Prismatic and BAE Systems have completed the first successful test flight of the PHASA-35 High Altitude, Long Endurance UAV (HALE UAV) electric aircraft designed and built in the UK.
This first full scale flight trial took place at the Woomera test range in South Australia to look at the efficiency of flight, propulsion and power systems that can enable the aircraft to maintain flight at high altitude using minimum power from solar panels and a lithium ion battery pack. The aircraft is designed to fly for up to a year at an altitude of 18 to 23km (55,000 to 70,000 ft) with a payload such as a high resoluiton camera and radio link. The specification of the 15kg payload supports a power consumption of 300W to 1kW. The high performance battery pack is designed for 400 daily cycles to 90 percent capacity, which is over 146,000 cycles for a year-long mission, which compares to current1000 to 2000 cycle times for consumer lithium ion cells.
During the first flight of the PHASA-35 the aerodynamics, propulsion and power efficiency were all demonstrated to be exactly as expected, validating the system performance enabling persistent high altitude operation. Additionally, the aircraft was operated under full autonomous flight control, including precise landing in the face of significant side winds, demonstrating the fundamental robustness of the PHASA-35 design.
A quarter-scale version of the electric aircraft was tested in 2017.
The design by Farnborough-based Prismatic competes with the Zephyr HALE UAV from Airbus, which is also called a high altitude pseudosatellite (HAPS). The founders and management of Prismatic were all part of the Zephyr development at UK research agency QinetiQ. This also follows the Facebook Aquila HAPS system which was tested from 2016 to 2018 and developed by Ascenta in Somerset, UK. In 2018, Facebook said it was working with Airbus instead.