NO20241012A1

NO20241012A1 - A hydrofoil vessel

Info

Publication number: NO20241012A1
Application number: NO20241012A
Authority: NO
Inventors: Lars Arne Bleie
Original assignee: Scalesia As
Priority date: 2023-10-24
Filing date: 2024-10-09
Publication date: 2025-04-25
Also published as: NO20231124A1; NO348590B1; WO2025089965A1

Description

A hydrofoil vessel

Field of the invention

The present invention relates to a hydrofoil vessel comprising several hydrofoils, each hydrofoil having a wing arranged to be submerged in water, such that the vessel is raised above water when cruising, said wings being connected to a hull of the vessel by upright struts.

Background of the invention

Through their foils, hydrofoil boats can significantly reduce friction in water compared to conventional hulls. This is knowledge known since the beginning of the last century. However, the potential and possibilities of this have only now been realized through sailboats that go over 60 knots.

It is especially the submerged foils that have proved interesting as comfort and performance are better than hydrofoils that cut the surface. Submerged foils are nevertheless technically complicated as they require active control systems which make them expensive to both produce and maintain.

Hydrofoils are horizontal wings that such vessels rest on above water when cruising. The vertical uprights are called struts. Such vessels are subject to physical effects from waves, wind, or other changes in the center of gravity which means that the steering system must respond to maintain balance. This is done with flaps or by changing the angle of attack of wings on vessels with active steering systems.

Disclosure of the state of art

US 3117546 A discloses a watercraft of the type comprising one or more cavitating or non-cavitating, preferably fully submerged hydrofoils which extend transversely and carry the weight of the hull, and an automatic control system which regulates the extent to which the foil or foils are submerged in water when the watercraft is in motion, and which also improves the seaworthiness of the watercraft. The hydrofoils are horizontally arranged foils equipped with apertures, and the foils are connected to the watercraft by vertically struts extending up to an outrigger or wing on the watercraft. Said struts can also be equipped with orifices arranged on the side wall of the struts.

US 3146751 A discloses an automatic control device serving to maintain the immersion depth of fully submerged hydrofoils or hydrofoils of which only small parts are emerging, both being attached to a watercraft and serving furthermore to reduce rolling and pitching motions as well as vertical accelerations of such craft in a seaway.

US 3885513 A discloses an automatic mechanism for preventing cavitation at hydrofoils and flow bodies fed with air at the surface thereof from air exit openings. Rows of such air exit openings are arranged at locations of greatest excess speed at the foil profile or flow body, and that such rows are coupled with an air admission valve opened by negative pressure in opposition to an adjustable closing force. The closing force is calculated such that the valve opens and admits air from the atmosphere when a predetermined pressure has been attained.

Objects of the present invention

The present invention aims to provide a combined passive stabilization and control system with energy saving design in one design. It involves a great simplification as the system does not require supplied energy or need moving parts.

The invention combines stabilization, draft control together with drag reduction in one design.

Instead of using flaps to account for physical effects from waves, wind, or other changes, to maintain balance, the present invention uses air preferably released on an upper part of the horizontal wings of the hydrofoils.

A basic idea of the invention is to provide a fixed structure/design placed at the end of the horizontal wings of the hydrofoil vessel. Such a vessel could possibly need at least two, one on each side of the vessel. It thus comprises a system of independent devices with a drag-reducing design.

Hence, an object of the invention is to provide a passive system without moving parts for control of a hydrofoil vessel, as the buoyancy of the hydrofoil is reduced when the air openings in the winglets come above the surface and take in air.

Summary of the invention

According to the invention, a hydrofoil vessel comprising several hydrofoils is provided, each hydrofoil having a wing arranged to be submerged in water, such that the vessel is lifted above water when cruising, said wings being connected to a hull of the vessel by upright struts. Each wing comprises an upright winglet connected to the wing, said upright winglet having an air intake connected with air outlet apertures on the wing.

In one embodiment, the air intake is provided in a tip of the winglet.

The air outlet apertures can be provided on an upper part of the horizontal wing.

The air outlet apertures can be provided closer to a leading edge than a trailing edge of the horizontal wing.

Further, the upright winglet can be curved backwards, with a leading edge of the winglet having a convex shape and a trailing edge of the winglet having a concave shape.

The horizontal wing and the winglet can each be hollow, allowing air flow from the air intake in the winglet and to the air outlet apertures in the horizontal wing.

