Systems and methods for operating a hydrofoil board with variable foil sweep

Abstract

A hydrofoil board is provided including a board having an upper surface and a lower surface. The upper surface is configured to support a user. The hydrofoil board further includes a mast extending from the lower surface and a hydrofoil system connected to the board by the mast. A propulsion system is configured to provide a propulsive force to the hydrofoil board and a foil structure is configured to provide a lifting force and comprises a pair of wings. Each of the pair of wings is movable through multiple sweep angles from a fully extended position wherein the pair of wings are each at a minimum sweep angle to a fully retracted position wherein the pair of wings are each at a maximum sweep angle. One or more controllers are configured to modify the sweep angles of the pair of wings to thereby modify the lifting force.

Description

FIELD

[0001] The present disclosure generally relates to controlling operation of a hydrofoil board, and more particularly to systems and methods for controlling position of a movable foil structure on a hydrofoil board.BACKGROUND

[0002] The following Patents and Patent Publications provide background information and are incorporated herein by reference, in entirety:

[0003] U.S. Pat. No. 10,647,392 is directed to a module configured for removable attachment to a board and attached to an end of a mast, where the mast supports a hydrofoil and a motor to drive the board. The module includes a connector for connecting to a power source, internal control circuitry, and a thermal bridge to thermally connect the control circuitry to the mast. The module comprises a watertight cavity in which the internal control circuitry is contained.

[0004] U.S. Pat. No. 11,453,465 is directed to a method for controlling a hydrofoil board powered by a motor driven propeller. The motor is controlled by a hand controller configured with user selectable operating pre-sets including a first operating pre-set, wherein the board is accelerated to a first speed which is less than that required for the board to hydrofoil, and a second operating pre-set, wherein the board is accelerated to a second speed sufficient for the board to hydrofoil. Alternatively, the operating pre-sets may limit the motor power. A system for operating a hydrofoil board is also disclosed, which includes a propulsion control unit comprising a propulsion source, and a hand controller configured to receive a first user input and a second user input and to transmit the user inputs to the propulsion control unit.

[0005] U.S. Pat. No. 11,479,326 is directed to a hydrofoil system having a fuselage with a propeller mounted to one end of the fuselage and a wing extending laterally from the fuselage. The fuselage is configured for removable attachment to a mast, so that the mast when attached extends from the fuselage in a direction substantially orthogonal to the longitudinal axis and also substantially orthogonal to the wing. A tail wing is connected to the fuselage by a tail strut, so that the tail wing is positioned beyond the end of the fuselage to which the propeller is attached. A motor is housed in the fuselage and has a cable connected thereto, the cable extending outside the fuselage, wherein a removable sealing system inhibits water ingress to the motor at the location where the cable is connected when the sealing system is installed in the fuselage.

[0006] WO2022174295 is directed to an electric powered watercraft, comprising a board, a battery, a motor, and a controller with an output, wherein an optical waveguide communicates light from the output to a deck of the board.

[0007] WO2022174296 is directed to a hydrofoil watercraft, comprising a board, a hydrofoil and a motor that are connected to the board by a mast, a battery module locatable in the board, the battery module comprising a battery and a first wireless communication device that are both located in a battery housing and a controller module locatable in the board. The controller module comprises a controller and a second wireless communication device that are both located in a controller housing wherein the battery module is configured to transmit battery status data using the first wireless communication device and the second wireless communication device is configured to receive the battery status data and relay the data to the controller.SUMMARY

[0008] This Summary is provided to introduce a selection of concepts that are further described below in the Detailed Description. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

[0009] According to one implementation of the present disclosure, a hydrofoil board is provided. The hydrofoil board includes a board having an upper surface and a lower surface. The upper surface is configured to support a user. The hydrofoil board further includes a mast extending from the lower surface and a hydrofoil system connected to the board by the mast. The hydrofoil system includes a propulsion system configured to provide a propulsive force to the hydrofoil board and a foil structure configured to provide a lifting force for the hydrofoil board and comprising a pair of wings. Each of the pair of wings is movable through multiple sweep angles from a fully extended position wherein the pair of wings are each at a minimum sweep angle to a fully retracted position wherein the pair of wings are each at a maximum sweep angle. The hydrofoil board further includes one or more controllers configured to modify the sweep angles of the pair of wings to thereby modify the lifting force for the hydrofoil board.

[0010] According to another implementation of the present disclosure, a method for controlling a hydrofoil board is provided. The method includes providing a hydrofoil board having a foil structure configured to provide a lifting force for the hydrofoil board and comprising a pair of wings. Each of the pair of wings is movable through multiple sweep angles from a fully extended position wherein the pair of wings are each at a minimum sweep angle to a fully retracted position wherein the pair of wings are each at a maximum sweep angle. The method further includes modifying the sweep angles of the pair of wings to thereby modify the lifting force for the hydrofoil board.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present disclosure is described with reference to the following Figures.

[0012] FIG. 1 illustrates an isometric view of a hydrofoil board with a foil structure having a pair of wings in a fully extended position.

[0013] FIG. 2 illustrates an isometric view of a hydrofoil board with a foil structure having a pair of wings in a fully retracted position.

[0014] FIGS. 3 and 4 illustrate top views of the foil structure in the fully extended and fully retracted positions.

[0015] FIG. 5 illustrates a hand controller that may be utilized in conjunction with the hydrofoil board of FIG. 1.

[0016] FIG. 6 illustrates a block diagram of the hydrofoil board of FIGS. 1 and 2.

