GB2128302A - An explosive or training apparatus for underwater use - Google Patents

Abstract

An underwater explosive or training apparatus which is simple to handle, so that a frogman can transport the apparatus with relatively slight effort and apply same to the target object that is to be blown up. For this a housing 4 is provided in which the working components of the apparatus are arranged symmetrically between two buoyancy chambers 5, 6, so that the centre of gravity of the apparatus 1 lies approximately in the geometric centre of the apparatus. The working components include fastening or clamping means 27, 28 enabling the apparatus to be fastened rapidly to the target object. The position of centre of gravity is also advantageous for the transportation by the frogman, since he is not burdened unevenly on one side. <IMAGE>

Description

SPECIFICATION An explosive or training apparatus for underwater use The invention relates to an explosive or training apparatus for underwater use of a kind comprising a housing provided with internal chambers of which a first chamber is adapted to contain a device, for example, an explosive device.

An apparatus comprising a housing for a hollow explosive charge for underwater use is known from German Patent No. 27 46 559. Two chambers are provided in the housing. A first chamber contains a hollow explosive charge, whilst a second chamber has an opening which is permeable to liquid. The chamber provided with the explosive charge is sealed with a sealing part through which a detonating loop of a detonating cord is conducted. Upon usage, the housing is loaded by suspending a weight and thus sinks until it stands on a rock bed. The water present in the second chamber is removed by way of compressed air, so that the hollow charge jet of the detonated explosive charge can develop freely in the space within the second chamber. This known apparatus is, for certain reasons, not suitable for use as an explosive or training apparatus for frogmen.The second chamber has to be flooded in the water and then to be blown out by means of compressed air when disposed on a target object to be destroyed, and use of this apparatus, requires a relatively great deal of time, hinders the swimmer because of its relatively great weight and requires the user to transport a cylinder of compressed air with the apparatus in order to blow the second chamber.

An object of the invention is to provide an explosive or training apparatus for underwater use which can be handled easily and rapidly by the frogman above and in the water and can be affixed reliably to the target object. The apparatus is preferably arranged so that the housing can be made pressure-stable in water to 50 metres depth.

According to the present invention there is provided explosive or training apparatus for underwater use comprising a housing, an explosive or acoustic device, and fastening or clamping means for attaching the apparatus to an object, characterised in that the housing comprises a median portion disposed between buoyant portions; in that said median portion provides a first chamber in which said explosive or acoustic device is located so that an external surface of the device is substantially co-planar with an external surface of the housing to provide a substantially flat abutment face for the apparatus and so that a centre line of said median portion passes through said device; in that said buoyant portions define second and third chambers and project beyond said median portion to provide accommodation of recess form between said buoyant portions, in which accommodation the fastening or clamping means is located alongside the median portion and in which accommodation at least part of means for actuating or controlling said device is located in operative connection with said device in said first chamber.

The flat abutment surface allows, in conjunction with the use of appropriate carrying straps, the frogman to transport the explosive or training apparatus on his back, and enables the apparatus to be secured by means of the fastening or clamping means so that the explosive acoustic device is in direct contact with the target object without any intervening space.

The positioning of the relatively dense parts of the apparatus, such as said device, the actuating means and the fastening or clamping means, in and around or close to the middle of the apparatus, enables the centre of gravity of the apparatus to be positioned at or adjacent to the geometrical centre, or a median plane containing the geometrical centre, of the apparatus; and the positioning of said dense parts between the buoyant or relatively much less dense portions of the apparatus enables the centre of buoyancy of the apparatus to be located at or adjacent to the centre of gravity, so that the apparatus is easy to manipulate to and hold in a desired position when underwater.

