Abstract:
A fan blade comprises an airfoil profile having a lower surface, an upper surface, a trailing edge, and a leading edge. The lower surface comprises a concave portion which is defined by a first ellipse. The upper surface comprises a convex portion which is defined by a second ellipse. The leading edge and the trailing edge are of a substantially convex shape and transition the concave shape of the lower surface to the convex shape of the upper surface. A maximum thickness of the airfoil profile is defined at a point along the airfoil profile proximal to the leading edge of the fan blade. A chord length is defined as a lineal distance between an outermost point of the leading edge and an outermost point of the trailing edge. The dimensions of the airfoil profile, including those of the first ellipse and second ellipse, are functions of the chord length.

Description:
[0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/619,468, entitled “Airfoil for Fan Blade,” filed Apr. 3, 2012, the disclosure of which is incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    This disclosure relates to fans and, more particularly to a fan blade having an airfoil profile. 
       BACKGROUND 
       [0003]    A variety of fan systems have been made and used over the years in a variety of contexts. For instance, various ceiling fans are disclosed in U.S. Pat. No. 7,284,960, entitled “Fan Blades,” issued Oct. 23, 2007; U.S. Pat. No. 6,244,821, entitled “Low Speed Cooling Fan,” issued Jun. 12, 2001; U.S. Pat. No. 6,939,108, entitled “Cooling Fan with Reinforced Blade,” issued Sep. 6, 2005; and U.S. Pat. No. D607,988, entitled “Ceiling Fan,” issued Jan. 12, 2010. The disclosures of each of those U.S. patents are incorporated by reference herein. Additional exemplary fans are disclosed in U.S. Pat. No. 8,079,823, entitled “Fan Blades,” issued Dec. 20, 2011; U.S. Pat. Pub. No. 2009/0208333, entitled “Ceiling Fan System with Brushless Motor,” published Aug. 20, 2009; and U.S. Pat. Pub. No. 2010/0278637, entitled “Ceiling Fan with Variable Blade Pitch and Variable Speed Control,” published Nov. 4, 2010, the disclosures of which are also incorporated by reference herein. It should be understood that teachings herein may be incorporated into any of the fans described in any of the above-referenced patents, publications, or patent applications 
         [0004]    A fan blade or airfoil may include one or more upper air fences and/or one or more lower air fences at any suitable position(s) along the length of the fan blade or airfoil. Merely exemplary air fences are described in U.S. Pat. Pub. No. 2011/0081246, entitled “Air Fence for Fan Blade,” published Apr. 7, 2011, the disclosure of which is incorporated by reference herein. Alternatively, any other suitable type of component or feature may be positioned along the length of a fan blade or airfoil; or such components or features may simply be omitted. 
         [0005]    The outer tip of a fan blade or airfoil may be finished by the addition of an aerodynamic tip or winglet. Merely exemplary winglets are described in U.S. Pat. No. 7,252,478, entitled “Fan Blade Modifications,” issued Aug. 7, 2007, the disclosure of which is incorporated by reference herein. Additional winglets are described in U.S. Pat. No. 7,934,907, entitled “Cuffed Fan Blade Modifications,” issued May 3, 2011, the disclosure of which is incorporated by reference herein. Still other exemplary winglets are described in U.S. Pat. No. D587,799, entitled “Winglet for a Fan Blade,” issued Mar. 3, 2009, the disclosure of which is incorporated by reference herein. In some settings, such winglets may interrupt the outward flow of air at the tip of a fan blade, redirecting the flow to cause the air to pass over the fan blade in a perpendicular direction, and also ensuring that the entire air stream exits over the trailing edge of the fan blade and reducing tip vortex formation. In some settings, this may result in increased efficiency in operation in the region of the tip of the fan blade. In other variations, an angled extension may be added to a fan blade or airfoil, such as the angled airfoil extensions described in U.S. Pat. Pub. No. 2008/0213097, entitled “Angled Airfoil Extension for Fan Blade,” published Sep. 4, 2008, and issued Apr. 24, 2012 as U.S. Pat. No. 8,162,613, the disclosure of which is incorporated by reference herein. Other suitable structures that may be associated with an outer tip of an airfoil or fan blade will be apparent to those of ordinary skill in the art. Alternatively, the outer tip of an airfoil or fan blade may be simply closed (e.g., with a cap or otherwise, etc.), or may lack any similar structure at all. 
