Wing sail and method

Abstract

1. A wing sail comprising: a first aerofoil having a leading edge at a front of the wing sail and a trailing edge aft of the leading edge; and a second aerofoil having a leading edge and a trailing edge, the leading edge of the second aerofoil being closer to a point of maximum cross-sectional width of the second aerofoil than the trailing edge of the second aerofoil, the wing sail being configured such that the leading edge of the second aerofoil can be positioned aft of the trailing edge of the first aerofoil, the first aerofoil comprising an intake port, an exhaust port, and a flow passage inside the first aerofoil connecting the intake port and the exhaust port, and an airflow from the intake port being guided to the exhaust port by the flow passage.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to a wing sail and a method for operating a wing sail, and more particularly, to a wing sail for a watercraft. In some examples, the watercraft may include a powered watercraft. [Background technology]

[0002] Known wing sails include wing sails that are composed of one aerofoil. Wing sails with multiple aerofoils are also known. Wing sails can be used on marine vessels, for example when transporting goods, to reduce energy requirements during operation. This reduction in energy requirements can result in a reduction in carbon dioxide emissions. Summary of the Invention

[0003] In a first aspect, a wing sail is provided, a first aerofoil having a leading edge aforward of the sail and a trailing edge aft of the leading edge; a second aerofoil having a leading edge and a trailing edge, the leading edge of the second aerofoil being closer to a point of maximum cross-sectional width of the second aerofoil than the trailing edge of the second aerofoil; Equipped with the wing sail is configured such that the leading edge of the second aerofoil may be located aft of the trailing edge of the first aerofoil; the first aerofoil includes an intake port, an exhaust port, and a flow passage in the first aerofoil connecting the intake port and the exhaust port; The airflow from the intake port is guided to the exhaust port by the flow path. A wing sail is provided, characterized in that

[0004] In some examples, the second aerofoil has a first portion that includes the leading edge of the second aerofoil, the first portion being rounded.

[0005] In some examples, the second airfoil is symmetrical about a chord line of the second airfoil.

[0006] In some examples, the chord line comprises a longitudinal axis from the leading edge to the trailing edge.

[0007] In some examples, the airflow from the exhaust outlet is directed out of the exhaust outlet towards the leading edge of the second airfoil.

[0008] In some examples, the exhaust outlet is located at the trailing edge of the first airfoil.

[0009] In some examples, the air intake comprises a port air intake located on a port side of the first aerofoil and a starboard air intake located on a starboard side of the first aerofoil, the first aerofoil configured such that when the wing sail is used on starboard tack, the first aerofoil directs airflow through the port air intake and not through the starboard air intake, and when the wing sail is used on port tack, the first aerofoil configured such that airflow is directed through the starboard air intake and not through the port air intake.

[0010] In some examples, the wing sail is configured such that when the wing sail is used on starboard tack, the second aerofoil is rotated in a starboard direction relative to the first aerofoil such that the exhaust of the first aerofoil directs airflow toward the port leading edge of the second aerofoil, and when the wing sail is used on port tack, the second aerofoil is rotated in a port direction relative to the first aerofoil such that the exhaust of the first aerofoil directs airflow toward the starboard leading edge of the second aerofoil.

[0011] In some examples, the wing sail is configured to draw air into the port intake and not into the starboard intake when the wing sail is used on starboard tack, and to draw air into the starboard intake and not into the port intake when the wing sail is used on port tack.

[0012] In some examples, the wing sail includes a pressure differential generator within the first aerofoil, the pressure differential generator configured to generate a negative internal pressure within the first aerofoil, the negative internal pressure drawing air into the device body through the air intake.

[0013] In some examples, the pressure differential generator comprises one or more fans driven by a motor, or a series of fans driven by a motor and connected on a single fan shaft.

[0014] In some examples, the flow path comprises the pressure differential generator and a vent.

[0015] In some examples, the flow passage is configured to direct flow from the inlet at an initial location along a span of the first aerofoil and direct the flow to the exhaust, where the span of the first aerofoil is the distance from the base of the sail to the tip of the first aerofoil.

[0016] In some examples, the wing sail comprises one or more wing sail modules configured to be vertically stacked on top of one another, each vertically stacked module comprising an intake port, an exhaust port, a pressure differential generator, and a vent.

[0017] In some examples, the flow path includes an internal flow straightener.

[0018] In some examples, the second aerofoil is rotated relative to the first aerofoil to a maximum rotation position to minimize the overall span of the sail, where the sail is folded at the base of the sail to form a stowed configuration.

[0019] In some examples, the base of the wing sail is formed from at least one welded or seamless metal tube.

[0020] In some examples, the wing sail comprises a protective casing for covering the first and second aerofoils in the stowed configuration, the protective casing allowing the wing sail to be raised and / or lowered and capable of covering the wing sail by performing at least one of folding, rotating and rolling along a track when the wing sail is lowered and in the stowed configuration.

[0021] In some examples, the wing sail comprises control software for opening and closing the intakes or directing airflow from one intake to the next; a mechanical control system for opening and closing the intakes.

[0022] In some examples, the wing sail includes a mechanical system actuated to open and close the intake based on movement of the second aerofoil.

[0023] In some examples, the second airfoil includes at least one air intake.

[0024] In some examples, the second aerofoil includes at least one exhaust port.

[0025] In some examples, the first aerofoil includes a plurality of air intakes.

[0026] In some examples, the first aerofoil includes a plurality of exhaust ports.

[0027] In some examples, the first aerofoil includes at least one exhaust outlet located between a portion of the first aerofoil that includes the leading edge and a portion of the first aerofoil that includes the trailing edge.

[0028] In some examples, the second aerofoil includes at least one exhaust outlet located between a portion of the second aerofoil that includes the leading edge and a portion of the second aerofoil that includes the trailing edge.

[0029] In some examples, the wing sail is configured to form a stowed configuration by rotating the second aerofoil relative to the first aerofoil so that the chord lines of each aerofoil are substantially perpendicular to one another, and then rotating both of the aerofoils from the base of the wing sail to a horizontal position.

[0030] In some examples, the wing sail comprises a base structure, the base structure comprising three or more struts supporting a platform, each of the three or more struts having a height between 2 meters and 4 meters, and the first aerofoil and the second aerofoil are positioned above the platform.

[0031] In some examples, the wing sail includes a linear actuator for raising and lowering the wing sail, the linear actuator being located above the platform.

[0032] In some examples, the inlet of the first airfoil element is located within the front quarter of the chord length of the first airfoil element.

[0033] In the second aspect, There is provided a two-element sail comprising a first aerofoil element and a second aerofoil element, the second aerofoil element configured to rotate relative to the first aerofoil element about a first axis of rotation and a second axis of rotation.

[0034] In some examples, the second airfoil element may rotate greater than 180 degrees relative to the first airfoil element.

[0035] In some examples, the first axis of rotation of the second element is located within the first airfoil element and the second axis of rotation is located within the second airfoil element.

[0036] In some examples, the second airfoil element is configured to rotate relative to the first airfoil element to form a cambered shape having a slot between the first and second airfoil elements, and is configured to fold into a close packed arrangement with a reversed orientation of the second airfoil element to minimize the overall chord length and cross-sectional thickness of the sail.

[0037] In some examples, the second airfoil element is coupled to the first airfoil element via one or more independently rotating coupling members.

[0038] In some examples, the independently rotating linkage members comprise two or more bars.

[0039] In some examples, the rods of the independently rotating linkage are connected by a torsion bar such that each rod cannot rotate independently of the other rods.

[0040] In some examples, the one or more connecting members are configured to rotate relative to the first element via two or more rotational bearings, preferably the two or more rotational bearings comprise self-aligning bearings, preferably wherein the self-aligning bearings are coupled to a structure of the first element.

[0041] In some examples, the second component is rotatable relative to one or more coupling members about two or more bearings, preferably self-aligning bearings, which are preferably coupled to the structure of the second component.

[0042] In some examples, one or more linking members are rotatable relative to the first element, and a second airfoil element is rotatable relative to both the first airfoil element and one or more linking members.

[0043] In some examples, the one or more linking members are rotatable relative to the first element and are controlled by a linear actuator, preferably a hydraulic ram rotatably coupled between the linking members and the first airfoil element.

[0044] In some examples, the second aerofoil element is rotatably connected to one or more connecting members that are also connected to the first aerofoil element, where rotation of the second aerofoil element relative to any connecting members is controlled by a linear actuator, preferably a hydraulic pump, rotatably connected to the second aerofoil element and the connecting members, or may be controlled by a rotary actuator.

[0045] In some examples, the first airfoil element portion is thicker than the second airfoil element portion.

[0046] In some examples, the first airfoil element is the same length as the second airfoil element or is shorter than the second airfoil element.

[0047] In some examples, the maximum thickness of the first airfoil element and the maximum thickness of the second airfoil element are within the forward half of the chord length of the elements, and wherein the curvature of each airfoil portion is convex along its entire length and does not include any inflections.

[0048] In some examples the linking member is rotatable about two or more rotation bearings connecting it to the first aerofoil element, preferably the preceding element is provided with bearings both above and below each linking rod, and preferably these bearings should be fixed to the torsion beam between each rod.

[0049] In some examples, the second element may include a top portion and a base portion connected by a torsion beam or torsion structure. The connecting member may be secured to the second element by two or more rotation bearings, preferably connected to the torsion beam of the second element.

[0050] In some instances, the first element is the preceding element.

[0051] In some instances, the second element is a subsequent element.

[0052] In some examples, the sail includes a double hinge mechanism.

[0053] In a third aspect, there is provided a method of minimizing a stowed size of a two-element wing sail, comprising folding a first element over a second element by rotating the first element 180 degrees, each element comprising an aerofoil.

[0054] In some instances, folding occurs across two axes of rotation.

[0055] In some examples, the first axis of rotation is part of a first airfoil element and the second axis of rotation is part of said second airfoil element.

