US20210316845A9 - Composite twin beam main landing gear for an aircraft - Google Patents
Composite twin beam main landing gear for an aircraft Download PDFInfo
- Publication number
- US20210316845A9 US20210316845A9 US16/426,357 US201916426357A US2021316845A9 US 20210316845 A9 US20210316845 A9 US 20210316845A9 US 201916426357 A US201916426357 A US 201916426357A US 2021316845 A9 US2021316845 A9 US 2021316845A9
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- United States
- Prior art keywords
- trunnion
- leaf
- main leaf
- gear assembly
- landing gear
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F1/00—Springs
- F16F1/36—Springs made of rubber or other material having high internal friction, e.g. thermoplastic elastomers
- F16F1/366—Springs made of rubber or other material having high internal friction, e.g. thermoplastic elastomers made of fibre-reinforced plastics, i.e. characterised by their special construction from such materials
- F16F1/368—Leaf springs
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C25/00—Alighting gear
- B64C25/32—Alighting gear characterised by elements which contact the ground or similar surface
- B64C25/58—Arrangements or adaptations of shock-absorbers or springs
- B64C25/62—Spring shock-absorbers; Springs
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F1/00—Springs
- F16F1/02—Springs made of steel or other material having low internal friction; Wound, torsion, leaf, cup, ring or the like springs, the material of the spring not being relevant
- F16F1/18—Leaf springs
- F16F1/20—Leaf springs with layers, e.g. anti-friction layers, or with rollers between the leaves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F1/00—Springs
- F16F1/02—Springs made of steel or other material having low internal friction; Wound, torsion, leaf, cup, ring or the like springs, the material of the spring not being relevant
- F16F1/18—Leaf springs
- F16F1/26—Attachments or mountings
- F16F1/28—Attachments or mountings comprising cylindrical metal pins pivoted in close-fitting sleeves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F1/00—Springs
- F16F1/02—Springs made of steel or other material having low internal friction; Wound, torsion, leaf, cup, ring or the like springs, the material of the spring not being relevant
- F16F1/18—Leaf springs
- F16F1/26—Attachments or mountings
- F16F1/30—Attachments or mountings comprising intermediate pieces made of rubber or similar elastic material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C25/00—Alighting gear
- B64C25/32—Alighting gear characterised by elements which contact the ground or similar surface
- B64C25/34—Alighting gear characterised by elements which contact the ground or similar surface wheeled type, e.g. multi-wheeled bogies
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F1/00—Springs
- F16F1/36—Springs made of rubber or other material having high internal friction, e.g. thermoplastic elastomers
- F16F1/366—Springs made of rubber or other material having high internal friction, e.g. thermoplastic elastomers made of fibre-reinforced plastics, i.e. characterised by their special construction from such materials
- F16F1/368—Leaf springs
- F16F1/3683—Attachments or mountings therefor
- F16F1/3686—End mountings
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F2224/00—Materials; Material properties
- F16F2224/02—Materials; Material properties solids
- F16F2224/0241—Fibre-reinforced plastics [FRP]
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F2224/00—Materials; Material properties
- F16F2224/02—Materials; Material properties solids
- F16F2224/025—Elastomers
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F2226/00—Manufacturing; Treatments
- F16F2226/04—Assembly or fixing methods; methods to form or fashion parts
Definitions
- the present invention pertains generally to aircraft landing gears. More particularly, the present invention pertains to aircraft landing gears that are made using a composite material. The present invention is particularly, but not exclusively, useful for the manufacture of aircraft landing gears which have two (i.e. upper and lower), coplanar beams.
- the forces acting against the landing gear of an aircraft during landing can be substantial.
- the rebound vibrations experienced by a landing gear during either a bounce after landing, or following takeoff can also have detrimental effects for the aircraft.
- a main landing gear and/or a nose gear for an aircraft wherein the structure between the aircraft's fuselage and the main gear wheels and the nose wheel are made of a light-weight composite materials.
- Another object of the present invention is to provide a main landing gear and/or a nose gear for an aircraft which is made of a composite material with a structure that will both resist landing forces and suppress unwanted resultant vibrations.
- Still another object of the present invention is to provide an aircraft main landing gear and/or a nose gear that is (are) made of a composite material, that is easy to manufacture, is simple to use and is comparatively cost effective.
