Patent Publication Number: US-2007095977-A1

Title: Mesh fender for protecting an aircraft against damage from foreign objects

Description:
BACKGROUND OF THE INVENTION  
      The present invention relates to aircraft and, more particularly, to aircraft having a mesh fender for protecting the aircraft against foreign object damage.  
      Conventional aircraft are sometimes damaged when foreign objects laying on the runway are picked up by wheels of the aircraft during taxi and thrown at an airframe of the aircraft by the taxiing wheels. That is, when the aircraft wheels roll over debris, the debris is sometimes propelled toward the airframe as a result of, for example, being pinched between an edge of the wheel and the runway or being temporarily gripped by the wheel and then released toward the airframe. Examples of foreign objects are parts that have fallen off other aircraft and separated pieces of the runway.  
      One potential solution for protecting aircraft from foreign object damage is to remove foreign objects from the paths of taxiing aircraft. Although foreign object removal is an initiative at most airports, foreign objects are still often encountered by aircraft. Thus, efforts to remove all foreign objects cannot be relied on to protect aircraft from foreign object damage.  
      Another potential solution for protecting aircraft from foreign object damage is to make a skin of the airframe stronger than conventional airframe skins by making it of a stronger material and/or by making the skin thicker. However, stronger skin materials and/or thicker skins are undesirable because they are prohibitively costly and heavy.  
     BRIEF SUMMARY OF THE INVENTION  
      The present invention relates to aircraft comprising an airframe and landing gear including a wheel rotatably connected to the airframe. The landing gear further includes a fender connected to the airframe adjacent and generally above the wheel wherein the fender comprises a mesh having a plurality of openings.  
      In another aspect, the present invention relates to a fender for protecting a wheeled vehicle from damage caused by foreign objects propelled by a wheel of the vehicle. The fender comprises a mesh having a plurality of openings and is configured to connect to the vehicle adjacent and generally above the wheel.  
      In yet another aspect, the present invention relates to a method for protecting a wheeled vehicle from foreign objects propelled by a vehicle wheel. The method comprises positioning a mesh fender adjacent and generally above a vehicle wheel to block foreign objects propelled by the wheel. The fender has a plurality of openings.  
      Other aspects of the present invention will be in part apparent and in part pointed out hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective of an aircraft including landing gear having a fender according to a first embodiment of the present invention.  
       FIG. 2  is a perspective of the landing gear according to the present invention.  
       FIG. 3  is a perspective of landing gear including a fender according to a second embodiment of the present invention.  
       FIG. 4  is a perspective of landing gear including a fender according to a third embodiment of the present invention.  
       FIG. 5  is a perspective of landing gear including a fender according to a fourth embodiment of the present invention.  
       FIG. 6  is a perspective of landing gear including a fender according to a fifth embodiment of the present invention. 
    
    
      Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.  
     DETAILED DESCRIPTION OF THE INVENTION  
      Referring to the figures, and more particularly to  FIG. 1 , an aircraft according to a first embodiment of the present invention is designated in its entirety by reference number  10 . The aircraft  10  comprises an airframe  12  including a fuselage  14  and opposing wings  16  extending laterally from the fuselage. The aircraft  10  further comprises a landing gear assembly  18  including a strut  20  connected to an underside  22  of the airframe  12 , a wheel  24  rotatably connected to the strut, and a fender  26  connected to the strut adjacent and generally above the wheel. The fender  26  is positioned between the wheel  24  and the airframe  12  to protect the airframe from foreign objects propelled toward the airframe by the wheel. The landing gear assembly  18  may be directly connected to an underside  28  of one of the wings  16 . The aircraft  10  may include one or more (not shown) landing gear assemblies  18  connected to the wings  16  and/or fuselage  14 . Each landing gear assembly  18  may include more than one wheel  24 . For example, in one embodiment (not shown), a landing gear assembly includes two or more wheels mounted side-by-side and/or in tandem rotatably connected to a common strut between the wheels. In embodiments having such a multi-wheel landing gear assembly, a common fender may be positioned over the wheels or a separate fender may be positioned over each wheel. The fender  26  protects the aircraft  10  from damage caused by foreign objects “F” propelled toward the airframe  12  from the wheels  24 . Although the fender  26  is described as being part of an aircraft  10 , the fender may be part of other vehicles without departing from the scope of the present invention. For example, the fender  26  may be positioned over a wheel of an automobile (not shown).  
