Universal linkage planing of main landing gears

Abstract

A main landing gear for an aircraft having universal linkage planing of a wheel assembly is provided. The landing gear can include a main fitting having a trunnion axis; a planing cylinder coupled to the wheel assembly and being received in the main fitting in a coaxial arrangement; a hanger link having a hanger axis; and a planing link having a first end pivotably coupled along a planing axis to an upper portion of the planing cylinder, and a second end rotationally coupled to the hanger link. The planing axis can intersect the trunnion axis, and the trunnion axis and the hanger axis can be fixed with respect to each other. Movement of the main landing gear between a stowed and deployed position causes rotation of the planing cylinder with respect to the main fitting, thereby imparting a planing rotation to the wheel assembly through the planing cylinder.

Description

[0001] UNIVERSAL LINKAGE PLANING OF MAIN LANDING GEARS

[0002] FIELD OF DISCLOSURE

[0003] The present disclosure relates to planing of main landing gear for aircraft using a universal linkage. More particularly, the present disclosure relates to back-driven universal linkage systems to plane the main landing gear during stowage.

[0004] BACKGROUND

[0005] Aircraft are typically equipped with landing gear systems that enables the aircraft to taxi, takeoff, and safely land on the ground. Some aircraft utilize landing gear that is retractable, i.e., the landing gear reciprocates between a deployed (extended) position and a stowed (retracted) position. While the vehicle is on the ground, the landing gear is deployed and supports the vehicle. The landing gear typically incorporates main fittings that permit vertical motion to cushion landing impacts or bump perturbations, dampen repeat oscillations, and minimize the tendency for an aircraft to rebound or “bounce.” In this regard, main fittings commonly include oleo-pneumatic shock-absorbing struts (“oleo struts”) that convert kinetic energy into heat by the use of a gas, providing elastic spring characteristics, and oil, providing dampening. In flight, the landing gear retracts, which reduces drag to lower fuel consumption and permit higher cruise speeds. Examples of a known deploy able and retractable main fittings are described in U.S. Patent No. 10,549,848, issued to Klim et al., and currently assigned to Safran Landing Systems Canada, Inc., the disclosure of which is incorporated herein in its entirety.

[0006] Aircraft technology is trending toward thin supercritical aerofoils, with area-ruling for supersonic and trans-sonic flow. In these increasingly thin configurations, it becomes more difficult to package the main landing gear within the wing structure. Airframers prefer that the engines are moved inboard toward the fuselage to reduce the vertical stabilizer area which is sized for a one-engine-out yaw case. Since the main landing gear height is determined by the height at which tail strike is avoided during take-off rotation, moving the main landing gear inboard will cause the components to touch on the centerline of the aircraft. Conventional configurations include shortening mechanisms or retraction of the main landing gear at an extreme skew angle to avoid touching the keel beam of the aircraft. Current technology landing gear systems are not configured to accommodate thin supercritical aerofoils for supersonic and trans-sonic wing architectures at optimal engine placement.

[0007] SUMMARY

[0008] The present disclosure provides examples of X of an aircraft. In accordance with an aspect of the present disclosure, a landing gear.

[0009] In accordance with another aspect of the present disclosure, a main landing gear for an aircraft having universal linkage planing of a wheel assembly is provided. The main landing gear includes: a main fitting including a trunnion having a trunnion axis and being configured to pivotably couple to the aircraft; a planing cylinder coupled to the wheel assembly in a rotationally fixed configuration, the planing cylinder being received in the main fitting in a coaxial arrangement for relative rotational movement between the planing cylinder and the main fitting; a hanger link having a hanger axis and being configured to pivotably couple to the aircraft; and a planing link having a first end pivotably coupled along a planing axis to an upper portion of the planing cylinder, and a second end rotationally coupled to the hanger link. The planing axis can intersect the trunnion axis, the trunnion axis and the hanger axis can be fixed with respect to each other, and movement of the main landing gear between a stowed position and a deployed position can rotate the main fitting about the trunnion axis and causes a change in the angle of the planing axis with respect to the trunnion axis by rotation of the planing cylinder with respect to the main fitting, thereby imparting a planing rotation to the wheel assembly through the planing cylinder.