- a landing gear assembly for an aircraft includes a trunnion assembly that is mounted on the fuselage of the aircraft, and an axel support structure which supports a wheel(s) on the landing gear assembly.
- a flexure unit which is made of a composite material, is engaged between the trunnion assembly and the axel support structure. Structurally, the flexure unit includes an upper beam having a length L (upper) , and a lower beam having a length L (lower) .
- each beam has a proximal end that is mounted on the trunnion assembly. Also, each beam has a distal end that is affixed to the axel support structure. In combination with each other, the upper beam and the lower beam are coplanar to jointly establish a flexure unit. It is envisioned that the flexure unit will be vertically oriented to resist planar flexures of the gear assembly.
- each beam includes a respective main leaf. It may, however, also include at least one stub leaf.
- the main leaf extends through the length L (upper)
- the main leaf extends through the length L (lower) .
- a stub leaf extends above and along the main leaf of the upper beam from the trunnion assembly through a distance that is less than L (upper) .
- a stub leaf extends above and along the main leaf of the lower beam from the trunnion assembly through a distance that is less than L (lower) .
- Each stub leaf is positioned above its respective main leaf to create a gap between them.
- Additional stub leaves can be similarly added above a lower stub leaf with gaps therebetween in either the upper beam or the lower beam, as desired.
- an energy absorbing elastomer is made part of the structure in the gap between the stub leaf and the main leaf, and in the gaps between adjacent stub leaves, if incorporated.
- the proximal end of the upper beam, and the proximal end of the lower beam can be connected to the trunnion assembly with a distance s p between them.
- the distal end of the upper beam and the distal end of the lower beam can be connected to the axel support structure with a distance s d between them.
- s p will be equal to or greater than s d .
- trusses can be incorporated into the flexure unit between the upper and lower beams.
- respective trusses can be interconnected between the beams and with the axel support structure or the trunnion assembly.
- the overall purpose of the flexure unit is to dissipate energy and to dampen rebound vibrations during a flexure of the gear assembly.
- An additional structural feature of the landing gear assembly is an upper back-up laminate that is connected to the axel support structure and positioned in contact with the upper beam.
- the upper back-up laminate extends in a proximal direction from the axel support structure, and it is positioned below and in contact with the upper main leaf to support the upper main leaf during a flexure of the flexure unit.
- a lower back-up laminate is also connected to the axel support structure. Like the upper back-up laminate, it extends in a proximal direction from the axel support structure. Further, it is positioned below and in contact with the lower main leaf, to support the lower main leaf during a flexure of the gear assembly.
- the axel support structure is made of a composite material that is integrated with composite structures of the upper beam and the lower beam. These components are then co-cured to create a monolithic unitary structure for the landing gear.
- the axel support structure includes an outboard plate, an upper inboard plate, and a lower inboard plate that are bonded with the upper beam and the lower beam.
- the term “outbound” means farthest from the fuselage, and the term “inbound” means closest to the aircraft fuselage.
- the upper main leaf and the upper back-up laminate of the flexure unit are co-cured or bonded, together with the axel support structure, between the outboard plate and the upper inboard plate.
- the lower main leaf and the lower back-up laminate are co-cured or bonded together between the outboard plate and the lower inboard plate.
- the axel support structure, the upper beam and the lower beam can all be made of a same composite material prior to being respectively co-cured or bonded with the upper beam and the lower beam.
- the trunnion assembly includes a trunnion body which has a threaded upper end and a threaded lower end.
- a threaded upper trunnion nut is engaged with the threaded upper end of the trunnion body to hold the upper beam and any upper stub leaves there may be, between the upper trunnion nut and the trunnion body.
- a threaded lower trunnion nut is engaged with the threaded lower end of the trunnion body to hold the lower beam and any lower stub leaves, together with a drag link, between the lower trunnion nut and the trunnion body.
- FIG. 1 is a perspective view of a composite twin beam main landing gear assembly for an aircraft in accordance with the present invention
- FIG. 2A is a perspective view of a cure tool which is useful for manufacturing a flexure unit as a unitary structure
- FIG. 2B is a perspective view of a cure tool which is useful for manufacturing the leaves, and specified portions thereof, for a beam in the flexure unit of the landing gear assembly;
- FIG. 3 is a side elevation view of the composite twin beam main landing gear assembly
- FIG. 4 is a perspective view of an axel support structure used in the landing gear assembly for supporting an aircraft wheel, and for establishing an engagement with the distal ends of the upper and lower beams in the flexure unit of the present invention
- FIG. 5 is a cross section view of the axel support structure as seen along the line 5 - 5 in FIG. 4 :
- FIG. 6 is a perspective view of a trunnion assembly for establishing an engagement with the proximal ends of upper and lower beams in the flexure unit of the present invention.
