Abstract:
An aircraft designed to prevent foreign object damage to the aircraft. The aircraft includes an engine coupled aft of the aircraft&#39;s landing gear, and a deflecting member is coupled to the aircraft between the landing gear and an inlet of the engine so that when the deflecting member is extended, it intersects with a portion of lines of sight between the landing gear and an inlet of the engine.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to aircraft and more specifically to measures to prevent foreign object damage to aircraft. Even more specifically, the present invention relates to measures to prevent foreign object damage to an aircraft engine. 
   2. Discussion of the Related Art 
   Aircraft are susceptible to Foreign Object Damage (FOD) from various objects that impact the aircraft. For example, coins, personnel badges, loose hardware, tools, paper clips, pens, runway fragments, catering supplies, pieces of luggage, building materials, rocks, sand, hats, trash, and birds all potentially may inflict damage to an aircraft. 
   An aircraft&#39;s landing gear may project these objects at the aircraft or the landing gear may potentially become an airborne object itself. For example, when a potential FOD producing object is on a runway, the potential exists for aircraft landing gear, e.g., the aircraft&#39;s tires, to come in contact with the object. If the landing gear has impacted an object, the object itself may be projected off of the runway and towards the aircraft. It is also possible that pieces of the tire itself may be dislocated and be projected towards the aircraft. 
   Damage to the aircraft&#39;s jet engines is especially troublesome because performance of the jet engines is critical to safe flight. Thus, it is important to prevent as many objects as possible from becoming ingested jet engines. 
   SUMMARY OF THE INVENTION 
   In one embodiment, the invention can be characterized as an aircraft including: landing gear coupled to the aircraft, an engine coupled aft of the landing gear to the aircraft and a deflecting member coupled to the aircraft. The deflecting member includes an extended end and a mounting portion configured to couple with the aircraft, and the deflecting member is positioned between the landing gear and the engine so as to intersect with a portion of lines of sight between the landing gear and an inlet of the engine. 
   In another embodiment, the invention can be characterized as a method, and means for accomplishing the method, of preventing foreign objects from damaging an engine of an aircraft, the method including the steps of: extending a deflecting member to intersect a portion of lines of sight between landing gear of the aircraft and an inlet of the engine in response to the aircraft being in close proximity to a runway and retracting the deflecting member after the aircraft has become airborne. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein: 
       FIG. 1  is a is a top view of an aircraft illustrating exposure to an aircraft engine from FOD projecting from landing gear of the aircraft; 
       FIGS. 2A ,  2 B and  2 C are side, front and plan views respectively of the aircraft of  FIG. 1  employing a FOD flap to obstruct a least a portion of lines-of-sight between the landing gear and the engine in accordance with one embodiment of the present invention; 
       FIG. 3  is an alternative embodiment of the aircraft with an engine positioned aft of a trailing edge of a wing; and 
       FIG. 4  is a partial plan view of an aircraft illustrating a vertically mounted FOD flap in accordance with another embodiment of the present invention. 
     Corresponding reference characters indicate corresponding components throughout the several views of the drawings. 
   

   DETAILED DESCRIPTION 
   The following description is not to be taken in a limiting sense, but is made merely for the purpose of describing the general principles of the invention. The scope of the invention should be determined with reference to the claims. 
   Referring first to  FIG. 1 , shown is a top view of an aircraft illustrating exposure to an aircraft engine from FOD projecting from landing gear of the aircraft. Shown is an aircraft body  102 , an aircraft wing  104 , an aircraft engine  106 , an engine inlet  108 , landing gear  110  including a forward inboard tire  112 , a forward outboard tire  114  and an aft inboard tire  116 . Also shown is a line-of-sight zone  118  defined by an outboard line-of-sight boundary  120  and an inboard line-of-sight boundary  122 , and a threat zone  124  defined by an outboard threat zone boundary  126  and an inboard threat zone boundary  128 . 
   The aircraft wing  104  is coupled to the aircraft body  102 , the aircraft engine  106  is coupled to the aircraft wing  104  and the engine inlet  108  is located at a forward portion of the aircraft engine  106 . The landing gear  110  is shown directly below the aircraft wing  104 , and the landing gear includes the forward inboard tire  112 , forward outboard tire  114  and aft inboard tire  116 . The inboard line-of-sight boundary  122  is shown between a trailing and inboard edge of the aft inboard tire  116  and an inboard edge of the engine inlet  108 . The outboard line-of-sight boundary  120  is shown between a leading and outboard edge of the forward outboard tire  114  and an outboard portion of the engine inlet  108 . 
   The inboard threat zone boundary  128  is shown between a leading and inboard edge of the leading inboard tire and an outboard portion of the aircraft body  102 . The outboard threat zone boundary  126  is shown between a leading and outboard edge of the leading outboard tire  114  and a portion of the engine inlet  108  between the in board and outboard edge of the engine inlet  108 . The threat zone  124  is shown as an area between the inboard threat zone boundary  128  and the outboard threat zone boundary  126 . 
