A top secret class of autonomous drones is changing the way war is waged
By almost any account, the mission was a tremen­dous success, but an elemental part of the victory has gone all but unnoticed. The operation might never have happened were it not for a new aircraft, the Lockheed Martin RQ-170 Sentinel, which had been monitoring the location for months.
The aircraft’s mere presence over Pakistan was notable. Abbottabad is home to the country’s military academy and close to nuclear-weapons production sites and other sensitive facilities. The Pakistani government is especially vigilant about UAV activity nearby, whether it’s to deter Indian spies or unruly American allies. Suffice it to say, when Bin Laden was house hunting, “sheltered under an umbrella of radar protection” likely sat high on his wish list. Compared with neighboring Afghanistan, where Predator and Global Hawk reconnaissance craft roamed the skies, Abbottabad must have seemed a safe haven.
But Bin Laden never knew about the RQ-170. The top secret, remotely piloted aircraft, which arrived in Abbottabad as the search for the Al Qaeda leader intensified, was the first operational UAV able to conceal its own presence. The craft’s shape was designed to scatter radar waves, and other tactics helped mask its signature. It was considered only moderately stealthy, but it was still good enough to slip in and out of Pakistani airspace and capture video of Bin Laden pacing in his garden. That feat delivered more than a big break in a decade-long manhunt: It allowed a brief but revealing glimpse into the future of warfare.

NEW WARS, NEW CRAFTS

Since the September 11 attacks, the U.S. has been embroiled in a number of conflicts—directly in Iraq and Afghanistan, but also in shadow wars in Somalia and Yemen. Although each conflict is unique, all share a common and rather unusual characteristic: an asymmetric distribution of power, where one combatant has many more resources than another. In such situations, UAVs are ideal; they can be flown at will because the adversary has no means to shoot them down.
As military strategists look ahead, the days of asymmetric warfare and the uncontested airspace that comes with it seem to be drawing to a close. “There are no active area defenses run by insurgents in Afghanistan and Iraq or, for that matter, Syria,” says defense analyst Phil Finnegan, of the Fairfax, Virginia–based Teal Group. “But the next generation of UAVs will have to confront potential threats like China. They’ll need to be much more capable—faster, with greater autonomy in case communication links are disrupted, and stealthier so they are more difficult for an adversary to detect.”

The RQ-170 was the first evidence of such a program, but it was only the opening salvo. Engineers have already developed two new craft, Northrop Grumman’s RQ-180, now in tests at the military’s covert Area 51, and BAE Systems’ Taranis, which is geared more toward combat than surveillance. Both feature unprecedented levels of stealth for a UAV, and both are equipped with some form of autonomy, though the details remain a closely guarded secret.
As the pendulum of war swings back toward symmetrical conflicts, whether in Eastern Europe or the Pacific Rim, the designs of such craft are powerful indicators that military planners see UAVs serving a critical role. The challenge is to build them in such a way that they’ll function on their own without anybody ever knowing they’re there.

THE DISAPPEARING DRONE

At the height of the Cold War, Lockheed Martin developed the F-117 Nighthawk, the world’s first operational stealth airplane. To pilots, the gangly, heavily faceted, pitch-black aircraft appeared to abandon sound aerodynamics. The flat, radar-deflecting surfaces, they argued, would make the jet nearly impossible to fly. (They were right: It was safely piloted only with the aid of advanced, persistent fly-by-wire computer intervention.) Regardless, the design rendered it essentially invisible. On radar, the F-117 appeared no bigger than a duck.
As computing systems advanced, engineers could improve models’ stealth characteristics, and the Nighthawk’s awkward design fell by the wayside. Stealth airplanes, like the F-35 Lightning II fighter and the F-22 Raptor (the size of a marble on radar), began to more closely resemble conventional aircraft.
The RQ-180 and Taranis are perhaps the best examples of stealth applied to a UAV. Both use a flying-wing design also seen in the manned B-2 Spirit stealth bomber and the Navy’s X-47B UAV, currently in flight tests on aircraft carriers. Since there are no vertical stabilizers or bulky fuselage, radar reflects off fewer surfaces, masking the UAV’s signature. Of course, without those features the configuration is inherently unstable, so the craft have to adjust continuously via wing-mounted control surfaces.
In terms of stealth, the RQ-180, which first came to light in December 2013, has a distinct advantage: The wingspan stretches 130 feet. (RQ-170 has only a 65-foot span.) That width, plus finely tuned aerodynamics, not only lets the aircraft fly higher (60,000 feet) and longer than the RQ-170’s roughly six-hour limit, but it also allows engineers to place control surfaces farther out on the wing, where smaller adjustments are required to move the plane. This, in turn, means that the control surfaces can be much smaller, so they won’t catch radar.
The Taranis, on the other hand, has a modest 33-foot wingspan. That limits its range and altitude capability and requires larger stabilization panels (along with, presumably, a flight-control protocol to limit panel movement at certain stages of a mission). But it also makes the Taranis much more nimble than the RQ-180. The craft seems geared to low altitude and high speed.
Stealth is a game of give and take, and engineers are often forced to choose between performance and concealment.
In a recent paper published in The Aeronautical Journal, BAE Systems engineer Chris Lee described how the team developed an entirely new data-gathering-and- analysis system to hone the Taranis’s stealth characteristics during flight testing. The engine inlet and exhaust were given particularly careful attention. Shaping them to conceal the engine—which can quickly betray airplanes to radar—disrupts airflow, so engineers had to relentlessly tweak the engine design. Stealth is a game of give and take, and engineers are often forced to choose between performance and concealment.
The Taranis and the RQ-180 point to where UAVs are headed. Capable of flying more than 700 miles per hour, the Taranis has the speed and maneuverability to confront threats in combat head-on. The RQ-180 will pick up where the most famous spy plane, the SR-71 Blackbird, left off when it ceased operation in 1998. “The RQ-180 is a major step toward combining endurance and survivability in a high-end UAV,” says Loren Thompson, chief military analyst at the Lexington Institute. “In addition to performing reconnaissance missions, it will have some capacity to execute electronic attacks against enemy sensors and networks. I expect it will be used mainly in areas where the appearance of double-digit SAMs [surface-to-air missiles] and integrated air defenses have made the penetrability of nonstealthy airframes problematic.” Translation: It won’t get shot down.