[0056] According to the fourth aspect: a first aerofoil element; and Second aerofoil element A wing sail comprising: the second airfoil element is configured to rotate relative to the first airfoil element about a first axis of rotation from a first position to a second position; in the first position, the first aerofoil element is in front of the second aerofoil element and a chord line of the first aerofoil element is aligned with and parallel to a chord line of the second aerofoil element; In the first position, the first axis of rotation is forward of the second aerofoil element and aft of a leading edge of the first aerofoil element; the second airfoil element is further configured to rotate relative to the first airfoil element about a second axis of rotation from the second position to a third position; In the first position, the second axis of rotation is aft of the first aerofoil element and forward of a trailing edge of the second aerofoil element. A wing sail is provided, characterized in that

[0057] In some examples, in the fourth position, a chord line of the second airfoil element is at an angle of 45 degrees to a chord line of the first airfoil element; The second aerofoil element comprises: rotate in a first rotational direction relative to the first aerofoil element from the fourth position to the first position; rotate relative to the first aerofoil element in the first rotational direction from the first position to the second position; and rotate in the first rotational direction relative to the first aerofoil element from the second position to the third position, where in the third position a chord line of the second aerofoil element forms an angle of approximately 180 degrees with respect to a chord line of the first aerofoil element; It is structured as follows: Thus, the chord length of the second airfoil element is configured to rotate approximately 225 degrees relative to the first airfoil element during rotation from the fourth position to the third position.

[0058] In some examples, when the second aerofoil element is in the first position, the second aerofoil element: rotate about the first axis of rotation from the first position to the fourth position in a second rotational direction opposite to the first rotational direction; rotate about said first axis of rotation in said first rotational direction from said first position to said second position, wherein in said second position a chord line of said second airfoil element forms an angle of approximately 90 degrees with respect to a chord line of said first airfoil element; It is structured as follows: This configures the chord length of the second airfoil element to rotate approximately 135 degrees relative to the first airfoil element during rotation from the fourth position to the second position.

[0059] In some examples, when the second aerofoil element rotates from the first position in the first rotational direction or the second rotational direction, a slot is formed between the first aerofoil element and the second aerofoil element, the slot comprising a cavity that allows a flow of energy from a pressure side of the sail to a suction side of the sail when the sail encounters a wind stream.

[0060] In some examples, the second airfoil element is configured to rotate about the second axis of rotation in the first rotational direction beyond the second position to move the second airfoil element to the third position.

[0061] In some examples, the wing sail comprises: a first ram connecting the first airfoil element and the second airfoil element, the ram configured to limit rotation of the second airfoil element about the first axis of rotation in response to an actuation range of the first ram; at least one of a second ram and a rotary actuator configured to rotate the second airfoil element about the second axis of rotation within an operating range of the first ram; and Equipped with.

[0062] In some examples, when the second aerofoil element is in the second position, a chord line of the first aerofoil element and a chord line of the second aerofoil element are approximately perpendicular.

[0063] In some examples, when the second aerofoil element is in the third position, a total chord length of the sail is minimized, where the total chord length comprises a length of chord length from the leading edge to the trailing edge of the sail, and the total chord length of the sail is the sum of the chord lengths of the first and second elements.

[0064] In some examples, the sail includes a double hinge mechanism, the double hinge mechanism providing the first axis of rotation and the second axis of rotation.

[0065] In some examples, the sail comprises a base coupled to the first aerofoil element, the base configured to couple the sail to a marine vessel.

[0066] In some examples, the wing sail comprises a coupling member for coupling the second aerofoil element and the first aerofoil element via one or more independently rotating coupling members, the coupling members comprising one or more rods connecting the first aerofoil element and the second aerofoil element, and a torsion girder connecting two or more of the rods such that each rod cannot rotate independently relative to any one or more of the rods.

[0067] In some examples, the coupling member is configured to rotate relative to the first airfoil element about two or more rotation bearings.

[0068] In some examples, the wing sail comprises a torsion spar configured to connect each of the rods, and for each of two or more of the rods, one of two or more of the rotation bearings is connected to the torsion spar above the rod and one of two or more of the rotation bearings is connected to the torsion spar below the rod.

[0069] In some examples, the second element is rotatable relative to the coupling member about two or more additional bearings.

[0070] In some examples, at least one of the two or more rotation bearings and the two or more further bearings comprises a self-aligning bearing.

[0071] In some examples, the connecting member is rotatable relative to the first aerofoil element and the second aerofoil element is rotatable relative to both the first aerofoil element and the connecting member.

[0072] In some examples, the wing sail comprises a first linear actuator for controlling rotation of the linkage member relative to the first aerofoil element.

[0073] In some examples, the wing sail comprises a second linear actuator for controlling rotation of the second aerofoil element relative to the linkage member.

[0074] In some examples, at least one of the first linear actuator and the second linear actuator comprises a hydraulic ram.

[0075] In some examples, the wing sail comprises a hydraulic motor for controlling rotation of the second aerofoil element relative to the linkage member.

[0076] In some examples, the first airfoil element portion is thicker than the second airfoil element portion.

[0077] In some examples, the first airfoil element is the same length as the second airfoil element or is shorter than the second airfoil element.

[0078] In some examples, the maximum thickness of the first airfoil element is within the forward half of the chord length of the first airfoil element and the maximum thickness of the second airfoil element is within the forward half of the chord length of the second airfoil element.

[0079] In some examples, the curvature of the leading edge of each airfoil element is convex.

[0080] In some examples, pressure is generated in cavities within the first and / or second airfoil elements and a high pressure airflow is directed to the suction side of the airfoil, where the high pressure airflow is distributed to one or more flow passages within each airfoil element.

[0081] In some examples, suction is generated within a cavity of the second airfoil element, and air inlet holes in a surface of the element allow air to be drawn from an external boundary layer into the internal cavity of the second airfoil element.

[0082] According to the fifth aspect, rotating a second aerofoil element relative to a first aerofoil element about a first axis of rotation from a first position to a second position, where in the first position, the first aerofoil element is forward of the second aerofoil element and a chord line of the first aerofoil element is aligned with and parallel to a chord line of the second aerofoil element and where in the first position, the first axis of rotation is forward of the second aerofoil element and aft of a leading edge of the first aerofoil element; and rotating the second aerofoil element relative to the first aerofoil element about a second axis of rotation from the second position to a third position, where in the first position the second axis of rotation is located aft of the first aerofoil element and forward of a trailing edge of the second aerofoil element; A method is provided that includes:

[0083] According to a sixth aspect, there is provided a method comprising using a wing sail according to any of the first to fourth aspects or examples thereof described above.

[0084] According to a seventh aspect, there is provided a method of manufacturing a wing sail according to any of the first to fourth aspects or examples thereof described above.

[0085] According to an eighth aspect, there is provided a base structure for a wind propulsion system, the base structure comprising a platform and three or more columns supporting the platform, each of the three or more columns having a height between 2 meters and 4 meters, and the wind propulsion system being located above the platform.

[0086] According to some examples, the base structure includes a linear actuator for raising and lowering the wind propulsion system, the linear actuator being located above the platform. [Brief description of the drawings]

[0087] [Figure 1] FIG. [Diagram 2] A horizontal cross-section of a wing sail. [Diagram 3] FIG. 2 is a plan view of a wing sail in a feathered arrangement. [Figure 4] This is a plan view of the wing sail in a cambered configuration on port tack. [Diagram 5] This is a plan view of the wing sail in a cambered arrangement on starboard tack. [Figure 6] This is an inside view of the wing sail in a cambered arrangement on starboard tack. [Figure 7] This is an inside view of the wing sail in a cambered configuration on port tack. [Figure 8] FIG. 2 is a vertical cross-sectional view of a wing sail. [Figure 9] FIG. 2 is a vertical cross-sectional view of a wing sail. [Figure 10] FIG. 2 is a vertical cross-sectional view of a wing sail. [Figure 11] FIG. 2 is an external view of a modular wing sail. [Figure 12] A vertical cross section of a modular wing sail. [Figure 13] FIG. 2 is a plan view of the wing sail in a cambered configuration. [Figure 14A] This is a plan view of the wing sail in the stowed and protected configuration. [Figure 14B] FIG. 1 is a plan view of the wing sail in a stowed, unprotected configuration. [Figure 15] This is a view of the port side of the wing sail. [Figure 16] This is a view of the starboard side of the wing sail. [Figure 17] FIG. 2 is a cross-sectional view of the wing sail showing the rotation point of the wing sail. [Figure 18] FIG. 1 shows cross-sections of three configurations of wing sails. [Figure 19] FIG. 2 is a cross-sectional view of a wing sail in port and starboard tack positions. [Figure 20] FIG. 2 shows an enlarged portion of the sail tip. [Figure 21] FIG. 2 shows an enlarged portion of the base of the sail. [Figure 22] FIG. 1 shows five configurations of wing sails. [Diagram 23] FIG. 2 shows a connecting member of the wing sail used to connect the leading edge element and the trailing edge element of the wing sail. [Figure 24] FIG. 2 shows the upright and stowed configurations of the wing sail. [Diagram 25] FIG. 2 shows the wing sail with the aerodynamic fairing removed. [Figure 26] FIG. 2 shows the wing sail with the aerodynamic fairing removed. [Figure 27] FIG. 1 shows a wing sail with multiple exhaust ports on the forward aerofoil. [Figure 28] FIG. 1 shows a wing sail with multiple exhaust ports on the forward and aft aerofoils. [Figure 29a] FIG. 1 shows a wing sail in an upright position. [Figure 29b] FIG. 13 shows the wing sail in a stowed configuration. [Diagram 30] FIG. 1 shows the wing sail in a stowed configuration relative to the vessel. [Figure 31a] FIG. 2 shows the base structure of a wind propulsion device. [Figure 31b] FIG. 2 shows the base structure of a wind propulsion device. [Figure 31c] FIG. 2 shows the base structure of a wind propulsion device. [Figure 32a] FIG. 2 is a diagram showing the airflow around a wing sail not incorporating a suction mechanism at a first angle of attack. [Figure 32b] FIG. 2 illustrates the airflow around a sail having a suction mechanism incorporated therein and an air inlet aft of the first aerofoil element at a first angle of attack. [Fig. 32c] FIG. 2 is a diagram showing the airflow around a wing sail not incorporating a suction mechanism at a second angle of attack. [Fig. 32d] FIG. 13 illustrates the airflow around a sail having a suction mechanism incorporated therein and an air inlet forward of the first aerofoil element at a second angle of attack. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0088] In accordance with some examples, a wing sail and a method of operating a wing sail are described. The wing sail may be used on a watercraft. The watercraft may include, for example, at least one of a marine vessel, a boat, and a ship. In some examples, the watercraft may be a powered watercraft. In some examples, the watercraft may be a commercial vessel, such as a bulk carrier or a product tanker.

