JP2025160959A - Submersible hydrofoil vessel and method of surfacing and submerging a submersible hydrofoil vessel - Google Patents

Abstract

To provide a submersible hydrofoil boat, and a floatation and submersion method of the submersible hydrofoil boat capable of performing a floating navigation under small waves and requiring a high speed, and capable of performing a submerging navigation under big waves and requiring a stealth property.SOLUTION: A submersible hydrofoil boat 1 or 1A is constituted by having a main hull 10 and a hydrofoil 20 arranged at a distance from the main hull 10. The submersible hydrofoil boat is configured so as to generate upward lift Lu by the hydrofoil 20 when navigating by raising the main hull 10 from a stopping position, and generate downward lift Ld by the hydrofoil 20 when navigating under the submerging the main hull 10 from the stopping position.SELECTED DRAWING: Figure 1

Description

The present invention relates to a submersible hydrofoil vessel and a method for surfacing and submerging a submersible hydrofoil vessel. More specifically, the present invention relates to a submersible hydrofoil vessel and a method for surfacing and submerging a submersible hydrofoil vessel, which has hydrofoils on the main hull and can temporarily submerge the main hull to allow it to submerge.

A typical hydrofoil vessel travels at high speeds with its main hull completely floating above the water surface due to the upward lift generated by semi-submerged hydrofoils (such as V-shaped foils), in which part of the foil is above the water surface, or fully submerged hydrofoils (such as horizontal foils), in which the entire foil is below the water surface. In conventional technology, these hydrofoil vessels do not submerge their main hulls. Furthermore, with regard to unmanned vehicles, drones, and other such vessels, vessels that travel on the water surface (unmanned surface vehicles (USVs)) and vessels that travel submerged (unmanned underwater vehicles (UUVs)) are considered to be different types of vessels.

Meanwhile, semi-submersible vessels and small submarines are increasingly being used as relatively small vessels for smuggling. However, while submarines and other vessels that primarily navigate underwater and temporarily navigate on the surface are in practical use, there are almost no vessels that primarily navigate on the surface and are also capable of underwater navigation.

For example, an unmanned surface vehicle (ASV) equipped with a cooling structure for cooling heat-generating elements has been proposed as a surface vehicle (see, for example, Patent Document 1). A surface vehicle equipped with a water jet propulsion system has also been proposed (see, for example, Patent Document 2). Both of these main hulls have a displacement-type hull shape.

Moreover, underwater vehicles generally have torpedo-shaped or cylindrical hulls. For example, an underwater vehicle capable of rapid submerged and horizontal navigation with low energy consumption has been proposed (see, for example, Patent Document 3). This underwater vehicle is equipped with an underwater vehicle main body with a streamlined front end that faces the direction of travel during horizontal navigation, ballast whose rear end is fitted into the front end of the underwater vehicle main body and whose own front end is also streamlined, and ballast holding means that detachably holds the ballast at the front end of the underwater vehicle main body.

On the other hand, with regard to hydrofoil vessels, a fully submerged hydrofoil vessel has been proposed that has a pair of fully submerged hydrofoils, one at the front and one at the rear, and that is equipped with multiple strain gauges arranged on each of a pair of left and right struts that support the hydrofoils or each hydrofoil, and a flap control circuit that controls the flaps of each hydrofoil based on the output signals of each strain gauge (see, for example, Patent Document 4). The purpose of this fully submerged hydrofoil is to reduce the motion of the hull and stabilize its attitude even when the foils are sailing through waves.

Japanese Patent Application Laid-Open No. 2019-142368 Japanese Patent Application Laid-Open No. 2018-135037 JP 2010-47094 A Japanese Unexamined Patent Publication No. 7-187055

In this type of hydrofoil vessel, the main hull remains above the water surface, and only the hydrofoils and their support parts are subjected to water resistance, resulting in reduced propulsion resistance and enabling high-speed sailing with low fuel consumption. However, because the lift of the hydrofoils changes as their submerged depth changes, they are susceptible to the effects of waves when propelling through rough waves, and in rough weather, high waves can cause them to hit the bottom of the main hull.

The present invention has been made in light of the above, and its object is to provide a submersible hydrofoil vessel and a method for surfacing and submerging a submersible hydrofoil vessel that can navigate at high speeds by surface navigation when waves are small, and can submerge and navigate underwater when waves are large or stealth is required.

The submersible hydrofoil vessel of the present invention, which achieves the above-mentioned objectives, is composed of a main hull and hydrofoils arranged at a distance from the main hull, and is characterized by generating upward lift on the hydrofoils to raise the main hull from a stationary position and sail, and generating downward lift on the hydrofoils to submerge the main hull from a stationary position and sail.

This submersible hydrofoil vessel uses hydrofoils to generate not only upward lift but also downward lift (sinking force), allowing it to operate not only with the main hull raised from a stationary position but also with the main hull submerged from a stationary position, thereby expanding its range of applications. Surface navigation allows for high-speed navigation and good fuel efficiency, allowing for long-distance navigation at high speeds. Submerged navigation also allows for avoidance of rough waves in rough weather, ensures anti-radar stealth capabilities, and reduces visibility.

However, in civilian use, the only time this submersible hydrofoil vessel would need to navigate submerged would be if the weather suddenly changed and it encountered rough seas. In reality, it would be suspended if it was determined that the weather was unsafe for navigation based on forecasted weather, so it is thought that there would be almost no need for it to navigate submerged. Therefore, it is thought that there would be almost no civilian use for it.

On the other hand, from a military perspective, because it can travel long distances at high speeds while surfaced, it can be launched from outside the enemy's attack range (out-range). Furthermore, because the wake left when surfaced is small, visibility and stealth against aerial searches can be improved. Furthermore, when in an area where it is easily detected by enemy radar or when it is being searched by enemy radar, it can switch to submerged navigation, reducing the radar area above the water surface and improving anti-radar and stealth capabilities. Furthermore, because it leaves almost no wake, visibility can be reduced.

Furthermore, unmanned submersible hydrofoils for suicide bombing and submersible hydrofoils for launching short torpedoes make it possible to attack areas below the surface of enemy ships where damage is greatest. Furthermore, by operating submerged, especially fully submerged, these submersible hydrofoils may be able to avoid surface attacks by enemy anti-ship missiles, machine guns, close-in defense systems, etc.

In addition, compared to torpedoes, submersible hydrofoils have a larger volume, and when traveling semi-submerged in shallow depths, they can be snorkeled using a diesel engine, allowing for long-distance navigation, and are inexpensive to manufacture. Furthermore, by providing a sail equipped with antennas and optical equipment, they can perform radar searches, detect enemy radar waves, optical detection, and exchange information with allies via radio when traveling semi-submerged, such as when surfaced or snorkeling.

As a result, for military purposes, submersible hydrofoils could be used as suicide vehicles for attacking unmanned surface vehicles (USVs), or as mother ships for launching short-range torpedoes. Furthermore, they could be used as small craft to support and recover infiltrators from landing, rescue pilots, and for landing.

The above-mentioned submersible hydrofoil vessel is also characterized by the fact that it can perform surfaced navigation, in which upward lift is generated on the hydrofoils, causing the main hull to be in a surfaced or semi-surfaced state and sailing, and submerged navigation, in which downward lift is generated on the hydrofoils, causing the main hull to be in a fully submerged or semi-submerged state and sailing.