The invention more particularly provides explosive or training apparatus for underwater use, comprising a housing provided with internal chambers, of which a first chamber contains an explosive or acoustic device and a second chamber has means for admitting liquid, characterised in that the housing is of approximately U-shaped, thin-walled, metallic construction and has a flat and smooth abutment surface, the limbs of the U-shaped housing being of hollow form to provide the second chamber and a third chamber as buoyancy bodies; in that the explosive or acoustic device lies approximately centrically to a cross-sectional plane intermediate the limbs, so as to terminate flush with the abutment surface; in that a detonating or actuating device is disposed coaxially with the explosive or acoustic device at the rear of the first chamber of the housing; and in that fastening or clamping means, for securing the apparatus to a target object, is mounted on a shaft in a recess between the limbs.

Positioning the buoyant chambers in the limbs of the housing, and positioning the detonating or actuating device and the explosive or acoustic device between the limbs results in the apparatus having a centric centre of gravity. As previously mentioned this position of centre of gravity facilitates transportation in the water and brings about at the target object the fact that a relatively short length of the fastening or clamping means, such as link chain or supporting cable, is sufficient for fastening the apparatus to the target object. In particular, in use, the apparatus, provided with slight negative buoyancy in the water, is easily applied to and aligned with the object by the frogman so that an axis through the centre of gravity and the abutment face extends to or close to a central part or main axis of the target object.

The fastening or clamping means is then unwound, placed around the object and anchored to the apparatus. Only then is the fastening means tensioned to clamp the apparatus to the object. If an asymmetrical centre of gravity were present, the apparatus would be difficult to apply to the object without there being or arising a corresponding displacement or misalignment, which would require correction by use of the fastening or clamping means necessitating the provision of, unwinding of and tensioning of a greater length of the fastening or clamping means.

Therefore perforce more time would be needed for operation, particularly tensioning, of the fastening means, than is required in the present case wherein the apparatus has an approximately centric centre of gravity. Centralising the centre of buoyancy further reduces the risk of misalignment arising.

Arrangement of the detonating device and explosive charge on a common axis passing through the object guarantees a good energy transfer and thus effective damage to the object.

As a result of the two limbs acting as buoyancy chambers, the surface exposed to the water pressure is relatively small, so that in the case of aluminium casting a wall thickness of about 7 mm withstands the pressure in 50 metres depth of water. Also, as a result of the relatively thin-walled material, the overall weight of the apparatus can be kept to about 30 kg and is therefore easily transportable on land.

The housing is preferably provided with fastening facilities, arranged inside the contour, for belts, so that on all sides of the housing there are smooth surfaces to facilitate the manipulation of the housing.

The housing is preferably coated or covered with resilient material so that disturbing noises upon the application of the apparatus to the object are minimised by deadening by the material, e.g. a layer of plastics material such as polyurethane foam. Also, the elongate extensible portion, such as a cable or chain, of the fastening or clamping means is preferably coated with a layer of such a resilient sound deadening material.

The volume of the cavities are preferably determined so that the apparatus has a small positive buoyancy in fresh water, so that by flooding of a specific volume, a slight negative buoyancy can be imparted to the apparatus. The slight negative buoyancy makes possible the relatively simple movement of the body in the water. The means for admitting water preferably comprises a flooding tube, which, when not flooded, permits the apparatus to float. This is essential for delivery of the apparatus by parachute so that the apparatus floats to the surface and is thereby easy to find.

The risks of serious weight or buoyancy problems arising in the event of faulty operation, as is possible in the case of a large-volume chamber that has to be flooded or blown, are minimised by enabling a small volume flooding tube to be used in such apparatus. The flooding tube is in any case always fully flooded in order to achieve the slight negative buoyancy so that such risks are substantially obviated. The adaptation to the different buoyancy conditions in fresh water and salt water can be easily effected by additional weights which, by reason of the relatively small dimensions of the apparatus, are correspondingly small.

The aforesaid attributes and advantages of the explosive apparatus also apply to the training version of the apparatus. In the case of the training apparatus merely the detonating device and the explosive device are exchanged for an actuating device for triggering an acoustic device corresponding in weight and volume to the explosive device. The position of centre of gravity of the apparatus is thus maintained, so that the handling of the training apparatus corresponds to that of the explosive apparatus.

