WATERCRAFT SYSTEM WITH LIFTING BODIES
A system for a watercraft with a lifting body. The watercraft system includes, in one example, a lifting body configured to couple to a hull of a watercraft and generate dynamic lift during watercraft operation. In the watercraft system, the lifting body includes multiple parabolic curves that define a leading edge of the lifting body and the lifting body has a chord that decreases from a center of the lifting body to each lateral edge of the lifting body.
The present application is a continuation-in-part of U.S. application Ser. No. 17/452,211, entitled “WATERCRAFT WITH LIFTING BODIES”, and filed on Oct. 25, 2021. U.S. application Ser. No. 17/452,211 claims priority to U.S. Provisional Application No. 63/107,378, entitled “WATERCRAFT WITH LIFTING BODIES”, and filed on Oct. 29, 2020. The entire contents of the above-listed applications are each hereby incorporated by reference for all purposes.
TECHNICAL FIELDThe present description relates generally to watercraft lifting bodies that generate buoyant lift and dynamic lift during watercraft operation.
BACKGROUND/SUMMARYHydrofoils and lifting bodies have been used in watercrafts to enhance various aspects of watercraft performance such as increasing seakeeping and sea-kindliness, which may be particularly useful for watercrafts that are intended to operate in rough prevailing seas. For instance, attempts have been made to design certain hydrodynamic lifting bodies to achieve increased added mass motion damping, reduced friction drag by increasing dynamic lift that reduces hull immersion and hull wetting, and increased wave excitation dampening.
The inventors have recognized a need to further increase seakeeping and the full load displacement of watercrafts in comparison to previous watercraft lifting bodies. To elaborate, the inventors have specifically recognized that further increasing the watercraft's full load displacement enables the watercraft to achieve increased payload and fuel capacity, increased watercraft efficiency, or some combination thereof. The inventors have also recognized a desire to enhance watercraft motion control using motion stabilizing systems that employ active control surfaces.
The inventors have developed a watercraft system to achieve at least a portion of the aforementioned watercraft performance characteristics. The watercraft system includes, in one example, a lifting body configured to attach to a hull of a watercraft and generate dynamic lift during watercraft operation. In the watercraft system, an aspect ratio of the lifting body is less than two. Further, in the watercraft system, the lifting body includes multiple parabolic curves that define a leading edge of the lifting body. Even further in the watercraft system, the lifting body has a chord that decreases from a center of the lifting body to each lateral edge of the lifting body. Additionally, in the watercraft system, the lifting body twists from a central section to each of the lateral edges. Designing the lifting body with the aforementioned characteristics allows the watercraft to achieve increased efficiency and increased full load operating displacement which correspondingly increases watercraft payload capacity. In particular, the lifting body described above mitigates bow wave making at lower speeds (e.g., critical speeds), increases dynamic lift, and generates strong downwash. Additionally, designing the lifting body with twist and a profile that tapers the chord and fore-aft cross-section decreases drag for a given lift and root bending moment, thereby increasing the hydrodynamic efficiency of the lifting body in comparison to previous lifting bodies. Utilizing the lifting body with a twist in conjunction with a tapered chord and fore-aft cross-section in the watercraft enhances aspects of the watercraft's handling performance. The watercraft's customer appeal may be expanded as result of the handling performance gains, efficiency gains, and increased payload capacity.
Further, in another example, a watercraft system is provided that includes a lifting body which is configured to generate dynamic lift during watercraft operation in addition to static lift, also referred to as buoyancy. The lifting body includes two opposing lateral portions that extend laterally outward and aft from a central section. Further, in the watercraft system, the two opposing lateral portions generate a greater amount of dynamic lift than the central section, which produces primarily static lift. The lifting body described above allows increased volume to be placed forward in the lifting body and allows a stronger restoring moment to be applied to the hull. Further, the central section may have a higher volume than the lateral portions, thereby increasing wave cancellation due to the forward placement of the higher volume central section. To elaborate, the lifting body's low-speed bulbous bow effect is enhanced, and the lifting body's bow wave drag at lower speeds is reduced.