[0017] FIGS. 7-9 illustrate methods for controlling the foil structure of the hydrofoil board of FIGS. 1 and 2.DETAILED DESCRIPTION

[0018] Existing foil structures utilized on hydrofoil boards for recreational watersports are often statically mounted and rigid, such that the lift / drag profile that is achievable with the hydrofoil board is fixed. In order to achieve a different lift / drag profile, the foil structure must be physically replaced, which adds cost and assembly time to the hydrofoil board and decreases the operator's enjoyment of the board. A static foil structure further means that the operator is not able to modify lift / draft profile during operation to accommodate both low speed operation in which a greater amount of stability is desired, and high speed operation in which greater maneuverability is appreciated.

[0019] The systems and methods of the present disclosure therefore provide a movable foil structure for a hydrofoil board in which the structure includes a pair of wings that are movable through multiple sweep angles between a fully extended position and a fully retracted position. While in the fully extended position ideal for lower speed operation, the sweep angle of the wings is at a minimum and the aspect ratio of the wings is at a maximum, resulting in a maximal amount of lift and stability for the hydrofoil board. As the speed of the board increases, an operator or an automatic foil adjustment system can move the wings to a fully retracted position ideal for higher speed operation. In the fully retracted position, the sweep angle of the wings is at a maximum and the aspect ratio of the wings is at a minimum, resulting in a reduction in lift and drag that decreases the risk of cavitation and provides greater maneuverability to the hydrofoil board. Because the foil structures on hydrofoil boards are generally large to accommodate the transition to foiling at lower speeds, such foils can provide an excess of lift at higher speeds, thereby requiring the operator to lean forward and decrease the angle of incidence on the foils to decrease lift in order to avoid ventilation of the foils. Advantageously, the variable sweep of the foil structure disclosed herein permits a reduction in lift without modification to the operator's position on the hydrofoil board.

[0020] Referring now to FIGS. 1 and 2, the hydrofoil board 10 has a board 12 with an upper surface or deck 14 that is suitable for a user to stand or lie on when in use. A mast 16 extends from a lower surface 18 of the board 12 and a hydrofoil system 20 is connected to the mast 16. In an exemplary implementation, the position of the mast 16 is fixed relative to the board 12. The hydrofoil system 20 includes a foil structure 22 and a propulsion system 24 that is configured to provide a propulsive thrust to the hydrofoil board 10.

[0021] The foil structure 22 includes a pair of movable main hydrofoil wings 28 and a static tail wing 30. The positions of the pair of movable hydrofoil wings 28 are adjusted via a foil adjustment mechanism 32 that may be located within the mast 16. The foil adjustment mechanism 32 could include any suitable type of drive system capable of rotating the wings 28 relative to the mast 16. For example, the foil adjustment mechanism 32 could include electric linear actuators or rotary actuators (e.g., servo motors). The foil adjustment mechanism 32 may drive a gear system located between the hydrofoil wings 28. In some embodiments, the gear system may be configured such that the hydrofoil wings 28 are rotated symmetrically relative to the mast 16. In other embodiments, the gear system may be configured such that each of the wings 28 is rotated independently by the foil adjustment mechanism 32. FIG. 1 depicts the pair of wings 28 in the fully extended position, while FIG. 2 depicts the pair of wings 28 in the fully retracted position. FIGS. 3 and 4 similarly depict top sectional views of the hydrofoil system 20 in the fully extended and fully retracted positions, respectively.

[0022] When the wings 28 are in a fully extended position (see FIGS. 1 and 3), the sweep angle of each wing θs is at a minimum value. Accordingly, the span 44 of the wings 28 is at its maximal value, as is the unretracted area 40 of the wings 28 (i.e., the area of the wings 28 that is not contained within or overlapping the mast 16). The retracted area 42 is also at its minimal value. By contrast, when the wings 28 are in the fully retracted position (see FIGS. 2 and 4), the sweep angle of each wing θs is at a maximum value. The span 44 of the wings 28 is at its minimal value, as is the unretracted area 40 of the wings 28. The retracted area 42 is also at its maximal value. These parameters determine the aspect ratio of a hydrofoil wing, which can be calculated from the following equation:λ=S2Awhere λ is the aspect ratio, S is the wing span, and A is the area of the wings. Because the span is squared term, the larger span 44 of the fully extended position depicted in FIGS. 1 and 3 results in a larger aspect ratio than the fully retracted position. A higher aspect ratio is further correlated with a greater lift coefficient, which is proportional to the amount of lift generated by the hydrofoil.

[0024] Turning now to FIG. 5, a hand controller 50 is depicted that can function as a user input device for the hydrofoil board 10, such as by receiving an input through a button 58 or trigger 54 and sending a wireless signal to a control system for the hydrofoil board 10 (e.g., controller 100, described below with reference to FIG. 6) to choose the level of thrust to be produced by the motor 24. The hand controller 50 may also be sent information from the control system for display to a user on a display device 56, such as a charge level of the battery, temperature, speed, and any other relevant parameters.

[0025] The hand controller 50 is shown to include a handle portion 52 for the user to grasp and a tether strap 60 that can be secured around the user's wrist to prevent loss of the hand controller 50 if the user were to lose grasp on the handle portion 52. The trigger 54 is accessible by a finger of the user's hand that is grasping the handle portion 52, and the trigger 54 may act as an accelerator or throttle, whereby variable levels of power / speed can be indicated by partially pressing the trigger 54. The buttons 58 are accessible by a user's thumb, and are configured to be actuated simultaneously while the user is operating the throttle trigger 54. In an exemplary implementation, the buttons 58 may be utilized to control the sweep angle θs of the wings and thereby move the wings between the fully extended and fully retracted positions. For example, buttons 58 may be utilized to toggle to wings 28 between the fully extended and fully retracted positions. In other implementations, a slider control may be provided on the hand controller 50 to permit the user to select between any potential sweep angle θs. In some embodiments, each of the wings 28 may be controlled separately by the hand controller 50. In other embodiments, the wings 28 are commanded only as a pair.