         [0006]    The interface of a fan blade and a fan hub may also be provided in a variety of ways. For instance, various interfaces are described in U.S. Pat. Pub. No. 2009/0081045, entitled “Aerodynamic Interface Component for Fan Blade,” published Mar. 26, 2009, and issued Apr. 3, 2012 as U.S. Pat. No. 8,147,204; and U.S. Provisional Patent Application No. 61/590,469, entitled “Fan with Resilient Hub,” filed Jan. 25, 2012, the disclosure of which is incorporated by reference herein. In addition, or in the alternative, the fan blade may include a retention system that couples the tip of a fan blade to an attachment point on the fan hub via a cable running through the fan blade, such as that disclosed in U.S. Pat. Pub. No. 2011/0262278, entitled “Fan Blade Retention System,” published Oct. 27, 2011. Alternatively, the interface of a fan blade and a fan hub may include any other component or components, or may lack any similar structure at all. 
         [0007]    Fans may also include a variety of mounting structures. For instance, a fan mounting structure is disclosed in U.S. Pat. Pub. No. 2009/0072108, entitled “Ceiling Fan with Angled Mounting,” published Mar. 19, 2009, and issue Apr. 10, 2012 as U.S. Pat. No. 8,152,453, the disclosure of which is incorporated herein. Of course, a fan need not be mounted to a ceiling or other overhead structure, and instead may be mounted to a wall or to the ground. For instance, a fan may be supported on the top of a post that extends upwardly from the ground. Alternatively, any other suitable mounting structures and/or mounting techniques may be used in conjunction with embodiments described herein. 
         [0008]    It should also be understood that a fan may include sensors or other features that are used to control, at least in part, operation of a fan system. For instance, such fan systems are disclosed in U.S. Pat. Pub. No. 2009/0097975, entitled “Ceiling Fan with Concentric Stationary Tube and Power-Down Features,” published Apr. 16, 2009, and issued Apr. 3, 2012 as U.S. Pat. No. 8,147,182, the disclosure of which is incorporated by reference herein; U.S. Pat. Pub. No. 2009/0162197, entitled “Automatic Control System and Method to Minimize Oscillation in Ceiling Fans,” published Jun. 25, 2009, and issued Feb. 28, 2012 as U.S. Pat. No. 8,123,479, the disclosure of which is incorporated by reference herein; U.S. Pat. Pub. No. 2010/0291858, entitled “Automatic Control System for Ceiling Fan Based on Temperature Differentials,” published Nov. 18, 2010, the disclosure of which is incorporated by reference herein; and U.S. Provisional Patent Application No. 61/165,582, entitled “Fan with Impact Avoidance System Using Infrared,” filed Apr. 1, 2009, the disclosure of which is incorporated by reference herein. Alternatively, any other suitable control systems/features may be used in conjunction with embodiments described herein. 
         [0009]    While several systems and methods have been made and used for ceiling fan blades, it is believed that no one prior to the inventors has made or used the invention described in the appended claims. 
       SUMMARY 
       [0010]    One aspect of the present disclosure relates to a fan blade having an airfoil profile for a rotating fan hub. The airfoil profile includes a lower surface having a concave portion and an upper surface having a convex portion. The airfoil profile further includes a leading edge, wherein the leading edge is of a substantially convex shape and a trailing edge, wherein the trailing edge is of a substantially convex shape. The concave portion of the lower surface may extend between a first point and a second point. The convex portion of the upper surface may extend between a third point and a fourth point. 
