Abstract:
An open area platform for supplementing operation of a wind tunnel balance, comprises a platform body and platform adapters. The platform adapter members have first ends and second ends. The first ends are configured to contact the platform body and the second ends are designed to be operatively coupled with the wind tunnel&#39;s balance. As a result, any load on the platform body is configured to be transmitted through the platform adapter members and measured by the wind tunnel balance. Methods of using the open area platform, including for the testing of athletes and their equipment, are also disclosed.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 61/757,628, filed Jan. 28, 2013, which is hereby incorporated by reference. 
     
    
     FIELD 
       [0002]    Wind tunnel testing is now a well-known method for evaluating aerodynamic drag and forces on objects, including aircraft, motor vehicles, buildings and, more recently, individuals and their equipment as configured for competing in timed sporting events (such as cycling, skating and skiing, to name just a few examples). Established wind tunnel fixtures are adequate, but do not present enough flexibility, such as to allow individuals to try different positions in real time testing as well as to allow for the testing of groups of multiple individuals (such as cycling or skating formations). 
       SUMMARY 
       [0003]    Described herein are implementations of a new open area platform and methods for adapting a conventional wind tunnel arrangement to address some of its shortcomings. 
         [0004]    According to a first implementation, an open area platform for supplementing operation of a wind tunnel balance comprises a platform body coupleable to wind tunnel&#39;s balance. In one implementation, there are platform adapter members having first ends and second ends, with the first ends being configured to contact the platform body and the second ends being operatively coupled with the wind tunnel balance. As a result, any load on the platform body is configured to be transmitted through the platform adapter members and measured by the wind tunnel balance. 
         [0005]    The platform adapter members can be configured to position the platform body at a height spaced above a wind tunnel balance work surface. The second ends of the platform adapter members can be designed to extend through openings in a wind balance work surface to connect to the wind tunnel balance. 
         [0006]    In one implementation, there are at least two platform adapter members. In another implementation, there are at least four platform adapter members. 
         [0007]    The open area platform can comprise platform adapter member mounts attached to a side of the platform body that is configured to face the wind tunnel balance. The platform adapter member mounts can comprise base flanges attached to a lower side of the platform body with flanges. The platform adapter members can comprise tubular members that are threadedly connectible to the base flanges. 
         [0008]    The open area platform can comprise an upper surface, a lower surface, and a forward surface extending between the upper and lower surface and configured to face a moving air stream in the wind tunnel. The wind tunnel balance can be calibrated to zero out drag produced by the open area platform. 
         [0009]    In one implementation, the open area platform can define an open area sufficiently large to support at least one skier. In another implementation, the open area platform can define an open area sufficiently large to support at least three bicycles arranged in a riding formation. 
         [0010]    In one implementation, the open area platform provides a support area for supporting wind tunnel test subjects without being mechanically restrained to the platform. 
         [0011]    In one implementation, the forward surface is curved. In one implementation, the upper surface and the lower surface are smooth. 
         [0012]    In one implementation, the platform has a pair of opposing curved end surfaces and a pair of generally straight opposing side surfaces extending between the curved end surfaces. 
         [0013]    According to a method implementation, a method of measuring drag on an athlete in a wind tunnel comprises providing a platform defining an open area sufficient to accommodate the athlete and the athlete&#39;s equipment, coupling the platform to the wind tunnel&#39;s balance, generating an air flow past within the tunnel and directed toward the athlete and the athlete&#39;s equipment and measuring the load exerted on the platform by the athlete, the athlete&#39;s equipment under the action of the air flow. 
         [0014]    The method can include calculating a baseline drag of the platform and subtracting the baseline drag from the load exerted by the platform, the athlete, the athlete&#39;s equipment and the action of the air flow. 
         [0015]    The method can include measuring the load for multiple different positions of the athlete. 
         [0016]    The method can include measuring the load in real time while the athlete and the athlete&#39;s equipment move through a sequence of different positions in real time. 
         [0017]    These and other implementations are described below with reference to the following drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIGS. 1 and 2  are side elevation and end elevation views of a conventional wind tunnel balance having a work surface and illustrating a bicycle supported on the work surface. 
           [0019]      FIG. 3  is a side elevation view of a part of a wind tunnel balance having a new platform according to one implementation mounted above the work surface. 
           [0020]      FIG. 4  is an end elevation view of the wind tunnel balance and new platform of  FIG. 3 . 
           [0021]      FIG. 5  is an exploded perspective view of the new platform, the work surface and the wind tunnel balance. 
           [0022]      FIG. 6  is a side elevation view of a skier emulating a skiing position while he is supported on the new platform, which is in turn supported on the work surface. 
       
    
    
