Unmanned Systems Technology 021 | Robot Aviation FX450 l Imaging Sensors focus l UAVs Insight l Liquid-Piston X-Mini l Riptide l Eurosatory 2018 show report l Zipline l Electric Motors focus l ASTS show report

45 bending moment is not transferred from one craft to the next,” Cracau adds. The project’s ultimate aim is to launch and then interconnect ten separate UAVs, with a total payload of 450 kg spread across the ‘wingspan’ and flying at an altitude of 20 km for 365 days (with individual craft ‘sections’ being disconnected and replaced if the performance data flags up the need for any maintenance). Research is ongoing as to the optimal means for aerial docking between the system. Present methodology revolves around a combination of GNSS and optical sensors embedded and facing outwards from the wingtips. Having completed an initial concept test flight with three connected aircraft in June 2017, the next round of flight trials began in July this year and again involves three AlphaLink UAVs connecting and disconnecting in mid-air. The group plans to test a new model of connector produced using additive manufacturing to meet the exacting mechanical requirements for securing the wingtips between the UAVs while still allowing an element of movement in pitch and roll. On potential applications of AlphaLink and other HALE platforms, Cracau comments, “We’re interested in using this system to provide internet connectivity, as a hub or relay, independent of satellites or distributing satellite internet where there’s no ground-based infrastructure for telecoms networks. However, this market is not yet established on a commercial scale – long-term, remote observation is a more developed commercial market.” As Project AlphaLink develops its relatively small HALE solution, BAE Systems (in partnership with fellow UK company Prismatic) has also unveiled a concept for a larger solar-powered HALE unmanned aircraft, the PHASA-35. This is also designed to fly for 365 days, and have a 35 m wingspan and a 150 kg total weight. It is expected to begin flight trials in 2019. Now that Facebook has abandoned its 43 m wingspan Aquila UAV, to focus instead on its partnership with Airbus on HALE research, the PHASA-35 may soon have the largest wingspan of any HALE system in development. Hazard surveys Together with researchers at the University of Munich, Quantum Systems has used its newest (and smallest) UAV, the Trinity, to conduct medium- altitude survey missions over parts of the Chernobyl Exclusion Zone, the aim being to locate radiation-contaminated ground. While CBRN sensors have been developed that can be carried by a UAS (such as that seen in the partnership between Acecore Technologies’ Neo and Zoe multi-rotors and Flycam UAV’s DroneRAD sensor), they have to be flown at relatively low altitudes to be effective. That means less ground can be surveyed per hour compared with a medium-altitude craft with a higher vantage point. Higher flight would also give the ability to fly longer distances without going beyond the visual line-of-sight (as the short range of CBRN detectors would place a UAV equipped with such a payload barely above the treeline). Quantum Systems’ CEO Florian Siebel says, “We used an electro-optical [EO] camera on the Trinity, and we were hoping to see from the 3D model generated whether we could identify elevations that clearly weren’t congruous with the natural shape of the land. “These could indicate places where workers had rushed to bury radiation- contaminated earth when initially reacting to the catastrophe in 1986.” Such elevations were indeed found in the Trinity survey imagery, and matched the radiological data captured from quadrotor-mounted CBRN sensors. As a result, the aerial survey method has successfully discovered previously unknown trenches filled with contaminated earth, and the data UAVs | Insight Current solutions are built mainly on aircraft designs with a single-wingspan body, with a very long span to reduce the drag Unmanned Systems Technology | August/September 2018 The PHASA-35 high-altitude platform is an upcoming collaboration between BAE Systems and Prismatic (Courtesy of Prismatic)