Drone Aircraft: How the Drones Got Their Stingers

Unmanned aerial vehicles come of age

This is part of IEEE Spectrum's special report: Top 11 Technologies of the Decade

Cruising silently overhead, an unmanned Predator aircraft uses its infrared camera to pinpoint the telltale muzzle flashes from a sniper's rifle. The plane's operators, located half a world away, then unleash a Hellfire missile from under its wing, using a laser mounted beneath the craft's nose to guide the munition into the very window the sniper had been shooting from.

Such missions represent a technological tour de force, but they've played out so often over the past few years that they no longer make headlines. What might be news, though, is just how far back the roots of this stunning 21st-century military technology reach.

The first demonstration of a remotely piloted vehicle took place in May 1898 at the Electrical Exposition in New York City's Madison Square Garden. It was less than a month after the outbreak of the Spanish-American War, which, as history buffs may recall, was sparked by the mysterious explosion and sinking of the U.S.S. Maine in Havana harbor. So when the renowned inventor Nikola Tesla used the exposition to demonstrate his "telautomaton"—a small boat operated remotely by radio—the military significance of his creation must have been obvious.

Or maybe not. Perhaps no one watching Tesla steer and flash the lights of his robotic boat had sufficient imagination to see how valuable pilotless vehicles could be in war. Yet that very year Tesla sent a paper to The Electrical Engineer magazine describing how a remotely controlled aircraft could be used as an aerial torpedo. His submission was rejected as too fanciful.

Attitudes, of course, evolved during the 20th century. As early as 1917, the U.S. Navy pursued the development of a pilotless aircraft for use against German U-boats; during the Second World War, Nazi forces filled the skies over Britain with thousands of pulse-jet-powered flying bombs; and Israeli Defense Forces used drones against Syrian forces in Lebanon in 1982. But it was only during the past decade that unmanned aerial vehicles matured into fully controllable and reusable combat aircraft. They have also proliferated, often in miniaturized forms, providing easily deployed eyes in the sky for ground troops.

The relatively late blossoming of these vehicles can be explained, in part, by improvements in the various technologies they rely on. But an increased understanding of their utility on the battlefield also accounts for the recent upsurge in their use.

Pilotless aircraft began as preprogrammed drones, evolved into remotely piloted vehicles or unmanned aerial vehicles (UAVs), and are now sometimes called unmanned aircraft systems (UASs), in appreciation of the aircraft's role within a larger collection of complex equipment.

They're most commonly used for reconnaissance or sustained surveillance. But many UAVs are equipped with lasers that can illuminate a target or even mark it for automatic destruction, using laser-guided weapons launched from other platforms. And some of the larger UAVs carry missiles themselves. At the small end of the spectrum are UAVs that a single soldier can carry around and launch by hand. AeroVironment, a company headquartered in Monrovia, Calif., manufactures some of the better-known examples, including the Raven, which is fundamentally similar to the radio-controlled planes that hobbyists fly for fun, although it's much tougher and packs more sophisticated electronic gear.

So, clearly, the wherewithal to construct a small UAV has been around for a long time. Why then has the use of Ravens and other hand-launched UAVs burgeoned only in the last decade?

"The technology definitely matured," says Gabriel Torres, an aeronautical engineer and project manager at AeroVironment. He notes that the Pointer, the 1990s-era predecessor of the Raven, used nickel-cadmium batteries and could remain aloft for only 30 minutes, one-third as long as the lithium ion–powered Raven can. The Pointer's support equipment was also awkwardly bulky for a soldier to carry around. "The ground-control station was like an 80-pound box," says Torres. The craft was also limited by its rudimentary autopilot, which initially relied on an electromechanical compass. "But little by little, the technology improved," says Torres.

Strides in the fabrication of microelectromechanical systems, for example, allowed tiny gyroscopes, accelerometers, and airspeed sensors to be added to the smallest of these vehicles, along with increasingly compact and reliable GPS receivers. "The other thing that changed," says Torres, "was an appreciation of the kind of mission that could be fulfilled with this type of system." With the Raven, he explains, U.S. military planners were able to work out detailed tactics, techniques, and procedures for soldiers to use small aerial vehicles in combat. "This all became very important in 2000 and 2001," he says.

This period was also a turning point for larger UAVs, in part because of advances in computers and radio links. The more important reason to call 2001 a watershed year, however, is that it marked the very first time anyone put weapons on a reusable unmanned aircraft.

Prioria Robotics,
Gainesville, Fla.

Prioria Robotics is building small UAVs that autonomously use video to steer around objects. The ability of UAVs to sense and avoid other aircraft is a prerequisite for flying in civilian airspace, and small smart vehicles, like the ones Prioria is developing, may be the first to do so.


On 2 August 2010, one of the U.S. Navy's unmanned Fire Scout helicopters lost communication with operators and was fast approaching Washington, D.C., before it was brought under control.

When General Atomics Aeronautical Systems developed the Predator in the mid-1990s, it was intended solely for surveillance. Plans took a sharp turn, though, during one of its early military deployments, with NATO forces over Kosovo.