         [0011]    In one embodiment, the maximum thickness of the airfoil profile is defined at a first point along the airfoil profile. The leading edge may extend between the first point of the lower surface and the third point of the upper surface while the trailing edge may extend between the second point of the lower surface and the fourth point of the upper surface. The airfoil profile may also include a chord length (c), wherein the chord length is defined by a lineal distance from an outermost point of the leading edge to an outermost point of the trailing edge. The concave portion of the lower surface may be defined by a first ellipse while the convex portion of the upper surface may be defined by a second ellipse. 
         [0012]    Another aspect of this disclosure relates to a fan blade configured to mount to a rotating fan hub. The fan includes an airfoil profile having a lower surface, wherein the lower surface has a concave portion extending between a first point and a second point, and wherein a maximum thickness of the airfoil profile is defined at the first point along the airfoil profile and an upper surface, wherein the upper surface comprises a convex portion extending between a third point and a fourth point. The airfoil profile further includes a leading edge, wherein the leading edge is of a substantially convex shape, and wherein the leading edge extends between the first point of the lower surface and the third point of the upper surface and a trailing edge, wherein the trailing edge is of a substantially convex shape, and wherein the trailing edge extends between the second point of the lower surface and the fourth point of the upper surface. Finally, the airfoil profile has a chord length (c), wherein the chord length is defined by a lineal distance from an outermost point of the leading edge to an outermost point of the trailing edge. 
         [0013]    In one embodiment, a radius of the substantially convex shape of the leading edge varies from the first point of the lower surface to the third point of the upper surface. Furthermore, the first point may be located a distance of about 0.724 c away from the trailing edge of the air foil profile and along the chord length while the third point may be located a distance of about 0.776 c away from the trailing edge of the air foil profile and along the chord length. A portion of the leading edge surrounding the outermost point of the leading edge may have a radius of about 0.06 c. A radius of the substantially convex shape of the trailing edge may vary from the second point of the lower surface to the further point of the upper surface. 
         [0014]    In accordance with another aspect of the disclosure, a fan blade having an airfoil profile is disclosed. The airfoil profile includes a lower surface, wherein the lower surface comprises a concave portion extending between a first point and a second point, wherein the concave portion of the lower surface is defined by a first ellipse, and wherein a maximum thickness of the airfoil profile is defined at the first point along the airfoil profile. The airfoil profile also has an upper surface, wherein the upper surface comprises a convex portion extending between a third point and a fourth point, and wherein the convex portion of the upper surface is defined by a second ellipse. The airfoil profile further has a leading edge, wherein the leading edge is of a substantially convex shape, wherein the leading edge extends between the first point of the lower surface and the third point of the upper surface, and wherein a radius of the substantially convex shape of the leading edge varies from the first point of the lower surface to the third point of the upper surface and a trailing edge, wherein the trailing edge is of a substantially convex shape, wherein the trailing edge extends between the second point of the lower surface and the fourth point of the upper surface, and wherein a radius of the substantially convex shape of the trailing edge varies from the second point of the lower surface to the fourth point of the upper surface. 
         [0015]    A further aspect of the disclosure relates to a fan assembly. The fan assembly includes a fan motor, a fan hub, wherein the fan hub is couple to the fan motor and a plurality of fan blades, wherein each one of the fan blades of the plurality of fan blades defines an airfoil profile. Each one of the fan blades of the plurality of fan blades has: (a) a lower surface, wherein the lower surface comprises a concave portion extending between a first point and a second point, wherein the concave portion of the lower surface is defined by a first ellipse, and wherein a maximum thickness of the airfoil profile is defined at the first point along the airfoil profile; (b) an upper surface, wherein the upper surface comprises a convex portion extending between a third point and a fourth point, and wherein the convex portion of the upper surface is defined by a second ellipse; (c) a leading edge, wherein the leading edge is of a substantially convex shape, wherein the leading edge extends between the first point of the lower surface and the third point of the upper surface, and wherein a radius of the substantially convex shape of the leading edge varies from the first point of the lower surface to the third point of the upper surface; and a trailing edge, wherein the trailing edge is of a substantially convex shape, wherein the trailing edge extends between the second point of the lower surface and the fourth point of the upper surface, and wherein a radius of the substantially convex shape of the trailing edge varies from the second point of the lower surface to the fourth point of the upper surface. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    While the specification concludes with claims which particularly point out and distinctly claim this technology, it is believed this technology will be better understood from the following description of certain examples taken in conjunction with the accompanying drawings, in which like reference numerals identify the same elements and in which: 
           [0017]      FIG. 1  depicts a schematic view of an exemplary fan mounted to a ceiling; 
           [0018]      FIG. 2  depicts a cross-sectional view of an exemplary fan blade airfoil; 
           [0019]      FIG. 3  depicts a graphical view of an exemplary curvature profile for an exemplary lower surface of the fan blade airfoil of  FIG. 2  aligned with a portion of a first exemplary ellipse; 
           [0020]      FIG. 4  depicts a graphical view of an exemplary curvature profile for an exemplary upper surface of the fan blade airfoil of  FIG. 2  aligned with a portion of a second exemplary ellipse; 
           [0021]      FIG. 5  depicts a second cross-sectional view of the fan blade airfoil of  FIG. 2  showing the surface lengths of the lower surface and the upper surface. 
