Zephyr, a solar-powered unmanned aerial vehicle (UAV), attracted attention for the two-week duration of its test flight when it touched down in Arizona in July. The aircraft was, in fact, developed for high-altitude, long-endurance (HALE) flight by British defense technology company Qinetiq, which believes its mission capabilities and relative low cost will reshape the logistics of UAV operations.
Jon Saltmarsh, the project manager, said “The concept of Zephyr was to produce an aircraft that stays in the air for three months,” adding “When you start believing that’s possible, you start thinking about what it means [for operations].” Qinetiq estimates that Zephyr is a year away from a 3-month continuous flight.
Saltmarsh explained “There are things meeting this [need] at the moment called satellites.” But, unlike a satellite, Zephyr can be launched with minimal notice and little expense, it can be easily re-tasked once operating and, if a fault develops with the payload, quickly recovered, repaired and re-launched.
There are other differences between Zephyr, which stores solar energy in lithium sulphur batteries, and conventional UAVs. Along with removing fuel from the operational equation, eliminating the need to land frequently changes the approach to operations.
Zephyr operates on autopilot, flying remotely reprogrammable routes between selected way points, where no human operator would be needed. During test flights at Yuma Proving Ground, Arizona, Qinetiq used a pilot during takeoff and landing but believes there is no need for a human in the loop for either operation. During the test flight, the pilot controlled the UAV to 10,000 ft., above which the autopilot was engaged, and took control again when it descended to that altitude. Zephyr is designed to fly at 70,000 ft.
The propeller-driven aircraft has no undercarriage and is hand-launched by a team of three or four people, who run 20 meters (65 ft.) to get it airborne. Although conceived of as disposable, Qinetiq found that Zephyr’s carbon composite structure was strong enough to withstand the impact of landing, so the airframe is reusable.
Zephyr weighs 30 kg. (66 lb.) and has an 18-meter wingspan. It is weather-sensitive and must be launched with as little wind as possible, preferably at dawn to maximize the time its solar cells gather power before nightfall. Saltmarsh argues that this is not so much a problem as a reason to think differently about operations. “If you’re going to have a launch site remote from the area of operation, you would pick somewhere that usually has good weather,” said Saltmarsh.
Qinetiq has not set a price but claims that through-life costs will be around 1% of a satellite and 10% of a conventional UAV. It would thus be economical to equip multiple Zephyr airframes with different sensors and do surveillance mission individually.
On its two-week flight, funded by the U.K. Defense Ministry, Zephyr carried a classified military communications payload made by Qinetiq. In other test flights, the aircraft has carried cameras and communication relays. Qinetiq sees the ability to provide a means of relaying high-bandwidth applications such as full-motion video (at Yuma, Zephyr flew with a 100-Mbps. data link) as a major benefit. Potential civil applications include atmospheric and environmental data collection, mapping and photography, communication relays in disaster zones and wildfire monitoring.