Not Applicable
This invention was not subject to any federally sponsored research or development.
In the field of ships a primary problem is that of the vessel rolling, or heeling to one side or the other, at times to the point of capsizing. Marine vessels will heel in several circumstances; due to the wind on the parts of the vessel above the water line, from wave action, from cargo that is not balanced correctly, from maneuvers, or from any combination of these factors. This places restrictions on the vessels which are not limited to reduced speed and cargo capacity, excess drag, reduced maneuverability, making for uncomfortable passengers, and in sailing vessels, limits the amount of sail that can be used. Large ships today cannot use sail power because of the heeling forces of the wind, and so must endure the costs of fuel.
This problem has been dealt with primarily by the use of gravity to balance the roll forces, in two basic ways. The first is to put weight as low as possible in the vessel, with the idea of lowering the center of gravity to keep the bottom of the vessel down. The buoyancy of the vessel, then keeps the top above the water.
The second method of reducing heel is by making the vessel very wide so that the width of the vessel provides a lever against the heeling forces, and the weight of the vessel as it heels provides the righting force, such as with a catamaran that has two hulls spaced widely apart, or a cargo ship that is made very wide.
Sailboats use aerodynamic forces—fluid dynamic forces—on their sails, on top of the boat, to power the boat. This also creates a lateral force on the sails which rolls the vessel. Ballast is used to keep the boat upright. Ballast may be fixed in position, such as with a fixed and weighted keel, or can be movable, shifting from side to side as needed. Ballast can be leveraged to some degree as with the canting keels or an extremely deep keel. The more weight in the keel, the more sail can used, and the lower the boat will sit in the water. A heavier boat takes more power to move than a lighter one. Balancing the aerodynamic forces with gravitational forces limits the amount of sail that can be used for any given circumstances, since the combination of sail and wind can still provide enough lateral force to blow the vessel over, capsizing it. As well, allowing the vessel to heel in this manner, allows the wind to be spilled from the sails and power is lost in this way.
If a vessel with a fixed and weighted keel is sitting level, then the ballast has no righting force. As the vessel heels, righting force is produced. As such, ballast is more useful when the vessel is more heeled, and less useful when the vessel is less heeled. For the ballast to have effect, these boats must be sailed off level.
Keels are also used for directional stability, as are dagger boards or lee boards, as they move very easily through the water if moved edge on, but with great difficulty when moving broadside to the water. Without these, the vessel is blown in front of the wind, and maintaining course is achieved by heading partially into the wind, so that the vessel will travel partially sideways (yaw) on its' course.
The keel has maximum effectiveness when it is vertical, as this is when it provides its' maximum face to the water and the maximum resistance to sideways movement. This is when the ballast in the keel has its minimum effectiveness as it is in the vertical line with the center of gravity of the vessel. As the boat heels, the keel rotates to a slanted position, which lifts the ballast to produce a righting force. This also allows the water an easy escape under the keel, which allows the boat to slide sideways more easily. The more effective the ballast is, the less effective the keel is for directional stability.
If a vessel, powered or sail, is level, then the vessel will move at its' optimum efficiency, as the vessels are designed symmetrically side to side, and the various forces will be the same on both sides of the vessel as it passes through the water. Unless the vessel is in the shape of a cigar, allowing it to sail off level presents a shape below the water that is not symmetrical, and one side will have more resistance to movement than the other side. Thus, the vessel will move in a circle without assistance from the rudder. When the rudder is used to keep the vessel on course, this balances the uneven resistance with more resistance in the opposite direction. One inefficiency is balanced with another inefficiency, and more power must be used to make the same speed as a similar vessel sailing level. Much of the time powered vessels are moving in fair weather where a small degree of heel, such as that caused by an uneven loading of cargo, or the wind, could increase this inefficiency considerably, raising costs in the areas of fuel economy or speed.
