Unmanned Systems Technology 022 | XOcean XO-450 l Radar systems l Space vehicles insight l Small Robot l BMPower FCPS l Prismatic HALE UAV l InterDrone 2018 show report l UpVision l Navigation systems

76 Show report | InterDrone 2018 shaft forms part of the mount, and the stator and rotor are supported by two bearings each. The company also claims that the typical use of dual ‘back-to-back’ motor set-ups for coaxial rotors requires 30% more power than its patented configuration, while achieving equivalent thrust with identical input voltages. Electrafly unveiled a concept model for a quadcopter with several features and patent-pending designs aimed at enabling the transport of a human passenger or a payload of equivalent weight. As John Manning explained, “We use a hybrid-electric propulsion system, with four U15 II electric motors from T-Motor and a fuel thruster. Batteries still aren’t as energy-dense as fuel, so by replacing some of the battery weight with fuel, we increase the onboard energy density, which will give greater endurances and ranges. “We’ve also shaped the four motor arms like lifting airfoils, as it’s much more efficient to carry a load under a wing than lift it by a pillar of thrust. So, once in forward flight, they’ll ease the lifting burden on the electric motors.” A single turboprop engine (connected to a bladder fuel tank) is mounted beneath the hub of the craft, to assist take-off and cruise. The engine can use fuels such as diesel or Jet A. Future iterations of Electrafly’s craft are expected to integrate features including diesel generators and different power specifications for the engine and motors. To maintain stable flight with such alternative propulsion systems, the power output of the engine must be kept below that of the cumulative power output of the motors, and the motors must be positioned far enough from the engine and from each other to prevent having to counter the engine’s torque. Ballard Power Systems displayed its FCAir commercial hydrogen fuel cell products, developed for Group 1 and 2 VTOL, fixed-wing and hybrid UASs. They are said to provide a high-energy alternative to batteries for many UAS platforms, often achieving 2-3x the flight endurance for equivalent battery weight. “The FCAir line of products includes two fuel cell power plants, rated at 600 and 1200 W respectively; an array of lightweight, composite compressed hydrogen tanks; and a compact pressure regulator,” said Linda Mackay. “The fuel cell plant incorporates Ballard’s innovative liquid-cooled fuel cell technology that provides fast start-up time, and high durability and tolerance to a wide range of environmental conditions such as high altitudes and ambient temperatures.” The plants are equipped with control electronics to manage air, hydrogen and coolant flow within the system. They integrate power management electronics to enable full hybridisation with a rechargeable battery, such as 6S-8S lithium packs, to provide peaking capability. The system also includes a customisable heat exchanger to enable integration into a range of platforms. The FCAir 600h module weighs about 1.8 kg and produces 600-650 W continuous net power via the fuel cell only, or 1000 W maximum continuous net power when paired with a lithium battery. October/November 2018 | Unmanned Systems Technology One of the FCAir hydrogen fuel cells from Ballard Quadcopter concept model from Electrafly