The horizontal wing and the winglet may also comprise an air flow channel connecting the air intake and the air outlet apertures, allowing air flow from the air intake in the winglet and to the air outlet apertures in the horizontal wing.

The air outlet apertures can be a series of holes or slits in the horizontal wing.

The upright winglet is arranged to penetrate a water surface of the water, allowing air to be sucked in through the air intake of the winglet.

The upright winglet can comprise a nearly planar, straight section joined to the outer end of the horizontal wing through a curved transition section having prescribed curvature limits.

The horizontal wing may comprise drainage holes for drainage of water.

The wing can be a horizontal wing, wherein the winglets are connected to an outer end of the wing.

The vessel can comprise a pair of front horizontal wings with winglets on their ends, and wherein each wing comprises several struts connecting the wing to the vessel. The winglets can in some embodiments be integrated with the struts connecting the wing to the vessel.

Further, all or part of the wing can be is arranged angled with respect to a horizontal plane.

The angled wing is preferably inclining outwards, and the winglet on an inner end of the angled wing can thus be higher than the winglet on an outer end of the angled wing.

One or more of said struts can also be arranged angled with respect to a vertical axis.

Description of the figures

Embodiments of the present invention will now be described, by way of example only, with reference to the following figures, wherein:

Figure 1 shows illustrative an overview of a hydrofoil vessel according to the invention.

Figure 2 shows illustrative a horizontal wing with a winglet supported on a hull of the vessel.

Figure 3 shows illustrative the horizontal wing with the winglet in the water. Figure 4 shows a partial cutaway section of the horizontal wing and winglet. Figures 5-10 show further embodiments of the present invention.

Description of preferred embodiments of the invention

Fig, 1 shows illustrative a hydrofoil vessel 10 having several hydrofoils 20 for raising the vessel 10 above the water 16 when cruising at optimal speed. The hydrofoils 20 are connected to an underside of a hull 12 of the vessel by upright struts 14, and the hydrofoils 20 are submerged in the water 16 during use.

The vessel 10 can be a conventional manned vessel or for instance an uncrewed surface vessel (USV).

The hydrofoils 20 in fig.1 comprises an embodiment with horizontal wings 22, wherein the struts 14 connects the hull 12 and the horizontal wings 22. The hydrofoils 20 further comprises an upright winglet 24 connected to an outer end 22c of each horizontal wing 22.

The upright winglet 24 can be almost right-angled, as illustrated in the figures, or the winglet 24 can be connected to the outer end 22 of the horizontal wing 22 at a desired angle. Hence, the term “upright” covers angles also other than right-angled.

The winglet 24 can for instance in one embodiment be of blended winglet type, which provides minimum induced drag for a given surface size. The winglet 24 consists of a nearly planar, straight section joined to the outer end 22c of the horizontal wing 22 through a curved transition section 32. The winglet transition section 32 having prescribed curvature limits providing surface aerodynamic loadings required for minimum drag. Radius of the curvature can for instance be 50-1000mm and/or the angle between the horizontal wing 22 and the winglet 24 can for instance be 90-120 degrees.

The hydrofoil vessel 10 as shown in fig.1 and 2 comprises hydrofoils 20 with at least a pair of front horizontal wings 22 and winglets 24 and at least a pair of rear horizontal wings 22 and winglets 24, wherein the horizontal wings 22 of each pair can be interconnected with each other.

The upright winglet 24 is equipped with one or more air intake(s) 28 and which is/are arranged to penetrate the water surface of the water 16. The air intake(s) 28 is/are connected with or communicates with air outlet apertures 26 on the horizontal wing 22.

When the vessel 10 is at rest the entire system will be filled with water. When the vessel 10 starts to move, the horizontal wing 22 acts like a conventional wing and will lift the vessel 10 out of the water 16. Water has an inertia in contrast to air which means that the lift is not significantly weakened by the flow through. At some point, the air intake 28 will come above the water level.

During speed, the water and waves will open up and close the air intake 28 to the extent needed to maintain altitude. When the vessel 10 goes too deep, the air intake 28 will be closed by the water flow and create an ordinary wing underwater, which in turn creates lift. The vessel 10 will lift until the air intakes 28 come over the water surface of the water 16 and sucks air in and down to the air outlet apertures 26 on the horizontal wings 22 and "punctures" the lift. This is repeated until the vessel 10 is stabilized.

