One of the biggest drones ever built will not kill you. In fact, the manufacturers of the Phantom Eye are thinking about the massive, hydrogen-powered flying robot as a communications relay station.

The Phantom Eye is a beast: wingspans of 150 feet; a gross takeoff weight of 10,000 pounds; room for up to a 450 pound payload; two four-cylinder engines each providing about 150 horsepower. It runs on liquid hydrogen, not only making it greener than the rest of the U.S. military's drone fleet, but, Boeing believes, three times more energy-efficient. Most drones are lucky if they can stay aloft for a day at a stretch. The Phantom Eye aims to stay in the air for up to five days, and about three times higher – at 60,000 feet.

Nearly three years after Boeing unveiled it, the Phantom Eye hasn't exactly gone according to plan. Its first test flight, last June from California's Edwards Air Force Base, led to a broken nose landing gear, something Boeing's Keith Monteith says helped keep the drone out of the public eye. The Missile Defense Agency last year tried and failed to arm the Phantom Eye with a huge laser cannon. Its second fight test, also from Edwards, reached altitudes only as high as 8,000 feet, and lasted only an hour and six minutes.

If that wasn't enough, defense budget cuts make 2013 not a particularly auspicious time to sell the military on a ginormous new drone. Yet there Monteith was today, manning Boeing's booth at the Navy's annual Sea Air Space Convention, a white plastic model of the bulbous Phantom Eye on display. "We're trying to generate customer interest," he said, diplomatically.

So Monteith, the manager of business development for advanced strategic systems at Boeing's Phantom Works division, is coming up with unconventional pitches for the Phantom Eye, in the hopes they'll appeal to a cash-strapped Navy.

Sure, the drone's enormous cargo room and long endurance capabilities make it capable of hauling more and increasingly powerful camera packages. But persistent surveillance is a crowded market, particularly for a Navy in love with its Broad Area Maritime Surveillance drone and forthcoming spy-n-kill 'bot launched from an aircraft carrier. So Monteith figures the Phantom Eye also has value as a communications relay hub.

"It could support communications for a carrier battle group without taking up space on a flight deck," Monteith says. One day, a Phantom Eye takes off from the U.S., carrying communications relay equipment, and settles over a battle group in the Indian Ocean, he suggests. It settles in, way, way far out of sight, for three days; on the fourth, a replacement arrives. "We could do it continuously," Monteith says.

It remains to be seen if the Navy can be sold on that use of a brand-new drone. But increasing and supplementing ship-to-ship communications at greater distances is a priority: it's rolled out a 4G wireless network on an amphibious assault ship. It might not be what Boeing initially anticipated, but it might be the best deal the aerospace giant can get. And a third flight test will occur "very soon," Monteith says.