If drones could eat other drones, the SparrowHawk would sit somewhere near the top of the flying-robot foodchain.
On a baking stretch of 110-degree dust an hour west of Phoenix, the six-rotored arachnoid rises with a menacing buzz, like a swarm of several dozen hornets' nests. Then the 14-pound, hexagonal drone lurches forward, towards its prey, a 3D Robotics quadcopter that its five-and-a-half-foot armspan dwarfs. The two drones perform a brief, mid-air dance before the SparrowHawk overtakes the quadcopter, and pulls it into a rectangular net that hangs beneath its body, tangling the smaller drone's rotors. The SparrowHawk then lowers to the ground, the captured quadcopter still twitching in its web.
On that scorching day earlier this month, the SparrowHawk was just one of several drone defenses tested by Phoenix-based security consultancy Bishop Fox. Fran Brown, a security researcher with the group, had invited WIRED to join the group for that day of testing, the results of which he plans to present at the Black Hat conference today. The comparisons weren't exactly scientific---think of it more as a group of grown men knocking expensive toys out of the sky. But Brown says the demos were designed to give Bishop Fox a sense of which drone-defense technologies to recommend to its customers. Those clients include multiple major film and television studios, which face drones that spy on secretive shoots. As those airborne spies spread, many customers find the sprawling array of anti-drone options–which range from lasers to falcons–a bewildering mess.
Many of those companies also overpromise, Brown says, advertising untested tools or even ones that won't be brought to market for years. "There are a ton of people trying to make a grab at this industry, and there's no practical guidance out there," says Brown. "This is all based on me wanting to know what to tell my customers about what they should be buying."
In Bishop Fox's testing, the company focused on just three of those options, all designed to be within reach for private sector customers, or even some consumers. (That meant skipping the multi-million-dollar directed energy weapons designed primarily for military budgets, radio-frequency jamming tools that potentially violate FCC regulations, or the drone-downing birds of prey that cost more than $150,000 to acquire and thousands more a year to care for.)
Here are the more practical drone defense tools they tested, and what they found.
Sky Net Shotgun Shells
Price: $20 for a pack of three. (Plus a $1,500 shotgun, though cheaper 12-gauge shotguns would work, too.)
These standard-sized shells contain compressed nets of thin mesh and metal weights, that catch on victim drones' rotors and other components to paralyze them mid-air. If Batman used a shotgun, he'd keep these in his utility belt.
The Bishop Fox team managed to down a stationary flying drone at about 70 feet within four or five shots. (The group had handed the shotgun to their most experience shooter. Your mileage may vary.) In most cases, the drone dropped immediately, its components damaged or wrapped in thin filaments. One shot somehow caused a DJI Phantom drone to veer off skyward; it eventually landed hundreds of feet away.
Aside from its unpredictability, the shotgun approach also poses a danger humans, though markedly less than actual shotgun pellets would. Brown warns that while a net might not seem like a serious weapon, the small metal pieces attached to it make it a potentially lethal projectile when fired out of a shotgun. (Another company promises a modified AR-15 that shoots drone-nabbing nets as well, though the ammo was not available at the time of testing.) The potential damage isn't limited to breaking off plastic drone cases, or sheering off parts. "If you got shot in the chest with this, you would die," says Brown. That means that while Sky Net shells are likely the most affordable option for most people, they're only practical in rural settings. "If there’s any chance of people downrange, you can’t use it."
Net Guns
Price: $500-$775
For those who'd rather not carry a loaded shotgun as their go-to drone defense, these smaller, flashlight-shaped "net guns" provide a less threatening approach. The two Bishop Fox bought for testing, a $775 model from NetGunStore.com and a $500 device from BigUrb, were originally advertised as animal control tools, and are far less dangerous than the Sky Net shells. But they also have a far shorter range, just 45 to 50 feet, according to the companies that sell them. That means careful pilots could easily keep their drones beyond the net guns' reach.
When Bishop Fox tested their net guns in the desert, however, they encountered another problem: The projectiles don't seem to function above a certain temperature. In Arizona's July heat, neither model would fire, perhaps due to the expansion of the canisters containing the pressurized CO2 that propels their nets. Even after cooling them under the air conditioners of their cars, Brown could only make one of the net guns lamely disgorge its net a few feet. In other words, look elsewhere for the solution to desert drone warfare.
The SparrowHawk
Price: Around $11,000
Finally, Brown pulled out what he described as his "pièce de résistance," the massive SparrowHawk drone-control system. The SparrowHawk is an adapted DJI Matrice 600, sold by the UK-based company SearchSystems with an added net more than six feet across, designed to drop from a pole hanging beneath the bot. The pilot console can control the drone itself, but also unfurl the net, rotate it, and even drop it with an attached parachute after ensnaring its target .
In Brown's testing of the SparrowHawk, setup proved difficult. He describes trying to assemble it from a manual filled with five pages of solid text and no pictures. When the Bishop Fox staff tried to launch it in the desert, they still couldn't figure out how to make its net automatically unfold, and two men had to attach the unspooled net from the ground as the giant drone hovered above them loudly.
Once it was airborne and deployed, however, Brown says the SparrowHawk was by far the most reliable method of drone takedown they tried, repeatedly chasing down and snagging its prey. And unlike the shotgun shells, it brought down the target drone without damage, so that it could be handed back to its owner unharmed, or forensically examined to find more signs of its purpose or who was flying it.
But all of that comes at a cost: Nearly $5,000 for the underlying DJI drone alone, and more than twice that for the full SparrowHawk system. SearchSystems' target customer is hardly your average backyard dronehunter; their marketing materials suggest it could be deployed from yachts to ward off any pesky spy drones that approach the ship.
And while the SparrowHawk bested the rest of the field, it has its own flaws. Aside from its clunky setup process and price, it's not clear if it could keep up with a more nimble or fast-moving target than the 3D Robotics quadcopter Bishop Fox tested it against. (Imagine the agility of racing drones applied to more malicious purposes.)
After his tests, Brown remains hesitant to point to any of the three products he tried as the best. He argues that the results show that each has its own application. The Sky Net shells might be the cheapest and most practical in an isolated setting, like the Arizona firemen whose helicopters and planes couldn't approach a forest fire in June because a hobbyist's drone hovered nearby. The short-range net guns might be most useful for celebrities or others trying to fend off paparazzi. (Hopefully in more temperate climates.) And the SparrowHawk could be used by corporations trying to keep spy drones away from their factories or movie sets.
Brown also notes that none of those solutions is perfect, and it may be years before those trying to control drones have the right tools on-hand at the right times. "It’s going to be an uphill battle for a while," Brown says. "You’ll see the evolution happen really quickly, but there’s going to be a lot of 'we were not prepared for this' across different industries."
The tools to fight flying bots are coming, in other words, or in some cases they're already here. But the drone wars are just getting started.
Additional reporting by Ryan Loughlin.
