Unmanned Systems Technology Dec/Jan 2020 | Phoenix UAS | Sonar focus | Construction insight | InterGeo 2019 | Supacat ATMP | Adelan fuel cell | Oregon tour | DSEI 2019 | Copperstone Helix | Power management focus

23 apparent, though limited, success but was sufficiently promising to lead to a follow-on project supported by the UK’s innovation agency Innovate UK, and the UK’s Aerospace Technology Institute, which contributed 50% of the total project budget. The partners who formed the Phoenix project team comprised four private companies, three of the UK government’s high-value manufacturing catapults and five universities. The project lasted three-and-a-half years – a rather sporty timescale in which to design, build and test a new aircraft, along with the development of many of the constituent technologies, most of which were bespoke solutions for this application. Very few partners had previous aerospace experience, and only one had a track record of successful aircraft design, but each brought specific expertise, together with a wonderfully positive attitude, that helped achieve the final successful result. The project partners are listed in the sidebar on page 32. The project management role was performed by CPI (the Centre for Process Innovation) while the role of chief engineer was performed by the University of the Highlands and Islands (UHI) in Scotland, using a ‘parts tree’ approach that captured the weight, size and power requirements of each component on the aircraft. The philosophical approach chosen for the Phoenix differed fundamentally from that originally proposed by Solomon Andrews (see sidebar: The propulsion concept). Here, it was to achieve variations in buoyancy through a reversible change in aircraft mass without the need to jettison any ballast other than compressed air. The otherwise buoyant, lighter-than-air aircraft achieves a reduction in buoyancy by inhaling and compressing air from the external atmosphere into an internal ‘lung’ to add mass and make it heavier than air, and then exhaling that compressed air to return it to a lighter-than-air state, as shown in Fig. 1. It is tempting therefore to anthropomorphise the aircraft as a creature that breathes, inhaling and exhaling as it propels itself forward. Aerodynamic design The aerodynamic design of the fuselage and flight control surfaces was managed by UHI. Although the prototype developed within the project was designed to fly very slowly, it was also designed with an eye on future operations. One aspect of this approach was Phoenix UAS | Dossier Very few partners had previous aerospace experience, but each brought expertise that helped achieve the final result Unmanned Systems Technology | December/January 2020 After its ‘day job’ as storage for pleasure boats was over, The Drystack building hosted the first successful demonstration of the Phoenix Fig. 1 – The Phoenix achieves its sinusoidal flightpath by ‘inhaling’ and compressing air from the atmosphere, then ‘exhaling’ it