GB2608782A

GB2608782A - Underwater launch system

Info

Publication number: GB2608782A
Application number: GB9811922.5A
Authority: GB
Inventors: J Whiley Robert
Original assignee: BAE Systems PLC
Current assignee: BAE Systems PLC
Priority date: 1998-06-04
Filing date: 1998-06-04
Publication date: 2023-01-11
Anticipated expiration: 2018-06-04
Also published as: GB2608782B

Abstract

An underwater launch system 1 comprises a launch tube 2 and store 3 to be ejected from the launch tube by gas pressure. The store is surrounded by a free space 16, which free space is pre-flooded immediately prior to launch by operation of valve 12. The store may be a submarine countermeasure device having motor blades which are in a retracted position when the device is within the launch tube.

Description

AN UNDERWATER LAUNCH SYSTEM

The present invention relates to an underwater launch system of the type comprising a launch tube and a store to be ejected from the launch tube. More particularly but not exclusively, the invention relates to such a system for deploying submarine countermeasures such as sonar decoys/jamming devices.

In certain applications it is desirable to launch devices whilst underwater, for example sonar devices such as decoys or jamming devices from a submarine. Because it is desirable to minimise the number of apertures in the pressure vessel of a submarine such devices are normally housed between the pressure vessel and the outer casing of the submarine, which area is subject to harsh environmental conditions, the area being free flooding and therefore subject to both regular emersion in salt water and to any pressure waves incident on the submarine. Because of this and because such devices may have to be stored in a ready state for a considerable period of time, possibly years, they are typically stored in sealed launch tubes, each launch tube protecting the device (herein after referred to as a store) to be launched. The store is usually ejected by means of a gas generator, normally a pyrotechnic, located in the base of the launch tube generating gas which acts on a piston to force the store out of the launch tube.

The store may contain sensitive electronic circuitry which it is desirable to isolate from pressure waves incident on the launch tube, often of a re-enforced glass fibre composition. To provide such isolation it has been proposed to have a store of slightly smaller dimensions than the internal diameter of the launch tube and therefore provide a free space around the main body of the store, which free space can be a partial vacuum, air or an inert gas, the later being particularly advantageous in that it provides a desirable environment for the long term storage of electronic components.

According to the present invention there is provided an underwater launch system comprising a launch tube and a store to be ejected from the launch tube, characterised in that the store and launch tube define a free space within the launch tube which free space, prior to commencement of a launch procedure, is sealed from the water into which the store is to be launched, the launch tube comprising a valve arranged to open on commencement of a launch procedure allowing the free space to pre-flood with liquid at a pressure equal to the pressure of the water into which the store is to be launched.

The provision of a valve allowing liquid into the free space, at the same pressure as the water into which the store is to be launched, enables the store to be projected at a high velocity from the launch tube without problems arising from the in-rush of water that would otherwise occur with the breaking of the seal between the free space and the water into which the store is to be launched. This in-rush of water has been found to cause considerable damage to components of the store.

Preferably the valve is in fluid communication with the water and allows the water to pre-flood the free space. This ensures that the liquid (water) within the free space is at the same pressure as the water outside the launch tube.

Advantageously the system comprises a control mechanism arranged to receive a launch command signal and in response thereto to open the value a pre-determined period before the launch of the store, the pre-determined period being sufficient to permit the free space to flood before launch. This enables a single command signal to be utilised to commence a launch routine, which may be advantageous in enabling the system to be utilised with existing circuitry on board a submarine. Alternatively a relay could be used such that a first signal from the submarine actuates the valve and a subsequent signal triggers the launch itself.

Where the valve opens a pre-determined period before the launch, the pre-determined period can be dependent on pressure of the water or depth of the launch system. The greater the depth/pressure the faster the free space will flood and therefore at greater depths the period can be shortened. This maybe advantageous where it is desirable to minimise the delay in launching the store.

In an alternative arrangement a plurality of valves can be employed and the control means arranged to select the number of valves to be opened in dependence on the pressure of the water or depth of the launch system.

Preferably the valve is a pyro-technic valve for such valves are very reliable under long term storage conditions and require very little electrical current to trigger them.

A launch system employing a valve in accordance with the present invention is particularly advantageous where the launch tube comprises a gas generator, the gas from which acts on a piston to cause the store to be ejected from the launch tube, which piston may be an integral part of the store. With such systems the in-rush of water meeting the piston can cause considerable damage or require significant strengthening of the store/piston arrangement.

The present invention is advantageously employed in systems where the store comprises rotor and/or stator blades which when in the tube are housed in a retracted position in the free space. Any in-rush of water can tend to dislodge such rotors/stators causing them either to foul on the launch tube or to be dislodged such that they are subject to drag on emerging from the launch tube, which drag may cause further dislodgement and/or damage. Such arrangements are found on sonar devices which are propelled to their intended position by being ejected from the launch tube and then deploy the rotor and stator blades to control the depth of the sonar device.

One embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings of which: Figure 1 is a partial cross-section through a launch system in accordance with the present invention; Figure 2 is a side elevation of the store of Figure 1 when in a deployed mode, and; Figure 3 is a front elevation of the store of Figure 2.

