GB2253376A - Marine marker float - Google Patents

Abstract

An air-launched marker float comprising a canister (1) in which are stowed a parachute (2), a flotation device (3) attached to the crown portion of the parachute, a beacon (8) mounted on the crown of the flotation device, means for ejecting said parachute, flotation device and beacon from the canister upon launch, electrical means (6) retained within the canister for providing power to the beacon via a cable (9) interconnecting the electrical means and the beacon and means for actuating the beacon on deployment of the parachute. The means for actuating the beacon conveniently comprises a switch included within the electrical means (6), the switch being arranged to be thrown when the rigging lines interconnecting the parachute and the canister become taut, the switch actuating either a power supply for the beacon or a timing device to initiate intermittent operation of the beacon. The switch may be in the form of a reed switch thrown by the removal of a small magnet (5) attached to a rigging line which in the inoperative state holds the switch closed. <IMAGE>

Description

MARINE MARKER FLOAT This application relates to markers particularly suitable for use with air-launched marine floats and used, for example, to expedite the rescue or recovery of personnel or stores, such as sonobuoys.

Conventional marker floats use pyrotechnic materials such as phosphorus which are for many reasons hazardous. In addition, the materials can have an insufficient life for some operations and the smoke and flames produced can prove difficult to see, especially in high winds when the smoke can be quickly dispersed and lost amongst white water and spray. In light winds the smoke does provide a useful indication of wind direction but this is of limited use to a modern aircraft equipped with inertial navigation and and doppler equipment, which can give an accurate display of wind vector.

This invention consists of an air-launched marker float comprising a canister in which are stowed a parachute, a flotation device attached to the crown portion of the parachute, a beacon mounted on the crown of the flotation device, means for ejecting said parachute, flotation device and beacon from the canister upon launch, electrical means retained within the canister for providing power to the beacon via a cable interconnecting the electrical means and the beacon and means for actuating the beacon on deployment of the parachute.

The beacon conveniently incorporates a xenon flash tube; this tube can operate for a substantially longer period than pyrotechnic beacons, it has a distinctive flash of high intensity which is easily distinguished from spray and foam and it is much safer to store and operate, being essentially inert.

The means for actuating the beacon conveniently comprises a switch included within the electrical means and attached to a rigging line interconnecting the parachute and the canister, the switch being arranged to be thrown when the rigging line becomes taut.

The switch may activate either a power supply for the beacon or a timing unit for controlling intermittent operation of the beacon.

The parachute is preferably of the ram-air type and the flotation device may include a non-return valve to minimise deflation caused by wave action following impact on the water surface, for example one of the types described in UK patent applications, nos 8913961 or 9027360.8 The canister preferably contains anchoring means separable from the canister upon impact with the water surface; such means may comprise a folded, mooring anchor connected to the canister by a mooring line, or alternatively a sea anchor drogue.

By way of example, one embodiment of the invention will be described with reference to the d'rawing, which is a schematic elevation of an air-launched marker beacon constructed in accordance with the invention and shown during descent, ie after launch but before impact with the water surface.

As shown in the drawing, the beacon consists of three main components, a canister 1 having a conventional wind flap, a parachute 2 and a ram-air inflated float 3.

Prior to launch from an aircraft, the parachute and float are stowed in the rear, flap end of the canister in such a manner that after release the wind flap acts to pull the float and parachute from the canister before breaking a thread tie and flying free.

The parachute is of the cruciform type, and is attached by rigging lines d to the canister, at least one of the rigging lines being attached to a small magnet 5 which in its normal position holds open a reed switch in an electronics unit 6 contained in the canister.

The float 3 is attached to the parachute via a non-return valve 7 at the parachute crown and supports at its upper end a xenon flashing beacon 8.

The beacon is connected via a power line 9 to the electronics unit 6 housed in the canister and containing the necessary high voltage supply and timing mechanism for the beacon.

After release from the canister, the parachute deploys and the float inflates. As the parachute rigging lines 4 pull out of the canister during deployment, the magnet 5 is withdrawn so that the reed switch closes, activating the timing mechanism for the beacon which hence starts to flash.

On water entry, the canister containing the electronics unit, being negatively buoyant, sinks and is supported beneath the surface by the float, via the then collapsed parachute and the rigging lines. Also on water entry, a buckle plate 10 deforms to allow the deployment of a sea anchor drogue 11 hitherto stored within the front end of the canister.

The equipment described above can be very compact, and able to be contained in the smallest current ("F") size canister and would therefore be compatible with all current aircraft types capable of launching sonobuoys and would in addition be small enough to be hand launched, for example from the door of a non-tube equipped helicopter or light aircraft for civil applications.

The unit could easily be designed to produce a defined sequence of flashes to enable different markers to be identified after release. The sequence could either be fixed at manufacture or be incorporated into each marker as a programmable feature via a watertight selector switch set before release. Further differentiation between markers could make use of coloured shields or lenses to give each marker beacon a unique colour.

A prototype unit has been constructed using a xenon flash tube and electronics unit having an energy of 7.5 joules per flash and a flash rate of 1.5Hz. This has a mean power consumption of 2.2 amps which with the rechargeable batteries used results in an operating life of 50 minutes.

By use of lithium batteries as the power supply instead of rechargeable batteries, the operating life could be extended to about 12 hours without incurring any volume or weight penalty, and a further substantial increase in operating life or brightness could be made if the space occupied by the anchor were used to accommodate larger batteries. The storage life using lithium batteries would be better than 5 years.

In practical applications, the canister could contain a deployable anchor which together with a programmable flash sequence and different flash colours as aforesaid would enable the device to be used to provide a temporary navigation or hazard marker. It could also be used in such a form as a flexible programmable marker for training exercises.

Besides use with a flashing visual beacon, the unit could of course incorporate an aural warning, which could sound continuously when actuated or could emit an intermittent sound under control of a timing unit in the manner described above.

The cost of the basic units described above would be reasonable as the electronic components are relatively cheap and the parachute and float assembly are similar to existing proven designs for sonobuoys.

Claims (8)

1. An air-launched marker float comprising a canister in which are stowed a parachute, a flotation device attached to the crown portion of the parachute, a beacon mounted on the crown of the flotation device, means for ejecting said parachute, flotation device and beacon from the canister upon launch, electrical means retained within the canister for providing power to the beacon via a cable interconnecting the electrical means and the beacon and means for actuating the beacon on deployment of the parachute.

2. An air-launched marker float according to Claim 1 in which the means for actuating the beacon comprises a switch included within the electrical means and attached to a parachute rigging line, the switch being arranged to be thrown when the rigging line becomes taut.

3. An air-launched marker float according to Claim 2 in which the switch is arranged to activate a power supply for the beacon.

4. An air-launched marker float according to Claim 2 in which the switch is arranged to activate a timing unit for controlling intermittent operation of the beacon.

5. An air-launched marker float according to any preceding claim in the beacon incorporates a xenon flash tube.

6. An air-launched marker float according to any preceding claim in which the the flotation device incorporates a non-return valve to minimise deflation after impact with the water surface.

7. An air-launched marker fldat according to any preceding claim in which the canister contains anchoring means which are separable from the canister upon impact with the water surface.

8. An air-launched marker float substantially as hereinbefore described with reference to the drawing.