- FIG. 7 is a cross section view of the trunnion assembly as seen along the line 7 - 7 in FIG. 6 .
- a composite twin beam main landing gear assembly for an aircraft in accordance with the present invention is shown, and is generally designated 10 .
- the gear assembly 10 includes a flexure unit 12 , which is made of a composite material and which extends between a trunnion assembly 14 and an axel support structure 16 .
- the flexure unit 12 includes an upper beam 18 having a length L (upper) , and a lower beam 20 having a length L (lower) .
- the upper beam 18 and the lower beam 20 are coplanar and, in use, will generally be in a vertical plane.
- the trunnion assembly 14 will be attached to the fuselage or to a wing of an aircraft (not shown), and the axel support structure 16 will support at least one landing wheel (not shown), which is mounted on axel 21 .
- the essential components of the flexure unit 12 are made of a composite material which incorporates carbon fibers and a compound of epoxy or other resins.
- these components are manufactured using cure tools, such as the mandrel type cure tool 22 a shown in FIG. 2A and the cure tool 22 b shown in FIG. 2B .
- cure tool 22 a and cure tool 22 b are formed with an undulating and cuspidate surface.
- the cure tool 22 b is shown with a centerline 24 that defines the surface.
- a mandrel type cure tool 22 a which can be used to manufacture a flexure unit 12 in accordance with the present invention as a unitary structure.
- the cure tool 22 a is designed with undulating and cuspidate surfaces that conform with the desired structural components for an upper beam 18 , and for a lower beam 20 of the flexure unit 12 .
- the composite material for the desired unitary flexure unit 12 can be applied onto the cure tool 22 a , prior to being cured.
- the present invention also envisions the use of a substrate type cure tool 22 b as shown in FIG. 2B .
- a strip of composite material having a predetermined width and a predetermined thickness can be laid along its centerline 24 and subsequently cured in accordance with techniques well known in the pertinent art.
- the result here is the creation of a laminate element 25 .
- FIG. 2B shows a cure tool 22 b being used for the manufacture of a laminate element 25 that will eventually become an upper main leaf 26 (see FIG. 3 ). It is to be understood, however, that the same cure tool 22 b can be used to manufacture other laminate elements 25 having shorter lengths measured along selected portions of the centerline 24 .
- a similar cure tool 22 b ′ (not shown), which is symmetrical to the cure tool 22 b , can be used for the manufacture of a flexure unit 12 b ′ (not shown) which will be used on the side of an aircraft opposite the side on which the flexure unit 12 is to be used.
- the structure for the upper beam 18 is shown to include the upper main leaf 26 . Additionally, the upper beam 18 includes an upper stub leaf 28 a and an upper stub leaf 28 b which are positioned sequentially above the main leaf 26 . In this combination, the upper stub leaves 28 a and 28 b extend parallel along the upper main leaf 26 in a distal direction from the trunnion assembly 14 . As also shown in FIG. 3 , a gap 30 a is created between the main leaf 26 and the stub leaf 28 a . Also, a gap 30 b is created between the stub leaf 28 a and the stub leaf 28 b.
- the lower beam 20 of flexure unit 12 includes a lower main leaf 32 . Further, a lower stub leaf 34 a and a lower stub leaf 34 b are positioned sequentially above the lower main leaf 32 . In this combination, the lower stub leaves 34 a and 34 b extend parallel along the lower main leaf 32 in a distal direction from the trunnion assembly 14 . As also shown in FIG. 3 , a gap 36 a is created between the main leaf 32 and the stub leaf 34 a . Additionally, a gap 36 b is created between the stub leaf 34 a and the stub leaf 34 b.
- interleaves 38 which are made of a gum rubber, are used to fill the respective gaps 30 a and 30 b of the upper main leaf 26 , and the gaps 36 a and 36 b of the lower main leaf 32 .
- gum rubber for the interleaves 38 will be an energy-absorbing elastomer, such as Airdam 1, Sorbothane, or AN-VI rubber.