[0026] FIG. 6 depicts a block diagram of the control, power, communication and navigation systems of the hydrofoil board 10. The hydrofoil board 10 is shown to include a control system having a main controller 100. The main controller 100 is configured to communicate with and provide commands to a battery system 102, a wireless transmitter 104, a navigation system 106, and a foil adjustment system 108. The foil adjustment system 108 may include a controller configured to control the positions of the wings 28 via the foil adjustment mechanism 32. In various implementations, the foil adjustment system 108 may command the foil adjustment mechanism to change the positions of the wings 28 responsive to an operator command received from the hand controller 50 or an automatic command generated by the main controller 100.

[0027] The battery system 102 may include any suitable power storage system that is configured to store and provide power to the motor 24 and other devices of the hydrofoil board 10 (e.g., foil adjustment mechanism 32). In an exemplary implementation, the battery system 102 includes a battery controller configured to control the output from the battery system 102 and a battery suitable for marine applications. In other embodiments, another type of power storage technology (e.g., fuel cells) may be utilized. The wireless transmitter 104 is configured to be controlled by the controller 100 to transmit and receive communications with the hand controller 50. In various embodiments, the wireless transmitter 104 may utilize any suitable short range wireless communication protocol (e.g., Bluetooth, Bluetooth Low Energy (BLE)).

[0028] The navigation system 106 includes all of the systems and devices configured to provide information regarding the body of water in which the hydrofoil board 10 is traveling, and the current status of the hydrofoil board 10 (e.g., speed of the board 10 over water and / or over ground). For example, in various embodiments, the navigation system 106 may include a GPS device, accelerometers, a camera, a radar device, a sonar device, and / or a Lidar device.

[0029] In some embodiments, the hydrofoil board 10 further includes a pair of pair of weight sensors 110, 112. The weight sensors 110, 112 may be embedded within and positioned on opposite sides of the board 12 to sense the user's weight distribution on the board (e.g., whether the user has shifted their weight to one side of the board or the other, for example, when leaning into the direction of a turn to complete a turning operation). In some implementations, the weight sensors 110, 112 may be additionally be utilized as a control input to the main controller 100 to control a sweep angle θs of one of the pair of wings 28 if the wings are separately movable. For example, if the main controller 100 is operating in a roll stability mode, the main controller 100 may act to decrease the sweep angle θs of the wing 28 on the side that the user has shifted their weight in order to increase lift on that side of the board 12. For example, if the user shifts their weight portside, as detected by weight sensor 110, the main controller 100 may command the wing 28 located on the port side to decrease its sweep angle θs, thereby increasing lift on the port side of the board 12 and rolling the board 12 back towards the center. Alternatively, the main controller 100 could command the wing 28 located on the starboard side to increase its sweep angle θs, thereby decreasing lift on the starboard side of the board 12 and accomplishing the same result of rolling the board 12 back towards the center.

[0030] Referring now to FIGS. 7-9, methods for controlling the positions of the pair of movable hydrofoil wings 28 are depicted. FIGS. 7 and 8 depict methods 700 and 800 for controlling the positions of the movable hydrofoil wings 28 responsive to a speed parameter of the hydrofoil board 10. In an exemplary implementation, methods 700 and 800 are performed primarily by the controller 100 in communication with the foil adjustment system 108 and the foil adjustment mechanism 32. Method 700 commences at step 702, as the controller 100 operates the hydrofoil board 10 with the wings 28 in the fully extended position (see FIGS. 1 and 3). At step 704, the controller 100 determines whether a speed parameter of the hydrofoil board 10 exceeds a maximum extension threshold. In various exemplary embodiments, the speed parameter could be a measured speed over ground or measured speed over water value as determined by the navigation system 106, or it could be a speed parameter of the propulsion system 24 (e.g., a motor speed). In addition, in various embodiments, the maximum extension threshold value could be hardcoded into the system based on the characteristics of the hydrofoil board 10, or it could be adjusted by an operator. For example, a more experienced operator may wish to retract the wings 28 at a lower speed in order to gain maneuverability of the hydrofoil board 10.

[0031] If the controller 100 determines that the speed parameter of the board does not exceed the maximum extension threshold at step 704, process 700 reverts to step 702 and the main controller 100 continues to operate the hydrofoil board 10 with the wings 28 in the fully extended position. However, if the controller 100 determines that the speed parameter of the board does exceed the maximum extension threshold at step 704, method 700 proceeds and concludes at step 706 as the main controller 100 and the foil adjustment system 108 move the wings 28 to the fully retracted position (see FIGS. 2 and 4).

[0032] In a similar fashion, method 800 depicted in FIG. 8 commences at step 802, as the controller 100 operates the hydrofoil board 10 with the wings 28 in the fully retracted position (see FIGS. 2 and 4). At step 804, the controller 100 determines whether a speed parameter of the hydrofoil board 10 is below a minimum retraction threshold. In various exemplary embodiments, the speed parameter could be a measured speed over ground or measured speed over water value as determined by the navigation system 106, or it could be a speed parameter of the propulsion system 24 (e.g., a motor speed). If the controller 100 determines that the speed parameter of the board is not below the minimum retraction threshold at step 804, process 800 reverts to step 802 and the main controller 100 continues to operate the hydrofoil board 10 with the wings 28 in the fully retracted position. However, if the controller 100 determines that the speed parameter of the board is below the minimum retraction threshold at step 804, method 800 proceeds and concludes at step 806 as the main controller 100 and the foil adjustment system 108 move the wings 28 to the fully extended position (see FIGS. 1 and 3). The methods described in FIGS. 7 and 8 are merely exemplary, and in other implementations, additional extension and retraction thresholds may be utilized, as well as positions for the wings. For example, in method 700 a lower retraction threshold triggering movement of the wings 28 to a sweep angle θs between the fully extended and fully retracted positions could be utilized.

