Uncrewed Systems Technology 051 l Primoco One 150 l Power management l Ocius Bluebottle USV l Steel E-Motive robotaxi l UAVs insight l Xponential 2023 p Issue 51 Aug/Sept 2023 art 2 l Aant Farm TPR72 l Servos l Tampa Deep Sea Barracuda AUV

54 Digest | Ocius Bluebottle USV panel sizes with as little dead space as possible, although the triangular shape of the bow has some wasted space. “However, a company called Praxis in southern Australia is customising the forward bow deck panels. That will give us about 30% more solar area on the hull. Our engineers aren’t certain we need that, but we’ll try it to see if it enhances our capabilities.” For storing solar energy, earlier versions of the Bluebottle integrated four batteries of 2.5 kWh each, whereas now the USV’s pack consists of six modules with 3.5 kWh each, for 21 kWh total, and with COTS products typically ordered from various European suppliers. The hull itself is fibreglass, and is currently carried out by Van Munster Boats, one of Australia’s leading naval architects. “We’re a displacement boat with no lifting surfaces, and we don’t go faster than hull speed, which is 5.8 knots, Dane says. “Really, weight is our friend, so carbon fibre is of no real benefit to us in terms of the outer hull. “The advantages of fibreglass, such as its water resistance, cost and other factors win out here. But the solar sail and decks are carbon fibre since those parts need to be lightweight and strong.” That lightness enables the Bluebottle to be launched and recovered by two people from a standard boat ramp, without a crane or other mechanical infrastructure. Dane notes, “This was born out of necessity: we didn’t have a lot of money in 2015, and not needing a crane has saved us fortunes over the years in operating costs. It also gives Bluebottle customers a low logistics profile.” Rudder-flipper Although the rudder section looks conventional (aside from its location beneath the bow), being a vertically disposed member extending down from the hull, the flipper protrudes as a perpendicular member from the end of the rudder, and resembles the flipper of a cetacean. As the USV pitches in the ocean waves, the flipper – being made of an undisclosed special flexible material – is deflected relative to the rudder, after which it oscillates in an elastic manner, back towards its original shape. The flipper has been designed such that the speed and motion in which its material oscillates are essentially synchronised to how fast and hard the Bluebottle is pitching in the waves. As the hull heaves up and down, the flipper also waves up and down, propelling the USV forwards as a whale or seal would be propelled by its own flipper. “Optimising that hasn’t been simple,” Dane says. “In the past we’ve tended to go back and forth on sizes and stiffnesses, but now we have a student doing a PhD on it. “For the rest of the gear we tend to get naval architect and boat builder advice, and then just put the boats out there until they break. Then we solve what broke, and repeat to see what else breaks.” Data links While comms such as payloads and computer electronics are user-defined from mission to mission, some data link systems are preferred by Ocius and are standard issue for the Bluebottle. “We have a high-bandwidth Certus system and a low-bandwidth IridiumGo – both satcom for BVLOS given our range and endurance capabilities. The highbandwidth link costs about AU$ 2000 per month, while Iridium’s is about $ 90,” Dane says. “Then we have radio, wi-fi and 4G cellular systems too, so as soon as we get within mobile phone range we can do high-bandwidth comms fairly easily.” Ocius has also used mesh radios from Silvus in its networked fleet and war games exercises for the Australian defence services, enabling radios on land systems and UAVs to communicate and coordinate movements with the Bluebottles, as well as relaying HD video and other dense payload data packets back to GCS operators. “In most cases though, satcom is what works best for us,” Dane adds. “We’re not trying to do any operations within 20 nautical miles of the coast, we’re aiming to provide capabilities hundreds of nautical miles BVLOS, where users would rather avoid using a crewed ship, as they’re expensive to obtain and operate, and it means unpleasant work and a long time offshore for the crews. Through satcom they can stay onshore and monitor as the USV works.” August/September 2023 | Uncrewed Systems Technology The Bluebottle’s patented flipper and rudder combination is the key to its wave-powered propulsion