Abstract:
A body having a fuselage, a wing unit including a main wing, and a propulsion unit including an engine. The wing unit includes a main wing protruding out from the lateral center of the WIG vehicle fuselage, a downward wing which is vertically and downwardly installed on the outer tip of the main wing, and a canard which protrudes out horizontally from the front end of the fuselage, which is in the moving direction of the WIG vehicle from the main wing. The canard includes a horizontal stabilization plate which has a stationary horizontal panel structure, and a variable flap which is installed to face the rear surface of the horizontal stabilization plate. In the lateral cross section shape, the front surface portion including the leading edge is round at a proper thickness to prevent clearance generated by turning of the canard, the trailing edge is sharp and straight, and the thickness of a portion between the thickest portion and rear portion narrows. The lateral cross section of the entire horizontal stabilizer is airfoil-shaped. Accordingly, the invention is able to resolve the design problem of the horizontal stabilizer caused by a ground effect because the WIG vehicle comprises a canard for stabilizing vertical disturbance instead of a horizontal stabilizer.

Description:
CROSS-REFERENCE TO RELAYED ED APPLICATIONS 
       [0001]    This application is the U.S. national phase of the International Patent Application No. PCT/KR20091001354 filed Mar. 18, 2009, which claims the benefit of Korean Application No. 10-2008-0081184 filed Aug. 20, 2008, the entire content of which is incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates, in general, to a wing structure of a Wing-In-Ground effect (WIG) vehicle and, more particularly, to a fuselage of a WIG vehicle and a wing configuration, in which a wing structure of the WIG vehicle is constructed such that it substitutes a horizontal stabilizer with a canard. 
         [0004]    2. Description of the Related Art 
         [0005]    Generally, aircraft and WIG vehicles are equipped with a horizontal stabilizer in order to reduce pitching. The horizontal stabilizer is designed such that it has a proper size and a proper initial angle in consideration of a downwash angle caused by the front main wings. 
         [0006]    The WIG vehicle is subjected to changes in the downward angle not only by an intended change in the shape, such as a change in the flat shape of the main wing, but also by the cruising height. Specifically, the size of the downward angle is small due to the inclination of the stream toward being parallel at a low altitude, whereas the size of the downward angle becomes greater to the original value at a high altitude. 
         [0007]    That is, sometimes it is not easy to produce an appropriate design for the horizontal stabilizer, and when the WIG vehicle is cruising, undesirable instability may occur in some cases. 
         [0008]    However, no devices capable of substituting the horizontal stabilizer have been developed to date. 
       SUMMARY 
       [0009]    Accordingly, the invention has been made keeping in mind the above problems occurring in the prior art, and an embodiment of the invention decreases the amount of severe changes in downwash angle and provides consistent control over the pitching of a fuselage in a WIG vehicle that cruises at a low altitude close to the surface of the water. 
         [0010]    An embodiment of the invention removes design difficulties of a horizontal stabilizer using the ground effect and thus exclude structural addition, which would otherwise be necessary for the installation of the horizontal stabilizer, thereby improving the ease of fabrication and reducing the weight of the fuselage. 
         [0011]    An embodiment of the invention provides a WIG vehicle that excludes a horizontal stabilizer. The WIG vehicle includes a body including a fuselage, a wing structure including a main wing, and a propulsion unit including an engine. The wing structure includes the main wing protruding outward from the central portion of the fuselage of the WIG vehicle; a downward wing bent vertically downward from the distal end of the main wing; and a canard protruding horizontally outward from the front part of the fuselage. The canard is placed ahead of the main wing in the direction in which the WIG vehicle proceeds. The downward wing includes a downward panel bent downward from and integrally fixed to the distal end of the main wing, and a variable rudder part opposing a rear surface of the downward panel. The downward wing including the rudder part has a vertical cross-section that is configured such that the front portion of the downward wing including the leading edge is rounded at a suitable thickness so that flow separation does not occur, and the rear portion of the downward wing has a thickness converging from the portion having a maximum thickness, with the trailing edge of the downward wing sharply converging in a linear shape. The entire downward wing has a vertical cross-sectional shape formed as an airfoil. 