As there is negative pressure on the upper side of the horizontal wing 22 at speed, the water will always be sucked out of the system. When air escapes the air outlet apertures 26 on the upper side of the wing 22, the lift will be weakened.

To achieve said effect, the air intake 28 is preferably provided in or adjacent a tip 24c of the winglet 24, which then penetrates the water surface as mentioned. However, the air intake 28 could possibly also be provided on the backside, frontside, or on the sides, of the winglets 24, as long as the desired effect is achieved.

Since there are several such hydrofoils 20 on the vessel 10, the average height above water of the entire vessel 10 will be determined by the air intakes 28.

Further, when several such wings 22 "work" independently of each other, it is the sum of all that determines the vessel's 10 height above the water.

The air outlet apertures 26 can be a series of holes or slits in the horizontal wing 22, and which preferably are provided on an overside of the horizontal wing 22.

However, the air outlet apertures 26 can possibly also be provided on the underside of the wing 22.

As seen in fig.2 and 3, the air outlet apertures 26 can be provided closer to a leading edge 22a than a trailing edge 22b of the horizontal wing 22. The air flow out of the air outlet apertures 26 in the horizontal wing 22 is illustrated by the arrows pointing backwards.

The horizontal wing 22 and the winglet 24 can in one embodiment each be hollow, thus allowing air flow from the air intake 28 in the winglet 24 and to the air outlet apertures 26 in the horizontal wing 22.

However, it is also possible that the horizontal wing 22 and the winglet 24 comprises an air flow channel 30 connecting the air intake 28 and the air outlet apertures 26, allowing air flow from the air intake 28 in the winglet 24 and to the air outlet apertures 26 in the horizontal wing 22. In the latter case, a manifold can be used to distribute the air flow from the channel to the air outlet apertures 26 in the horizontal wing 22.

Fig. 4 shows an example of the horizontal wing 22. In case it is needed, the hollow section of the horizontal wing 22 can comprise drainage holes for drainage of water. The drainage holes could suitably be placed at the lower most point or place in the hollow part.

Fig. 4 also shows the air flow channel 30 connecting the air intake 28 in the winglet 24 and the air outlet apertures 26 embedded in the horizontal wing 22.

The design of the upright winglets 24 can be backwards curved so that floating objects do not get stuck or cover the air intakes 28. As seen particularly in fig.3, the upright winglet 24 is curved backwards, with a leading edge 24a of the winglet 24 having a convex shape and a trailing edge 24b of the winglet 24 having a concave shape.

The design of hydrofoils 20 according to the invention will also have a positive effect on drag through reduced wingtip vortex. The “pigtail” in the drawings illustrates wingtip vortex. The figures show upright backwards leaning winglet 24, but which can have several variations and different designs. This also applies to the winglet ends (the tip 24c) themselves. Such winglets have significant gains in the form of reduced drag.

The leading edge 24a and the trailing edge 24b can have a varying streamwise spacing and varying monotonically within prescribed limits whereby the formation of vortices and areas of flow separation are prevented.

The wing configuration and wingtip vortex from the front wings can be utilized by rear wings in that they also create lift for the rear wings, as illustrated in fig.3.

Fig. 1-4 basically illustrates horizontal wings. Due to practical reasons, account must be taken of the fact that the front wings of smaller vessels may be angled, for instance from 0 to 20 degrees, when viewed from the front.

The vessel thus retains stability during the take-off transition to air-regulated march. The challenge is that the angle of attack during "take off" is often large (the bow points up). Together with the system being emptied of water a little too late, this means that the front wings may go too high and out of the water. When the lift ends, the bow turns down again in the opposite direction, with the risk of the vessel colliding with the water as the system does not have time to work. An angled front wing will dampen this movement. Angled wings will also "feed" the wing with air in a more controlled way as air comes out from the outermost holes only when internal water collects at the lowest point due to gravity.

Fig. 5-10 illustrates further embodiments of the invention, wherein the wings 22 are horizontal or angled with respect to a horizontal plane. The air inlet 28 in the winglet 24 and the air outlet apertures 26 in the wing 22, and possibly the air flow channel 30 connecting the air intake 28 and the air outlet apertures 26, is similar to what is disclosed in relation to fig.1-4.

Fig. 5 shows a vessel 12 with a rear hydrofoil 20 having a similar design as the ones discloses in relation to fig.1-4, i.e. with a horizontal wing 22 connected to the hull of the vessel 12 by the struts 14, and upright winglets 24 on the ends of the wing 22. The front hydrofoils 20 have two horizontal wings 22 with winglets 24 on its ends. Two struts 14 connects each wing 22 to the hull of the vessel 12.

