WO2014037835A2

WO2014037835A2 - Hovercraft

Info

Publication number: WO2014037835A2
Application number: PCT/IB2013/056736
Authority: WO
Inventors: Marco MASTRANGELI
Original assignee: Hovertech Ltd
Priority date: 2012-09-06
Filing date: 2013-08-19
Publication date: 2014-03-13
Also published as: ITGE20120090A1; WO2014037835A3

Abstract

A hovercraft comprising a hull, whose lower part is laterally surrounded by an air duct for supplying air to form an air cushion, the duct being externally covered by air channeling members, known as skirts, and the hull supporting a propulsion system in its upper part, an air-flow generating system being also mounted to the hull. The hull further comprises a first upper part made of metal or a similarly rigid material, which is connected to a second lower part made of a plastic material, to create at least one zone between the first and second parts, for circulation of the air- cushion generating flow. The second part comprises a flexible plastic skin, which is placed at the bottom of the second lower part, at least one layer of a plastic material, in foam form, being interposed between the flexible plastic skin and the rigid frame.

Description

HOVERCRAFT The present invention relates to a hovercraft comprising a hull, the lower part of such hull being laterally surrounded by an air duct for supplying air to form an air cushion which entirely covers the lower part and acts as an underbody in contact with the ground and/or water surface.

The duct is externally covered by air channeling members, known as skirts, and the hull supports a propulsion system in its upper part.

An air cushion generating system is also mounted to said hull, and the leaking air acts as a lubrication film that greatly reduces friction with the underlying surface.

Hovercrafts are known as air cushion- supported vehicles, driven by one or more propellers of the propulsion system. The peculiarity of these vehicles is their ability to move on various types of surfaces, as they can navigate over water and travel on grounds, by being supported on their air cushion.

Hovercrafts may be currently used for multiple activities but, regardless of their use, these vehicles often operate in extreme conditions, considering the various types of surfaces over which they travel .

One of the main restrictions of these vehicles concerns the hull, which is susceptible to easy wear and damage, as it contacts bumps on the ground possibly at high speed, and may find obstacles whose height is greater than the thickness of the air cushion, which will impact on the rigid lower hull.

Particularly when the hovercraft runs on a solid surface, the latter is rarely even and smooth, and may have rocks, pebbles, stones, etc.

Such contact causes damage and/or wear to the hull and skirts of the hovercraft, but hull damage is more serious, as skirts are easily removable, at low cost .

However, the hull is currently made of expensive and sturdy materials, such as evlar and carbon fiber, and the use of the hovercraft inevitably causes constant wear, requiring servicing or replacement of the bottom of the hull, which involves high material costs and long servicing times, as the hull has a complex construction to allow skirt fixation and ensure a flow of pressurized fluid to form the air cushion.

Therefore, there exists a yet unfulfilled need for a hovercraft that can obviate the drawbacks of prior art vehicles, and particularly can preserve the hull or provide a easily replaceable and inexpensive hull, having low costs and an easy construction, as it can be mounted to the existing hovercraft structure.

The present invention achieves the above purposes by providing a hovercraft as described hereinbefore, wherein the hull is composed of a first upper part made of a metal material or a similarly rigid material, said first upper part being connected to a second lower part made of a plastic material, the first upper part being connected to the second lower part in such a manner as to create at least one zone between the first and second parts, for circulation of the air-cushion generating flow.

Furthermore, the second part comprises a flexible plastic skin which is located at the bottom of the second lower part, and has lateral air flow outlet holes.

Furthermore, at least one layer of a plastic material, in foam form, is interposed between the flexible plastic skin and the rigid frame.

It should be noted that the first upper part may be made of any high-rigidity material, typically a metal material such as carbon fiber or the like.

The use of a plastic skin provides a bottom layer of the hull that contacts the bumps on the ground and is softer than the materials that are used in prior art vehicles.

Also, since the skin is an independent part of the hull, it will be easily replaced in case of damage, with no excessive economic burden, as plastic materials generally have low costs and are easily processed.

Furthermore, the particular configuration of the hull affords mechanical strength as well as flexibility under stresses exerted by mechanical bodies .

This will provide a flexible system, i.e. a hull structure that is not subject to deformation or failure under the external forces of agents and unexpected impacts and that can be manufactured in an easy and repeatable manner.