[0089] In some examples, the wing sail may be disposed on a surface of the watercraft, for example, on the deck of the watercraft.

[0090] A typical wing sail may be rigid. The wing sail may be attached to a marine vessel (e.g., a powerboat, a ship, etc.). The wing sail may be considered to be a variable camber aerodynamic structure that is attached to a vessel (e.g., a marine vessel).

[0091] A typical marine vessel on which these units are fitted may be 150m to 360m in length, although smaller or larger vessels may be fitted. In some instances, the wing sails are used to generate thrust that is transferred to the vessel to move the vessel forward and to reduce the thrust that needs to be generated from the vessel's engines. Depending on the type of vessel, route, number of wing sail units, and other factors, in some instances this can reduce the power that needs to be generated from the main engines, reducing fuel consumption and carbon emissions by approximately 20-30%.

[0092] Some example wing sails described in this disclosure may comprise at least two wing sail elements. Each of the wing sail elements may comprise a leading edge and a trailing edge. Each of the wing sail elements may have an aerodynamic shape (e.g., a shape similar to the shape of the aerofoil element 103 or the aerofoil element 105 shown in FIG. 1). The aerodynamic shape of each wing sail element may generate lift when airflow passes over a surface of the respective wing sail element. Each wing sail element may comprise an aerofoil.

[0093] In some examples, the leading edge of each aerofoil is closer to the widest portion of the aerofoil while the trailing edge of each aerofoil is further away from the widest portion of the aerofoil, although other example shapes may be used for the aerofoils.

[0094] The sail may incorporate boundary layer flow control. The boundary layer of a sail may be thought of as comprising a thin layer of air flowing over its surface. In some examples, the flow of air in the boundary layer is controlled to prevent separation of the airflow over the sail and reduce the tendency of the sail to stall. This may increase the achievable lift of the sail.

[0095] FIG. 1 shows a perspective view of an example wing sail 101. The wing sail 101 is a two-element wing sail having a first aerofoil 103 and a second aerofoil 105. One of the two elements of the wing sail 101 is the first aerofoil 103, and the other of the two elements of the wing sail 101 is the second aerofoil 105. The first aerofoil 103 comprises a leading edge 103a, a trailing edge 103b, and a portion 103c having a maximum cross-sectional width. As shown in the example of FIG. 1, the leading edge 103a is closer to the portion 103c having a maximum cross-sectional width than the trailing edge 103b. The portion of the aerofoil 103 including the leading edge 103a is rounded, and the portion of the aerofoil 103 including the trailing edge 103b is pointed (or may have a rounded shape with a radius of curvature smaller than the radius of curvature of the leading edge). In some examples, the portion of the aerofoil 103 that includes the leading edge 103a has a wider cross-sectional width than the portion of the aerofoil 103 that includes the trailing edge 103b. However, it is envisioned that other shapes may be used for the first aerofoil 103.

[0096] The second aerofoil 105 comprises a leading edge 105a, a trailing edge 105b and a portion having a maximum cross-sectional width 105c. The leading edge 105a is closer to the portion having a maximum cross-sectional width 105c than the trailing edge 105b. The portion of the aerofoil 105 including the leading edge 105a is rounded and the portion of the aerofoil 105 including the trailing edge 105b is pointed. However, it is envisaged that other shapes may be used for the first aerofoil 103.

[0097] The second airfoil 105 may be symmetrical about its chord line, for example as shown in Figures 1 and 2 .

[0098] The first airfoil 103 may be symmetrical about a chord line of the second airfoil 105, for example as shown in Figures 1 and 2.

[0099] The chord line of an airfoil may be considered as the longitudinal axis of the airfoil from the leading edge to the trailing edge.

[0100] The leading edge 103a may be considered to be the nominal "lead" of the wing sail 101. The trailing edge 103b is aft of the leading edge 103a. In the feathered arrangement of Figure 1, the second aerofoil 105 is aft of the first aerofoil 103, and the leading edge 105a of the second aerofoil 105 is forward of the trailing edge 105b of the second aerofoil 105.

[0101] The aerofoils 103 and 105 have a "teardrop" shape, although other aerodynamic shapes may be used. In general, an aerofoil such as aerofoil 103 or 105 may have any shape that produces an aerodynamic effect perpendicular to the direction of the airflow passing over it (lift) while offering little resistance in the direction of the airflow (drag).

[0102] The wing sail device 101 may rotate about its base to change the angle of attack with respect to the apparent wind direction. In this way, the wing sail device 101 may optimize the lift it generates. The lift is generated by the pressure difference between the two sides of the wing sail 101, creating a high pressure side and a low pressure side due to the difference in the speed of the air flowing on either side of the wing sail device 101. The apparent wind is the wind experienced by a moving vessel. The apparent wind is a combination of the wind experienced by the forward motion of the vessel and the prevailing wind. The combination of these two vectors creates the "apparent wind". The apparent wind may have a different angle and wind speed than the wind experienced by the forward motion of the vessel and the prevailing wind.

[0103] The second aerofoil 105 is rotatable relative to the first aerofoil 103, allowing the camber of the device 101 to be adjusted and reversed.

[0104] When the sail device 101 is on port tack (when the apparent wind is on the port side of the device 101 ), the second airfoil 105 may be rotated to port relative to the first airfoil 103 .

[0105] When the sail device 101 is on starboard tack (when the apparent wind is on the starboard side of the device 101 ), the second aerofoil 105 is rotated to starboard relative to the first aerofoil 103 .

[0106] For example, as seen in Figures 4, 5, 6, 7, 13, 14A and 14B, when the second aerofoil 105 is rotated relative to the first aerofoil 103, the chord lines of the first aerofoil 103 and the second aerofoil 105 are not parallel. This allows the sail device 103 to be in a cambered configuration. This can be achieved by rotating the second aerofoil 105 relative to the first aerofoil 103.

[0107] In the cambered configuration of the device 101, a slot is formed between the first 103 and second 105 aerofoils. The slot allows high pressure airflow to flow from the high pressure side to the low pressure side surface. This reinvigorates the airflow over the second aerofoil, allowing the airflow to stay attached at extreme angles of attack, avoiding sail stall and achieving a higher lift coefficient.

[0108] In some examples, the wing sail 101 may be fitted with a pressure differential generator 111 (e.g., as shown in FIG. 1 ). The pressure differential generator 111 may be used to control the airflow around the device 101. This controlled airflow allows the device to be used at higher angles of attack and higher camber angles without stalling, which may significantly increase the achievable lift coefficient for the wing sail 101. In some examples, the pressure differential generator may include one or more rotating blades (e.g., fan blades), which may be coupled by a shaft.

[0109] To control the airflow around the wing sail 101, the air inlet 107 draws air into the interior of the wing sail 101. The wing sail 101 may also include an exhaust outlet 109. In some examples, the exhaust outlet 109 may be located at the trailing edge 103b of the first aerofoil 103, as shown in Figures 1 and 2 for example. However, it will be appreciated that in other examples the exhaust outlet 109 may be located at other locations on the first aerofoil 103.

[0110] The air drawn in at the inlet 107 is directed through an internal passage 119 into the interior of the airfoil 103. The internal passage 119 connects the inlet 107 and the outlet 109. The outlet 109 emits an airflow from the airfoil 103. This airflow may constitute a focused air jet. This airflow may be directed onto the surface of the second airfoil element 103. In the example of Figures 1 and 2, the airflow may be emitted from the outlet 109 at the trailing edge 103b of the first airfoil 103 towards and over the leading edge 105a of the airfoil 105.

[0111] The pressure differential generator 111 may be powered by one or more motors. These motors may include, for example, hydraulic or electric motors. When actuated, the pressure differential generator 111 may create an area of ​​low pressure at the inlet 107 of the flow path 119 such that air is drawn in, and an area of ​​high pressure at the outlet 109 of the flow path 119 such that air is forced out the outlet 109.

[0112] A pressure differential generator 111 may be configured to create a negative internal pressure within the first airfoil, where the negative internal pressure draws air into the body of the first airfoil through the air inlet 107.

[0113] The pressure differential generator 111 may, for example, comprise a fan driven by a motor, or a series of fans driven by a motor and connected by a single fan shaft.

[0114] In some instances, the airflow hits the leading edge of the first aerofoil element 103 and flows around the surface (both sides). As the airflow passes over the low pressure surface, the laminar boundary layer begins to transition to turbulent, at which point if the angle of attack of the device 101 becomes large, the airflow will separate and the device 101 will stall.

[0115] To allow the apparatus 101 to operate at higher angles of attack (and therefore generate more lift), in some examples the air passing over the surface of the forward aerofoil 103 is sucked inward at a location near the aft end of the forward aerofoil 103. This removes some of the turbulent boundary layer and keeps the airflow attached at higher angles of attack, thereby allowing the apparatus 101 to generate more thrust.

[0116] The second aerofoil 105 is located aft of the first aerofoil 103 and when the aerofoil 105 is in a cambered configuration, a slot is created between the first aerofoil 103 and the second aerofoil 105. This slot allows a high pressure jet of air from the high pressure side (113 in Figure 6, 115 in Figure 7) to the low pressure side (115 in Figure 6, 113 in Figure 7) and allows the airflow to again remain attached at a higher angle of attack and camber angle. This in turn means that the device produces more thrust to the vessel.

[0117] An exhaust port 109 may be located at the trailing edge of the first aerofoil element 103 to further enhance the high pressure jet of air through the slot, thereby maximizing the angle of attack achievable before the sail 101 stalls and maximizing the thrust produced while reducing drag.

[0118] Thus, by using at least one inlet 103 and at least one outlet 109 on the first aerofoil 103, a higher angle of attack of the device 101 can be achieved without stalling. Additionally or alternatively, by cambering the second aerofoil 105 relative to the first aerofoil 103, a higher angle of attack of the device 101 can be achieved without stalling.