   As shown in  FIG. 1 , the aircraft engine  106  and the engine inlet  108  are located aft of the aircraft landing gear  110 ; thus exposing the aircraft engine  106  to debris that may be kicked up from the landing gear  110  during take-off and landing. In particular, the line-of-sight zone  118  which is an area comprising a collection of lines-of-sight between the inboard line-of-sight boundary  122  and the outboard line-of-sight boundary  120 , is a zone of higher risk from FOD as compared to FOD projecting from outside the line-of-sight zone  118  because the line-of-sight zone  118  is a collection of direct paths from the landing gear  110  to the engine inlet  108 . Although the line-of-sight zone  118  is shown in two dimensions in  FIG. 1 , it should be recognized that the line-of sight zone  118  is a three dimensional volume defined by lines-of-sight between outer edges of the engine inlet  108  and both an inboard edge of the aft inboard tire  116  and a leading and outboard edge of the forward outboard tire  114 . 
   The threat zone  124  is an area where there is an especially high risk of damage from FOD being projected from the landing gear  110  because the threat zone  124  includes an area directly behind the landing gear  110 . As shown, the threat zone  124  overlaps with the line-of-sight zone  118 , and the engine inlet  108  is within a portion of the threat zone  124 . Thus, the engine is generally susceptible to FOD because it is aft of and within lines-of-sight of the landing gear  110 , and the engine  106  is especially susceptible to FOD because at least a portion of the engine inlet  108  is within the threat zone  124 . 
   Obstructing at least a portion of the lines-of-sight between the landing gear  110  and the engine  106 , however, reduces the risk of FOD projected from the landing gear  110  entering the engine inlet  108 . Thus, according to several embodiments of the present invention a flap is employed to obstruct lines-of-sight, and hence FOD, emanating from the landing gear  110 . 
   Referring next to  FIGS. 2A ,  2 B and  2 C, for example, are shown are side, front and plan views respectively of the aircraft of  FIG. 1  employing a FOD flap to obstruct a least a portion of the lines-of-sight between the landing gear and the engine in accordance with one embodiment of the present invention. 
   Referring first to  FIG. 2A  shown are the landing gear  110 , the aircraft body  102 , the aircraft wing  104 , the line-of-sight zone  118  and the engine  106 . Also shown is a FOD flap  202  in a deployed position with an attached end  204  (also referred to as a mounting portion  204 ) coupled to the aircraft wing  104  forward of the engine  106 , and a free end  206  deployed below the aircraft wing  104  so that a forward face of the FOD flap  202  is interposed between the landing gear  110  and the engine  106 . Also shown with broken lines in the wing  104  is a stowed location  208  for the FOD flap  202 . 
   As shown in  FIG. 2A  the attached end  204  of FOD flap  202  in several embodiments is mounted mid-wing and along a substantially horizontal axis so that the free end  206  rotates about the substantially horizontal axis to intersect portions of the line-of-sight zone  118 . 
   In operation, the FOD flap  202  in several embodiments is extended (i.e., the free end  206  is rotated and/or telescopically extended) out to intersect with the line-of-sight zone  118  when the aircraft is in close proximity to a runway, e.g., during a landing approach or when taxiing on a runway. In some embodiments for example, the FOD flap  202  is extended to intersect upper and lower boundaries  210 ,  212  of the line-of-sight zone  118  when the aircraft is below a threshold elevation with respect to the ground plane  214 . 
   When there is a lower risk of FOD e.g., when the aircraft is airborne, the FOD flap  202  in several embodiments is retracted and positioned in the stowed location  208  which in the present embodiment is substantially parallel with the wing  104 . In this way the FOD flap  202  does not place unnecessary drag on the aircraft and does not interfere with a volume of air that must be pulled through the engine  106 . 
   In one embodiment, as shown in  FIG. 2B , the FOD flap  202  is sized and configured so that a forward side of the FOD flap  202  in a deployed position intersects the entire line-of-sight zone  118 . Thus, a view of the engine inlet  108  is completely obstructed when viewed from a location proximate the landing gear  110 . In this way, the IOD flap  202  helps to prevent a larger percentage of FOD as compared to embodiments where the FOD flap  202  intersects less that an entire cross section of the line-of-sight zone  118 . 
   As shown in  FIG. 2C , the FOD flap  202  according to several embodiments is positioned to obstruct a portion of the threat zone that overlaps with the inlet  108  of the engine  106 . Thus, the FOD flap  202  in these embodiments is positioned to intersect with a region of higher risk due to FOD that is kicked up, and/or generated from the landing gear  110 . 
   As shown in  FIGS. 2A ,  2 B and  2 C, the FOD flap  202  in several embodiments is mounted to the aircraft in a substantially horizontal position, i.e., the attached end  204  is mounted along a substantially horizontal axis, and when stowed, the FOD flap  202  is positioned substantially parallel with the wing  104 . 