The plastic foam material has various purposes : first it increases the elasticity of the whole hull, assists buoyancy of the hovercraft in the displacement mode and ensures adequate buoyancy of the vehicle even in case of tear of the plastic skin.

Furthermore, a closed-cell foam plastic material can ensure a good overall stiffness of the second lower part of the hull, in combination with high local elasticity properties in shock absorption during impact with various contact surfaces .

According to a preferred variant embodiment, the first upper part is connected to the second lower part via flexible coupling means, such as flexible joints or the like.

This will provide a hull that is basically composed of a first rigid upper part and a second elastic lower part, which are joined together by belt and strap arrangements, and are only flexible inwards, and not able to deform outwards under the air-cushion generating pressure and/or gravity, like the arrangements for connection of runners to the platform in polar sledges.

This arrangement provides a sandwich structure, which is characterized by both high strength, for bearing the weight of the superstructure, i.e. the propulsion means and instruments for users, as well as the weight of the users themselves, and good elasticity for absorption of shocks caused by ground impacts .

Impact absorption is further ensured by flexible couplings that connect the first part and the second part, such high absorption also having effects on safety, as it prevents impact transfer to the hovercraft crew and the structures overlying the first upper part. Furthermore, this particular type of structure provides various advantages during hovecraft maneuvers. When parking the hovercraft, the second lower part is better adaptable to the contact surface, without the risk that the hull material may be torn. Furthermore, more often than during parking, impacts and damages occur during high-speed travel, i.e. the on-cushion state, if an obstacle higher than the air chamber formed by the skirts intervenes, and impacts the hull at high speed. Ά sharp obstacle may be also located directly below water surface whereby when the hovercraft deactivates cushion formation, it will sink in the liquid, compatibly with buoyancy in fluids having different densities (700 ÷ 1000 kg/m³) and the obstacle may lift a part of the hull and even pierce it, if it has a sharp profile. Furthermore, in the displacement mode, such hull is inherently unsinkable, as the elastic and flexible hull is not designed to provide the buoyancy thrust, which is totally provided by the foam.

In one improvement, the plastic foam layer has specially shaped contact zones at its top, at the contact area between the first upper part and the second lower part, said contact zones extending over at least part of the upper surface of the plastic foam material .

Preferably, in order to prevent failure of the plastic foam material, the specially shaped contact zones consist of reinforcement members, adapted to bear the weight of the first upper part, the reinforcement members being made of a plastic material . Advantageously, the reinforcement members extend over the entire upper surface of the plastic foam material, for even distribution of the weight of the upper structure over such surface.

Alternatively, these reinforcement members may consist of a polygonal plastic frame, which is in turn composed of a plurality of elongate plastic elements that are joined together to define areas delimited thereby, for a plastic foam material to be introduced into such areas .

According to this configuration, the polygonal plastic frame is connected to the first upper part, whereas the flexible plastic skin is placed at the bottom of the second lower part.

Irrespective of the selected configuration of the reinforcement members, the main purpose of the plastic foam material is to act as an elastic element, i.e. a sort of spring, in much the same manner as springs in known mattresses.

According to a further improvement, the first upper part has a peripheral rim, extending along at least part of its length, which is made of a flexible plastic material, preferably the same material as the skin.

The peripheral rim joins to the skin in partial or total overlapping relationship thereto.

The connecting portion between the skin and the peripheral rim may be formed in any manner, with the two layers fixed together e.g. by fastener means or by sealing or bonding.

Such peripheral rim has a further shock absorption purpose, as it protects the hull at its sides in case of impact and does not damage the parts of the hull as it is fixed to flexible structures.

Preferably, the skin and the plastic foam material are joined together by fastening means such as belts or the like, said skin having housings formed therein for fixation of the fastening means .

As illustrated in detail through certain exemplary embodiments, loops may be provided on the top face of the skin, for housing belts or straps that are designed to fasten together the parts that compose the second lower part of the hull, thereby creating a sandwich structure comprising the plastic skin, a first layer of plastic foam material and any reinforcement member.