In yet another example, a watercraft system is provided that includes a lifting body that is coupled to a watercraft hull and configured to generate dynamic lift during watercraft operation. The watercraft system further includes a hydrofoil that is coupled to the watercraft hull and positioned behind the lifting body in a fore-aft direction. Further, in the watercraft system, the hydrofoil has a higher vertical location on the watercraft hull in comparison to the lifting body. In this way, the lift is able to be distributed in a lifting body structure that can be effectively incorporated into larger watercrafts, if desired. However, it will be appreciated that the lifting body described above and the other lifting bodies described herein may be incorporated into a wide variety of watercrafts of varying sizes and types. Further, the use of the lifting body and the hydrofoil in the manner described above allows the downwash of the watercraft to be magnified, thereby reducing the watercraft's frictional drag due to hull unwetting.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.
Watercraft systems with lifting bodies that are designed to achieve increased efficiency, increased seakeeping, and enhanced watercraft control in comparison to previous lifting bodies are described herein. To elaborate, the lifting body technology described herein allows watercrafts to significantly increase their full load displacement (i.e., maximum loaded displacement without the impacts of increased resistance usually associated with overloaded watercraft) across a wide speed range. In broader terms, at low to moderate speeds (e.g., critical speeds where the Froude number (Fr)<0.6, in one specific example), the increase in watercraft full load displacement stems from the mitigation of bow wave generation. Conversely, at higher watercraft speeds, the lifting bodies generate dynamic lift, thereby causing the vessel to heave to a shallower operating draft and reduce hull immersion and compensate for any additional load. The diminished hull immersion mitigates both friction and pressure drag and reduces wake generation. Moreover, the stronger downwash generated by the lifting bodies at the bow (in comparison to previous lifting bodies) may cause the hull forebody (e.g., especially from the critical hull shoulder and aft therefrom) to be unwetted, thereby reducing pressure and friction drag. Additionally, the stronger downwash is able to cancel wave generation, and energy correspondingly, to reduce watercraft resistance. Still further, the lifting bodies described herein may also achieve a bulbous bow effect due to the added volume and displacement that is positioned forward of the bow, which provides destructive wave cancellation. Additionally, in some examples, the watercraft system may include an aft-balancing lift device. The lift from the lifting body generates a bow-up moment about the hull's center of gravity. The aft-balancing lift device functions to provide a restoring moment in relation to this bow-up moment. The aft-balancing device may take the form of an interceptor, a transom flap, a transom foil, a bilge foil, combinations thereof, and the like. In some examples, the lifting bodies may replace a bulbous bow in a watercraft or be added to a bulbous bow of a watercraft, in other examples. The lifting bodies may be attached to a hull of the watercraft using struts, in some embodiments. In these embodiments, the added mass from the lifting body strut and the lifting body itself counters undesirable watercraft motions (e.g., pitch, roll, and/or yaw), resulting in a more stable and efficient propulsion thrust line. This reduces the thrust loss component, which is known in the art as added resistance in a seaway. Still further, in some embodiments, watercraft motion control may be enhanced through the use of a motion stabilizing system in the watercraft. The motion stabilizing system may incorporate controllable trailing edge flaps on the lifting body and may also employ active control surfaces on the aft-balancing lift devices, in some cases.
US 2022/0135182 A1 to Loui et al. discloses different watercraft and lifting body configurations. The contents of US 2022/0135182 A1 are incorporated herein by reference.
The watercraft 100 includes a bow 106, a stern 108, a starboard side 110, and a port side 112. As described herein, fore refers to a direction extending toward the bow 106, while aft refers to a direction extending toward the stern 108. Additionally, inboard refers to a direction parallel to the y-axis, extending inward toward a centerline 114 of the watercraft 100. On the other hand, outboard refers to a direction parallel to the y-axis, extending outward away from the centerline 114 of the watercraft 100.
The watercraft 100 includes a single lifting body 102 in the illustrated example. However, additional lifting bodies, hydrofoils, combinations thereof, and the like may be included in the watercraft system in alternative examples, as discussed in greater detail herein with regard to
The lifting body 102 is designed to generate lift distribution profiles which taper near the lateral sides of the lifting body. The tapered lift distribution increases lifting body efficiency, seakeeping ability, and handling performance. Structural features which allow the lifting bodies to realize these the efficiency and handling performance gains are expanded upon herein.
The lifting body 102 may be directly coupled to the hull 104, in one example, or coupled to the hull using a strut or other suitable structures, in other examples. The lifting body 102 is designed to taper the lift generated during forward motion of the lifting body near the tips, as discussed in greater detail herein.