[0119] FIG. 2 is a cross-sectional plan view of the wing sail 101. As shown in FIG. 2, the air inlets 107 include two air inlets 107s and 107p on both sides 113 and 115 (port side 113 and starboard side 115, respectively) of the first aerofoil 103. In the example of FIG. 2, the air inlets 107 are located towards the trailing edge 103b of the first aerofoil 103. Each air inlet 107 may have a vertical strip (or multiple vertical strips) that allows air to enter the aerofoil 103. The vertical strips may have gaps in the device that allow air to enter. In other examples, the air inlets may have cut openings (such as circular holes or holes of other shapes) or a surface with other porous materials that allows air to enter the first aerofoil 103. This surface, with its cut out shape or porous material, controls the speed and volume of air entering the sail to optimize the aerodynamics of the device, and has the added benefit of preventing debris from being sucked into the interior of the aerofoil 103.

[0120] The inlet 107 draws the unsteady flow near the surface of the device 101 into the body of the first aerofoil 103, allowing the flow to remain attached at a larger angle of attack, thereby producing a larger lift coefficient.

[0121] In the example of Fig. 2, a partition 112 is provided between the body of the aerofoil 103 and the pressure differential generator 111. In this way, the generated airflow affects the internal airflow at the trailing edge 103b of the device, but the airflow generated from the pressure differential generator 111 can be prevented from affecting the internal airflow within the body of the aerofoil 103 (i.e., within the body located at the leading edge 103a).

[0122] 3-7 show an example of a wing sail 101 under the influence of wind 130. Although a wing sail 101 is shown in the figures, the same principles may be applied to the wing sails 401, 621, or other wing sails described in this disclosure.

[0123] When the wind direction 130 is directed directly at the leading edge of the aerofoil 103 forward of the aerofoil sail 101 (i.e., when the wind direction is directed between the port side 113 and starboard side 115 of the aerofoil sail), the aerofoil sail 101 may be arranged in a feathered configuration, in which the chord lines of the aerofoils 103 and 105 are aligned and parallel to one another.

[0124] 4 shows an example of the wing sail 101 on port tack. When the wing sail 101 is operating on port tack, i.e., when the apparent wind 130 is across the port side of the vessel to which the wing sail 101 is attached, the angle of attack of the wing sail 101 may be configured such that the apparent wind 130 is directed at the port leading edge of the wing sail 101. In the port configuration, with the second aerofoil 105 rotated to the port side 113 relative to the first aerofoil 103, the wing sail 101 may be in a cambered configuration. In the port configuration, the starboard air inlet 107s is open and the port air inlet 107p is closed. The exhaust port 109 of the first aerofoil 103 directs the airflow onto the starboard leading edge of the second aerofoil 105 , thereby reinvigorating the airflow at this point and increasing the stall angle of the device 101 .

[0125] FIG. 5 shows an example of the situation where the wing sail 101 is on starboard tack. When the wing sail 101 is operating on starboard tack, i.e. when the apparent wind 130 crosses the starboard side of the vessel on which the wing sail 101 is installed, the angle of attack of the wing sail 101 can be configured such that the apparent wind 130 is directed to the starboard leading edge of the wing sail 101. In the port configuration where the second aerofoil 105 is rotated to the starboard side relative to the first aerofoil 103, the wing sail 101 can be in a cambered configuration. In the starboard configuration, the starboard intake 107s is closed and the port intake 107p is open. The exhaust 109 of the first aerofoil 103 directs the airflow to the port leading edge of the second aerofoil 105, thereby reinvigorating the airflow at this point and increasing the stall angle of the device 101.

[0126] FIG. 6 illustrates an example of how starboard inlet 107s may be closed while on starboard tack, while port inlet 107p remains open. Inner wall 129 may be positioned to close starboard inlet 107s while port inlet 107p remains open. Inner wall 129 may be rotated about a rotation point 127. This rotation may be performed using a motor, such as an electric motor or a hydraulic motor. This rotation may be performed automatically based on a computer system of the wing sail 101 detecting whether the wing sail 101 is on port or starboard tack. In some examples, this rotation may be performed based on a user input to the computer system. In other examples, this rotation is performed based on manual manipulation by a user of the wing sail 101. When the wing sail 101 is used on starboard tack, the wing sail 101 may draw air into the port intake 107p and not into the starboard intake 107s.

[0127] FIG. 7 illustrates an example of how starboard inlet 107s may be opened while on port tack, while port inlet 107p remains closed. The wing sail 101 may be manipulated to transition between the configurations shown in FIG. 6 and FIG. 7. The inner wall 129 may be positioned to close port inlet 107s while port inlet 107p remains closed. The inner wall 129 may be rotated about a rotation point 127. This rotation may be performed using a motor, such as an electric motor or a hydraulic motor. This rotation may be performed automatically based on a computer system of the wing sail 101 detecting whether the wing sail 101 is on port or starboard tack. In some examples, this rotation may be performed based on a user input to the computer system. In other examples, this rotation is performed based on manual manipulation by a user of the wing sail 101. When the wing sail 101 is used on port tack, the wing sail 101 may not draw air into the port intake 107p, but may draw air into the starboard intake 107s.

[0128] The computer system described in this disclosure may be configured to include at least one processor and associated memory and may be used to execute control software for opening and closing at least one air inlet of the wing sail 101.

[0129] FIG. 8 shows a cross section through the center of the wing sail 101 in an arrangement where the chord lines of the aerofoil 103 and the aerofoil 105 are aligned and parallel. FIG. 10 also shows a side view of the cross section of the wing sail 101. As seen in FIG. 8 and FIG. 10, an internal vent 119 (channel) connects the inlet 107 and the outlet 109. In the example of FIG. 3, the outlet is located at the trailing edge of the aerofoil 103. The channel 119 may be configured to direct the flow from the inlet 107 at an initial position along the span of the wing sail 101 and direct the flow to the outlet 109. Here, the span of the wing sail 101 is the distance from the base of the wing sail 101 to the tip of the wing sail 101.

[0130] The vent volume is smaller at the exhaust 109 than at the inlet 107. The air from the pressure differential generator 111 is focused as it moves towards the exhaust 109 by the reduction in the volume of the internal vent 119 from the pressure differential generator 111 towards the exhaust 109. This provides a more concentrated energized flow that is directed towards the second aerofoil. The air is discharged from the exhaust 109 as a concentrated air flow that flows towards the surface of the second aerofoil element 105. In some examples, the second aerofoil 105 may be in a cambered configuration. The concentrated air flow from the exhaust 109 reenergizes the boundary layer and allows the air flow to remain attached at larger camber angles and angles of attack, thereby increasing the stall angle and also increasing the maximum achievable lift coefficient of the sail 101.

[0131] In the example of Figures 8, 9 and 10, the flow passage 119 is inclined so that the flow passage is longer along the vertical axis 132 of the wing sail 101 at the exhaust 109 than at the inlet 107. The vertical axis 132 is shown in Figure 10. As will be further explained with reference to Figures 11 and 12, this inclined flow passage shape is useful when wing sail modules such as the wing sail 101 are stacked on top of each other. In this example, wing sail modules having the flow passage shape (shape of 117) can be stacked on top of each other to create a larger wing sail that includes multiple modules. In this case, airflow is directed from the inlet of the higher module part through a pressure differential generator to the outlet of the lower module part. However, other flow passage shapes can be used to achieve other results. For example, if the flow path is tilted such that the flow path is longer along the vertical axis 132 of the wing sail 101 at the inlet 107 than at the exhaust 109, the airflow will be directed from the inlet of a lower module portion, through a pressure differential generator, to the exhaust of a higher module portion. Additionally, a non-tilted (substantially straight or linear along the vertical axis 132) flow path may be used to direct the airflow from the inlet of a module portion, through a pressure differential generator, to the exhaust of the same module portion.

[0132] If the wing sail is constructed as a single unit (e.g., wing sail 101 of FIG. 1), any of the three flowpath shapes described above may be used. In some examples, a non-sloped flowpath may be used for the single unit, such that the internal airflow goes from an inlet at one height, through a pressure differential generator, and out an exhaust at the same height.

[0133] In some examples, a modular wing sail (eg, wing sail 621) may be made up of two or more internal modules covered by an outer case.

[0134] In some examples, the wing sail 101 may have similar dimensions to 101, being greater in height than in length.

[0135] FIG. 9 shows a cross section through the center of an exemplary portion of the wing sail 401 in a chord-aligned and parallel arrangement of the forward and aft aerofoils of the wing sail 401. The wing sail 401 may have a similar structure to the wing sail 101. The wing sail 401 further includes at least one airflow straightener 425 disposed at the forward aerofoil outlet 405 of the wing sail 401 to allow airflow to exit the outlet in a controlled manner and maximize the aerodynamic benefits of the controlled airflow. Additionally or alternatively, at least one airflow straightener may be disposed at the forward aerofoil inlet. Furthermore, instead of or in addition to at least one airflow straightener disposed at the forward aerofoil inlet or outlet of the wing sail 401, at least one airflow straightener may be disposed between the inlet and outlet of the wing sail 401. The airflow straightener may comprise at least one wall disposed along the air inlet, the air outlet, or a flow path connecting the air inlet and the air outlet.

[0136] 11, in some examples, wing sail modules, such as wing sail modules 601a and 601x, may be stacked on top of one another to form wing sail 621. Each wing sail module 601a, 601x, etc. may have a structure similar to wing sail 101, wing sail 401, or other wing sails described above.

[0137] Each wing sail module 601 may include an air inlet 607, an air outlet, and a pressure differential generator. Each wing sail module 601 may be configured to be stacked on top of one another.

[0138] Figure 11 is an external view of wing sail 621 comprising wing sail modules 601a and 601x. In some examples, additional modules may be included as shown in Figure 11. Figure 12 shows an internal cross section of wing sail 621 comprising wing sail modules 601a and 601x.