       
    
    
       [0022]    The drawings are not intended to be limiting in any way, and it is contemplated that various embodiments of the technology may be carried out in a variety of other ways, including those not necessarily depicted in the drawings. The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present technology, and together with the description serve to explain the principles of the technology; it being understood, however, that this technology is not limited to the precise arrangements shown. 
       DETAILED DESCRIPTION 
       [0023]    The following description of certain examples of the technology should not be used to limit its scope. Other examples, features, aspects, embodiments, and advantages of the technology will become apparent to those skilled in the art from the following description, which is by way of illustration, one of the best modes contemplated for carrying out the technology. As will be realized, the technology described herein is capable of other different and obvious aspects, all without departing from the technology. Accordingly, the drawings and descriptions should be regarded as illustrative in nature and not restrictive. 
         [0024]    I. Exemplary Fan Overview 
         [0025]      FIG. 1  depicts an exemplary fan ( 10 ) having a motor assembly ( 20 ), a hub assembly ( 30 ) coupled to motor assembly ( 20 ), and a plurality of fan blades ( 50 ) coupled to hub assembly ( 30 ). In the present example, fan ( 10 ) (including hub assembly ( 30 ) and fan blades ( 50 )) has a diameter of approximately 8 feet. In other variations, fan ( 10 ) has a diameter between approximately 6 feet, inclusive, and approximately 24 feet, inclusive. Further still, fan ( 10 ) may have any other suitable dimensions, such as 3 feet, inclusive, to 30 feet, inclusive. Except as otherwise described herein, fan ( 10 ) may be constructed and operable in accordance with at least some of the teachings of any of the references that are cited herein; and/or in any other suitable fashion. 
         [0026]    Motor assembly ( 20 ) is operably coupled to hub assembly ( 30 ) such that motor assembly ( 20 ) rotates hub assembly ( 30 ) relative to motor assembly ( 30 ). It should be understood that when fan blades ( 50 ) are coupled to hub assembly ( 30 ), motor assembly ( 20 ) rotates fan blades ( 50 ) with hub assembly ( 30 ). Motor assembly ( 20 ) of the present example comprises a motor ( 22 ) and a frame ( 24 ). Motor ( 22 ) may comprise an AC induction motor having a drive shaft that is coupled to hub assembly ( 30 ), though it should be understood that motor ( 22 ) may alternatively comprise any other suitable type of motor (e.g., a permanent magnet brushless DC motor, a brushed motor, an inside-out motor, etc.). By way of example only, motor assembly ( 20 ) may be constructed in accordance with at least some of the teachings of U.S. Pat. Pub. No. 2009/0208333, entitled “Ceiling Fan System with Brushless Motor,” published Aug. 20, 2009, the disclosure of which is incorporated by reference herein. Furthermore, fan ( 10 ) may include control electronics that are configured in accordance with at least some of the teachings of U.S. Pat. Pub. No. 2010/0278637, entitled “Ceiling Fan with Variable Blade Pitch and Variable Speed Control,” published Nov. 4, 2010, the disclosure of which is incorporated by reference herein. Alternatively, motor assembly ( 20 ) may have any other suitable components, configurations, functionalities, and operability, as will be apparent to those of ordinary skill in the art in view of the teachings herein. 
