Uncrewed Systems Technology 044 l Xer Technolgies X12 and X8 l Lidar sensors l Stan UGV l USVs insight l AUVSI Xponential 2022 l Cobra Aero A99H l Accession Class USV l Connectors I Oceanology International 2022

26 Dossier | Xer Technologies X12 and X8 In particular, the X12’s and X8’s capabilities in heavy lifting, seamlessly switching in and out of stationary hovering, and environmental ruggedness, open up numerous mission capabilities that were previously challenging for some users to access or afford. Given its roots in monitoring transport hubs, long-distance inspections of large industrial infrastructure are a focal point for Xer’s UAV development. However, Skantze and his team are also starting to supply their UAVs to many other applications across Europe and beyond. “As one example, with our endurances, carrying capacities and high electrical supply capacities, we see a clear value proposition to coast guards, border control and other government agencies for constant monitoring of national borders,” Skantze says. “Furthermore, we can perform environmental monitoring at a fraction of the cost of some of the alternative high-end UAVs on the market. That entails several very different mission sets, such as tracking endangered species and poachers, or surveying the exhaust plumes from large container ships for regulatory compliance. “We’ve also connected with several search & rescue organisations for future sales, as well as the UN. For them, we are looking to start investigating how we might use the X12 and X8 to find landmines, using Lidar, IR or other sensing payloads. It would be fantastic to find that our aircraft can indeed help clear land of dangerous munitions.” Engineering challenges The two most critical targets for Xer’s r&d have been specific energy (energy-to- weight ratio) and energy density (energy to volume). While the company considers itself agnostic regarding propulsion technologies, it knew early on that it could not possibly hit the flight times it wanted on battery energy alone. “Even though there have been great advances in the specific energy of battery technologies since we started development, they have plateaued significantly in recent years, and we couldn’t take a wait-and-see approach for better batteries,” Skantze comments. “As far as zero-emissions options go, we initially had a serious look at hydrogen fuel cells, and there are now some excellent systems out there.” He adds however that while the specific energy of hydrogen gas is almost unbeatable, its energy density is lacklustre. Unless the hydrogen is liquefied or compressed to 700 bar (which makes certification of componentry difficult), large tanks must be used, which are difficult to fit inside a multi-rotor airframe. Also, the slow ramp-up rates of fuel cells compared with reciprocating and rotary IC engines, would hamper quick transitions between hover, cruise and top speed. “Gasoline has around 100 times the specific energy and energy density of lithium-ion batteries, which makes it viable for our UAVs,” Skantze notes. “Furthermore, gasoline supplies and engine parts are far, far easier to secure than those for hydrogen at the moment, although if the hydrogen economy continues its pace of advance over the next few years, that could potentially be enough for us to consider switching.” Arriving at this conclusion for the choice of power system – and for the various other onboard components – was by no means a linear path. Skantze describes the bulk of early r&d having been “garage engineering”, which eventually progressed into the professional laboratories and development processes used internally now. By ‘garage engineering’ he means that non-stop testing, iteration and analysis of different assemblies of UAVs were the order of the day between 2018 and 2021, with one 3D printer and some helpful suppliers of carbon fibre and CNC- machined aluminium providing new airframe pieces as needed. The team pursued how they might maximise flight times, resolve other key engineering or operational issues, find the best suppliers for their most helpful components, and learn from mistakes along the way. “For instance, one day we’d find our airframe was too weak, leading to vibrations and resonances that interrupted flight stabilities,” he recounts. “Other days we’d trial engines from certain suppliers and find they performed nowhere near what their data sheets claimed, or find that they June/July 2022 | Uncrewed Systems Technology Essentially, all the components in the X12 and X8 are reconfigured in-house after delivery, to meet Xer’s targets on cooling, vibration and power management