         [0012]    In an embodiment of the invention, the canard may include a horizontal stabilizing plate having a fixed horizontal panel structure and an elevator part provided to oppose the horizontal stabilizing plate. The elevator part has a side cross-sectional shape such that the front portion of the elevator part including the leading edge is rounded with a suitable thickness so that flow separation does not occur, the thickness converging from the portion that has a peak thickness, and the trailing edge of the elevator part is configured such that it converges in a straight shape. The canard has an airfoil-like overall side cross-section. 
         [0013]    In addition, the lower portion of the downward wing may be shaped as an arc or a streamlined “V” in order to decrease friction with the sea water or the air adjacent to the surface of the sea. 
         [0014]    In addition, the downward wing may be made of carbon fiber aluminum. 
         [0015]    Furthermore, a plurality of ribs and a plurality of spars may be provided inside the main wing. The ribs connect the leading edge to the trailing edge of the main wing, and are shaped as an airfoil, and the spars extend across the ribs. 
         [0016]    When the wing structure of the invention is mounted to the WIG vehicle, there are effects capable of decreasing the amount of severe changes in downwash angle and providing consistent control over the pitching of the fuselage in a WIG vehicle that cruises at a low altitude close to the surface of the water. 
         [0017]    In addition, it is possible to improve the ease of fabrication and reduce the weight of the fuselage by excluding the structural addition, which would otherwise be necessary for the installation of the horizontal stabilizer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a side cross-sectional view of a WIG vehicle excluding a horizontal stabilizer; 
           [0019]      FIG. 2  is a first embodiment of a wing structure of the WIG vehicle according to the invention; 
           [0020]      FIG. 3  is a perspective cross-sectional view of the main wing and the downward wing shown in  FIG. 2 ; 
           [0021]      FIG. 4  is an internal perspective view showing the main wing inside which spars and ribs are provided; 
           [0022]      FIG. 5  is an assembled perspective view showing a coupling portion of the downward wing; 
           [0023]      FIG. 6  is a view showing the shape of an embodiment of the lower portion of the downward wing; 
           [0024]      FIG. 7  is a view showing the structure of a downward wing according to another embodiment; and 
           [0025]      FIGS. 8 and 9  are views showing the shape of other embodiments of the lower portion of the downward wing shown in  FIG. 7 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0026]    Hereinafter, the wing structure of a Wing-In-Ground effect (WIG) vehicle according to the invention will be described in detail with reference to the accompanying drawings. 
         [0027]      FIG. 1  is a side cross-sectional view of a WIG vehicle excluding a horizontal stabilizer,  FIG. 2  is a first embodiment of a wing structure of the WIG vehicle according to the invention,  FIG. 3  is a perspective cross-sectional view of the main wing and the downward wing shown in  FIG. 2 ,  FIG. 4  is an internal perspective view showing the main wing inside which spars and ribs are provided,  FIG. 5  is an assembled perspective view showing a coupling portion of the downward wing,  FIG. 6  is a view showing the shape of an embodiment of the lower portion of the downward wing,  FIG. 7  is a view showing the structure of a downward wing according to another embodiment, and  FIGS. 8 and 9  are views showing the shape of other embodiments of the lower portion of the downward wing shown in  FIG. 7 . 
         [0028]    In the following description with reference to the accompanying drawings, the wing structure is provided to be symmetrical on the left and right with respect to the axis of the fuselage of the WIG vehicle. Therefore, it should be understood that, although the structure of one wing is described, the other wing has the same structure. 
         [0029]      FIG. 1  is a side cross-sectional view of a WIG vehicle excluding a horizontal stabilizer. The wing structure will be described first with reference to  FIGS. 2 to 6 . 
