Abstract:
An apparatus for reducing drag on a moving vehicle includes various combinations of a movable segments and a swing arm. Each combination is adapted to be mounted to the rear of the vehicle with a fixed portion being positioned forward of the movable segment upon extraction. The movable segments have a retracted position and an extended position and may be biased to the retracted position. The movable segments deploy to the extended position when moving above a predetermined velocity and returns to a retracted position when moving below the predetermined velocity.

Description:
This application is a continuation-in-part application of U.S. patent application Ser. No. 11/653,536, filed Jan. 16, 2007, and titled “Apparatus for Reducing Drag on Vehicles,” and claims priority from U.S. Provisional Patent Application No. 61/374,418, filed Aug. 17, 2010, and titled “Apparatus for Reducing Drag on a Vehicle.” The disclosures of the above-recited prior applications are each hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     Aspects of this invention relate generally to the field of atmospheric drag reduction, and more particularly to an apparatus for reducing drag on vehicles. 
     2. Background of the Invention 
     When a vehicle is in motion, a low pressure area generally forms at the rear of the vehicle, and the low pressure area may result in increased drag. The increased drag can increase resistance to the motion of the vehicle and force the engine of the vehicle to work harder, and as a result reduce mileage, among other things. The increased drag is often aggravated by the shape of the vehicle. For example, the square-shaped rear end of a semi-tractor trailer may cause far more drag than the round-shaped end of a sports car. 
     There have been a number of drag reducing devices described in the related art. For example, U.S. Pat. No. 5,280,990 to Rinard (“Vehicle Drag Reduction System,” issued on Jan. 25, 1994) describes fixed-position mounted vanes to direct air to the rear of a semi-tractor trailer. Similar devices are found in U.S. Pat. No. 3,999,797 to Kirsch et al. (“Airvane Device for Bluff Vehicles and the Like,” issued on Dec. 28, 1976) and U.S. Pat. No. 3,960,402 to Keck (“Vehicle Flow Direction Vanes,” issued on Jun. 1, 1976). 
     U.S. Patent Application Publication No. US2004/0256885 to Bui (“Rear Spoiler With Motorized Vertical and Angle Adjustability,” published on Dec. 23, 2004), which provides an adjustable rear spoiler that comprises a wing-like mechanism for trucks, has an electric motor actuator for transmitting rotational motion to a worm gear box assembly, and has a wing unit and wing mounting brackets attached to upper linkage supports to create pivotal angle adjustments. 
     U.S. Pat. No. 6,045,095 to Parrish, IV (“Vane-Airfoil Combination,” issued on Apr. 4, 2000) shows a vane-airfoil combination that comprises a rotating set of vanes located in front of the leading edge of the airfoil assembly. WIPO Application No. W092/19485 to Eliahou (“Vehicle Streamlining Device for Pressure Drag Reduction,” published on Nov. 12, 1992) discloses a device for diverting air at the rear of a trailer that comprises a flap for streamlining a vehicle to reduce drag. The flap is raised or lowered by an actuator connected to the vehicle speedometer. U.S. Pat. No. 1,714,609 to Massey (“Airplane,” issued on May 25, 1928) shows a dual airfoil for vehicles that comprises a pair of airfoils that provide lift and have forward and rear positions. U.S. Pat. No. 1,913,169 to Martin (“Wing and Like Member for Aircraft,” issued on Jun. 6, 1933) provides a combination triple airfoil for vehicles that comprises three airfoils that provide lift and reduce drag and have staggered positions relative to one another. 
     U.S. Pat. No. 4,810,022 to Takagi et al. (“Automotive Vehicle With Adjustable Aerodynamic Accessory and Control Therefor,” issued on Mar. 7, 1989) discloses an adjustable aerodynamic spoiler with a controller that has spoiler settings regulated automatically by sensed driving conditions, such as vehicle speed, crosswinds and the like. 