Fig. 6 shows a vessel 12 with a rear hydrofoil 20 having a similar design as the ones discloses in relation to fig.1-4, i.e. with a horizontal wing 22 connected to the hull of the vessel 12 by the struts 14, and upright winglets 24 on the ends of the wing 22. The front hydrofoil 20 has two horizontal wings 22 with winglets 24 on the ends. Two struts 14 connects each wing 22 to the hull of the vessel 12. The winglets 24 are in this embodiment integrated with the struts 14, and the struts 14 are connected to the end of the wing 22 and to the hull of the vessel 12. The air inlet 28 can be on the outside or the inside of the strut 14.

Fig. 7 shows a vessel 12 with a rear hydrofoil 20 basically having a similar design as the front hydrofoil of fig.6, i.e. with horizontal wings 22 connected to the hull of the vessel 12 by the struts 14 at the end of the wings 22, and winglets 24 integrated with the struts 14. The front hydrofoil 20 has two angled and inclined wings 22 with winglets 24 on the ends. The wings 22 can have an angle between 0 and 20 degrees and is inclined in a sideways direction away from the vessel 12. Two struts 14 at the ends of the wing 22 connects the wing 22 to the hull of the vessel 12. The air inlet 28 can be on the outside or the inside of the strut 14. The winglets 24 can have different hight, wherein the inner winglet 24 is higher than the outer winglet 24, and hence the inner winglet 24 penetrates the water surface on the same level as the outer winglet 24.

Fig. 8 shows a vessel 12 with rear and front hydrofoils 20 having a similar design as the front hydrofoil of fig.7. Both the rear and front hydrofoil 20 has angled and inclined wings 22 with winglets 24 on the ends. The wing 22 can have an angle between 0 and 20 degrees and is inclined in a sideways direction away from the vessel 12. Two struts 14 at the ends of the wing 22 connects the wing 22 to the hull of the vessel 12. The air inlet 28 can be on the outside or the inside of the strut 14. The winglets 24 can have different hight, wherein the inner winglet 24 is higher than the outer winglet 24, and hence the inner winglet 24 can penetrate the water surface on the same level as the outer winglet 24.

Fig. 9 shows a vessel 12 with a rear hydrofoil 20 having a design that resembles the rear hydrofoil of fig.7, i.e. with a horizontal wing 22 connected to the hull of the vessel 12 by the struts 14 at the end of the wing 22, and winglets 24 integrated with the struts 14. The front hydrofoil 20 is similar to the front hydrofoils 20 of fig.7 and 8, and it has two angled and inclined wings 22 with winglets 24 on the ends. The wing 22 can have an angle between 0 and 20 degrees and is inclined in a sideways direction away from the vessel 12. Two struts 14 at the ends of the wing 22 connects the wing 22 to the hull of the vessel 12. The air inlet 28 can be on the outside or the inside of the strut 14. The winglets 24 can have different hight, wherein the inner winglet 24 is higher than the outer winglet 24, and hence the inner winglet 24 can penetrate the water surface on the same level as the outer winglet 24.

Fig. 10 shows a vessel 12 with a rear hydrofoil 20 having two horizontal wings 22 connected to the hull of the vessel 12 by the struts 14 at the end of the wing 22, and winglets 24 integrated with the struts 14. The inner strut 14, and possibly the outer strut 14, is however not vertical but is angled with respect to a vertical axis. The front hydrofoil 20 has two angled and inclined wings 22 with winglets 24 on the ends. The wing 22 can have an angle between 0 and 20 degrees and is inclined in a sideways direction away from the vessel 12. Two struts 14 at the ends of the wing 22 connects the wing 22 to the hull of the vessel 12. The air inlet 28 can be on the outside or the inside of the strut 14. The winglets 24 can have different hight, wherein the inner winglet 24 is higher than the outer winglet 24, and hence the inner winglet 24 can penetrate the water surface on the same level as the outer winglet 24.

Having a strut 14 that is not vertical, as shown in fig.10, can prevent movement of the structure during marching, which is an advantage in terms of longevity.

The struts 14, at least the outermost strut 14, can in some embodiments be connected to a longitudinal structure 34, such as a cantilever, running on an underside of the hull and that is possibly extending outside the side of the hull.