This will provide a compact system that features all the above described mechanical properties, in which the more rigid part does not directly contact the plastic skin, but lies on the first layer of plastic foam material, thereby avoiding the presence of rigid points directly in contact with the plastic skin, which will create breaking points when sliding over bumps .

In one embodiment, the plastic skin of the hovercraft of the invention is composed of two hot- bonded layers of plastic material, a net of synthetic and/or natural and/or metal fibrous material being interposed between the layers .

This arrangement imparts improved mechanical properties to the hull and for this purpose the skin may be designed to have increasing densities from the bottom face of the hull .

Advantageously, the first upper part consists of a polygonal metal frame, composed of a plurality of mutually joined elongate metal members. The polygonal metal frame is connected to the second lower part to create at least two zones which are delimited at the top by the first upper part and at the bottom by the second lower part, for circulation of the air-cushion generating flow, such two zones communicating with the holes formed in the plastic skin.

As a result, the rigid structure of the first upper part is connected to the more rigid structure of the second lower part, to prevent damages to softer structures, such as the plastic foam material, and to increase the rigidity of the system without affecting the elasticity of the second lower part of the hull.

Preferably, the polygonal metal frame is composed of at least two elongate metal members, which are oriented parallel to the bow- stern axis of the hovercraft, and are joined together via two or more transverse elongate members oriented perpendicular to the bow- stern axis, said transverse elongate members having an extension perpendicular to the bow-stern axis.

At least two diagonal elongate members are arranged each with its ends alternatively connected to the at least two main elongate metal members.

Finally, a peripheral edge is provided, for surrounding and enclosing the elongate metal members that form the polygonal metal frame.

The structure of the polygonal metal frame will be further elucidated by the following description of a few exemplary embodiments, such structure being always adapted to optimize the compromise between weight and rigidity of the hull and air channeling, and being characterized by an adequate torsion strength, for improved ocean wave strength.

Studies have been also conducted to select the best material for each part of the hull, in view of optimizing the above described mechanical properties.

Thus, the polygonal metal frame is made of an aluminum alloy, particularly Anticorodal 606o (or Peraluman 5083) , whose technical features are available and known in the art.

The skin and reinforcement members are made of high-density polyethylene of the PE-H U type or the like.

On the other hand the plastic foam material is made of a low-density polyethylene foam of the PLASTAZOTE^® type or the like, i.e. a material having a high local deformability and a high overall stiffness .

In a particular embodiment, a platform is attached to the polygonal metal frame for supporting the propulsion system and the air-cushion generating system, as well as any control and operating means and equipment of the hovercraft.

Advantageously, the platform covers the entire length of the hull and is perfectly flat.

The platform so formed acts as a "working platform" upon which all the equipment of the hovercraft is arranged and the crew operates.

A flat shape of the platform will prevent a "bath tub effect", i.e. the creation of a potentially floodable closed space, that may be easily flooded by breaking waves or waves of considerable amplitude, thereby increasing weight beyond load specification and preventing high-speed "on-cushion" travel. Particularly, the hovercraft of the present invention comprises at least one control unit, one or more seat elements, one or more rail elements, one or more housing elements acting as storage spaces, as well as the above-mentioned propulsion system and air-cushion generating system.

These parts may be provided instead of or in combination with one another and instead of or in combination with typical prior art hovercraft parts .

The control unit may consist of a manual control unit as is known in the art or a remote control unit, such that an operator may remotely control hovecraft movements .

One of the main advantages of the hovercraft of the present invention is its modularity, which means that it appears as a vehicle having a hull part, allowing various modular units and/or bodies to be removably mounted thereon.

Particularly, the control unit and/or the seat elements and/or the rail elements and/or the housing elements acting as storage spaces and/or the propulsion system and/or the air-cushion generating system are separate modular units that are removably mounted to the platform.

Preferably, the latter from is formed as a grid, allowing the modular units to be fixed thereto in any position of the platform, otherwise it has couplings structurally connected to the underlying frame.

Thus, the hovercraft of the present invention is a finished product consisting of a hull part that may have any type of body mounted thereto to carry out a variety of activities. This aspect also affords economic advantages as the hull parts is adaptable to various market demands, which decreases manufacturing costs.

Furthermore, the possibility of displacing the parts of the hovercraft to various positions enhances the operativity of the vehicle in terms of weight distribution over the platform.