The states used here refer to the following: "Main hull surfaced" refers to a state in which the main hull is completely surfaced relative to the still water surface. "Semi-surfaced" refers to a state in which the volume Vmu of the main hull above the water surface relative to the still water surface is greater than or equal to 50% and less than 100% of the main hull's volume Vmt (0.50≦(Vmu/Vmt)<1.00).

Furthermore, "semi-submerged state" refers to a state in which the volume Vmu of the main hull above the water surface relative to the still water surface is greater than 0% but less than 50% of the volume Vmt of the main hull (0.00 < (Vmu/Vmt) < 0.50). Furthermore, "completely submerged state" refers to a state in which the main hull is completely submerged relative to the still water surface.

The terms "navigation" and "semi-surfaced navigation" used here refer to the following: "navigation with the main hull surfaced" refers to navigation with the "main hull surfaced," and "semi-surfaced navigation" refers to navigation in a "semi-surfaced state." Furthermore, "fully submerged navigation" refers to navigation in a "fully submerged state," and "semi-submerged navigation" refers to navigation in a "semi-submerged state." "Navigation with the main hull surfaced" and "semi-submerged state" are collectively referred to as "surfaced navigation." Furthermore, "fully submerged navigation" and "semi-submerged navigation" are collectively referred to as "submerged navigation."

Note that "semi-submerged navigation" includes "semi-submerged main hull navigation," in which more than half of the main hull is submerged, but part of the main hull is raised above the waterline; "surfaced sailing," in which the entire main hull is submerged, but part or all of the sail is raised above the waterline; and "periscope depth navigation," in which the sail is submerged, but the periscope and other equipment are raised above the waterline.

Furthermore, if the hydrofoil in the above-mentioned submersible hydrofoil vessel is a fully submerged hydrofoil, the hydrofoil is submerged to a great depth, just like fully submersible hydrofoil vessels in conventional technology, so there is little lift fluctuation due to the influence of the water surface (free surface), and the lift is also large, resulting in little propulsion resistance. Furthermore, there is the advantage that lift can be easily controlled during both surfaced and submerged navigation.

Furthermore, if the hydrofoils in the above-mentioned submersible hydrofoil vessel are semi-submersible hydrofoils, then like semi-submersible hydrofoil vessels of the prior art, they can navigate in shallow waters, and have the advantage of being able to easily control roll, as the hydrofoils provide the restoring force against rolling and other movements during surfaced navigation.

Furthermore, if the above-mentioned submersible hydrofoil vessel is equipped with a wing lifting mechanism that changes the distance between the main hull and the hydrofoils, the submerged depth of the hydrofoils can be changed depending on the wave conditions on the water surface and the depth of the navigation area during both surfaced and submerged navigation, allowing the hydrofoils to perform to their full potential and be made smaller. Furthermore, by abutting the hydrofoils against the bottom of the main hull, the vessel can be used as a displacement vessel or a planing vessel and navigate in shallow waters.

Alternatively, if the submersible hydrofoil vessel described above stores the hydrofoils inside or adjacent to the main hull and is equipped with a storage and deployment mechanism for deploying the stored hydrofoils, storing the hydrofoils during submerged navigation can reduce propulsion resistance during submerged navigation and improve propulsion efficiency. Furthermore, when it is time to surface again, the hydrofoils can be deployed for surface navigation.

Alternatively, if the above-mentioned submersible hydrofoil vessel is equipped with a wing separation mechanism that separates the hydrofoils from the main hull, separating the hydrofoils during submerged navigation can reduce propulsion resistance and mass during submerged navigation, significantly improving propulsion efficiency. In this case, after the hydrofoils are separated, they cannot be used again to surface.

The method for surfacing and sinking a submersible hydrofoil vessel of the present invention is characterized in that, in a submersible hydrofoil vessel having a main hull and hydrofoils arranged at a distance from the main hull, when the main hull is raised from a stationary state to sail, the hydrofoils generate upward lift, and when the main hull is submerged from a stationary state to sail, the hydrofoils generate downward lift.

This method for surfacing and lowering a submersible hydrofoil vessel allows the hydrofoils to generate downward lift in addition to upward lift, allowing the main hull to be lowered from a stationary position and used for sailing. In other words, simply by widening the range of motion of the hydrofoils or hydrofoil flaps, the main hull can be lowered from a stationary position and used for sailing. As a result, the uses of submersible hydrofoil vessels can be expanded. Furthermore, with this submersible hydrofoil vessel, there is no need to add or remove ballast water from ballast tanks for lowering the vessel, as is the case with submarines. Furthermore, by limiting the submergence depth during submerged sailing to a shallow depth, a pressure-resistant structure is not required, simplifying the structure of the main hull.

The method for surfacing and sinking a submersible hydrofoil vessel described above is characterized in that, when sailing, the hydrofoils generate upward lift to raise the main hull from a stationary state, or the hydrofoils generate downward lift to submerge the main hull from a stationary state, thereby sailing with the main hull in one of the following states: surfaced, semi-surfaced, semi-submerged, or fully submerged.

This method allows a submersible hydrofoil vessel to utilize the upward and downward lift of the hydrofoils, so even if the vessel is configured to be stopped in a variety of states from fully submerged to semi-surfaced, the main hull can be set to be fully submerged, semi-submerged, semi-surfaced, or fully surfaced. This allows for more flexibility in selecting the vessel's stopping state depending on the application, thereby expanding the uses of submersible hydrofoil vessels. For example, when recovering submersibles or rescuing pilots, the vessel can wait while stopped in a fully submerged or semi-submerged state. Furthermore, by providing the main hull with buoyancy that allows it to remain afloat when stopped, the vessel can safely remain afloat without sinking even in the event of a hydrofoil failure.

In the above-mentioned method for raising and lowering a submersible hydrofoil vessel, if ballast water is discharged from the ballast tanks when raising the main hull from a stationary state, and ballast water is poured into the ballast tanks when submerging the main hull from a stationary state, the main hull can be raised and lowered with less hydrofoil lift, allowing the hydrofoils to be made smaller. These ballast tanks can be installed on the main hull, hydrofoils, struts, etc., and can also be installed as detachable auxiliary tanks.

The submersible hydrofoil vessel and method for surfacing and submerging a submersible hydrofoil vessel of the present invention provide a submersible hydrofoil vessel with a relatively simple configuration that can travel long distances at high speeds when waves are small, and can travel submerged when waves are large or secrecy is required.

