GB2222390A

GB2222390A - Submersible craft

Info

Publication number: GB2222390A
Application number: GB8919751A
Authority: GB
Inventors: Karl Heinz Lipschutz
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-09-02
Filing date: 1989-08-31
Publication date: 1990-03-07
Anticipated expiration: 2009-08-31
Also published as: GB2222390B; GB8919751D0; GB8821873D0

Abstract

A submarine craft comprises a high lift module with a hull containing an array of inflatable buoyancy bags 16. When submerged, water enters the hull to fill spaces between the bags 18. The dry mass of the high lift module is significantly less than the mass of the maximum displacement volume when the craft is submerged and all the bags 16 are inflated, so that the lift module can carry a heavy payload. The lift may be boosted by means of flaps 11 or 12 containing buoyancy gas provided directly on the hull or on outriggers which also mount propulsion units 4. The craft may be driven over ground or the sea bed on retractible wheels 6. Magnetic couplings 7 are provided for the releasable attachment of a nose/crew module 14 and a power/propulsion unit 15 to the craft. A submersible lifting device, Fig 5, and a light weight composite material are also disclosed. <IMAGE>

Description

Submersible Craft This invention relates to submersible craft.

It is, as a rule, uneconomic to operate and produce equipment, motorcars, planes, ships or submarines, which have been designed incorporating features and facilities which are in exccess of normal requirements.

Thus, cars and public buses are normally produced with a limited speed range which is considerably below that of racing cars; and the number of aircraft in general use which are pressurized is exceeded by the number of aircraft which are not designed for such operation, as for instance club planes, nearly all helicopters, and of course agricultural planes, since these are all normally not operated above 3000 meters, at which altitude pressurization would be an advantage or even a necessity.

For aircraft, in addition, there would be a weight penalty, since the requirement of pressurization would necessitate a stronger fuselage and hence would lead to a greater weight. This in turn would reduce its payload, and/or range, as well as rate of climb.

In the case of submarines, i.e. craft designed to be operated mainly submerged, it would be equally uneconomic to design for a depth capability which would exceed the maximum depth at which the craft was intended to be operated, or which exceeded the max. ocean depth existing in its planned operational region, since, with a given total amount of buoyancy and/or dynamic lift capability, any unnecessary added weight would, as in aircraft or balloons, reduce its payload, operational capability and flexibility.

As the design of the 'U-Plane' makes possible operation down to the bottom of any ocean, it is to be expected that this will lead to greater future activity on the seabed, especially for civil purposes, such as exploration for oil and minerals, and their subsequent commercial exploitation, especially first from the ocean shelves, and later from even greater depth down to the bottom of any ocean, anywhere.

This also leads to a requirement for underwater craft specialized or particularly efficient at underwater transport and lifting of heavy loads which may not always be designed to incorporate their own buoyancy equipment and hence may have a large negative buoyancy, thus requiring great lifting power or an excess of positive buoyancy, available or capable to be generated, and utilized for this purpose by a carrier.

A further need exists for craft able to perform rescue missions which may also involve heavy lifting, such as the rescue and recovery of 'U-Planes' whose buoyancy equipment or propulsion may have developed a fault, and hence the disabled craft is left stranded on the seabed.

For such activity a good lift-to-weight ratio of the craft is an advantage, and any weight penalty due to unnecessary features, such as a depth capability in excess of requirements which would lead to excessive strength requirements to protect against the ambient water pressure, and hence extra weight, must be avoided.

Savings in weight can be achieved by introducing a design of submarine craft especially aimed at an operational working depth mainly between 1000 meters and approx. 6000 meters, but also including good stability when at the surface. A craft limited to this depth can be constructed with a design especially aimed at this particular operational niche, and it is the purpose of this invention to provide such a craft.

Experience with conventional submersibles i.e. those with inherent positive buoyancy, has shown that this positive buoyancy should amount to approx. 20% of its design weight in order to provide a reasonable margin of positive buoyancy when surfaced. This requirement however also limits its weight and hence strength of its hull to withstand the crushing pressure of the ambient water at depth, and it is thus limited to a depth not exceeding approx. 1000 meters.

Reducing its inherent positive buoyancy to a few percent only, i.e. maintaining its displacement but increasing its weight and hence strength, its max. depth can be increased. It also follows that its ballast tanks can likewise be reduced in size and volume, since less ballast water needs now to be taken on board for a dive from the surface.

Yet in order tp remain surface-capable as before, the reduction and hence resulting insufficiency of inherent positive buoyancy should preferably be compensated for and enhanced by such means as have been described and disclosed in my recently granted patent for the 'U-Plane'. Hence it would be advantageous to apply and adapt such buoyancy control also to inherently positively buoyant submersible craft. And since its inherent positive buoyancy, although reduced, still exists, it is possible to provide a greater amount of total positive buoyancy, as and when required, additionally also when submerged, and utilize this extra available buoyancy for the purpose of lifting and subsequent recovery of objects and loads from below.

Thus, such means of compensation can be utilized to enhance the positive buoyancy of submersibles which are designed with some inherent positive buoyancy but which could or would profit from an increase of positive buoyancy when operated at the surface and at such times when this would be desirable also at any depth, for instance when employed to lift some non-buoyant object from the sea-bed and transport it elsewhere.

According to one aspect of this invention there is provided a submersible craft comprising a hull member containing a plurality of inflatable buoyancy members, inflation means for inflating said buoyancy members, and control means for controlling said inflation means, wherein, when said craft is submersed1 water enters the hull to fill at least some of the spaces between or in said buoyancy members. Said control means is preferably operable to control the inflation pressure within said buoyancy members in response to the ambient hydrostatic pressure, thereby to limit the differential pressure acting on the walls of the buoyancy member.

The dry mass of the craft is preferably substantially less than the mass of the maximum displacement volume of the craft when submerged (e.g. a ratio of 1:3 or less) whereby said submersible craft is capable of providing a considerable lift force.

The plurality of buoyancy members may comprise a regular array of inflatable cylindrical bags or an array of buoyancy cells open adjacent their lower ends, which may be inflated by the introduction of air to define buoyancy members.

