A result of an intensive joint development effort between Sion Power and QinetiQ, the Zephyr flight exceeded 336 hours (14 days) of continuous flight, significantly surpassing the previous official record of 30 hours 24 minutes set by Northrop Grumman’s RQ-4A Global Hawk in March 2001. The Zephyr’s world record flight was completed on 23 July 2010 at the US Army’s Yuma Proving Grounds in Yuma, Arizona.
The Zephyr, a solar/battery powered all electric UAV with a wing span of 70 feet (22.5 m) and a weight of just over 110 lbs. (50 kg), achieved this record using a combination of solar power during the day and Sion Power’s Li-S batteries at night. After a ground launch, the Zephyr flew to altitudes of up to 70,000 feet, where the UAV encountered external temperatures as low as minus 75ºC.
The custom built Li-S battery pack was designed and assembled by Sion Power in Tucson, Arizona. The battery utilized Sion’s unique, high specific energy Li-S cells which provide 350 Wh/kg, the highest available for a rechargeable battery. The Li-S battery pack was carefully engineered to minimize total pack weight. Advanced electronic controls maintained the battery condition throughout the flight.
An official from the Federation Aeronautique Internationale (FAI), the world air sports federation, monitored the flight and is in the process of confirming a number of new world records. This includes quadrupling the Zephyr’s previous unofficial world record for longest duration unmanned flight, 82 hours, 37 minutes set in 2008. Zephyr will also have flown longer, non-stop and without refueling, than any other airplane—having significantly passed the Rutan Voyager milestone of 9 days (216 hours) 3 minutes and 44 seconds airborne, set in December 1986.