         [0027]    In the present example, frame ( 24 ) of motor assembly ( 20 ) is coupled to a support ( 12 ) that is adapted to couple fan ( 10 ) to a ceiling or other support structure. By way of example only, support ( 12 ) may be configured in accordance with the teachings of U.S. Pat. Pub. No. 2009/0072108, entitled “Ceiling Fan with Angled Mounting,” published Mar. 19, 2009, and issued Apr. 10, 2012 as U.S. Pat. No. 8,152,453, the disclosure of which is incorporated by reference herein, and/or in any other suitable configuration. In other versions, motor assembly ( 20 ) may be directly coupled to the ceiling or other support structure. Further still, motor assembly ( 20 ) may be remote from hub assembly ( 30 ) and may be coupled via an axle or other component that is operable to transmit rotational movement from motor assembly ( 20 ) to hub assembly ( 30 ). 
         [0028]    Hub assembly ( 30 ) of the present example is rotatably coupled to motor ( 22 ) such that hub assembly ( 30 ) rotates relative to motor ( 22 ). In the present example, hub assembly ( 30 ) includes a central member ( 32 ) and a plurality of fan blade attachment members ( 34 ) extending radially from central member ( 32 ). Fan blade attachment members ( 34 ) are configured to couple to a first end of fan blades ( 50 ) such that rotation of hub assembly ( 30 ) also rotates fan blades ( 50 ). In the present example, fan blades ( 50 ) are coupled to fan blade attachment members ( 34 ) such that fan blades ( 50 ) have an angle of attack of approximately  10  degrees. Of course it should be understood that the angle of attack, a (shown in  FIG. 2 ), may be at other angles as well. For instance, from −20 degrees, inclusive, to +20 degrees, inclusive. Hub assembly ( 30 ) may be further constructed in accordance with at least some of the teachings of U.S. Pat. Pub. No. 2009/0081045, entitled “Aerodynamic Interface Component for Fan Blade,” published Mar. 26, 2009, and issued Apr. 3, 2012 as U.S. Pat. No. 8,147,204; and U.S. Provisional Patent Application. No. 61/590,469, entitled “Fan with Resilient Hub,” filed Jan. 25, 2012, the disclosure of which is incorporated by reference herein. In addition, or in the alternative, hub assembly ( 30 ) may include a retention system that couples each tip of each fan blade ( 50 ) to an attachment point on hub assembly ( 30 ) via a cable running through each fan blade ( 50 ), such as that disclosed in U.S. Pat. Pub. No. 2011/0262278, entitled “Fan Blade Retention System,” published Oct. 27, 2011. Alternatively, the interface of a fan blade and a fan hub may include any other component or components, or may lack any similar structure at all. 
         [0029]    Fan ( 10 ) may be further configured in accordance with at least some of the teachings of the fan systems disclosed in U.S. Pat. Pub. No. 2009/0097975, entitled “Ceiling Fan with Concentric Stationary Tube and Power-Down Features,” published Apr. 16, 2009, and issued Apr. 3, 2012 as U.S. Pat. No. 8,147,182, the disclosure of which is incorporated by reference herein; U.S. Pat. Pub. No. 2009/0162197, entitled “Automatic Control System and Method to Minimize Oscillation in Ceiling Fans,” published Jun. 25, 2009, and issued Feb. 28, 2012 as U.S. Pat. No. 8,123,479, the disclosure of which is incorporated by reference herein; U.S. Pat. Pub. No. 2010/0291858, entitled “Automatic Control System for Ceiling Fan Based on Temperature Differentials,” published Nov. 18, 2010, the disclosure of which is incorporated by reference herein; and U.S. Provisional Patent App. No. 61/165,582, entitled “Fan with Impact Avoidance System Using Infrared,” filed Apr. 1, 2009, the disclosure of which is incorporated by reference herein. Of course still further configurations and/or constructions for fan ( 10 ) will be apparent to one of ordinary skill in the art in view of the teachings herein. 