1 is a diagram showing a submersible hydrofoil vessel according to a first embodiment of the present invention; FIG. 2 is a diagram showing the propulsion mechanism and sail of a submersible hydrofoil vessel. This is a diagram showing a configuration in which a rudder and a horizontal rudder for diving are provided on the main hull of a submersible hydrofoil vessel. 1A-1C are diagrams showing various surfaced and submerged states of a submersible hydrofoil vessel; 1 is a diagram showing the relationship between the water surface during various surfaced and submerged navigation of a submersible hydrofoil vessel. FIG. 1 is a diagram showing the relationship between various surface navigations of a submersible hydrofoil vessel and the lift force of the hydrofoil. 1 is a diagram showing the relationship between various submerged navigational states of a submersible hydrofoil vessel and the lift force of the hydrofoil. 1A and 1B are diagrams showing the state of raising and lowering of hydrofoils in a submersible hydrofoil vessel. 1A and 1B are diagrams showing the retracted and deployed states of hydrofoils in a submersible hydrofoil vessel. 1A and 1B are diagrams showing the deployment and separation of hydrofoils in a submersible hydrofoil vessel. FIG. 1 is a diagram showing a submersible hydrofoil vessel according to a second embodiment of the present invention;

[Introduction] Below, we will explain a submersible hydrofoil vessel and a method for surfacing and sinking a submersible hydrofoil vessel according to an embodiment of the present invention, with reference to the drawings. Note that the coordinate system "X-Y-Z" used in the drawings refers to a right-handed coordinate system in which the fore-and-aft direction of the submersible hydrofoil vessel is the X direction, the left-and-right direction is the Y direction, and the up-and-down direction is the Z direction, with the forward, left, and up directions all being positive.

The size of the submersible hydrofoil vessel envisioned in this invention is equivalent to that of unmanned vehicles, boats, warships, ships, etc., which correspond to the size of vessels currently in use as hydrofoil vessels, and is assumed to be approximately 30m in length, 9m in width, 3m in depth, and up to 300 tons in gross tonnage.

The hydrofoil 20 provided on the submersible hydrofoil vessel 1 of the first embodiment is a fully submersible hydrofoil that is fully submerged below the water surface during surface navigation. The front hydrofoil 20A provided on the submersible hydrofoil vessel 1A of the second embodiment is a semi-submersible hydrofoil that is not fully submerged but remains partially above the water surface during surface navigation. The submersible hydrofoil vessel of the present invention may be equipped with either fully submersible hydrofoils or semi-submersible hydrofoils, or may be equipped with both.

[Submersible Hydrofoil Vessel of the First Embodiment] First, we will explain the submersible hydrofoil vessel 1 of the first embodiment of the present invention. As shown in Figures 1 to 3, this submersible hydrofoil vessel 1 is composed of a main hull 10, fully submersible hydrofoils 20, a propulsion mechanism 12, a control mechanism 13, etc.

[Main Hull] The main hull 10 may be either a monohull or a catamaran, as in conventional hydrofoil vessels, or may have another shape. The main hull 10 is normally configured to be watertight when submerged in the fully submerged state C4 or semi-submerged state C3 as shown in Figure 4. However, since the submersible hydrofoil vessel 1 does not dive as deep as a submarine, but travels at shallower depths, the main hull 10 only needs to be configured to withstand a submerged state, and does not need to have a pressure hull like a submarine.

For example, a very large tanker (VLCC) has a draft of around 20m, and at this depth of submergence, there is no need for pressure hull materials like those used in submarines. Also, if the submergence is achieved using the sinking force (downward lift) of the hydrofoils 20, it is not necessarily necessary to obtain the sinking force from the injection of ballast water. In this case, ballast tanks are not required, simplifying the structure.

By adjusting the relationship between the weight and buoyancy of the main hull 10 depending on the application, the main hull 10 can be placed in a variety of states when stopped, including a floating state C1, a semi-floating state C2, a semi-submerged state C3, and a fully submerged state C4, as shown in Figure 4. Furthermore, by providing ballast tanks 15 (Figure 2(b)) and buoyancy-imparting members (e.g., air bags, etc.; not shown), it becomes possible to more flexibly select floating states C1, C2, and submerged states C3, C4 as the state when stopped, and to easily maintain those states.

The main hull 10 is composed of a hull section 11 and, if necessary, a sail 14. The shape of the hull section 11 may be torpedo-shaped, submarine-shaped (fish-shaped, surface ship-shaped, teardrop-shaped (water drop-shaped), cigar-shaped (torpedo-shaped)), or other shapes depending on the intended use. Furthermore, if stealth against radar is a priority, the main hull 10 is shaped as an anti-radar stealth shape. Furthermore, since the submersion depth is relatively shallow and high strength is not required, it may be formed from radio wave-transparent or radio wave-absorbing materials, or coated with radio wave-absorbing or acoustically absorbing materials or paints, if possible.

[Propulsion mechanism, etc.] As shown in Figures 2(a) and 2(b), the propulsion mechanism 12 comprises an internal combustion engine 12a such as a diesel engine, a propeller 12d such as a water jet propeller or propeller, and a power transmission mechanism (not shown) between them. Furthermore, when the internal combustion engine 12a cannot be used in the fully submerged state C4, or when it is necessary to avoid the complexity and noise of the mechanical power transmission mechanism, a power generator 12b and a power storage device 12c are provided to electrically drive the propeller 12d.

The control mechanism 13 is equipped with various devices, such as a piloting device, an electrical equipment control device, and an electronic equipment control device, that operate the submersible hydrofoil vessel 1 and control the various onboard equipment. These controls may be crew-controlled, remote-controlled, or autonomous, or a combination of these. They may also be mechanically controlled, or electronically or electrically controlled.

[Sail] A sail 14 is provided to allow intake and exhaust for the engine when the vessel is submerged. This sail 14 is the part that is exposed above the water surface when the vessel is semi-submerged (C3), and protrudes upward from the top of the hull 11. When the vessel is submerged, the horizontal cross section of the sail 14 is streamlined to reduce the resistance, wave generation, and wake of the sail 14.

As shown in Figure 2(c), the sail 14 is equipped with a snorkel 14a for intake and exhaust of the internal combustion engine 12a, electronic equipment 14b for assessing the external situation through maritime radio search, maritime optical search, and radio communication, and optical equipment 14c. Examples of electronic equipment 14b include radar equipment, radar wave detection equipment, and communication equipment. Examples of optical equipment 14c include optical periscopes and optical communication equipment.

In particular, if anti-radar stealth is required for the submersible hydrofoil vessel 1, the sail 14 can be given an anti-radar stealth shape and made of radar-absorbing materials or painted to avoid radar detection. These measures are similar to those used for submarine sails, but because the submergence depth is much smaller, there is no need to consider the pressure resistance of the sail, which broadens the range of materials that can be used and increases the freedom of design and manufacturing. In addition, the snorkel 14a cools the exhaust gases to avoid infrared detection.

In addition, by receiving information about the surrounding situation from detection devices on other ships and aircraft, refraining from radio wave emissions, and only using external communication equipment, it is possible to reduce the amount of equipment carried, making the ship lighter, smaller, and less expensive, and more stealthy.

Furthermore, normally, the hydrofoils 20 and struts 30 provide the steering and submersible hydrofoil vessel 1 with its functions for navigation. However, when retracting or separating the hydrofoils 20, as described below, the main hull 10 may be equipped with steering mechanisms such as a rudder 13a and a horizontal submersible rudder 13b, as needed, as shown in Figure 3.

[Hydrofoil] While the hydrofoils of conventional hydrofoil vessels generate lift only in an upward direction, the fully submersible hydrofoil 20 of this submersible hydrofoil vessel 1 generates a downward lift (sinking force) Ld in addition to an upward lift Lu. Therefore, the wing's angle of attack is configured to be changeable both downward and upward, or the main body of the hydrofoil 20 is placed horizontally and the flap 20a is used to generate both an upward lift Lu and a downward lift Ld.