- the flexure unit 12 includes an upper back-up laminate 40 that is mounted on the axel support structure 16 .
- the upper back-up laminate 40 extends in a proximal direction from the axel support structure 16 , below the upper main leaf 26 . Further, it is shown that the back-up laminate 40 is in contact with the upper main leaf 26 to support the upper main leaf 26 during a flexure of the gear assembly 10 .
- a lower back-up laminate 42 is mounted on the axel support structure 16 to extend in a proximal direction therefrom below the lower main leaf 32 . As shown, the lower back-up laminate 42 is in contact with the lower main leaf 32 to support the lower main leaf 32 during a flexure of the gear assembly 10 .
- the connection between a flexure unit 12 and the axel support structure 16 will be best appreciated with reference to FIG. 5 .
- the axel support structure 16 includes an outboard plate 44 , an upper inboard plate 46 , and a lower inboard plate 48 .
- the upper main leaf 26 and the upper back-up laminate 40 are co-cured, bonded or held together between the outboard plate 44 and the upper inboard plate 46 .
- the lower main leaf 32 and the lower back-up laminate 42 are co-cured, bonded or held together between the outboard plate 44 and the lower inboard plate 48 .
- the upper back-up laminate 40 and the lower back-up laminate 42 can be incorporated into the composite material used to manufacture the axel support structure 16 .
- the trunnion assembly 14 is connected with the respective proximal ends of the upper beam 18 and the lower beam 20 .
- the interconnection of these components will be best appreciated with reference to FIG. 7 .
- the trunnion assembly 14 includes a trunnion pin 50 which is surrounded by a trunnion body 52 having a threaded upper end 54 and a threaded lower end 56 .
- a threaded upper trunnion nut 58 is shown engaged with the threaded upper end of the trunnion body 52 .
- a threaded lower trunnion nut 60 is engaged with the threaded lower end of the trunnion body 52 .
- the laminate elements 25 that are included in the upper beam 18 are positioned between the upper trunnion nut 58 and the upper end 54 of the trunnion body 52 .
- the upper trunnion nut 58 is then threaded onto the trunnion body 52 to hold the upper main leaf 26 and the upper stub leaves 28 a and 28 b between the upper trunnion nut 58 and the trunnion body 52 .
- the lower trunnion nut 60 is threaded onto the lower end 56 of the trunnion body 52 to hold the lower main leaf 32 , the lower stub leaves 34 a and 34 b and a drag link 62 between the lower trunnion nut 60 and the trunnion body 52 .
- the outboard plate 44 , the upper inboard plate 46 , the lower inboard plate 48 , the trunnion pin 50 , the trunnion body 52 , the upper trunnion nut 58 and the lower trunnion nut 60 are all made of a material selected from the group consisting of stainless steel, aluminum and titanium.
- the proximal end of the upper composite leaf spring (i.e. upper beam 18 ), and the proximal end of the lower composite leaf spring (i.e. lower beam 20 ), are mounted on the trunnion assembly 14 with a distance s p between them.
- the distal end of the upper composite leaf spring (i.e. upper beam 18 ) and the distal end of the lower composite leaf spring (i.e. lower beam 20 ) are mounted on a axel support structure 16 with a distance s d between them.
- s p and s d are equal to, or substantially equal to, each other.
- a coplanar relationship is established between the upper beam 18 and the lower beam 20 .
- the present invention also envisions its use for the manufacture of a nose gear assembly. In the case of a nose gear assembly, however, it is most likely that, rather than creating a flexure unit 12 , only one beam (e.g. a composite leaf spring) would be used. Further, although the above disclosure has also focused on retractable gear assemblies, it is to be appreciated that with minimal modifications the present invention can be just as well used for the manufacture of fixed gear assemblies.
Abstract
Description
- The present invention pertains generally to aircraft landing gears. More particularly, the present invention pertains to aircraft landing gears that are made using a composite material. The present invention is particularly, but not exclusively, useful for the manufacture of aircraft landing gears which have two (i.e. upper and lower), coplanar beams.
- The forces acting against the landing gear of an aircraft during landing can be substantial. Moreover, the rebound vibrations experienced by a landing gear during either a bounce after landing, or following takeoff, can also have detrimental effects for the aircraft. Thus, it has always been important to ensure that the landing gear of an aircraft is strong, yet flexible enough to absorb impact energy loads in order to absorb the landing forces on the aircraft. Also it is important that the landing gear be properly damped to suppress vibrations and recoil.