That's when Gen. John P. Jumper, commander of U.S. Air Forces in Europe, noticed what he called "the dialogue of the deaf." Predator operators would identify a target, say, an enemy tank lurking between buildings, and then try to guide the pilot of an attack aircraft to it by radioing verbal instructions. More often than not, this just caused a lot of confusion.

So Jumper had the Predators outfitted with laser designators, which could automatically guide missiles or artillery shells to their targets. He later pushed for the Predator to carry its own weapons, and the first instances of this UAV using air-to-surface missiles took place not long after, in the hunt for al-Qaeda members in Afghanistan in October 2001.

The following year saw the Predator's role expand to ground support, when it destroyed a machine gun bunker that had pinned down U.S. Army rangers in Afghanistan. And for the first time, a Predator fired a Stinger air-to-air missile in action, at an Iraqi fighter.

That same year technical refinements allowed operation of a Predator to be shifted from one ground control station to another, so that UAV pilots located in combat areas could pass control to comrades stationed at U.S. bases. This is how the U.S. Air Force operates its UAVs, using pilots and crews deployed overseas to launch and recover the aircraft, while pilots at Creech Air Force Base in Nevada manage the intervening part of the missions.

This approach is decidedly different from the way the U.S. Army handles its fleet of more than 4000 UAVs, including the biggest one it flies, known as the Gray Eagle, which can carry four Hellfire missiles and looks something like a Predator on steroids.

For one, all Army UAS operators work alongside combat troops, even for vehicles that are capable of being flown over satellite links from anywhere on the globe. Also, unlike the Air Force, the Army hasn't restricted itself to using officers with piloting experience to operate its UAVs.

The Air Force initially put just seasoned aviators in that role, although it has more recently started using men and women who have spent only a few tens of hours in the cockpit—about what it would take to get a private pilot's license—to fly its UAVs. The Army, however, trains people who have never flown regular aircraft for that job.

"We recruit folks coming out of high school," says Lt. Col. Patrick Sullivan, commander of the Army's unmanned aircraft systems training battalion, located at Fort Huachuca in southeast Arizona. "We have soldiers that just came from basic training. They come to Fort Huachuca, and we train them to be UAS operators."

Army Col. Robert Sova, training and doctrine command capability manager for UAS, confirms that this approach extends throughout the Army. "Everything from our smallest systems to our largest are flown by enlisted operators," says Sova. "They don't have a pilot's license—they are not pilots. That's why we're adamant about calling them 'operators.' We have no intention of having pilots flying our unmanned aircraft."

The Army's stance on this point reflects that service's particular history and culture. But it also reflects the evolution of UAS technology. During the 1980s and 1990s, operating such an aircraft indeed required someone with considerable training and good eye-muscle coordination. It might even require two of them. The "external pilot" would handle the takeoff and landing by looking directly at the plane, while the "internal pilot" would manage operations for the bulk of the flight.

Steve Reid is vice president of unmanned aircraft systems at AAI Corp., the Hunt Valley, Md., company that makes the Shadow, a 3.4-meter-long UAV that the U.S. Army adopted for tactical use in late 1999. He explains that in 2001 and 2002, AAI added special radio equipment to allow the Shadow to make automated landings. Although engineering such capability was a considerable challenge, it relieved the Army of having to train pilots in the tricky skills needed to land these planes by eye. What's more, the automation works better. "I can tell you great stories of sandstorms rolling into Iraq—blinding sandstorms, where you can't see any aircraft out there—and Shadows land right where they are supposed to," says Reid.

Army Sgt. 1st Class Kelly Boehning, a Gray Eagle operator stationed at Fort Huachuca, has similar praise for his craft's automated landing system. "It lands perfectly, every time, without exception," says Boehning. "It takes some of the fun out, not having the stick and rudder, but it also takes the pilot error out: We don't have any incidents landing—that's where Predator's downfall is."

Automation is indeed a strong theme in the Army's recently published Unmanned Aircraft Systems Roadmap for the next quarter century, a document that discusses such advanced possibilities as UAVs delivering cargo to soldiers on the battlefield or flying UAV missions in coordinated swarms.

Military UAVs still have a poor safety record compared with piloted aircraft, but as trust in them mounts, there's little doubt that their use will expand and spill over into civilian applications. "There's a hunger out there in the commercial sector for this type of technology—for use in everything from UPS and FedEx flights, pipeline surveys, forestry, logging, law enforcement—just about anything you can think of that uses aircraft today could benefit from a low-cost, reliable, and safe unmanned aircraft technology," says retired Army Lt. Col. Glenn Rizzi, senior advisor to Col. Sova.

It will, of course, be a long while yet before the typical traveler will be comfortable taking an airliner with no pilot on board. But well before that, we're likely to see UAVs of other varieties flying in civilian airspace.

Understandably, aviation authorities need to police developments here cautiously so that the safety of air travel isn't compromised. But the steady advance of communication and automation technology—which is already quite sophisticated in today's airliners—will surely open the skies to pilotless aircraft of many types. As Rizzi contends, "The future [of UAVs] is only up."

This article originally appeared in print as "How the Drones Got Their Stingers".

About the Authors

For more about the authors, see the Back Story, "Flybot for a Day."

For all of IEEE Spectrum's Top 11 Technologies of the Decade, visit the special report.

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