The basic aspect for hovercraft operation is proper weight distribution, which is often a difficult and/or laborious task, and this problem is solved by the provision of a platform in the form of a uniform mesh grid, or systems for fixation to the structural frame, that afford various positioning arrangements, and facilitate the displacement of modular units both according to their weight and according to the number of people on the hovercraft.

According to a particular embodiment, the propulsion system comprises drive means for driving at least one propeller and the air-cushion generating system consists of air- flow generating means which convey the air flow into the channeling elements .

Here, both systems are integrated in a single modular propulsion unit.

Advantageously, this modular propulsion unit has at least one outlet for conveying the air flow into the channeling element, which communicates therewith via a corresponding aperture formed in the platform, preferably in the rear portion of such platform.

The longitudinal position and attitude of the modular propulsion unit on the platform may be also adjusted because the aperture on the platform for communication with the flow channeling outlet has an elastic sealing lip, which automatically fits the size and position of the outlet by the pressure generated for forming the air cushion, which further ensures watertightness .

This feature extends one of the main advantages of the hovercraft of the present invention, i.e. modularity, to the propulsion and air-cushion generating system.

This will afford the creation of systems composed of multiple hovercrafts, such as larger working platforms formed by joining together the lower hull parts of a plurality of hovercrafts formed as described above and propelled by multiple modular propulsion and lift systems.

This combination of hulls is facilitated by the perfectly flat shape of the working platforms of the hovercrafts.

More generally, the above modularity allows the provision of larger hovercrafts manufactured with the same technique and propelled by two or more modular propulsion units.

The present invention also relates to a hull from marine vessels, such as boats, hovercrafts or the like, which comprises a first upper part made of metal material, such first upper part being connected to the second low were part made of a plastic material .

Particularly, the hull of the present invention is constructed according to one or more of the above described features concerning the hull of the hovercraft of the present invention.

The present invention also relates to a hovercraft comprising a hull whose lower part is laterally surrounded by an air duct for supplying air to form an air cushion, the air-cushion entirely- surrounding the lower part and acting as an underbody in contact with the ground and/or water surface, the duct being externally covered by air channeling members, known as skirts, and the hull supporting a propulsion system in its upper part, an air- flow generating system being mounted to the hull for forming such air-cushion.

The hovercraft further comprises the platform located above the hull and having a perfectly flat shape .

Particularly, the hovercraft is constructed according to one or more of the above described features.

These and other features and advantages of the invention will be more apparent from the following description of a few embodiments shown in the accompanying drawings, in which:

Fig. 1 shows a prior art hovercraft;

Figs . 2a and 2b show two front views of the hull that is part of the hovercraft of the present invention;

Figs. 2c to 2f show different views of the hull that is part of the hovercraft of the present invention;

Figs. 3a to 3m show different details of the second lower part of the hull that is part of the hovercraft of the present invention;

Figs. 4a to 4d show different details of the first upper part of the hull that is part of the hovercraft of the present invention;

Figs. 5a and 5b show the platform of the hovercraft of the present invention; Figs . 6a to 6c show three views of the hovercraft of the present invention, according to a possible embodiment;

Fig. 7 shows the propulsion system and the air- cushion generating system of the hovercraft of the present invention;

Figs. 8 to 10 particularly show various embodiment of the platform of the hovercraft of the present invention;

Figs. 11 and 12 show two different embodiments of the hovercraft of the present invention;

Figure 1 shows a prior art hovercraft.

The hovercraft comprises a hull laterally surrounded by an air duct 31 for supplying air to form the air cushion, the duct 31 being externally covered by air channeling members, known as skirts 3.

Typically, hovercrafts have a propulsion system 4 composed of one or more propellers 41 driven by drive means and an air-cushion generating system 5, also generally composed of propellers 51 driven by drive means.

The first system is used to move the hovercraft whereas the second is used to lift the hovercraft, and the propellers 51 are generally ducted and supply part of the generated air to the skirts 3 through a duct 31.

The air generated by the propellers 51 and conveyed to the skirts 3 creates a constant outflow toward the surface, which allows the hovercraft to be supported by an air cushion.