     SUMMARY 
     There remains an unmet need to more effectively reduce the drag caused by the low pressure area that is created behind a moving vehicle. Aspects of the present invention provide an apparatus for reducing drag on vehicles via features that may be wind-actuated or otherwise mechanically actuated. Another variation in accordance with aspects of the current invention may include a foil disposed in a retracted position that may deploy in an expanded position during motion of the vehicle on which the foil is disposed. According to various exemplary aspects, the foil may be activated by a swing arm, and the foil may deploy in several segments from a retracted position to a fully expanded position. 
     Other aspects and advantages will become apparent in the following description and the features of novelty which illustrate exemplary aspects of this invention will be pointed out with particularity. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various exemplary aspects of the systems and methods in accordance with aspects of this invention will be described in detail, with reference to the following figures, wherein: 
       FIGS.  1 (A)-(B) are perspective views of an apparatus for drag reduction in a retracted position and an expanded position, according to various aspects of the present invention; 
       FIGS.  2 (A)-(B) are perspective views of an apparatus for drag reduction, according to various aspects of the present invention, in both a retracted position and an expanded position; 
         FIG. 3  is a perspective view of a swing arm that moves the drag reducing apparatus between a retracted and an expanded position, according to various aspects of the current invention; 
         FIG. 4  is a perspective view of a drag reducing apparatus during deployment between a retracted position and an expanded position, according to various aspects of the current invention; 
       FIGS.  5 (A)-(B) show representative views of another exemplary drag reducing apparatus, according to various aspects of the present invention, in both a retracted position and an expanded position; 
         FIGS. 6A-6B  is a perspective view of another exemplary drag reducing apparatus, according to various aspects of the present invention; 
         FIG. 7  is a perspective view of another exemplary drag reducing apparatus, according to various aspects of the present invention; 
       FIGS.  8 (A)-(B) show views of an exemplary swing arm used in a drag reducing apparatus, according to various aspects of the present invention; and 
       FIGS.  9 (A)-(B) are illustrations of torsion hinge-pins attaching air diverters according to various aspects of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     These and other features and advantages in accordance with aspects of this invention are described in, or will be apparent from, the following detailed description of various exemplary implementations. 
     FIGS.  1 (A)-(B) are perspective views of an apparatus for drag reduction  100 , according to various aspects of the present invention, shown in a retracted position and an expanded position, respectively. In  FIG. 1(A) , a sectioned thin profile wind diverting material  110  (each wind diverting material also interchangeably referred to herein as a “foil”) is held in a retracted position. According to various aspects, the sectioned foil  110  is held in the retracted position under the pressure of one or more biasing features, such as springs (see, e.g., FIG.  8 (A)), or torsion pins (see, e.g.,  FIG. 9 ) that bias diverters towards a retracted position. A portion  105  of the sectioned foil  110  may be fixed to a portion of a vehicle  120 , such as a side or a rear portion, in order to fix the foil  110  to the vehicle  120 . It should be noted that the sectioned foil  110  may be held in the retracted position because the vehicle  120  is either not moving or moving below a predetermined speed, with or without biasing. A more detailed description of an exemplary structure of the segmented foil  110  is given below with reference to  FIG. 4 . 
     According to various aspects, another portion  115  of the sectioned foil  110 , opposite the portion  105 , may be proximally joined to a portion of the vehicle  120 , such as the back portion  125 , via a swing arm  130 . The swing arm  130  may be connected to the back portion  125  at a swing arm attachment portion  135 , which may also operate as a stop, for example, in order to fix the swing arm  130  to the vehicle  120 . An exemplary swing arm  130  will be described in greater detail below with reference to FIGS.  8 (A)-(B). 