In addition, since the submerged depth of the fully submerged hydrofoil 20 is a depth where the free surface influence of the water is less than that of a semi-submerged hydrofoil, it is considered sufficient for the cross-sectional shape of this hydrofoil 20 to be a symmetrical foil. However, since the relationship between the weight and buoyancy of the main hull 10, as well as the surfaced state during surfaced navigation and the submerged state during submerged navigation, determines the relationship between the magnitude of the upward lift force Lu and the downward lift force Ld, a foil shape appropriate for each case will be used, taking into account numerical calculations and experimental results, etc.

If the hydrofoil 20 has an internal cavity, this cavity can be used as a fuel tank, but it can also be used as a ballast tank. When used as a ballast tank, it can be used to adjust the amount of lift of the main hull 10. Furthermore, if the hydrofoil 20 is equipped with a wing lifting mechanism 41, when the hydrofoil 20 is raised or lowered, ballast water can be injected when the hydrofoil 20 is lowered and discharged when the hydrofoil 20 is raised or lowered, thereby reducing the power required to raise and lower the hydrofoil 20.

[Steering and attitude control] Steering (speed adjustment) in the fore-and-aft direction X is mainly achieved by adjusting the thrust Ts generated by the propeller 12d, but braking forces from the flaps 20a of the hydrofoil 20, the flaps 30a of the struts 30, etc. are also used as needed.

Furthermore, steering in the left-right direction Y (maintaining course, turning, etc.) is performed using the flaps 30a of the struts 30, but if necessary, steering force from the rudder 13a is used. If multiple propellers 12d are provided in the left-right direction Y, turning force is obtained by individually controlling the thrust Ts of these propellers 12d. Furthermore, if the configuration allows the direction in which the thrust Ts of the propellers 12d is generated to be changed, turning force is obtained by changing this direction of generation. Furthermore, by tilting the hull 11 sideways, turning force can also be obtained using the lift of the hydrofoils 20.

Furthermore, for maneuvering in the vertical direction Z (depth maintenance, submersion, surfacing, etc.), lift Lu and Ld from the flaps 20a of the hydrofoils 20 are used, but if necessary, lift Lu and Ld from the submersion horizontal rudder 13b are also used. If multiple propellers 12d are provided in the vertical direction Z, the thrust Ts of these propellers 12d can be individually controlled to obtain the force for submersion or surfacing. Furthermore, if the configuration allows the direction in which the thrust Ts of the propellers 12d is generated to be changed, the force for submersion or surfacing can be obtained by changing this direction. Furthermore, if ballast tanks 15 are provided, the force for submersion or surfacing can be obtained by filling or discharging ballast water from the ballast tanks 15, etc.

Regarding heeling and rolling around the axis in the longitudinal direction X, the attitude of the ship's heeling and rolling are controlled and the reduction of rolling is controlled by fine-tuning the lift force of the flaps 20a of the hydrofoils 20 and the flaps 30a of the struts 30, respectively. Furthermore, if multiple ballast tanks 15 are provided in the transverse direction Y, these adjustments are made by filling and discharging ballast water in the ballast tanks 15, etc.

Furthermore, with regard to the vertical tilt (trim) and pitch (pitch) around the axis in the left-right direction Y, the lift forces Lu and Ld of the flaps 20a of the hydrofoils 20 arranged at a distance in the fore-aft direction X are adjusted to control the vertical tilt attitude and reduce pitching. Furthermore, if multiple ballast tanks 15 are provided in the fore-aft direction X, these adjustments are made by adjusting the inflow and outflow of ballast water from the ballast tanks 15, etc.

Sway and yaw around the vertical Z axis are reduced by individually controlling the means that generate turning forces.

[Emerged and submerged states when stationary] Next, we will explain the emerged and submerged states of this submersible hydrofoil vessel 1 when stationary. Here, as shown in Figure 4, the emerged and submerged states of this submersible hydrofoil vessel 1 when stationary are classified into "fully emerged state C0," "main hull emerged state C1," "semi-emerged state C2," "semi-submerged state C3," and "fully submerged state C4."

The "fully surfaced state C0" is a state in which the main hull 10 and hydrofoils 20, in other words, the entire submersible hydrofoil vessel 1, are surfaced above the water surface Ws0 relative to the still water surface. Normally, since the submersible hydrofoil vessel 1 has weight, it will not reach this state on its own, but rather it will be in this state when it is lifted by a crane or placed in a floating dock for maintenance or inspection, etc.

Furthermore, the "main hull surfaced state C1" is a state in which the volume of the main hull 10 floating above the water surface Ws1 relative to the still water surface is 100% of the volume of the main hull 10, and part of the strut 30 is floating above the water surface Ws1. Normally, the weight of the submersible hydrofoil vessel 1 is greater than the buoyancy of the hydrofoils 20 and struts 30, so this state will not occur on its own, but rather occurs when the vessel is lifted by a crane or the like for maintenance and inspection, etc.

Furthermore, the "semi-floated state C2" is a state in which the volume of the main hull 10 floating above the water surface Ws2 relative to the still water surface is between 50% and 100% of the volume of the main hull 10. In this state, the buoyancy of the submerged portion of the submersible hydrofoil vessel 1 is greater than the weight of the submersible hydrofoil vessel 1, and more than half of the volume of the main hull 10 is floating. This state is common on passenger ships, etc.

Furthermore, the "semi-submerged state C3" is a state in which the volume of the main hull 10 floating above the water surface Ws3 is greater than 0% and less than 50% of the volume of the main hull 10. In this state, the buoyancy of the submerged portion of the submersible hydrofoil vessel 1 is greater than the weight of the submersible hydrofoil vessel 1, but more than half of the volume of the main hull 10 is submerged. This "semi-submerged state C3" is suitable for infiltration applications where the main hull 10 needs to be kept hidden in a standby state, such as for transporting infiltrators or rescuing pilots, requiring stealth operations.

The "fully submerged state C4" is a state in which the volume of the main hull 10 floating above the water surface Ws3 is 0% of the volume of the main hull 10. In this state, the weight of the submersible hydrofoil vessel 1 is greater than the buoyancy of the submerged portion of the submersible hydrofoil vessel 1, and the entire submersible hydrofoil vessel 1 is completely submerged. This "fully submerged state C4" is also suitable for infiltration applications where the main hull 10 needs to be kept hidden while on standby, such as for covert operations such as transporting infiltrators or rescuing pilots.

[Classification of Navigation in Each State] Next, we will explain the classification of navigation in each state of this submersible hydrofoil ship 1. Navigation in each state is classified as follows, as shown in Figures 5 to 7: "Main Hull Surfaced Navigation N1," "Semi-Surfaced Navigation N2," "Semi-Submerged Navigation N3," "Sail Surfaced Navigation N4," "Periscope Depth Navigation N5," and "Fully Submerged Navigation N6." Note that Figures 6 and 7 show the lift forces Lu and Ld generated by the hydrofoils 20 when the submersible hydrofoil ship 1 is in the semi-surfaced state C2 when stopped. Therefore, the vertical direction of the lift generated by the hydrofoils 20 when the submersible hydrofoil ship 1 is not in the semi-surfaced state C2 when stopped may differ from that shown in Figures 6 and 7, depending on the surface state when stopped.