         [0030]    II. Exemplary Fan Blades 
         [0031]      FIG. 2  depicts a cross-sectional view of a fan blade ( 50 ) showing an exemplary airfoil profile ( 100 ). For scalability purposes, the characteristics of airfoil profile ( 100 ) will be discussed in dimensionless terms as a function of chord length. Of course it should be understood that a characteristic other than chord length may be set at a desired dimension and the chord length and other characteristics may be derived therefrom. 
         [0032]    Airfoil profile ( 100 ) comprises a lower surface ( 110 ), an upper surface ( 140 ), a leading edge ( 170 ), and a trailing edge ( 180 ). Airfoil profile ( 100 ) is further defined by a chord ( 102 ) having a length c. By way of example only, chord ( 102 ) may be in the range of 5.5 inches, inclusive, to 6 inches, inclusive. Of course larger or smaller chords ( 102 ) may be used as well. Airfoil profile ( 100 ) has a maximum thickness ( 104 ) of approximately 0.157 c and is located at approximately 0.724 c as measured from trailing edge ( 180 ). In the present example, maximum thickness ( 104 ) is located at the point on airfoil profile ( 100 ) where the concave lower surface ( 110 ) transitions to the convex leading lower transition portion ( 120 ), as will be described below. Accordingly, airfoil profile ( 100 ) has an aspect ratio of approximately 6.37:1 chord to thickness. A mean camber line ( 106 ) of airfoil profile ( 100 ) comprises an arc defined by a radius of approximately 2.364 c. It should be understood that portions of mean camber line ( 106 ) near leading edge ( 170 ) and/or trailing edge ( 180 ) may deviate from this arc. Leading edge ( 170 ) is defined by a circle having a radius of approximately 0.06 c. Trailing edge ( 180 ) is defined by a circle having a radius of approximately 0.011 c. In versions where c is a small value, such as below 5.5 inches, the radius of the circle defining trailing edge ( 180 ) may have a value greater than 0.011 c. Alternatively, for versions where c is a large value, the radius of the circle defining trailing edge ( 180 ) may have a value of less than 0.011 c. Still other configurations will be apparent to one of ordinary skill in the art in view of the teachings herein. 
         [0033]    In the present example, lower surface ( 110 ) extends from a first point ( 112 ) to a second point ( 114 ) and forms a concave surface. As shown in  FIG. 2 , first point ( 112 ) is located at approximately 0.724 c as measured from trailing edge ( 180 ). Second point ( 114 ) is located at 0.015 c as measured from trailing edge ( 180 ). It should be understood that second point ( 114 ) may be located at other positions as well. For instance, if chord c is a small value, second point ( 114 ) may be located at a position greater than 0.015 c as measured from trailing edge ( 180 ). A leading lower transition portion ( 120 ) extends from leading edge ( 170 ) to first point ( 112 ) to form a smooth continuous convex surface from lower surface ( 110 ) to leading edge ( 170 ). A trailing lower transition portion ( 130 ) extends from second point ( 114 ) to trailing edge ( 180 ) to form a smooth continuous convex surface as well, though this is merely optional. Likewise, upper surface ( 140 ) extends from a third point ( 142 ) to a fourth point ( 144 ) and forms a convex surface. In the present example, third point ( 142 ) is located at 0.776 c as measured from trailing edge ( 180 ). Fourth point ( 144 ) is located at 0.006 c as measured from trailing edge ( 180 ). It should be understood that fourth point ( 144 ) may be located at other positions as well. For instance, if chord c is a small value, fourth point ( 144 ) may be located at a position greater than 0.006 c as measured from trailing edge ( 180 ). A leading upper transition portion ( 150 ) extends from leading edge ( 170 ) to third point ( 142 ) to form a smooth continuous convex surface from upper surface ( 140 ) to leading edge ( 170 ). A trailing upper transition portion ( 160 ) extends from fourth point ( 144 ) to trailing edge ( 180 ) to form a smooth continuous convex surface as well. While the foregoing generally describes a smooth continuous airfoil profile ( 100 ), it should be understood that discrete features may be included at various points of airfoil profile ( 100 ) that disrupt the smoothness or continuous nature of the airfoil profile ( 100 ). For example, a trip or other feature that disturbs the flow of air about airfoil profile ( 100 ) may be included. Alternatively, pitting or other surface features may also be included. 
