are mounted to the bogie 68, wherein each pair of wheels is rotatably mounted about an axis 204. The present disclosure is not limited to a particular wheel and / or bogie configuration. In this regard, various embodiments may include different wheel configurations, including those having different numbers of wheels and / or wheels that are mounted to the piston in any suitable manner.

[0035]

[0032] Typically, the shock strut 60 is filled with a compressible gas and an incompressible fluid. For example, the gas may be nitrogen which is relatively inert, and the fluid may be a hydraulic fluid. When the aircraft 30 is on the ground 20, as shown in FIGURES 1 and 2, the wheels 70 support the weight of the aircraft, which compresses the shock strut 60, i.e., drives the piston 66 upward into the cylinder 62. The gas acts as a spring, elastically absorbing some of the energy of the landing. The piston 66 forces hydraulic fluid through flow restrictions in the cylinder 62, thereby dissipating energy as work and heat, and reducing the tendency of the aircraft to rebound or bounce during landings.

[0036]

[0033] A torque link assembly 72 has a first end rotatably coupled to the cylinder 62 and a second end rotatably coupled to the bogie 68. The torque link assembly 72 restrains the bogie 68 and, therefore, the wheels 70 in rotation relative to the cylinder 62 about a central axis of the shock strut 70. A bogie positioner 74 is rotatably coupled at one end to the cylinder 62 and at another end to the bogie 68. The bogie positioner 74 orients the bogie 68 relative to the cylinder 62 about axis 202 so that the bogie is properly positioned when the landing gear 50 moves into the stowed position.

[0037]

[0034] A side brace actuator 76 selectively drives rotation of the shock strut 60 about axis 200 to move the landing gear 50 between the stowed position and the deployed position. In the illustrated embodiment, side brace actuator 76 is a locking linear actuator. A first end of the side brace actuator 76 is rotatably mounted to the airframe 32 about an axis 206. A second end of the side brace actuator 76 is rotatably coupled to the cylinder 62 about an axis 208. As the side brace actuator 76 extends, the landing gear 50 is driven toward the deployed position, and as the side brace actuator retracts, the landing gear is driven toward the stowed position. In some embodiments, extension and retraction of the side brace actuator 76 is in a plane normal to axis 200 of rotation of the shock strut 60, i.e., the actuation is “in plane.” In some embodiments, extension and retraction of the side brace actuator 76 is in a plane normal to axis 200 of rotation of the shock strut 60, i.e., the actuation is “out of plane.”

[0038]

[0035] As previously noted, the side brace actuator 76 of the illustrated embodiment is a locking linear actuator. Locking the actuator when the landing gear 50 is in the stowed or deployed position maintains the landing gear in position. In some embodiments known downlocks, uplocks, side stays and other devices may be utilized in addition to or in lieu of the locking feature of the linear actuator in order to maintain the landing gear 50 in the deployed and / or stowed positions. In some embodiments, various different types of actuators or combinations of actuators, including linear actuators, rotary actuators, hydraulic actuators, electric actuators, pneumatic actuators, or any other suitable type of actuators or combination of actuators may be utilized.

[0039]

[0036] The landing gear 50 includes an articulated door assembly 100 that includes a first door (“fixed door 110”) fixedly positioned relative to the cylinder 62 of the shock strut 60 and a second door (“flap door 120”) rotatably coupled to the fixed door. When the landing gear 50 is in the stowed position, the fixed door 110 and the flap door 120 cooperate to at least partially covers wheel well opening. As will be described in greater detail, movement of the landing gear 50 from the stowed position to the deployed position rotates the fixed door 110, while also driving rotation of the flap door 120 relative to the fixed door 110. As shown in FIGURES 1 and 2, when the landing gear is in the deployed position, the flap door 120 is rotated away from the wheels 70 so that sufficient clearance is provided between the flap door and the wheels, even when the shock strut 60 is compressed.