     In  FIG. 1(B) , the foil  110  is shown as fully expanded, and the segments  50 ,  52  and  54  are deployed, as a result of the expansion of the foil  110 . It should be noted that although three segments are represented in FIGS.  1 (A)-(B), other variations of the current invention may include more or less segments. When fully expanded, the foil  110  is kept in an advantageous drag reducing position via the swing arm  130 . In  FIG. 1(B) , the advantageous drag reducing position is a position somewhat angled or curved in an inward curve relative to perpendicular to the surface of the back portion  125  of the vehicle  120 , so as to follow generally the fluid flow of air past the rear of the vehicle. However, according to various aspects of the current invention, other advantageous drag reducing positions may be determined. The attachment portion  135  of the swing arm  130  may serve as the attachment point of the swing arm  130  to the back portion  125  of the vehicle  120 , and may also serve as a stop to prevent the swing arm  130  from over-rotating relative to the side of the vehicle  120  to which the portion  105  is attached. According to various aspects, the portion  135  may also comprise a biasing element, such as a spring or a torsion pin, to bias the swing arm to a retracted position. 
     FIGS.  2 (A)-(B) show perspective views of an exemplary segmented foil  110 , according to various aspects of the present invention, in both a retracted position and an expanded position, respectively. In  FIG. 2(A) , the swing arm  130  is disposed in a resting position against the back surface  125  of the vehicle  120 , in a generally parallel position relative to the surface  125 . The segments  50 ,  52  and  54  of the foil  110  are disposed adjacent each other in this retracted position, adjacent the side of the rear portion of the vehicle  120 . It should be noted that, although the foil  110  is described as being retracted on the side of the vehicle  120 , other aspects of the invention may include the foil  110  being retracted on the top portion of the vehicle  120 . According to one variation in which the foil is located on the top of the vehicle  120 , the expanded position of the foil  110  may include the foil expanding downward from the top of the vehicle  120 . 
     In  FIG. 2(B) , the deployed foil  110  may include segments with a plurality of colors and/or materials, for example. For example, the segments  50 ,  52  and  54  may not necessarily be manufactured from the same material or have the same overall aspect, such as color, shape, and size. According to various aspects of the invention, one or more of the segments  50 ,  52  and  54  may include pores, perforations, or other air flow affecting features and/or shape related variations. 
       FIG. 3  is a perspective view of the swing arm  130  that moves the segmented foil  110  between a retracted position and an expanded position, according to various aspects of the current invention. It should be noted that, although the swing arm  130  is illustrated as being located at the bottom of the back portion of the vehicle  120  in  FIG. 3 , the swing arm  130  may be located at any other suitable location on the surface  125  of the vehicle  120 , including on top of the vehicle  120  when the foil  110  is located on the top back portion of the vehicle  120 . The attachment portion  135 , which can also serve as a stop when extended, may maintain the swing arm  130  approximately in an optimal position, which may be somewhat angled or curved relative to the surface  125  of the back of the vehicle so as to generally follow the fluid flow of air past the rear of the vehicle in the exemplary aspect illustrated in  FIG. 3 . According to various aspects, the portion  135  may also include a biasing element, such as a spring or a torsion pin, incorporated so as to bias the swing arm  130  to a retracted position. 
       FIG. 4  is a perspective view of an exemplary segmented foil  110  during deployment, in a semi-deployed position between the retracted position and the expanded position, according to various aspects of the current invention. In the exemplary variation, illustrated in  FIG. 4 , the segmented foil  110  includes three segments  50 ,  52  and  54  that extend from the top of the vehicle. It should be noted that although the three segments  50 ,  52 ,  54  are illustrated in  FIG. 4 , the foil  110  may have more or less than three segments. In a retracted position, similar to the position illustrated in  FIG. 1(A)  above, the segments  50 ,  52  and  54  may be adjacent (e.g., stacked atop each other), generally above of the fixed portion  105 . In the foil  110 , segment  50  may be attached to the fixed portion  105 , segment  52  may be attached to segment  50 , and segment  54  may be attached to segment  52 . It should be noted that segment  50  may also be attached to the top of the vehicle via hinges similar to hinges  80 . According to various exemplary aspects of the current invention, as illustrated in  FIG. 4 , segment  50  may be connected to segment  52  via a first hinge or other pivoting or sliding feature  56 , so as to allow relative positioning (interchangeably referred to herein as a “hinge” portion). The hinge  56  may extend between a pivot point  58 , located on or near a portion of the segment  50 , and a pivot  60 , fixed on or near the front of the next segment  52 , for example. In one variation, the hinge portion  56  may include a flat body portion linking segments  50  and  52  at the respective pivot points  58  and  60 . It should be noted that the first hinge portion  56  may, for example, be located at about the midpoint of the segment  50 , as shown in  FIG. 4 . 