         [0034]    Referring to  FIG. 3 , lower surface ( 110 ) of airfoil profile ( 100 ) is shown defined by a portion of an exemplary first ellipse ( 200 ). In the example shown, first ellipse ( 200 ) comprises a major axis ( 210 ) having a length of approximately 1.725 c and a minor axis ( 220 ) having a length of approximately 0.5 c. Lower surface ( 110 ) of airfoil profile ( 100 ) is defined by an arcuate segment ( 230 ) of first ellipse ( 200 ) when airfoil profile ( 100 ) is located at a position such that chord ( 102 ) forms an angle ( 212 ) with major axis ( 210 ) of approximately 11 degrees. Of course it should be understood that in some versions, lower surface ( 110 ) may be defined by other arcuate segments of first ellipse ( 200 ). 
         [0035]    Referring to  FIG. 4 , upper surface ( 140 ) of airfoil profile ( 100 ) is shown defined by a portion of an exemplary second ellipse ( 300 ). In the example shown, second ellipse ( 300 ) comprises a major axis ( 310 ) having a length of approximately 1.843 c and a minor axis ( 320 ) having a length of approximately 0.583 c. Upper surface ( 140 ) of airfoil profile ( 100 ) is defined by an arcuate segment ( 330 ) of second ellipse ( 300 ) when airfoil profile ( 100 ) is located at a position such that chord ( 102 ) forms an angle ( 312 ) with major axis ( 312 ) of approximately 17 degrees. Of course it should be understood that in some versions, upper surface ( 140 ) may be defined by other arcuate segments of second ellipse ( 300 ). 
         [0036]    Referring now to  FIG. 5 , the resulting airfoil profile ( 100 ) has a lower surface length ( 190 ) and an upper surface length ( 192 ). Lower surface length ( 190 ) and upper surface length ( 192 ) are respectfully defined by the lower and upper surfaces of airfoil profile ( 100 ) extending from the intersection of airfoil profile ( 100 ) and mean camber line ( 106 ) at leading edge ( 170 ) to the intersection of airfoil profile ( 100 ) and mean camber line ( 106 ) at trailing edge ( 180 ). In the example shown, lower surface length ( 190 ) is approximately 1.033 c and upper surface length is approximately 1.073 c. 
         [0037]    While one merely exemplary airfoil profile ( 100 ) has been described, it should be understood that other airfoil profiles will be apparent to one of ordinary skill in the art in view of the teachings herein. For example, other such airfoil profiles ( 100 ) may be defined by a lower surface ( 110 ) defined, at least in part, by first ellipse ( 200 ) having the equation of x 2 /0.8625 2 +y 2 /0.25 2 =1. In addition to the foregoing, or in the alternative, airfoil profiles ( 100 ) may have an upper surface ( 140 ) defined, at least in part, by second ellipse ( 300 ) having the equation of x 2 /0.9215 2 +y 2 /0.2915 2 =1. 
         [0038]    It should be appreciated that any patent, publication, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated material does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material. 
         [0039]    Having shown and described various embodiments of the present invention, further adaptations of the methods and systems described herein may be accomplished by appropriate modifications by one of ordinary skill in the art without departing from the scope of the present invention. Several of such potential modifications have been mentioned, and others will be apparent to those skilled in the art. For instance, the examples, embodiments, geometries, materials, dimensions, ratios, steps, and the like discussed above are illustrative and are not necessarily required. Accordingly, the scope of the present invention should be considered in terms of the claims and is understood not to be limited to the details of structure and operation shown and described in the specification and drawings.