Hydrogen-powered UAV makes first flight

From the Wired Autopia blog:

AeroVironment has successfully flown its Global Observer unmanned aircraft for the first time powered by a hydrogen-fueled propulsion system. With a wingspan of 175 feet, the Global Observer is a long-endurance UAV that could stay aloft up to a week at a time according to the company.

The first hydrogen fueled flight lasted four hours and was at lower altitudes above Edwards Air Force Base in California. But the company says the aircraft would fly missions at 65,000 feet making it an observation platform and communications link over a very wide area approximately 600 miles in diameter. By combining a pair of Global Observers, each of which could fly for up to a week at a time, operators could provide continuous coverage over any part of the earth’s surface for “as long as needed” according to AeroVironment.

A liquid hydrogen powered internal combustion engine drives a generator that powers the four propellers as well as batteries and operational payloads. At the high altitudes the Global Observer is expected to fly, it would be flying above most weather and other air traffic, possibly simplifying the use of the aircraft in existing airspace.

Hydrogen has 3 times more energy than gasoline or diesel fuel by weight, however, gasoline needs 3 times less volume for the same energy as does liquid hydrogen, and 6 times less volume when compared to compressed hydrogen. The Global Observer uses liquid hydrogen. As long as you have the luxury of volume, which this aircraft has, and the storage container for the hydrogen doesn't completely eat up the potential weight savings, you end up with a craft with extra endurance. Diesel electric trains, Hybrid gas-electric automotives, now hydrogen-electric uavs all the same principle. The internal combustion engine can be operated in a narrower more efficient rpm range for the best mileage coupled with the weight advantage of hydrogen you end with an endurance leader.

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Comments

Michael Zaffuto February 3, 2011 at 7:28pm

Hydrogen has 3 times more energy than gasoline or diesel fuel by weight, however, gasoline needs 3 times less volume for the same energy as does liquid hydrogen, and 6 times less volume when compared to compressed hydrogen. The Global Observer uses liquid hydrogen. As long as you have the luxury of volume, which this aircraft has, and the storage container for the hydrogen doesn't completely eat up the potential weight savings, you end up with a craft with extra endurance. Diesel electric trains, Hybrid gas-electric automotives, now hydrogen-electric uavs all the same principle. The internal combustion engine can be operated in a narrower more efficient rpm range for the best mileage coupled with the weight advantage of hydrogen you end with an endurance leader.
Ron Jacobs February 3, 2011 at 5:22pm

Ok, I was going to say nice looking "little" airframe. then I read it has a 175ft wingspan. Kinda hard to scale that down, isn't it?

Is it using Hydrogen because of the altitude or just because Hydrogen is lighter? Is Hydrogen lighter than other fuels when it is a liquid? Do they discuss where they get the hydrogen from? Portable Hydrogen plants?
Ryan Fraser February 3, 2011 at 4:22pm

@Chris
I do not doubt AeroEnvironment's competency in engineering, just find it funny something so cutting edge uses tech that's more than 200 years old. I agree with the "use what works" philosophy.
"1807 - Francois Isaac de Rivaz of Switzerland invented an internal combustion engine that used a mixture of hydrogen and oxygen for fuel."
@Martin
It (the tech) is most defiantly not. Very close though. Just the fact an average Joe like myself can plop down $500 and buy a production PEM fuel cell is kinda neat.
Martin Peres February 3, 2011 at 3:39pm

Chris: I was only reacting to Ryan's link. Using hydrogen as a storage vector is cool but I guess it doesn't really work for small UAV right?
3D Robotics

Chris Anderson February 3, 2011 at 3:15pm

AeroEnvironment are the world leaders in airborne power systems. I'm sure that this reflects the best practical technology available.
Martin Peres February 3, 2011 at 3:09pm

Ryan: 11Wh won't get you far, also, they say nothing about the discharge rate :s Not sure the tech is here yet.
avi eight February 3, 2011 at 11:30am

One word: Kaboom!
Ryan Fraser February 3, 2011 at 11:24am

"A liquid hydrogen powered internal combustion engine drives a generator"

Seems a little "Old Tech", I've been waiting for about 8 years for PEM cells to get affordable.

Seems I won't have to wait much longer, check these out!

http://www.horizonfuelcell.com/store/hcell.htm

Just need to work out some kind of electrolysis system rather than pure H.

Cheers!

This reply was deleted.