      As shown in  FIG. 2 , the fender  26  forms a mesh  30  having a plurality of openings  32 . Such a fender is said to be “vented.” There are many benefits to having a vented fender  26 . One benefit of having a vented fender  26  is weight reduction. That is, the fender  26  weighs less with the openings  32  than it would if it were made of the same material(s) but did not have openings. Another benefit of having a vented fender  26  is a reduction in drag compared to some solid fenders. Yet another benefit of having a vented fender  26  is that maintenance personnel can inspect the wheel  24  through the fender with relative ease. The mesh  30  includes a plurality of elongate members  34  forming the openings  32  between them. In one embodiment, the elongate members  34  may be integrally formed or formed by connecting separate components together. In one embodiment, the elongate members  34  include a foremost lateral member  36 , a rearmost lateral member  38 , and one or more intermediate lateral members  40 . The elongate members  34  further include a leftmost longitudinal member  42 , a rightmost longitudinal member  44 , and one or more intermediate longitudinal members  46  extending generally parallel to each other between the foremost and rearmost lateral members  36 ,  38 . The lateral members  36 ,  38 ,  40  extend generally parallel to each other between the leftmost and rightmost longitudinal members  42 ,  44 . In one embodiment, each lateral member  36 ,  38 ,  40  meets each longitudinal member  42 ,  44 ,  46  at an angle θ of about 90°, but the elongate members  34  may meet at other angles θ without departing from the scope of the present invention. The intermediate lateral members  40  intersect the intermediate longitudinal members  46 . The mesh  30  may be configured in other ways without departing from the scope of the present invention. For example, in one embodiment (not shown), elongate members crisscross along diagonals. In another embodiment (not shown), the members  34  form a honeycomb arrangement by forming a plurality of hexagons having common sides.  
      Whichever mesh  30  configuration is used, the elongate members  34  should be shaped and spaced from each other by distances large enough to allow personnel to easily inspect the underlying landing gear. As will be appreciated by those skilled in the art, variables affecting mesh  30  material, shape, dimensions, and positioning include materials, shapes, sizes, and velocities of foreign objects F expected to be propelled toward the airframe  12 . For example, the mesh  30  should be made stronger when heavier objects made of harder materials are expected to be hurled at higher speeds toward the airframe  12 . The mesh  30  may be tailored to ensure that foreign objects F of particular sizes and shapes will not pass through the mesh. The mesh  30  may also be tailored to allow certain foreign objects F to pass through the mesh in a controlled manner. For example, the mesh  30  may be shaped and made of a material allowing foreign objects F of a particular material and within a particular size hurled toward the airframe  12  at a particular velocity to break through the mesh as a whole or pass through the mesh after being broken into pieces by the mesh. The mesh  30  is effective to protect the airframe  12  even when the foreign object F passes through the mesh because the mesh decreases the kinetic energy of the object as the object passes through so that the airframe is not damaged. If the mesh  30  breaks while slowing the object F, the mesh  30  or entire fender  26  can be replaced during maintenance.  
      Each elongate member  34  has a top  48 , a bottom  50 , and opposing sides  52 . Although the elongate members  34  may have other heights  54  extending between their respective tops  48  and bottoms  50  without departing from the scope of the present invention, in one embodiment each elongate member has a height between about 1 centimeter and about 8 centimeters. Although the elongate members  34  may have other widths  56  without departing from the scope of the present invention, in one embodiment each elongate member has a width of between about 0.30 centimeters and about 1.30 centimeters. The elongate members  34  may have various height-to-width ratios without departing from the scope of the present invention. For example, in one embodiment each member  34  has a height-to-width ratio of at least 2:1 and in another embodiment the ratio is at least 4:1 or more. The mesh openings  32  can have various dimensions without departing from the scope of the present invention. For example, in one embodiment each opening  32  has a length  58  of between about 10 centimeters and about 30 centimeters and a width  60  of between about 2 centimeters and about 13 centimeters.  
      Although the mesh  30  may be made of other materials without departing from the scope of the present invention, in one embodiment the mesh is made of stainless steel. Primary considerations for selecting mesh  30  material include fender weight and strength. The mesh  30  may also be made of more than one material. For example, in one embodiment the foremost and rearmost lateral members  36 ,  38  are made of a material, such as steel, that is more rigid than a material, such as aluminum, that the intermediate lateral members  40  and longitudinal members  42 ,  44 ,  46  are made of. In this embodiment, the more rigid members  36 ,  38  resist deformation to provide framing support to the mesh  30  while the less rigid members  40 ,  42 ,  44 ,  46  allow a predetermined higher amount of deformation than the more rigid members when hit with a foreign object F to absorb the kinetic energy of the object. In addition, the foremost and the rearmost lateral members  36 ,  38  may be shaped to be stronger, such as by forming tubes (shown in  FIG. 6 ).  