The part of air that has not been conveyed is generally used as a thrust to move the hovercraft forward, steering being possibly obtained using rudders, not shown in figure 1.

Figures 2A and 4d shows the hull of the hovercraft of the present invention, in which the hull comprises a first upper part 1 made of a metal material or a similarly rigid material, which is connected to a second lower part 2 made of a plastic material .

The first upper part 1 is connected to the second lower part 2 in such a manner as to create at least one zone 121 between the first and second parts, for circulation of the air-cushion generating flow.

Particularly, Figures 2a and 2b show two front views of the hull, whereas Figures 3a to 3h and 4a to 4g show details of the second lower part 2 and the first upper part 1 respectively.

The second lower part 2 comprises a flexible plastic skin which is located at the bottom of the second lower part 2, and has lateral air flow outlet holes 231.

Furthermore, at least one layer of a plastic material, in foam form, is interposed between the flexible plastic skin 23 and the rigid frame.

Figures 2c and 2d show two views of the hull of the hovercraft of the present invention.

According to a preferred variant embodiment, as particularly shown in Figures 2e and 2f, the plastic foam layer 22 has specially shaped contact zones 221 at its top, at the contact area between the first upper part 1 and the second lower part 2, said contact zones 221 extending over at least part of the upper surface of the plastic foam material 22. Particularly, the specially shaped contact zones 221 consist of reinforcement members, adapted to bear the weight of the first upper part 1 and distribute such weight over the plastic foam material 22, the reinforcement members being made of a plastic or honeycomb sandwich material .

In a further improvement, the reinforcement members 221 extend over the entire upper surface of the plastic foam material 22.

Still particularly referring to Figures 2e and

2f, the first upper part 1 has a peripheral rim 232, extending at least along part of its length, which is made of a flexible plastic material, preferably of the same material as the skin 23, the peripheral rim joining to the skin 23 in partially or totally overlapping relationship.

According to a further embodiment, the reinforcement members 221 may consist of a polygonal plastic frame 21, which is in turn composed of a plurality of elongate plastic elements 211 that are joined together to define areas delimited thereby, for a plastic foam material 22 to be introduced into such areas.

Figure 3a particularly shows the assembly of the polygonal frame 21 and the plastic foam material 22, whereas Figure 3c shows the polygonal frame 21.

The polygonal frame 21 may be constructed in any manner.

Many arrangements of the elongate elements 211 are possible, as long as the polygonal frame 21 acts as a rigid structure for the second lower part 2 of the hull, for supporting the plastic foam material 22. Preferably, the elongate elements 211 are bonded together, although any kind of joint may be used to join one elongate element 211 to another.

As shown in Figure 2a and as described in the next figures, the second lower part 2 is connected to the first upper part 1.

The second lower part 2 also has a flexible plastic skin 23 which is located at the bottom of the second lower part 2, and has lateral air flow outlet holes 231.

Particularly, Figures 2b and 3b show that the plastic skin has a plurality of peripheral holes 231 which communicate with the duct 31 to convey the air flow therein.

Preferably, the first upper part 1 is connected to the second lower part 2 via coupling means, such as belts, straps, flexible joints or the like.

Preferably, the skin 23, the plastic foam material 22 are joined together by fastening means 6 such as belts, straps, flexible joints or the like, the skin 23 having housings formed therein for fixation of the fastening means 6.

Particularly, the second lower part 2 as described above is shown as a layered structure, namely a sandwich structure, in which the layers are held together by a belt 6 that is secured to the skin 23 through loops 61 formed on the top face of the skin 23, as shown in Figures 3f and 3h.

Figure 3c shows a weave of belts 6 obtained by joining belts oriented parallel, transverse and perpendicular to the bow-stern axis of the hovercraft . In a further improvement, as shown in Figures 31 and 3m, a system is provided for connecting the layers together using straps or belts or cables individually attached to tapes directly sealed to the bottom, with Figure 3m showing a detail of Figure 31.

According to a possible embodiment, the skin 23 is composed of two hot-bonded layers made of a plastic material, a net of synthetic and/or natural and/or metal fibrous material being interposed between the two layers made of a plastic material .

Figures 4a to 4d show a possible embodiment of the first upper part. It shall be noted that the purpose of this first upper part 1 is to impart stiffness to the whole structure of the hull, whereby any structure made of metal or a similarly rigid material may fulfill this purpose and falls within the scope of the present patent application.

