GB2218393A - Disposable drogue system - Google Patents

Abstract

A disposable drogue system for umbilical cable deployment underwater comprises a tube 10 housing an outermost or operational drogue module 12a and successive follow-up modules 12b, 12c .... connected by breakable tie links 13. Each module 12 contains a pilot chute 14 and main chute 15. The tube 10 has a dilatable end region for module engagement and release. In use, the pilot chute 14 is actuated to deploy and draw out the main chute 15. Hydrodynamic drag on the main chute 15 is transferred via the tube 10 to the umbilical cable connected thereto. Sufficiently high drag on the main chute 15, effected accidentally or intentionally, results in release of the module 12a from the end region 19 of the tube 10. The respective tie link 13 then draws a follow-up module into the engaged operational position and finally breaks to disconnect the spent module. <IMAGE>

Description

DISPOSABLE IIROGUE SYS'FM This invention relates to drogue systems and in particular to 9 disposable drogue system. Drogues are well known and constitute essenti.ally a chute which in use is deployed to provide a resistance against movement through a fluid, usually air or water. Drogues may be used simply to stabilize an object being towed through a fluid or may serve to extract an object from a body moving through a fluid.

The drogue system of the invention is intended specifically, a1thn': not exclusively, for use in deploying an umbilical cable .mderwater from a vessel moving throngh the wster. Such.an umbilical cable might for example be part of a sonar array.

Conventionally such umbilical are attached to the vesbel at the comm.encement of a patrol once the vessel is clear of the confined space and shallow water of the harbour. This necessitates storing the umbilical on an attendant craft and arranging for the end of the umbilical to be transferred and connected to the vessel. in open water.

The vessel then steams away to pull the umbilical from its storage on the attendant craft. Upon completion of the petrol, the umbilical is jettisoned in a known position to be recovered later. This conventional system imposes many restrictions on the vessel's manoeuvrability. It is an object of the present invention to provide a disposable drogue system for unreeling an umbilical from a storage drum housed in a-free flooding space in the vessel, thereby simplifying the operation ofdeployment.

According to the present invention a disposable drogue system comprises a deployment tube for attachment to a deployable umbilical, an operational drogue module and at least one follow-up drogue module located within the tube, each module retaining a respective drogue chuLe, and module engagement and relate means associated with the tube and operative for module release at a predetermined drag exerted by the respective drogue chute.

Preferably the deployment tube contains a plurality of followup modules disposed successively along the tube. Conveniently the follow-up modules are arranged in axial alignment within the deployment tube in sequence following the operational module.

In one arrangement each drogue module may be connected with the respective follow-up module by a weak tie link strong enough to draw the follow-up module into the engagement and releaseXmeans but which will fail when subjected to tension from the released operational module.

The engagement and release means may comprise a convergent end region of the deployment tube against which the operational drogue module engages and which is dilatable under axial/radial stress to allow the drogue module to be withdrawn from the deployment tubs.

Advantageously the convergent end region includes logitudinal slots to facilitate dilation and module release.

Preferably the drogue module includes an outer peripheral surface region of ftuste.-conical from to engage with the convergent end region of the deployment tube. Conveniently the frusto-conical portion lies intermediate the forward body portion of the drogue module containing tae pilot chute and the main body containing the main drogue chute i.eans may conveniently be provided whereby the pilot chute of the operational module can be released remotely to initiate the deplo, ent sequence. In one arrargement the drogue module may include a release mechanism which is triggered by electrical or electro-magnetic meant.

Alternatively there may be provided mechanical linicage means operative to initiate release of the pilot chute of the operational module when, for example, the deployment tube is withdrawn into the vessel beyond its normal datum position.

In a preferred embodiment the disposable drogue comprises a deployment tube housing several drogue modules. The convergent end region of the deployment tube may conveniently be made of a suitable plastics material to give the desired spring release characteristi:s.

An embodiment of the invention will now be described, by way of e.vsimple only,with reference to the accompanying drawings1 in which:- Figure 1 is a part sectional elevation of a disposable drogue system of the invention showing four drogue nodules, Figure 2 is an enlarged part sectional elevatioiL of tha operational drogue module within the deployment tube, and Figure 3 is an enlarged part sectional elevation of the operational drogue module showing an alternative pilot chute release mechanism.