"Main hull surfaced navigation N1" as shown in Figure 6(a) is the same navigation state as a conventional hydrofoil vessel, in which the sum of the buoyancy of the submerged portions of the hydrofoils 20 and struts 30 and the upward lift force Lu of the hydrofoils 20 is large relative to the weight of the submersible hydrofoil vessel 1. In this state, the submerged portions that experience water resistance are the submerged portions of the hydrofoils 20 and struts 30. In the case of a fully submersible hydrofoil 20, the hydrofoils 20 are located at a depth where they are hardly affected by the water surface (free surface), so the propulsion resistance of the submersible hydrofoil vessel 1 is solely the resistance of the submerged portions of the hydrofoils 20 and struts 30.

The benefits of sailing with this "main hull surfaced navigation N1" are the same as those of conventional hydrofoil vessels. First, because the main hull is fully surfaced while sailing, it is possible to use internal combustion engines such as diesel engines, radio communications, radio wave equipment, and optical equipment. Also, because it propels on foils, there is less propulsive resistance, allowing for high-speed sailing, resulting in low fuel consumption and a wider sailing range. On the other hand, there is a possibility that waves will hit the bottom of the vessel in rough weather, which makes it less weather-resistant. Also, since a large portion of the vessel is exposed above water, its anti-radar and stealth capabilities are poor. As for its wake, it is smaller than a displacement-type vessel, so visibility is reduced.

"Semi-surfaced navigation N2" as shown in Figure 6(b) is a navigation state that occurs in conventional hydrofoil vessels during the surfacing and water landing processes. The sum of the buoyancy of the hydrofoils 20 and struts 30 and the upward lift force Lu of the hydrofoils 20 is small relative to the weight of the submersible hydrofoil vessel 1, and the buoyancy of the main hull 10 is also utilized, allowing the vessel to navigate with more than half of the volume of the main hull 10 afloat.

In this "semi-surfaced navigation N2," the parts that experience water resistance are the submerged portions of the hydrofoils 20 and struts 30, as well as the submerged portions of the main hull 10. Therefore, the propulsion resistance of the submersible hydrofoil vessel 1 is the resistance of the submerged portions of the hydrofoils 20 and struts 30, as well as the resistance of the submerged portions of the main hull 10. However, when an upward lift force Lu is applied to the main hull 10, the submerged volume is smaller than that of conventional displacement vessels or planing vessels, so frictional resistance due to the submerged surface area and wave-making resistance and pressure resistance due to the shape of the submerged portions are reduced.

The advantages of sailing in this "semi-surfaced navigation N2" mode are as follows: Because it is surface navigation, it is possible to use internal combustion engines such as diesel engines, radio communications, radio wave equipment, and optical equipment. Furthermore, the hydrofoils 20 allow the main hull 10 to be semi-surfaced, reducing the flooded volume and flooded surface area compared to navigation on a displacement vessel, thereby reducing wave-making resistance and frictional resistance. This allows for faster navigation and improved fuel efficiency than when the hydrofoils 20 do not provide lift Lu. Furthermore, since the height of the above-water portion is lower than in surfaced navigation N1, and the exposed area above water is smaller, radar and stealth capabilities are somewhat improved. Furthermore, the presence of submerged portions prevents waves from hitting the bottom of the main hull 10 in rough weather, somewhat improving weather resistance. However, the submerged portions of the main hull 10 leave a larger wake.

The "semi-submerged navigation N3" state shown in Figure 7(a) is a navigation state rarely seen in conventional hydrofoil vessels. In this state, the sum of the buoyancy of the hydrofoils 20 and struts 30 and the upward lift force Lu of the hydrofoils 20 is small relative to the weight of the submersible hydrofoil vessel 1. The buoyancy of the main hull 10 is also utilized to float the main hull 10, or the weight of the submersible hydrofoil vessel 1 is added to the downward lift (sinking force) Ld of the hydrofoils 20, allowing the vessel to navigate with more than half of the main hull 10's volume submerged. In this state, because more than half of the main hull 10 is submerged, propulsion resistance increases, but the floating portion is smaller, improving radar-resistant stealth and increasing secrecy. However, the portion that penetrates the water surface is larger, leaving a larger wake.

The "Sail Surfaced Navigation N4" state shown in Figure 7(b) is what is known as the "scaling" state in submarines, in which part or all of the sail 14 is surfaced. In this state, the submarine can travel by taking in and out air with the snorkel and being driven by the internal combustion engine 12a. In this state, the buoyancy of the submersible hydrofoil vessel 1 and the downward lift Ld (and in some cases the upward lift Lu) of the hydrofoils 20 are used to navigate with part or all of the sail 14 surfaced, relative to the weight of the submersible hydrofoil vessel 1. In this state, only the sail 14 is surfaced and the rest of the vessel is submerged, which increases propulsion resistance, but the surfaced portion is smaller, improving anti-radar stealth capabilities and reducing visibility due to the smaller wake.

The "periscope depth navigation N5" state shown in Figure 7(c) is what a submarine would call periscope depth, where the submarine is traveling using power from a power storage device without using a snorkel to take in or exhaust air. In this state, the sail 14 is submerged, but parts such as the periscope and communication antenna are raised as needed. In this state, the surrounding environment can be detected using the periscope or radar, or various information can be obtained through external communications. Furthermore, because the raised portion is significantly smaller, anti-radar stealth capabilities are improved, and visibility is significantly reduced because the wake is smaller.

"Fully submerged navigation N6" as shown in Figure 7(d) is what a submarine would call submerged navigation, and is a state in which the submersible hydrofoil vessel 1 travels using power from the power storage device 12c, etc. In this state, the submersible hydrofoil vessel 1 travels fully submerged, utilizing the buoyancy of the submersible hydrofoil vessel 1 and the downward lift Ld (and in some cases the upward lift Lu) of the hydrofoils 20 relative to its own weight. Being fully submerged in this state reduces wave-making resistance, but increases frictional resistance and pressure resistance, resulting in greater propulsion resistance. On the other hand, since there are no floating parts, radar-resistant stealth capabilities are ensured, and visibility is significantly reduced by almost completely eliminating the vessel's wake. Note that this submersible hydrofoil vessel 1 is not intended for long-term operation at deep depths like a submarine, but rather for short-term navigation at shallow depths of a few meters to a few tens of meters.

[Hydrofoil lifting, storage, and separation] Furthermore, the submersible hydrofoil vessel 1 can be configured with a wing lifting mechanism 41 that changes the separation distances Sf and Sa between the main hull 10 and the hydrofoils 20, as shown in Figure 8; or with a storage and deployment mechanism 42 that deploys the stored hydrofoils 20, as shown in Figure 9, while storing the hydrofoils inside or in contact with the main hull 10; or with a wing separation mechanism 43 that separates the hydrofoils 20 from the main hull 10, as shown in Figure 10, which has the following advantages.

First, the wing lifting mechanism 41 allows the hydrofoils 20 to be raised and lowered according to the water depth Sd of the navigation area by changing the separation distance Sf, Sa between the main hull 10 and the hydrofoils 20 depending on whether the vessel is surfaced or submerged, enabling safe navigation even in shallow waters. Furthermore, during main hull surfaced navigation N1, the distance Su between the main hull 10 and the water surface WL can be changed, allowing for more precise response to conditions on the water surface, such as waves.

Furthermore, as shown in Figure 9, if the vessel is equipped with a storage and deployment mechanism 42, the hydrofoils 20 can be stored during submerged navigation, reducing propulsion resistance during submerged navigation and improving propulsion efficiency. Furthermore, when it is time to surface again, the hydrofoils 20 can be deployed to allow for surface navigation.