[0010] In accordance with another aspect of the present disclosure, a universal linkage for planing of a wheel assembly of a main landing gear for an aircraft is provided. The universal linkage includes: a hanger link configured to pivotably couple to the aircraft at a hanger axis; and a planing link having a pivot protrusion at a first end for rotationally coupling the planing link to the hanger link, and a second end pivotably coupled along a planing axis to an upper portion of a planing cylinder of the main landing gear. The main landing gear can include a main fitting rotatable with respect to the aircraft about a trunnion axis that intersects the planing axis and is fixed with respect to the hanger axis, the planing cylinder can be couplable to the wheel assembly in a rotationally fixed configuration, and the planing cylinder can be receivable within the main fitting in a coaxial arrangement for relative rotational movement between the planing cylinder and the main fitting. In some embodiments, movement of the main landing gear between a stowed position and a deployed position rotates the main fitting about the trunnion axis to back-drive rotation of the planing link with respect to the hanger link through the pivotable coupling at the second end of the planing link, causing a change in the angle of the planing axis with respect to the trunnion axis and rotation of the planing cylinder with respect to the main fitting, thereby imparting a planing rotation to the wheel assembly through the planing cylinder.

[0011] In any of the embodiments of the present disclosure, the planing link comprises a pivot protrusion at the second end for rotationally coupling the planing link to the hanger link.

[0012] In any of the embodiments of the present disclosure, the pivot protrusion has a cylindrical outer surface configured to receive a spherical bearing, and wherein the rotational coupling between the hanger link and the planing link is a spherical rotational coupling.

[0013] In any of the embodiments of the present disclosure, the main landing gear can further include a retraction actuator assembly operably coupled between the main fitting and the aircraft, wherein the retraction actuator assembly is configured to transition the main landing gear between the stowed and deployed positions. In any of the embodiments of the present disclosure, the planing cylinder has a collar configured to interface with the main fitting to prevent axial travel of the planing cylinder with respect to the main fitting.

[0014] In any of the embodiments of the present disclosure, movement of the main landing gear from the stowed position to the deployed position causes the angle of the planing axis with respect to the trunnion axis to decrease.

[0015] In any of the embodiments of the present disclosure, the main landing gear further includes a rolling folding side stay assembly operably coupled between the main fitting and the aircraft, wherein the rolling folding side stay assembly is configured to transition to a locked state to prevent lateral movement of the main landing gear in the deployed position.

[0016] In any of the embodiments of the present disclosure, the planing rotation of the wheel assembly causes the wheel to be tangent to outer mold lines of the aircraft.

[0017] In any of the embodiments of the present disclosure, a planing angle of the planing axis with respect to the trunnion axis as the main landing gear transitions from the deployed position to the stowed position is a range from about 5° to 135°, from about 25° to 100°, from about 40° to 70°, or about 42°.

[0018] 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.

[0019] DESCRIPTION OF THE DRAWINGS

[0020] The foregoing aspects and many of the attendant advantages of the claimed 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: FIGURE 1 depicts one example of an aircraft, such as a passenger or cargo aircraft, shown in top view except showing the landing gear systems, in which technologies and / or methodologies of the present disclosure may be employed;

[0021] FIGURES 2A-2C are perspective views of a main landing gear system of an aircraft in accordance with aspects of the present disclosure, showing a bogie truck assembly coupled to a main fitting, with the main landing gear in a deployed / extended position in FIGURE 2A, an intermediate position in FIGURE 2B, and a stowed / retracted position in FIGURE 2C;

[0022] FIGURES 3A-3C are perspective views of an upper portion of a main landing gear system of an aircraft in accordance with aspects of the present disclosure, showing a main fitting and a universal joint configured to plane the main landing gear during transition between the deployed and stowed positions, with the main landing gear shown in a deployed / extended position in FIGURE 3A, an intermediate position in FIGURE 3B, and a stowed / retracted position in FIGURE 3C; and

[0023] FIGURE 4 is an exploded perspective view of a portion of the main landing gear system of FIGURE 2A.

[0024] DETAILED DESCRIPTION

[0025] The detailed description set forth below 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.