         [0030]    As shown in  FIG. 2 , the overall wing structure of a WIG vehicle according to a first embodiment of the invention includes a main wing  200  protruding outward from the central portion of a fuselage  100  of the WIG vehicle, a downward wing  300  bent vertically downward from a respective distal end of the main wing  200  without a seam, and a canard  600  protruding horizontally outward from the front part of the fuselage  100 , placed ahead of the main wing  200  in the direction in which the WIG vehicle proceeds. The downward wing  300  includes a downward panel  310  bent downward from and integrally fixed to the distal end of the main wing  200 , and a variable rudder part  320  opposing the rear surface of the downward panel  310 . In the vertical cross-sectional shape of the downward wing  300  including the rudder part  320 , the front portion including the leading edge  321  is rounded at a suitable thickness such that flow separation does not occur, and the rear portion is configured such that its thickness converges from the portion having the maximum thickness and the trailing edge  329  sharply converges in a linear shape. The vertical cross-sectional shape of the entire downward wing  300  is configured to have the form of an airfoil. 
         [0031]    Specifically, although the downward wing of the related art has a linear panel-like shape with a predetermined thickness in the vertical direction, the structure of the downward wing according to the first embodiment has a streamlined cross-sectional shape such as an airfoil and thereby serves to decrease turbulence and increase thrust. More specifically, below the wing, fluid generally flows from the inside to the outside. In this case, if a distal end plate or the downward wing is vertically arranged at the distal end of the wing, the flow of fluid below the wing has a predetermined angle of approach (i.e., an angle of attack) with respect to the distal end plate. This arrangement generates lift at the distal end plate. The lift can be divided into a component in the direction in which the WIG vehicle proceeds and a component in the horizontal direction. The component in the direction in which the WIG vehicle proceeds serves to increase thrust. Therefore, if the distal end plate has an airfoil cross-section that is a typical cross-section of a wing, the generation of the lift can be maximized. 
         [0032]    In other words, the leading edge of the lifting surface at the distal end is configured such that it has a suitable thickness so that flow separation does not occur, and the trailing edge is sharp such that the lift is maximized when flow separation occurs, thereby serving to decrease resistance due to decreased turbulence and increase thrust. In addition, since the volume of the downward wing having this shape is much greater than that of the distal end plate of the related art, the design is advantageous in absorbing impact when the vehicle takes off and lands on the water and providing stability against rolling. Therefore, the downward wing can substitute a float for WIG vehicles and water planes. Since a water plane is equipped with a float having the form of a ski as an auxiliary landing gear, the downward wing can substitute the float when its cross-sectional shape and lower shape are streamlined as described above, thereby simplifying the structure. 
         [0033]    In the downward wing  300 , the fixed structure of the downward panel  310  and the variable structure of the rudder part  320 , which opposes the downward panel  310 , are intended such that the downward wing  300  can be used to control yawing in the WIG vehicle  100  instead of a vertical stabilizer. In greater detail, when the wing is disposed on the upper portion of the fuselage, the relatively large downward wing  300  is attached to the main wing in order to maximize the ground effect. In this case, the lifting surface phenomenon is employed, and a drive unit  320  such as a rudder of the vertical stabilizer is installed on the rear surface of the lifting surface. The drive unit  320  is operated in order to provide stability against yawing and compensate for the asymmetry of thrust in the lateral direction. 
         [0034]    Here, the downward panel  310  is a stationary type that is connected to and bent vertically downward from the distal end of the main wing  200  without a seam. The rudder part  320  is a variable type, and is mounted to the rear surface of the downward panel  310  in order to maneuver the fuselage to the left or right. 
         [0035]    The canard  600  is provided on the front part of the fuselage  100  of the WIG vehicle ahead of the main wing  200  in the direction in which the WIG vehicle proceeds, such that it protrudes horizontally outward. The canard  600  includes a fixed horizontal stabilizing plate  610  in the front portion thereof, the horizontal stabilizing plate  610  horizontally protruding outwards, and an elevator part  620  fixed to the horizontal stabilizing plate  610  in order to maneuver the fuselage to climb or descend. 
         [0036]    A detailed description will be given below of the structures of the downward wing  300  and the canard  600 . 
