Uncrewed Systems Technology 047 l Aergility ATLIS l AI focus l Clevon 1 UGV l Geospatial insight l Intergeo 2022 report l AUSA 2022 report I Infinity fuel cell l BeeX A.IKANBILIS l Propellers focus I Phoenix Wings Orca

98 U ncrewed systems have evolved over the past few years, leading to commercial, high-end UAV manufacturers attracting investment and setting up partnerships with organisations in markets including logistics, energy and defence. These operators need increasingly large uncrewed fleets, with similarly large inventory requirements to suit their cargoes and payloads. The same applies to USVs and UUVs, although perhaps not to the same extent. At the same time, the burgeoning eVTOL industry has spawned hundreds of companies designing aerial taxis, ambulances and other aircraft with distributed lift systems reminiscent of UAVs, and they will all be expected to be aerodynamic and energy-efficient. That puts significant pressure on propeller researchers and manufacturers, who are being asked by uncrewed and autonomous system OEMs to discover new ways of supplying products that generate lift and propulsion with smaller carbon footprints and greater lifespans than ever, and to enable these new classes of vehicles to be scaled up. Air taxi manufacturers in particular want ever-larger propellers – with diameters of about 2-3 m – to ensure enough lift can be produced without needing prohibitively fast prop tip speeds, as these would create unbearable levels of noise for the passengers, not to mention losses in energy efficiency. Furthermore, the air taxi industry’s determination to reach market readiness as quickly as possible is pushing lead times for large propellers, with prototyping now expected in some circles to take only 6 months compared with the 2 or 3 years it can take in general aviation. These eVTOL propellers also feature much more complex designs than have been seen in more typical autonomous aircraft. UAVs for delivery and inspection, for example, use more advanced props now than 5 years ago, using scimitar shapes, upturned and downturned winglets on blade tips, and even featherlike serrations on trailing edges. Also, a wide variety of resin and fibre systems in the propeller structures achieve different combinations of structural, aerodynamic and loading properties. But as air taxis will carry multiple passengers per flight, their props are almost certain to come with innovations such as leading-edge protection, internal structures using foams and other fillers, and potentially up to 100 layers of carbon fibre. And as might be expected from the safety case, greater testing and scanning of props are anticipated. With that in mind, UAV propeller manufacturers have adopted validation techniques from general aviation and incorporated them into their design and production processes. Rory Jackson finds out how prop suppliers are meeting the growing demands from OEMs for products that generate greater lift and with longer lifespans December/January 2023 | Uncrewed Systems Technology Upward and onward As autonomous systems increasingly carry valuable cargo and passengers, propeller testing and validations are becoming more rigorous (Courtesy of Mejzlik)