C4I: A quiet deployment | ADM Oct 2010
From the launch of weapons to acoustic countermeasures, hard kill torpedo decoys or rapidly deployed sensors, deployment of devices has always been a critical element of submarine operations.
Katherine Ziesing | Canberra
A number of methods exist to enable submarines to launch devices from countermeasures and decoys to sensors and flares, but each has its limitations.
Internal solutions such as submerged signal ejectors are well suited to deployment of distress beacons and flares but have limited salvo capability and require operator input for reloading.
Under-casing solutions are better suited to the rapid launch of multiple devices and can be quickly replenished between missions, but they impact on the platform’s mass distribution, and increase demand on the available under-casing space.
Those relying on pyrotechnic charges are also increasingly undesirable due to the difficult safety cases required when the submarine is alongside.
And solutions relying on gas discharge are often depth-dependent, with some only operating across a portion of the submarine operating envelope, and the release of gas can put the submarine at risk of detection.
Recognising these limitations and applying its extensive experience, Babcock has designed and developed an innovative scalable launcher to deliver new, improved capability, with an extended life and minimised through-life costs, while minimising any adverse impact on the platform in terms of mass or space.
The new design captures the system engineering philosophy developed by Babcock and utilised by its engineering team based in Adelaide.
This scalable, flexible launch system enables submarines to launch a range of different devices without compromising on stealth or operations.
The design avoids the traditional paradigm of existing launch methods and captures desirable features such as lightweight, modularity and simplicity.
Key components of the system are a launch tube, which stows the payload in dry conditions at atmospheric pressure, with a releasable nose weight at the front, and pusher at the rear; a firing tube containing the firing piston joined to the pusher via a cable which passes through seals between the launch tube and firing tube; and an air reservoir containing high pressure launch air and linked to the firing tube via the firing valve in the front manifold block.
On firing, the high pressure air enters the firing cylinder, forcing the piston down the length of the firing tube which pulls the pusher down the launch tube, ejecting the device.
As the pusher moves it reveals the flood ports, allowing follow-up water to enter the launch tube behind the pusher.
“The technology holds significant potential, both for retrofit and for new platforms,” Ken Grove Babcocks business development director points out.
“Extensive use has been made of mathematical models to inform and validate the design, and the launcher has been through a full programme of land-based physical testing, including full-scale trials of the system at our underwater test facilities on a 100mm and 200mm unit, as well as sea trials completed earlier this year.
“The results of all the physical trials have been used to validate the models, and the system has shown excellent correlation with our trajectory predictions.”
Importantly, the launcher can be scaled to launch any device (it has been developed to cope with small diameter changes and, more importantly, can be readily scaled for much larger diameters), and can be installed externally to the pressure hull under the casing of any submarine, in modules to offer the greatest flexibility, with rapid installation and removal.
Among the significant advantages offered over existing systems, Grove points to the fact that the system is inherently covert, in that there is no gas discharge (the launch air is contained within the firing tube after launch), and it is designed to achieve the required launch velocities throughout the operating depth envelope.
The use of high pressure air removes the need for pyrotechnic devices.
Additionally, no special stowage liquid is required as the device is stored in a dry condition, and flooding of the tube is an integral part of the launch function, making the launch a quick, sequential process.
Moreover, the compact, extremely lightweight design makes the system ideal for installation under the casing in multiple launcher modules.
“We have pioneered this modular design approach,” Grove said.
“The overall part count has been minimised with the firing and nose cap release mechanisms combined, and multiple launch tubes have been assembled into modules for ease of installation and replenishment.
“Weight has also been minimised with the use of light-weight composite materials to construct the main tubes.”
To meet the challenges of installation of existing submarines, the system allows launchers to be mounted individually or in packs of four to six, in cradles.
With no demand for support services from the submarine (only electrical cables, if required by the device being launched), the system lends itself to be considered as a retrofit to the Collins Class, the company is keen to point out.
The company is also keen on pitching the system to the Future Submarine under Sea 1000.
The launcher technology is currently being used to develop new torpedo countermeasure systems, including a soft kill countermeasure system and hard kill torpedo decoy system.
Being fully scalable, it also offers considerable future potential applications, from rapidly deployed sensors (offering vital covert salvo capability) to external weapon launch as a compact, tube-dedicated launch solution.