[0026] As will be described in more detail below, the present disclosure provides examples of main landing gear systems having universal linkage planing. Embodiments of the present disclosure include a universal linkage that rotates a planing cylinder inside of a main fitting to turn the wheels during stowage for clearance within the outer mold lines of the aircraft. Embodiments of the planing mechanism are expected to: (1) optimize volume usage in an airframe landing gear bay (e.g., in supercritical airfoils) by turning the wheel during stowage to an angle that avoids aircraft ducts or structure, or to be tangent to the outer mold lines of the aircraft; (2) correct a skewed landing gear axis of rotation so that the wheel(s) become parallel to a certain direction or tangent to the aircraft outer mold lines; (3) avoid using a shortening mechanism; (4) reduce trunnion loads into the main landing gear and into the airframe, where a single skewed trunnion axis permits a wider distance to avoid loads / moments transmitting into the main landing gear; (5) improve airframe fittings, including fitting fusing and breakaway analysis; (6) move the main landing gear attachment points inboard while maintaining the height of the main landing gear to avoid tail strike and permit placement of the engines inboard to reduce the area and / or weight of the vertical tail; and / or (7) transmit bogie torque loads directly into the airframe bypassing the main fitting, which permits a lighter main fitting, among other features and / or advantages.

[0027] Motion in a compound angle (e.g., an angle in two directions) in a landing gear axis of rotation can be utilized to put the wheel(s) back in the desired position, but leads to protrusion from the wing thickness prematurely and can increase the reaction loads on the main landing gear main fitting. Compound angle movement can prevent sufficient clearance from the airframe structure to react the landing gear loads and still fit with in the wing outer mold lines.

[0028] In embodiments described herein, the main landing gear includes a piston / slider (hereinafter “piston”) that slides in a planing cylinder and forms a shock absorber portion of the main landing gear. The piston is attached to the planing cylinder via torsion links to transmit torque from a bogie. The planing cylinder slides inside the main fitting and is allowed to pivot coaxially inside of it. The vertical loads of the shock absorber are absorbed on the bottom of the main fitting at the shoulder interface with the planing cylinder. The planing cylinder is secured to the top of the main fitting via a collar that keeps the planing cylinder from translating out of the main fitting. The top of the plaining cylinder is attached to a set of linkages that function as a back-driven universal linkage (e.g., a universal linkage driven in rotation by motion of the main landing gear), which functions to rotate the planing cylinder during retraction / deployment of the main landing gear. This set of linkages also transmits bogie torque to the airframe of the aircraft, bypassing torque transmission into the main fitting.

[0029] Although embodiments of the present disclosure may be described with reference to universal linkage planing of main landing gear systems for aircraft, one skilled in the relevant art will appreciate that the disclosed embodiments are illustrative in nature and therefore should not be construed as limited to such an application. It should therefore be apparent that the disclosed technologies and methodologies have wide application, and therefore may be suitable for use with many types of suspension and pivot joint architectures for retractable systems. Embodiments of the present disclosure can be used with any number of wheels or arrangements of a main landing gear, and can be viable alternatives to landing gear shortening and / or can reduce torsion loads into the main fitting. For example, embodiments disclosed herein can be used with main landing gear systems having a single-wheel, a twin-wheel, a four-wheel bogie, a six-wheel bogie, a two-wheel tandem, and / or a three-wheel tandem, among others. Accordingly, the following descriptions and illustrations herein should not limit the scope of the claimed subject matter.

[0030] FIGURE 1 depicts one example of an aircraft 100, such as a passenger or cargo aircraft, shown in bottom view, in which technologies and / or methodologies of the present disclosure may be employed. The aircraft 100 can include a nose landing gear system 110, and a universal linkage planing system (see FIGURES 2A-4) integrated at least partially into a right main landing gear system 120a and a left main landing gear system 120b. Although embodiments of the present disclosure are described herein with reference to the main landing gear systems 120a and 120b having a bogie with six wheels, the universal linkage planing systems are also suitable for use with other main landing gear configurations, as noted above. As used herein, left and right directions are in reference to the perspective of the pilot seated in the cockpit facing the standard forward direction of travel. The landing gear systems 110, 120a, and 120b can include various components configured to support the body of the aircraft 100 above the ground surface, e.g., wheels, tires, shock absorbers, brackets, hydraulics, sensors, controllers, etc., and such components are not shown for the sake of clarity in the FIGURES. It should be appreciated that the aircraft 100 illustrated in FIGURE 1 should not be considered limiting on the present disclosure, and the landing gear systems can be arranged in various other configurations with fewer or additional components as desired. In addition, the particular location of the landing gear systems, the quantity of wheels and tires, and the other aspects of the aircraft 100 illustrated in FIGURE 1 should not be considered limiting on the present disclosure, as the components may be positioned at various locations. In the FIGURES, certain well- known components, such as washers, bushings, fasteners, sleeves, and the like may not be described in detail to improve clarity in the detailed description; however, each of these components are configured for use with the components of the present disclosure in any suitable capacity, such as that shown in the FIGURES.

