The US Army's record-breaking Zephyr 8 uncrewed ultra-long endurance drone demonstration came to an abrupt end on August 18 at 9 pm PDT after an unprecedented 64 days in flight, when an unspecified and "unexpected" event brought the aircraft down over the Yuma Proving Ground (YPG) in Arizona.
Originally designed and built by British defense contractor QinetiQ in 2003 and now operated by Airbus Defence and Space, the Zephyr family of solar-powered soaring drones have been breaking endurance since 2008 when a Zephyr managed a 54-hour flight, which nearly doubled the then official world record time for the longest duration unmanned flight.
Zephyr 8, the latest version was built for the Army's Assured Positioning, Navigation and Timing/Space (APNT/Space) Cross-Functional Team (CFT) as part of an effort to develop a platform that can be used for long-term reconnaissance missions and to act as a high-altitude pseudo-satellite that can provide a communications hub equivalent to 25 cellphone towers.
Taking to the air on June 15 from the YPG, the Zephyr 8 was stationed in the stratosphere at an altitude of 60,000 ft (18,000 m) as it flew over the southern United States, the Gulf of Mexico, and South America, covering a distance of 30,000 nm (35,000 miles, 56,000 km). Its 64-day flight smashed all known uncrewed aircraft endurance records.
During the flight, the aircraft not only set a new endurance record, but also its first flight over water, flight in international airspace, first data collection and direct downlink while in international airspace, the longest continuous duration of seven days using satellite communications, and it demonstrated resilient satellite command and control from three different locations, including Huntsville, Alabama; Yuma, Arizona; and Farnborough, UK, as well as testing the drone's energy storage capacity, flight endurance, station-keeping, and agile positioning capabilities.
The Zephyr weighs less than 165 lb (75 kg) and has a wingspan of 82 ft (25 m). Its electric propulsion system is powered by 53 lb (24 kg) of lithium-ion batteries charged by the gallium-arsenide solar cells mounted on the upper wing surfaces.
According to the Army, no injuries were caused by the flight-ending incident and no other aircraft were endangered. An investigation into what happened is underway and more information will be released as it becomes available. Further flights have been put off until at least 2023.
"Our team is working hard to gather and analyze important data following the unexpected termination of this flight," said Michael Monteleone, Director of the APNT/Space CFT. "Despite this event, the Army and its partners have gleaned invaluable data and increased knowledge on the endurance, efficiency, and station keeping abilities of high-altitude UAS platforms. That knowledge will allow us to continue to advance requirements for reliable, modernized stratospheric capabilities to our Soldiers."
Source: US Army