The watercraft 100 may further include a control system 150 with a controller schematically depicted at 152. The controller 152 may include memory 154 and a processor 156. The memory 154 may store instructions executable by the processor 156 to perform control strategies, such as maneuvering strategies. Furthermore, the controller 152 may further receive control inputs from a watercraft operator to maneuver the watercraft as well as various watercraft sensors. The memory may include known data storage mediums such as volatile and non-volatile memory, such as random access memory (RAM) and read only memory (ROM), respectively, and the like. Further, the processor may include one or more microprocessors. The controller 152 may send control signals, commands, etc. to controllable components such as the adjustment mechanism and receive signals from sensors and/or components in the watercraft. It will therefore be understood that the controller 152 may be in electronic communication (e.g., wired and/or wireless communication) with the sensors and controllable components.
The lifting body 102 may further include a control surface 210 (e.g., a flap) at a straight portion 211 of a trailing edge 212. The control surface 210 may be configured to be adjusted in response to control commands to alter the lift generated by the lifting body 102. In this way, watercraft control is enhanced. It will be appreciated that the straight portion 211 of the trailing edge 212 allows for integration of the control surface 210 into the lifting body 102. In one example, the control surface 210 may include, at its base, a pivot/hinge about which the control surface can rotate, structural reinforcement at pivot/hinge area, an actuator to induce rotation of control surface, a coupler between the actuator and the control surface (e.g., a pushrod, a lever, a gear, combinations thereof, etc.), and the like. In other examples, the control surface may have alternate components and/or configurations. For instance, the control surface may use shape memory alloys and the like.
The trailing edge 212 and the other trailing edges of the lifting bodies described herein may be conformal trailing edges. To elaborate, the lifting bodies may have a nonlinear spanwise twist distribution for compatibility with trailing edge flap integration. This enables the use of a constant spanwise cross-section flap with a straight, single horizontal axis of rotation. Further, lifting body fabrication is simplified due to the constant spanwise cross-section. Further, the discontinuities at the lifting body and the flap hinge location are reduced due to the non-linear spanwise lift distribution. Further, the flaps function as control surfaces to facilitate hydrodynamic performance gains across a wider range of operating conditions.
A center of lift 218 of the lifting body with regard to a fore-aft direction is further depicted in
A center 220 of the lifting body 102 with regard to a lateral direction is further indicated in
Viewing planes A-A′ and B-B′, shown in
In the example illustrated in
The lifting body 600 may further include a control surface 610 at straight portion 611 of a trailing edge 612. The control surface 610 may be configured to be adjusted in response to control commands from a controller to alter the lift generated by the lifting body 600. In this way, watercraft control is enhanced.
A center 620 of the lifting body 600 with regard to a lateral direction is further indicated in
Viewing planes C-C′ and D-D′, shown in
The lateral portions 1004 produce additional dynamic lift during lifting body operation. As such, the lifting body 1000 may achieve greater dynamic lift than the lifting bodies shown in
Further, the central section 1002 has a greater volume than the lateral portions 1004. Additionally, the central section 1002 has primarily static lift, in the illustrated example. Further, the central section 1002 has a more forward placement with regard to the lateral portions 1004 than the lifting bodies shown in
In the illustrated example, each of the lateral portions 1004 include a control surface 1007 (e.g., a flap) at a straight portion 1008 of a trailing edge 1010. The control surfaces 1007 may be configured to be adjusted in response to control commands to alter the lift generated by the lifting body 1000. As previously indicated, the straight section of the trailing edge allows for integration of the control surface into the lifting body. However, in other examples, the control surfaces may be omitted from the lifting body.
The lateral portions 1004 have a rearward position with regard to the central section 1002. To elaborate, a fore sweep angle 1012 and an aft sweep angle 1014 of the lateral portions 1004 are depicted in
A lateral width 1016 and a fore-aft length 1018 are depicted in
Further, a chord of the lifting body 1000 again decreases from a center 1022 of the lifting body to each of the lateral edges 1024 of the lifting body.
The lifting body 1000 shown in
The different lifting bodies described herein, when attached to a bow of a watercraft, generate a bow-up pitch moment at the center of gravity of the watercraft. This bow-up moment may be counteracted by a restoring moment from one of the aft lifting devices described herein. The further aft the center of lift of the lifting body moves, the smaller the bow-up moment for the same lift value. As such, the bow-up moment of the lifting body 1000 shown in
The watercraft 1100 further includes an aft lifting device 1106. The aft lifting device 1106 is positioned rearward of the lifting body 1000, in the illustrated example. The aft lifting device 1106 functions to counteract (e.g., balance) the bow-up moment that is generated by the lifting body 1000. In this way, the moments about the watercraft's center of gravity are effectively managed, thereby enhancing watercraft handling performance.