Furthermore, as shown in Figure 10, if the submersible hydrofoil vessel 1 is equipped with a wing separation mechanism 43, the hydrofoils 20 can be separated during surfaced or submerged navigation, reducing the mass of the submersible hydrofoil vessel 1 and reducing propulsion resistance during navigation, thereby improving propulsion efficiency. However, in this case, after separation, the hydrofoils 20 cannot be used again for navigation.

The propulsion resistance of the submersible hydrofoil vessel 1 can be reduced by changing the separation distances Sf and Sa of these hydrofoils 20, or by retracting or separating them. Furthermore, it becomes possible to navigate in shallow waters. Being able to navigate in shallow waters is important for navigation in harbors, docking and landing, and landing operations. It also significantly reduces the volume required for storage and management of the submersible hydrofoil vessel 1. Therefore, even if the separation distances Sf and Sa are changed by moving only two positions, extended (foil-propelled state) and retracted (vessel bottom), it is believed that the effect will be significant.

[Submersible Hydrofoil Ship of the Second Embodiment] Next, we will explain the submersible hydrofoil ship 1A of the second embodiment of the present invention. As shown in Figure 11, this submersible hydrofoil ship 1A is configured not with fully submersible hydrofoils 20, but instead with semi-submersible hydrofoils 20A as its main hydrofoils, with part of the hydrofoil protruding above the water surface during main hull surface navigation N1. The rest of the configuration is almost the same as the submersible hydrofoil ship 1 of the first embodiment. Typically, semi-submersible hydrofoil ships, like this submersible hydrofoil ship 1A, are configured with a front semi-submersible hydrofoil 20A and a rear fully submersible hydrofoil 20, but both may be semi-submersible hydrofoils 20A, or the front and rear may be reversed.

In this semi-submersible hydrofoil vessel 1A, the semi-submersible hydrofoil 20A has stability against rolling, just like semi-submersible hydrofoil vessels of the prior art, making it easier to control. Furthermore, compared to fully submerged hydrofoil vessels, it can navigate in slightly shallower waters.

[Method for surfacing and sinking a submersible hydrofoil vessel] Next, we will explain the method for surfacing and sinking a submersible hydrofoil vessel according to an embodiment of the present invention. This method is used in a submersible hydrofoil vessel 1, 1A, which is composed of a main hull 10 and hydrofoils 20 arranged at a distance from the main hull 10. When the main hull 10 is raised from a stationary state to begin sailing, an upward lift force Lu is generated by the hydrofoils 20. When the main hull 10 is submerged from a stationary state to begin sailing, a downward lift force Ld is generated by the hydrofoils 20.

Furthermore, in the above method, when sailing, the hydrofoils 20 generate an upward lift force Lu to raise the main hull 10, or the hydrofoils 20 generate a downward lift force Ld to lower the main hull 10, thereby causing the main hull 10 to sail in one of the following states: main hull floated state C1, semi-floated state C2, semi-submerged state C3, or fully submerged state C4.

When the submersible hydrofoil vessels 1, 1A are in the semi-afloating state C2 while stopped, they can perform semi-afloating navigation N2 because they are in the semi-afloating state C2 during navigation without generating lift with the hydrofoils 20. The submersible hydrofoil vessels 1, 1A can perform main hull surface navigation N1 by generating upward lift Lu with the hydrofoils 20. The submersible hydrofoil vessels 1, 1A can also perform semi-submerged navigation N3, sail surface navigation N4, periscope depth navigation N5, and fully submerged navigation N6 by generating downward lift Ld with the hydrofoils 20.

Furthermore, when the submersible hydrofoil vessels 1, 1A are in the semi-submerged state C3 when stopped, they can perform semi-submerged navigation N3 because they are in the semi-submerged state C3 during navigation without generating lift with the hydrofoils 20. The submersible hydrofoil vessels 1, 1A can perform main hull surface navigation N1 and semi-submerged navigation N2 by generating upward lift Lu with the hydrofoils 20. Furthermore, the submersible hydrofoil vessels 1, 1A can perform sail surface navigation N4, periscope depth navigation N5, fully submerged navigation N6, etc. by generating downward lift Ld with the hydrofoils 20.

When the submersible hydrofoil vessels 1, 1A are in a fully submerged state C4 while stopped, they can perform fully submerged navigation N6 without generating lift with the hydrofoils 20. By generating upward lift Lu with the hydrofoils 20, the submersible hydrofoil vessels 1, 1A can perform periscope depth navigation N5, sail-surfaced navigation N4, semi-submerged navigation N3, semi-surfaced navigation N2, main hull-surfaced navigation N1, etc.

This method for surfacing and lowering a submersible hydrofoil vessel allows the hydrofoils 20 to generate a downward lift Ld in addition to an upward lift Lu, allowing the submersible hydrofoil vessels 1, 1A to surfacing and lowering the main hull 10 during navigation, with the main hull 10 in a fully submerged state C4 or a semi-submerged state C3. Therefore, simply by widening the angle of attack of the hydrofoils 20 or the range of motion of the flaps 20a, the submersible hydrofoil vessels 1, 1A can perform surfaced navigation N1, N2 and submerged navigation N3 to N6.

With this method, the submersible hydrofoil vessels 1, 1A do not need to take in or out ballast water from the main hull 10 to surface or sink, as is the case with submarines, and therefore do not need to be equipped with ballast tanks. Furthermore, since the submersible hydrofoil vessels 1, 1A do not dive to great depths like submarines, they do not need to be equipped with pressure hulls. This simplifies the structure of the submersible hydrofoil vessels 1, 1A.

In addition, the submersible hydrofoil vessels 1, 1A use the downward lift Ld of the hydrofoils 20 to sink the main hull 10. Therefore, if the main hull 10 has enough buoyancy to remain afloat when stopped, the submersible hydrofoil vessels 1, 1A can safely remain afloat without sinking even in the event of a malfunction of the hydrofoils 20.

Furthermore, when the submersible hydrofoil vessels 1, 1A are surfaced, ballast water is discharged from the ballast tanks 15 attached to the main hull 10, hydrofoils 20, struts 30, etc., and when the submersible hydrofoil vessels 1, 1A are submerged, ballast water is poured into the ballast tanks 15, allowing the submersible hydrofoil vessels 1, 1A to surface and sink with a smaller lift force L of the hydrofoils 20. This allows the hydrofoils 20 to be made smaller.

[Advantages of Submersible Hydrofoil Ships] Next, we will explain the uses of the above-mentioned submersible hydrofoil ships 1, 1A. The advantages of submersible hydrofoil ships 1, 1A sailing on the surface are as follows: There is reduced propulsion resistance due to a reduced flooded volume and flooded area. In addition, an internal combustion engine can be used. As a result, a long sailing distance (wide sailing range) can be achieved due to high-speed sailing and good fuel economy. Furthermore, the ability to use radio waves such as radar and communications makes it relatively easy to grasp the surrounding situation while sailing. Furthermore, the high sailing speed and smaller submerged area of sailing on the surface increase the possibility of avoiding attacks from anti-submarine weapons such as anti-submarine torpedoes, anti-submarine rockets, anti-submarine missiles, and anti-underwater depth charges.