- As the aviation industry continues to move further toward the use of light-weight materials for the manufacture of aircraft, composite materials have become increasingly interesting. Heretofore, however, the use of composite materials for landing gears have been given scant consideration. As a consequence, the total weight of a landing gear assembly, including necessary shock absorbers, can be undesirably heavy.
- In light of the above, it is an object of the present invention to provide a main landing gear and/or a nose gear for an aircraft wherein the structure between the aircraft's fuselage and the main gear wheels and the nose wheel are made of a light-weight composite materials. Another object of the present invention is to provide a main landing gear and/or a nose gear for an aircraft which is made of a composite material with a structure that will both resist landing forces and suppress unwanted resultant vibrations. Still another object of the present invention is to provide an aircraft main landing gear and/or a nose gear that is (are) made of a composite material, that is easy to manufacture, is simple to use and is comparatively cost effective.
- In accordance with the present invention a landing gear assembly for an aircraft includes a trunnion assembly that is mounted on the fuselage of the aircraft, and an axel support structure which supports a wheel(s) on the landing gear assembly. A flexure unit, which is made of a composite material, is engaged between the trunnion assembly and the axel support structure. Structurally, the flexure unit includes an upper beam having a length L(upper), and a lower beam having a length L(lower).
- In the flexure unit, each beam has a proximal end that is mounted on the trunnion assembly. Also, each beam has a distal end that is affixed to the axel support structure. In combination with each other, the upper beam and the lower beam are coplanar to jointly establish a flexure unit. It is envisioned that the flexure unit will be vertically oriented to resist planar flexures of the gear assembly.
- In detail, each beam includes a respective main leaf. It may, however, also include at least one stub leaf. In the upper beam the main leaf extends through the length L(upper), and in the lower beam, the main leaf extends through the length L(lower). Further, if incorporated, a stub leaf extends above and along the main leaf of the upper beam from the trunnion assembly through a distance that is less than L(upper). Similarly, if incorporated, a stub leaf extends above and along the main leaf of the lower beam from the trunnion assembly through a distance that is less than L(lower). Each stub leaf is positioned above its respective main leaf to create a gap between them. Additional stub leaves can be similarly added above a lower stub leaf with gaps therebetween in either the upper beam or the lower beam, as desired. In each case, an energy absorbing elastomer is made part of the structure in the gap between the stub leaf and the main leaf, and in the gaps between adjacent stub leaves, if incorporated.
- For a flexure unit of the present invention, the proximal end of the upper beam, and the proximal end of the lower beam can be connected to the trunnion assembly with a distance sp between them. Also, the distal end of the upper beam and the distal end of the lower beam can be connected to the axel support structure with a distance sd between them. Typically, sp will be equal to or greater than sd. Additionally, trusses can be incorporated into the flexure unit between the upper and lower beams. In detail, respective trusses can be interconnected between the beams and with the axel support structure or the trunnion assembly. Within the structure disclosed here, the overall purpose of the flexure unit is to dissipate energy and to dampen rebound vibrations during a flexure of the gear assembly.
- An additional structural feature of the landing gear assembly is an upper back-up laminate that is connected to the axel support structure and positioned in contact with the upper beam. Specifically, the upper back-up laminate extends in a proximal direction from the axel support structure, and it is positioned below and in contact with the upper main leaf to support the upper main leaf during a flexure of the flexure unit. Similarly, a lower back-up laminate is also connected to the axel support structure. Like the upper back-up laminate, it extends in a proximal direction from the axel support structure. Further, it is positioned below and in contact with the lower main leaf, to support the lower main leaf during a flexure of the gear assembly.
- For a manufacture of the landing gear assembly of the present invention in accordance with a first embodiment, the axel support structure is made of a composite material that is integrated with composite structures of the upper beam and the lower beam. These components are then co-cured to create a monolithic unitary structure for the landing gear.