It will be appreciated, that the watercraft system 1600 and/or the other watercraft systems described herein may include additional hydrofoils which may be positioned vertically above and rearward of the hydrofoil 1604. Another hydrofoil 1605, rearward (in a fore-aft direction) of the hydrofoil 1604, is coupled to a hull 1607 in
The added mass from the strut 1610 and the hydrofoil 1604 counters undesirable ship motions (e.g., pitch, roll, and/or yaw) and results in a more stable and efficient propulsion thrust line. This reduces the thrust loss component, which is termed added resistance in a seaway. Watercraft motion control can be enhanced by employing a motion stabilizing system incorporating the controllable trailing edge flaps 1700, shown in
The watercraft lifting body technology described herein allows an increase in watercraft full load operating displacement from 20%-35%, in one specific use-case example, across a wide speed range. In general terms, at critical low speeds (e.g., Fr<0.6), the higher allowable displacement is due to the mitigation of bow wave making. At higher speeds, the lifting body and aft-balancing lift from devices such as interceptors, transom flaps, transom foils, bilge foils, or a combination thereof, generate dynamic lift between 20%-35% of the vessel's full load displacement, in certain use-case examples, causing the vessel to heave to a shallower operating draft, thereby reducing hull immersion. Having less hull immersed mitigates both friction and pressure drag and also reduces wake generation. The strong downwash at the bow generated by the lifting body causes the hull forebody (e.g., especially from the critical hull shoulder and aft therefrom) to be unwetted, thereby reducing pressure and friction drag. The downwash also suppresses spray formation, thereby further reducing drag therefrom. Furthermore, the downwash cancels wave energy/generation to reduce ship resistance. The lifting bodies described herein also achieve a bulbous bow effect due to the added volume/displacement positioned forward of the bow, which provides destructive wave cancellation. Further, the added mass from the lifting body strut and foil structure counters undesirable ship motions (e.g., pitch, roll, and/or yaw) that results in a more stable and efficient propulsion thrust line. This reduces the thrust loss component, which is termed added resistance in a seaway. Watercraft motion control can be enhanced by employing a motion stabilizing system incorporating controllable trailing edge flaps on the lifting body and also employing active control surfaces on the aft-balancing lift devices, if desired.
An axis system with an x-axis, y-axis, and z-axis is provided in
In the following paragraphs, the subject matter of the present disclosure is further described. In one aspect, a watercraft system is provided that comprises a lifting body configured to generate dynamic lift during watercraft operation; wherein the lifting body includes: two opposing lateral portions that extend laterally outward and aft from a central section; and wherein the two opposing lateral portions generate a greater amount of dynamic lift than the central section. In one example, the central section may have a fore-aft cross-section that differs in profile from a fore-aft cross-section of the two opposing lateral portions. In another example, joints may be formed at mechanical interfaces between the central section and the two opposing lateral portions and function as transition regions. In yet another example, the lifting body may be coupled to a bow of a hull. In another example, the central section may be incorporated into the hull as a bulbous bow. In yet another example, the watercraft system may further comprise an aft lifting device positioned aft of the lifting body. In another example, the watercraft system may further comprise a strut that attaches the lifting body to the hull. In another example, the opposing lateral portions may be positioned aft of the central section. In another example, the central section may be laterally narrower than each of the two opposing lateral portions. In yet another example, a chord of the lifting body may decrease from a center of the lifting body to each of the lateral edges; and the lifting body may twist from the center to each of the lateral edges.
In another aspect, a watercraft system is provided that comprises a lifting body coupled to a watercraft hull and configured to generate dynamic lift during watercraft operation; and a first hydrofoil coupled to the watercraft hull and positioned behind the lifting body in a fore-aft direction; wherein the first hydrofoil has a higher vertical location on the watercraft hull in comparison to the lifting body. In another example, the lifting body and/or the first hydrofoil may twist from a center to each lateral edge of the lifting body and/or the first hydrofoil. In yet another example, the lifting body and the first hydrofoil may include lateral tips that are coupled via fore-aft extensions. In yet another example, the lifting body may be incorporated into a bulbous bow. In another example, the watercraft system may further comprise at least one control surface positioned at a trailing edge of the lifting body and/or the first hydrofoil, wherein the control surface is configured to be adjusted in response to control commands to alter the lift generated by the lifting body and/or the first hydrofoil. In another example, the watercraft system may further comprise a second hydrofoil, wherein the first hydrofoil and the second hydrofoil are positioned on opposing lateral sides of the watercraft hull. In another example, the first hydrofoil and the second hydrofoil may have anhedral root sections. In yet another example, the lifting body may include: two opposing lateral portions that extend laterally outward and aft from a central section; and the two opposing lateral portions generate a greater amount of dynamic lift than the central section. In another example, the watercraft system may further comprise an aft-balancing lift device coupled to a hull of the watercraft and configured to balance lift that is generated by the lifting body and the first hydrofoil. In yet another example, the lifting body may be coupled to a bow of a hull.