[0139] The wing sail 621 comprises at least two wing sail modules 601a and 601x, each of which comprises an inlet 607a and 607x aligned with each other. The wing sail module 601a comprises an air vent 619a. The wing sail module 601x comprises an air vent 619x. In the wing sail 621, the air vents (such as air vents 619a and 619x) of each of the wing sail modules 601a and 601x may direct the internal airflow from the pressure flow generator to the exhaust of each wing sail module 601a and 601x. Each wing sail module (e.g., wing sail modules 601a and 601x) may comprise its own pressure differential generator. The air vents of each wing sail module may direct the internal airflow from the internal pressure differential generator to the exhaust.

[0140] The wing sail 621 may comprise at least one fan at the trailing edge of the forward aerofoil (similar to the aerofoil 103 of the wing sail 101) of each wing sail module 601a, 601x etc. Each fan may be driven by one or more hydraulic or electric motors. Each fan may be connected by a central shaft constituted by the shaft modules of each wing sail module. In the example of Figure 11, the shaft module 617a of the wing sail module 601a is connected to the shaft module 617x of the wing sail module 601x.

[0141] The wing sail module 601x is located at the top of the wing sail 621. The wing sail module 601a is a wing sail module other than the top wing sail module 601x. The flow paths of each module (e.g., flow paths 617x and 617a) are inclined such that each flow path is longer along the vertical axis (where both axes are similar to the axis 132 of the wing sail 101) of each wing sail module 617a and 617x at the outlet of each wing sail module than at the inlet of each wing sail module 607a and 607x. Because each wing sail module has this flow path shape, the airflow flows from the inlet of the higher module section, through the pressure differential generator, to the outlet of the lower module section. For example, the airflow from the inlet 607x is directed to the outlet of the wing sail module directly below the wing sail module 601x. The airflow from the air inlet of the wing sail module directly above wing sail module 601a is directed to the exhaust port of wing sail module 601a. ​​The airflow from air inlet 607a is directed to the exhaust port of the wing sail module directly below wing sail module 601a. ​​Because wing sail module 601x is at the top of wing sail 621, the airflow is sucked in from above wing sail module 601x and directed to the exhaust port of wing sail module 601x.

[0142] As discussed above in relation to Figures 8, 9 and 10, other flowpath geometries may be used to provide different airflows between modules of a modular wing sail. For example, if the flowpath is inclined such that the flowpath is longer along the vertical axis of the wing sail module at the inlet than at the outlet, the airflow will be directed from the inlet of the lower module section, through the pressure differential generator, to the outlet of the upper module section. In this case, the bottom wing sail module will draw air from below the modular wing sail. Additionally, non-inclined (substantially straight or linear along the vertical axis of the wing sail module) flowpaths may be used to direct airflow from the inlet of a module section, through the pressure differential generator, to the outlet of the same module section.

[0143] In another embodiment of the invention, the sail may have an air inlet as shown in the previous example and an outlet at the base or top of the sail, where air is drawn into the air inlet by a fan located at the base or top outlet of the sail and the internal airflow is directed up or down across the span of the sail.

[0144] The wing sail devices described herein may include one or more internal structural members. For example, the wing sail or wing sail module may include, for example, structural steel girders, aluminum girders, and / or composite girders. The wing sail may also include lateral and / or longitudinal stiffeners constructed of similar materials. In such an example, the skin may create the exterior aerodynamic shape of the device and may be constructed of, for example, at least one of steel, aluminum, and composite. The interior ventilation openings (channels) may be constructed of, for example, at least one of steel, aluminum, and composite.

[0145] In some examples, the device may have a monocoque structure with a thicker outer skin, for example, constructed of steel, aluminum, and / or composite material, which may bear the majority of the structural load of the device.

[0146] The device may rotate the angle of attack relative to the apparent wind using either a slewing gear bearing or a bearing with a rack and pinion system, where the bearing may be connected to the bottom of the wing sail and the wing sail to its base (connected to the vessel). The bearing may be located under the first aerofoil 103 in a position that allows the wing sail 101 to naturally tilt into a weathervane configuration in the event of a failure of all systems. In the natural weathervane configuration, the wing sail 101 may tilt into the wind in a configuration similar to that shown in FIG. 3.

[0147] In the above example, only one air inlet on the forward airfoil is described, comprising a starboard air inlet and a corresponding port air inlet. In a further example, the device may comprise multiple air inlets, each comprising one starboard air inlet and one port air inlet on the forward airfoil.

[0148] In the above examples only one exhaust outlet on the forward aerofoil is described, in further examples the device may comprise multiple exhaust outlets on the forward aerofoil.

[0149] In a further example, the wing sail may include at least one intake port on the second aerofoil.In a further example, the wing sail may include at least one exhaust port on the second aerofoil.

[0150] In some examples, the wing sail 101 may be stored and protected by a protective cover 123. This process is shown in Figures 14A and 14B. In Figure 14A, the wing sail 101 is in a stored configuration and is protected by the protective cover 123. In Figure 14B, the protective cover 123 is open, allowing the wing sail 101 to be adjusted in various directions. The protective cover 123 may be constructed of steel or other material and can be folded or rotated over the device to protect the device from situations that could cause crane grabs, falling objects such as iron ore, or other impacts that could damage the wing.

[0151] In some examples, the wing sails described herein may include base and end plates that may improve the aerodynamic performance of the device by reducing vortex shedding as a result of lift generation.

[0152] In some examples, the sails described herein may include base and end plates and may also include enclosures along the span of the device, which may help direct flow across the surface of the device and reduce vortex shedding and associated losses.

[0153] A two-element wing sail consisting of two aerofoils is described in more detail below with reference to Figures 15 to 26. A method for moving the two aerofoils relative to each other is described. It should be noted that the aerofoils described with reference to Figures 15 to 26 below may include inlets and outlets for controlling airflow as described above. Any of the features described with reference to Figures 15 to 26 below may be incorporated into any of the wing sails described above, for example wing sails 101, 401 and 623.

[0154] Figures 15 and 16 show the wing sail 1. Figure 15 is a view from the port side, and Figure 16 is a view from the starboard side. The wing sail 701 is composed of a first aerofoil element 703 and a second aerofoil element 705, where the first aerofoil element 703 is the leading element and the second aerofoil element 705 is the trailing element. The second aerofoil element 705 can rotate with respect to the first aerofoil element 703 and can form a cambered shape (as shown in Figure 17) which is advantageous for generating lift. When the second aerofoil element 705 rotates with respect to the first aerofoil element 703, a "slot" 704 is formed between the first aerofoil element 703 and the second aerofoil element 705. This slot 704 allows high energy flow from the pressure side to flow to the suction side and also allows the flow to remain attached at higher angles of attack, which is advantageous for generating lift. The second aerofoil element 7053 may be of the same chord length as the first aerofoil element 703, but may be shorter or longer in some cases. The thickness of the first aerofoil element 703 may be greater than the second aerofoil element 705 to increase the moment of area of ​​the internal structure and optimize the aerodynamic performance of the device. The shape of the aerofoil section comprising the first aerofoil element 703 and the second aerofoil element 705 has a maximum thickness in the front half of the aerofoil section. The curvature of each aerofoil section comprising the aerofoil elements 703 and 705 is convex along the entire length of each aerofoil section, and the curvature remains positive along the entire length of each aerofoil section and does not include any inflections.

[0155] The first aerofoil element 703 is directly connected to the base 706 of the wing sail 701. The base 706 connects the wing sail 701 to an associated marine vessel. The second aerofoil element 705 is connected to the base 706 of the wing sail 701 via a connection to the first aerofoil element 705.

[0156] Figure 18 illustrates several different exemplary configurations of the wing sail 701. As shown in Figure 18, the wing sail 701 can transition between a feathered configuration 755, in which the cross-sectional centerlines 758 of both aerofoil elements 703 and 705 are aligned, and a cambered configuration 756, in which the second aerofoil element 705 is rotated relative to the first aerofoil element 702. The wing sail 701 can also be articulated such that the first aerofoil element 703 and the second aerofoil element 705 form a close-packed configuration 757.

[0157] The wing sail 701 can reverse its camber in both directions, allowing the wing sail to generate lift 759 at wind angles 760 coming from both its right and left side, as shown in Figure 19. The wing sail 701 can also rotate 360 ​​degrees around the base 706 about the angle of attack axis 748, allowing the angle of attack of the wing sail 701 to be adjusted and optimized depending on the wind direction relative to the marine vessel. By adjusting both the angle of attack of the wing sail 701 and the camber of the wing sail 701, the aerodynamic flow around the wing sail 701 can be optimized to generate a desired amount of thrust.

[0158] To allow the wing sail 701 to be stowed with minimal interference during port operations, the wing sail 701 may be configured to minimize its height in the stowed state above the deck of the marine vessel and to avoid any protrusion of the first aerofoil element 703 and the second aerofoil element 705. To do this, the wing sail 701 forms a packed arrangement as shown in arrangement 757 in Figure 18 and is folded from a vertical position to a horizontal position, minimizing the overall height of the wing sail 701. This process is explained in the following paragraphs.

[0159] The second aerofoil element 705 is rotatable relative to the first aerofoil element 703 about at least one vertical axis to allow the wing sail 701 to both adjust its camber and be folded into a close-packed configuration such as that shown in configuration 757 of FIG. 18. In some examples, the at least one vertical axis may comprise two vertical axes. At least one linear actuator, preferably a hydraulic ram, may be coupled to the first and second aerofoil elements.

