112 battery charge; for example, during take-off, landing and delivery. Independent tilting of the rotors makes the vehicles extremely responsive and agile, even in adverse wind. We are testing the limits of the overall system and would expect precision performance well above 25 kt gusting,” he adds. Mounting the motors on dedicated arms makes the dual configuration much simpler to achieve than it would be if Slate’s motors were mounted on the wings, he notes. The propulsion system draws about 750 W to 2500, depending on the payload and flight mode. LiPo batteries, then fuel cells Cobalt and Slate both use LiPo batteries, paired to enable hot swapping, so the UAVs do not need to be powered down. Customers can choose which brand of battery to use, but Blueflite prefers those of US firm Maxamps. “They make high-quality batteries, customise their systems to meet our requirements and we’re happy with them,” Noppel says. However, Blueflite is looking to increase the ability of future variants to carry worthwhile payloads over longer ranges with a fuel-cell system. Modular construction, along with plug-and-play interfaces, allows for easy replacement of parts in case of damage. “We track parts usage through our digital solution, so the operator knows when to change a certain part, and we also use artificial intelligence (AI) to predict failures before they can occur,” he says. Noppel says modularity allows more flexibility, as modifications such as adding an extra antenna or sensor are relatively simple, as are assembly and disassembly for transport and storage. Redundancy is an important part of Blueflite’s approach to reliability. With eight motors, the UAV can continue flying after several failures, even using the rotor tilt mechanism to compensate for resulting thrust asymmetry. The control system allows flight with one failed tilt mechanism and two failed propeller drives on that same arm. These mechanisms also enable the vehicle to operate in unusual attitudes, such as hovering noseup or nose-down. Both UAVs can be fitted with an emergency recovery parachute. Predictive maintenance enabled by AI software, and a non-conventional approach to the development of flightcontrol algorithms, centred on extensive use of simulation, are also key to Blueflite’s approach to design for reliability. Mean time between failures (MTBF) is a key measure of reliability. Blueflite has this data from suppliers and has performed analysis on their components to help determine the vehicles’ MTBF. “Each part on our drones is barcoded and registered in our digital cloud system for utilisation tracking, and the flight data is used for predictive maintenance,” Noppel says. Navigate and communicate Blueflite has engineered redundancy into its navigation and communication systems. Modern global navigation satellite system (GNSS) receivers routinely use signals from two or more navigation satellite constellations, such as GPS, Galileo, GLONASS and Beidou – Blueflight has integrated two receivers. February/March 2024 | Uncrewed Systems Technology Details of the motor mounting, tilt-arm quick-release mechanism and tilt actuators of the thrust vectoring system, pictured here on Cobalt. It is not a simple undercarriage With eight motors, the UAV can continue flying after several failures, even using the rotor tilt mechanism to compensate for thrust asymmetry
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