Patent Document

FIELD OF THE INVENTION 
   The claimed invention relates generally to the field of aviation and more particularly, but not by way of limitation, to a method and apparatus for improved flight dynamics for an aircraft. 
   BACKGROUND 
   The optimization of flight dynamics for an aircraft is an important task typically undertaken by aeronautical engineers during the development and testing phases involved in bringing an aircraft to market. Following development, testing, and certification phases of the Series 20 LEARJET®, the aircraft was introduced to the market in 1964, and was followed by the introduction of the Series 30 LEARJET® in 1974. 
   The handling characteristics of LEARJET® Series 20 and 30 yield aircraft that is fairly complex to fly, which in the number of applications necessitates the presence of two pilots during flight. The drag acting on aircraft, the available lift provided by the wings, and available thrust provided by the engines each contribute to the aircraft&#39;s operating efficiency and its ability to take off, land, and avoid a stall condition during flight. 
   Two conditions known to be present in LEARJET® Series 20 and 30 aircraft from their introduction to the present are, their susceptibility of encountering a stall condition, and the susceptibility of the aircraft to dip its nose when additional thrust is provided during flight. 
   Accordingly, there is a long felt need for improvements in the flight dynamics of LEARJET® Series 20 and 30 aircraft. 
   SUMMARY OF THE INVENTION 
   In accordance with a preferred embodiment, an aircraft includes at least a fuselage supporting a wing, an engine for propelling said aircraft, and a pylon disposed between said engine and said fuselage and securing said engine to said fuselage, wherein said pylon provides an airfoil inverted from an airfoil of said wing. 
   In accordance with a preferred embodiment, an improvement for an aircraft selected from a group consisting of 20 Series and 30 Series LEARJET® that preferably includes at least increasing the horizontal distance between the leading edge of a wing of the selected aircraft and an intake of an engine of the selected aircraft. The increased horizontal separation between the leading edge of the wing and the intake of the engine reduces drag and increases lift provided by the wing for improved flight dynamics of the selected aircraft. The improvement preferably further includes a pylon (for use in securing the engine to the fuselage) that provides an airfoil inverted in form from a form of an airfoil provided by the wing. The inverted airfoil neutralizes the effect of the pylon, relative to lift and drag, for improved flight dynamic of the aircraft. 
   For the 20 Series LEARJET®, the preferred embodiment also preferably includes, the engine secured to the pylon such that a centerline passing through the engine is substantially parallel to a waterline of the aircraft. The substantially parallel alignment between the engine centerline and said waterline reduces drag effecting said aircraft flight dynamics. An increased distance between the centerline of the engine and the waterline of the aircraft is preferably incorporated within the improvement to increase lift provided by the wings of the aircraft, and an increased distance between the centerline of said engine and a centerline of the fuselage is included in the improvement to reduce drag effecting the flight dynamics of the aircraft. 
   In accordance with an alternate preferred embodiment, a method of improving flight dynamics of an aircraft selected from a group consisting of (a 20 Series LEARJET® and a 30 Series LEARJET®) is provided by steps that preferably include: removing an original engine from an original pylon of the aircraft; removing the original pylon from an original location adjacent a fuselage of the aircraft; and mounting a new pylon in a new location adjacent the fuselage, wherein the new location is located aft of said original location. 
   The alternate preferred embodiment preferably further includes the step of mounting a new engine to the new pylon such that the distance between a centerline of the new engine (which runs substantially parallel to the waterline) and the waterline of the aircraft is greater than a distance between a central point along a centerline of the original engine and the waterline. The alternate preferred embodiment also preferably further includes the steps of: mounting the new engine on the new pylon such that a distance between a centerline of the new engine and a centerline of the fuselage is greater than a distance between a centerline of the original engine and the centerline of the fuselage; and covering the pylon with a skin, wherein the skin provides an airfoil inverted in shape relative to an airfoil shape provided by the wing of said aircraft. 
   These and various other features and advantages, which characterize preferred embodiments of the present invention, will be apparent from reading the following detailed description in conjunction with reviewing the associated drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a top plan view of prior art aircraft applicable to the present invention. 