         [0037]    First, the main wing  200 , the downward panel  310 , and the horizontal stabilizing plate  610  are configured such that they are fixed when maneuvering the WIG vehicle. The rudder part  320 , which rotates the fuselage  100  to the left and right in response to the operation of the drive unit, and the elevator part  620 , which maneuvers the fuselage to climb or descend in response to the operation of the drive unit, are configured such that they are variable when maneuvering the WIG vehicle. 
         [0038]    That is, the trailing edge  329  of the rudder part  320  is configured to rotate to the left and right, and the trailing edge  629  of the elevator part  620  is configured to rotate up and down in order to provide stability against pitching and compensate for the asymmetry of thrust in the lateral direction. 
         [0039]    In this fashion, the wing structure of the WIG vehicle excluding the vertical stabilizer, which is intended to control pitching, is realized. 
         [0040]    The main wing  200  protrudes outward from the central portion of the side of the WIG vehicle, and is formed as a smooth panels having an airfoil-like side shape that is the same as an airfoil of aircraft of the related art, the panels being sequentially continued, and the interval between the leading edge  201  and the trailing edge  209  decreasing outward. The airfoil shape can be described in greater detail as follows: The lateral shape of the leading edge  201  is horizontally linear, and the upward/downward shape of the leading edge  201  is smoothly rounded. In the section from the leading edge  201  to the trailing edge  209 , the height of the upward/downward streamlined portion of the rounded portion increases across the section from the peak of the leading edge  201  to the position “ 3/10 to 4/10,” and the height of the upward/downward streamlined portion decreases across the section from the position “ 3/10 to 4/10” to the trailing edge  209 , so that the height converges in a sharp shape at the peak of the trailing edge  209 . Here, it is preferred that the main wing  200  have an airfoil-like side shape and be made of carbon fiber aluminum. 
         [0041]    In the downward panel  310 , the leading edge  311  has a smoothly rounded lateral shape, and the trailing edge  319  has a sharp shape so that two separations occur. When the two separations are seen in a plan view, a depression (i.e. a groove)  315  is engraved along a vertical straight line between the separations. 
         [0042]    Here, it is preferred that the downward panel  310  be made of carbon fiber aluminum, and the lower shape have the form of an arc or a streamlined “V” in order to minimize friction with the surface of the water or the ground. 
         [0043]    The rudder part  320  is mounted by being spaced apart a predetermined distance from the depression  315  of the downward panel  310  so that it can move with directivity as a drive unit. In addition, the leading edge  321  is rounded, and the trailing edge  329  is sharply shaped such that one separation occurs. Here, it is preferred that the leading edge be formed as a vertical straight panel having an airfoil-like planar shape and be made of carbon fiber aluminum, and that the trailing edge have the form of an arc or a streamlined “V.” 
         [0044]    In addition, when the trailing edge  329  of the rudder part  320  is rotated to the left and right by operating the drive unit, the rounded portion of the leading edge  321  rotates without creating friction against the depression. 
         [0045]    In addition, the canard  600  includes the horizontal stabilizing plate  610  having the structure of a fixed horizontal panel, and the elevator part  620  provided to oppose the horizontal stabilizing plate  610 . Referring to the side cross-sectional shape of the elevator part  620 , the front portion including the leading edge  621  is rounded with a suitable thickness so that separation does not occur, the thickness converging from the portion that has the peak thickness, and the trailing edge  629  is configured such that it converges in a straight shape. Thereby, the overall side cross-sectional shape of the canard  600  has the form of an airfoil that resembles a tadpole. 
         [0046]    The horizontal stabilizing plate  610  protrudes outward from the front portion of the fuselage  100  ahead of the main wing, and is formed as smooth panels having an airfoil-like side shape that is the same as an airfoil of aircraft of the related art, the smooth panels being sequentially continued, and the interval between the leading edge  611  and the trailing edge  619  decreasing. The upward/downward shape of leading edge  611  is smoothly rounded, and the trailing edge  619  is sharply shaped such that two separations occur. When the two separations are seen in a plan view, a depression (i.e. a groove)  615  is engraved along a vertical straight line between the separations. In addition, it is preferred that the horizontal stabilizing plate  610  be made of carbon fiber aluminum. 
