By MARK DAVIS
The Kansas City Star
KANSAS CITY, Kan. (AP) -- A team of Kansas City robotics enthusiasts kept a toy helicopter equipped with solar panels airborne for more than 24 hours this weekend by using a laser instead of the sun.
Brian Turner of the KC Space Pirates said their accomplishment doubled the previous record for laser-powered flight, The Kansas City Star (http://is.gd/7x39xN) reports.
More importantly, it showed that the concept works reliably.
Someday, laser-powered drones may serve as airborne cell towers or deliver refrigerated vaccines to remote locations. Lasers could recharge satellites' batteries or harvest solar power generated on satellites and deliver them to Earth.
The Space Pirates' laser-powered craft, however, was more like the Wright brothers' contraption than a Boeing 747.
"It started out life as a $300 toy called an AR Drone," he said. "We made some modifications."
They hung solar panels below the four-rotor copter. The panels absorbed energy from a 500-watt laser beamed at it from about 90 feet away and kept the copter's five-minute batteries charged all day.
The laser's beam was invisible, given that it was infrared light below the wavelengths the human eye can see. But it was many times more powerful than lasers that could harm a person's vision.
That's why, all weekend, someone always stood ready to hit the emergency stop button. And another team member was charged with making sure the stop-button sentry stayed awake.
"We're concerned about reflections," said Turner, sporting infrared-blocking eyewear over his glasses.
For example, the back of the solar panel beneath the copter was reflective. If the mechanical bird had unexpectedly turned around, it would have randomly scattered the powerful laser.
Luckily, that didn't happen. But plenty did on the way to the 24-hour flight.
Setup had begun early Friday evening inside the Vox Theatre in Kansas City, Kan. The copter floated about 7 feet in the air above a large white platform. An on-board camera and a computer program kept the vehicle stationary except for a slight swaying.
The invisible laser shot across the long hall, striking the solar panel and keeping the batteries charged and the vehicle aloft.
A second green laser also hit the panel so team members could see easily that the power-providing invisible light was on target.
An hour into the run, however, the laser slid off target, having been shaken loose on the way to the theater. The battery ran low and the copter touched down.
Two more hours of flight were wasted when air gusts from opening a door sent the drone off its target. It crashed into a nearby screen, and three of the 24 solar cells on the panel broke.
Repairs and adjustments took about half a day. The next flight lasted five hours until the team accidentally disrupted communications between the base computer and the copter. It touched down before anyone could grab the manual control, a Logi-tech game controller.
Finally, the record flight began Saturday afternoon, and the record fell around 4 a.m. Sunday. The team stayed another 13 hours to double the old mark.
The whole weekend was broadcast live online and recorded with time clocks running. Both were offered as evidence of the accomplishment, though, according to Turner, no organization officially recognized the achievement or that of the previous record holders.
"We just basically believe them," he said.
Information from: The Kansas City Star, http://www.kcstar.com