UAV updateLaser-powered, ground-charged UAV stays aloft for hours
A UAV is only as good as its power source: if the drone cannot stay over target for long periods of time and must return to base to refuel, this not only adds to the costs of operating the drone but it also degrade its intelligence gathering capabilities; Seattle-based company demonstrates that it can use a laser beam to charge the UAV’s photovoltaic cells, generating enough power to keep the drone in the air for hours; the company has bigger plans for extending flight duration of military craft — and much more: in the longer term, it envisions lasers powering remote ground-based sensors, delivering power to forward military bases, or supplying emergency power during disasters
Laser refueling could allow indefinite flight time // Source: defpro.com
A UAV is only as good as its power source: if the drone cannot stay over target for long periods of time and must return to base to refuel, this not only adds to the costs of operating the drone but it also degrade its intelligence gathering capabilities.
The search for better sources of UAV power is intense, and many technologies are being considered that could dramatically extend the duration of drone missions. DARPA’s Vulture program, for example, has helped develop a giant solar plane that, theoretically, could fly for five years straight.
Seattle-based LaserMotive thinks laser power is the answer, and to prove it they recently kept a tiny 22-gram helicopter aloft for hours.
This is interesting, because lasers have recently shown they can down an unmanned aerial vehicle (UAV) — and the LaserMotive experiment shows that lasers can also keep the drones up in the air on a few watts of laser power.
New Scientist’s Jeff Hecht writes that LaserMotive won $900,000 from NASA last year by beaming power to a robot that climbed a 900-meter cable dangling from a full-scale helicopter.
The technology could help power space elevators to lift objects thousands of kilometers into orbit. With space elevators still at the concept stage, LaserMotive is keen to find other ways to turn a profit from its technology, says company founder Jordin Kare.
Flying times of conventional UAVs are limited by the fuel or batteries they can carry. Solar power with battery backup for night flight allows flight times lasting several days — defense firm Qinetiq, based in the United Kingdom, has flown its ultralight Zephyr for more than 82 hours. Hecht notes that although Swiss company Solar Impulse has demonstrated that solar power can keep even a piloted craft in the air, the unmanned vehicles typically flown by military agencies are heavier and more rugged, and so need more power to stay in the air than they can get from the sun.
LaserMotive says that ground-based lasers can deliver the required power. At last week’s AUVSI Unmanned Systems Conference in Denver, Colorado, the firm focused light from an array of semiconductor-diode near-infrared lasers down to a 7-centimeter beam, which automatically tracked a modified radio-controlled helicopter. The aircraft carried photovoltaic cells optimized for the laser wavelength, which converted about half the laser power reaching them to generate a few watts of electricity – enough to power the rotors of the little copter.
The laser-powered helicopter can hover for six hours, company president Tom Nugent told Hecht from the show. He thinks that limit is set only by the quality of the motor driving the rotors. “It’s a little consumer-grade brush motor not meant to run this long,” he says. Under laser power, the copter “flies for several hours until the motor burns out”.
“That little helicopter sounds like a nice demonstration,” says Robert Van Burdine, a former engineer at NASA’s Marshall Space Flight Center in Huntsville, Alabama, who demonstrated laser-powered flight of a fixed-wing craft in 2003. His group manually aimed the laser, but the 300-gram radio-controlled plane with 1.5-meter wingspan had enough momentum to glide if the beam drifted off target; the helicopter would fall if the beam missed it. Although many people expressed interest at the time, he knows of no follow-up work.
LaserMotive has bigger plans for extending flight duration of military craft, says Kare. “We expect we can scale to anything anybody is interested in,” including helicopters and UAVs. A craft could hover for long periods over a laser base, or fly missions and return to recharge over the laser, or fly between a series of laser bases. In the longer term, he envisions lasers powering remote ground-based sensors, delivering power to forward military bases, or supplying emergency power during disasters.