[0033] Turning now to FIG. 9, another method 900 for controlling the pair of movable hydrofoil wings 28 is depicted. In an exemplary implementation, method 900 is performed predominantly by the main controller 100 and the foil adjustment system 108. Method 900 commences at steps 902 and 904, as the main controller 100 determines target and actual lifting force values for the hydrofoil board 10. In some embodiments, target values for the lifting force may be stored in a lookup table in the main controller 100 based on the foiling speed of the hydrofoil 10. At step 906, the main controller 100 determines whether the actual lifting force exceeds the target lifting force by an error threshold amount (i.e., too much lift is being generated by the wings 28). If so, method 900 continues to step 908, and the main controller 100 and the foil adjustment system 108 modify the position of the wings 28 to increase the sweep angles, thereby reducing the aspect ratio of the wings 28 and decreasing the amount of generated lift.

[0034] However, if the main controller 100 determines that the actual lifting force does not exceed the target lifting force by an error threshold amount, method 900 proceeds to step 910. At step 910, the main controller 100 determines whether the target lifting force exceeds the actual lifting force by an error threshold amount (i.e., too little lift is being generated by the wings 28). If so, method 900 continues to step 912, and the main controller 100 and the foil adjustment system 108 modify the position of the wings 28 to decrease the sweep angles θs, thereby increasing the aspect ratio of the wings 28 and increasing the amount of generated lift. If the main controller 100 determines that the target lifting force does not exceed the actual lifting force by an error threshold amount, method 900 reverts to step 902 and concludes by continuing to operate the hydrofoil board 10 with the wings 28 in their present position.

[0035] This written description uses examples to disclose the invention, including the best mode, and to enable any person skilled in the art to make and use the invention. Certain terms have been used for brevity, clarity and understanding. No unnecessary limitations are to be inferred therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes only and are intended to be broadly construed. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have features or structural elements that do not differ from the literal language of the claims, or if they include equivalent features or structural elements with insubstantial differences from the literal languages of the claims.

Examples

Embodiment Construction

[0018]Existing foil structures utilized on hydrofoil boards for recreational watersports are often statically mounted and rigid, such that the lift / drag profile that is achievable with the hydrofoil board is fixed. In order to achieve a different lift / drag profile, the foil structure must be physically replaced, which adds cost and assembly time to the hydrofoil board and decreases the operator's enjoyment of the board. A static foil structure further means that the operator is not able to modify lift / draft profile during operation to accommodate both low speed operation in which a greater amount of stability is desired, and high speed operation in which greater maneuverability is appreciated.

[0019]The systems and methods of the present disclosure therefore provide a movable foil structure for a hydrofoil board in which the structure includes a pair of wings that are movable through multiple sweep angles between a fully extended position and a fully retracted position. While in the ...

FIELD

[0001] The present disclosure generally relates to controlling operation of a hydrofoil board, and more particularly to systems and methods for controlling position of a movable foil structure on a hydrofoil board.BACKGROUND

[0002] The following Patents and Patent Publications provide background information and are incorporated herein by reference, in entirety:

[0003] U.S. Pat. No. 10,647,392 is directed to a module configured for removable attachment to a board and attached to an end of a mast, where the mast supports a hydrofoil and a motor to drive the board. The module includes a connector for connecting to a power source, internal control circuitry, and a thermal bridge to thermally connect the control circuitry to the mast. The module comprises a watertight cavity in which the internal control circuitry is contained.

[0004] U.S. Pat. No. 11,453,465 is directed to a method for controlling a hydrofoil board powered by a motor driven propeller. The motor is controlled by a hand controller configured with user selectable operating pre-sets including a first operating pre-set, wherein the board is accelerated to a first speed which is less than that required for the board to hydrofoil, and a second operating pre-set, wherein the board is accelerated to a second speed sufficient for the board to hydrofoil. Alternatively, the operating pre-sets may limit the motor power. A system for operating a hydrofoil board is also disclosed, which includes a propulsion control unit comprising a propulsion source, and a hand controller configured to receive a first user input and a second user input and to transmit the user inputs to the propulsion control unit.

[0005] U.S. Pat. No. 11,479,326 is directed to a hydrofoil system having a fuselage with a propeller mounted to one end of the fuselage and a wing extending laterally from the fuselage. The fuselage is configured for removable attachment to a mast, so that the mast when attached extends from the fuselage in a direction substantially orthogonal to the longitudinal axis and also substantially orthogonal to the wing. A tail wing is connected to the fuselage by a tail strut, so that the tail wing is positioned beyond the end of the fuselage to which the propeller is attached. A motor is housed in the fuselage and has a cable connected thereto, the cable extending outside the fuselage, wherein a removable sealing system inhibits water ingress to the motor at the location where the cable is connected when the sealing system is installed in the fuselage.

[0006] WO2022174295 is directed to an electric powered watercraft, comprising a board, a battery, a motor, and a controller with an output, wherein an optical waveguide communicates light from the output to a deck of the board.