Thus, while the figures show an exemplary embodiment of such first upper part 1, this example is only to be intended by way of illustration and without limitation to the general principle of the invention.

Particularly, the first upper part 1 consists of a polygonal metal frame 11, composed of a plurality of mutually joined elongate metal members .

The polygonal metal frame 11 is connected to the second lower part 2 to create at least two zones 121 which are delimited at the top by the first upper part 1 part and at the bottom by the second lower part, for circulation of the air-cushion generating flow, such two zones communicating with the holes 231 formed in the plastic skin 23. Particularly referring to Figures 4a to 4d, the polygonal metal frame 11 is composed of at least two main elongate metal members 111 oriented parallel to the bow-stern axis of the hovercraft. The two main elongate metal members 111 are joined together by two or more transverse elongate metal members 112 oriented perpendicular to the bow-stern axis, and having an extension perpendicular to the bow-stern axis beyond the main members 111, as shown.

Particularly, the transverse elements 112 may be formed of one piece, or divided into three parts, i.e. a first central part and two side parts located symmetrically with respect to the bow- stern axis.

Furthermore, in order to further increase stiffness, a peripheral edge 114 is provided, surrounding and enclosing the elongate metal members 111, 112 and 113 that form the polygonal metal frame 11.

The peripheral edge 114 may be formed of one piece or be composed of several elongate metal members, although it preferably has a shape conforming that of the outer peripheral edge of the hovercraft .

Depending on construction requirements, the elongate metal elements may have any profile whatever, i.e. they may be tubular elements, box-like elements or simple metal girders.

The elongate metal members 111, 112, 113 and 114 may be joined together by any coupling, and particularly Figures 4c and 4d respectively show two elongate metal members joined by bonding and using a perforated cleat formed by two sheet elements, such that each sheet element is fastened to the first and second elongate members respectively.

Figures 5a and 5b show a detail that us part of the hovercraft of the present invention, i.e. a platform 7 fixed to the polygonal metal frame 11.

This platform is adapted for support of the control means to be used by operators and all hovercraft equipment.

The platform 7 may be connected to the polygonal metal frame 11 using flexible coupling means, such as silent blocks 71 or the like.

Furthermore, the platform 7 covers the entire length of the hull and is preferably perfectly flat.

The platform 7 has a particularly important role in one of the main advantages of the hovercraft of the present invention, i.e. modularity.

As clearly shown in some of the exemplary embodiments hereinbelow, the platform 7 has such a shape as to be able to adapt to various possible parts of the hovercraft that are provided as modular units .

The platform 7 is formed as a grid or with couplings coinciding with structural parts of the underlying frame, thereby allowing the modular units to be fixed thereto in any position of the platform 7.

Particularly referring to Figures 6a to 8, the hovercraft of the present invention has a control unit 81, one or more seat elements 82, one or more rail elements 83, one or more housing elements acting as storage spaces 84, as well as the propulsion system 4 and the air-cushion generating system 5. Further different parts may be provided in addition to the above, which are known in the art and used in common hovercrafts for a variety of activities .

Irrespective of the number and type of parts, one, some or all of these parts may be provided as separate modular units, removably mounted to the platform 7.

Fastening points will be thus provided on the platform 7 in predetermined positions, for fixation of the modular units, which are provided with fastening means mating with the fastening points of the platform 7.

The fastening points of the platform 7 may be connected with the fastening means of the various operating units using any prior art device, such as screw-bolt couplings or flexible joints such as Silent Blocks, or by form fits of a first part to a mating second part or the like.

It should be noted that, according to a particular embodiment, in the hovercraft of the present invention, the propulsion system 4 comprises drive means for driving at least one propeller 41 and the air-cushion generating system 5 consists of air- flow generating means 51 which convey the air flow into the holes 231 formed in the skin 23.

The propulsion system 4 and the generating system 5 are integrated in a single propulsion unit, as shown in Figure 7.

