Airbus Zephyr

The Airbus Zephyr is a solar-powered High-Altitude Platform Station unmanned aerial vehicle originally designed by QinetiQ and built by Airbus Defence and Space since 2013. The current Zephyr S has a wingspan of about 25 m (82 ft) but weighs only 60-65 kg, carrying a payload of around 5 kg to a maximum altitude near 23,200 m (76,100 ft). Its power system is the defining feature: high-efficiency multi-junction gallium-arsenide photovoltaic cells generate power and recharge advanced lithium-ion batteries during daylight, which then sustain flight through the night — the central challenge of any Solar-Powered Aircraft (see Energy Density for why the night battery dominates the weight budget). The ultra-high-aspect ratio wing keeps the lift-to-drag ratio high enough that the modest solar power suffices. The Zephyr holds a series of endurance records. The earlier Zephyr 7 flew about 14 days in 2010; the Zephyr S managed nearly 26 days in 2018; and in a June-August 2022 flight it stayed aloft for 64 days and covered roughly 56,000 km before being lost. Intended uses include mobile-phone coverage (one aircraft is said to substitute for hundreds of cell towers), environmental monitoring, and military reconnaissance and communications relay. The programme has had several hull losses, including crashes in Australia (2019) and Arizona (2022).