The hull member may include releasable engagement means whereby the craft may be connected to another craft in modular fashion and the releasable engagement means may comprise a magnetic or electro-magnetic coupling. The craft tray include an acquisition control system for guiding relative engagement movement of said craft with another craft.

The craft may include buoyancy boost means for providing additional buoyancy, said buoyancy boost means comprising a flap or bag deployable adjacent the outer surface of the hull for receiving gas from a gas source, e.g. a row of doors provided along each side of the hull member, each openable in gull-wing fashion to contain a volume of gas.

The craft may include twin outriggers spaced one from each side of the hull each of which may include buoyancy means of the type described herein.

The craft may include a downwardly extending frame assembly for supporting the craft off the ground or sea floor and the frame assembly may be stowed in compact form, whilst still functioning as an undercarriage.

According to another aspect of this invention, there is provided a submersible lifting device, for example for recovering objects from the sea floor, comprising a base having means for attachment to an object to be lifted, a buoyancy bag connected to said base by a line, means for paying out or winching in said line, and means for introducing a volume of fluid into said buoyancy bag partially to inflate said bag to impart in use an upward thrust to said bag.

According to another aspect of this invention, thereis provided a method of recovering object from a depth of water, which comprises attaching said object to the base of a lifting device as previously defined, partially inflating said buoyancy bag, paying out said line to allow said buoyancy bag to ascend relative to said base, whereby the hydrostatic pressure acting on said bag decreases with a consequent further expansion of said bag and an increase in the buoyancy force experienced by said bag, until said buoyancy force is enough to lift said object and thereafter winching in said line to lift said object.

The invention also extends to a submersible structure comprising a submersible craft as previously defined assembled with at least one further module such as for example, one or more of a crew module, a propulsion module, or a lifting module.

According to another aspect of this invention, there is provided a submersible craft comprising a hull and buoyancy boost means deployable externally adjacent said hull for receiving a volume of gas to impart a buoyancy thrust.

According to an aspect of this invention, there is provided a submersible structure comprising a plurality of interconnected modules each including complementary engagement means and one or more of said modules may include acquisition and guidance means for guiding the module into engagement with another, and remote control, with feedback, of its operational functions and systems.

According to another aspect of this invention, there is provided a concrete or similar material containing a plurality of relatively light weight and airtight capsules, e.g. of glass.

Preferred embodiments of the invention provide means for buoyancy manipulation and control for provision of additional buoyancy for underwater craft, but of all types, thus including also those underwater craft which are inherently positively buoyant,- regardless of whether this positive buoyancy is only minute or large, - such means to be in addition to any ballast tanks provided; or by adaptation of such lightweight secondary enclosures to also be able to function both as ballast tank and provider of additional positive buoyancy, by providing known means to permit some of the gas in the secondary enclosures to be dumped, or pumped into a self-contained reservoir and allow water from the outside to enter the thus vacated space, or else provide means for pumping water for the purpose of ballast into the secondary enclosures against the pressure of the therein enclosed fluid in the form of gas, gas and water or any other kind of liquid, with provision to reverse this process when required.

Alternatively, a flexible membrane may be provided to separate the water (or any other kind of liquid) introduced as ballast from the rest of the contents of the enclosure. Yet another feature can be the provision of a separate flexible kind of 'inner balloon or tube' within the confines of the secondary enclosure, for the containment of any liquid utilized for the purpose of ballast; - a design which would be similar to the fitting of a smallish, water-filled, inner tube inside a basically tubeless car tyre filled with air under pressure in the vacant space not occupied by the smaller inner tube.

As the total buoyancy of such a craft, i.e. inclusive the additional buoyancy provided by the secondary enclosures, can be designed to vary across an enormous buoyancy range, from negative to highly positive, such a craft is best described as a 'Trans-Buoyant Submarine Craft '.

A new feature particularly useful for the purpose of increasing the positive buoyancy of this 'trans-buoyant submarine craft' and forming the following embodiment of the invention, is best described as a 'buoyancy flap', analogous in function to the 'landing flap' as used in aviation where however its main purpose is to increase the lift of its wing(s) rather than increase buoyancy.

This consists of panels which, when retracted, lie flush or are faired-in against the outer skin of the hull of the submarine, or else form part of the outer skin, and can be extended outwards and upwards pivoting at their upper edge along a substantially horizontal water-tight hinge or joint located along the side of the hull.

When seen from front or rear the movement would be similar to the extending and partial raising of its wings by a bird with the wing tip feathers still pointing relatively downward. Or else it might look like a person holding some bags between his sidewards extended arms and his body while also carrying suitcases in his hands.

When extended, like a half-opened umbrella, a space is formed in between the panel(s) forming the flap on each side of and extending from the hull, and the hull itself in the middle, and, in order to function as an enclosure, the forward and rear end of the flap is sealed by a flexible, or inward-folding stiff panel. Thus the enclosure so formed is only open at its bottom, and can be filled with air or gas, which will remain trapped inside similar to air or gas remaining inside the confines of a diving bell.

The extendable panel(s) of the buoyancy flap may also consist of hinged sections, which, when retracted, fold inwards and up, like the arms of a person with his elbows pointing downwards while the lower arms are folded upwards and each hand is tucked into the armpit on its own side.

Each flap may extend a substantial length along each side of the hull, but preferably is in sections, so that damage to one flap section does not effect all the others. It also permits extension of only a limited number of individual sections.

In order to prevent spillage between the flap-sections, the forward and rear end of each flap-section is sealed by a flexible, or inward- folding stiff panel as is provided at the outer ends of the first and last section, and each section may be further thus compartmentalized, for safety. Also the middle sections may be of somewhat larger size, and hence able to confine a larger volume of gas, than those fitted at the front and rear of the hull.

In order to prevent spillage of gas when the craft is rolling in a bad sea state, it is advantageous to provide a means for closing off the lower end of the diving-bell-like enclosures by means of flexible, but preferably not elastic sheets or-panels, or a kind of stiff panel hinged so as to permit upward movement of the hinge and thus inward and upward folding of the panel(s) when the flap is retracted. Straps of high tensile strength may be incorporated along or interwoven with any elastic sheet running in the outward direction from the hull to the lower edge of each outer flap-panel in order to prevent excessive extension and upward movement of the flap beyond its design limits.

