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

26 longitudinal lenticular segments with welded seams. It included two flanges to which the carbon-fibre gondola baseplate was attached, along with eyes for the attachment of various tethers. The internal air bladder has a volume of 7 m 3 and is made from 250-micron polyurethane film. The construction of the flight surfaces harks back to the wood, fabric and bracing-wire aircraft of World War I, but using modern materials. The structural solution was defined by the University of Bristol working with the National Composite Centre (NCC), with most of the fabrication conducted by the NCC. Span-wise stiffness is provided by three tubular carbon-fibre spars, two near the front of the wing and one near the rear. Spaced along these spars are aerofoil-shaped ribs, with a lightweight foam sandwiched between thin carbon- fibre panels. This skeletal structure is wrapped in a thin skin to provide the aerodynamic wing shape, as shown in Figs. 2 and 3. The horizontal and vertical tail sections are identical, and exactly the same as the outer panels of the wings, thus reducing the diversity in the parts tree, simplifying manufacture and aiding interchangeability. The sizing of the wings, tail and control surfaces was determined through numerical (computer-based) simulation of the aerodynamic forces and in conjunction with a six-degrees-of-freedom flight control model. The tail components are held together on a tail-box frame that fits over the cone-shaped rear end of the fuselage and uses WrapToR composite truss structures developed by the University of Bristol, as shown in Fig. 4 (page 28). Power supply, storage and generation Having chosen to address the solution through the inhalation, compression and exhalation of air from the atmosphere, the realisation of a sustainable aircraft – in terms of an infinitely repeatable mass variation process, plus self- December/January 2020 | Unmanned Systems Technology Dossier | Phoenix UAS Construction of the flight surfaces harks back to the wood, fabric and bracing-wire aircraft of World War I, but using modern materials Figs. 2 and 3 – The skeleton of the flight surfaces are wrapped in a thin skin to provide the aerodynamic wing shape