Particularly, the modular propulsion unit has two outlets 52 for channeling the air flow into holes 231, said outlets being provided proximate to the propellers 51. The modular propulsion unit may be fixed to the platform 7, like all the other modular units, and particularly the two outlets 52 communicate with the holes 23 through two corresponding apertures 72 formed in the platform 7, which are preferably provided in the rear portion of the platform 7, and are designed for watertight engagement of the two outlets 52 once the modular propulsion unit is fixed to the platform 7.

Particularly, Figure 12 shows a variant embodiment in which two modular propulsion units are placed on a larger platform, in which case the hull dimensions may preferably be about 9 meters in length and about 4.4 meters in width, which allows mounting of two modular propulsion units.

The easy assembly of the parts of the hovercraft of the present invention and the simple construction of the platform 7 allow various configurations, and one example is shown in Figure 11, where four hovercrafts have been joined to form a larger platform, on which various operations may be carried out, as required by the user.

In the particular case of Figure 11, a drilling machine is installed on the platform obtained by joining the four hovercrafts.

It shall be finally noted that all the features as described herein concerning both the hull and the other parts of the hovercraft may be used on any water or ground vehicle.

Figure 13 illustrates the modularity concept of the hovercraft of the present invention, and shows the various possible solutions allowed by the use of a structure as described above. Particularly, the use of the hull as described and claimed herein, in combination with the platform 7 may provide various types of vehicles, according to the requirements of the final user, by simply changing the modular units mounted to the platform or changing the dimensions of the hull and platform.

In addition to the above described configurations, such as a hovercraft for civil protection and firefighting services 91, by changing, for example, the cabin size, a vehicle designed for use as an ambulance 92 may be turned into a vehicle designed for military and/or police use 93, or even a passenger vehicle 94.

The construction characteristics of the hull and platform of the hovercraft of the present invention will also allow the fabrication of vehicles as shown in the previous figures, namely in Figures 11 and 12, and also shown in Figure 13, referenced 95 and 96 respectively.

Claims

1. Hovercraft comprising a hull, the lower part of which is surrounded laterally by an air supply duct (31) required to produce a cushion of air which covers entirely the lower part of the hull that is in contact with the ground and/or the surface of the water, the said duct (31) is covered externally by components which channel the flow of air that is the so-called "skirts" (3) , the said upper part of the hull supports a propulsion system (4) and a system which generates (5) a flow of air for the formation of the air-cushion,

characterised in that

fthe hull consists of an upper part (1) made of a metallic type of material or material with similar rigidity. This upper part (1) is connected to a second (2) and lower part made of a plastic material, the upper part (1) is connected to the lower part (2) in such a way to create at least one zone between the two (121) where the flow of air can circulate, this zone is required for the creation of the cushion of air,

being the lower part (2) of the hull made of a plastic "skin" (23) that is flexible, This "skin" has lateral outlets to allow for the exit of the flow of air,

in between this plastic flexible "skin" (23) and the rigid frame there is at least a layer of plastic in the form of foam (22) .

2. Hovercraft according to claim 1, where the first upper part (1) is connected to the second lower part (2) via a joining system consisting of, for example belts, zip ties, flexible joints or similar.

3. Hovercraft according to one or more of the previous claims, in which the layer of plastic material in the form of foam (22) , takes the shape of the contact areas present in first upper part (1) and the second lower part (2) , the contact zones extend for at least part of the upper surface of the plastic material which is in the form of foam (22) .

4. Hovercraft according to one or more of the above previous claims, in which the areas in contact with the upper part of the foam are made up of reinforcements present to sustain and distribute the weight of the upper part (1) , these reinforcements are made of plastic material or alveolar sandwich or similar.

5. Hovercraft according to one or more of the previous claims, where the elements used for reinforcement extend across the entire surface of the plastic foam material (22) .

6. Hovercraft according to one or more of the above claims, in which the first upper part (1) has a peripheral frame, at least for part of its length, made of the same plastic flexible material referred to as "skin" (23) , this peripheral frame is joined to the "skin" (23) in such a way so as to be superimposed, partially or completely.

7. Hovercraft according to one or more of the previous claims, in which the plastic material in the form of a foam (22) and the "skin" (23) are joined together via fittings (6) of various types such as belts or similar, the "skin" (23) has special areas (61) where the fittings can fit in and be fixed.