The longitudinal structure 34, which can be a tube, half-tube or similar, can also be used to adjust the angle of attack, of at least the forward wing 22, before take-off based on ballast and cruising speed. Hence, the longitudinal structure 34 is preferable pivotable suspended.

The invention will often be used with high-speed passenger vessels that operate in varying wave heights and lengths, and it may happen that waves are longer than the vessel. For safety reasons, it should therefore be possible for the captain or a computer to override the self-regulation to avoid uncontrolled collisions with water.

Having a “split” wing 22, as shown in fig.5-10, with air intakes, can give more control, stability and height control. Several winglets 24 with air intakes will help to stabilize and give a greater working area in terms of speed. A single wing 22 gets a very strong lift (at higher speeds) and only has two winglets/air intakes to regulate. The center section of a single wing does not help to stabilize the craft and only provides lift.

When the winglet/air system is included in the strut and is part of the supporting structure, there are fewer profiles that have to cut through the water and thus a lower risk of things getting stuck. At the same time, it is an advantage for the captain to know where structures are located around the vessel and fewer parts to follow with cameras.

Claims

1. A hydrofoil vessel (10) comprising several hydrofoils (20), each hydrofoil (20) having a wing (22) arranged to be submerged in water (16), such that the vessel (10) is lifted above water when cruising, said wings (22) being connected to a hull (12) of the vessel (10) by upright struts (14),

wherein each wing (22) comprises an upright winglet (24) connected to the wing (22), said upright winglet (24) having an air intake (28) connected with air outlet apertures (26) on the wing (22).

2. The hydrofoil vessel (10) according to claim 1, wherein the air intake (28) is provided in a tip (24c) of the winglet (24).

3. The hydrofoil vessel (10) according to claim 1, wherein the air outlet apertures (26) are provided on an upper part of the wing (22).

4. The hydrofoil vessel (10) according to claim 1, wherein the air outlet apertures (26) are provided closer to a leading edge (22a) than a trailing edge (22b) of the wing (22).

5. The hydrofoil vessel (10) according to claim 1, wherein the upright winglet (24) is curved backwards, with a leading edge (24a) of the winglet (24) having a convex shape and a trailing edge (24b) of the winglet (24) having a concave shape.

6. The hydrofoil vessel (10) according to claim 1, wherein the wing (22) and the winglet (24) each are hollow, allowing air flow from the air intake (28) in the winglet (24) and to the air outlet apertures (26) in the wing (22).

7. The hydrofoil vessel (10) according to claim 1, wherein the wing (22) and the winglet (24) comprises an air flow channel (30) connecting the air intake (28) and the air outlet apertures (26), allowing air flow from the air intake (28) in the winglet (24) to the air outlet apertures (26) in the wing (22).

8. The hydrofoil vessel (10) according to claim 1, wherein the air outlet apertures (26) are a series of holes or slits in the wing (22).

9. The hydrofoil vessel (10) according to claim 1, wherein the upright winglet (24) is arranged to penetrate a water surface of the water (16), allowing air to be sucked in through the air intake (28) of the winglet (24).

10. The hydrofoil vessel (10) according to claim 1, wherein the upright winglet (24) comprises a nearly planar, straight section joined to an outer end (22c) of the wing (22) through a curved transition section (32) having prescribed curvature limits.

11. The hydrofoil vessel (10) according to claim 1, wherein the wing (22) comprises drainage holes for drainage of water.

12. The hydrofoil vessel (10) according to claim 1, wherein the wing (22) is a horizontal wing, and the winglets (24) are connected to an outer end (22c) of the wing (22).

13. The hydrofoil vessel (10) according to claim 1, wherein said vessel (10) comprises a pair of front horizontal wings (22) with winglets (24) on their ends, and wherein each wing (22) comprises several struts (14) connecting the wing (22) to the vessel (12).

14. The hydrofoil vessel (10) according to claim 1, wherein the winglets (24) are integrated with said struts (14) connecting the wing (22) to the vessel (12).

15. The hydrofoil vessel (10) according to claim 1, wherein all or part of the wing (22) is arranged angled with respect to a horizontal plane.

16. The hydrofoil vessel (10) according to claim 15, wherein the angled wing (22) is inclining outwards, and the winglet (24) on an inner end of the angled wing (22) is higher than the winglet (24) on an outer end of the angled wing (22).

17. The hydrofoil vessel (10) according to claim 1, wherein one or more of said struts (14) is/are arranged angled with respect to a vertical axis.