     According to various exemplary aspects of the current invention illustrated in  FIG. 4 , segment  50  may also be connected to segment  52  via a second hinge portion  62 . The second hinge portion  62  may extend between a pivot point  64 , located on or near a portion of segment  50 , and a pivot point  66 , located on or near a portion of segment  52 . It should be noted that the pivot point  66  may be located at about a midpoint of the segment  52 , and the pivot point  64  may be located at a rear portion of segment  50 . In one variation, the hinge portion  62  may include a flat portion linking segments  50  and  52  at the respective pivot points  64  and  66 . As a result, during deployment of the foil  110 , as the segments  50  and  52  expand, the hinge portions  56  and  62  also pivotally deploy to form a quadrangularly cross-sectionally shaped volume delimited by both hinge portions  56  and  62  along two opposite sides, and segment  50  and segment  52  along two opposing sides. 
     According to various exemplary aspects of the current invention, segment  52  may be connected to segment  54  via a third hinge portion  68 . The hinge portion  68  may extend between a pivot point  70 , located on or near a portion of the segment  52 , and a pivot point  72 , located on or near a portion of segment  54 . It should be noted that pivot point  70  may be located at about a midpoint portion of the segment  52 , and pivot point  72  may be fixed on or near a front portion of segment  54 , for example. In one variation, the hinge portion  68  may include a flat portion linking both segments  52  and  54  at the respective pivot points  70  and  72 . It should be note that the third hinge portion  68  may be located at about a midpoint of segment  52 . 
     According to various exemplary aspects of the current invention, segment  52  may also be connected to segment  54  via a fourth hinge portion  74 . The fourth hinge portion  74  may extend between a pivot point  76 , located on or near a portion of the segment  52 , and a pivot point  78 , fixed on or near a portion of segment  54 . It should be noted that the pivot point  78  may be located at about a midpoint of segment  54 , and pivot point  76  may be located at a rear portion of segment  52 , for example. In one variation, the hinge portion  74  may include a flat portion linking both segments  52  and  54  at the respective pivot points  76  and  78 . As a result, during deployment of the foil  110 , as the segments  52  and  54  expand, the hinge portions  68  and  74  also deploy and form a quadrangularly cross-sectionally shaped volume delimited by the hinge portions  68  and  74  at opposing sides, and segment  52  and segment  54  at opposite sides. 
     According to various exemplary aspects of the current invention, segment  50  may be connected to the fixed portion  105  of the segmented foil  110  via hinge portion  80 , the hinge portions  80  extending from a pivot point  82  located on or near the segment  50  to fixed portions  105  located on a surface of the vehicle. As discussed above, it should be noted that segment  50  may also be attached to the top of the vehicle via hinges similar to hinges  80 . Alternatively, the hinges  80  may also be attached to a leading edge  84  of the segment  50  instead of a middle portion of the segment  50  as illustrated is  FIG. 4 . For example, a pair of hinge portions  80  may connect the segment  50  at the pivot point  82  to the fixed portions  105 . The fixed portion  105  may be located at a rear portion of the vehicle, for example. According to various aspects, the pivot  82  may be located at about a midpoint of the segment  50 , and may be located on or near the opposite surface of the segment  50  to which the hinge portions  56  is fixed. It should be noted that some or all of the pivot points  58 ,  60 ,  64 ,  66 ,  70 ,  72 ,  76 ,  78  and  82  may include biasing features, such as spring tensioning or other suitable urging mechanisms or features. As a result, each of the segments  50 ,  52  and  54  may be biased to a retracted position. According to various aspects of the current invention, the segments  50 ,  52 ,  54  may be variably biased so that, for example, segment  50  may have a stronger bias to the retracted position than segment  52 , and segment  52  may have a stronger bias to the retracted position than segment  54 . Thus for example, outer extended portion segments may have weaker biases to the retracted position than inner segments. As a result, the outer segments deploy more easily to the expanded position during movement of the vehicle, and the segments less and less easily in a sequential manner as they are located closer to the fixed portion  105 . 