[0007] WO2022174296 is directed to a hydrofoil watercraft, comprising a board, a hydrofoil and a motor that are connected to the board by a mast, a battery module locatable in the board, the battery module comprising a battery and a first wireless communication device that are both located in a battery housing and a controller module locatable in the board. The controller module comprises a controller and a second wireless communication device that are both located in a controller housing wherein the battery module is configured to transmit battery status data using the first wireless communication device and the second wireless communication device is configured to receive the battery status data and relay the data to the controller.SUMMARY

[0008] This Summary is provided to introduce a selection of concepts that are further described below in the Detailed Description. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

[0009] According to one implementation of the present disclosure, a hydrofoil board is provided. The hydrofoil board includes a board having an upper surface and a lower surface. The upper surface is configured to support a user. The hydrofoil board further includes a mast extending from the lower surface and a hydrofoil system connected to the board by the mast. The hydrofoil system includes a propulsion system configured to provide a propulsive force to the hydrofoil board and a foil structure configured to provide a lifting force for the hydrofoil board and comprising a pair of wings. Each of the pair of wings is movable through multiple sweep angles from a fully extended position wherein the pair of wings are each at a minimum sweep angle to a fully retracted position wherein the pair of wings are each at a maximum sweep angle. The hydrofoil board further includes one or more controllers configured to modify the sweep angles of the pair of wings to thereby modify the lifting force for the hydrofoil board.

[0010] According to another implementation of the present disclosure, a method for controlling a hydrofoil board is provided. The method includes providing a hydrofoil board having a foil structure configured to provide a lifting force for the hydrofoil board and comprising a pair of wings. Each of the pair of wings is movable through multiple sweep angles from a fully extended position wherein the pair of wings are each at a minimum sweep angle to a fully retracted position wherein the pair of wings are each at a maximum sweep angle. The method further includes modifying the sweep angles of the pair of wings to thereby modify the lifting force for the hydrofoil board.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present disclosure is described with reference to the following Figures.

[0012] FIG. 1 illustrates an isometric view of a hydrofoil board with a foil structure having a pair of wings in a fully extended position.

[0013] FIG. 2 illustrates an isometric view of a hydrofoil board with a foil structure having a pair of wings in a fully retracted position.

[0014] FIGS. 3 and 4 illustrate top views of the foil structure in the fully extended and fully retracted positions.

[0015] FIG. 5 illustrates a hand controller that may be utilized in conjunction with the hydrofoil board of FIG. 1.

[0016] FIG. 6 illustrates a block diagram of the hydrofoil board of FIGS. 1 and 2.

[0017] FIGS. 7-9 illustrate methods for controlling the foil structure of the hydrofoil board of FIGS. 1 and 2.DETAILED DESCRIPTION

[0018] Existing foil structures utilized on hydrofoil boards for recreational watersports are often statically mounted and rigid, such that the lift / drag profile that is achievable with the hydrofoil board is fixed. In order to achieve a different lift / drag profile, the foil structure must be physically replaced, which adds cost and assembly time to the hydrofoil board and decreases the operator's enjoyment of the board. A static foil structure further means that the operator is not able to modify lift / draft profile during operation to accommodate both low speed operation in which a greater amount of stability is desired, and high speed operation in which greater maneuverability is appreciated.

[0019] The systems and methods of the present disclosure therefore provide a movable foil structure for a hydrofoil board in which the structure includes a pair of wings that are movable through multiple sweep angles between a fully extended position and a fully retracted position. While in the fully extended position ideal for lower speed operation, the sweep angle of the wings is at a minimum and the aspect ratio of the wings is at a maximum, resulting in a maximal amount of lift and stability for the hydrofoil board. As the speed of the board increases, an operator or an automatic foil adjustment system can move the wings to a fully retracted position ideal for higher speed operation. In the fully retracted position, the sweep angle of the wings is at a maximum and the aspect ratio of the wings is at a minimum, resulting in a reduction in lift and drag that decreases the risk of cavitation and provides greater maneuverability to the hydrofoil board. Because the foil structures on hydrofoil boards are generally large to accommodate the transition to foiling at lower speeds, such foils can provide an excess of lift at higher speeds, thereby requiring the operator to lean forward and decrease the angle of incidence on the foils to decrease lift in order to avoid ventilation of the foils. Advantageously, the variable sweep of the foil structure disclosed herein permits a reduction in lift without modification to the operator's position on the hydrofoil board.

[0020] Referring now to FIGS. 1 and 2, the hydrofoil board 10 has a board 12 with an upper surface or deck 14 that is suitable for a user to stand or lie on when in use. A mast 16 extends from a lower surface 18 of the board 12 and a hydrofoil system 20 is connected to the mast 16. In an exemplary implementation, the position of the mast 16 is fixed relative to the board 12. The hydrofoil system 20 includes a foil structure 22 and a propulsion system 24 that is configured to provide a propulsive thrust to the hydrofoil board 10.

[0021] The foil structure 22 includes a pair of movable main hydrofoil wings 28 and a static tail wing 30. The positions of the pair of movable hydrofoil wings 28 are adjusted via a foil adjustment mechanism 32 that may be located within the mast 16. The foil adjustment mechanism 32 could include any suitable type of drive system capable of rotating the wings 28 relative to the mast 16. For example, the foil adjustment mechanism 32 could include electric linear actuators or rotary actuators (e.g., servo motors). The foil adjustment mechanism 32 may drive a gear system located between the hydrofoil wings 28. In some embodiments, the gear system may be configured such that the hydrofoil wings 28 are rotated symmetrically relative to the mast 16. In other embodiments, the gear system may be configured such that each of the wings 28 is rotated independently by the foil adjustment mechanism 32. FIG. 1 depicts the pair of wings 28 in the fully extended position, while FIG. 2 depicts the pair of wings 28 in the fully retracted position. FIGS. 3 and 4 similarly depict top sectional views of the hydrofoil system 20 in the fully extended and fully retracted positions, respectively.

