Abstract:
A self-propelled hydrofoil device having front and rear foils, a support structure and a steering mechanism. The device is preferably fabricated with a flexible steering and/or support member that permits the drive foil to move in an appropriate manner through water to propel the device forward. Various embodiments are disclosed.

Description:
FIELD OF THE INVENTION 
   The present invention relates to hydrofoil devices and, more specifically, to hydrofoil devices that may be configured for self propelled operation. 
   BACKGROUND OF THE INVENTION 
   Relevant prior art hydrofoil devices include the “Trampofoil” device disclosed in Swedish Design Patent no. 98-0088 and a Water Vehicle disclosed in U.S. Pat. No. 6,099,369 issued to Puzey. 
   The Trampofoil discloses a basic self-propelled hydrofoil device having a main foil in the rear and a steerable foil in the front. The &#39;369 patent issued to Puzey discloses a related device that has a biased pivot point located substantially above the rear foil, i.e., under the area at which a user stands when in use (FIG. 9, item 82, or FIG. 10, item 72). 
   Disadvantageous aspects of the Trampofoil device and the &#39;369 patent include that they may not permit the front edge of the rear or “drive” foil to tilt sufficiently downward in response to a driving leg thrust to adequately propel the craft forward. A significant amount of the downward leg force may thus be impaled upon the foil, rather than shearing through water—wasting significant driving energy. In addition, the steering shaft of the Trampofoil is made of fiberglass which bends not only in the direction of travel, but also laterally, making steering difficult. 
   Due to these and other disadvantageous aspects, the arrangement of the Trampofoil and that of the &#39;369 patent are difficult to use, particularly by lay persons. 
   A need thus exists for a hydrofoil device that may be configured for self-propelled operation and is relatively easy to use. A need also exists for a hydrofoil device that provides sufficient forward thrust for the energy expended by the downward thrust of an operators leg&#39;s (or other means). 
   SUMMARY OF THE INVENTION 
   Accordingly, the present invention is directed towards providing a hydrofoil device that provides ready forward movement in response to driving thrusts or a related force. 
   The present invention is also directed towards providing a self-propelled hydrofoil device that provides ready forward movement in response to the drive force of the legs of an operator. 
   Furthermore, the present invention is directed to a self-propelled hydrofoil device that provides a flexible, movable or pivotable support structure substantially forward of a user that causes the front portion of a drive wing to tilt to an appropriate orientation to readily achieve forward movement of the device in response to a drive thrust. 
   These and related objects of the present invention are achieved by use of a self-propelled hydrofoil device as described herein. 
   The attainment of the foregoing and related advantages and features of the invention should be more readily apparent to those skilled in the art, after review of the following more detailed description of the invention taken together with the drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a hydrofoil device  10  in accordance with the present invention. 
       FIG. 2  is a diagram of relative drive foil position during use. 
       FIGS. 3–7  are perspective views of other embodiments of a hydrofoil device in accordance with the present invention. 
   

   DETAILED DESCRIPTION 
   Referring to  FIG. 1 , a perspective view of a hydrofoil device  10  in accordance with the present invention is shown. Hydrofoil device  10  may include a forward located canard arrangement  20  and a rear or aft located drive foil  30 . 
   The canard  20  may include a plate or spoon  21  (which tracks the water surface) and a foil member  22 , or be otherwise arranged. The primary function of the canard is finding and locking onto the water surface and canards and like devices are known in the art. 
   The principal or drive foil  30  may be one of any suitable hydrofoil “wings” or “foils.” Such foils are known in the art. Drive foil  30  may be fixedly coupled to vertical members  33  which may be fixedly coupled to support bar  34 . Drive platform  60  is preferably configured to receive a standing human and may include two foot placement plates  62  or be otherwise arranged. Plates  62  are preferably fixedly coupled to bar  34  so that a downward thrust on the plates translates to a similar downward force asserted on foil  30 . Note that the plates may be located on the inside edge of support bar  34  such that the substantially downward thrust is first applied to the leading edge  31  of foil  30 . 
   The steering mechanism  40  may include a steering handle  41  coupled to a steering shaft  42  that is provided in sleeve  61 . The distal end of the shaft is pivotally coupled to canard  20  at pivot  23 . The steering mechanism is preferably coupled to the drive platform via a steering support shaft  62  and associated sleeve  61 . The support shaft and sleeve may be securely coupled to the drive platform, for example, to support bar  34 . 
   Shaft  42  preferably includes an upper section  44  and a lower section  45  that are coupled in such a manner that they may pivot or otherwise move relative to one another in such a manner as to achieve a downward tilt in the front edge  31  of drive foil  30 . 
     FIG. 1  illustrates upper and lower steering shaft sections  44 , 45  jointed at pivot  46  and bias into a given position by bias spring  47 . The relative movement of the two sections about pivot  46 , indicated as angle α, achieves a similar movement in the angle of attack, β, of leading edge  31  of foil  30 . Increases in α and thus β correspond to a more aggressive cutting of foil  30  into the water, thereby propelling hydrofoil device  10  forward. 