- For a second embodiment of the present invention, the axel support structure includes an outboard plate, an upper inboard plate, and a lower inboard plate that are bonded with the upper beam and the lower beam. Note: for purposes of this disclosure, the term “outbound” means farthest from the fuselage, and the term “inbound” means closest to the aircraft fuselage. In detail, the upper main leaf and the upper back-up laminate of the flexure unit are co-cured or bonded, together with the axel support structure, between the outboard plate and the upper inboard plate. Further, the lower main leaf and the lower back-up laminate are co-cured or bonded together between the outboard plate and the lower inboard plate. For this second embodiment, the axel support structure, the upper beam and the lower beam can all be made of a same composite material prior to being respectively co-cured or bonded with the upper beam and the lower beam.
- Also, for the manufacture of the landing gear assembly, the trunnion assembly includes a trunnion body which has a threaded upper end and a threaded lower end. A threaded upper trunnion nut is engaged with the threaded upper end of the trunnion body to hold the upper beam and any upper stub leaves there may be, between the upper trunnion nut and the trunnion body. Similarly, a threaded lower trunnion nut is engaged with the threaded lower end of the trunnion body to hold the lower beam and any lower stub leaves, together with a drag link, between the lower trunnion nut and the trunnion body.
- The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference character's refer to similar parts, and in which:
-
FIG. 1 is a perspective view of a composite twin beam main landing gear assembly for an aircraft in accordance with the present invention; -
FIG. 2A is a perspective view of a cure tool which is useful for manufacturing a flexure unit as a unitary structure; -
FIG. 2B is a perspective view of a cure tool which is useful for manufacturing the leaves, and specified portions thereof, for a beam in the flexure unit of the landing gear assembly; -
FIG. 3 is a side elevation view of the composite twin beam main landing gear assembly; -
FIG. 4 is a perspective view of an axel support structure used in the landing gear assembly for supporting an aircraft wheel, and for establishing an engagement with the distal ends of the upper and lower beams in the flexure unit of the present invention; -
FIG. 5 is a cross section view of the axel support structure as seen along the line 5-5 inFIG. 4 : -
FIG. 6 is a perspective view of a trunnion assembly for establishing an engagement with the proximal ends of upper and lower beams in the flexure unit of the present invention; and -
FIG. 7 is a cross section view of the trunnion assembly as seen along the line 7-7 inFIG. 6 . - Referring initially to
FIG. 1 a composite twin beam main landing gear assembly for an aircraft in accordance with the present invention is shown, and is generally designated 10. As shown thegear assembly 10 includes aflexure unit 12, which is made of a composite material and which extends between atrunnion assembly 14 and anaxel support structure 16. Further, it is seen that theflexure unit 12 includes anupper beam 18 having a length L(upper), and alower beam 20 having a length L(lower). In combination, theupper beam 18 and thelower beam 20 are coplanar and, in use, will generally be in a vertical plane. As intended for the present invention, thetrunnion assembly 14 will be attached to the fuselage or to a wing of an aircraft (not shown), and theaxel support structure 16 will support at least one landing wheel (not shown), which is mounted onaxel 21. - An important aspect of the present invention is the fact that the essential components of the
flexure unit 12 are made of a composite material which incorporates carbon fibers and a compound of epoxy or other resins. In detail, these components are manufactured using cure tools, such as the mandreltype cure tool 22 a shown inFIG. 2A and thecure tool 22 b shown inFIG. 2B . As shown, bothcure tool 22 a andcure tool 22 b are formed with an undulating and cuspidate surface. InFIG. 2B thecure tool 22 b is shown with acenterline 24 that defines the surface. - In
FIG. 2A , a mandreltype cure tool 22 a is shown which can be used to manufacture aflexure unit 12 in accordance with the present invention as a unitary structure. In detail, thecure tool 22 a is designed with undulating and cuspidate surfaces that conform with the desired structural components for anupper beam 18, and for alower beam 20 of theflexure unit 12. Thus, with a rotation of thecure tool 22 a around theaxis 23 of thecure tool 22 a, the composite material for the desiredunitary flexure unit 12 can be applied onto thecure tool 22 a, prior to being cured. - The present invention also envisions the use of a substrate