In particular, by forming the hydrofoils 20 and struts 30 of the submersible hydrofoil vessels 1 and 1A from materials such as non-magnetic aluminum alloys, titanium alloys, carbon fiber reinforced plastics, plastic materials, etc., or stainless steel, which has lower magnetic properties than steel, it may be possible to make them compatible with magnetic fuses used in underwater attack weapons.

On the other hand, the benefits of submersible hydrofoil vessels 1 and 1A sailing submerged include reduced wave resistance due to a reduction or elimination of surface volume, and a reduced wake. This significantly reduces anti-radar stealth and visibility. It also reduces or avoids the effects of waves on the water surface in rough weather. This increases the likelihood of avoiding attacks from anti-surface weapons such as anti-ship missiles, anti-surface missiles, anti-surface rockets, anti-aircraft missiles, naval guns, anti-aircraft guns, close-in missile defense systems (CIWS), autocannons, and machine guns. In particular, it also increases the likelihood of avoiding attacks from high-energy laser systems, which have been developed in recent years.

[Uses of Submersible Hydrofoil Vessels] We will now explain the uses of submersible hydrofoil vessels 1, 1A that have these advantages. Here, we are considering uses for submersible hydrofoil vessels 1, 1A up to the size of conventional hydrofoil vessels. At this scale, possible uses include military unmanned surface and underwater drones, small attack craft, small rescue boats for rescuing pilots, small infiltration craft, and landing craft. For civilian use, the only benefit of submerged navigation is for avoiding collisions in rough weather, so there may be no uses other than as underwater tourist boats.

These military boats are launched from a mother ship or base outside the enemy's search or attack range (out-range) and travel on the surface. This allows them to travel at high speeds and gain distance. Then, within the enemy's search range, where anti-radar stealth and secrecy are required, they travel submerged. This allows them to reach target ships, surface bases, rescue areas, infiltration sites, landing sites, etc., while increasing their secrecy against radar and visual detection, and their defense against surface attack weapons. In military applications, the shape of the main hull 10, particularly the shape of the upper part, is preferably designed to provide anti-radar stealth like a cruise missile, and is also preferably designed and painted to provide low visibility.

[Unmanned Surface/Underwater Drone] Next, if the submersible hydrofoil vessels 1 and 1A are unmanned surface/underwater drones and are used for suicide missions, they will surface or submerge as necessary to enter the attack range, then submerge and collide with the target or self-destruct in the vicinity of the target. This will destroy the above- or below-water parts of the target of attack, such as surface vessels, surface bases, or surface facilities (bridge girders, piers, docks, etc.).

When used as an unmanned surface/underwater drone, the submersible hydrofoil vessels 1 and 1A have the following advantages compared to torpedoes: they can travel longer distances, are cheaper because they can use an internal combustion engine for propulsion, and can carry a larger explosive load. Furthermore, while surfaced, they can obtain information about the surroundings and target conditions through radar or visual (optical) detection or communication, and can perform surface attacks as well as underwater attacks depending on the situation. Furthermore, because they can wait on the surface or underwater, attacks can be carried out by combining a variety of functions (e.g., surface explosions, underwater explosions, acoustic deception, chaff scattering, radio wave deception using jamming signals, decoy scattering, various attack sensors, various fuses), etc.

When submersible hydrofoil vessels 1 and 1A are waiting within the attack range, they will wait in a state suited to the local conditions, such as floating with some parts surfaced or floating safely submerged underwater. However, in shallow waters near ports and harbors, they will wait by mooring with an anchor or sinking to the bottom. Furthermore, when waiting for long periods of time, it may be possible to consider using renewable energy sources such as solar energy from solar panels or energy from wave motion.

In operation, the submerged navigation will occur if enemy radar waves are detected while the submerged vessel is surfaced, or immediately before the submerged vessel reaches the effective range (approximately 1.5 km) or maximum range (approximately 5.5 km) of the target's defense system, such as the effective range (approximately 1.5 km) or maximum range (approximately 5.5 km) of the Phalanx (Close In Water Defense System: CIWS). Attacks while submerged are not necessarily effective, so attacks while surfaced may be carried out without separating the hydrofoils 20.

In addition, submersible hydrofoil vessels 1, 1A may be equipped with detachable auxiliary fuel tanks to gain distance during surface navigation. Then, during the attack phase, they may navigate using snorkeling or fully submerged navigation. If the submerged state can be maintained without the hydrofoils 20, the hydrofoils 20, struts 30, etc. may be separated to reduce propulsion resistance. Furthermore, if fully submerged navigation is performed during this attack phase, a propulsion means that does not require intake or exhaust is provided.

It is also possible to configure a portion of the main hull 10 as a suicide vehicle, similar to a torpedo, which can be launched from the main hull 10. In this case, the suicide vehicle's propulsion system can be the same as a torpedo, as it travels only short distances underwater, and a short-distance propulsion system such as a rocket propulsion system can also be used. For example, a 6 km distance at 40 knots takes about 4 minutes 52 seconds, and a 2 km distance at 40 knots takes about 1 minute 40 seconds, so it only needs to generate propulsive force for a few minutes to 10 minutes.

In this case, the remaining main hull 10 can operate as a decoy, travel on the surface to act as an acoustic jammer to avoid detection of the detached torpedoes, or be equipped with a separate suicide device and used as a suicide drone to crash into the target. These configurations allow for more complex attacks that combine surface and underwater attacks.

In addition, when unmanned surface and underwater drones are used for reconnaissance or intelligence gathering, they will perform these tasks by submerging or surfacing as necessary in the target waters. After completing their mission, they will either scuttle on the spot or navigate submerged and surfaced to return to their mother ship or base.

[Small craft] Furthermore, when submersible hydrofoil vessels 1, 1A are used as small rescue boats for rescuing pilots, it is preferable that they be manned and have rescue personnel on board to search for, protect, and care for the person to be rescued (pilot, etc.), as well as perform enemy observation, vigilance, and protection. In this case, they can quickly arrive at the pilot's distress scene at high speed, and rescue the pilot while waiting and traveling at low speed, either surfaced if secrecy is not required or submerged if secrecy is required, and then return by submerged and surfaced navigation after the rescue.

In cases where it has been confirmed that the pilot is uninjured or only slightly injured, and if it is preferable for the submersible hydrofoil vessel 1 to be as small as possible for reasons of secrecy, etc., the submersible hydrofoil vessels 1, 1A may be unmanned. In this case, it is not necessary to provide a watertight cabin in the submersible hydrofoil vessels 1, 1A; the vessels may be equipped with and transported with diving equipment for the person to be rescued. The person to be rescued may don this diving equipment and board or hold onto the submersible hydrofoil vessel 1, 1A, allowing it to navigate submerged and surfaced.

When using submersible hydrofoil vessels 1, 1A as small infiltration craft, the infiltrators disembark from submersible hydrofoil vessels 1, 1A when they reach the infiltration site submerged. After disembarking, depending on the purpose, submersible hydrofoil vessels 1, 1A are sunk and abandoned. Alternatively, submersible hydrofoil vessels 1, 1A can be used for return, waiting submerged, and once the infiltrators return and board, they will return to the mother ship or base by submerged navigation and surface navigation. Note that, if quietness is particularly important, the engine can be stopped as necessary and the vessel can be powered by a power storage device or by human power, such as rowing.