     According to various aspects of the current invention, as shown in  FIGS. 1-4 , when the vehicle  120  is in motion and the foil  110  deploys to its fully expanded and/or optimal position, one or more of the segments  50 ,  52  and  54  may be deployed in a position that is somewhat angled or curved in an inward curve relative to a side of the vehicle  120 , so as to follow generally the fluid flow of air past the rear of the vehicle when the foil  110  is positioned to the side of the vehicle  120 , or on the top of the vehicle  120 . Contemporaneously, at least a portion of one or more of the segments that are further extended from the vehicle  120 , such as segment  54 , may be oriented in a position that is substantially perpendicular to the back surface of the vehicle, such as the surface  125  illustrated in  FIG. 1(B) . 
     According to various aspects, because of the retracted position of the foil  110  and the manner in which the segments  50 ,  52  and  54  are stacked over each other, during expansion of the foil  110  when the vehicle  120  is moving, the pivot portions  56 ,  62 ,  68  and  74  may rotate approximately 180° from their original retracted position to their final expanded position. During deployment of the foil  110 , the segments  50 ,  52  and  54  are connected to one another in a way that forms generally quadrilaterally cross-sectionally shaped volumes, as shown in the perspective view of  FIG. 4  and discussed above (the segments and hinge portions together interchangeably referred to herein as “four-bar” systems). 
     According to various exemplary aspects of the current invention, in an air velocity deployment mode, when the vehicle  120  reaches a predetermined driving speed, airflow may begin to lift (e.g., as an air foil) the segments  50 ,  52  and  54  of the segmented foil  110  away from the fixed portion  105 . As this lift occurs, the segments  50 ,  52  and  54  deploy, and pivot portions  56 ,  62 ,  68  and  74  may rotate relative to the attached sides or top of the vehicle  120 , and stabilize in an optimal or otherwise advantageous drag-reducing position. In that position, the shape of the deployed segmented foil  110  directs air flow to the rear of vehicle  120  in a manner that achieves drag reduction. 
     According to various exemplary aspects of the current invention, a swing arm  130  may be provided to stabilize the segmented foil  110  in an approximately optimal or otherwise advantageous position, such position being the position that allows maximum or increased drag reduction. According to various aspects, this position may be a position where the swing arm  130  is approximately perpendicular to the surface  125  of the back portion of the vehicle  120 . In order to help stabilize the swing arm  130  into such advantageous position, the attachment point  135  may be located at the juncture between the swing arm  130  and the back of the vehicle  120  and may act as a stop, as explained above and shown in more detail in  FIG. 3 . 
     According to various exemplary aspects of the current invention, after deployment of the foil  110 , once the speed of the vehicle decreases below a predetermined speed, the foil  110  may retract automatically under the force of biasing elements in the pivots and among the segments, segments as discussed above. In some variations, if the swing arm  130  is lockable in the optimal position, then the swing arm  130  may be subsequently unlocked by an operator so as to allow the foil  110  to return to the retracted position. The attachment point  135  may also include a stop feature configured to unlock the foil  110  under a shock, such as when the vehicle  120  contacts a wall, another vehicle or another structure. Operation and features of the stop are explained in more detailed below. It should also be noted that the foil  110  may be configured to be deployed and retracted via mechanical or other manual control regardless of the speed of the vehicle. 