PILOT-FREE WARFARE

In July 2013, the Navy’s X-47B approached the bucking, heaving deck of the USS George H.W. Bush aircraft carrier for a landing. Unlike remotely piloted drones, the X-47B had no human at the controls. Instead, it carried a sophisticated autonomous software package that guided it onto the flight deck entirely unassisted.
The X-47B’s demonstration simply confirmed what most aircraft engineers have known for a long time: Aircraft will become progressively more autonomous. Although it’s not stealthy, the Global Hawk UAV has significant autonomy—for years, it has navigated crowded airspaces and airports and flown in the same combat theaters as manned airplanes.
No one outside the military knows the exact nature of the autonomy packages of the RQ-180 and the Taranis, but they are almost assuredly the most sophisticated to date. Autonomy in aircraft is actually the “easiest” version of robotic self-control, since there are few obstacles in the open sky and considerable room to correct an error. (This is a sharp distinction from autonomous ground vehicles, which are years behind unmanned aircraft.) A suite of sensors, including radar, GPS, inertial navigation, and conventional autopilot functions, keep the airplanes in flight and in line with mission waypoints and goals, permitting them to collect data, send communications, and, in certain cases, drop bombs and launch missiles.
That said, it’s a fallacy to assume that robots will dominate all future combat. As many in the military see it, UAVs are force multipliers, not pilot replacements. “We’re never going to get to a point where we send robots out and they come back in 24 hours and we say, ‘Okay, tell me where you went and what happened to all those bombs you were carrying,’ ” says Lt. Gen. David Deptula, a retired deputy chief of staff for Intelligence, Surveillance, and Reconnaissance in the U.S. Air Force and the author of the Air Force’s road map for UAV integration. “The terminology is important. They’re part of a carefully executed system, not independent beings. Autonomous UAVs will be essential for supplementing weapons loads and amplifying sensor information available to human pilots in combat.”
The self-piloting systems, he adds, will also reportedly excel in routine missions and piloting tasks, allowing commanders to more strategically use the human pilots they do have. “Given that we have less than half of the F-22 fighters that we asked for, we need to boost our numbers,” Deptula says. They’ll also be able to operate independently should communications be disrupted—or deliberately jammed—which would put a remote-piloted vehicle in jeopardy.
When facing opponents with the technology to inter­fere with enemy systems and a multitude of ground- and air-based defenses, the advantages of having these options stack up.

XPlane Simulation. Austin Meyer/Xplane

THE BATTLE AHEAD

Even with the many advantages that UAVs pose, the relationship between man and machine on the battlefield will remain complex for the foreseeable future. And within the Armed Forces, there are a number of competing visions for how the relationship should unfold. “There are people in the Pentagon who have the right idea about where we have to go in the future, on a practical level,” says Mary Cummings, a former U.S. Navy fighter pilot and systems engineer who now directs the Humans and Auto­mation Laboratory at Duke University. “But there are also still people, even within the Air Force, who have a visceral response to UAVs, and they keep trying to gut the program.”
Of all the armed services, the U.S. Army seems the most amenable to using UAVs. “Perhaps surprisingly, they’re the farthest ahead of all of the services in terms of integrating unmanned aircraft,” says military analyst Paul Scharre, a fellow at the Center for a New American Security. “The Army has adopted a concept of manned-unmanned teaming—pairing unmanned aircraft with manned helicopters. It wants to eventually include cooperative multi-aircraft control where one person controls several aircraft at the same time, operating as a ‘swarm’ in surveillance, communications relay, cargo resupply, and close air support missions.”
“The number-one thing we need next is flawless communication—a robust, reliable, secure means of exchanging information."
As military technicians start mocking up battlefield plans for future wars, sophisticated tactics like these will likely be necessary to gain an advantage. They may even be essential to victory. But the vision of a unified, cooperative man-and-machine strike force is still missing a crucial component. “All the sensor technology is moving quite nicely into the future. Stealth, autonomy, and aerodynamics are also maturing rapidly,” says Deptula. “The number-one thing we need next is flawless communication—a robust, reliable, secure means of exchanging information. That is the linchpin for developing what I call a ‘combat cloud’ for our campaigns. That’s our next great challenge.”
By Eric Adams. This article originally appeared in the January 2015 issue of Popular Science.


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