Dumping of gas from the type of buoyancy flap which is open at its bottom will take place automatically when the flap is being retracted, and the gas is simply squeezed out downward. However, when the gas is intended to be re-used, it can be pumped into an on-board reservoir or known storage system, or system from which it originated. This permits extension of the buoyancy flap also when submerged, and its filling with gas through known valved means with gas from an on-board storage system. When surfaced or near the surface, air can be drawn from above via a schnorkel tube and pumped by means of a blower into the space formed by the extended flap.

Fully enclosed flaps, i.e. those with bottom panels, require the fitting of automatic or controlled valved means both for filling and emptying of this buoyancy system, and permit filling to a pressure in excess of ambient pressure, up to the design limits of the system.

For reduced creation and contribution to the total of positive buoyancy, it is possible to extend the buoyancy flap only partially, or extend and fill with gas only a limited number of sections. Extension can also be effected as an automatic consequence of introducing gas into the space between the hull and the flap (sections), when the flap itself will extend to a value which balances the internal with the ambient pressure until full extension. Further introduction of gas thereafter will result in the gas spilling out below the lower edge of the flap, or, in the case of the fully enclosed version, will increase internal pressure up to the limit set by known means of safety valves, computer restrictions etc., which normally would be set according to the design limit of the flap and this buoyancy system.However, since normally at no time would there be a compression load upon the flap, its installed weight can be kept low, yet its contribution of positive buoyancy to the total buoyancy of the craft can be very high.

This can further be increased by fitting an internal balloon or inner tube inside the space created by extension of the buoyancy flap, made from elastic, or flexible material, which can be inflated to fill all the space available up to full extension of the flap, and which, upon introduction of more gas, can protrude and extend beyond the lower rim of the extended flap, thus increasing by means of this gas bubble the total displacement of the buoyancy flap. The downward and outward extend of this gas bubble can be limited by means of the bottom panel sheet which can be made from flexible sheeting such as high tensile plastic, which allows bulging out to a limited degree, while also limiting the degree of flap extension outward. This is also normally limited by the panels forming the end of each flap section. Or else, the inflation-pressure can be limited to a safe value.

In order to accomodate the inner tube or internal balloon without damage to it when the flap is retracted, a suitable pit or concavity is provided at the relevant location in the wall of the hull where it is met by the retracted flap. Alternatively the inner tube may be stuck adhesively to the inner side of the flap as well as the hull and made to function also as an additional gas seal.

An alternative method of containment of gas for the purpose of additional positive buoyancy can be the use of a buoyancy flap based upon the design of a jalousie or sun shades as used by shops, and mounted as protection over their display windows.

These normally consist of a fabric sheet wound onto a long horizontally mounted rotatable tube, and unrolled while being pulled down and stretched tight by means of a folding frame on each side, thus capable of being extended, and is well known.

When fitted with flexible sealed side panels, and a suitable gas seal at its upper horizontal tube, such an arrangement can be adapted to function as an extensible buoyancy flap system operating on the principle of the diving bell, when rolled down, and thus may form another ertbodiment of the inveI oT..

an Nature the 'Trans-Buoyant Submarine Craft' would correspond to a hypothetical, normally (but not always) inherently positively buoyant penguin with an optional ballast tank and an oversized swim-bladder, and the capability to select and maintain negative, neutral or positive buoyancy at any desired depth when unencumbered, but also, having picked up a stone or heavy object, can compensates for this extra weight and its now temporary negative buoyancy by means of a vertical component of propulsion force (i.e. by powerful flapping of its wings/flippers or tail), by adjusting and increasing the displacement of its swim-bladder, or by a combination of both these methods in any suitable proportion.

For specialized craft, i.e. 'Heavy U-Lifters', (short for 'Undersea- Lifters') designed for recovery of objects from the bottom of the sea, the configuration of helicopters, tilt-rotor or tilt-wing/tilt-rotor is preferable, also the provision of a four-(or more)-legged undercarriage similar to container-carriers at harbour terminals, with the legs foldable or retractable, and tipped with wheels, bogies or tracks.

For the recovery of purpose-built containers - e.g. as for the collection of minerals or any cargo,- which can be straddled by the craft by positioning itself above the container, special hooks and grapplers can be provided at its underside and between its legs to attach such containers to itself for transport to the surface. Alternatively a second (i.e. false) bottom in the form of a platform or loading tray may be incorporated below the craft between its legs, flush and streamlined when elevated and retracted, which can be lowered to the ground, and onto which self-propelled wheeled or tracked containers (or similarly equipped modules), or also 'U-Planes, can mount from the ground nearby, to be thus carried and transported by the craft.

This facility of entering and leaving independently by such self-propelled modules when on the seabed or else on the beach at any time by rolling on or off can also be extended to be available when the 'U-Lifter' is hovering stationary or moving at a suitable, normally low speed, at any suitable depth.

Further, larger types of 'Heavy U-Lifters' can also be equipped with more than one such preferably retractable platform, with carrying capacity accordingly increased to more than one module, container, or cargo item.

In order to assist with the lifting, such containers, apart from being fitted with wheels or tracks for movement along the ground when pulled or when self-propelled, these can be fitted with their own individual means for provision of neutral or positive buoyancy and their control; or such control can be overridden and exercised by remote control or automatic means, which, for instance, can be actuated when the container is being attached to the lifter.

Pallets, for the support of sealed enclosures, or for loads not sensitive to high ambient pressure, such as tools, or open pipes for oil drilling, etc., can be wheeled or tracked, and may also be self-propelled and incorporate self-contained buoyancy equipment capable to confer neutral or positive buoyancy-to the pallet, whatever its individual inherent buoyancy, or combined buoyancy when loaded with any type of cargo, and thus heavy.

Big differentials in AUW (All Up Weight) due to possible variations in the weight of cargos, and whether empty or loaded, may exist, and hence it is advisable to incorporate buoyancy equipment of sufficient capacity to be able to compensate for insufficiency of positive buoyancy not only of the container when empty but also when loaded with cargo of any specific gravity.

