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

30 Dossier | Aergility ATLIS The cargo hatch at the rear is manually operated. The tail latches onto the undercarriage, and lifts after being unlatched, with gas struts for assisted lifting. Latched side doors also open as needed for parcels. The cargo bay is designed for VDA 4500 standard containers, also called EURO containers or KLT boxes optionally loaded on a 1200 x 800 mm EURO pallet [or EPAL]; two EPALS or four of the EURO 800 mm x 600 mm containers will fit end-to-end inside the production cargo bay. For flight safety, the ATLIS will not take off with a payload whose centre of gravity (CoG) is outside allowable ranges. To simplify loading, Aergility is also considering using a CoG-balanced pod that could be loaded and slid into the cargo bay on rails to secure it or even auto-latch it in place, with smart carts to assist loading and load cells to confirm that the CoG and weight distribution are acceptable before loading. MAT dynamics In addition to managing the ATLIS’ attitude control, the various electric rotors are also key to the net power consumption (or generation). “When the UAV tilts back a little, it’s in full autorotation,” Yonge explains. “At that point, you can put the nose down a bit and put just a little power into the motors to maintain their rpm, either directly from the battery or indirectly from the engine/ generator. That gives you the ATLIS’ most efficient flight mode. “You can tilt the aircraft further back, to have the wind drive the rotors harder and get the motors generating net positive power for the battery. That recharges the electric power without engaging the engine/generator, but it is more efficient to use the small engine-mounted generator to recharge the batteries. “Rotor braking is a fallback mode, should the power from the generator be unavailable. Our core competencies are built on the necessary control loops for managing attitude and power simultaneously through this motor network.” This system thus enables the ATLIS to fly with net-zero electrical consumption over the course of flight. For example, if the UAV banks right, the power management system powers the left rotors to lift the left wing, and depowers the right rotors to dip the right wing. In this instance, the three right-hand rotors are past autorotation, and are generating electric power, but the left- hand motors are consuming no more power than that being generated by their counterparts. “It’s the same across pitch and yaw,” Yonge says. “If you don’t attempt any unnecessarily strong manoeuvres, you can fly, climb and descend at zero electrical power, although fuel is of course being burned by the propulsion engine. “Perhaps most significantly for safety purposes, if the engine should ever fail, or human error causes you to run out of fuel, the ATLIS can glide on its wings like an aeroplane, with the rotors autorotating all the while thanks to the flight controller keeping the pitch attitude correct for the descent angle of glide. “It’ll consume no power until it needs to land vertically, at which moment its battery reserves should be either preserved or replenished enough that the rotors can be powered on to accomplish a gentle emergency landing that keeps the cargo undamaged.” Another key aspect concerns the point of VTOL transitioning, which can be a headache for engineers to program smoothly into a flight controller’s logic. Fortunately, the ATLIS does not technically have a transition state; it takes off with its rotors at full power, the forward propulsion engine is applied, and the rotors are gradually powered down as the UAV moves forwards (as per a helicopter’s flight behaviour). As it moves forwards, the rotor power continues to decrease, and the flight controller manages that declining curve to autorotate at low or high speeds depending on aircraft pitch. “It’s basically all one state, instead of being two separate states of flight – one vertical, the other horizontal – so we avoid that perennial tricky transition point sticking between them and all the difficulties of tiltrotors or hard power switching that comes with it,” Vander Mey explains. “It’s rather a smooth transition ‘curve’ as the power going to the motors decreases. For instance, if you wanted to fly slowly but not in autorotation, the rotors would need to consume a small amount of power.” December/January 2023 | Uncrewed Systems Technology Latched side doors open as needed for easier loading, unloading or strapping down parcels