It took Chuck Pell less than a minute to build his drone.
He folded a piece of paper 11 times, clipped on a battery-powered plastic propeller and rudder, then opened an app on his iPhone.
Next he flung the aircraft skyward, steering it above the trees with turns of his phone. The plane soared out of sight.
It's a good technology, according to Mr Pell, who has suffered plenty of nose dives. It just "needs more pilot training".
Aerial drones have fought in wars, filmed movies and factored into the ambitious plans of high-tech executives who want to supply internet service from the air.
Now there is a new but familiar shape to the fast-growing world of unmanned aircraft: the paper aeroplane.
The PowerUp 3.0, brainchild of former Israeli Air Force pilot Shai Goitein, is a lightweight guidance-and-propulsion system powered by a dime-sized battery (slightly smaller than an Australian $2 coin). It clips onto origami aircraft and connects to iPhones using Bluetooth, transforming them into remote-control drones.
Pocket-sized drones like the PowerUp aren't as sophisticated as the devices Jeff Bezos says could one day deliver packages for Amazon.com, or the big solar-powered models being engineered by companies that Google and Facebook recently acquired.
But enthusiasts are embracing these minidrones as a cheap, souped-up way to get high.
In less than a year, Estes-Cox Corp -- a Colorado maker of model rockets -- has sold more than 500,000 versions of its remote-controlled nanodrone, which is 1.8 inches (4.6 centimetres) square and retails for $US40. French company Parrot SA, one of the largest drone makers, is launching a minidrone with detachable wheels that allow it to land and immediately start driving -- even up walls.
Harvard University researchers have developed a still tinier drone, the RoboBee, which has insect-like wings that span the diameter of a half-dollar (US). The whole machine weighs less than a third of a penny.
The researchers say the potential uses of tiny drones range from pollinating crops to military surveillance to traffic monitoring.
The next step
Goitein says he and a rocket scientist friend came up with the idea for PowerUp in 2006. After developing an unpiloted version, Mr Goitein went on crowdsourcing website Kickstarter in November last year seeking $US50,000 to make a remote-controlled edition. He got that in eight hours. Two months later the total was $US1.23 million. The first 50 kits went to beta testers like Mr Pell in February. It costs $US50.
With the extra funds, Mr Goitein is adding a dogfight mode that lets one pilot shoot down an enemy paper plane with a Bluetooth signal that stops the rival's engine. The next-generation PowerUp will have a magnetometer, accelerometer and gyrometer, he said. Eventually, he said, "It'll definitely be a real drone".
Users are adding their own innovations. Andre Bowen, an artist in Berlin, says he plans to 3D-print some aeroplane models to make them fly with the PowerUp. Zachary Read, a high school junior from Flower Mound, Texas, is working on a PowerUp flying saucer, stealth bomber and F-16 fighter.
Here in Durham, about 180 miles west of where the Wright brothers made their first flight in Kitty Hawk, N.C., Pell carried two boxes of planes folded from paper, parchment and papyrus -- "pounded reed, not that cheap stuff," he said.
Pell, a scientist and inventor who started his career building animatronic dinosaurs for museums, has found that flying paper planes still involves a lot of failure. Most of Pell's planes nose-dived. A few flew loops until crashing. Only a handful stayed aloft longer than a well-made, unpowered paper plane, including the one that glided out of sight.
"That's the beauty of paper planes," Pell said. "Lots of quick, cheap failures are a desirable thing … I don't learn much when it succeeds; I learn a lot when it crashes."
In 1998, US Air Force aeronautical engineer Ken Blackburn tossed an unpowered paper plane in Atlanta's Georgia Dome that flew for 27.6 seconds, a Guinness World Record that went unsurpassed until a Japanese origami expert broke it by 0.3 second in 2009. Recently, a Swiss man posted videos of himself flying his PowerUp paper plane for several minutes.
Chuck Pell holds a paper plane outfitted with a PowerUp engine. Jack Nicas/The Wall Street Journal.
Does that count? "I wouldn't doubt there are a few purists out here who tend to ignore it because it's not a real paper airplane," Blackburn said.
More than just a toy?
Current court cases, however, are wading into debates over whether a powered paper plane could legally be a real aircraft.
The US Federal Aviation Administration for years allowed the model aircraft industry to largely regulate itself, relying on voluntary guidelines issued in 1981 that urged model pilots to fly below 400 feet and stay away from airports and densely-populated areas. But in recent years, in reaction to the surge in US drone use, the FAA has staked out greater authority to regulate unmanned aircraft.
The agency says it regulates "the airspace from the ground up", and that all flying devices are subject to its regulation. In March, a National Transportation Safety Board judge overturned a $US10,000 FAA fine levied against a man for allegedly flying a drone recklessly, saying "model aircraft" aren't subject to the FAA's rules regarding manned aircraft. If the FAA's argument that all types of flying devices are aircraft, the administrative judge wrote in his opinion, then the agency should also regulate "paper aircraft, or a toy balsa wood glider".
In an email statement, the FAA said the PowerUp is a toy and that users should "fly safe and have fun".
Pell, who is also a competitive boomerang thrower, expounds on the aerodynamics that makes each of his paper planes fly. He has given talks to college students on the first 400,000 years of humans and aviation, ending with the Wright brothers, touching on everything from the 'kylie', an Australian-aboriginal hunting stick, to kites to the bow and arrow.
All aviation pioneers began with models, and paper planes especially "are the sandbox of aviation", he said. "With no money or time, you can try all those crazy designs and get them to work."
Blackburn, who has written four books on paper planes, said he's excited about the PowerUp because it solves a longtime problem.
"I was always looking for ways to add propulsion," he said. As a child, he taped bottle rockets to his paper planes. "Not that I encourage kids to do that -- though the explosion at the end is kind of spectacular."
Write to Jack Nicas at firstname.lastname@example.org