This makes it possible to cope with wide variations in buoyancy requirement of the craft or enclosure, as well as permitting the selection of a high value of positive buoyancy for the purpose of lifting and raising large loads by means of buoyancy alone, or supply a substantial proportion of lifting force when in combination with dynamic means such as rotary wings, flapping wings, or a vertical component of fixed wings, jet thrust, shrouded propellor, flapping tail, or any other know means.

When a surface ship is being loaded with cargo, it merely sinks deeper into the water and then proceeds on its way with an increased draught, thus displacing more water and so compensating automatically for the increased AUW. However, when a submarine craft which is already at a neutral buoyancy with a given payload and at a given weight is loaded with additional cargo and thus its AUW is thus also increased, its displacement cannot increase merely by sinking deeper into the water and thus compensate for the greater AUW. Instead the neutral buoyancy of the submarine is now changed to negative by the amount equal to the increase in weight of the greater cargo or payload, and the craft will sink unless the increase in weight of its payload is compensated for by a matching increase in displacement and hence positive contribution of buoyancy.

In a trans-buoyant submarine craft equipped with ballast tanks of reduced size and volume, or none at all, and the weightallowance normally reserved for the conventially required ballast is reduced or completely eliminated, this weightallowance then becomes becomes available for other uses, and can be translated into stronger walls for enclosures and containers, thus permitting a greater depth to be reached safely, larger and more comfortable crew quarters as well as space for passengers, stronger motors, or a larcer battery capacity - leading to a greater underwater range.

This makes possible submerged non-stop crossing of the Atlantic, and thus removes the need for surfacing for the essential charging of batteries normally required by diesel-electric submarines. This not only removes the risk always associated with surfacing, but also removes the need for Diesel engines and all the equipment required for self-contained charging, and hence increases further the weight-allowance available for more improvements in the a.m. items, for which it can be utilized in any desired proportion.

A short list of modules illustrating some of the types which can be utilized for modular construction, may include: Manned control module (choice of sizes / choice of max. depth) Life support/First Aid module Robot (computerized) control module Power module (Battery charger,electric/hydraulic/pneumatic-power) Spare gas module (e.g. gas store, or gas generator for splitting ambient water into Hydrogen and Oxygen, electro-chemically) Extra buoyancy module Propulsion module Tractor/tug module Trailer module Cargo/container module Communication module Hotel and Recreation module Multi-docking module Exploration module Military equipment module All these modules would be equipped with individual remote-control facilities for over-riding of any computerized pre-set control by means of a signal from a crew module.

his makes it possible to replace an unmanned control module (with computerized, pre-set or remote control) by a positively buoyant crew module designed for descent to only a limited depth, or by a neutrally or negatively buoyant crew module designed for any depth up to its design limit.

Such a crew module may be wheeled, tracked and self-propelled, so that it can position itself upon the lowered loading platform or loading tray of a 'U-Lifter', and from this position control not only the lifter but also, especially when landed on the seabed, take control of all remotely controlled modules, self-propelled containers and pal lets on the seabed. Alternatively this crew module may also be attached to or form part of the assembly of a 'U-Plane' positioned upon, but capable of leaving and returning to, the loading platform of the 'U-Lifter'.

Each module, - whatever the state or sign of its inherent buoyancy - may be individually equipped with buoyancy gear as described above and in my 'U-Plane' Patent, and/or wheels, bogies, tracks, propulsive power (incl. power supply) for ground taxying and/or waterborne movement, with remote control equipment, and/or docking and connecting facilities to each other and any group forming an assembly of whatever degree of combined buoyancy. Or else several modules may be arrangeto form a pair or group, and share one common buoyancy and propulsion system.

Thus one fundamental aspect of this invention is the creation of a trans-buoyant, pre-assembled and firmly attached assembly of components, enclosures, or modules, of combined positive, neutral or negative buoyancy, also including a secondary means of ballast and/or positive bouyancy contributing enclosures and/or means for production of dynamic lift, which can be arranged to form a single hull, or a multi-hulled configuration, with the hulls attached to each other side-by-side, or connected by any number of wings, or vertically stacked, or both configurations combined.

Yet another embodiment of the invention is the creation of a family of individual modules including robotic or manned control moduls, with means of interchange and the facility to form any combination of assemblies as part of an underwater craft, linked through control by any known method, including optical, sound, radio, which may also include electrical/mechanical means when physically attached/connected to each other or the control module, or when stationed on the transport- or loading platform of a 'Heavy U-Lifter'; and permitting limitless permutations of features incl. remote control from distant, local, or attached and locked-on position, as well as permitting its assembly by remote-control not only on land but also under water, on the seabed, to any configuration which is required or desired, for exploration or commercial exploitation of resources of, and under, the seabed, at any depth and location, as well as control of 'Inner Space'.

Another embodiment is the self-contained attachable BUOYANCY UNIT (incorporating rigid, semi-rigid, or flexible displacement vessels or enclosures, gas generator or gas supply, pressure control, buoyancy sensor, ambient pressure sensor, computor, and remote control for override of pre-set functions, optional fluid-pump and power supply, etc.) which can, like an aqualung worn by a scuba diver, be attached to any component, enclosure, pallet or body, whether empty or loaded with cargo, of whatever inherent buoyancy, thereby converting this,- or indeed anything to which it is attached,- into a trans-buoyant submarine craft whose buoyancy can be pre-set, or controlled remotely to adjust to any desired value, for use at any ocean depth within the limits of its design.

In order to lighten the walls of enclosures which have to be constructed to withstand high differential pressure between their inside and ambient pressure, such walls can be made from a sandwich material, in which sealed hollow spheres or beads, made from any suitable material, including glass, etc.,empty, or filled with any suitable gas under pressure, (preferably with a gas such as helium or hydrogen), or tubular fibers, empty or gas-filled under pressure, are embedded in another material such as plastic, or a concrete mix made from special, waterproof cement. Such reinforced material will then exhibit a lower specific gravity than the matrix material on its own, but will be highly crush resistant.