     FIGS.  5 (A)-(B)show representative side views of another variation of an exemplary drag reducing apparatus or foil  210 , according to various aspects of the present invention, in both a retracted position ( FIG. 15A ) and an expanded position ( FIG. 15B ). In  FIG. 5(B) , the foil  210  is fixed to either the top, or a side of the vehicle  220 . In  FIG. 5(B) , since the foil  210  is in the retracted position, each one of the segments A, B, C and D are collapsed so as to be adjacent one another. Upon deployment into the expanded position, as shown in  FIG. 5A  whether via mechanical operation or automatically as a traction of movement of the vehicle, each one of the segments A, B and C rotate from their respective retracted positions to their expanded positions, while segment D remains fixed to the surface of the vehicle  220 . For example, segment D remains attached to the side or to the top of the vehicle  220 , while segment C rotates 180° about pivot location P 1 , as illustrated in FIGS.  5 (A)-(B). During the rotation of segment C, segment B remains quasi-parallel to the surface of the vehicle  220  during rotation of segment C. When segment C rotates more completely, as illustrated in  FIG. 5(A) , segment B eventually extends behind the rear side E of the vehicle  220 . It should be noted that, regardless of whether the foil  210  is located on the side of the vehicle or on top of the vehicle, the segment B may extend past the rear side E. During the rotation of segment C and the motion of segment B during extension, segment A may rotate up to about 180° about pivot location P 2  upon the foil  210  being fully expanded. Thus, when the foil  210  is fully extended, segment D remains attached to the surface of the vehicle  220 , segment C has rotated about 180° so as to reach a position approximately parallel to side or to the top of the vehicle  220 , segment B has moved while remaining quasi parallel to the side or to the top of the vehicle  220  before extending inwards toward the rear surface E of the vehicle  220  relative to the side/top, and segment A has rotated about 180°. According to various aspects of the current invention, segments B and D may form an angled- curved- like cross-sectional shape, so as to generally follow the fluid flow of air past the rear of the vehicle  220 , with such a shape and position corresponding to an enhanced drag-reducing position. 
     According to various exemplary aspects of the current invention, in an air velocity deployment mode, when the moving vehicle reaches a predetermined driving speed, airflow may begin to lift the segments A, B and C away from the fixed segment D. As this occurs, the segments A, B and C deploy by rotating relative to each other, as illustrated in  FIG. 5(A) , and stabilize in an optimal or otherwise advantageous drag-reducing position. In the extended position, the shape of the deployed segments directs air flow to the rear of the moving vehicle in a manner that achieves drag reduction. According to various exemplary aspects of the current invention, similar to as shown in  FIGS. 1-3 , a swing arm may be provided to stabilize the deployed segments A, B, C in the deployed position so as to increase drag reduction. 
     According to various exemplary aspects of the current invention, when the speed of the vehicle decreases to below a predetermined speed, the segments A, B and C may retract automatically under the action of biasing features in, for example, pivots P 1  and/or P 2 , which may include torsion pins or biased hinge pins. The pivots P 1  and/or P 2  may be biased to a retracted position via the torsion pins, for example, as illustrated and described more clearly with respect to FIGS.  9 (A)-(B) below. It should also be noted that the segments A, B and C may be deployed and retracted via mechanical or other manual control, regardless of the speed of the vehicle. 
