LAUNCH AND RECOVERY OF UNMANNED VEHICLES USING A FLOATING-CRADLE: A SOLUTION THAT TRULY MEETS NAVIES’ MINE WARFARE (MW) NEEDS

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LAUNCH AND RECOVERY OF UNMANNED VEHICLES USING A FLOATING-CRADLE: A SOLUTION THAT TRULY MEETS NAVIES’ MINE WARFARE (MW) NEEDS

Navies are countering the threat from mines through next-generation systems

Mines are a major concern to navies. Their low cost and growing sophistication mean they’re increasingly a weapon of choice. Leading navies are exploring safer and more flexible solutions in the form of a “toolbox” of unmanned assets. To maximise flexibility and returns on substantial investments, they may need to operate such systems anywhere in the world, launching and recovering the toolbox’s vehicles from a mothership.

 

Launch and recovery from a mothership—taking navies’ needs to a new level

Handling unmanned vehicles from a mothership at sea introduces distinct and difficult challenges. Vehicles vary in shape and weight, and while some drone manufacturers offer individual options, none offers a Launch and Recovery System (LARS) that can handle a diversity of drones. Also, MW operations may be urgent, such as a need to rapidly clear a vital shipping lane. Navies can’t afford to be constrained by sea states, and a LARS that meets their needs must function perfectly in challenging conditions. Equally important is asset protection. MW’s complexity means sophisticated—and costly—arrays of sensors are fitted to vehicles’ hulls. These can rapidly sustain shocks in agitated seas, and a LARS must safeguard navies’ significant investments by robustly protecting sensors.

 

Conventional LARS options—a recipe for poor performance

There are two conventional LARS options: ramps, which descend into the sea at a ship’s rear, with unmanned vehicles mounting at speed and being hauled on deck using rollers and cables; and davits, deployed from the side, with unmanned vehicles travelling next to the ship as attempts are made to hook them up and crane them on board. Chantiers de L’Atlantique has analysed the potential of these conventional solutions in depth. While reasonably suited to launch, recovery is a quite different proposition. Putting aside the challenge of a ramp or davit that can handle a diversity of sizes and weights, the killer blow is dealt by the intrinsic linkage of these conventional systems to the mothership’s movements. In rough seas, motion (in all six degrees of freedom) can be significant—and the difference in size between the mothership and drones means their responses will also be different. As a result, securing them for recovery in agitated sea states becomes virtually impossible, and the shocks sustained can irreparably damage high-value equipment.

 

The Chantiers de L’Atlantique LARS: a dedicated design for the challenges navies face

Drawing on its considerable experience of naval and hydrographic projects, and in collaboration with offshore experts NOV-BLM, Chantiers de L’Atlantique has developed a dedicated solution to comprehensively meet navies’ needs. Its unique floating-cradle design blocks three degrees of movement (surge, sway and yaw) while allowing the other three. What’s more, the cradle and vehicle are of similar sizes—with similar movements. Combined, these features enable the LARS and vehicle to move together, yet semi-independently of the mothership—the key to positioning a vehicle for recovery. In addition, a system of fenders provides robust sensor protection, and under-hull slings, which can be tensioned and loosened easily, allow for rapid capture (or release) of vehicles. The combined effect is that an unmanned vehicle can enter the cradle to be secured and lifted onto the mothership’s deck in a matter of seconds. Chantiers de L’Atlantique has designed the LARS to operate reliably in Sea State 5, meeting a key operational need. And, rapid recovery minimises the vehicle exposure time during a delicate operation, protecting navies’ valuable assets and investments.