         [0047]    The elevator part  620  is mounted by being spaced apart a predetermined distance from the depression  615  of the horizontal stabilizing plate  610 . Here, the leading edge  621  of the elevator part  620  has a rounded shape, and the trailing edge  629  is sharply shaped such that one separation occurs. In addition, it is preferred that the elevator part have an airfoil-like side shape and be made of carbon fiber aluminum. 
         [0048]    In addition, it is preferred that the elevator part  620  be mounted in a predetermined space such that the rounded portion of the leading edge  621  rotates without creating friction against the depression when the trailing edge  629  of the elevator part  620  is rotated to the left and right by operating the drive unit. 
         [0049]    A more detailed description will be given below of the configuration of the downward wing  300  including the downward panel  310  and the rudder part  320  and of the configuration of the canard  600  including the horizontal stabilizing plate  610  and the elevator part  620 . 
         [0050]    As shown in the figures, in the leading edge  311  of the downward panel  310 , the upward/downward shape is a vertical straight line, and the lateral shape is smoothly rounded. In the longitudinal direction from the leading edge  311  to the trailing edge  329  of the downward wing  300 , the streamlined length of the rounded portion in the lateral direction increases from the peak of the leading edge  311  to the position “ 3/10 to 4/10,” and the streamlined length of the rounded portion in the lateral direction decreases from the position “ 3/10 to 4/10” to the trailing edge  329  of the downward wing. The portion from the trailing edge  319  to the left streamlined end of the downward panel  310  forms a first sharp portion, and the portion from the trailing edge  319  to the right streamlined end of the downward panel  310  forms a second sharp portion. In addition, the depression (i.e. groove)  315  is formed in the space between the first and second sharp portions by being engraved vertically inward. 
         [0051]    Here, the rudder part  320  acts as a rudder in order to maneuver the fuselage  100  to the left and right, has the form of an airfoil, and functions so that it can compensate for the asymmetry of thrust in the lateral direction, which occurs from the left and right ends of the left and right main wings when the drive unit is operated to maneuver the WIG vehicle. 
         [0052]    That is, referring to the airfoil shape, the lateral shape of the leading edge  321  of the rudder part  320  is smoothly rounded. In the longitudinal direction from the leading edge  321  to the trailing edge  329 , the streamlined length of the rounded portion in the lateral direction increases from the peak of the leading edge  321  to the position “ 3/10 to 4/10” along the airfoil shape of the downward wing  300 , and the streamlined length of the rounded portion in the lateral direction decreases from the position “ 3/10 to 4/10” to the trailing edge  329  of the rounded portion, so that the length sharply converges at the peak of the trailing edge  329 . 
         [0053]    In addition, in the horizontal stabilizing plate  610 , the leading edge  611  is a straight line in the lateral direction, and is smoothly rounded in the upward/downward direction. In the section from the leading edge  611  to the trailing edge  629  of the canard  600 , the height of the upward/downward streamlined shape of the rounded portion increases from the peak of the leading edge  611  to the position “ 3/10 to 4/10” and decreases from the position “ 3/10 to 4/10” to the trailing edge of the canard  600 . The portion from the trailing edge  619  to the upper streamlined end of the horizontal stabilizing plate  610  forms a third sharp portion, and the portion from the trailing edge  619  to the lower streamlined end of the horizontal stabilizing plate  610  forms a fourth sharp portion. In addition, the depression (i.e. groove)  615  is formed in the space between the third and fourth sharp portions by being engraved vertically inward. 
         [0054]    Here, the elevator part  620  is constructed to have the form of an airfoil, and is a device that maneuvers the fuselage to climb and descend. 
         [0055]    For this, the airfoil shape can be designed such that the upward/dowmward shape of the leading edge  621  is smoothly rounded. In addition, in the section from the leading edge  621  to the trailing edge  629 , the height of the upward/downward streamlined portion of the rounded portion increases from the peak of the leading edge  621  to the position “ 3/10 to 4/10,” the height of the upward/downward streamlined portion of the rounded portion decreases from the position “ 3/10 to 4/10 ” to the trailing edge  629 , and the height sharply converges at the peak of the trailing edge  629 . 