   As the thrust of a user is spent, the force of bias spring  47  causes upper and lower sections  44 , 45  to move towards their “rest position,” i.e., into closer alignment, thereby decreasing both α and β and ultimately causing leading edge  31  of foil  30  to move upward placing foil  30  back in position for another downward, forward propelling thrust. 
   Referring to  FIG. 2 , a diagram of relative drive foil position during use is shown. Position A is a glide or “steady-state” position as the foil glides through the water. Prior to a leg thrust a user preferably pushes oh steering handle  41 . This causes upper and lower sections  44 , 45  to move apart, i.e., out of alignment, increasing α (and β) and causing leading edge  31  to tip downward (Position B). The user then asserts a leg thrust on platform  60  causing tip  31  to descend further and causing the entire foil to descend into the fluid medium at an angle, pushing the craft forward against the resistance of the water. The position of foil  30  at this stage is shown is in Position C. As the thrust expires, the force of the bias spring begins to reduce α and β, causing the leading edge to begin to rise and the foil to pass through a substantially steady state position, but further submerged than in Position A (Position D). The leading edge then rises slightly (due in part to the surface finding properties of the canard) causing the foil to rise (Position E) and return to its steady-state position (Position F, and Position A), ready for the next thrust. 
   Note that while the upper and lower sections  44 , 45  are preferably moveable in a first dimension to facilitate a desired movement of leading edge  31 , they are sufficiently rigid from side to side or in a “steering dimension” to provide adequate steering. 
   Referring to  FIGS. 3–7 , other embodiments of a hydrofoil device in accordance with the present invention are shown. The devices illustrated in these figures are intended to illustrate aspects of the breadth of the present invention and in no way to limit the present invention to the illustrated embodiments. 
     FIG. 3  illustrates device  10 , but with a pivot arrangement in steering shaft  42  that is different from that shown in  FIG. 1 . In the embodiment of  FIG. 1 , the upper section  44  extends past pivot  46 . In the embodiment of  FIG. 3 , the lower section  45  extends past pivot  46 . Bias spring  47  in both the embodiments of  FIGS. 1 and 3  may be an expansion spring or other suitable means. 
     FIG. 4A  illustrates a perspective view (from below horizontal) of hydrofoil device  10  having a compression spring based pivot mechanism  70  in steering shaft  42 .  FIG. 4B  illustrates a close-up perspective view of the compression spring based pivot mechanism  70 . The embodiment of  FIGS. 4A–4B  provide a coupling member  71  that couples upper section  44  to lower section  45  via pivot  46 . A compression spring  72  is provided between the upper and lower sections  44 , 45  and adjacent pivot  46  such that it compresses in a manner that increases α and β and expands in a manner that decreases these two angles, such that foil  30  functions as discussed above. 
     FIG. 5  illustrates hydrofoil device  10 , albeit with a leaf spring type mechanism  81  coupled to pivotally connected sections  44 , 45 . The leaf spring  81  may be made of steel or fiberglass or other suitable material. It may be formed with loops at both ends which are then coupled to the respective shaft sections  44 , 45  by mounting pins. 
   Other mounting mechanisms may be used. Spring  81  functions in a manner similar to compression spring  72 . 
     FIG. 6  illustrate hydrofoil device  10 , albeit with a linear coil spring  82  coupled between shaft sections  44 , 45 . A support shaft  83  is provided internal to the coil spring and the lower end of support shaft  83  descends into lower section  45 . In use, coil spring  82  is compressed when a user pushes down on handle  41  and thrusts his or her leg downward on platform  60 . The leg thrust on platform  60  drives the front end  31  of foil  30  downward propelling the craft forward and subsequent expansion of spring  82  pulls foil front end  31  back up through positions D and E to Position F (see  FIG. 2 ). 
     FIG. 7  illustrates hydrofoil device  10 , albeit with a parallelogram or like coupling mechanism  85 . Mechanism  85  may include two cross-coupling members  86 , 87  and a spring or other bias member  88 . The device of  FIG. 7  operates in a manner similar to that described in  FIG. 6  (with the two steering shaft sections  44 , 45  toward or away from one another) and as elsewhere described herein. 
   The embodiments discussed above may be, but are not necessarily, formed of the following materials. The foils may be formed of aluminum or graphite or fiberglass or another suitable material. The frame is preferably formed of aluminum or another suitable material. Frame components may be welded together or otherwise joined as appropriate and known. The bias mechanisms may include metal or composite springs, rubber or other elastic materials, etc. The handles may include rubber. Plastic may be provided on corners, edges and tube ends, etc., to smooth rough edges, provide seals or join components, etc. Various fabrication materials and techniques are known in the art. 
   Note also that an alternative steering shaft arrangement can be provided. For example, the steering shaft may be a continues member (instead of two separate sections  44 , 45 ) that bends or moves in a similar manner, but is substantially rigid laterally so as to afford adequate steering. 
   While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as fall within the scope of the invention and the limits of the appended claims.