       FIG. 2  provides a side elevational view of the prior art aircraft of  FIG. 1 . 
       FIG. 3  provides a front elevational view of the prior art aircraft of  FIG. 1 . 
       FIG. 4  is a top plan view of an aircraft of the present invention. 
       FIG. 5  provides a side elevational view of the aircraft of  FIG. 4 . 
       FIG. 6  provides a front elevational view of the aircraft of  FIG. 4 . 
       FIG. 7  shows a partial cross-sectional, side elevational view of a pylon and a wing of the aircraft of  FIG. 4 . 
       FIG. 8  is a diagram of a flowchart of a method of making the present invention. 
   

   DETAILED DESCRIPTION 
   Reference will now be made in detail to one or more examples of the invention depicted in the accompanying figures. Each example is provided by way of explanation of the invention, and are not meant as, nor do they represent, limitations of the invention. For example, features illustrated or described as part of one embodiment may be used with another embodiment to yield still a different embodiment. Other modifications and variations to the described embodiments are also contemplated and lie within the scope and spirit of the invention. 
   Referring to the drawings, to provide an enhanced understanding of the present invention, a reader is encouraged to view prior art  FIGS. 1 ,  2 , and  3  in concert while proceeding with reading this description of the present invention. Collectively, prior art 
     FIGS. 1 ,  2 , and  3  depict prior art 20 and 30 Series LEARJET® aircraft applicable for use with the present invention. 
   Prior art  FIG. 1  is useful for presenting a plan view of both a prior art 20 Series Learjet aircraft and a prior art 30 Series LEARJET® (collectively prior art aircraft  10 ) found useful in practicing the present invention. Prior art  FIG. 2  shows the prior art aircraft  10 , in side elevational view, for a prior art 20 Series LEARJET® aircraft, and prior art  FIG. 3  shows the front elevational view suitable for depicting either the 20 or 30 Series prior art LEARJET® aircraft. When collectively viewing prior art  FIGS. 1 ,  2 , and  3 , the reader&#39;s attention is drawn to the location of the engines  12 , relative to other sections and references of the aircraft, and in particular to the nacelle  13  inclosing each engine  12 . 
   Prior art  FIG. 1  shows that engine inlets  14 , of the engines  12 , are correspondingly positioned at a predetermined distance  16  (of about 153 centimeters) from a corresponding leading edge  18 , of their corresponding wings  20 , and that each engine  12  is secured to a fuselage  22 , of the prior art aircraft  10  by a pylon  24 . Prior art  FIG. 1  further shows centers of mass  26 , of the engines  12 , are correspondingly positioned at a predetermined distance  28  (of about 111 centimeters) from a centerline  30 , of the fuselage  22 , of the prior art aircraft  10 . 
   The prior art aircraft  10 , of  FIG. 2 , depicts an orientation of the engine  12 , for a prior art 20 Series LEARJET® aircraft relative to the fuselage  22  via the relationship between a centerline  32  of the engine  12 , and a waterline  34  of the prior art aircraft  10 . In the prior art 20 Series LEARJET®; the engine  12  is set at a predetermined pitch angle  36  (of about 3°). That is, the engine  12  slopes from the engine inlet  14  to an engine outlet  38  at about a three-degree angle. Prior art  FIG. 2  also shows the center of mass  26 , of the engine  12 , is positioned at a predetermined distance (of about 101 centimeters) from the waterline  34 . 
   For both the 20 and 30 Series prior art LEARJET® shown by  FIG. 3 , nacelles  42  and fuselage skin  44  appear to abut one another. However, by referring back to  FIG. 1 , it can be seen that the engines  12  are offset from the fuselage  22  by the pylons  24 . Nonetheless,  FIG. 1  shows that a portion of the fuselage skin  44  and a portion of the nacelle  42  of the engine  40  lie coextensively with a cord line  46  (of  FIG. 1 ). 
