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Stalker UAS flight time improved by 2,400 percent using laser beams


July 11, 2012

The flight time of the Stalker UAS has been improved by 2,400 percent using a wireless laser beam power system (Photo: Lockheed Martin)

The flight time of the Stalker UAS has been improved by 2,400 percent using a wireless laser beam power system (Photo: Lockheed Martin)

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Late last year, DARPA researchers upped the standard two-hour endurance of Lockheed Martin’s Stalker small unmanned aerial system (UAS) by a factor of four using a propane-fueled compact solid oxide fuel cell (SOFC). Now the flight time of the aircraft has been improved by a whopping 2,400 percent, with a test flight lasting more than 48 hours using a laser power system to wirelessly transfer power to the UAS from the ground.

The indoor flight test saw the Stalker UAS modified to incorporate a Power Link system developed by Kent, Washington, based company LaserMotive. The system sends a beam of laser light from a ground station, through the air to a receiver of photovoltaic cells on the UAS. The system can provide continuous power to the UAV while it stays within range of the ground station and can also charge batteries onboard the UAS to allow it to fly beyond the range of the power link.

In fact, the indoor flight test, which was held in a wind tunnel, finished with the Stalker’s battery having more energy stored than it did when the flight began. With the system providing the potential for practically unlimited flight time, the flight test was only concluded because the initial endurance goals set by the team had been met.

“This test is one of the final steps in bringing laser-powered flight to the field,” said Tom Nugent, president of LaserMotive. “By enabling in-flight recharging, this system will ultimately extend capabilities, improve endurance and enable new missions for electric aircraft. The next step in proving the reality of this technology is to demonstrate it outdoors in an extended flight of the Stalker.”

With the ground-based laser powered by a standard industrial electrical outlet or a generator, there is potential for it to be positioned at a base or on the back of a vehicle in the field. While there is a significant loss in energy when transferring power between two points near the ground using the system due to turbulence and dust, LaserMotive says that power beamed vertically suffers relatively little energy loss as it quickly gets away from ground effects. The company is even working on systems to beam power from the Earth’s surface to satellites and even the Moon.

Source: Lockheed Martin, LaserMotive

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag. All articles by Darren Quick

First steps towards to space elevator!

David Anderton

Okay, remote powering via lasers? Why isn't this revolutionizing electric-powered transportation of all kinds? Our "flying cars" could be electric!

Also, sending power from earth to a satellite? What about the other way around, folks? A geo-stationary satellite loaded up with solar panels and a high powered laser beamin' that stuff down to a collector on earth! Here's where we need the power, not up there! :-)


Wouldn't this allows the stalker to be easily targeted by laser guided missle?


Great! This is the future of energy transfer! Much reduced weight. Just like the electric train, trolley bus, etc. The system may have issues with weather and clarity of air, though.

But on a larger scale, the fixed energy sources for transportation has huge benefits. The same reason why electric vehicles can get their power from lines while on express ways, making range a non-issue. That will be quite like those electrified track toy racing cars we had as kids.

Nantha Nithiahnanthan

A 1 watt laser is considered to be dangerous. Powering a small car like this would need at least 5,000 watts of laser power. A flying car, much more. Either would be insanely dangerous in a city.

David Evans

When you start talking 5000 watts of laser output you have to consider the efficiency of the laser. We used to get 10% efficiency out of a CO2 laser so you would require 50,000 watts to generate the 5000 watts.

People are complaining about the the hazard windmills are to birds but can you imagine the pile of roast duck you would have with a 5000 watt laser.

I think the low power system is ingenious but let's not get carried away.

Mr E

Too bad we can't get this type of funding for innovation in products we can actually use.:| A good use for this technology would be for an airborn wireless router to serve broadband internet competitively. Don't think it will happen though, ATT, Cox, Verizon etc. would use their political influence to get the FAA to nix it.


This system is so dangerous it should be banned. Some poor pilot passing anywhere above it would be permantly blinded or any bird roasted.

Next the costs are huge.

One would be 100th the cost just by using 2 battery powered ones, one being charged while the other flys at 10% of the foolcell version or 100th, maybe 1,000th the laser version.


I think it's time to look at tesla's work on radiant energy transmission


"Why isn't this revolutionizing electric-powered transportation of all kinds?" Because the efficiency is too low, and the costs are too high. Fails the back of the napkin rough calculation test, sorry.

Captain Obvious

Can somebody make a lawn mower in this way. :)


re; MrGadget

First you probably won't be charging the drone while it is over the enemy. Second the missile probably costs more than the drone so if they do shoot at it they are probably up to something. Third if the drone observes the launch or gun firing the drone can make an evasive maneuver that the laser won't follow but will instead will look for something else to illuminate. Forth a few rounds of 155 retaliation will tend to discourage that sort of thing.


What about power applications for remote islands or distances? I can see where you can shoot a laser to an outer island from the mainland which has a receiver that can charge up batteries which discharges into the island grid. When battery charge is near depletion, it can send a radio signal back to the mainland to fire up the laser again to recharge the batteries.


Sounds nice to send packets of energy > The laser has worked in a controlled lab environment by "line-of-sight" principle directed at the drone, and to avoid high power loss, it is claimed that it will be applied vertically upwards in the atmosphere. In practice, how will the ground transmitter be vertically "below" the drone always ? Secondly, assuming the drone is at a sharp angle (say 10 degrees with respect to the ground and land-based transmitter) , even if it is still technically in the line-of sight , will there be a tall transmitting tower or something to keep transmitting? Thirdly, would there be a huge ramp-up knob to turn on a gigantic laser transmitting power proportional to the angle subtended by the drone ? Fourth- how would the laser beam exactly impact the environment - (poor birds) . Fifth- with such huge power flowing through layers of oxygen in the atmosphere -will it increase conversion of oxygen to Ozone which is bad for us?


re; jerryd

1) It is relatively easy to protect eyes against known lasers. 2) The laser operators will be soldiers not malevolent morons. 3) Everything except enemy operations and small arms fire that flies in the battle space is subject to a combined service air traffic control, so only a stupid or very unlucky allied pilot would be blinded by our laser system. For enemy pilots and our pilots going amongst enemy laser systems it is just a risk you take when you fly in hostile or disputed airspace. 4) Assuming that the system ever makes it into civilian use it will be in the hands of licensed operators and again not in the hands of malevolent morons.


re; ted96799

The article clearly stated that ground to ground energy transmission is impractical do to atmospheric dirt.


Lots of people are a bit confused about what this is really about. The power for this (hand launched) "model airplane" is generated by a few solar cells illuminated by the laser. Can you imagine how many solar cells would be required to power a flying car? Or to power an aircraft the size of the drones now bombing folks in Pakistan? This technology is certainly nothing new - the solar cell was invented 130 years ago and the laser over 50 years ago (interestingly, Einstein was involved in developing both these technologies). Unfortunately, it's use will forever be limited to small craft such as the Stalker due to it's low power capabilities. Tesla's ideas on long distance power transmission via induction are more likely to result ultimately in large scale remotely powered devices. Induction has long been used for very short range and low power devices from RFID chips to electric toothbrushes and many more. But I think it will be a long time before Tesla's ultimate promise is fulfilled.


If you use two lasers to generate the plasma conductor trails you could then send electricity directly and very fast.


Why an optical laser and photovoltaic cells? I would think a maser and rectenna combination would be more efficient.


we have a high efficiency, mulifuel, inexpensive, robust, high HP/weight turbine for long duration aviation, heavy lifting. First app we are evaluating are not aviagtion, because of economics. Interested in interested parties. sannerwind@gmail.com

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