[0160] According to some examples, a first axis 762 for rotation of the second aerofoil element 705 relative to the first aerofoil element 703 may be located in the first aerofoil element 703, and a second axis 763 for rotation of the second aerofoil element 705 relative to the first aerofoil element 703 may be located in the second aerofoil element 705. An axis 798 may be provided for rotation of the first aerofoil element 703 relative to the base of the wing sail. To link the first aerofoil element 703 and the second aerofoil element 705 and create two axes of rotation, the two aerofoil elements may be connected by an intermediate connecting member 771. The intermediate connecting member 771 may contain spherical or roller bearings, or other forms of mechanical bearings or revolute joints, to freely connect the connecting member to the first aerofoil element 702 and the second aerofoil element 705. The linking member 770 may comprise a top bar 772 and a bottom bar 773 which may be connected by a torsion structural member 774 to align the top and bottom bars to resist any torsional moment between the tip and base of the wing. The torsion structural member 774 may comprise a torsion spar, may be spherical and may be constructed of steel, aluminum or composite. A bottom linear actuator 765 (preferably a hydraulic ram) at the base of the wing connects to both the linking member 771 (preferably the bottom bar 773) and the structure of the first aerofoil element 703, preferably the base structure 784 of the first element, to control the relative movement of both members. Similarly, the wing sail 701 may comprise a top linear actuator 764 (preferably a hydraulic ram) connecting the top bar 772 of the connecting member 771 to the structure of the first aerofoil element 703 and may be connected to the end structure 783 of the first element. The connection of the linear actuators 764 and 765 to the wing sail 701 may be on a pin fixed between two arms fixed to each part of the wing sail 701, allowing said connection to rotate freely with changing angles.The top linear actuator 764 and the bottom linear actuator 765 are preferably used to drive the rotation of the linking member 771 relative to the first aerofoil element 703. The connection points of the rams 764 and 765 to the linking member 771 may be on both the top and bottom bars, and preferably the connection is rotatable relative to the linking member 771. In addition to the top bar 772 and the bottom bar 773, the linking member may comprise other linking bars spaced between these two bars, which may also be fixed in a torsion structure. These linking bars may also comprise rotation bearings connecting the first aerofoil element 703 to the second aerofoil element 705 and allowing them to rotate between each other by two perpendicular axes. The first axis 762 is preferably a perpendicular axis, preferably a perpendicular axis in the first aerofoil element 703, passing through the centre of each bearing connecting the first aerofoil element 703 to the linking member 771. The second axis 763 is a vertical axis, preferably a vertical axis within the second airfoil element 705 and preferably passes through the centre of each of the bearings connecting the second airfoil element 705 to the connecting member 771 .

[0161] The full range of motion of the wing sail 701 according to some examples is shown in FIG. 22. To adjust and reverse the camber of the wing sail 701, the second aerofoil element is rotated about the first axis 762 to complete the range of motion required to actively trim the wing and optimize the aerodynamic flow. This motion may be controlled by one or more linear actuators, preferably one top linear actuator 764 at the top 791 of the wing sail 701 and one bottom linear actuator 765 at the bottom 792 of the wing sail 701 as shown in FIGS. 20 and 21. As depicted in FIG. 22, configuration 766 indicates a neutral "winged" configuration, configuration 767 indicates maximum camber to starboard (typically in the range of 10-25 degrees from center), and configuration 768 indicates maximum camber to port (typically in the same range as maximum camber to starboard 767).

[0162] To fold the wing sail 701 into its stowed configuration, the second aerofoil element 705 is rotated about its first axis 762 to a maximum rotation position, which in some instances may be the position where the minimum stroke of the ram (or another linear actuator) is achieved. This is shown as configuration 769. The second aerofoil element 705 is then rotated about 90 degrees about its second axis 763 relative to the first aerofoil element 705 2 to form a close-packed configuration 770. This close-packed configuration 770 preferably minimizes the combined length 793 and thickness 794 of both the first aerofoil element 703 and the second aerofoil element 705, resulting in an orientation of the second aerofoil element 705 relative to the first aerofoil element 703 that is opposite to the feathered configuration 766. The centre lines of the first 703 and second 705 aerofoil elements may be parallel or up to about 40 degrees in this arrangement, with the second 705 preferably within the length of the first 703 aerofoil element. This rotation about the second axis 763 may be controlled by a rotary actuator or secondary ram arrangement connected between the linkage 771 and the second 705 aerofoil element, preferably a hydraulic linear ram or a hydraulic rotary actuator. If a hydraulic linear ram is used, this creates a series of dual ram arrangements that allows the second 705 to rotate greater than 180 degrees relative to the first 703 aerofoil element. The same angles may be achieved using a rotary actuator.

[0163] Once the sequence of folding the second aerofoil element 705 is completed (as described above and in FIG. 22), the wing sail 701 is ready to be folded up towards the deck in preparation for port operations. This process is illustrated in FIG. 24. The base 706 of the wing sail 701 is connected via a hinge structure to a pivotable plate 778 which is connected to the base structure 706, preferably a steel fabricated structure made of welded plates and flanges. This hinge structure allows the wing sail 701 to rotate about a horizontal axis 795 to transition between an upright coherent configuration 775 (upright) and a stowed configuration 776 (horizontal). Hydraulic cables and other low voltage electronic cables may be routed from the inside of the base 761 through openings in the pivotable plate 778 into the wing sail 701.

[0164] The wing sail 701 in its upright, coherent configuration 775 is lowered to its stowed configuration 776 by two linear actuators, preferably hydraulic rams 777, which are now loaded in tension with the weight of the wing sail 701. One single ram can raise and lower the wing sail 701, and the second of these two rams relieves the load on the one single ram, providing redundancy to the system in case one of the rams or its system fails. Repeating the same process in the reverse direction transitions the wing sail 701 from its stowed configuration to its upright, operational configuration.

[0165] In its stowed configuration, the wing sail 701 is positioned horizontally, ideally parallel to the deck of the vessel. The tip of the wing sail 701 is supported by supports on the deck and a fixing pin secures it. In bulk carriers, the base of the wing is preferably mounted on the side deck between the hatch cover slides and is preferably lowered to the stowed configuration above the hatch covers. The hatch covers can be slid under the stowed wing sail 701, allowing port operations to be uninterrupted. The wing sail 701 is preferably positioned at least 2 meters above the deck to allow traffic underneath. In the case of bulk installations and other installations where deck space is limited, the ram may be mounted on the underside of a pivotable plate 778 or may be positioned within a cavity in the deck. If deck space is not limited, the ram may be positioned above the deck as shown in FIG. 24.

[0166] In some examples, the structure of the wing sail 701 is simple and robust, which minimizes the overall cost of the wing sail 701 and allows the wing sail to "pay for itself" in a shorter period of time through fuel savings. FIG. 25 shows the bare structure 779 of the wing sail 701, with the first aerofoil element fairing 780 and the second aerofoil element fairing 781 removed for clarity. The main structure may include a main spar 782 which may be connected to a first element base structure 784 and a first element end structure 783, and may be connected to a number of structural ribs 797 to support the first aerofoil aerodynamic fairing 780. In another embodiment of the invention, the main structure may not include the structural ribs 797. The main spars 782 project below the first aerofoil element 703 and the first element base structure 784 and are attached to the top of a bearing structure 785, preferably a hydraulically driven slewing gear bearing, allowing the sail 701 to rotate approximately 360 degrees relative to the base and the vessel. Loads can be transferred and spread evenly across the bearings to minimize localized stress concentrations that can adversely affect the rotation of the device. These loads are transferred and spread through triangular flanges, preferably welded to the main spars 782, and then plates bolted to the top of the bearing structure. These triangular flanges may be constructed of steel plates. Other methods of transferring loads from the main spars 782 and the bearings may also be used.

[0167] In some examples, the underside of the bearing structure 785 is bolted to a pivotable plate 778, which is preferably a steel plate with structural reinforcement flanges. The pivotable plate 778 is connected to the wing sail base 761 by a hinge structure with a horizontal axis 795 along one edge of the pivotable plate 778 and by a fixed pin structure on the other edge of the pivotable plate 778. The base 761 is preferably a steel fabricated structure made up of welded steel plates and a number of welded steel flanges to transfer forces and moments from the wing sail 701 to the deck, existing and modified structure of the vessel. The base 761 is preferably bolted or welded to the deck and loads are transferred to the substructure.

[0168] In some examples, the first element base structure 784, the first element end structure 783 and the structural ribs 797 are preferably constructed of steel plate sections welded together to form a support for the first element fairing 780. They may also be constructed of aluminum or composite. The first element fairing is connected to the base support structure 34 and the end support structure 783. The fairing may be connected by mechanical fasteners or may be chemically bonded. The first aerofoil aerodynamic fairing 780 and the second aerofoil element aerodynamic fairing 781 are preferably constructed of composite, but may also be constructed of curved steel or aluminum plates.

[0169] The main spar 782 may be constructed of a steel box or I-beam section, or other construction method that provides a structurally efficient shape in bending and torsion. The main spar 782 must carry all of the load buildup generated by the wing sail 701 to the base of the wing.

[0170] The first aerofoil element 703 may be coupled to a coupling member 771 that is rotatable relative to the first aerofoil element 703 about a first axis 762. The first aerofoil element 703 may include at least two bearings for coupling to the rotatable coupling member 771. Preferably, the first aerofoil element may include a double shear structure 786, 790 as shown in Figure 25.

[0171] Figure 25 shows the structure of the wing sail 701 with emphasis on the connecting member 771 to show how it fits within the rest of the wing sail structure. Figure 25 also shows a close up of the first element base structure 784, the second element base structure 788, and the connecting member 771, showing how these parts connect and rotate together to form a double sided shear pin structure. The following details are described for the base of the wing, however the mechanism is presumed to be similar for the tip of the wing and may be found anywhere else along the first axis 762.

[0172] In some examples, the first element structure (which may include first element base structure 784, first element end structure 783, and structural ribs 797) may house at least two bearings, but preferably includes more than two bearings. While Figure 26 shows one example of a dual bearing assembly embedded within the first element base structure, this assembly may be found anywhere within the structure of the first airfoil element 703 along the first axis 762, and is repeated in this example within the first element end structure 783, not shown in detail.

[0173] The bearing assembly shown in FIG. 26 may include a top bearing 796a and a bottom bearing 766b, which may be spaced apart with a space between them to accommodate the bottom bar 773. The top bearing 766a and the bottom bearing 766b may be mechanically linked or coupled to the linking member torsion structure 774 to allow rotation of the linking member 771 relative to the first element base structure 784. The use of two bearings 796a and 796b creates a double shear structure that improves the stability of the connection and limits transverse rotation of the linking member 771 relative to the first element base structure 784. A bearing 796c may be provided for rotation of the second aerofoil element relative to the linking member 771. In another embodiment of the invention, one single bearing may be used to connect the linking member 771 to the first element base structure 784. If a single bearing is used, the bearing may be a self-aligning bearing and may be capable of self-aligning so that when rotated with the off-axis shaft, i.e., when deflection of the wing sail structure under load causes the top of the wing sail 701 to deflect and rotate at a greater angle than the bottom of the wing sail 701, the bearing maintains motion about the first axis 762 between the connecting member 771 and the first element base structure 784.