   The position of the engines  12  of the prior art aircraft  10  relative to the wings  20  and the fuselage  22  has a direct bearing on the flight dynamics of prior art aircraft  10 . The location of the engines  12 , relative to the wings  20  creates a partial air dam between wings  20  and the engines  12 . The effect of this partial air dam is a disruption in the fluid flow over the wings  20 , which decrease the effectiveness of the wings  20 . In other words, by partially disrupting the flow of fluid over the wing, the amount of available lift provided by the wing is diminished. The diminished availability of lift provided by wings  20  reduces the ability of prior art aircraft  10  to avoid stall conditions during flight. 
   The spacing of the engines  12 , relative to the fuselage  22  also creates a partial air dam for fluid flowing between the fuselage  22  and the engines  12 . The result of this disruption in fluid flow is an increase in the overall drag experienced by the prior art aircraft  10 . 
   For the 20 Series prior art LEARJET®, the problem of reduced lift capability of the wings  20  and increased drag created between the fuselage  22  in the engines  12  is exasperated by having the engines  12  mountain at a 3° pitch, relative to the waterline  34 . Mounting the engines  12  at a 3° pitch relative to the waterline  34  introduces additional drag and difficult handling characteristics into the flight dynamics of the prior art aircraft  10 . In addition to the increase in drag, the 3° pitch further affects the flight dynamics of the 20 Series LEARJET® by causing the nose of the prior art aircraft  10  to dip when additional throttle is applied to the engines  12  of the 20 Series LEARJET® during flight. 
   For ease in contrasting the present invention with the prior art,  FIGS. 4 ,  5 , and  6  are provided to depict the present invention in views comparable to  FIGS. 1 ,  2 , and  3 . Accordingly, viewing  FIGS. 4 ,  5 , and  6  together will provide an enhanced understanding of the present invention. Collectively,  FIGS. 4 ,  5 , and  6  depict structural changes made to the 20 and 30 Series LEARJET® aircraft to produce an improved present inventive aircraft  100 .  FIG. 4  presents a plan view of an inventive aircraft  100  and is useful for showing a change in engine location between the prior art aircraft  10  (of  FIG. 1 ) and the inventive aircraft  100 .  FIG. 5  shows the inventive aircraft  100  in side elevational view, which is useful in helping with an understanding of a structural change made to the 20 Series LEARJET® in arriving at the present inventive aircraft  100 .  FIG. 6  shows the front elevational view of the inventive aircraft  100  suitable for depicting an additional structural change employed in arriving at the present inventive aircraft  100 . When collectively viewing  FIGS. 4 ,  5 , and  6 , the reader&#39;s attention is drawn to the location of the engines  102 , relative to other sections and references of the inventive aircraft  100 . 
   In a preferred embodiment shown by  FIG. 4 , engine inlets  104  of the engines  102 , are preferably positioned at a distance  106  (of about 194 centimeters) from corresponding leading edges  108  of corresponding wings  110 . Each engine  102  is preferably secured to a fuselage  112  by a pylon  114 .  FIG. 4  further shows centers of mass  116 , of the engines  102 , are preferably correspondingly positioned at a distance  118  (of about 121.5 centimeters) from a centerline  120 , of the fuselage  112  of the inventive aircraft  100 . 
   The inventive aircraft  100  of  FIG. 5  shows an orientation of the engine  102  (for an inventive aircraft  100  based on a 20 Series LEARJET®) relative to a centerline  122  of the engine  102 , and a waterline  124  of the inventive aircraft  100 . In the 20 Series LEARJET® prior art aircraft  10  (of  FIG.2 ), the engine  12  is set at a downwardly sloping 3° pitch. In a preferred embodiment shown by  FIG. 5 , the relationship between the centerline  122  and the waterline  124  shows an absence of a pitch, i.e., the centerline  122  lies substantially parallel to the waterline  124 .  FIG. 5  also shows the center of mass  116 , of the engine  102 , is positioned at a selected distance  126  (of about 109 centimeters) from the waterline  124 . 