         [0056]    As described above, the wing structure of the WIG vehicle of the invention is configured such that the wing is mounted symmetrically on the left and right with respect to the reference line of the fuselage  100  of the WIG vehicle. Although the wing structure of the WIG vehicle has been described with respect to one wing, the left and right wings have the same structure as they are symmetric. 
         [0057]    Therefore, the wing structure of the WIG vehicle of the invention minimizes turbulence and induced drag that occur at the distal end of the main wing by maximizing the wing-in-ground effect (or wing-in-surface effect) by excluding the vertical stabilizer and the horizontal stabilizer unlike aircraft. Since the downward wing has a much greater volume than the distal end plate, it can absorb impact that is applied to the fuselage when WIG vehicle takes off and lands and provide stability against the rolling of the fuselage. 
         [0058]      FIGS. 7 to 9  show another embodiment of the invention, in which the downward panel  310  and the rudder part  320  are configured the same as those of the foregoing embodiment but the coupling structure is different from that of the foregoing embodiment. That is, the vertical width of the rudder part  320  is set to be shorter than the vertical width of the downward panel  310 , and the downward panel  310  has a storage recess  317  in the rear surface thereof, the storage recess  317  having a size capable of storing the rudder part  320 . Thereby, the rudder part  320  is mounted inside the storage recess  317  in the rear surface of the downward panel  310 . In the wing structure of the WIG vehicle, the functions of the respective components and the other wing shapes are the same as those of the foregoing embodiment. Therefore, repeated descriptions will be omitted. 
         [0059]      FIGS. 8 and 9  show the structure of the lower portion of the downward wing  300  according to various embodiments of the downward wing structure. 
         [0060]    The figures show the cases in which the shape of the lower portion has the form of a rounded arc, and in which the shape of the lower portion has the form of a streamlined “V.” These shapes are intended to reduce friction with the water surface or the air layer on the water surface when the WIG vehicle is maneuvered, thereby further maximizing lift and thrust effects. In addition, these shapes are merely an illustrative example, but modifications and applications of the wing structure and the coupling structure are not, of course, limited to such shapes. 
         [0061]    While the invention has been shown and described with reference to the certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention. Therefore, the scope of the invention are not limited to the foregoing embodiments, but shall be defined by the appended claims and equivalents thereof. 
         [0062]    As described above, in general, aircraft and WIG vehicles are equipped with a horizontal stabilizer in order to reduce pitching. The horizontal stabilizer is designed such that it has a proper size and a proper initial angle in consideration of a downwash angle caused by the front main wings. The WIG vehicle is subjected to changes in the downward angle not only by an intended change in the shape, such as a change in the flat shape of the main wing, but also by the cruising height. Specifically, the size of the downward angle is small due to the inclination of the stream toward being parallel at a low altitude, whereas the size of the downward angle becomes greater to the original value at a high altitude. That is, sometimes it is not easy to produce an appropriate design for the horizontal stabilizer, and when the WIG vehicle is cruising, undesirable instability may occur in some cases. However, no devices capable of substituting the horizontal stabilizer have been developed to date. The need and demand for the wing structure of the wing ship of the invention, which has been developed by conceiving the foregoing problems, will further increase in response to an increase in demand for wing ships from now on. 
       DESCRIPTION OF REFERENCE CHARACTERS 
       [0063]      100 : fuselage of a WIG vehicle 
         [0064]      200 : main wing 
         [0065]      211 : spar 
         [0066]      212 : rib 
         [0067]      300 : downward wing 
         [0068]      310 : downward panel 
         [0069]      320 : rudder part 
         [0070]      400 : horizontal stabilizer 
         [0071]      410 : horizontal stabilizing plate 
         [0072]      420 : elevator part 
         [0073]      500 : vertical stabilizer 
         [0074]      600 : canard 
         [0075]      610 : horizontal stabilizing plate 
         [0076]      615 : depression 
         [0077]      620 : elevator part