[0031] FIGURES 2A-2C are perspective views of a main landing gear system 200 (such as the main landing gear systems 120a and 120b shown in FIGURE 1), of an aircraft in accordance with aspects of the present disclosure. FIGURES 2A-2C show a bogie truck assembly 202 (in broken line) coupled to a main fitting 214, with the main landing gear system 200 in a deploy ed / extended position in FIGURE 2A, an intermediate position in FIGURE 2B, and a stowed / retracted position in FIGURE 2C. In the present disclosure, the deploy ed / extended position shown in FIGURE 2A is intended to represent the position at which the main landing gear 200 would be used when the aircraft is landing, taxiing, or taking off, and the stowed / retracted position shown in FIGURE 2C is intended to represent the position at which the main landing gear 200 would be used when the aircraft is in flight. The intermediate position shown in FIGURE 2B is intended to be a representative position as the main landing gear system 200 transitions between the deployed and stowed positions.

[0032] The bogie truck assembly 202 can include various components configured to carry sets of aircraft wheels of the main landing gear system 200. Although the illustrated bogie truck assembly 202 of FIGURES 2A-2C is configured to carry three sets of wheels (six total wheels), embodiments of the present disclosure are suitable for use with any number of wheels sets in a landing gear system, for example, two sets of wheels (see FIGURE 1), greater than three sets of wheels, or a single set of wheels, among others. During maneuvers of the aircraft, such as landing and takeoff when both sets of wheels do not contact the runway simultaneously, the bogie truck assembly 202 is permitted to articulate about a bogie pivot joint and accommodate the relative skew of the runway with respect to the aircraft 100.

[0033] The main fitting assembly 210 includes a drag stay 212 having a trunnion 218 (having a forward pintle pin), a main fitting 214, and a planing cylinder 222 that is rotationally movable (coaxial rotation) within the main fitting 214. The movement of the planing cylinder 222 with respect to the main fitting 214 permits shock absorption by the main fitting assembly 210, such as during landing of the aircraft. The planing cylinder 222 is attached to a piston (not shown) via torsion links to transmit torque from the bogie truck assembly 202. The planing cylinder 222 is permitted to slide inside the main fitting 214 and pivot coaxially inside of it during use of the main landing gear 200. The vertical loads of the shock absorbing portion of the main fitting assembly 210 are absorbed on the bottom of the main fitting 214 at the shoulder interface with the planing cylinder 222. Further, the planing cylinder 222 is secured to the top of the main fitting 214 via a collar 216 that keeps the planing cylinder 222 from translating down and out of the main fitting 214.

[0034] The main landing gear system 200 further includes a rolling folding side stay assembly 230 to lock the landing gear in the deployed position, the rolling folding side stay assembly 230 having a top pivot 232 operably coupled to the aircraft, a lower pivot 224 having a pivot pin 226 operably coupled to the main fitting 214, an actuator 238, and a locking stay 236 having a pivot 234. The rolling folding side stay assembly 230 is configured to provide lateral locking to the main landing gear system 200 such that the lateral forces into the bogie truck assembly 202 are not transmitted solely by a retraction actuator assembly 240. The retraction actuator assembly 240 is operably coupled to the upper portion of the main fitting assembly 210 and is operably to extend and retract to translate the main landing gear system 200 between the stowed and deployed positions. For example, from the fully extended position of the retraction actuator assembly 240 shown in FIGURE 2A (main landing gear deployed), the retraction actuator assembly 240 retracts to move the main landing gear system 200 to the intermediate position shown in FIGURE 2B, and then retracts further to move the main landing gear system 200 to the stowed position shown in FIGURE 2C. From the position shown in FIGURE 2C, the retraction actuator assembly 240 extends to deploy the main landing gear system 200.

[0035] The top of the plaining cylinder 222 is attached to a set of linkages that function as a back-driven universal linkage (e.g., a universal linkage driven in rotation by motion of the main landing gear), which functions to rotate the planing cylinder during retraction / deployment of the main landing gear. This set of linkages also transmits bogie torque to the airframe of the aircraft, bypassing torque transmission into the main fitting. The back-driven universal linkage has a hanger link 220 operably coupled to the aircraft by a pivot aperture 223. The hanger link 220 and the components of the back-driven universal linkage will be described in greater detail below with respect to FIGURES 3A- 3C.