It will be appreciated that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not to be considered in a limiting sense, because numerous variations are possible. For example, the above technology can be applied to jet boats, propeller boats, and other types of watercrafts which use a variety of propulsion systems. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein.
The following claims particularly point out certain combinations and sub-combinations regarded as novel and non-obvious. These claims may refer to “an” element or “a first” element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and/or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, also are regarded as included within the subject matter of the present disclosure.
Claims
1. A watercraft system, comprising:
- a lifting body configured to generate dynamic lift during watercraft operation;
- wherein the lifting body includes: two opposing lateral portions that extend laterally outward and aft from a central section; and
- wherein the two opposing lateral portions generate a greater amount of dynamic lift than the central section.
2. The watercraft system of claim 1, wherein the central section has a fore-aft cross-section that differs in profile from a fore-aft cross-section of the two opposing lateral portions.
3. The watercraft system of claim 2, wherein joints are formed at mechanical interfaces between the central section and the two opposing lateral portions and function as transition regions.
4. The watercraft system of claim 1, wherein the lifting body is coupled to a bow of a hull.
5. The watercraft system of claim 4, wherein the central section is incorporated into the hull as a bulbous bow.
6. The watercraft system of claim 4, further comprising an aft lifting device positioned aft of the lifting body.
7. The watercraft system of claim 1, further comprising a strut that attaches the lifting body to the hull.
8. The watercraft system of claim 2, wherein the opposing lateral portions are positioned aft of the central section.
9. The watercraft system of claim 2, wherein the central section is laterally narrower than each of the two opposing lateral portions.
10. The watercraft system of claim 1, wherein:
- a chord of the lifting body decreases from a center of the lifting body to each of the lateral edges; and
- the lifting body twists from the center to each of the lateral edges.
11. A watercraft system, comprising:
- a lifting body coupled to a watercraft hull and configured to generate dynamic lift during watercraft operation; and
- a first hydrofoil coupled to the watercraft hull and positioned behind the lifting body in a fore-aft direction;
- wherein the first hydrofoil has a higher vertical location on the watercraft hull in comparison to the lifting body.
12. The watercraft system of claim 11, wherein the lifting body and/or the first hydrofoil twists from a center to each lateral edge of the lifting body and/or the first hydrofoil.
13. The watercraft system of claim 11, wherein the lifting body and the first hydrofoil include lateral tips that are coupled via fore-aft extensions.
14. The watercraft system of claim 11, wherein the lifting body is incorporated into a bulbous bow.
15. The watercraft system of claim 11, further comprising at least one control surface positioned at a trailing edge of the lifting body and/or the first hydrofoil, wherein the control surface is configured to be adjusted in response to control commands to alter the lift generated by the lifting body and/or the first hydrofoil.
16. The watercraft system of claim 11, further comprising a second hydrofoil, wherein the first hydrofoil and the second hydrofoil are positioned on opposing lateral sides of the watercraft hull.
17. The watercraft system of claim 16, wherein the first hydrofoil and the second hydrofoil have anhedral root sections.
18. The watercraft system of claim 11, wherein the lifting body includes:
- two opposing lateral portions that extend laterally outward and aft from a central section; and
- the two opposing lateral portions generate a greater amount of dynamic lift than the central section.
19. The watercraft system of claim 11, further comprising an aft-balancing lift device coupled to a hull of the watercraft and configured to balance lift that is generated by the lifting body and the first hydrofoil.
20. The watercraft system of claim 11, wherein the lifting body is coupled to a bow of a hull.
Type: Application
Filed: Sep 18, 2024
Publication Date: Jan 9, 2025
Inventors: Steven Loui (Honolulu, HI), Emile Suehiro (Honolulu, HI), Gary Shimozono (Honolulu, HI), Scott Yamashita (Honolulu, HI)
Application Number: 18/889,232