Referring initially to Figure 1 there is shown a deployment tube 10 located within an exit/entry passageway 11 in the vessel from which an umbilical cable (not shown) is to be deployed. The umbilical (not shown) is stored on a winch drum fitted in a free flood space of the vessel, the winch drum control ling deployment and recovery of the umbilical.

The. deployment tube 10 houses several, typically five, successively disposed drogue modules 12a, b, c ...., the outermost of which is referred to as the operational drogue module whilst the remainder are referred to as follow-up drogue modules. Each drogue module 12 is connected with the respective follow-up drogue module by means of a respective week tie link 13* The operational drogue module 128. is shown with its pilot chute 1 ar.st zain drogue chute 15 in their functional or deployment condition.

Revering now to Figure 2 the operational droge module 12a comprises a forward body portion 16 housing the pilot chute 14, a main body portion 1? housing the main drogue chute 15 and an intermediate body portion 18 of frusto-conical form which engages with a convergent end region 19 of the deployment tube 10. The convergent end region 19 includes longitudinal slots 20 to provide radial resilience to the convergent end region which is thereby dilatable. This allows the operational drogue module 128 to be withdrawn from the deployment tube 10 when subjected to a predetermined axial pull effecting appropriate dilation of the region 19.

A pilot chute 14 release mechanism 21 is located at the forward end of the drogue module 12 and is responsive electro-magnetically to a signal from a triggering mechanism 22 positioned in the fair lead region of the exit/entry passageway 11.

In operation, the disposable drogue system is attached to the free end of the umbilical and located in the exit/entry passageway 11 as shown in Figure 1. As illustrated, the frusto-conical intermediate body portion 18 of the operation drogue module 12a is in engagement with the convergent end region 19 of the deployment tube 10. To deploy the umbilical with the vessel under way, the pilot chute release mechanism 21 is activated and the pilot chute 14 released. The pilot chute 14 then withdraws the main drogue chute 15 from the main body portion 17.The main drogue chute 15 fills with water and creates a drag which is applied initially to the drogue module 12a, thence to the deployment tube 10 via the' frusto-conical intermediate body portion 18 and the convergent end region 19, and finally to the umbilical to effect deployment. X Figure 3 shows an alternative mechanism for releasing the pilot chute 14. In this embodiment the pilot chute release mechanism 21 includes rearwardly extending spring loaded arms 30 which are biased radially outwards. When the drogue module 12 is wholly within the deployment tube 10, the arms 30 are biased against the inside of the deployment tube 10. The arms 30 open out under spring pressure as stwn once the drogue module 12 is pulled in.to the operational position.

The deployment tube 10 in this emhodiment is not fully withdrawn into the exit/entry passageway 11 u:ti? it is desired to initiate release of the umbilical. At that time the umbilical and deployment tube 10 are withdrawn into the exit/entry passageway 11 until the extealdeu arms ;v) engage with the fair lead region of the exit/entry passageway 11 to initiate release of the pilot chute 14.

Whichever pilot chute 14 release mechanism is employed, its initiation leads to the progressive deployment of the umbilical.

The convergent end region 19 of the deployment tube is specifically designed to retain the drogue module 12 until a predetermined threshold axial pull force is exceeded. This axial threshold force sets a limit to the tension which the umbilical can experience, in order to avoid damage to the umbilical. If this threshold force is exceeded accidentally, or intentionally, such as for example by increasing the speed of the vessel, the operation drogue module 12a is withdrawn from the deployment tube 10 against the action of the convergent end region 19. The next follow-up drogue module 12h is then pulled into the outermost position and assumes the role of the operational drogue module 12a for the next deployment.The weak tie link 13 is sufficiently strong to move the followup drogue modules 12b, c along the deployment tube 10 into their respective new positions, but has a breaking strain appropriate to fail as soon as the frustoconical intermediate body portion 18 of the follow-up drogue module 12b engages with the convergent end region 19 of the deployment tube 10.

Once the umbilical has been rewound, the deployment tube 10 is repositioned within the exit/entry passageway 11 and the system is automatically ready for the next deployment, the relevant positions being different for the embodiments shown in Figures 2 and 3.

It will be readily appreciated by those skilled in the art that variations in design are possible whilst embodying the broa.d principle of the invention.

Claims (14)

WEAT I CIAIH IS:

1. A disposable drogue system comprising a deployment tube for attachment to a deployable umbilical, an operational drogue module and at least one follow-up module located within the tube, each module retaining a respective drogue chute, and module engagement and release means associated with the tube and operative for module release at a predetermined drag exerted by the respective drogue chute.