Maneuverability is a considerable problem. On vessels which turn by the use of the rudder, the force of the rudder on the bottom of the hull is often insufficient to cause the vessel to roll into the turn. The ship then rolls to the outside, and skids around the turn losing momentum and reducing maneuverability. Anything inside or on the ship that is not secured will also fall to the outside of the turn, sometimes causing loss, damage or injury. Securing everything before maneuvers adds costs in time, equipment and labor. In the case of large military vessels such handicaps could lessen their longevity considerably in a combat situation.
Control of roll in marine vessels by gravitational means has severe limitations. For these reasons, there is an imperative need for a definitive solution to the problem.
This invention describes a pair of opposing, independently deployable, hydrodynamic wings extending downward from the bottom of a marine vessel, of sufficient size and foil shape such that the low pressure lift created by the movement of the wing through the water will balance the roll, or heeling motion of the vessel. One wing provides the force to balance the roll to one side of the vessel. The other wing provides the force to balance the roll to the other side of the vessel. The wings are independently deployable to provide a means of adjusting the necessary control force to the conditions. The wings may be used together with one wing being more extended than the other for the added purposes of directional stability and to control leeway
Further areas of applicability will become apparent from the description provided herein, the accompanying drawings and the claims appended thereto. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present teachings.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
This invention describes a pair of opposed hydrodynamic wings which extend downward from the bottom of a marine vessel.
Referring to
The wings are made using any materials and processes that will provide the proper shape and structural strength necessary to achieve the desired results. In the first case for a small sailboat, the wings are built using alternating layers of fiberglass and plywood. Once the primary shape is made, then the wings are sanded to the finished shape, smoothed and finish coated. As a practical matter the wings should be made as large as possible. With the enormous variety of conditions that may be met on the seas, it is better to have too much roll control rather than too little.
In other embodiments, this action can be carried out using electric motors with remote controls and proper gearing for the function. In another embodiment, this function can be carried out using hydraulics and remote controls. These examples of various methods of controlling the hydrodynamic wings are not meant to limit the methods of controlling the wings in any way or to limit the scope of this invention.
The wings are independently deployable. With the extension of one wing at a time, one wing controls the roll of the vessel to one side of the vessel, as in
In the primary configuration, the wings are attached to the vessel such that they rotate longitudinally around an axis on one end, and pivot from a fully retracted position on the vessel to a fully extended position downward from the bottom of the vessel. The wings retract into a tunnel built into the hull of the vessel. There must be the capability to maintain the wings at any angle, respective to the limitations of the gearing, between fully refracted and fully extended so that the amount of righting force can be controlled. Another configuration places the wings as dagger boards, where they are movable vertically up and down, either parallel or angled laterally from the vertical longitudinal plane of the vessel. In another configuration, wings could be attached to the outside of the hull, as an appendage, without the need for a tunnel to be built into the hull.
The center of lift on a straight wing is at the center of the wing longitudinally. On a wing with a tapered end, the center of lift will move correspondingly toward the hull. The distance from the center of lift to the rotation point, is the lever arm. This distance times the lift force of the wing provides the torque to control the roll. The wings may be extended fully or partially, to provide the necessary torque to balance the roll. As the wing is extended, the center of lift extends farther below the boat, increasing the leverage.
As speed increases, the lift force increases, until the wing reaches its' maximum design speed. Above the design speed the wing loses efficiency as excessive turbulence appears on the rear part of the wing, as the fluid flow detaches from the surface of the wing. To alleviate this problem, the wing is then retracted partially. This effectively elongates the foil shape of the wing, with respect to the water passing over it, which allows the fluid flow to stay attached to the wing longer, and thus reduces the turbulence on the back part of the wing. In this mode the wing will provide the necessary lift, as speed increases, over a much wider range of speeds, than it can if just extended fully, or if they are extended dagger board fashion.
