'Lightweight' UPS-style flywheels to power naval laser zappers

Naval 'leccy storage tech looks remarkably familiar

Stone wheel on hillside

Updated The Royal Navy and the US Navy have been testing a system of "lightweight" energy storage flywheels as part of a larger project to bolt laser cannon onto warships.

The Flywheel Energy Storage System (FESS), we are told by the UK's Defence Science Technology Laboratory (DSTL), "uses innovative high-speed and lightweight flywheels to provide high-power electrical pulses" for powering items such as the Dragonfire laser blaster currently being developed by British boffins.

During testing carried out both in Scotland and in America, the FESS was hooked up to a Power Hardware In the Loop (PHIL) simulation. As this link explains, PHIL means you attach a high output generator to a simulated real-world electrical load and then carry out useful testing – without the risk of damaging, say, a multi-billion-pound frontline destroyer or frigate.

Kyle Jennett, MoD tech lead for the Power Networks Demonstration Centre (PNDC) in Scotland, said in a canned quote:

"This test bed lets us connect real-world hardware, like the FESS, to simulated naval platforms to evaluate the impact on the ship during different operational scenarios. This testing can accelerate equipment development, de-risk integration challenges, and limit the need for costly shore demonstrators."

More information about PNDC is available on its website. Originally developed for the electricity generation and distribution industries, its testbed site can simulate 11kV overhead power lines and up to 5MVA of generation capacity.

The electrical demands of laser zappers are large, for the obvious reason. Although warship electrical generation capacity (drawn from diesel-electric gensets) is typically measured in megawatts, most of that electrical energy ends up being fed to the propellers in order to move several thousand tons of steel through rough seas at speeds of 30kts+.

In NATO practice, most frigates and destroyers (medium-sized fighting ships that launch missiles at each other, to oversimplify it) have two sets of generators aboard: the base level diesel-electric sets and gas turbines to enable high-speed sprints. It thus makes sense to be able to store that peak generation capacity for use in the laser zapper at the appropriate moment.

The technology has obvious applications for the, er, tech world. While flywheel UPSes are well known, the kind of technology that could one day power a multi-megawatt laser cannon could keep the lights on in a data centre or a critical office for a significant period of time.

With the naval emphasis of FESS being on light-weight and having a sufficiently small footprint to fit inside a cramped warship, the potential for crossover becomes obvious. ®

Update

DSTL's Andrew Tate told The Register:

"Each flywheel pod is very approximately 0.8m x 0.5m x 0.5 m which includes the flywheel and its supporting systems (perhaps an oven size!) – the system we tested can accommodate up to 6 of these pods, but in theory is scalable to any number of pods. We have also demonstrated that we could support up to 3.2MJ of stored energy per pod."

On the weight of the flywheel, he said that DSTL's boffins have built their flywheels using "a lightweight carbon-fibre rotor with impregnated magnetised particles so it can act as a motor and a generator," with the wheel running "at nearly 40,000rpm in a near vacuum." All up the whole assembly weighs 180kg, with the rotor itself being "man liftable".

Testing of the FESS involved checking its speed of response and capacity, and then feeding pulses of energy to it simulating a laser discharge.

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