       FIG. 6A  shows a perspective view of another exemplary drag reducing apparatus  310 , according to various aspects of the present invention. In  FIG. 6A , the apparatus  310  includes air diverters  330  that are disposed along the top surface of the vehicle  320 . It should be noted that the air diverters  330  can also be disposed along one or both sides of the vehicle  320 , together with, or alternatively to, being located on top  320  of the vehicle. The air diverters  330  may be disposed in an angled orientation, as shown, and may be disposed substantially along the entire length of the top of the vehicle. The air diverters  330  may also be separated from one another by equal spacing, or by unequal spacing. A side view of an air diverter  330 , as illustrated in  FIG. 6B , reveals that an exemplary such diverter  330  has a thickness and may be fixed to the top of the vehicle  320 , or to the side of the vehicle  320 , via any adhesive substance, adhesive system, or other temporary or permanent affixing material or device such as, an adhesive tape, glue, or the like. Although  FIG. 6A  shows the air diverters  330  as having an angled overall shape, the diverters  330  may have other shapes, such as a stair-step, a straight line, a curved pair, or the like. Because of the shape, size and location of the air diverters  330 , any drag that occurs as a result of the movement of the vehicle  320  may be reduced by producing turbulent breaks in the airflow. In addition, although  FIG. 6B  shows an aspect of the diverter  330  that has an elongated shape with a shaped upper surface, the diverter  330  may have a differently shaped upper surface, such as a flat surface, a rough surface, a stepped surface, a ridged surface, and the like. It should be noted that the air diverters  300  may be used in conjunction with the diverters illustrated in  FIGS. 1 ,  4  and  5 , so that the air flow being directed by the air diverters  300  and towards the side can then be further directed by the diverters as illustrated in any of  FIGS. 1 ,  4  and  5 . 
       FIG. 7  is a perspective view of representative portions of another exemplary drag reducing device, according to various aspects of the present invention. In  FIG. 7 , the drag reducing foil  410  is illustrated during its full deployment, attached to either the top of the vehicle or the side of the vehicle  420 . In  FIG. 7 , the foils  410   a ,  410   b ,  410   c ,  410   d  are shown in an extended position and have a flap  450  attached to the outermost foil  410   d . The outermost foil  410   d  is also attached to a back edge  425  of the truck via the swing arm  430 . According to various exemplary aspects, the flap  450  includes one or more perforations  440  of varying sizes. The perforations  440  may increase the performance of the foil  410  by reducing the drag created during motion of the vehicle  420 . 
     FIGS.  8 (A)-(B) show views of certain features of an exemplary swing arm  130  usable with various drag reducing apparatuses, according to aspects of the present invention. In  FIG. 8(A) , the swing arm  130  includes a portion  138  that may attach to an air diverter, and a portion  135  that may be used to secure the swing arm  130  to a bracket  140  of the vehicle. The portion  138  together with the attachment portion may also operate as a stop when the foil to which the swing arm  130  is attached is expanded in its optimal drag reducing position. The portion  135  may have a biasing device, such as a spring coil therewith, used to bias the swing arm  130  towards a collapsed position, such as against the side or top surface of the vehicle in the retracted position of the drag reducing foil. A collapsed position of the swing arm  130  may be a position where the swing arm is inserted in the notch  142  of the bracket  140 . When the swing arm  130  is inserted in the notch  142 , the biasing device  137 , such as a spring, applies a biasing pressure to maintain the swing arm  130  in the notch  142 , thereby locking the swing arm in a fully retracted position. It should be noted that, according to various aspects of the current invention, the swing arm  130  may alternatively be biased towards a position corresponding to a full expansion of the drag reducing device, which may be a position somewhat angled or curved relative to perpendicular to the surface of the back of the vehicle, so as to follow generally the fluid flow of air past the rear of the vehicle. Such a full extension position may correspond to the swing arm  130  being inserted into the notch  144  of the bracket  140 . In this position, the biasing device  137  also applied pressure on the swing arm to remain in the notch  144 , thereby locking the swing arm in a fully extended position. It should be noted that an angle between the positions of the notches  142  and  144  may be lower than 90°. Alternatively, the angle between the notches  142  and  144  may be about 90°. According to various aspects of the current invention, along the longest portion of the exemplary swing arm  130  shown in  FIG. 8(A) , a slide arm  132  is disposed, and the slide arm  132  is configured to slide inside a housing  134 . The housing  134  may include a biasing reduction  136 , such as a spring, to bias the slide arm  132  as it slides inside the housing  134  (e.g., biased to a contracted portion such as to aid in overall biasing of the foil in the collapsed position). 