type cure tool 22 b as shown inFIG. 2B . When using thecure tool 22 b, a strip of composite material having a predetermined width and a predetermined thickness can be laid along itscenterline 24 and subsequently cured in accordance with techniques well known in the pertinent art. The result here is the creation of alaminate element 25. In particular,FIG. 2B shows acure tool 22 b being used for the manufacture of alaminate element 25 that will eventually become an upper main leaf 26 (seeFIG. 3 ). It is to be understood, however, that thesame cure tool 22 b can be used to manufacture otherlaminate elements 25 having shorter lengths measured along selected portions of thecenterline 24. Moreover, asimilar cure tool 22 b′ (not shown), which is symmetrical to thecure tool 22 b, can be used for the manufacture of a flexure unit 12 b′ (not shown) which will be used on the side of an aircraft opposite the side on which theflexure unit 12 is to be used. - Referring now to
FIG. 3 , the structure for theupper beam 18 is shown to include the uppermain leaf 26. Additionally, theupper beam 18 includes anupper stub leaf 28 a and anupper stub leaf 28 b which are positioned sequentially above themain leaf 26. In this combination, the upper stub leaves 28 a and 28 b extend parallel along the uppermain leaf 26 in a distal direction from thetrunnion assembly 14. As also shown inFIG. 3 , agap 30 a is created between themain leaf 26 and thestub leaf 28 a. Also, agap 30 b is created between thestub leaf 28 a and thestub leaf 28 b. - Structurally similar to the
upper beam 18, thelower beam 20 offlexure unit 12 includes a lowermain leaf 32. Further, alower stub leaf 34 a and alower stub leaf 34 b are positioned sequentially above the lowermain leaf 32. In this combination, the lower stub leaves 34 a and 34 b extend parallel along the lowermain leaf 32 in a distal direction from thetrunnion assembly 14. As also shown inFIG. 3 , agap 36 a is created between themain leaf 32 and thestub leaf 34 a. Additionally, agap 36 b is created between thestub leaf 34 a and thestub leaf 34 b. - As intended for the present invention, interleaves 38, which are made of a gum rubber, are used to fill the
respective gaps main leaf 26, and thegaps main leaf 32. Preferably, gum rubber for theinterleaves 38 will be an energy-absorbing elastomer, such as Airdam 1, Sorbothane, or AN-VI rubber. - With reference to
FIG. 4 it will be seen that theflexure unit 12 includes an upper back-uplaminate 40 that is mounted on theaxel support structure 16. As shown, the upper back-uplaminate 40 extends in a proximal direction from theaxel support structure 16, below the uppermain leaf 26. Further, it is shown that the back-uplaminate 40 is in contact with the uppermain leaf 26 to support the uppermain leaf 26 during a flexure of thegear assembly 10. Also, a lower back-uplaminate 42 is mounted on theaxel support structure 16 to extend in a proximal direction therefrom below the lowermain leaf 32. As shown, the lower back-uplaminate 42 is in contact with the lowermain leaf 32 to support the lowermain leaf 32 during a flexure of thegear assembly 10. - The connection between a
flexure unit 12 and theaxel support structure 16 will be best appreciated with reference toFIG. 5 . There it is to be appreciated that a complete cured assembly for theaxel support structure 16 is shown. As shown, theaxel support structure 16 includes anoutboard plate 44, an upperinboard plate 46, and alower inboard plate 48. As shown, the uppermain leaf 26 and the upper back-uplaminate 40 are co-cured, bonded or held together between theoutboard plate 44 and the upperinboard plate 46. On the other hand, the lowermain leaf 32 and the lower back-uplaminate 42 are co-cured, bonded or held together between theoutboard plate 44 and thelower inboard plate 48. For an alternate embodiment of theaxel support structure 16, wherein theflexure unit 12 is manufactured as a unitary structure, the upper back-uplaminate 40 and the lower back-uplaminate 42 can be incorporated into the composite material used to manufacture theaxel support structure 16. - In