   In a preferred embodiment of the inventive aircraft  100  shown by  FIG. 6 , nacelles  128  are offset from a fuselage skin  130  such that a portion of the pylons  114  are brought into view when viewing the inventive aircraft  100  from a front elevational perspective. By referring back to  FIG. 4 , it can be seen that the engines  102  are offset from the fuselage  112  by the pylons  114  at a distance sufficient to assure that the nacelle  128  does not lie coextensively with a cord line  132 , which lies tangent to the fuselage skin  130 . 
   The position of the engines  102  of the inventive aircraft  100  relative to the wings  110  and the fuselage  112  has a direct bearing on improved flight dynamics of the inventive aircraft  100 , when compared to the flight dynamics of the prior art aircraft  10  (of  FIGS. 1-3 ). The location of the engines  102 , relative to the wings  110  alleviates the partial air dam present between wings  20  in the engines  12  of the prior art aircraft  10 . By alleviating the air dam, the amount of available lift provided by the wings  110  is greatly enhanced. The spacing of the engines  102 , relative to the fuselage  112  removes from the inventive aircraft  100  the partial air dam developed between the fuselage  22  in the engines  12  of prior art aircraft  10 , which decreases the overall drag experienced by the inventive aircraft  100 . 
   For the inventive aircraft  100  based on the 20 Series LEARJET®, removing the 3° pitch of the engines  12 , relative to the waterline  34  on the prior art aircraft  10  (of  FIG. 2 ), alleviates the drag created by the 3° pitch, and the tendency of the nose to dip during in flight accelerations. 
   In a preferred embodiment, the following dimensional changes for engine location have been found useful in providing the inventive aircraft  100  based on either the 20 or 30 Series LEARJET®. Those dimensional changes for engine location include positioning the engines  102 : about 41 centimeters further back from the leading edge  108  of the wing  110  at a point adjacent the fuselage  112 ; about 8 centimeters further up from the waterline  124 ; and about 10.2 centimeters further out from the fuselage centerline  120 . It has been found that these improvements dramatically improve the flight dynamics of the inventive aircraft  100 , relative to the flight dynamics of the prior art aircraft  10 . The improvement includes a greatly enhanced ability to avoid stall conditions during in flight maneuvers. 
     FIG. 7  shows that in a preferred embodiment of the present invention, an airfoil  134  is provided by a skin  136  of the pylon  114 . Preferably, the shape of the airfoil  134  is inverted in form from the shape of an airfoil  138  provided by the wing  110 . By presenting the airfoil  134  to an air stream in an orientation inverted from the airfoil  138  of the wing  110 , an influence of the pylon  114  on the flight dynamics of the inventive aircraft  100  is neutralized. That is to say, by providing an inverted airfoil  134  covering the pylon  114 , the pylon  114  neither adds to the drag nor detracts from the lift of the inventive aircraft  100 . The shape of the airfoil of the pylon, i.e., inverted from the shape of the airfoil of the wing, has removed Io the pylon as a structural component effecting the aerodynamics of the aircraft. 
   Turning to  FIG. 8 , the flow chart  200  depicts a process of forming an inventive aircraft (such as  100 ). The method commences at start step  202  and proceeds to process step  204  with the removal of an engine (such as  12 ). At process step  206 , a pylon (such as  24 ) is removed from a fuselage (such as  22 ) of the inventive aircraft. Following the removal of the pylon from the fuselage; providing a portion of fuselage skin (such as  44 ) to cover the portion of the fuselage left open by removal of the pylon; and removing a portion of fuselage skin from the airframe in preparation for mounting a new pylon (such as  114 ), the new pylon is secured to the fuselage at process step  208 . 
   At process step  210 , a new engine (such as  102 ) is mounted to the new pylon. At process step  212 , the new pylon is covered with a skin (such as  136 ) to provide an airfoil (such as  134 ) and the process concludes at end process step  214 . 
   It is to be understood that even though numerous characteristics and advantages of various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and function thereof, this detailed description is illustrative only, and changes may be made in detail, especially in matters of structure and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. For example, the particular elements may vary depending on the particular application for a select engine, while maintaining the same functionality without departing from the spirit and scope of the invention.

Technology Category: 7