Such lightweight material with high compressibility strength, is produced by inclusion of gas-filled lightweight glassfibers and/or gas-filled beads or else a string of linked spheres or short,tubes not unlike a string of small sausages, embedded as a reinforement and reducer of the normal specific weight and density of a plastic or concrete matrix by mixing into the material before casting and hardening; or by -weaving into a cloth-like sheet which is passed through an adhesive binder and atrough filled with plastic material or concrete in its pliable or semi-liquid state and then wound onto a former so to produce a cylinder or large-diameter multi-layered tube or pipe prior to setting and hardening of the material in the normal known way.

Small-sized spheres or beads can also be pre-mixed with the matrix material of any suitable kind, and then sprayed onto a rotating former, as is known in the plastic industry for the production of GRP with random reinforcement.

Tubes, pipes, cylinders or enclosures thus formed can be further strengthened by such a material being used as filler, sandwiched between an inner and outer sheet of any other suitable material such as aluminium, steel, titanium, carbonfiber reinforced plastic, or material such as kevlar.

Another option is shaping or forming of this filler material into a honeycomb shape for use as the inner filling of a sandwich forming the wall of the pressure-resisting crush-proof vessel or enclosure.

Such material can also be produced in the form of blocks of any shape, cubes, discs, spheres, closed pipes, or outer layer sprayed-on thickly or glued on to the outside of, for instance, motor casings, and components, and can be used to act as a solid enhancer of positive buoyancy where required. The material can also be formed or cast into any odd shapes for insertion as a filler of any nook and cranny, i.e. any unoccupied crevices in between modules when these are attached or docked to each other, to keep out the ambient water without having to strengthen the walls of such space against the ambient water pressure.

Alternatively a cheap but hard material as for instance glass can be utilized in form of a foam, similar to the plastic foam as used for heat insulation, with closed cellular structure, which has high. compressibility strength. This can further be increased by producing this glass foam in conditions of high ambient pressure, preferably in an atmosphere of helium or any other gas of light weight, in order to pre-stress the internal cellular structure of the foam during manufacture against compression stresses. Such foam can then be used directly as a means of permanent positive buoyancy, or can be used as an inner layer in form of a thin flat sheet, or in form of a honeycomb as the internal sandwich material between outer sheets of plastic or any other suitable material, for use as construction material for the walls of pressure-resistant sealed enclosures.

A specific embodiment of the invention, representing a specialized lifting module, will now be described by way of example with reference to the accompanying drawing in which: Figure 1 shows a head-on view of the craft, on land, prior to entering the water.

Figure 2 shows a side-on view of the craft, on firm ground; showing its starboard side.

Figure 3 shows a view as seen from above; in section.

An alternative design option for the center-body is shown in: Figure 4 showing a head-on view; in section; and Figure 5 shows a view of a Self-contained Attachable Buoyancy Unit, attached to a non-buoyant load; in section.

Referring to Fig 1, the craft comprises a lightweight center section 1 (otherwise referred to as a Hull member), to which on either side are permanently attached, by means of a wing 2 and struts 3 propulsion units 4, both containing, within a lightweight shell vented at or near its bottom, pressureresisting internal components, such as: Motors and fuel supply or batteries normally sufficient for attitude control, contribution of lift, and shortrange travel when water-borne by means of moveable jet nozzles 5, and when on the ground or seabed, movement by means of driven wheels or tracks 6, shown extended on its port side and retracted on its starboard side.

When retracted the bogies or wheel-axles are designed to rest against resilient supports capable to take the full weight of the module, and when so retracted, to maintain height from the ground of the front and rear of the module such that other wheeled or tracked modules can be docked to its front or rear by means of the magnetic docking buffers 7.

The light-weight outer shell of the center section 1 is subdivided by means of bulkheads in the form of frames into a number of separate compartments which each contain and maintain in their relative location any number of sausageshaped elastic or flexible inflatable bags 16 (shown in Fig 3), which can individually be inflated or deflated, to a preset and safe level.

In order to prevent excessive pressure built-up across the walls of the outer shell, ports 8 are provided at or near its bottom and near its ceiling, with valved means to permit a small pressure difference to exist up to the design limits of the outer lightweight shell.

This is to ensure a comparable degree of expansion of any of the inflated bags within the compartments of the outer shell when the craft is at an angle of inclination in the water, and in order to prevent constant hunting i.e. cycling of the inflating system trying to adjust the gas pressure of any of the inflated bags to an ambient pressure which is fluctuating slightly, for instance when small changes of depth occur repeatedly while essentially on a level cruise.

Any bags which are inflated are normally inflated to a pressure which is nominally equal to the ambient pressure, plus a slight additional pressure in order to overcome the normal contracting tension of the elastic or flexible bag material as well as to provide a measure of stiffness to the inflated bags in order to prevent excessive deformation under mechanical stress during normal operation.

The pressure-resisting gas store 17 (Fig 3) or gas generator with its power supply is enclosed within the lightweight, vented, dorsal fin 9, running along the length on top of the center section. This also encloses at its front and rear a pressure-resisting compartment 10 for a sonar, optical or radio control unit for communication with, and control of, other, optional, docked modules, and other craft.

The walls of this pressure-resisting compartment 10 are preferably constructed from a material such as plastic or concrete which is reinforced or impregnated with hollow or gas-filled fibers of tubular shape or shaped like a row of sausages or spheres, made from glass, ceramic or any other material known to have great resistance to compressive stresses. Thus the resulting material combines high strength against crushing pressures while yet exhibiting a low specific weight, and hence confers these properties to any enclosure made from it, thereby contributing little, if any, negative buoyancy to the craft.

The shell of the center section 1 and the shells of both attached outrigger propulsion units 4 are equipped with buoyancy flaps shown on the starboard side of the craft in the retracted position and on the port side in the extended position. The flaps on the center section are of the rigid type 11, and are mounted on both sides of the shell, while those on the propulsion units are mounted on the offsides of the propulsion units only, and are of the jalousy type 12, with the 'roll-up' shaft on which the flexible sheet is wound during retraction of the flap mounted along the lower rim of each flap section, while the other, upper end of each flexible sheet is attached gas-tight to the shell along its upper length. When extended, these flaps are capable to contribute yet more positive buoyancy to the craft.

Between its undercarriage legs is slung an optional load 13, for example a 'U-Plane'.

