Unmanned Systems Technology 012 | AutoNaut USV | Connectors | Unmanned Ground Vehicles | Cobra Aero A33i | Intel Falcon 8+ UAV | Propellers | CES Show report

68 P ropellers have long been key to the operation of airborne and sea-going craft. Although newer technologies such as hydrojets in the water, and jet engines in the air, have their place in high-speed systems, nearly all manned and unmanned vehicles are subsonic, and thus continue to use propellers for generating propulsion. USVs, UUVs and large MALE-class UAVs can draw on decades of propeller development for similarly sized vehicles, which bridges the manned-unmanned divide with few adjustments. Small UASs meanwhile often take existing propellers from the hobbyist radio control realm, granting a wide choice at low cost to UAV manufacturers. However, researchers investigating the qualities of such propellers have found that they are poorly suited to small UAS flight, having been designed for imitative purposes, with physical dimensions more closely resembling those of propellers designed for horizontally flying manned fixed-wing aircraft, making them inadequate for the efficient generation of propulsion on small UAVs, and particularly so for take-off and loitering in rotor-wing systems. Aircraft propellers are expected to reach around 80% efficiency when Rory Jackson examines the latest developments in propeller configurations, including new blade designs and trends in materials Rotary in motion The General Atomics Predator-B operates a hydraulically actuated variable-pitch propeller with three aluminium blades from McCauley Propeller Systems (Courtesy of US Air Force) February/March 2017 | Unmanned Systems Technology