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77 Commercial UAV Expo 2019 | Show report version called the Stella Pro CL 5000d. As Karl Lindstrom told us, “For the larger lights, a supply 13-25 V DC is needed at 100 W. We make our own proprietary batteries for the smaller lights to provide them as turnkey systems, and also so that we can design our own connectors to allow them to be flown in the rain.” The 10000d also comes with an integrated fan for cooling, to help package the electronics and LED in a 10.4 x 8.9 x 8.9 cm space without overheating, although Lindstrom noted that most UAVs provide enough ‘rotor wash’ to make the fan unnecessary. To that end, fan-less prototypes are in development. “The cinematic world is increasingly asking for UAVs that can provide 20- 40,000 lumens at altitude and angle, since that’s what it takes to light up a movie set from 250 ft overhead. It would therefore be ideal to mount two to four of these on a heavy-lift UAV in a payload weighing from 1.5-3 kg to satisfy that demand,” he added. TerraView unveiled its RangePro X8, a multi-rotor UAV designed to fly for 70 minutes –potentially more, depending on payload weight – in industrial, first responder and government enterprise and services applications. “UAV end-users are most concerned with safety, durability and return on investment,” said Bruce Myers. “That’s why we aimed to engineer the RangePro X8 with a longer flight time than most UAVs, and built it with materials to Mil- Spec standards.” The UAV’s 6S4P battery pack provides a 22.2 V supply, with 24,000 mAh of capacity and 532.8 Wh of energy. The four coaxial motor pairs, from T-Motor, each give a 3:1 lift-to-weight ratio and contribute to a maximum flight speed of 90 kph, as well as resistance to winds of up to 16 m/s. The RangePro X8 weighs 4.4 kg without its payload, and has a recommended MTOW of 7.5 kg. It measures 780 mm across and 310 mm in height, although it can be folded down and have its propellers removed to reduce its size to 460 x 265 x 150 mm. It can come integrated with a Pixhawk or A3 autopilot, as well as a DJI Lightbridge 2 video downlink (operating at 5.8 GHz, 2.5 GHz or 920 MHz), or a 2.4 GHz Herelink video downlink, or one specified by the end-user. Alva Industries told us about the technologies it uses in its radial flux electric motors. “We haven’t reinvented the electric motor, but we have found a new way to make them, and this production method improves the properties of electric motors by greatly increasing the copper fill factor in the stators, enabling much more current to be run through them,” said Knut Nielsen. “After three years of r&d, this has resulted in a system that can produce three times the torque of an ironless electric motor of equivalent size and weight. We’ll soon be rolling out our first two commercial products, which are certified to US and European standards.” The proprietary and trademarked production method has been named FiberPrinting, and uses machines that were developed in-house. The nature of the copper stator ‘ring’ manufactured through FiberPrinting also enables a smooth rotation profile, which eliminates cogging torque by forgoing the need for stator teeth. “Cogging torque and the associated iron losses are a notable source of energy losses at high rpm,” Nielsen said. “Even worse in that regard are the eddy currents, which occur as the rotor magnets move over the stator coils, as the iron takes extra energy [to break the excess magnetic attraction] and produces unwanted heat. By preventing those losses, our motors will therefore be much more efficient.” The permanent magnets in the company’s rotors are selected and integrated to maximise torque density and efficiency, and the motors themselves can be customised (configurable as inrunners or outrunners) to suit developers’ individual needs for speed, torque and physical volume. Unmanned Systems Technology | February/March 2020 Components of the Alva Industries radial flux motor