[0036] FIGURES 3A-3C are perspective views of an upper portion of the main landing gear system 200 in accordance with aspects of the present disclosure. The main fitting assembly 210 includes a universal joint assembly 308 that is configured to plane the main landing gear system 200 during transition between the deployed and stowed positions. Similarly to FIGURES 2A-2C, the main landing gear is shown in a deployed / extended position in FIGURE 3A, an intermediate position in FIGURE 3B, and a sto wed / retracted position in FIGURE 3C. The universal joint assembly 308 includes a planing link 310 operably coupled between the hanger link 220 and the planing cylinder 222. In some embodiments, the planing link 310 is operably coupled to an upper portion of the planing cylinder 222 at a universal link pinned joint 312 that permits angular rotation between the components. The universal link pinned joint 312 can include corresponding rotationenabling components that will be described in view of FIGURE 4, below. At the opposite end, the planing link 310 includes a pivot protrusion 314 and a pivot nut 315 configured to operably couple the planing link 310 to the hanger link 220. The coupling between the pivot protrusion 314 and the hanger link 220 can include the pivot nut 315 interfacing with a spherical bushing 221 that permits movement between the components without twisting the wheels of the bogie truck assembly 202. The spherical bushing 221 can be any conventional spherical bushing, e.g., metal on metal, maintenance-free, polymer such as Polytetrafluoroethylene, and the like, that is configured to provide rotational movement at a central point of the spherical bushing 221.

[0037] The rotation of the universal j oint assembly 308 permits planing of the wheels of the main landing gear system 200 during stowage to orient the wheels in a way to correct a skewed landing gear axis of rotation so that the wheel(s) become parallel to a certain direction or tangent to the aircraft outer mold lines. The rotation of the universal joint assembly 308 can be observed in comparison between FIGURES 3A, 3B, and 3C. Starting with FIGURE 3A, when the main landing gear system is in the deployed position, the retraction actuator assembly 240 is in a fully extended position with the rolling folding side stay assembly 230 in a locked state. The upper main fitting assembly 210 has the trunnion 218 creating a pivot point for the main fitting assembly 210 with respect to the aircraft. The forward pintle pin 422 (see FIGURE 4) in the trunnion rotates about a trunnion axis A, the universal link pinned joint 312 rotates about a universal joint axis B that is perpendicular to a central axis of the planing cylinder 222 (e.g., the axis along which the piston travels), and the hanger link 220 rotates at the pivot aperture 223 about a hanger axis C. The planing link 310 can have a longitudinal axis F extending through a center of the pivot protrusion 314 and intersecting the axis B in a perpendicular manner. In some embodiments, a plane formed through the axes B and F is parallel to the axis C through the movement range of the main landing gear system 200. Further axes are shown in FIGURE 3 A, including the top pivot 232 that rotates about a pivot axis D, and a pivot point of the retraction actuator assembly 240 that rotates about a pivot axis E. The pivot axes D and E are shown in exemplary positions for informational purposes only and can be located in different suitable orientations and / or positions relative to other components based on the geometry of the aircraft.

[0038] Referring now to FIGURES 3A and 3B together, as the main landing gear system 200 transitions away from the deployed position in FIGURE 3A toward the stowed position, the retraction actuator assembly 240 retracts, the rolling folding side stay assembly 230 unlocks, and the main fitting assembly 210 begins to rotate about the trunnion axis A toward the stowed position in FIGURE 3C. As shown in FIGURE 3B, the trunnion axis A and the hanger axis C are generally mounted to the aircraft in a fixed position with respect to each other; however, the universal joint axis B changes position with respect to the axes A and C. In this regard, as can be seen in the transition from FIGURE 3A to FIGURE 3B, the universal joint axis B intersects the trunnion axis A and rotates to a different angular position with respect to the trunnion axis A, with an angle disposed between the axes A and B increasing as the main landing gear system 200 translates from the deployed position to the stowed position. The increase in the angle between the axes A and B imparts a rotation into the planing cylinder 222 with respect to the main fitting 214. As viewed from the top of the planing cylinder 222 from the orientation shown in FIGURE 3B, the rotation of the planing cylinder 222 is clockwise with respect to the main fitting 214. During the transition, and axis of the pivot protrusion 314 may change direction with respect to the hanger link 220 through the spherical bearing 221. In this regard, the hanger link 220 may rotate about the hanger axis C during transition of the main landing gear system 200 between the stowed and deployed positions.