[0040]

[0037] Referring now to FIGURES 3-5, movement of the landing gear 50 from the deployed position (FIGURE 3), through an intermediate position (FIGURE 4), to the stowed position (FIGURE 5) is shown. Because the landing gear 50 is retracting, the aircraft 30 is airborne, and the shock strut 60 is extended under the weight of the bogie 68 and the wheels 70.

[0041]

[0038] As best shown in FIGURE 5, when the landing gear 50 stowed position, the flap door 120 is adjacent to an inboard door 80, and the fixed door 110 is adjacent to an outboard door 82. For the sake of clarity, the inboard door 80 and the outboard door 82 are each represented by a curve indicating the outer mold line (OML) at an aft edge. With the landing gear in the stowed position, the outer surfaces of the inboard door 80, flap door 120, fixed door 110, and outboard door 82 cooperate to form a generally smooth, aerodynamic surface that at least partially covers the landing gear bay and the landing gear 50 positioned therein.

[0042]

[0039] The inboard door 80 maintains a raised position when the landing gear 50 is in the stowed position of FIGURE 5 and the deployed position of FIGURE 3. When the landing gear 50 moves from the stowed position to the deployed position or from the deployed position to the stowed position, the inboard door 80 temporarily rotates to a lowered position to provide clearance that enables the landing gear 50 to move through intermediate position of FIGURE 4.

[0043]

[0040] The outboard door 82 maintains a raised position when the landing gear 50 is in the stowed position of FIGURE 5. As the landing gear 50 moves to the deployed position of FIGURE 3, the outboard door 82 rotates to a lowered position. The outboard door 82 maintains the lowered position until the landing gear 50 returns to the stowed position, at which point the outboard door returns to the raised position. Throughout the reciprocating motion of the landing gear 50 between the stowed and deployed positions, the outboard door 82 remains generally parallel with the fixed door 110.

[0044]

[0041] The illustrated inboard door 80 and outboard door 82 are exemplary only and should not be considered limiting. In some embodiments, the number, shape, location, and kinematic properties of the doors surrounding the fixed door 110 and flap door 120 can vary in any suitable manner. These and other embodiments are contemplated and should be considered within the scope of the present disclosure.

[0045]

[0042] Referring now to FIGURES 6-8, the actuation of the fixed door 110 and the flap door 120 will now be described. The fixed door 110 includes a panel 112 having an outer surface 114. In some embodiments, the panel 112 is a composite panel. In some embodiments, the composite panel includes a honeycomb portion. In some embodiments, the panel 112 has any construction that provides suitable strength, durability, and weight characteristics.

[0046]

[0043] As previously noted, the fixed door 110 is fixedly positioned relative to the cylinder 62 of the shock strut 60. The fixed door 110 maintains its position relative to the cylinder 62 as the landing gear 50 reciprocates between the stowed position and the deployed position. As a result, like the shock strut 60, the fixed door 110 rotates about axis 200 as the landing gear 50 reciprocates between the stowed position and the deployed position.

[0047]

[0044] The flap door 120 includes a panel 122 having an outer surface 124. In some embodiments, the panel is a composite panel. In some embodiments, the composite panel includes a honeycomb portion. In some embodiments, the panel has any construction that provides suitable strength, durability, and weight characteristics.

[0048]

[0045] The flap door 120 is rotatably coupled to the fixed door 110 about an axis 210. In the illustrated embodiment, a hinge 128 rotatable attaches a lower end of the fixed door 110 to an inboard end of the flap door 120 (as viewed in FIGURE 6). In some embodiments, the flap door 120 is rotatably coupled to the fixed door 110 by any suitable configuration instead of or in addition to one or more hinges. In some embodiments, the flap door 120 is rotatably coupled to the fixed door 110 by lug / clevis combinations, hinges, gooseneck fittings, or any other suitable mechanism or combination of mechanisms.

