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8 Platform one February/March 2018 | Unmanned Systems Technology Airbus is working with a range of UK companies, including Williams Advanced Engineering (WAE), on new technologies for its lightweight, solar-powered Zephyr UAS (writes Bianca Villiers). The Zephyr is designed to fly above commercial aircraft, at 65,000 ft, filling the gap between satellite technology and UAVs as a High Altitude, Long Endurance (HALE) system. The latest generation of it can fly for 45 days to provide comms and surveillance, but the aim of the Zephyr Innovation Project (ZIP) in the UK is to extend that to months at a time by using lighter materials and enhanced batteries. WAE will use its experience from Formula E electric road racing to develop new battery systems and composite materials. This is alongside the £3.6m ZIP programme, where Oxis Energy, in England, is developing battery cells using lithium-sulphur chemistry to give an energy density of 400 Wh/kg, which can be up to five times more than today’s lithium-ion battery cells. The cells have to be integrated into lightweight battery packs with customised battery management technology from Williams. At the same time, composites company Formtech is working on new materials to reduce the weight of the Zephyr airframe from 50 kg, while another UK company, Productiv, is working on the motors for the craft. All of this work should be completed in time for the WRC2020 world radio conference in 2020, where new frequencies are expected to be allocated to support these high-altitude systems. Airborne vehicles Battery boost for HALE UAS The solar-powered Zephyr can fly for up to 45 days at a time Chinese inventors have come up with a semi-submersible unmanned ‘catamaran’ – actually more like a twin-hull submarine – that can shelter underwater from bad weather or detection by a hostile force. It leaves only a sensor head above the surface (writes Peter Donaldson). Its above-water sensors are fixed to a circular platform on top of a telescopic mast, which is supported by the pair of hulls that in turn are joined by an intermediate connecting structure. The mast is raised or lowered by a screw mechanism that is turned by an electric motor through a reduction gearbox. That is mounted in the main control chamber that itself is fixed to the underside of the connecting structure. The chamber also contains a battery and an autopilot, as well as the electronics for the above-water sensors. These would include cameras, a comms system, a Beidou navigation receiver, a depth-gauging system and underwater sensors such as side-scan sonar. Each hull has a domed bow, a cylindrical mid-section and a conical tail section that terminates in a rudder and a propeller. The hulls also contain fore and aft ballast tanks, each with its own leak detector. Each mid-section contains vertical and horizontal axis gyros, a servo motor, a dive tracker, wiring and a sealed tube for the hydroplane shaft to pass thorough. The rudder and propeller mechanisms and controls are at the end of the stern section. A pair of depth-control hydroplanes are mounted on a shaft that runs through both submarine hulls and the connecting channel between them. They are actuated by a second reduction gearbox driven by its own electric motor. A USV that sinks for safety Unmanned vessels