The invention will be described further, by way of example, with reference to the accompanying diagrammatic drawings, in which: FIGURE 1 shows an explosive or training apparatus of the invention as back load of a frogman; FIGURE 2 shows the explosive or training apparatus in accordance with Figure 1 in front elevation with its flat abutment surface foremost; and FIGURE 3 shows the explosive or training apparatus in side elevation on a target object.

An explosive or training apparatus 1 is provided with straps 2, so that the apparatus 1 is designed as a back pack load. The straps 2 are fastened by way of known "per se" fastening means in recesses 3 of a housing 4 of the explosive or training apparatus 1.

The housing 4 is substantially U-shaped (Figure 3). The limbs 5, 6 of the U-shape have hollow spaces 7, 8. Arranged in the hollow space 8 is a flooding tube 9 which can be filled with water by way of a known "per se" flooding valve 10. A layer 11, about 3 mm thick, of polyurethane foam is applied to the external surface of the housing 4.

An explosive charge or acoustic active device 13 is secured by threaded fastener means so as to be centrically intersected by a line of symmetry 14 (Figure 2) mid-way between the limbs so that an external surface of the device is co-planar with an external surface 1 5 of the housing to provide the apparatus with a planar abutment surface. The device 1 3 is housed in a free space 16, corresponding to device 13, which space 1 6 is provided in the housing 4 between a side wall 17, a web 18 and a chamber 19 for a detonating or actuating device 20. The device 20 is covered by a bolt on cap 21. The explosive charge or acoustic active device 1 3 and the detonating or actuating device 20 lie, in accordance with Figure 2, on a median cross-sectional plane 14' mid-way between the limbs and normal to the abutment face 1 5. This cross-sectional plane 14' intersects the centre of gravity 25 of the apparatus 1.

At right angles to the cross-sectional plane 14', rotatably mounted upon the housing 4 in a space 24 intermediate the limbs 5, 6 is a shaft 26 of combined fastening and clamping means 27, As shown in Figure 3, the apparatus 1 is applied to a target object, e.g. a girder 29, that is to be demolished, and is held to the object 29 by fastening means 28 (shown partially and diagrammatically in dot-dash lines) such as a chain or wire rope of the fastening and clamping means 27. The fastening means 28 is an integral component part of the fastening and clamping means 27. The fastening means 28 has, at its free end, a hook (not shown here) which can be grasped to facilitate the fastening means 28 being reeled off from the fastening and clamping means 27. In so doing, the fastening means 28 is taken in such a way that the explosive or training apparatus 1 lies within the fastening means.In this way, upon tensioning of the fastening means 28 by tensioning means (not shown) of the fastening and clamping means it is ensured that the apparatus 1 is clamped areally with its abutment surface abutting the object 29 so as to ensure surface to surface and not edge to edge or surface contact as far as possible depending upon the shape of the object.

The centre of gravity 25, lying in the crosssectional plane 14', of the explosive or training apparatus 1 make it possible for the frogman to relatively accurately pre-centre of the apparatus 1 on the object 29. Contributing to the ease of alignment is the fact that the apparatus 1 has, at the start of the transportation to the object 29, a slight negative buoyancy as a result of the flooding of the flooding tube 9, whilst the centre of buoyancy provided by the spaces 7, 8 remains near to the centre of gravity. This has the advantage that fastening means 28 only has to be unreeled to the necessary minimum length required to embrace the object and allow the hook to be reconnected to the apparatus, e.g. to the fastening and clamping mechanism 27.The required length of the fastening means 28 is therefore considerably shorter than would be in the case wherein the apparatus had an eccentrically-lying centre of gravity such as that indicated at the point 25'. An eccentric centre of gravity at the point 25' would, on account of the negative buoyancy tendency of the body 1, require to be brought into the median plane 30 of the girder 29 thus requiring a greater length of the fastening means 28 to be unreeled, which extra length would then have to be reeled in during tensioning in order to bring the apparatus to the depicted position of the explosive or acoustic device relative to the girder 29.