   In some embodiments, portions of the FOD flap  202 , e.g., a deflecting surface, are deformable to absorb more energy from FOD, and thus, reduce the ability of the FOD to inflict damage to the engine  106  and/or other portions of the aircraft. For example, in one embodiment the FOD flap  202  is constructed from a composite of materials including, for example, Kevlar that deform upon contact with FOD. In another embodiment, the FOD flap  202  includes a mesh material on a forward facing surface of the FOD flap  202 . In yet another embodiment, the FOD flap  202  includes a net structure to help absorb energy of FOD impacting with the FOD flap  202 . 
   In additional embodiments, instead of rotating the free end  206  of the FOD flap  202  about the mounting portion  204  to extend the FOD flap  202  into the line-of-sight zone  118 , the FOD flap  202  is deployed in a telescopic fashion. One of ordinary skill in the art recognizes, however, that both telescopic and rotating means may be utilized to deploy a FOD flap and that such variations are well within the scope of the present invention. 
   Referring next to  FIG. 3 , shown is an alternative embodiment of the aircraft with an engine positioned aft of a trailing edge of a wing. Shown is an engine  302  positioned with respect to a wing  304  so that at least a portion of an inlet  306  of the engine  302  is aft of a trailing edge  303  of the wing. Also shown are landing gear  110  positioned forward of the engine  302  and forward of the trailing edge  303  of the wing  304 , and a FOD flap  308  is shown coupled with the wing  304  so that a free end  310  of the FOD flap  308  forms a portion of a trailing edge  303  of the wing when in a stowed position  312 . 
   As shown in  FIG. 3 , an attached end  314  (also referred to as a mounting portion  314 ) of the FOD flap  308  in the present embodiment is coupled with the aircraft wing  304  in a substantially horizontal manner so the when the FOD flap  308  is stowed, the forward face of the FOD flap  308  is positioned substantially parallel with the wing  304 . 
   In some embodiments, the FOD flap  308  is implemented by modifying main flaps already existing on an aircraft. Thus, in some embodiments, the FOD flap  308  helps provide lift to an aircraft when deployed, e.g., during takeoff and landing. 
   In operation, the FOD flap  308  in several embodiments is extended (i.e., the free end  310  is rotated and/or telescopically extended) out to intersect with a line-of-sight zone when the aircraft is in close proximity to a runway, e.g., during a landing approach or when taxiing on a runway. In some embodiments for example, the FOD flap  308  is extended when the aircraft is below a threshold elevation with respect to the ground plane  214 . 
   When there is a lower risk of FOD e.g., when the aircraft is airborne, the FOD flap  308  in several embodiments is retracted and positioned in the stowed location  312 . In this way the FOD flap  308  does not place unnecessary drag on the aircraft and does not interfere with the volume of air that must be pulled through the engine  302 . 
   Referring next to  FIG. 4 , shown is a partial plan view of an aircraft illustrating a vertically mounted FOD flap in accordance with another embodiment of the present invention. Shown are landing gear  402 , a line-of-sight zone  404 , a FOD flap  406  in a deployed position, a FOD flap cruise position  408 , an engine  410  and an engine inlet  412 . 
   The engine  410  is positioned aft of the landing gear  402  with the engine inlet  412  facing in a direction of the landing gear  402 , and the line-of-site zone  404  is shown as a region between an outboard line-of-sight boundary  414  and an inboard line-of sight boundary  416 . The outboard line of-sight boundary  414  is shown as a broken line between a forward and outboard portion of the landing gear  402  and an outboard portion of the engine inlet  412 , and the inboard line-of-sight boundary  416  is shown as a broken line between an inboard and aft portion of the landing gear  402  and an inboard portion of the engine inlet  412 . The FOD flap  406  is shown intersecting the line-of sight zone  404  with an attached end  418  proximate to an inboard portion of the engine inlet  412  and a free end  420  positioned forward of the engine inlet  412  and outboard of the inboard portion of the engine inlet  412 . 
   As shown in  FIG. 4 , the FOD flap  406  in the present embodiment is mounted so that a deflecting face  422  of the FOD flap is substantially perpendicular to the ground plane  214 , and the free and attached ends  420 ,  418  of the FOD flap  406  are substantially vertical with respect to the ground plane  214 . 
   In operation, when the aircraft is cruising, the FOD flap  406  in several embodiments is positioned in the FOD flap cruise position  408  that is substantially parallel with the direction of airflow to limit drag on the aircraft and allow the engine to draw unobstructed air. 
   When the aircraft is in close proximity to a runway, the FOD flap  406  in several embodiments is extended (i.e., the free end  420  is rotated out) to intersect with the line-of-sight zone  404 , and retracted (i.e., rotated back into the cruise position  408 ) when the aircraft is airborne. 
   While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.