[0022] When the wings 28 are in a fully extended position (see FIGS. 1 and 3), the sweep angle of each wing θs is at a minimum value. Accordingly, the span 44 of the wings 28 is at its maximal value, as is the unretracted area 40 of the wings 28 (i.e., the area of the wings 28 that is not contained within or overlapping the mast 16). The retracted area 42 is also at its minimal value. By contrast, when the wings 28 are in the fully retracted position (see FIGS. 2 and 4), the sweep angle of each wing θs is at a maximum value. The span 44 of the wings 28 is at its minimal value, as is the unretracted area 40 of the wings 28. The retracted area 42 is also at its maximal value. These parameters determine the aspect ratio of a hydrofoil wing, which can be calculated from the following equation:λ=S2Awhere λ is the aspect ratio, S is the wing span, and A is the area of the wings. Because the span is squared term, the larger span 44 of the fully extended position depicted in FIGS. 1 and 3 results in a larger aspect ratio than the fully retracted position. A higher aspect ratio is further correlated with a greater lift coefficient, which is proportional to the amount of lift generated by the hydrofoil.

[0024] Turning now to FIG. 5, a hand controller 50 is depicted that can function as a user input device for the hydrofoil board 10, such as by receiving an input through a button 58 or trigger 54 and sending a wireless signal to a control system for the hydrofoil board 10 (e.g., controller 100, described below with reference to FIG. 6) to choose the level of thrust to be produced by the motor 24. The hand controller 50 may also be sent information from the control system for display to a user on a display device 56, such as a charge level of the battery, temperature, speed, and any other relevant parameters.

[0025] The hand controller 50 is shown to include a handle portion 52 for the user to grasp and a tether strap 60 that can be secured around the user's wrist to prevent loss of the hand controller 50 if the user were to lose grasp on the handle portion 52. The trigger 54 is accessible by a finger of the user's hand that is grasping the handle portion 52, and the trigger 54 may act as an accelerator or throttle, whereby variable levels of power / speed can be indicated by partially pressing the trigger 54. The buttons 58 are accessible by a user's thumb, and are configured to be actuated simultaneously while the user is operating the throttle trigger 54. In an exemplary implementation, the buttons 58 may be utilized to control the sweep angle θs of the wings and thereby move the wings between the fully extended and fully retracted positions. For example, buttons 58 may be utilized to toggle to wings 28 between the fully extended and fully retracted positions. In other implementations, a slider control may be provided on the hand controller 50 to permit the user to select between any potential sweep angle θs. In some embodiments, each of the wings 28 may be controlled separately by the hand controller 50. In other embodiments, the wings 28 are commanded only as a pair.

[0026] FIG. 6 depicts a block diagram of the control, power, communication and navigation systems of the hydrofoil board 10. The hydrofoil board 10 is shown to include a control system having a main controller 100. The main controller 100 is configured to communicate with and provide commands to a battery system 102, a wireless transmitter 104, a navigation system 106, and a foil adjustment system 108. The foil adjustment system 108 may include a controller configured to control the positions of the wings 28 via the foil adjustment mechanism 32. In various implementations, the foil adjustment system 108 may command the foil adjustment mechanism to change the positions of the wings 28 responsive to an operator command received from the hand controller 50 or an automatic command generated by the main controller 100.

[0027] The battery system 102 may include any suitable power storage system that is configured to store and provide power to the motor 24 and other devices of the hydrofoil board 10 (e.g., foil adjustment mechanism 32). In an exemplary implementation, the battery system 102 includes a battery controller configured to control the output from the battery system 102 and a battery suitable for marine applications. In other embodiments, another type of power storage technology (e.g., fuel cells) may be utilized. The wireless transmitter 104 is configured to be controlled by the controller 100 to transmit and receive communications with the hand controller 50. In various embodiments, the wireless transmitter 104 may utilize any suitable short range wireless communication protocol (e.g., Bluetooth, Bluetooth Low Energy (BLE)).

[0028] The navigation system 106 includes all of the systems and devices configured to provide information regarding the body of water in which the hydrofoil board 10 is traveling, and the current status of the hydrofoil board 10 (e.g., speed of the board 10 over water and / or over ground). For example, in various embodiments, the navigation system 106 may include a GPS device, accelerometers, a camera, a radar device, a sonar device, and / or a Lidar device.

[0029] In some embodiments, the hydrofoil board 10 further includes a pair of pair of weight sensors 110, 112. The weight sensors 110, 112 may be embedded within and positioned on opposite sides of the board 12 to sense the user's weight distribution on the board (e.g., whether the user has shifted their weight to one side of the board or the other, for example, when leaning into the direction of a turn to complete a turning operation). In some implementations, the weight sensors 110, 112 may be additionally be utilized as a control input to the main controller 100 to control a sweep angle θs of one of the pair of wings 28 if the wings are separately movable. For example, if the main controller 100 is operating in a roll stability mode, the main controller 100 may act to decrease the sweep angle θs of the wing 28 on the side that the user has shifted their weight in order to increase lift on that side of the board 12. For example, if the user shifts their weight portside, as detected by weight sensor 110, the main controller 100 may command the wing 28 located on the port side to decrease its sweep angle θs, thereby increasing lift on the port side of the board 12 and rolling the board 12 back towards the center. Alternatively, the main controller 100 could command the wing 28 located on the starboard side to increase its sweep angle θs, thereby decreasing lift on the starboard side of the board 12 and accomplishing the same result of rolling the board 12 back towards the center.

