Zephyr flies at Yuma Proving Ground—and beyond
Records are meant to be broken. When it comes to the Zephyr unmanned aircraft produced by
Airbus, U.S. Army Yuma Proving Ground (YPG) is the launching ground for longer flights into the next generation of aviation.
In 2010, the Zephyr unmanned aircraft stayed aloft for two straight weeks high above YPG, setting a world record. In 2018, an upgraded Zephyr returned to YPG and shattered its previous record, flying continuously for 25 days, 23 hours, and 57 minutes in YPG’s vast air space at altitudes far higher than normally achieved by commercial airplanes.
Today, the same aircraft used in
2018 is back at YPG, albeit with some differences.
“It has some design upgrades to make it a more capable system,” said Simon Taylor, head of Zephyr program. “The aircraft physically isn’t very different, it’s what sits inside the aircraft and the clever software inside it.”
Testers intended to double their previous feats by flying more than one aircraft simultaneously utilizing the same ground control station.
“We’re going for a much more ambitious flying campaign than we’ve ever attempted to date,” said Taylor. “Previously we’ve only ever successfully flown one aircraft in the flying window.”
Also new was the intention of flying the aircraft outside of YPG’s 2,000 miles of restricted airspace.
“They have an FAA certificate of authorization now to leave YPG restricted airspace and fly in national airspace,” said Lori Slaughter, YPG test officer. “They will leave our air space at altitude and stay at altitude in the national air space, above commercial aircraft.”
The construction of the Zephyr is minimalist. Constructed of composite carbon fiber, the craft weighs a feather-light 100 pounds and has no wheels or landing gear—it is launched off of the shoulders and from the hands of five running individuals. Virtually every square inch of the 80-foot wingspan is covered by lightweight solar cells that charge batteries that power twin electric motors. Also onboard are sophisticated electronics that allow the craft to be monitored and steered from a ground control station. All of this runs on the electrical power equivalent to that needed to light a single commercial light bulb.
“Unlike previous variants of Zephyr, this aircraft doesn’t need to drop out of the stratosphere overnight,” said Taylor. “This aircraft is capable of staying aloft above 60,000 feet, which means you are de-conflicting the weather masses below you, this leads to a very high mission probability of success.”
The Zephyr’s ability to fly at extremely high altitudes means it can safely evade bad weather while aloft. However, it is vital for the aircraft to perform its ascent and descent in favorable conditions. Part of the aircraft’s remarkable design involves coping with the stratosphere’s temperature, which is far colder than at ground level.
“The aircraft is effectively designed to operate in the stratosphere, so certain parts of the aircraft are shielded to keep temperatures under control,” said Taylor. “We also have thermal control on the equipment as well.”
The Zephyr crew labored at YPG since late last year utilizing test flight vehicles constructed at 30% scale of the actual Zephyr and an instrumented full-sized aircraft that flew 18 days over YPG collecting data prior to this summer’s attempt at another record. “We’ve done an awful lot of work proving out the design upgrades on the smaller-scale aircraft, building up to two aircraft operation,” said Taylor. “We have an immense amount of data from that flight test that will assist us with moving the design forward and informing the design of a future iteration of Zephyr.”
YPG averages 360 days of clear weather annually, and boasts stable air that is perfect for aircraft testing.
“The air mass here at Yuma Proving Ground is relatively stable compared to other parts of the world,” said Taylor. “What makes Yuma Proving Ground very attractive to us is the amount of weather data in the area and the relative isolation of its restricted airspace.”