8. Hovercraft according to one or more of the previous claims, in which the so-called "skin" (23) is made of 2 layers of plastic material joined together by heat, in between is a netting of fibrous synthetic and/or natural and/or metallic material.

9. Hovercraft according to one or more of the previous claims, in which the first upper part (1) consists of a polygonal metal frame (11) made up of a number of elongated unified metal elements,

this polygonal metal frame (11) is connected to the second lower part of the hull in such a way so as to create two boundary walls, one with the first upper part (1) the other with the second lower part (2) , inside this area air required to create the cushion of air circulates - this flow of air eventually passes through outlets present in the plastic "skin" (23) .

10. Hovercraft according to one or more of the previous claims, in which the aforementioned polygonal metal frame (11) is made up of at least two elongated main metal elements (111) parallel to the bow-stern axis of the said hovercraft, these two elongated main metal elements (111) are connected to each other via two or more transversal elongated elements (112) that are perpendicular to the bow- stern axis,

being also present a peripheral border (114) which surrounds and closes the elongated metal elements - this is the so-called polygonal metal frame (11) .

11. Hovercraft according to one or more of the preceeding claims in which the elements for reinforcement and the "skin" (23) are made of polyethylene of high density of the PE-HWU type or similar.

12. Hovercraft according to one or more of the previous claims, in which the afore-mentioned plastic material in the form of foam (22) consists of a polyethylene foam of low density of the PLASTAZOTE^® type or similar.

13. Hovercraft according to one or more of the previous claims, where a platform (7) is attached to the polygonal metal frame (11) its function being to support the propulsion system (4) and the system for the generation (5) of the air cushion as well as, eventually, of other command instruments and operators and equipment of the hovercraft,

the platform (7) being connected to the polygonal metal frame (11) via flexible joints such as, for example, silent blocks or similar,

this same platform (7) covers entirely the length of the hull and is foreseen to be perfectly flat.

14. Hovercraft according to one or more of the previous claims where a control unit is present and also one or more seats, one or more rails, one or more areas for the creation of storage spaces and the propulsion system (4) and the system for creating (5) the cushion of air.

15. Hovercraft according to one or more of the above claims in which the control unit and/or the seats and/or the rails and/or the areas for the creation of storage spaces and/or the propulsion system (4) and/or the system for the creation (5) of the cushion of air consist of modular units mounted separately in a way that they can be removed from the platform (7) .

16. Hovercraft according to one or more of the preceeding claims, where the platform (7) is in the form of a grid made of a uniform weave which guarantees that the single modular units can be mounted in whichever position of the said platform. (7) .

17. Hovercraft according to one or more of the above claims in which the propulsion system (4) includes the transmission system to drive at least one propeller (41) and the system for the generation (5) of the cushion of air. It consists of mechanisms for the generation (51) of the flow of air which is then routed into the so-called ducts,

being the propulsion system (4) and the system for the generation (5) of air are integrated inside one propulsion modular unit.

18. Hovercraft according tp one or more of the previous claims, where the modular propulsion unit foresees at least one outlet (52) required for routeing/channelling the flow of air inside the ducts via a corresponding aperture (72) which is present on the platform (7) , preferably in the posterior part of the platform (7) .

19. Hull for marine vessels, of the boat type, hovercraft or similar, characterised in that the hull is made up of an upper part (1) in metal connected to a second lower part in plastic material.

20. Hull for marine vessels of the boat type or similar according to claim 19, characterised in that it is realised according to one or more of the characteristics stated within the previous claims 1 to 13.

21. Hovercraft comprising a hull in which the lower part is surrounded laterally by an air feeding duct (31) the function of which is to create a cushion of air which surrounds entirely the lower part which is in contact with ground and/or water surface. This duct (31) is covered on the outside by the channelling elements called "skirts" (3) , the hull, in the upper part, supports a propulsion system. (4), being also present, mounted on the hull, the system for the generation (5) of a flow of air for the creation of the air cushion.

characterised in that a platform (7) is positioned above the hull and its role is to support the propulsion (4) system and the system for the generation (5) of the air cushion as well as controls and operators and equipment of the hovercraft. The platform (7) is perfectly flat.

22. Hovercraft in accordance with claim 21 is characterised by the fact that is has one or more of characteristics present in claims 1 to 20.