[0030] Referring now to FIGS. 7-9, methods for controlling the positions of the pair of movable hydrofoil wings 28 are depicted. FIGS. 7 and 8 depict methods 700 and 800 for controlling the positions of the movable hydrofoil wings 28 responsive to a speed parameter of the hydrofoil board 10. In an exemplary implementation, methods 700 and 800 are performed primarily by the controller 100 in communication with the foil adjustment system 108 and the foil adjustment mechanism 32. Method 700 commences at step 702, as the controller 100 operates the hydrofoil board 10 with the wings 28 in the fully extended position (see FIGS. 1 and 3). At step 704, the controller 100 determines whether a speed parameter of the hydrofoil board 10 exceeds a maximum extension threshold. In various exemplary embodiments, the speed parameter could be a measured speed over ground or measured speed over water value as determined by the navigation system 106, or it could be a speed parameter of the propulsion system 24 (e.g., a motor speed). In addition, in various embodiments, the maximum extension threshold value could be hardcoded into the system based on the characteristics of the hydrofoil board 10, or it could be adjusted by an operator. For example, a more experienced operator may wish to retract the wings 28 at a lower speed in order to gain maneuverability of the hydrofoil board 10.

[0031] If the controller 100 determines that the speed parameter of the board does not exceed the maximum extension threshold at step 704, process 700 reverts to step 702 and the main controller 100 continues to operate the hydrofoil board 10 with the wings 28 in the fully extended position. However, if the controller 100 determines that the speed parameter of the board does exceed the maximum extension threshold at step 704, method 700 proceeds and concludes at step 706 as the main controller 100 and the foil adjustment system 108 move the wings 28 to the fully retracted position (see FIGS. 2 and 4).

[0032] In a similar fashion, method 800 depicted in FIG. 8 commences at step 802, as the controller 100 operates the hydrofoil board 10 with the wings 28 in the fully retracted position (see FIGS. 2 and 4). At step 804, the controller 100 determines whether a speed parameter of the hydrofoil board 10 is below a minimum retraction threshold. In various exemplary embodiments, the speed parameter could be a measured speed over ground or measured speed over water value as determined by the navigation system 106, or it could be a speed parameter of the propulsion system 24 (e.g., a motor speed). If the controller 100 determines that the speed parameter of the board is not below the minimum retraction threshold at step 804, process 800 reverts to step 802 and the main controller 100 continues to operate the hydrofoil board 10 with the wings 28 in the fully retracted position. However, if the controller 100 determines that the speed parameter of the board is below the minimum retraction threshold at step 804, method 800 proceeds and concludes at step 806 as the main controller 100 and the foil adjustment system 108 move the wings 28 to the fully extended position (see FIGS. 1 and 3). The methods described in FIGS. 7 and 8 are merely exemplary, and in other implementations, additional extension and retraction thresholds may be utilized, as well as positions for the wings. For example, in method 700 a lower retraction threshold triggering movement of the wings 28 to a sweep angle θs between the fully extended and fully retracted positions could be utilized.

[0033] Turning now to FIG. 9, another method 900 for controlling the pair of movable hydrofoil wings 28 is depicted. In an exemplary implementation, method 900 is performed predominantly by the main controller 100 and the foil adjustment system 108. Method 900 commences at steps 902 and 904, as the main controller 100 determines target and actual lifting force values for the hydrofoil board 10. In some embodiments, target values for the lifting force may be stored in a lookup table in the main controller 100 based on the foiling speed of the hydrofoil 10. At step 906, the main controller 100 determines whether the actual lifting force exceeds the target lifting force by an error threshold amount (i.e., too much lift is being generated by the wings 28). If so, method 900 continues to step 908, and the main controller 100 and the foil adjustment system 108 modify the position of the wings 28 to increase the sweep angles, thereby reducing the aspect ratio of the wings 28 and decreasing the amount of generated lift.

[0034] However, if the main controller 100 determines that the actual lifting force does not exceed the target lifting force by an error threshold amount, method 900 proceeds to step 910. At step 910, the main controller 100 determines whether the target lifting force exceeds the actual lifting force by an error threshold amount (i.e., too little lift is being generated by the wings 28). If so, method 900 continues to step 912, and the main controller 100 and the foil adjustment system 108 modify the position of the wings 28 to decrease the sweep angles θs, thereby increasing the aspect ratio of the wings 28 and increasing the amount of generated lift. If the main controller 100 determines that the target lifting force does not exceed the actual lifting force by an error threshold amount, method 900 reverts to step 902 and concludes by continuing to operate the hydrofoil board 10 with the wings 28 in their present position.

[0035] This written description uses examples to disclose the invention, including the best mode, and to enable any person skilled in the art to make and use the invention. Certain terms have been used for brevity, clarity and understanding. No unnecessary limitations are to be inferred therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes only and are intended to be broadly construed. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have features or structural elements that do not differ from the literal language of the claims, or if they include equivalent features or structural elements with insubstantial differences from the literal languages of the claims.

Examples

Embodiment Construction

[0018]Existing foil structures utilized on hydrofoil boards for recreational watersports are often statically mounted and rigid, such that the lift / drag profile that is achievable with the hydrofoil board is fixed. In order to achieve a different lift / drag profile, the foil structure must be physically replaced, which adds cost and assembly time to the hydrofoil board and decreases the operator's enjoyment of the board. A static foil structure further means that the operator is not able to modify lift / draft profile during operation to accommodate both low speed operation in which a greater amount of stability is desired, and high speed operation in which greater maneuverability is appreciated.

[0019]The systems and methods of the present disclosure therefore provide a movable foil structure for a hydrofoil board in which the structure includes a pair of wings that are movable through multiple sweep angles between a fully extended position and a fully retracted position. While in the ...

