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

105 Propellers | Focus run inspections of them to identify how the materials and coatings respond to different applications of forces, wear and other inputs over time. Some prop makers are even borrowing the approach from manned helicopters of running tensor meters inside their blades to collect data on how the propellers bend and twist across their blade lengths in response to winds, strikes or other stresses. Such projects open up valuable insights into how prop mechanics and lifespans could be enhanced. These collective improvements in manufacturing and testing could result in up to a threefold increase in overall production costs. But the real net outcome is a lower total cost of ownership and price per flight given that they will result in an increase in lifespan of more than 10 times per propeller, so long as vehicle OEMs ensure all the other onboard components and software do their job in ensuring safe operations until a platform’s next repair or overhaul date. Simulation tools While propeller testing approaches are becoming more varied and in the number and precision of their data points, the maturity of propeller technology is such that advances in simulation tools and methodologies are critical to unlocking the kinds of step-improvements in prop efficiency that could pose a breakthrough for autonomous systems and manufacturers. However, while the benefits of distributed lift systems such as multi- rotors and VTOL-transitioning craft are closely understood across the autonomous space, the design rules, dynamics and heuristics are not yet captured in a single, universally applicable, high-fidelity CAD or CFD software solution that new aircraft developers can use when beginning the design process for a new vehicle. Finding the optimal rapid, design- order tool suite for early concept work is therefore extremely challenging, with programs such as SolidWorks, STAR- CCM+, OverFlow and more potentially being appealing choices, with various advantages and disadvantages to solve the many issues that can be faced at the outset of a new vehicle’s r&d. For example, and as discussed, eVTOL aircraft manufacturers have to contend with significant lead times when prototyping new propellers. It becomes even more challenging for them when designing more complex thrusters such as ducted fan arrangements, which could make for highly efficient propulsion systems. As a result, some new programs are aimed specifically at simulating ducted fans for VTOL-capable air taxis and UAVs. Their aim is not necessarily higher fidelity or lower error in simulation results, but more in the sense of modelling at a faster rate and more intuitively, to save time in their use and the training requirements for getting the best from the software. In addition to simulating individual prop, rotor and thruster designs, other projects are investigating how all-new distributed lift configurations – with motors, wings and propellers arranged in entirely untested permutations – can be optimised for qualities such as energy efficiency, noise, speed and structural resilience. One such project, publicised in mid-2022, investigated a UAV with tilting fixed wings and multiple rotors along its wings’ leading edges, looking at different positions of its motors with respect to its wings. Conclusion Well-established production and testing processes from the aerospace and automotive worlds are being deployed to enhance propellers in the rapidly maturing uncrewed vehicles industry. At the same time, software engineers are using a wide variety of algorithmic approaches and engines to perform their CFD work as well as optimise their quality control and validation of prototype and production propeller units. As a result, many high-quality propeller solutions are becoming available to uncrewed vehicle OEMs. Acknowledgements The author would like to thank Tomas Mejzlik Jr at Mejzlik, Markus Tack at Fichtner & Schicht, Nicole Wan at T-Motor, Leo Ko at Xoar International, and Willem Anemaat at DARCorporation for their help with researching this article. Uncrewed Systems Technology | December/January 2023 With time, the accumulation of data and use of AI allow more reliable, detailed and creative simulations of different blade geometries and combinations (Courtesy of Mejzlik)