[0049]

[0046] The flap door 120 further includes one or more gooseneck fittings 126 extending from the edge of the flap door that is coupled to the fixed door. As shown in FIGURE 2, the disclosed flap door 120 includes a pair of gooseneck fittings 126 spaced apart along the edge of the flap door 120. In some embodiments, the flap door 120 can have a single gooseneck fitting 126 or any suitable number of gooseneck fittings spaced along the edge of the flap door. In some embodiments, the gooseneck fittings 126 are identical. In some embodiments, the gooseneck fittings 126 have different configurations.

[0050]

[0047] Referring back to FIGURE 6, each gooseneck fitting 126 is rotatably coupled to an end of an elongate drive link 130 about an axis 214. In the illustrated embodiment, the gooseneck fitting 126 includes a clevis and the drive link 130 includes a spherical bearing positioned between the legs of the clevis. In some embodiments, the gooseneck fitting 126 and the drive link 130 are rotatably coupled by any suitable joint that allows rotation about axis 214 without causing binding.

[0051]

[0048] A second end of the drive link 130 is rotatably coupled about an axis 212 that is fixedly positioned relative to the axis 200 about which the shock strut 60 rotates. In some embodiments, the second end of the drive link 130 is rotatably coupled to a portion of the airframe 32 within the wheel well. In the illustrated embodiment, the airframe 32 includes a clevis and the drive link 130 includes a spherical bearing positioned between the legs of the clevis. In some embodiments, the drive link 130 is rotatably coupled to the airframe 32 by any suitable joint that allows rotation about axis 214 without causing binding.

[0052]

[0049] Referring now to FIGURE 9, operation of the landing gear 50 will be described. As indicated by the overlaid lines, the shock strut 60, fixed door 110, flap door 120, and drive link 130 cooperate to define a crossing four-bar linkage ABCD. Axes 200 and 210 are fixedly positioned relative to each other and define leg AB; axes 210 and 214 are fixedly positioned relative to each other and define leg BC; axes 214 and 212 are fixedly positioned relative to each other to define leg CD; and axes 212 and 200 are fixedly positioned relative to each other to define leg AD. Leg AD is fixedly positioned relative to the airframe 32 and acts as the ground link of the linkage. Leg AB acts as the input link and is driven in rotation as the side brace actuator rotates the shock strut 60 about axis 200. The four-bar linkage is a “crossing” four-bar linkage because leg AB crosses leg CD.

[0053]

[0050] During extension or retraction of the landing gear, the side brace actuator 76 rotates the shock strut 60 about axis 200. The fixed door 110, which is fixedly positioned relative to the shock strut 60, rotates about axis 200 with the shock strut. As the shock strut rotates about axis 200, the linkage rotates the flap door 120 about axis 210 relative to the fixed door 110.

[0054]

[0051] In the illustrated embodiments, axes 200, 210, 212, and 214 are parallel to each other. The inclusion of parallel axes enables the use of multiple drive links 130, which in turn provides redundancy to the drive system. Such redundancy can be important for supersonic flight and / or for compliance with Extended Twin-Engine Operations (ETOPS) requirements. In some embodiments, one or more of the axes 200, 210, 212, and 214 are not parallel with the others. In some embodiments, even when all of the axes not parallel, multiple drive links may be included by utilizing spherical rod ends at the axis connections. In some embodiments, a single drive link may be utilized.

[0055]

[0052] Embodiments of the illustrated landing gear provide a simplified, lightweight articulated door assembly suitable to be driven by out-of-plane actuators. Further the use of more than one drive link provides redundancy in the linkage.

[0056]

[0053] While illustrative embodiments have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.

[0057]

[0054] The detailed description set forth above in connection with the appended drawings, where like numerals reference like elements, are intended as a description of various embodiments of the present disclosure and are not intended to represent the only embodiments. Each embodiment described in this disclosure is provided merely as an example or illustration and should not be construed as preferred or advantageous over other embodiments. The illustrative examples provided herein are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Similarly, any steps described herein may be interchangeable with other steps, or combinations of steps, in order to achieve the same or substantially similar result. Moreover, some of the method steps can be carried serially or in parallel, or in any order unless specifically expressed or understood in the context of other method steps.