Claims

1. A hydrofoil board comprising:a board having an upper surface and a lower surface, the upper surface configured to support a user;a mast extending from the lower surface;a hydrofoil system connected to the board by the mast, the hydrofoil system comprising:a propulsion system configured to provide a propulsive force to the hydrofoil board; anda foil structure configured to provide a lifting force for the hydrofoil board and comprising a pair of wings, each of the pair of wings being movable through a plurality of sweep angles from a fully extended position wherein the pair of wings are each at a minimum sweep angle to a fully retracted position wherein the pair of wings are each at a maximum sweep angle; andone or more controllers configured to modify the sweep angles of the pair of wings to thereby modify the lifting force for the hydrofoil board.

2. The hydrofoil board of claim 1, wherein modifying the sweep angles of the pair of wings to thereby modify the lifting force for the hydrofoil board comprises:operating each of the pair of wings in the fully extended position; andresponsive to a determination that a speed parameter of the hydrofoil board exceeds a maximum extension threshold, moving the pair of wings to the fully retracted position.

3. The hydrofoil board of claim 1, wherein modifying the sweep angles of the pair of wings to thereby modify the lifting force for the hydrofoil board comprises:operating each of the pair of wings in the fully retracted position; andresponsive to a determination that a speed parameter of the hydrofoil board is below a minimum retraction threshold, moving the pair of wings to the fully extended position.

4. The hydrofoil board of claim 1, wherein modifying the sweep angles of the pair of wings to thereby modify the lifting force for the hydrofoil board comprises:responsive to a determination that a decrease in the lifting force is required, moving the pair of wings to increase the sweep angles.

5. The hydrofoil board of claim 1, wherein modifying the sweep angles of the pair of wings to thereby modify the lifting force for the hydrofoil board comprises:responsive to a determination that an increase in the lifting force is required, moving the pair of wings to decrease the sweep angles.

6. The hydrofoil board of claim 1, wherein modifying the sweep angles of the pair of wings to thereby modify the lifting force for the hydrofoil board comprises:determining a target lifting force for the hydrofoil board;responsive to a determination that an actual lifting force exceeds the target lifting force by an error threshold; moving the pair of wings to increase the sweep angles.

7. The hydrofoil board of claim 1, wherein modifying the sweep angles of the pair of wings to thereby modify the lifting force for the hydrofoil board comprises:determining a target lifting force for the hydrofoil board;responsive to a determination that the target lifting force exceeds an actual lifting force by an error threshold; moving the pair of wings to decrease the sweep angles.

8. The hydrofoil board of claim 1, further comprising a hand controller, wherein the one or more controllers are configured to modify the sweep angles of the pair of wings responsive to signals received from the hand controller.

9. The hydrofoil board of claim 1, wherein the sweep angle of each of the pair of wings is individually controllable.

10. The hydrofoil board of claim 1, further comprising a pair of weight sensors configured to generate data regarding the user's weight distribution on the board, wherein the one or more controllers configured to modify the sweep angles of the pair of wings responsive to the weight distribution data.

11. A method for controlling a hydrofoil board, comprising:providing a hydrofoil board having a foil structure configured to provide a lifting force for the hydrofoil board and comprising a pair of wings, each of the pair of wings being movable through a plurality of sweep angles from a fully extended position wherein the pair of wings are each at a minimum sweep angle to a fully retracted position wherein the pair of wings are each at a maximum sweep angle; andmodifying the sweep angles of the pair of wings to thereby modify the lifting force for the hydrofoil board.

12. The method of claim 11, wherein modifying the sweep angles of the pair of wings to thereby modify the lifting force for the hydrofoil board comprises:operating each of the pair of wings in the fully extended position; andresponsive to a determination that a speed parameter of the hydrofoil board exceeds a maximum extension threshold, moving the pair of wings to the fully retracted position.

13. The method of claim 11, wherein modifying the sweep angles of the pair of wings to thereby modify the lifting force for the hydrofoil board comprises:operating each of the pair of wings in the fully retracted position; andresponsive to a determination that a speed parameter of the hydrofoil board is below a minimum retraction threshold, moving the pair of wings to the fully extended position.

14. The method of claim 11, wherein modifying the sweep angles of the pair of wings to thereby modify the lifting force for the hydrofoil board comprises:responsive to a determination that a decrease in the lifting force is required, moving the pair of wings to increase the sweep angles.

15. The method of claim 11, wherein modifying the sweep angles of the pair of wings to thereby modify the lifting force for the hydrofoil board comprises:responsive to a determination that an increase in the lifting force is required, moving the pair of wings to decrease the sweep angles.

16. The method of claim 11, wherein modifying the sweep angles of the pair of wings to thereby modify the lifting force for the hydrofoil board comprises:determining a target lifting force for the hydrofoil board;responsive to a determination that an actual lifting force exceeds the target lifting force by an error threshold; moving the pair of wings to increase the sweep angles.

17. The method of claim 11, wherein modifying the sweep angles of the pair of wings to thereby modify the lifting force for the hydrofoil board comprises:determining a target lifting force for the hydrofoil board;responsive to a determination that the target lifting force exceeds an actual lifting force by an error threshold; moving the pair of wings to decrease the sweep angles.

18. The method of claim 11, further comprising a hand controller, wherein the sweep angles of the pair of wings are modified responsive to signals received from a hand controller.

19. The method of claim 11, wherein the sweep angle of each of the pair of wings is individually controllable.

20. The method of claim 11, wherein the sweep angles of the pair of wings are modified responsive to weight distribution data received from a pair of weight sensors.

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