In Fig. 2 can be seen the line of the dorsal ports 8 on the center section. Also seen are the upper parts of the outer panels of the buoyancy flaps 11, extended from the starboard side of the center section, and the extended buoyancy flaps 12 of the propulsion units.

To the magnetic docking buffers 7 is shown attached an optional, pressure-resisting crew module 14, while at the rear end, attached to similar docking buffers 7, is shown an optional self-contained long-range propulsion module 15.

Underneath, slung between its undercarriage legs can be seen the optional load 13, for example a 'U-Plane'.

Fig. 3 shows the location of the internal buoyancy bags 16 within the center section 1, and a number of presssureresisting enclosures 17, enclosed in the dorsal fin 9, for the supply of gas for the buoyancy system of the craft.

Sections of the rigid flaps 11 of the center section 1, and jalousy-type flaps 12 of the permanently attached propulsion units 4 are shown extended on the starboard side of the craft and retracted on the port side. The interior space 18 within the outer lightweight shell of the propulsion unit 4 is normally completely filled with pressure-resisting motors and their power supply.

In Fig. 4 is shown a front view of a different design option for the center section. In this embodiment, the lightweight center section 19 extends across the full width of the craft, with the propulsion units 4 attached directly to its sides. In this embodiment its interior is divided into gastight compartments or cells, preferably in the form of a honeycomb structure 20, shown in plan view at x 10 main drawing scale, which replaces the inflatable bags utilized and described in the previous embodiment.

Each cell is provided with valved means at its top, and is connected to the gas store individually; or else, preferably each transverse row of cells of the honeycomb structure from the dorsal fin in the middle of the center section outwards to port and to starboard is connected through a manifold system in such a way that each row of cells can thus be inflated with gas or deflated by means of a common valve.

When the valve at the top is closed, each cell behaves individually as a diving bell with straight and perpendicular side walls, and the whole row, as indeed the whole center section of the craft, behaves as a multitude of diving bells all acting together. Also, as in conventional diving bells, no pressure difference exists across the walls. For this reason and also due to the inherent strength of any honeycomb structure, this design contributes little weight.

In order to maintain a constant buoyancy contribution by any gas-filled cell or row of cells, the gas volume has to remain constant, and this is obtained by means of inflation or deflation under automatic or manual control from the gas store or gas generator.

However, in order to prevent constant hunting i.e. cycling of the gas system trying to adjust the gas pressure and hence volume of any of the inflated cells to an ambient pressure which is only varying slightly, for instance when the craft adopts an angle of inclination in the water, or when small fluctuation of depth occur repeatedly while essentially on a level cruise, it is advisable to provide valved means also at the bottom of each cell, or row of cells connected to a common manifold, and normally include this feature in a preferred design.

By means of springloading of the valves, or computer control, a small pressure difference can then be permitted to develop across the walls of the cells, i.e. the gas pressure within the cells can be maintained constant while the ambient pressure fluctuates,- within the design limits of the system.

Since the unloaded weight of the lifting module is comparatively light, only a few rows of honeycomb cells, preferably at or near the middle of the center section, need to be inflated with gas in order to provide neutral buoyancy when the craft enters the water from the shore, and hence all the remaining cells can stay deflated, with the valves both at their top and bottom open to permit water to pass freely.

Also all buoyancy flaps remain closed.

When a suitable load is to be lifted, the full production of positive buoyancy can be utilized by inflation of the whole of the interior of the center section, plus extension of the buoyancy flaps each offside of both propulsion units, plus use of all available power applied to the water jets for dynamic vertical thrust. Even more lifting power can be produced by coupling any number of lifting modules together by means of the docking system at both ends of each module.

The modules may be coupled together directly, in line, or they may be connected by means of a coupling adaptor. The coupling adaptor may connect two or more modules in parallel or at specified angles. Also, the adaptor may allow coupling between modules having different coupling configuration, and coupling systems.

In Fig. 5 is shown a Self-Contained Attachable Buoyancy Unit consisting of an inflatable elastic or flexible bag or balloon 21 normally folded in its deflated state in its compartment 22, in which it is attached by means of a cable connected to a winch system 23 which itself forms part of the assembly. This also includes a gas supply or gas generator 24 connected to the bag/balloon, and a power supply 25 for gas generation, operation of the winch, and provision of power for the control and operation systems.

It is shown attached to the non-buoyant load 26.

When required for lifting, the bag or balloon is partially inflated and, with the winch brake released, is permitted to rise out of its container and climb towards the water surface while meanwhile expanding and thereby increasing its water displacement and hence also its positive buoyancy.

When this has reached a sufficient value, the winch brake is applied, or else when the cable has fully unwound, the positive buoyancy of the unit will pull the load upwards towards the surface. Additionally, power can be applied to the winch to rewind the cable whereby the unit will in fact wind itself up to the surface with its attached load.

A major function for the SCAB Unit is its use as an autonomous, but fully self-contained attachment to a crew module, as an emergency system for rescue after the module has been detached from the docking buffers of a disabled Trans-Buoyant Submarine Craft, or, for instance, by means of explosive bolts, from the remainder of a disabled 'U-Plane'. Several SCAB Units can be provided on either side of the crew module or craft to allow it to be recovered from a tipped position.

Claims

Claims

1. A submersible craft comprising a hull member containing a plurality of inflatable buoyancy members, inflation means for inflating said buoyancy members, and control means for controlling said inflation means, wherein, when said craft is submersed, water enters the hull to fill at least some of the spaces between or in said buoyancy members.

2. A submersible craft according to Claim 1, wherein said control means is operable to control the inflation pressure within said buoyancy members in response to the ambient hydrostatic pressure, thereby to limit the differential pressure acting on the walls of the buoyancy member.

3. A submersible craft according to Claim 1 or Claim 2, wherein the dry mass of the craft is substantially less than the mass of the maximum displacement volume of the craft when submerged.

4. A submersible craft according to Claim 3, wherein the ratio of the dry mass of the craft to the mass of the maximum displacement volume is less than 1:3, whereby said submersible craft is capable of providing a considerable lift force.

5. A submersible craft according to any preceding claim wherein said plurality of buoyancy members comprises a regular array of inflatable cylindrical bags.