FIG. 6 it will be seen that thetrunnion assembly 14 is connected with the respective proximal ends of theupper beam 18 and thelower beam 20. The interconnection of these components will be best appreciated with reference toFIG. 7 . For this purpose, it will be seen that thetrunnion assembly 14 includes atrunnion pin 50 which is surrounded by atrunnion body 52 having a threadedupper end 54 and a threadedlower end 56. InFIG. 7 , a threadedupper trunnion nut 58 is shown engaged with the threaded upper end of thetrunnion body 52. And, it is also seen that a threadedlower trunnion nut 60 is engaged with the threaded lower end of thetrunnion body 52. - In order to engage the
upper beam 18 with thetrunnion assembly 14, thelaminate elements 25 that are included in the upper beam 18 (i.e. the uppermain leaf 26, and the stub leaves 28 a and 28 b) are positioned between theupper trunnion nut 58 and theupper end 54 of thetrunnion body 52. Theupper trunnion nut 58 is then threaded onto thetrunnion body 52 to hold the uppermain leaf 26 and the upper stub leaves 28 a and 28 b between theupper trunnion nut 58 and thetrunnion body 52. Likewise, thelower trunnion nut 60 is threaded onto thelower end 56 of thetrunnion body 52 to hold the lowermain leaf 32, the lower stub leaves 34 a and 34 b and adrag link 62 between thelower trunnion nut 60 and thetrunnion body 52. Preferably, when used, theoutboard plate 44, the upperinboard plate 46, thelower inboard plate 48, thetrunnion pin 50, thetrunnion body 52, theupper trunnion nut 58 and thelower trunnion nut 60 are all made of a material selected from the group consisting of stainless steel, aluminum and titanium. - For an assembly of the main landing gear, the proximal end of the upper composite leaf spring (i.e. upper beam 18), and the proximal end of the lower composite leaf spring (i.e. lower beam 20), are mounted on the
trunnion assembly 14 with a distance sp between them. Also, the distal end of the upper composite leaf spring (i.e. upper beam 18) and the distal end of the lower composite leaf spring (i.e. lower beam 20) are mounted on aaxel support structure 16 with a distance sd between them. In this combination, sp and sd are equal to, or substantially equal to, each other. In any event, a coplanar relationship is established between theupper beam 18 and thelower beam 20. - Although the above disclosure has been focused primarily on a main landing gear assembly, the present invention also envisions its use for the manufacture of a nose gear assembly. In the case of a nose gear assembly, however, it is most likely that, rather than creating a
flexure unit 12, only one beam (e.g. a composite leaf spring) would be used. Further, although the above disclosure has also focused on retractable gear assemblies, it is to be appreciated that with minimal modifications the present invention can be just as well used for the manufacture of fixed gear assemblies. - While the particular Composite Twin Beam Main Landing Gear for an Aircraft as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.
Claims (20)
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US16/426,357 US11279474B2 (en) | 2019-05-30 | 2019-05-30 | Composite twin beam main landing gear for an aircraft |
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US1845162A (en) * | 1926-12-13 | 1932-02-16 | Lundelius & Eccleston Motors C | Spring suspension system |
US2319675A (en) | 1940-07-20 | 1943-05-18 | Goodrich Co B F | Loading patch for stress-testing aircraft |
US2394826A (en) * | 1944-07-12 | 1946-02-12 | Russell V Trader | Tail skid connection for airplanes |
US2413737A (en) | 1945-10-17 | 1947-01-07 | Edgar R Weaver | Adhesive tension patch |
US2534722A (en) * | 1947-01-10 | 1950-12-19 | Jr Thomas W Meiklejohn | Wheel suspension |
US2702188A (en) * | 1953-09-16 | 1955-02-15 | Chrysler Corp | Leaf spring interliner |
US3002742A (en) * | 1960-04-20 | 1961-10-03 | Troy Leonard | Vehicle suspension system |
US4986949A (en) | 1986-05-12 | 1991-01-22 | Trimble Brent J | Method of making composite bicycle frames |
US6482497B1 (en) | 1998-11-30 | 2002-11-19 | Rocky Mountain Composites Inc. | Pressure-cycled, packet-transfer infusion of resin-stitched preforms |
US6889937B2 (en) | 1999-11-18 | 2005-05-10 | Rocky Mountain Composites, Inc. | Single piece co-cure composite wing |
US7681835B2 (en) | 1999-11-18 | 2010-03-23 | Rocky Mountain Composites, Inc. | Single piece co-cure composite wing |
US6406580B1 (en) | 2000-06-09 | 2002-06-18 | Lockheed Martin Corporation | Method for manufacturing composite parts |
US6743504B1 (en) | 2001-03-01 | 2004-06-01 | Rohr, Inc. | Co-cured composite structures and method of making them |
US6616159B2 (en) * | 2001-05-22 | 2003-09-09 | Visteon Global Technologies, Inc. | Integrated rear wheel suspension system |
US8256710B2 (en) | 2007-09-14 | 2012-09-04 | Spectrum Aeronautical, Llc | Live trim tabs |
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