Referring to Figure 1 an underwater launch system designated generally as 1 comprises a launch tube 2, (shown in cross-section), housing a store indicated generally as 3.

The launch tube 2 comprises a re-enforced glass fibre cylinder 4 sealed from water in the region 5 by sealing cap 6, which is sealed with the inner surface of the cylinder 4 by an 0-ring seal 7. The sealing cap 6 is retained in place by nylon shear pins 8.

At the closed end of the cylinder 4 is located an annular pyro-technic gas generator 9 which when activated generates a large volume of gas in region 10. The pyro-technic gas generator is activated by control circuit Il which control circuit 11 also controls operation of pyro-technic valve 12 via wire connection 13.

The pyro-technic valve 12 comprises a piston 14 (shown in a closed position), which on operation of the valve 12 permits water to flow from region 5 through opening 15 and 17 into a free space 16 between the store 3 and the inner surface of cylinder 4.

In operation a signal is received on control line 18 in response to which the control circuitry 11 sends a signal to the valve 12 causing the valve to open and permitting water in the region 5 to flood free space 16. At normal operating depths the pressure of water 5 is such that the volume of inert gas occupying free space 16 is compressed to such an extent that its volume is so small as to have negligible effect on the launch of the store 3. After a pre-determined period sufficient to enable the free space to be flooded, which may typically be 1 to 2 seconds depending on the dimensions of the valve opening and operating depths, the control circuitry 11 energises the gas generator 9 and the gas generator acts on piston 19 and associated seal 20 of the store causing shear pins 8 to fracture allowing the sealing cap 6 and store 3 to be ejected from the launch tube 2.

In the particular embodiment illustrated the store is a sonar device and the launch system may conveniently be mounted within the outer hull of a submarine, not shown.

As seen more clearly from Figures 2 and 3 the store comprises a main body portion 21, a plurality of stators 22, a rotor 23 and four rotor blades 24. Once ejected from the launch tube 2 inertia carries the store 3 to its intended destination where the store 3 hangs vertically in the water with piston 19 uppermost. The store 3 has a negative buoyancy and is maintained at the desired depth by operation of rotor 23. The flow of fluid caused by operation of the rotor 23 passes over stators 22 which act to prevent the main body 21 of the store 3 rotating.

Prior to launch, and for a period after the launch when the store is still moving at a significant velocity, the blades 24 and stators 22 are retained in a retracted position as shown in Figure 1. When launched from the launch tube pre-flooding prevents damage to them. Once the store 3 has substantially slowed after launch the blades 24 and fins 22 are deployed in a conventional manner.

It is to be noted that with reference to Figure 1 the store 3 is supported by a resilient mounting ring 25 and by piston 19. The rest of the store is surrounded by free space 15 filled with an inert gas and thus sensitive electronics within the store are substantially isolated from any pressure waves incident on the launch tube 2.

Although a launch system has been described for launching a store comprising a sonar device it will be appreciated that the function of the store is immaterial and that the invention is applicable to other launch systems within the scope of the appended claims.

Claims

CLAIMS1. An underwater launch system comprising a launch tube and a store to be ejected from the launch tube, characterised in that the store and launch tube define a free space within the launch tube which free space, prior to commencement of a launch procedure is sealed from the water into which the store is to be launched, the launch tube comprising a valve arranged to open on commencement of a launch procedure allowing the free space to pm-flood with liquid at a pressure equal to the pressure of the water into which the store is to be launched.
2. A system as claimed in Claim 1 wherein the value is in fluid communication with the water and allows the water to pre-flood the free space.
3. A system as claimed in Claim 1 or 2 comprising a control mechanism arranged to receive a launch command signal and in response thereto to open the value a predetermined period before the launch of the store, the pre-determined period being sufficient to permit the free space to flood before launch.
4. A system as claimed in Claim 3 wherein the pre-determined period is dependent on the pressure of the water or depth of the launch system.
5. A system as claimed in Claim 3 comprising a plurality of valves, wherein the control means is arranged to select the number of valves to be opened dependent on the pressure of the water or depth of the launch system.
6. A system as claimed in any preceding claim wherein the valve is a pyrotechnic valve.
7. A system as claimed in Claim 3 wherein the valve is opened by an amount dependent on the pressure of the water or depth of the launch system.
8. A system as claimed in any preceding claim wherein the launch tube comprises a gas generator the gas from which acts on a piston to cause the store to be ejected from the launch tube.
9. A system as claimed in Claim 8 wherein the piston is an integral part of the store.
10. A system as claimed in any preceding claim wherein the store and launch tube are arranged such that the free space, prior to flooding, substantially isolates a portion of the store from any shock pressure waves incident on the tube.
11. A system as claimed in any preceding claim wherein the store comprises rotor blades which when in the launch tube are housed in a retracted position in the free space.
12. A system as claimed in Claim 11 wherein the store is a sonar device which is arranged to be propelled to an operating position by being ejected by the launch tube and once in the operating position to deploy rotor blades to control the depth of the sonar device.
13. An underwater launch system substantially as herein before described with reference to, and/or as illustrated in the accompanying drawings.