Furthermore, when submersible hydrofoil vessels 1 and 1A are used as small attack craft, they are equipped with one or more offensive weapons (torpedoes, anti-ship missiles, anti-ship rockets, anti-surface missiles, anti-surface rockets, mortars, cannons, machine guns, etc.), and as necessary, they transition to a submerged or surfaced state to attack each target with these offensive weapons. After the attack, they can then be scuttled on the spot, or navigate submerged and surfaced to return to the mother ship or base. In this case, the small attack craft may be unmanned or manned.

[Craft] Furthermore, when submersible hydrofoil vessels 1 and 1A are used as landing craft or landing warfare transport craft, the size of submersible hydrofoil vessels 1 and 1A will be as large as current large hydrofoil passenger ships (for example, overall length approximately 27 m, overall width approximately 8.5 m, depth approximately 2.6 m, gross tonnage approximately 270 tons, passenger capacity approximately 260, cruising speed of 45 knots (approximately 83 km/h), and range approximately 450 km), and combatants, combat equipment (search equipment, attack equipment, protective equipment, etc.), combat vehicles (tanks, infantry transport vehicles, self-propelled guns, etc.), etc. will be carried within the watertight compartments of the main hull.

As it is considered difficult for a landing craft (landing craft) or landing warfare transport craft of this size to navigate fully submerged (N6), the craft will be configured to navigate using snorkels until just before landing, and then, during the landing phase, the hydrofoils 20 will be detached or retracted, allowing it to navigate surfaced even in shallow waters. Furthermore, the main hull 10 will be structured to allow beaching on the shore. Also, like current landing craft, a bow ramp will be provided at the front, from which combatants and combat vehicles will disembark.

[Other Configurations] Next, several other configurations will be described. First, the thruster 12d of this submersible hydrofoil vessel 1, 1A is positioned vertically near the position of the hydrofoil 20 so that it can also be used during surface navigation. Furthermore, when the height of the hydrofoil 20 is changed or the hydrofoil 20 is separated, the thruster 12d is configured to be able to abut against or move to the vicinity of the bottom, side, or rear of the main hull 10 so that it can be used efficiently during submerged navigation.

Furthermore, when a water jet propulsion device is used as the propulsion device 12d, the suction port must be kept submerged at all times, and is therefore provided at the front or side of the hydrofoil 20, the front or side of the strut 30, or the side or bottom of the main hull 10. On the other hand, the jet port may be provided at the hydrofoil 20, the strut 30, the bottom or stern of the main hull 10, or nearby locations, and configured to be switched depending on the sailing conditions. Furthermore, the water jet propulsion device may be configured as a unit equipped with a suction port, pump, and jet port, and this unit may be provided in a movable manner.

Furthermore, the hydrofoils 20 may be arranged in three or more rows in the longitudinal direction, rather than just two rows, and may also be arranged in multiple rows in the vertical direction.

[Effect] The above-described submersible hydrofoil vessel and method for surfacing and submerging a submersible hydrofoil vessel make it possible to provide a submersible hydrofoil vessel 1, 1A with a relatively simple configuration that is capable of high-speed navigation when waves are small and that can submerge when waves are large or secrecy is required.

1 Submersible hydrofoil (fully submersible hydrofoil)
1A Submersible hydrofoil (semi-submersible hydrofoil)
10 Main hull 11 Hull section 12 Propulsion mechanism 12a Internal combustion engine 12b Power generation device 12c Power storage device 12d Propulsion device 13 Control mechanism 13a Rudder 13b Horizontal rudder for submersion 14 Sail 14a Snorkel 14b Electronic equipment 14c Optical equipment 15 Ballast tank 20 Hydrofoil 20a Flap 20A Semi-submersible hydrofoil 30 Support 30a Flap 41 Wing lifting mechanism 42 Storage and deployment mechanism 43 Wing separation mechanism C0 Fully surfaced state C1 Main hull surfaced state C2 Semi-surfaced state C3 Semi-submerged state C4 Fully submerged state N1 Main hull surfaced navigation N2 Semi-surfaced navigation N3 Semi-submerged navigation N4 Sail surfaced navigation N5 Periscope depth navigation N6 Fully submerged navigation Sa Distance Sf between the main hull and the rear hydrofoil Distance X between the main hull and the front hydrofoil Forward-backward axis Y of the submersible hydrofoil vessel Lateral axis Z of the submersible hydrofoil vessel Up-down axis of the submersible hydrofoil vessel

Claims (10)

A submersible hydrofoil vessel comprising a main hull (10) and hydrofoils (20) spaced apart from the main hull (10), characterized in that the hydrofoils (20) generate an upward lift (Lu) to raise the main hull (10) from a stationary position and operate in a manner that allows it to move forward, and the hydrofoils (20) generate a downward lift (Ld) to lower the main hull (10) from a stationary position and operate in a manner that allows it to move forward submerged. The submersible hydrofoil vessel of claim 1, characterized in that it performs surfaced navigation (N1, N2) by generating an upward lift (Lu) on the hydrofoils (20) to place the main hull (10) in a main hull surfaced state (C1) or a semi-surfaced state (C2) and sails, and performs submerged navigation (N3, N4, N5, N6) by generating a downward lift (Ld) on the hydrofoils (20) to place the main hull (10) in a fully submerged state (C4) or a semi-submerged state (C3). A submersible hydrofoil vessel as described in claim 1, characterized in that some or all of the hydrofoils (20) are fully submersible hydrofoils. A submersible hydrofoil vessel as described in claim 1, characterized in that some or all of the hydrofoils (20) are semi-submersible hydrofoils. The submersible hydrofoil vessel described in claim 1, characterized in that it is equipped with a wing lifting mechanism (41) that changes the separation distance (Sa, Sf) between the main hull (10) and the hydrofoil (20). A submersible hydrofoil vessel as described in claim 1, characterized in that it is equipped with a storage and deployment mechanism (42) for storing the hydrofoils (20) inside or in contact with the main hull (10) and deploying the stored hydrofoils (20). A submersible hydrofoil vessel as described in claim 1, characterized in that it is provided with a wing separation mechanism (43) that separates the hydrofoil (20) from the main hull (10). A method for surfacing and submerging a submersible hydrofoil vessel (1) comprising a main hull (10) and hydrofoils (20) spaced apart from the main hull (10), wherein when the main hull (10) is raised from a stationary state to sail, the hydrofoils (20) generate an upward lift force (Lu), and when the main hull (10) is submerged from a stationary state to sail, the hydrofoils (20) generate a downward lift force (Ld). A method for surfacing and submerging a submersible hydrofoil vessel as described in claim 8, characterized in that, when sailing, the hydrofoils (20) generate an upward lift (Lu) to raise the main hull (10) from a stationary state, or the hydrofoils (20) generate a downward lift (Ld) to submerge the main hull (10) from a stationary state, thereby causing the main hull (10) to sail in one of the following states: a surfaced state (C1), a semi-surfaced state (C2), a semi-submerged state (C3), or a fully submerged state (C4). A method for surfacing and submerging a submersible hydrofoil vessel as described in claim 8, characterized in that ballast water is discharged from the ballast tanks (15) when the main hull (10) is raised from a stopped state, and ballast water is poured into the ballast tanks (15) when the main hull (10) is submerged from a stopped state.