2. A disposable drogue system according to claim 1 wherein the tube contains a plurality of follow-up modules disposed successively along the tube.

3. A disposable drogue system according to claim 7 or 2 including a respective weak tie link connecting adjacent drogue modules, the link being adapted to draw a. tollow-up module into contact with the engagement and release means and thereafter to break under tension from the released operational module,

4.A disposable drogue system according to claim 1, 2 or 3 wherein the module engagement au; rczeaGe means comprises a resilient radially convergent end region of the tube, which region is dilabable bj axial and radial stress to allow release of the operational module.

Se A disposable drogue system according to claim 4 wherein the said end region includes slots disposed longitudinally' of the tube to facilitate dilation and module release.

6. A disposable drogue system according to claim 5 wherein the end region is made of plastics material appropriate for spring release characteristics.

7. A disposable drogue system according to claim 5 or 6 wherein each drogue module has an outer peripheral surface portion of frusto-conical form for conformable engagement with the flexible end region of the tube.

8. A disposable drogue system according to claim 7 wherein the said surface portion is intermediate the forward end main module body portions containing the pilot and main drogue chutes respectively.

9. A disposable drogue system according to any preceding claim 8 wherein the operational module pilot chute is releasable by a triggering irchanism located remotely of the module.

10. A disposa drogue system according to claim 9 wherein the triggering mechanism iselectro-magnetic, each drogue module having a complementary e)ectro-magnetically activatable meaus for pilot chute release.

71, A disposable drogue system according any one of claims 1 to 8 wherein each module includes rearwardly extending arms which are resiliently biased radially outwards against the tube, the arms being arranged to open upon movement into the operational position and being actuatable to deploy the pilot chute.

12. A disposable drogue system according to any preceding claim wherein deployment is initiatable by withdrawal of the tube from a datum position.

13. A disposable drogue system substantially as herein described with reference to and as illustrated in the accompanying figures 1 srsd 2.

14. A disposable drogue system substantially as herein described with reference to and as illustrated in the accompanying Figures 1 and 3.

14. A disposable drogue system substantially as herein described with reference to and as illustrated in the accompanying Figures 7 and 3.

CLAIMS 1. A disposable drogue system comprising a deployment tube for attachment to a deployable umbilical, an operational drogue module and at least one follow-up module located within the tube, each module retaining a respective drogue chute, and module engagement and release means associated with the tube and operative to release the operationsl module when a pre-determined drag is 'exerted by its respective drogue chute.

2. A disposable drogue system according to claim I wherein the tube contains a plurality of follow-up modules disposed successively along the tube.

3. A disposable drogue system according to claim I or 2 including a respective weak tie link connecting adjacent drogue modules, the link being adapted to draw a follow-up module into contact with the engagement and release means and thereafter to break under tension from the released operational module.

4. A disposable drogue system according to claim 1, 2 or 3 wherein the module engagement and release means comprises a resilient radially convergent end region of the tube, which region is dilatable by axial and radial stress to allow release of the operational module.

5. A disposable drogue system according to claim 4 wherein the said end region includes slots disposed longitudinally of the tube to facilitate dilation and module release.

6. A disposable drogue system according to claim 5 wherein the end region is made of plastics material appropriate for spring release characteristics.

7. A disposable drogue system according to claim 5 or 6 wherein each drogue module has an outer peripheral surface portion of frusto-conical form for conformable engagement with the resilient end region of the tube.

8. A disposable drogue system according to claim 7 wherein thi said surface portion is internediate the forward and main module body portions containing X ;t and main drogue chutes respectively.

9. A disposable drogue system according to claim 8 wherein the operational module pilot chute is releasable by a triggering machanism located remotely from the module.

10. A disposable drogue system according to claim 9 wherein the triggering mechanism is dectro-magnetics each drogue module having a complementary electro-sagnetically activatable means for pilot chute release.

11. A disposable drogue system according any one of claims 1 to 8 wherein each module includes rearwardly extending arms which are resiliently biased radially outwards against the tube, the arms being arranged to open upon movement into the opérational position and being actuatable to deploy * pilot chute.

12. A disposable drogue system according to claim 11 wherein opening of the arms is initiatable by withdrawal of the tube from a datum position.

13. A disposable drogue system substantially as herein described with reference to and as illustrated in the accompanying Figures 1 and 2.