     DESCRIPTION 
       [0023]    Referring to  FIGS. 1 and 2 , a conventional wind tunnel balance  10  is shown with a bicycle B mounted for testing in a wind tunnel. The bicycle B is supported above a wind tunnel balance work surface  16  by a pair of front wheel supports  12  and a pair of rear wheel supports  14 . The front wheel supports  12  are coupled to the bicycle&#39;s front wheel axle in the area of the front fork ends. The rear wheel supports  14  are coupled to the bicycle&#39;s rear wheel axle in the area of the rear dropouts. The supports  12 ,  14  extend through openings in the surface  16  to connect to the wind tunnel balance  10 . 
         [0024]    The wind tunnel balance measures aerodynamic drag through forces transmitted to the balance from an air stream in the tunnel such as one directed from right to left in  FIG. 1  that impinges on the bicycle, which is in turn transmitted through the supports  12 ,  14  to the balance. Drag produced by the supports  12 ,  14 , the wind tunnel balance work surface  16  and any other objects that are not the subject of testing is subtracted to yield the drag for the bicycle alone. 
         [0025]    Testing of only the bicycle B as shown is sometimes conducted, such as might be useful to test its aerodynamic drag vs. a different bicycle or to test the same bicycle with different equipment configurations, such as, e.g., with different wheel sets. Many tests, however, include the combination of the bicycle and a mounted rider because the rider&#39;s drag is the greater component of the overall drag, and changes in the rider&#39;s position, helmet and clothing can yield significant reductions in drag. 
         [0026]    As shown, the bicycle&#39;s front wheel is positioned in contact with a front wheel roller  20  that protrudes through an opening in the surface  16 . Similarly, the rear wheel is positioned to contact a pair of rollers  22  that also protrude through an opening. The front wheel roller  20  and the rear wheel rollers  22  allow the bicycle to be “ridden in place” if desired at a selected speed during testing. Typically, data such as the rider&#39;s cadence, speed, power, etc. are collected during testing. 
         [0027]      FIG. 3  is a side elevation view showing a portion of the wind tunnel balance  10  and a portion of a new open area platform  30  mounted above and spaced apart from the surface  16 .  FIG. 4  is another side elevation view from a different vantage.  FIG. 5  is an exploded view of the platform  30  in its relation to the work surface  16  and the balance  10  (which is shown as a “black box” element in  FIG. 5 ). 
         [0028]    As shown in  FIGS. 3 and 5 , the open area platform  30  comprises a separate platform body  32  supported by platform adapter members  34  that are operatively coupled to the wind tunnel balance  10 . Specifically, (1) the wheel supports  12 ,  14  have been removed, (2) upper or first ends  36  of the platform adapter members  34  have been attached to a lower surface  40  of the platform body  32 , and (3) the platform  30  has been installed above the work surface  16  with lower or second ends  38  of the platform adapter members  34  extending through the openings  18  for coupling the platform  30  to the wind tunnel balance  10 . 
         [0029]    It is usually necessary to measure and account for the drag produced by the platform body  32  and platform adapter members  32 . This drag is many orders of magnitude less than the drag of a typical athlete and the athlete&#39;s equipment. In addition, due to the relatively smooth side profile of the platform  30  that does not undergo abrupt changes, such as in curvature, the variation in the amount of the platform&#39;s drag as the direction of the air stream changes is small. 
         [0030]    In the illustrated implementation, there are four platform adapter members  34 . In other implementations, however, it would be possible to use fewer adapter members (such as one or two such members), or a greater number of members. In the illustrated implementation, each adapter member  34  can be removably attached to the lower surface  40  for convenience. As best seen in  FIGS. 3 and 5 , each adapter member can comprise a base flange  44  attached to the lower surface  40  with fasteners and a tubular member  46  threadedly received in a central threaded aperture of the base flange  44 . In other implementations, the platform could be provided with recesses formed in the lower surface  40  for receiving the upper ends  36 , and the platform  30  would remain in the desired position under the action of gravity. 
         [0031]    The open area platform  30  provides a large open upper surface  42  upon which equipment for testing can be positioned, and generally without constraint. In the illustrated implementations, there are no dedicated supports mounted to the upper surface  42  requiring test subjects to be positioned at fixed locations on the upper surface (although such supports are possible, and could be removable). 
         [0032]    As a result, it is possible to test multiple bicycles (and mounted riders) simultaneously, such as, e.g., to evaluate riding formations. For example, testing can be conducted to evaluate a following rider&#39;s drag while directly aligned behind a leading rider (i.e., drafting the leading rider), such as to evaluate the following rider&#39;s position or the best following distance relative to a selected speed. In addition, testing could be conducted to test how drag is affected by changes in the relative positioning of riders in an echelon formation where the direction of the air stream is angled relative to the longitudinal axis of the bicycle and the following rider is positioned on the leeward side of, rather than directly behind, the lead rider. If necessary, the multiple bicycles can be supported on the open area platform by rear wheel stands or stationary trainers, which can be zeroed out to eliminate their effects on drag calculations. 
         [0033]    In addition to bicycles, the open area platform  30  allows for testing of other sports-related equipment and other objects. For example, as shown in  FIG. 6 , a skier S can be tested to evaluate his “tuck” position. Moreover, because the open area platform  30  does not rely on dedicated mounts, etc., that would clutter the open area, the skier S in  FIG. 6  is free to move to emulate the position of his body and skis to determine their effect on overall aerodynamic drag. For example, the skier can lean to the right as if making a right turn and position his skis on edge, which changes the aerodynamic drag of the skis and can have a measurable effect in elite competition. 
         [0034]    As just one other example, multiple short track speed skaters can use the open area platform  30  to study the effects of their relative positions and determine positive drafting benefits. Overall, testing with the open area platform provides a closer simulation to an actual sport because the athlete has the ability to move through all six degrees of freedom to very nearly the same extents as in a real-world sport scenario. 
         [0035]    Wind tunnel testing time is a limited resource, so saving time between testing runs can lead to important savings. The open air platform  30  can be quickly installed and removed so that it can be used in testing directly following a test conducted with the conventional arrangement of  FIGS. 1 and 2 , and then switched back to the conventional arrangement again. In the illustrated example, it may be necessary only to change over the support members  12 ,  14  and recalibrate the apparatus when changing arrangements. 
         [0036]    In view of the many possible embodiments to which the disclosed principles may be applied, it should be recognized that the illustrated embodiments are only preferred examples and should not be taken as limiting in scope. Rather, the scope of protection is defined by the following claims.