Unmanned Systems Technology 026 I Tecdron TC800-FF I Propellers I USVs I AUVSI 2019 part 1 I Robby Moto UAVE I Singular Aircraft FlyOx I Teledyne SeaRaptor I Simulation & Testing I Ocean Business 2019 report

34 O ver the past few years, propeller manufacturers across the UAS industry have expanded their focus towards the production of customised designs. That is partly because of the increasing maturation of UAVs and the growing competencies of their operators, who might approach a prop developer with a CAD model and ask them to provide the manufacturing, testing and analysis of the design. More and more manufacturers and users of small UAVs are also now aware of the value of using COTS propellers that have been designed and tested for airfoil and chord distributions appropriate for multi-rotor and fixed-wing UASs. Although such design considerations can drive up manufacturing costs, they are a key evolution among bulk producers of props the world over, as they come to understand more closely the unique air densities, power requirements, and operating conditions of UAVs versus those of RC hobby aircraft. At the same time, new markets such as aerial package deliveries, HALE pseudo satellites and self-piloted urban air taxis are spurring the development of larger propellers with customised geometries to serve their unique requirements. Each of these new types of UAS is different in terms of their flight envelopes, operations and potentially in their environments – none of which can realistically be served with COTS propellers in the way that small ‘prosumer’ UAVs can. Autonomous HALE craft and air taxis in particular cannot use existing COTS props, not least because of the expense and safety requirements. Development of robust and efficient propellers is critical for ensuring these vehicles can stay aloft safely and for longer. And since greater endurance can be translated into heavier payloads (or more passengers), an efficient propeller allows these new types of commercial operators to cater to more customers, for longer. Requests are therefore growing for propellers that are customised to suit specific parameters such as their aircraft’s mission, motor and environment. Even manufacturers of particularly high- end COTS propellers are now updating their bulk-produced designs with a modicum of aerodynamic analysis and testing to ensure a balance of efficiency between lift and hover, given that the Advances in materials, design and analysis are enabling UAV propeller suppliers to provide solutions tailor-made to a given application. Rory Jackson reports Made to order June/July 2019 | Unmanned Systems Technology More and more UAVs are using bespoke propellers that have been optimised for their specific mission, motor and operating environment (Courtesy of Mejzlik)