75 its UAV demonstrator for that project at the show. In designing it, Darrah and his fellow engineers went with the most complicated configuration they could think of: a distributed propulsion arrangement with six electric propulsion motors on each wing and then two more on the tail, along with a tilting wing and tail VTOL-transition method reminiscent of the NASA Greased Lightning UAV demonstrator first flown in 2014. “It has six control surfaces on the wing, three in the tail, and a nose gear, each of which has its own individual servo, then the tilting tail uses a linear actuator, and a car seat motor is used for the tilt wing, as that was the lightest, strongest option we could find,” Darrah noted. The intended autopilot for the project did not arrive in time owing to a supplierrelated delay, so to get the aircraft into flight testing, the team had to change to Ardupilot, which is not meant to be used with the Mavrik-type configuration. However, with some modifications, the team effectively ‘tricked’ the UAV into thinking and operating as if it had a quadplane configuration. “We’re now making our own custom flight controller to better optimise the in-depth design,” Darrah added. “We’ve just made a flying duct UAV for another project, and the key to that was creating a unique flight controller from a blank sheet, so that’s something we’re doing more and more.” Plettenberg exhibited for the first time at Xponential, displaying a range of its electric motors, its Nova series of e-propulsion units attracting particular attention for potential integration in UAVs. “There are eight motors in the Nova product line, starting from 1 kW for smaller UAVs and going up to about 50 kW for heavy UASs or advanced air mobility OEMs,” said Bastian Greiner. “The Nova 15 is one of our top sellers, with 15-20 kW peak power depending on the length to which it is tailored,” he said. “We also have a close partnership with Mejzlik in supplying that system, which is critical because the efficiency of your UAV depends on the whole propulsion system – the right ESC matched to the right motor and the right propeller.” The Novas are closed-housing inrunner BLDC motors, which Plettenberg noted are especially popular among UAS integrators for their ruggedness across different environments. Most of the motors are IP54-rated for dust protection and splash tolerance as a baseline, but the company customises its solutions for higher protection classes and other parameters on request. “As well as needing to cover different ranges and speeds, UAVs these days have all sorts of different battery voltages, hybrid systems, internal ambient temperatures and other upstream considerations that you need to look at in order to optimise the propulsion system,” Greiner noted. “With our tailored propulsion systems, we achieve the best trade-off for power to weight to robustness, while maximising efficiency over the entire load profile.” Walking the aisles of the show was Armstrong Race Engineering (also known as Spintric Technologies), which specialises in fluid management systems. Although traditionally its customers have primarily been in motorsport, it has opened its doors to those in the uncrewed world, hence its presence at Xponential. “We’ve been in racing for over 40 years, particularly making dry-sump oiling and fuel systems, and consequently aerospace integrators have been asking us increasingly over the past several Xponential 2023 | Show report Uncrewed Systems Technology | August/September 2023 DARcorporation’s Mavrik demonstrator Plettenberg’s Nova 15 electric motor (closed housing view)
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