6. A submersible craft according to any of claims 1 to 4 wherein said hull includes an array of buoyancy cells open adjacent their lower ends, which may be inflated by the introduction of gas to define buoyancy members.

7. A submersible craft according to any preceding claim, wherein said hull member includes releasable engagement means whereby the craft may be connected to other craft in modular fashion.

8. A submersible craft according to any preceding claims, wherein said releasable engagement means comprises a magnetic or electro-magnetic coupling.

9. A submersible craft according to Claim 7 or Claim 8 which includes an acquisition control system for guiding relative engagement movement of said craft with another craft, and remote control, with feeback, of its operational functions and systems.

10. A submersible craft according to any preceding claims, including buoyancy boost means for providing additional buoyancy, said buoyancy boost means comprising a flap or bag deployable adjacent the outer surface of the hull for receiving gas from a gas source.

11. A submersible craft according to Claim 10, wherein said buoyancy boost means comprises a row of doors provided along each side of the hull member, each openable in gull-wing fashion to contain a volume of gas.

12. A submersible craft according to any preceding claim, wherein said craft includes twin outriggers spaced one from each side of the hull.

13. A submersible craft acording to Claim 12 wherein each of said outriggers includes outrigger buoyancy means comprising a bag or flap or other flexible or nonflexible container deployable to receive a volume of gas.

14. A submersible craft according to Claim 12 or 13, wherein each of said outrigger units comprises a propulsion unit.

15. A submersible craft according to Claim 14, wherein each propulsion unit includes means for vectoring the thrust generated thereby.

16. A submersible craft acccording to any preceding claim, which includes a downwardly extending frame assembly for supporting the craft off the ground or sea floor, and incorporating means for movement on the ground or sea floor.

17. A submersible craft according to Claim 16, wherein said frame assembly may be stowed in compact form.

18. A submersible craft according to any preceding claim, which includes means for picking up and retrieving an object below said craft.

19. A submersible lifting device, for example for recovering objects from the sea floor, comprising a base having means for attachment to an object to be lifted, a buoyancy bag connected to said base by a line, means for paying out or winching in said line, and means for introducing a volume of fluid into said buoyancy bag partially to inflate said bag to impart in use an upward thrust to said bag.

20. A submersible lifting device according to Claim 18, wherein said buoyancy bag includes pressure relief means.

21. A method of recovering an object from a depth of water, which comprises attaching said object to the base of a lifting device according to Claim 18 or 19, partially inflating said buoyancy bag, paying out said line to allow said buoyancy bag to ascend relative to said base, whereby the hydrostatic pressure acting on said bag decreases with a consequent further expansion of said bag and an increase in the buoyancy force experienced by said bag, until said buoyancy force is enough to lift said object, and, thereafter winching in said line to lift said object.

22. A submersible structure comprising a submersible craft according to any of Claims 1 to 18 assembled with at least one further module such as for example, one or more of a crew module, a propulsion module, or a lifting module.

23. A submersible structure according to Claim 22, wherein at least a part of at least one of said modules is formed of a composite material comprising a matrix of concrete, plastic or similar material containing a plurality of relatively lightweight and airtight capsules.

24. A submersible craft comprising a hull and buoyancy boost means deployable externally adjacent said hull for receiving a volume of gas to impart a buoyancy thrust.

25. A submersible craft according to Claim 24, wherein said buoyancy boost means comprises at least one door or bag in the hull section for opening in gull wing fashion to receive a volume of gas.

26. A submersible structure comprising a plurality of interconnected modules each including complementary engagement means.

27. A submersible structure according to Claim 26, wherein a coupling adaptor such as a connecting structure or bridge is provided for interconnecting adjacent modules, e.g.

in parallel arrangement, of the same or different coupling methods.

28. A submersible structure according to Claim 26 or 27, wherein one or more of said modules includes acquisition and guidance means for guiding the module into engagement with another, and means for remote control, with feedback, of its operational functions and systems.

29. A submersible structure according to the preceding claims wherein each separate module in addition to its main specialized function is also equipped with means for movement on the ground or sea floor, at least short-range movement in the sea to permit positioning for its interconnection with other modules under remote or preset control, and self-contained buoyancy means for itself and its load.

30. A composite material comprising a matrix of concrete, plastic or similar material containing a plurality of relatively light weight and airtight capsules, e.g. of glass.

31. A submersible craft comprising a hull member containing a close-packed array of buoyancy cells, means for supplying gas to said cells and control means for controlling said gas supply means.

32. A submersible craft according to Claim 30, wherein said cells are generally parallel to one another.

3:. A submersible craft according to Claim 30 or 31, wherein the cells are generally of polygonal, e.g.

triangular or hexagonal shape.

34. A submersible craft according to any of Claims 30 to 32, wherein valve means are provided for controlling flow into and out of the top and bottom of the cells.

35. A submersible craft according to Claim 33, wherein said cells are arranged in groups with a common upper valve means provided for controlling flow into and out of the tops of the cells of a group and a common lower valve means provided for controlling flow into and out of the bottom of the cells of the group.

36. A submersible craft according to Claim 34, wherein said groups of cells are inflated stepwise.

37. A submersible craft, substantially as hereinbefore described with reference to, and as illustrated in, any of the accompanying drawings.

38- A submersible structure, substantially. as hereinbefore described with reference to, and as illustrated in, any of the accompanying drawings.

39. A submersible lifting device, substantially as hereinbefore described with reference to, and as illustrated in any of the accompanying drawings.

45. A material, substantially as hereinbefore described with reference to, and as illustrated in, any of the accompanying drawings.

41. A method of recovering an object substantially as hereinbefore described with reference to the accompanying drawings.

Amendments to the claims have been filed as follows

1. A submersible craft comprising a hull member containing a plurality of inflatable buoyancy members, inflation means for inflating said buoyancy members, and control means for controlling said inflation means, wherein, when said craft is submersed, water enters the hull to fill at least some of the spaces between or in said buoyancy members.

2. A submersible craft according to Claim 1, wherein said control means is operable to control the inflation pressure within said buoyancy members in response to the ambient hydrostatic pressure, thereby to limit the differential pressure acting on the walls of the buoyancy member.

