The Zephyr was originally designed and built in 2003 by the BritishDefence contractor, QinetiQ. In a 2008 demonstration for the US military, a smaller-scale version of the Zephyr performed beyond the official world record for the longest-duration unmanned flight, however its 82-hour flight at an altitude of did not set an official record because FAI officials were not involved in the flight. The Zephyr 7 holds the official endurance record for an unrefuelled, unmanned aerial vehicle with its flight from 9 to 23 July 2010, lasting 336 hours, 22 minutes and 8 seconds. It could also remain airborne for months thanks to its solar cells and rechargeable batteries. Record claims have been verified by the Fédération Aéronautique Internationale for both duration and altitude, at 21,562 meters. It more than doubled the previous endurance record for unmanned flight. The Zephyr system was sold to EADS Astrium in March 2013 where it was successfully re-flown as part of the High Altitude Pseudo-Satellite programme. In 2014 it flew for 11 days in winter, and later near civilian airspace. In November 2015, in the House of Commons, British prime ministerDavid Cameron laid out plans during the Strategic Defence and Security Review 2015, to further enhance Great Britain'sintelligence, surveillance and reconnaissance capacity. In the speech, he stated that the UK was to field a 'British-designed unmanned aircraft that will fly at the edge of the earth's atmosphere and allow us to monitor our adversaries for weeks on end, providing critical intelligence for our armed forces." A purchase of two Zephyr-8's was reported in February 2016. In August 2016 Ministry of Defence confirmed the purchase of a third Zephyr 8 platform. In Summer 2018 for its maiden flight from Arizona, the Zephyr S remained aloft for 25 days 23h 57min, nearly twice as long as the previous record flight of 14 days set by its predecessor. It used Ampriuslithium-ion batteries with silicon nanowire anodes for a 435 Wh/kg specific energy up from 300-320 Wh/kg for conventional graphite anodes. In addition to Zephyr 8, otherwise known as Zephyr S, full-scale flight testing is scheduled for a twin-tailed Zephyr T variant in 2018 aimed at providing a maritime surveillance and communications capability.
Design
The Zephyr 6 is of carbon-fibre construction, and uses sunlight to charge a lithium-sulphur battery during the day, which powers the aircraft at night. The aircraft has been designed for use in observation and communications relay. The vehicle can circle over a particular area for extended periods with particular emphasis on its potential civil and military applications as an Earth observation and communications platform. During the day, Zephyr uses its solar cells spread across its wings to recharge high-power lithium-sulphur batteries and drive two propellers. At night, the energy stored in the batteries is sufficient to maintain Zephyr in the sky. The lithium sulphur batteries are supplied by Sion, and the first version had a battery capacity of 3 kW·h. Zephyr 7 was larger at 53 kg and capable of a maximum altitude between 65,000 and 70,000 feet, it required five ground crew to launch, as opposed to three previously for the Zephyr 6. The Zephyr 8 will have roughly 24 kg of batteries and a 5 kg payload, and be 30 percent lighter and carry 50 percent more batteries than the Zephyr 7. It has a 28-metre wingspan.
