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Platform one A HALE unmanned electric aircraft developed by Prismatic in the UK has been tested in Australia at altitude (writes Nick Flaherty). The first full-scale flight trial of the PHASA-35 took place at the Woomera test range in South Australia, and looked at the efficiency of flight, propulsion and power systems. The aircraft, also called a high altitude pseudo-satellite, is designed to fly autonomously for up to a year at an altitude of 18 to 23 km (55,000-70,000 ft) using lightweight gallium arsenide solar panels and a lithium-ion battery pack. It uses two brushless direct-drive electric motors and custom-designed propellers to provide a top speed of 78 knots. The design supports a 15 kg payload such as a high-resolution camera with a power consumption of 300 W to 1 kW. Data from aircraft links to the ground via Iridium’s short data burst satellite service provides control at a range of up to 400 km. The battery pack is designed for 400 daily cycles to 90% capacity, which is more than 146,000 cycles for a year-long mission. That compares to current 1000-2000 cycle times for consumer lithium-ion cells.  During the PHASA-35’s flight its aerodynamics, propulsion and power efficiency were all demonstrated to be exactly as expected, validating the system’s performance for high-altitude operation. HALE UAV hits the heights Airborne vehicles The PHASA-35 has a top speed of 78 knots and can reach altitudes of 18-23 km