      In one embodiment, the mesh  30  is curved and has an inner radius of curvature R adapted for receiving the wheel  24 . Although the mesh  30  may have other radii of curvature R, in one embodiment the mesh has a radius of curvature of between about 20 centimeters and about 75 centimeters. The radii of curvature R may be equal to a distance D between a rotation axis A of the wheel  24  and the mesh  30 . Although the mesh  30  may have other widths  62  extending between a left side  64  of the mesh and a right side  66  of the mesh, in one embodiment the mesh has a width of between about 2 centimeters and about 13 centimeters. Although the mesh  30  may have other lengths  68  extending between a forward end  70  of the mesh and an aft end  72  of the mesh, in one embodiment the mesh has a length of between about 10 centimeters and about 30 centimeters. In one embodiment, the mesh  30  is generally cylindrical to permit replacement of the wheel  24  without interference from the fender  26 . One of the variables determining mesh width  62 , length  68 , shape, and positioning is desired coverage area. That is, the fender  26  is be sized, shaped, and positioned to protect a predetermined portion of the aircraft  10  above the mesh  30 . For example, in one embodiment the primary purpose of the fender  26  is to protect a particularly sensitive portion (not identified in the figures) of the underside  28  of the wing that is generally above and behind the fender. Thus, in this embodiment, the fender  26  may be shifted rearward, made shorter on the forward end  70 , and/or made longer on the aft end  72 . Similarly, the width  62  of the fender  26  can be tailored and/or the fender can be laterally shifted to ensure protection of a predetermined portion of the aircraft  10 .  
      The fender  26  may be configured in various ways for connection to the airframe  12 . For example, as shown in  FIG. 2 , the mesh  30  may be connected to the strut  20  by way of one or more links  74 . The links  74  can be connected to the mesh  30  and the strut  20  in a variety of ways without departing from the scope of the present invention. For example, the links  74  can be welded or bolted to the strut  20  and mesh  30 . In one embodiment, the links  74  are integrally formed with the mesh  30 . It is contemplated that the strut-side longitudinal mesh member  44  may be made of a stronger material than the other longitudinal members  42 ,  46  to ensure a strong connection between the mesh  30  and the strut  20 .  
       FIG. 3  shows an embodiment of the present invention wherein a mesh  80  of a fender  82  includes holes  84  in longitudinal members  86  to receive support bars  88  that are connected to a strut  20 .  FIG. 4  shows an embodiment of the present invention wherein the longitudinal members  90  extend longitudinally in front of a foremost lateral member  92  and behind a rearmost lateral member  94  and have holes  96  formed in the extended portions for receiving the support bars  88 . When holes  84 ,  96  are formed in longitudinal members  86 ,  90  for receiving the support bars  88 , it is contemplated that the longitudinal members may be reinforced or made stronger around the holes to strengthen the mesh-to-strut connection.  FIG. 5  shows an embodiment of the present invention wherein one or more brackets  100  having cavities  102  are mounted on a foremost lateral member  104  and a rearmost lateral member  106  for receiving the support bars  88 .  FIG. 6  shows an embodiment of the present invention wherein a foremost lateral member  110  and a rearmost lateral members  112  each form a sleeve having a cavity  114  for receiving the support bars  88 . In each embodiment wherein the mesh is connected to support bars  88 , adjustable or immovable inside collars  116  can be positioned on the support bars inside of the mesh  118  (i.e., on a side of the mesh adjacent the strut  20 ) and removable or permanent outside collars  120  can be positioned on the support bars outside of the mesh (i.e., on a side of the mesh opposite the strut  20 ). Adjustable inside collars  116  allow flexibility in mesh  118  positioning in the lateral direction. Removable outside collars  120  facilitate mesh  118  installation, removal for replacement, and temporary removal for, for example, a detailed analysis of the wheel  24  by maintenance personnel. As will be appreciated by skilled artisans, the collars  116 ,  120  can be any of many types of securing arrangements. For example, the collars  116 ,  120  can include pins that are secured in holes (not shown) in the bars  88  to fasten the mesh  118  in place.  
      The aircraft may be configured so the landing gear assembly is retractable (not shown in detail) into the airframe to improve aerodynamic characteristics of the aircraft during flight between take-off and landing. In one embodiment, the fender is positioned close to the wheel to allow retrofit or manufacture of the fender on conventional retractable aircraft landing gear assemblies. In one embodiment (not shown in detail), the fender is movable, such as pivotable, with respect to the landing gear strut to facilitate retraction and storage of the landing gear assembly in the airframe when retracted.  
      When introducing elements of the present invention or the preferred embodiment(s) thereof, the articles “a”, “an”, “the”, and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including”, and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.  
      As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.