[0174] The bearings 796a and 796b may be cylindrical or self-aligning and must support the load of the second aerofoil element 705 while allowing the linking member to rotate freely about the first axis 762. These bearings may transfer all loads from the linking member 771, including the weight of the linking member 771 and the second aerofoil element 705, to the first element base structure 784 and the first element end structure 783. The bearings may be housed within the structural ribs 797 or other structure within the first aerofoil element 703. Conversely, the structural ribs may include space along the first axis 762 to allow the torsion beams 774 of the linking member 771 to rotate freely without contacting the structural ribs 797.

[0175] The connecting member 771 rotates relative to the first aerofoil element 703 and may be connected to the second aerofoil element 705 via a bearing structure housed within the structure of the second aerofoil element 705 and acting along a second axis 763. The bearing structure may be connected to a torsion structural member 787 that connects the top and base of the second aerofoil element 705 and resists torsional forces and moments acting between the top and base of the second aerofoil element 705 and prevents the aerofoil element from twisting in the opposite direction.

[0176] The connection between the linking member 771 and the second aerofoil element 705 may be via two or more bearings fixed to a torsion structure 787, which may be fixed to a second element base structure 788 and a second element end structure 789. This bearing structure allows the second aerofoil element 705 to rotate relative to the linking member about a second axis 763. This torsion structure 787 resists torsional forces and moments between the top and bottom of the second aerofoil element 705, minimizing deflection of the element at the top relative to the bottom. This provides structural robustness and avoids damage due to excessive bending of the aerofoil element.

[0177] Similar to the aerodynamic fairing 780 of the first aerofoil element, the aerodynamic fairing 781 of the second aerofoil element may be connected to the structure of the second aerofoil element 705. The aerodynamic fairing 781 of the second element may be connected to the structure of the second aerofoil element 705 by mechanical fastening or bonding to the second element base structure 788, the second element end structure 789, and the structural ribs 797 of the second aerofoil element 705, or by connection to any combination of these components. These connections preferably comprise mechanical fasteners or bonds, and the second aerofoil element fairing 781 may be preferably constructed of composite, but may also be constructed of steel or aluminum plate.

[0178] The first aerofoil element fairing 780 and the second element fairing 781 are preferably constructed in two half sections and may be glued or mechanically fastened, or may be constructed of smaller plates bonded or mechanically fastened to structural ribs 797, or may be made of smaller halves. The structure of the second aerofoil element 705 may be constructed of machined steel plate, composite or aluminium.

[0179] The all-metal structure of the wing sail 701 may be painted with a corrosion-resistant paint to reduce corrosion during use in salty, highly corrosive environments.

[0180] The base and end support structures for the first and second aerofoil elements (783, 784, 788 and 789) may comprise base and end plates which may be attached to improve the aerodynamic performance of the device by reducing vortex shedding which occurs as a result of the generation of lift.

[0181] 27 shows a cross section of an example wing sail 801 with multiple exhaust ports 809a, 809b, 809c, 809d, 809e, 809f, 809g, and 809h on the leading (forward) aerofoil. The wing sail 801 may operate similarly to the wing 101, although it has multiple exhaust ports on the forward aerofoil instead of one single exhaust port (exhaust port 109 on the aerofoil 103). The wing sail 801 may include a pressurized cavity 880.

[0182] A number of exhaust ports 809a, 809b, 809c, 809d, 809e, 809f, 809g, and 809h may be provided at a particular height of the wing sail 801, for example at the base of the wing sail 801 or at the top of the wing sail 801. In some examples, the exhaust ports are spaced apart between the base of the wing sail 801 and the top of the wing sail 801. The wing sail 801 may also include one or more intake ports on the forward aerofoil (not shown in FIG. 27 for clarity). In some examples, the one or more intake ports may be at a different height than the exhaust ports. The multiple exhausts 809a, 809b, 809c, 809d, 809e, 809f, 809g, and 809h may act similarly to the single exhaust 109 of the wing sail 101 in providing high energy airflow to the wing surface to reinvigorate the boundary layer, thereby increasing the angle of attack of the wing sail 801 achievable before stall and increasing the achievable lift coefficient of the wing sail 801. The multiple exhausts 809a, 809b, 809c, 809d, 809e, 809f, 809g, and 809h may be configured to close the low pressure side exhausts, thereby directing the airflow to the high pressure side of the aerofoil instead of the low pressure side. In some examples, the exhausts of the first aerofoil element shown in FIG. 27 are located within the aft half of the aerofoil element towards the trailing edge. In another example, one or more of these exhaust ports may be located within the front half of the leading (forward) airfoil element.

[0183] Wing sail 801 may, in some examples, be comprised of wing sail "units" that can be repeated to provide a modular wing sail, such as wing sail 621.

[0184] Although eight exhaust ports are shown on the leading aerofoil of the wing sail 801, it will be understood that in other examples a greater or lesser number of exhaust ports may be used.

[0185] 28 shows a cross section of an example wing sail 901 with multiple exhaust ports 909a, 909b, 909c, 909d, 909e, 909f, 909g, and 909h. The wing sail 901 may operate similarly to the wing sail 801, although it has multiple exhaust ports 984a, 984b, 984c, 984d, 984e, 984f, 984g, and 984h on the trailing aerofoil. The wing sail 801 may include a pressurized cavity 880.

[0186] A number of exhaust ports 984a, 984b, 984c, 984d, 984e, 984f, 984g, 984h may be provided at a particular height of the wing sail 901, for example at the base of the wing sail 801 or at the top of the wing sail 901. In some examples, the exhaust ports are spaced apart between the base of the wing sail 901 and the top of the wing sail 901. The wing sail 901 may also include one or more intake ports on the forward aerofoil (not shown in FIG. 28 for clarity). In some examples, the one or more intake ports may be at a different height than the exhaust ports. The multiple exhausts 909a, 909b, 909c, 909d, 909e, 909f, 909g, and 909h may act similarly to the single exhaust 109 of the wing sail 101 in providing high energy airflow to the surface of the wing to reinvigorate the boundary layer, thereby increasing the angle of attack of the wing sail 901 achievable before stall and increasing the achievable lift coefficient of the wing sail 901. The multiple exhausts 909a, 909b, 909c, 909d, 909e, 909f, 909g, and 909h may be configured to close the low pressure side exhausts, thereby directing the airflow to the high pressure side of the aerofoil instead of the low pressure side. In some examples, the exhausts of the first aerofoil element shown in FIG. 28 are located within the aft half of the aerofoil element towards the trailing edge. In another example, one or more of these exhaust ports may be located within the front half of the leading (forward) airfoil element.

[0187] Wing sail 901 may, in some examples, be comprised of wing sail "units" that can be repeated to provide a modular wing sail, such as wing sail 621.

[0188] Although eight exhaust ports are shown on the leading and trailing aerofoils of the wing sail 901, it will be understood that a greater or lesser number of exhaust ports may be used in other examples.

[0189] Figure 29a shows the wing sail 101 in an upright position.

[0190] Figure 29b shows the wing sail 101 in a folded, stowed configuration, where the trailing aerofoil 105 has been rotated relative to the leading aerofoil 103 such that the chord lines of each aerofoil are at a substantially 90 degree angle with respect to each other, and both aerofoils 103 and 105 have been rotated from the base of the wing sail to a horizontal position controlled by one or two articulated rams 777 at the base of the wing sail to form the stowed configuration shown in Figure 29b. The stowed configuration of Figure 29b is configured in some instances such that the wing sail 101 fits into a side channel between the vessel hatch and the side of the vessel, and the vessel hatch can slide under the leading aerofoil 103 to an open position, or can be folded next to the leading aerofoil 103, so that the wing sail 101 does not interfere with the operation of the vessel hatch. In the stowed configuration shown in FIG. 29b, the trailing (second) aerofoil 105 is rotated substantially 90 degrees relative to the first aerofoil element, which in some instances allows the second aerofoil element to remain within the beam width of the vessel. The chord length of the second aerofoil element 105 is dimensioned so that it can be folded into this stowed configuration and rest above the vessel's side deck, and the height of the first aerofoil element 103 above the vessel's side deck is dimensioned so that the vessel's hatch covers can slide underneath. By incorporating boundary layer flow control into the design of the wing sail 101, smaller devices can be fitted to the vessel while still generating thrust similar to larger devices. Here, the smaller devices can be stowed in the stowed configuration as described above to minimize the impact on port operations and vessel loading and unloading, where the vessel's hatches need to be articulated from closed to open and cargo may be removed from the vessel's holds and may move over the wing sail 101 in the stowed configuration shown in FIG. 29b. To obtain a given amount of thrust, the planar area of ​​a sail using boundary layer flow control can be smaller than if the sail did not have the boundary layer flow control function.In other words, the wing sail described in this disclosure can generate more thrust with less total plan area (which can be considered as the combined cross-sectional area of ​​both aerofoils along their chord lines from base to tip) than previous wing sails due to the boundary layer flow control of the wing sail described in this disclosure. The reduced plan area allows, in some examples, the wing sail described in this disclosure to achieve a compact storage arrangement that fits into a side channel between a vessel hatch and the side of the vessel while still generating the thrust required for the vessel.

[0191] Figure 30 shows the wing sail 101 in a stowed configuration relative to a marine vessel (ship). As shown in the figure, the wing sail 101 in the stowed configuration fits into a side channel between the vessel's hatch and the side of the vessel, and allows the vessel's hatch to slide underneath.

[0192] FIG. 31a shows the base structure of an energy saving device for a marine vessel. The energy saving device may comprise an energy generating device such as a wind propulsion device (such as a wing sail, a Flettner rotor, a turbo sail, a kite, etc. described in this disclosure) or a wind turbine (having a vertical or horizontal axis). The base is designed to be fixed to the deck of a vessel (such as any vessel described in this disclosure, a bulk carrier, a tanker, a container ship, a RORO ship, an LNG ship, a ferry, a cruise ship, etc.) and comprises three or more vertical columns 3003. Each vertical column 3003 may have a cylindrical cross section, an I-beam cross section, a square cross section, or other cross section. Each vertical column 3003 may be fixed to the deck of the marine vessel via a flange and bolt pattern or other method. The columns 3003 hold the structural platform 3004 of the device at a height of at least 2m above the vessel deck, leaving enough working space below to allow normal operation of the vessel.