Upon detonation of the time-dependent or spark-impulse-dependent detonating means 20, the explosive charge of the device 1 3 is detonated in the direction of the girder 29. The explosive action destroys the girder 29 or leads at least to such damage to the girder that it is no longer functional.

If, instead of the explosive device 13, an acoustic active device 1 3 is provided, then the device 1 3 is started by way of an actuating device 20 which is used instead of the detonating device 20. The acoustic signals are so transmitted to and by the girder to enable persons to check that the training apparatus has been correctly applied and is working correctly.

The invention is not confined to the precise details of the foregoing example and many variations are possible within the scope of the invention as defined by the appended claims. For instance, the flooding tube may be moved closer to the middle of the apparatus. The small positive buoyancy is preferably only a few percent, e.g. 2 to 5 percent, of the dry weight of the apparatus, so that, for example, for apparatus weighing 30 kg the buoyancy is slightly less than 1 kg so that a flooding tube of, 1 dm3 capacity can be used to give a slight negative buoyancy of a fraction of the positive buoyancy of for example one kilo-gramme e.g. 10 to 500 grammes.

Claims (8)

1. An explosive or training apparatus for underwater use comprising a housing, an explosive or acoustic device, and fastening or clamping means for attaching the apparatus to an object, characterised in that the housing comprises a median portion disposed between buoyant portions; in that said median portion provides a first chamber in which the explosive or acoustic device is located so that an external surface of the device is substantially co-planar with an external surface af the housing to provide a substantially flat abutment face for the apparatus and so that a centre line of said median portion passes through said device; in that said buoyant portions define second and third chambers and project beyond said median portion to provide accommodation of recess form between said buoyant portions in which accommodation the fastening or clamping means is located alongside the median portion and in which accommodation at least part of means for actuating or controlling said device is located in operative connection with said device in said first chamber.

2. An explosive or training apparatus for underwater use, comprising a housing provided with internal chambers, of which a first chamber contains an explosive or acoustic device and a second chamber has means for admitting liquid, characterised in that the housing is of approximately U-shaped, thin-walled, metallic construction and has a flat and smooth abutment surface, the limbs of the U-shaped housing being of hollow form to provide the second chamber and a third chamber as buoyancy bodies; in that the explosive or acoustic device lies approximately centrically to a cross-sectional plane intermediate the limbs, so as to terminate flush with the abutment surface; in that a detonating or actuating device is disposed coaxially with the explosive or acoustic device at the rear of the first chamber of the housing, and in that fastening or clamping means, for securing the apparatus to a target object, is mounted on a shaft in a recess between the limbs.

3. An explosive or training apparatus as claimed in Claim 1 or 2, characterised in that recesses for strap fastenings are provided on the housing.

4. An explosive or training apparatus as claimed in Claim 1, 2 or 3, characterised in that the housing is provided with an external layer or coating of plastics material such as polyurethane foam.

5. An explosive or training apparatus as claimed in Claim 1, 2, 3 or 4, characterised in that a fastening means of the fastening and clamping means comprises a round steel chain or wire rope sheathed with plastics material.

6. An explosive or training apparatus as claimed in Claim 1, 2, 3, 4 or 5, characterised in that the air volume of the hollow cavities is sufficient to provide the apparatus with a small positive buoyancy in fresh water.

7. An explosive or training apparatus as claimed in any preceding claims, characterised in that only that one of the chambers which in use in the transportation position is normally lowermost is provided with a flooding valve and a flooding tube about 1 dm3 capacity.

8. An explosive or training apparatus substantially as hereinbefore described with reference to the accompanying drawings.