[0039] Referring now to FIGURES 3B and 3C together, as the main landing gear system 200 transitions further toward the stowed position and FIGURE 3C, the retraction actuator assembly 240 further retracts, the rolling folding side stay assembly 230 continues to fold, and the main fitting assembly 210 further rotate about the trunnion axis A. In the transition from FIGURE 3B to FIGURE 3C, the angle disposed between the axes A and B continues to increase and imparts the clockwise rotation into the planing cylinder 222 with respect to the main fitting 214. The rotation of the planing cylinder 222 during stowage results in a planing of the wheels of the bogie assembly 202, permitting positioning of the wheels with clearance to the outer mold lines of the aircraft. The configuration of the universal joint assembly 308 can transmit torque loads from the bogie assembly 202 directly into the airframe through the planing link 310, the pivot protrusion 314, and the hanger link 220. The torque load path can bypass the main fitting 214, which permits designs having a lighter weight main fitting.

[0040] In some embodiments, the overall difference in the angle between the axes A and B as the main landing gear system 200 transitions from the deployed position (FIGURE 3A) to the stowed position (FIGURE 3C) is the planing angle. The planing angle is the degree of angular rotational of the bogie truck assembly 202 (e.g., the wheels) with respect to the main fitting 214. The planing angle can have a range from about 5° to 135°, from about 25° to 100°, from about 40° to 70°, or can be about 42°. For example, the angle between the axes A and B in the deployed position can range from about 15° to about 30°, or greater, and in the stowed position can range from about 70°, or less, to about 150°. In the illustrated embodiment, the angle between the axes A and B in the deployed position (FIGURE 3 A) is about 29°, and in the stowed position (FIGURE 3C) is about 71°, which results in a planing angle of about 42° during the range of motion between the deployed to stowed positions.

[0041] FIGURE 4 is an exploded perspective view of a portion of the main landing gear system 200 of FIGURE 2A, generally showing the pivot assembly components of the main fitting assembly 310. Components of the spherical bearing 221 are shown for reference. The planing cylinder 222 includes an upper pivot mount protrusion 410 containing one or more bushing components 412. The upper pivot mount protrusion receives the universal link pinned joint 312 therethrough. The planing cylinder 222 includes a lower pivot joint 416 to which the links of the bogie assembly 202 are operably coupled. The main fitting 214 has the trunnion 218 including the forward pintle pin 422. The forward pintle pin 422 can have bushings 420 to permit rotation of the trunnion 218 at the axis A. The retraction actuator assembly 240 can have a pivot mount 430 on the drag stay 212.

[0042] 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 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.

[0043] 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 terms “about,” “approximately,” “near,” etc. , mean plus or minus 10% of the stated value. F or 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.

[0044] It should be noted that for purposes of this disclosure, terminology such as “upper,” “lower,” “vertical,” “horizontal,” “fore,” “aft,” “inner,” “outer,” “front,” “rear,” etc., should be construed as descriptive and not limiting the scope of the claimed subject matter. Further, the use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings.

[0045] 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.

[0046] 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 main landing gear for an aircraft having universal linkage planing of a wheel assembly, the main landing gear comprising: a main fitting including a trunnion having a trunnion axis and being configured to pivotably couple to the aircraft; a planing cylinder coupled to the wheel assembly in a rotationally fixed configuration, the planing cylinder being received in the main fitting in a coaxial arrangement for relative rotational movement between the planing cylinder and the main fitting; a hanger link having a hanger axis and being configured to pivotably couple to the aircraft; and a planing link having a first end pivotably coupled along a planing axis to an upper portion of the planing cylinder, and a second end rotationally coupled to the hanger link, wherein the planing axis intersects the trunnion axis, wherein the trunnion axis and the hanger axis are fixed with respect to each other, and wherein movement of the main landing gear between a stowed position and a deployed position rotates the main fitting about the trunnion axis and causes a change in the angle of the planing axis with respect to the trunnion axis by rotation of the planing cylinder with respect to the main fitting, thereby imparting a planing rotation to the wheel assembly through the planing cylinder.

2. The main landing gear of Claim 1, wherein the planing link comprises a pivot protrusion at the second end for rotationally coupling the planing link to the hanger link.

