Unmanned Systems Technology 015 | Martin UAV V-Bat | William Sachiti | Sonar Systems | USVs | Desert Aircraft DA150 EFI | SeaCat AUV/ROV | Gimbals

10 Platform one Google is working on a way to overcome the limitations of fixed teleconferencing facilities by incorporating two-way video comms over a network into a small multicopter that can accompany a mobile user into restricted spaces in remote locations (writes Peter Donaldson). The idea is to enable a remote user to interact with colleagues in a larger fixed or mobile teleconference room. The multicopter would carry cameras, so that participants in the teleconference room can see both the remote operator and his or her surroundings, as well as a screen and audio output so that the operator can see and hear them. One version is based on a quadcopter with an airframe shaped like a capital ‘I’ with the rotors at the tips of the horizontals, seen from above. This airframe would support the lightweight screen, which can pivot underneath the UAV through a range of angles and swing up out of the way to reduce drag when it is moving between locations. The screen might even be perforated to allow air to pass through, further reducing weight and the holes being small enough not to affect image quality noticeably. The airframe would also support a projector to place images on the screen. Multicopter two-way video Communications August/September 2017 | Unmanned Systems Technology The second test flight of Facebook’s Aquila high-altitude UAV has provided some key data for aerodynamic modelling and design trade-offs (writes Nick Flaherty). The UAV flew for an hour and 46 minutes at speeds of 10-15 knots. It uses a dolly for take-off that is pulled along at 27 mph, and uses Kevlar pads under the four motors for landing, which caused problems in the first test flight. The designers have added spoilers to the wings to increase drag and reduce lift during the landing, and a new mechanism to stop the propellers when landing was also tested. The climb rate of 180 ft/min (0.9 m/s) was twice the rate of the first test, allowing the craft to reach its test altitude of 3000 ft (1000 m) quicker. The UAV is designed to fly at altitudes of more than 60,000 ft to provide wi-fi to an area with a radius of 60 miles (30 km). The team has also added hundreds of sensors, mostly strain gauges, MEMS accelerometers and three-axis inertial measurement units to gather new data about the movement and drag across the wings, which are 113 ft (34 m) long. In addition, the flight tested out modifications to the autopilot software for the new landing procedures, as well as a new radio subsystem with redundant uplinks and downlinks to increase the bandwidth. The Aquila flew test runs at a constant speed, heading and altitude to measure the drag from the new spoiler. This data will be used to refine the aerodynamic models that predict the energy usage and so optimise the size of the battery subsystem and solar array. Half the weight of 1000 lb (454 kg ) craft is for the lithium-ion batteries that are carried in the motor pods, implying a maximum power budget of 2.4 MWh from a battery energy density of 11.6 kWh/kg, or up to 104 kW. This will be needed to power the four motors during night-time operation and for broadcasting data to the ground. However, the additional weight of the wi-fi and comms equipment will mean fewer batteries can be carried so the power budget falls, creating a complex trade-off between the weight of the base station and the power consumption. A few seconds before landing, the autopilot stopped the propellers in order to lock them horizontally to prevent damage on touchdown. However, while all the motors stopped, only one propeller locked. The aircraft came to a stop in about 35 ft, marking its first successful landing without major damage. Aquila flies through test Airborne vehicles The latest Aquila UAV test flight trialled a range of modifications to the craft (Courtesy of Facebook)