[0058]

[0055] In the foregoing description, specific details are set forth to provide a thorough understanding of exemplary embodiments of the present disclosure. It will be apparent to one skilled in the art, however, that the embodiments disclosed herein may be practiced without embodying all of the specific details. In some instances, well-known method / process steps have not been described in detail in order not to unnecessarily obscure various aspects of the present disclosure. Further, it will be appreciated that embodiments of the present disclosure may employ any combination of features described herein.

[0059]

[0056] The present application may reference quantities and numbers. Unless specifically stated, such quantities and numbers are not to be considered restrictive, but exemplary of the possible quantities or numbers associated with the present application. Also, in this regard, the present application may use the term “plurality” to reference a quantity or number. In this regard, the term “plurality” is meant to be any number that is more than one, for example, two, three, four, five, etc. The term “about,” “approximately,” etc., means plus or minus 5% of the stated value. For the purposes of the present disclosure, the phrase “at least one of A and B” is equivalent to “A and / or B” or vice versa, namely “A” alone, “B” alone or “A and B.” Similarly, the phrase “at least one of A, B, and C,” for example, means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C), including all further possible permutations when greater than three elements are listed.

[0060]

[0057] Throughout this specification, terms of art may be used. These terms are to take on their ordinary meaning in the art from which they come, unless specifically defined herein or the context of their use would clearly suggest otherwise.

[0061]

[0058] The principles, representative embodiments, and modes of operation of the present disclosure have been described in the foregoing description. However, aspects of the present disclosure, which are intended to be protected, are not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. It will be appreciated that variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present disclosure. Accordingly, it is expressly intended that all such variations, changes, and equivalents fall within the spirit and scope of the present disclosure as claimed.

Claims

CLAIMSThe embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A landing gear for an aircraft having an airframe, the landing gear comprising: a strut rotatably mounted to the airframe about a first axis for selective rotation between a stowed position and a deployed position; a first door fixedly associated with the strut; a second door hingedly coupled to the first door about a second axis; and an elongate drive link having a first end rotatably coupled to the second door about a third axis, a second end of the drive link being rotatably coupled about a fourth axis to the airframe, wherein rotation of the strut about the first axis drives rotation of the second door relative to the first door about the second axis.

2. The landing gear of Claim 1, wherein the airframe, the strut, the second door, and the drive link define a four-bar linkage.

3. The landing gear of Claim 2, wherein the four-bar linkage is a crossing four-bar linkage.

4. The landing gear of Claim 3, wherein the second door includes a panel and a gooseneck fitting that extends from an edge of the panel, wherein the first end of the drive link is rotatably coupled to the gooseneck fitting.

5. The landing gear of Claim 1, wherein selective rotation of the strut reciprocates the landing gear between a stowed position and a deployed position.

6. The landing gear of Claim 5, further comprising an actuator associated with the strut, wherein the strut selectively drives reciprocating motion of the landing gear between the stowed position and the deployed position.

7. The landing gear of Claim 6, wherein the actuator is a linear actuator, a first end of the actuator being rotatably mounted to the airframe about a fifth axis, a second end of the actuator being rotatably coupled to the strut.

8. The landing gear of Claim 7, wherein the first axis, second axis, third axis, and fourth axis are parallel to each other.

9. The landing gear of Claim 8, wherein the fifth axis is not parallel to the first axis.

10. The landing gear of Claim 7, wherein in retraction of the linear actuator drives the landing gear toward the stowed position, and extension of the linear actuator drives the landing gear toward the deployed position.

11. The landing gear of Claim 10, wherein the linear actuator is a locking actuator.

12. The landing gear of Claim 1, further comprising a second drive link having a first end rotatably coupled to the second door and a second end rotatably coupled to the airframe.

13. The landing gear of Claim 12, wherein the rotational coupling of the first end of the second drive link is coaxial with the rotational coupling of the first end of the first drive link.

14. The landing gear of Claim 13, wherein the rotational coupling of the second end of the second drive link is coaxial with the rotational coupling of the second end of the first drive link.

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