3. The main landing gear of Claim 2, wherein the pivot protrusion has a cylindrical outer surface configured to receive a spherical bearing, and wherein the rotational coupling between the hanger link and the planing link is a spherical rotational coupling.

4. The main landing gear of Claim 1, further comprising a retraction actuator assembly operably coupled between the main fitting and the aircraft, wherein the retraction actuator assembly is configured to transition the main landing gear between the stowed and deployed positions.

5. The main landing gear of Claim 1, wherein the planing cylinder has a collar configured to interface with the main fitting to prevent axial travel of the planing cylinder with respect to the main fitting.

6. The main landing gear of Claim 1, wherein movement of the main landing gear from the stowed position to the deployed position causes the angle of the planing axis with respect to the trunnion axis to decrease.

7. The main landing gear of Claim 1, further comprising a rolling folding side stay assembly operably coupled between the main fitting and the aircraft, wherein the rolling folding side stay assembly is configured to transition to a locked state to prevent lateral movement of the main landing gear in the deployed position.

8. The main landing gear of Claim 1 , wherein the planing rotation of the wheel assembly causes the wheel to be tangent to outer mold lines of the aircraft.

9. The main landing gear of Claim 1, wherein a planing angle of the planing axis with respect to the trunnion axis as the main landing gear transitions from the deployed position to the stowed position is a range from about 5° to 135°.

10. The main landing gear of Claim 1, wherein a planing angle of the planing axis with respect to the trunnion axis as the main landing gear transitions from the deployed position to the stowed position is a range from about 25° to 100°.

11. The main landing gear of Claim 1, wherein a planing angle of the planing axis with respect to the trunnion axis as the main landing gear transitions from the deployed position to the stowed position is a range from about 40° to 70°.

12. The main landing gear of Claim 1, wherein a planing angle of the planing axis with respect to the trunnion axis as the main landing gear transitions from the deployed position to the stowed position is about 42°.

13. A universal linkage for planing of a wheel assembly of a main landing gear for an aircraft, the universal linkage comprising: a hanger link configured to pivotably couple to the aircraft at a hanger axis; and a planing link having a pivot protrusion at a first end for rotationally coupling the planing link to the hanger link, and a second end pivotably coupled along a planing axis to an upper portion of a planing cylinder of the main landing gear, wherein the main landing gear includes a main fitting rotatable with respect to the aircraft about a trunnion axis that intersects the planing axis and is fixed with respect to the hanger axis, wherein the planing cylinder is couplable to the wheel assembly in a rotationally fixed configuration, wherein the planing cylinder is receivable within the main fitting in a coaxial arrangement for relative rotational movement between the planing cylinder and the main fitting, and wherein movement of the main landing gear between a stowed position and a deployed position rotates the main fitting about the trunnion axis to back-drive rotation of the planing link with respect to the hanger link through the pivotable coupling at the second end of the planing link, causing a change in the angle of the planing axis with respect tothe trunnion axis and rotation of the planing cylinder with respect to the main fitting, thereby imparting a planing rotation to the wheel assembly through the planing cylinder.

14. The universal linkage of Claim 13, wherein the pivot protrusion has a cylindrical outer surface configured to receive a spherical bearing, and wherein the rotational coupling between the hanger link and the planing link is a spherical rotational coupling.

15. The universal linkage of Claim 14, wherein the planing cylinder has a collar configured to interface with the main fitting to prevent axial travel of the planing cylinder with respect to the main fitting.

16. The universal linkage of Claims 13, wherein movement of the main landing gear from the stowed position to the deployed position causes the angle of the planing axis with respect to the trunnion axis to decrease.

17. The universal linkage of Claim 13 , wherein the planing rotation of the wheel assembly causes the wheel to be tangent to outer mold lines of the aircraft.

18. The universal linkage of Claim 13, wherein a planing angle of the planing axis with respect to the trunnion axis as the main landing gear transitions from the deployed position to the stowed position is a range from about 5° to 135°.

19. The universal linkage of Claim 13, wherein a planing angle of the planing axis with respect to the trunnion axis as the main landing gear transitions from the deployed position to the stowed position is a range from about 40° to 70°.

20. The universal linkage of Claim 15, wherein a planing angle of the planing axis with respect to the trunnion axis as the main landing gear transitions from the deployed position to the stowed position is about 42°.

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