U.S. Army's Zephyr S, solar-powered, very-high-altitude, Drone made a Record Flight.

 



Airbus' Zephyr S solar-powered, very-high-altitude unmanned aircraft is in the midst of a long-duration test flight and has already been aloft for 17 days so far. The drone, sometimes described as a pseudo-satellite in terms of potential capabilities, took off from the U.S. Army's Yuma Proving Ground in Arizona last month for what the service says is a test of its highly efficient long-endurance flight characteristics as part of broader work to demonstrate its ability to serve as a persistent sensor platform.

"This experiment is intended to test the UAV's energy storage capacity, battery longevity, solar panel efficiency, and station-keeping abilities."

The Zephyr S's design is optimized for highly efficient high altitude flight. It has an 82-foot wingspan, but a small central fuselage containing its avionics and data-links. Its total weight is just 165 pounds, light enough to be literally hand-launched by a small team of people holding it over their heads while running it down the runway. It can fly up to 76,100 feet. 

When the Zephyr S first flew in 2018, the drone remained airborne for nearly 26 days. This stands to this day as the world record for the longest duration flight by an unmanned aircraft of any kind. That flight was enabled in part by improvements to the design that ensured that it could remain at very high altitudes the entire time. Older Zephyrs had to dip down to lower altitudes during multi-day flights.

"Unlike previous flights when the aircraft had to come down to between 25,000 and 35,000 feet at night, but this time we were able to stay above the weather," Lori Slaughter, a test officer, explained. "Our lowest altitude during the flight itself was 55,000 feet."

This capability also means that the drone can evade pretty much all bad weather, further improving its mission performance and ability to stay on scene for very long periods.



For comparison, the longest flight, at least that we know about, ever completed by a Northrop Grumman RQ-4 Global Hawk unmanned aircraft, lasted just over 34 hours. The RQ-4 has a service ceiling of 60,000 feet, thousands of feet below that of the Zephyr S.

Zephyr was originally developed by U.K. defense contractor QinetiQ, which then sold the design to Airbus in 2013. The U.S. military, including both the Army and the Navy, have been experimenting with various Zephyr models since the late 2000s.

There are various other potential uses of Zephyr beyond carrying sensors, too. The performance capabilities of these drones would be equally useful when acting as nodes supporting navigation and communications and data-sharing networks.

The ability of Zephyr drones to augment or even replace satellite-based systems as necessary could be valuable in post-disaster scenarios, especially where traditional internet networks are rendered inoperable.

The possibility of utilizing Zephyr-series drones for persistent surveillance or networking support over open-ocean and littoral areas has long been one particular area of interest for the U.S. military.


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