3. A submersible craft according to Claim 1 or Claim 2, wherein the dry mass of the craft is substantially less than the mass of the maximum displacement volume of the craft when submerged.

4. A submersible craft according to Claim 3, wherein the ratio of the dry mass of the craft to the mass of the maximum displacement volume is less than 1:3, whereby said submersible craft is capable of providing a considerable lift force.

5. A submersible craft according to any preceding claim wherein said plurality of buoyancy members comprises a regular array of inflatable cylindrical bags.

6. A submersible craft according to any of claims 1 to 4 wherein said hull includes an array of buoyancy cells open adjacent their lower ends, which may be inflated by the introduction of gas to define buoyancy members.

7. A submersible craft according to any preceding claim, wherein said hull member includes releasable engagement means whereby the craft may be connected to other craft in modular fashion.

8. A submersible craft according to any preceding claims, wherein said releasable engagement means comprises a magnetic or electro-magnetic coupling.

9. A submersible craft according to Claim 7 or Claim 8 which includes an acquisition control system for guiding relative engagement movement of said craft with another craft, and remote control, with feeback, of its operational functions and systems.

10. A submersible craft according to any preceding claims, including buoyancy boost means for providing additional buoyancy, said buoyancy boost means comprising a flap or bag deployable adjacent the outer surface of the hull for receiving gas from a gas source.

11. A submersible craft according to Claim 10, wherein said buoyancy boost means comprises a row of doors provided along each side of the hull member, each openable in gull-wing fashion to contain a volume of gas.

12. A submersible craft according to any preceding claim, wherein said craft includes twin outriggers spaced one from each side of the hull.

13. A submersible craft acording to Claim 12 wherein each of said outriggers includes outrigger buoyancy means comprising a bag or flap or other flexible or nonflexible container deployable to receive a volume of gas.

14. A submersible craft according to Claim 12 or 13, wherein each of said outrigger units comprises a propulsion unit.

15. A submersible craft according to Claim 14, wherein each propulsion unit includes means for vectoring the thrust generated thereby.

16. A submersible craft acccording to any preceding claim, which includes a downwardly extending frame assembly for supporting the craft off the ground or sea floor, and incorporating means for movement on the ground or sea floor.

17. A submersible craft according to Claim 16, wherein said frame assembly may be stowed in compact form.

18. A submersible craft according to any preceding claim, which includes means for picking up and retrieving an object below said craft.

19. A submersible lifting device, for example for recovering objects from the sea floor, comprising a base having means for attachment to an object to be lifted, a buoyancy bag connected to said base by a line, means for paying out or winching in said line, and means for introducing a volume of fluid into said buoyancy bag partially to inflate said bag to impart in use an upward thrust to said bag.

20. A submersible lifting device according to Claim 18, wherein said buoyancy bag includes pressure relief means.

21. A method of recovering an object from a depth of water, which comprises attaching said object to the base of a lifting device according to Claim 18 or 19, partially inflating said buoyancy bag, paying out said line to allow said buoyancy bag to ascend relative to said base, whereby the hydrostatic pressure acting on said bag decreases with a consequent further expansion of said bag and an increase in the buoyancy force experienced by said bag, until said buoyancy force is enough to lift said object, and, thereafter winching in said line to lift said object.

22. A submersible structure comprising a submersible craft according to any of Claims 1 to 18 assembled with at least one further module such as for example, one or more of a crew module, a propulsion module, or a lifting module.

23. A submersible structure according to Claim 22, wherein at least a part of at least one of said modules is formed of a composite material comprising a matrix of concrete, plastic or similar material containing a plurality of relatively lightweight and airtight capsules.

24. A submersible craft comprising a hull and buoyancy boost means deployable externally adjacent said hull for receiving a volume of gas to impart a buoyancy thrust.

25. A submersible craft according to Claim 24, wherein said buoyancy boost means comprises at least one door or bag in the hull section for opening in gull wing fashion to receive a volume of gas.

26. A submersible structure comprising a plurality of interconnected modules each including complementary engagement means.

27. A submersible structure according to Claim 26, wherein a coupling adaptor such as a connecting structure or bridge is provided for interconnecting adjacent modules, e.g.

in parallel arrangement, of the same or different coupling methods.

28. A submersible structure according to Claim 26 or 27, wherein one or more of said modules includes acquisition and guidance means for guiding the module into engagement with another, and means for remote control, with feedback, of its operational functions and systems.

29. A submersible structure according to the preceding claims wherein each separate module in addition to its main specialized function is also equipped with means for movement on the ground or sea floor, at least short-range movement in the sea to permit positioning for its interconnection with other modules under remote or preset control, and self-contained buoyancy means for itself and its load.

30. A composite material comprising a matrix of concrete, plastic or similar material containing a plurality of relatively light weight and airtight capsules, e.g. of glass.

31. A submersible craft comprising a hull member containing a close-packed array of buoyancy cells, means for supplying gas to said cells and control means for controlling said gas supply means.

32. A submersible craft according to Claim 31, wherein said cells are generally parallel to one another.

33. A submersible craft according to Claim 31 or 32, wherein the cells are generally of polygonal, e.g.

triangular or hexagonal shape.

34. A submersible craft according to any of Claims 31 to 33, wherein valve means -are provided for controlling flow into and out of the top and bottom of the cells.

35. A submersible craft according to Claim 34, wherein said cells are arranged in groups with a common upper valve means provided for controlling flow into and out of the tops of the cells of a group and a common lower valve means provided for controlling flow into and out of the bottom of the cells of the group.

36. A submersible craft according to Claim 35, wherein said groups of cells are inflated stepwise.

37. A submersible craft, substantially as hereinbefore described with reference to, and as illustrated in, any of the accompanying drawings.

38. A submersible structure, substantially as hereinbefore described with reference to, and as illustrated in, any of the accompanying drawings.

39. A submersible lifting device, substantially as hereinbefore described with reference to, and as illustrated in, any of the accompanying drawings.

40. A material, substantially as hereinbefore described with reference to, and as illustrated in, any of the accompanying drawings.

41. A method of recovering an object substantially as hereinbefore described with reference to the accompanying drawings.