This boat will be sailed differently than a conventional sailboat. With a conventional ballasted sailboat, no matter what the situation is, you have the ballast pulling the bottom of the boat down, which maintains stability in any situation up to the limits of the ballast. With this design, roll control is only available while the boat is moving and increases with speed. Therefore the boat must have sufficient stability when stopped, or at very low speeds not to capsize. Also, just as airplanes take off and land into the wind as much as possible, so this design will benefit from heading into the current during low speeds. Then as the speed increases the effect of the current lessens.
In the primary configuration, one wing is extended to control the roll as shown in
The lesser extended wing may in this case cause the boat to turn, due to the wing being extended towards the stern of the boat, and its center of lift and lever arm being some distance behind the rotation point of the wing. For this reason the connection point of the wings can be in front of the center of lateral resistance, as the center of lift of the two wings will then tend to balance each other, and any residual yaw effect can be managed with the rudder.
The wings may be positioned side by side, or they may be separated laterally at any degree up to 180 degrees, as long as the wings remain immersed in the water. If the wings are separated as shown in
Winged vessels combined with a planing hull will easily plane the surface of the water. By doing this the bow wave associated with displacement vessels and the corresponding pressure wave which builds in front of the boat can be nearly eliminated. As the vessel displaces less and less water, more of its' power goes to speed the boat, leaving the only drag as the drag caused by the wings in the water, the rudder and the drag caused by the air. As speeds several times the speed of the wind are being attained by land sailing vessels, there is little reason why these speeds cannot be attained on water. The idea here is for the boat to lift enough so that the bottom of the hull just skims across the surface of the water. By skimming the water, the length of the hull acts to control the pitch of the vessel (up and down movement fore and aft).
With this configuration, it becomes possible to raise the vessel completely out of the water, and to fly the vessel. If the vessel is raised above the surface of the water, then a method of controlling pitch is necessary. This can be accomplished using an inverted ‘T’ with the horizontal part being a foil, adjustable to provide the necessary pitch control. This can be affixed to the bottom of the rudder or by other means that would provide the necessary control.
Hydrodynamic wings can offer superior roll control over gravity based balancing systems. The fluid dynamic lift forces of the wings are variable as needed by the vessel by their extension and retraction. Wings can be sized and shaped to provide several times the righting forces available from gravity based systems with only a small percentage of the weight and drag penalties. This means that for sailing vessels, more sail and more powerful sails can be used. As the righting force increases with speed, the vessel can sail with more wind. Theoretically there is no limit to the size of the hydrodynamic wings, and therefore no limit to the amount of sail that can be used, until the limit of pitch control is reached. As such these vessels can be sailed in more extreme conditions than ballasted vessels can.
Wings can provide righting power ‘on demand’ regardless of the angle of heel. This will allow winged vessels to sail completely level, and as efficiently as possible. The excessive drag caused by the boat sailing off level, is traded for the drag of the wing, which is considerably less. In the case of a large ship, the ability to level the ship in this manner can amount to a savings in fuel, an increase in speed or both. By using wings on large ships, sail power can be used, which can create more savings in fuel costs.
Wings can provide the roll control necessary for vessels to turn at much higher speeds than ballasted vessels. Sail boats, powered boats and ships can be made to roll into the turns so that cargoes, crew and everything else on the vessel will stay in position, rather than the present situation where the top part of the vessel rolls to the outside of the turn and everything on the vessel that is not tied down is cast to the outside of the turn and sometimes into the sea. By rolling into the turns, vessels can maintain momentum and keep a much higher level of maneuverability, which for military vessels could be a decisive factor in their longevity. In the event of a cargo ship, where the cargo is not loaded evenly or shifts position while at sea. The wings can be deployed to bring the ship back to level, or if necessary to sail the ship off level to keep the cargo from shifting more. In the event of a military ship that was hit at or below the water line, there is the possibility that the vessel could be heeled as needed to keep the hole above water, and keep the ship afloat.
By coordinating the extension of the wings with the rolling motions of the sea, vessels can be made to eliminate the rolling motion that causes seasickness.
Number | Date | Country | |
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61378919 | Aug 2010 | US |