The present invention relates to a shutter for a submarine countermeasure launch system as described in
As is known, submarines are equipped with countermeasure launch systems, which normally comprise a number of launch tubes with compressed-air firing systems, and are housed in an area of the submarine located between the outer hull and the pressure hull. The countermeasures are fired through shutters designed to permit rapid firing and in no way affect the streamline profile of the submarine.
It is an object of the present invention to provide a perfected countermeasure launch system shutter designed for reliable release and fast release and closure, and which does not affect the launch tube layout.
Further objects of the present invention are to provide a shutter that in no way affects the original streamline profile of the submarine, and of a mechanical strength in conformance with hull specifications.
According to the present invention, there is provided a shutter as claimed in Claim 1.
A preferred, non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:
Number 1 in
Launch system 2 comprises a number of air-powered launch tubes 3 housed in an area 4 located between an inner pressure hull 5 and an outer hull 6 of submarine 1, and which is therefore flooded.
Launch tubes 3 are arranged, for example, in two sets (only one shown), each sloping rearwards, with respect to the normal travelling direction of submarine 1, towards a respective side 7 of outer hull 6, and each comprising a number of superimposed rows of launch tubes 3.
Sides 7 of outer hull 6 have respective hatches 8 facing launch systems 2 and having respective openings (not shown) facing respective launch tubes 3 and fitted with respective shutters 9.
The following is a detailed description of one shutter 9 with reference to
Shutter 9 comprises a metal, e.g. stainless steel, supporting frame 11 substantially in the form of a surrounding frame and having an inner opening 12. In the example shown, frame 11 is a flat and rectangular with two long sides 13 and two short sides 14, and opening 12 is substantially rectangular.
Opening 12 has outer recesses 15 close to the ends of long sides 13, and each defined by a 90° arc 16 tangent to the inner edge of the adjacent short side 14, and by a sloping side 17, so that the inner edges 18 of long sides 13 of frame 11 are substantially in the form of an isosceles trapezium with the minor base 19 facing inwards of the frame.
Frame 11 has six fastening holes 20 edged on one side to form respective annular collars 21. Two of holes 20 are located along the centre lines of short sides 14, and the other four holes 20 are located in pairs on long sides 13, close to the ends of minor bases 19 of inner edges 18.
A cylindrical pin 22 is conveniently fitted, preferably force-fitted, inside a hole 23 located along the centre line of one of the long sides of frame 11.
Frame 11 also comprises a number of small-diameter holes 36 arranged along sides 13 and 14.
The shutter also has a cover 24 of elastomeric material, in which frame 11 is embedded.
More specifically, cover 24 comprises, integrally, a peripheral portion 25 covering frame 11 (with the exception of the inside of holes 20, the end surface of collars 21, and the end portion of pin 22 projecting beyond the axial length of collars 21); and a diaphragm 26 substantially closing opening 12 of frame 11. "Substantially closing" is intended here, not in the sense of sealing, but rather in the sense of restoring the profile of side 7, which would otherwise be interrupted by opening 12.
The peripheral portion (25) encases substantially the whole of frame 11, with the exception of the inside of holes 20, the end surface of collars 21 (with which the cover is flush), and an end portion of pin 22; and the elastomeric material inside holes 36 of frame 11 "bridges" the opposite sides of peripheral portion 25 to improve grip to frame 11.
Diaphragm 26 has a thin central portion 27 - more specifically, recessed on the collar 21 side - in the form of an isosceles triangle having a vertex 28 close to the centre line of a short side 14 of the frame, and two base vertices 29 at recesses 15 of opening 12 of the frame. Vertices 28, 29 of thin portion 27 are all rounded.
Respective small-diameter holes 30, 31 are formed just inside the vertices of the triangle, and a further hole 32 is located along the centre line of the base holes 31.
Portion 27 has two cuts 33, 34 respectively forming the height and base of an isosceles triangle having holes 30, 31 as the vertices: cut 33 joins hole 30 at vertex 28 to hole 32, and cut 34 joins the two base holes 31.
Cover 24 has a flat surface 35 facing outwards and flush with the outer profile of the submarine in use, and is conveniently made of a thermoplastic elastomer, preferably a polyurethane-based thermoplastic elastomer, such as that marketed by the trade name ADIPRENE® (Uniroyal Chemical Company, Inc. registered trademark). ADIPRENE® L-42, of Shore A hardness 75 or 80, or ADIPRENE® LF-1700A are preferably used.
The elastomer contains a curing agent selected from the group comprising 1,4-butadiene diol, trimethylolpropane, methylene-dianiline, dioctylphthalate, 4,4'-methylene-bis-(2-chloroanaline), and preferably a 4,4'-methylene-bis-(2-chloroanaline) marketed by the trade name MOCA® (DuPont De Nemours registered trademark).
To produce shutter 9, frame 11 is placed inside a mold, and the elastomer is poured into the mold by gravity.
After curing, cuts 33, 34 are conveniently made using a sharp blade, with no material removal, so that the lips of the cuts mate perfectly when diaphragm 26 is not stressed.
In actual use, shutter 9 is mounted facing a respective launch tube 3. Pin 22 acts as a locator to position the shutter, which is fixed to the side of the submarine by means of screws (not shown) through holes 20.
Tests conducted by the Applicant show shutter 9 according to the present invention provides for solving all the drawbacks typically associated with the known art.
In particular, cuts 33, 34 allow substantially instantaneous "release" of diaphragm 26 by the countermeasure as it is launched, and therefore substantially unimpeded passage of the countermeasure.
Once the countermeasure is launched, diaphragm 26 also closes substantially instantaneously to restore the streamline profile of the submarine; and shutter 9 produces no additional noise.
Shutter 9 easily complies with specifications governing the mechanical strength of hulls.
Shutters 9 also allow complete freedom in the layout of the launch tubes, depending on the space available on board.
Clearly, changes may be made to shutter 9 without, however, departing from the protective scope as defined in the accompanying Claims.
For example, as opposed to being flat, frame 11 may be shaped to match a curved profile of the outer hull of the submarine; and cover 24 may be designed accordingly, so that outer surface 35 is flush with the outer profile of submarine 1.
Each shutter may comprise one or more openings, and therefore one or more diaphragms.
The size and shape of the diaphragm/s may vary, depending on the layout and characteristics of the launch system.
For example, thin portion 27 of diaphragm 26 may be substantially rectangular; and cuts 33, 34 may differ in number and be replaced, for example, by cuts forming an H, i.e. two close to two opposite sides of portion 27, and a third joining the middle of the first two.
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.