[0193] A linear actuator 3002 for raising and lowering the wind propulsion device 3001 may be mounted on the deck or, as shown in Figures 31a-c, on a platform 3004 above a support 3003. The linear actuator 3002 may, for example, comprise one or more lifting rams. By mounting the linear actuator on a platform 3004 above the deck, the probability of an accident involving the linear actuator 3004 and crew working on the deck can be reduced.

[0194] By having the wind propulsion device above deck level, the wind propulsion device 3001 has less impact on the deck layout (due to deck space being saved). According to some examples, the height of the pylon 3003 is at least 2m to allow crew work to be performed below the platform 3004. According to some examples, the height of the pylon 3003 is less than 4m to reduce the length of the moment arm between the deck and the platform 3004, thereby reducing stresses on the fixation of the pylon 3003 to the deck of the marine vessel when wind applies a moment to the device above its base and / or dynamic loads from the rolling or pitching moments of the marine vessel.

[0195] Figure 31b is a further view of the base structure of Figure 31a. Figure 31c shows an example of a base structure having three struts 3003 rather than four as shown in Figures 31a and 31b.

[0196] Figures 32a to 32d compare the difference in airflow between an example wing sail with and without air inlets, and also compare different air inlet locations on an example wing sail.

[0197] Figure 32a shows the sail with an angle of attack 3210a of 20 degrees relative to the airflow 3230. In this figure, there is no suction (inlet or pressurized exhaust). The airflow remains attached until it reaches 60% of the chord length of the first aerofoil element 3203a of the sail, at which point it separates into a turbulent region and the sail is said to be stalled. The flow does not reach the second aerofoil element 3203b. In this case, there is little lift and drag.

[0198] Figure 32b again shows the wing sail at an angle of attack 3210b of 20 degrees relative to the airflow 3230. The example wing sail of Figure 32b incorporates suction by an inlet 3207b towards the rear quarter of the chord length of the first aerofoil element 3203b, and a pressurized exhaust at the trailing edge of the first element. The pressurized inlet 3207b is located close to where the flow separates, "sucking" the flow at this point, removing the turbulent boundary layer and keeping the flow attached along the aerofoil elements 3203b and 3205b. This means that even at angles 3210b where it would otherwise stall, the wing sail still functions well as an aerofoil, and can achieve more lift due to the larger pressure difference between the high (H) and low (L) pressure regions due to the high angle of attack.

[0199] Figure 32c shows a wing sail with an angle of attack 3210c of 30 degrees relative to the airflow 3230. In this example, there is no suction (intake or pressurized exhaust). The airflow remains attached for the first 30% of the chord length of the first element. Compared to Figure 32a, the angle of attack 3210c of the wing sail is larger, so separation occurs closer to the leading edge of the first element than the trailing edge. Again, this arrangement is stalled, has less lift and more drag, and should be avoided.

[0200] FIG. 32d again shows a wing sail with an angle of attack 3210d of 30 degrees relative to the airflow 3230. The wing sail of FIG. 32d is equipped with a suction mechanism, with an inlet towards (within) the front quarter of the chord length of the first aerofoil element 3203d, and a pressurized exhaust at the trailing edge of the first aerofoil element 3203d. In this case, the pressurized inlet 3207 is located closer to the flow separation location, which occurs much closer to the leading edge than the trailing edge, and at this point it "sucks" the flow, removing the turbulent boundary layer and keeping the flow attached. As the inlet 3207d is located much closer to the leading edge of the first element 3203d, this means that a larger angle of attack 3210d can be achieved for the entire wing sail compared to the wing sail of FIG. 32a, thereby increasing the pressure difference between the high (H) and low (L) pressure regions, generating more thrust and reducing fuel consumption of the vessel.

[0201] Of course, it will be understood that the described examples are illustrative only and are not intended to limit the scope of the invention. The term "wing sail" does not limit the size or use of the wing sail. Additionally, the term "marine vessel" does not limit the size or use of the marine vessel. Marine vessels and / or wing sails may be provided in different sizes.

[0202] Of course, it will be understood that the described examples are merely illustrative and are not intended to limit the scope of the invention. It will also be understood that any of the above examples may be combined.

[0203] The figures are schematic in nature and are not necessarily drawn to scale. Moreover, it will be understood that aspects of the described examples can be combined in any manner.

Claims

1. It is a wing sail, a first aerofoil having a leading edge aforward of the sail and a trailing edge aft of the leading edge; a second aerofoil having a leading edge and a trailing edge, the leading edge of the second aerofoil being closer to a point of maximum cross-sectional width of the second aerofoil than the trailing edge of the second aerofoil; Equipped with the wing sail is configured such that the leading edge of the second aerofoil may be located aft of the trailing edge of the first aerofoil; Further, the first aerofoil has An intake port, Exhaust vent, and a flow passage within the first aerofoil connecting the intake port and the exhaust port; The airflow from the intake port is guided to the exhaust port by the flow path. A wing sail characterized by a.

2. 2. The wing sail of claim 1, wherein the second aerofoil has a first portion that includes the leading edge of the second aerofoil, the first portion being rounded.

3. The sail of claim 1 or 2, wherein the second aerofoil is symmetrical about a chord line of the second aerofoil.

4. 2. A wing sail as claimed in any preceding claim, wherein the airflow from the exhaust outlet is directed out of the exhaust outlet towards the leading edge of the second aerofoil.

5. A sail as claimed in any preceding claim, wherein the exhaust outlet is located at the trailing edge of the first aerofoil.

6. the air inlet comprises a port air inlet located on a port side of the first aerofoil and a starboard air inlet located on a starboard side of the first aerofoil; when the wing sail is in use on starboard tack, the first aerofoil is configured to direct airflow through the port intake and not through the starboard intake; and when the wing sail is in port tack, the first aerofoil is configured to direct airflow through the starboard intake and not through the port intake. A wing sail according to any preceding claim.

7. rotating the second aerofoil in a starboard direction relative to the first aerofoil such that the exhaust of the first aerofoil directs airflow towards the port leading edge of the second aerofoil when the wing sail is used on starboard tack; and and when the wing sail is used on port tack, the second aerofoil is rotated in a port direction relative to the first aerofoil such that the exhaust of the first aerofoil directs airflow towards the starboard leading edge of the second aerofoil.

7. The wing sail according to claim 6.

8. When the wing sail is used on starboard tack, it draws air into the port intake and does not draw air into the starboard intake; and the wing sail is configured to draw air into the starboard intake and not draw air into the port intake when the wing sail is in port tack; A wing sail according to claim 6 or 7.

9. a pressure differential generator within the first aerofoil; the pressure differential generator is configured to generate a negative internal pressure within the first airfoil; The negative internal pressure draws air into the device body through the air intake. A wing sail according to any preceding claim.

10. The pressure differential generator is One or more fans driven by a motor, or A series of fans driven by a motor and connected by a single fan shaft Equipped with 10. The wing sail according to claim 9.

11. the flow path includes the pressure differential generator and a vent; A wing sail as claimed in claim 9 or 10.

12. the flow passage is configured to direct flow from the inlet at an initial location along the span of the first aerofoil and direct the flow to the exhaust; 2. A wing sail as claimed in any preceding claim, wherein the span of the first aerofoil is the distance from a root of the first aerofoil to a tip of the first aerofoil.

13. one or more wing sail modules; the wing-sail modules are configured to be stacked vertically on one another; Each vertically stacked module includes an air inlet, an air outlet, a pressure differential generator, and a ventilation port. A wing sail according to any preceding claim.

14. The flow path includes an internal flow straightener. A wing sail according to any preceding claim.

15. the second aerofoil rotates relative to the first aerofoil to a maximum rotation position to minimize the overall span of the sail; The wing sail folds at the base of the wing sail to form a stowed configuration. A wing sail according to any preceding claim.

16. a protective casing for covering the first and second aerofoils in the stowed configuration; the protective casing allows the sail to be raised and / or lowered, and when the sail is lowered and in the stowed position, is capable of covering the sail by performing at least one of folding, rotating and rolling along a track.

16. The wing sail according to claim 15.

17. control software for opening and closing the air inlets or directing airflow from one air inlet to the next; and a mechanical control system for opening and closing said air inlet; At least one of the following: A wing sail according to any preceding claim.

18. a mechanical system actuated to open and close the intake based on movement of the second aerofoil. A wing sail according to any preceding claim.

19. the second aerofoil is provided with at least one air inlet; A wing sail according to any preceding claim.

20. the second aerofoil having at least one exhaust port; A wing sail according to any preceding claim.

21. the first aerofoil having a plurality of air intakes; A wing sail according to any preceding claim.

22. the first aerofoil having a plurality of exhaust ports; A wing sail according to any preceding claim.

23. the first aerofoil includes at least one exhaust port disposed between a portion of the first aerofoil including the leading edge and a portion of the first aerofoil including the trailing edge. A wing sail according to any preceding claim.

24. the second aerofoil includes at least one exhaust port disposed between a portion of the second aerofoil including the leading edge and a portion of the second aerofoil including the trailing edge. A wing sail according to any preceding claim.

25. rotating the second aerofoil relative to the first aerofoil so that the chord lines of each aerofoil are substantially perpendicular to one another; and the sail is configured to form a stowed configuration by rotating both aerofoils from the base of the sail to a horizontal position. A wing sail according to any preceding claim.

26. The sail comprises a base structure; the base structure comprises three or more columns supporting a platform; each of the three or more columns having a height between 2 meters and 4 meters; the first aerofoil and the second aerofoil are disposed above the platform. A wing sail according to any preceding claim.

27. a linear actuator for raising and lowering the wing sail, the linear actuator being disposed above the platform; 27. The wing sail of claim 26.

28. the inlet of the first airfoil element is located within a forward quarter of the chord length of the first airfoil element; A wing sail according to any preceding claim.

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