     According to various aspects of the exemplary swing arm  130  of  FIG. 8(A) , on an end of the housing  134  that is further from the securing portion  135 , a variably extendable cap  133  may be disposed, to allow for the adjustment of the length of the long portion of the swing arm  130 . Accordingly, the length of the swing arm  130  may be adjusted to allow attachment of the drag reducing device when the device is in deployment to reduce drag. The cap  133  may, for example, be threadably engaged with corresponding threads of the housing  134 , so as to allow travel of the cap  133  to longer or overall shorter lengths in conjunction with the housing  134 . On an end of the slide arm  132  that is opposite the securing portion  135 , the swing arm  130  may be attached to a drag reducing foil, for example. Accordingly, the drag reducing foil can be urged by the swing arm  130  to deploy, to retract, or be maintained at an optimal drag-reducing position. At an opposite side to the side attached to the attachment portion  135 , the swing arm  130  may attach to a segment of a drag-reducing foil via attachment portion  137 .  FIG. 8(B)  illustrates an exemplary security portion  135  for the swing arm  130 , according to various aspects of the current invention. 
     Although  FIG. 8(A)  illustrates a swing arm having a rigid elbow  139 , the elbow  139  may include a pivot point that allows the swing arm to collapse or expand slightly a the pivot point  139  and thus rotate about the attachment portion  135 , as indicated by the arrows on  FIG. 8(A) . It should also be noted that this rotation feature of the elbow  139  may be part of a swing arm that does not include a slide portion  134  and an urging portion  136 . In other words, the swing arm may have a long side that is rigid, similarly to the swing arm  130  illustrated in  FIG. 3 , and a pivot point  139  that allows the swing arm to rotate about the attachment portion  135  in order to accommodate any movement of the air diverters between a retracted position and an extended position. 
     FIGS.  9 (A)-(B) contain representative illustrations of various features of exemplary torsion hinge-pin attaching air diverters, according to various aspects of the present invention. In  FIG. 9B , the air diverter or foil  500  is fixed to the top (or side)  520 , (or  550 ) of a vehicle.  FIG. 9(A)  illustrates several segments  510 ,  530  and  540  of the foil  500  attached to one another via hinge-pins or torsion pins  560 . According to various aspects of the current invention, the hinge-pins or torsion pins  560  are biased so as to bias the foil  500  to a retracted position, where the segments  510 ,  530  and  540  are urged to collapse in a configuration where the segments  510 ,  530 ,  540  are substantially parallel to one another, as the biasing force generally indicated by the direction of the arrows on  FIG. 9(A) . In  FIG. 9(B) , the segments  510 ,  530  and  540  are shown in the retracted position, collapsed in a configuration where the segments are substantially parallel to one another. Upon deployment into the expanded position, whether via mechanical features or during movement of the vehicle, for example, each of the segments  510  and  530  move from their respective retracted positions to their expanded positions against the biasing direction of the hinge-pins  560 , while segment  540  remains fixed to the surface of the vehicle  520  or  550 . According to various aspects, deployment of the segments  510 ,  530  and  540  is accomplished similarly to as described above with respect to  FIGS. 1-5 . 
     While aspects of this invention have been described in conjunction with the exemplary variations outlined above, various alternatives, modifications, variations, improvements, and/or substantial equivalents, thereof whether known or that are or may be presently unforeseen, may become apparent to those having at least ordinary skill in the art. Accordingly, the exemplary aspects of the invention, as set forth above, are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope hereof. Therefore, aspects of the invention are intended to embrace all known or later-developed alternatives, modifications, variations, improvements, and/or substantial equivalents.