In drone design, there's a trade-off between flying quietly and staying airborne for a long time. The Ion Tiger drone, which just completed a continuous 48 hour 1 minute flight, might be the breakthrough that changes this.
The reason for the trade-off comes down to fuel. Hydrocarbons (gasoline and the like) store an incredible amount of power in a small volume, which allows a drone like the MQ-9 Reaper to fly for 30 hours. Drone engines release this through combustion, a very noisy process. Quiet-running electric engines, on the other hand, are constrained by battery power, which typically limits flight time to only a few hours.
This barrier have led to a divergence of design: Big gas-guzzling drones can fly high up for long periods of time (for example, to observe an entire village), while small electric drones, though quiet enough to spy within a city unnoticed, only have sufficient energy for short missions.
The Ion Tiger works differently. Its power comes from liquid hydrogen, and is delivered in a cryogenic fuel cell specially designed by the U.S. Naval Research Laboratory. The liquid hydrogen is only half the needed fuel—the rest comes from the air around the Ion Tiger. The fuel cell combines the air and liquid hydrogen with a catalyst to quietly create electricity.
The Ion Tiger does all of this while remaining nearly silent, which means it can spy without being heard from as low as 1,000 feet. Spooky!
Another upshot to using hydrogen fuel cells for drones? Rather than needing to ship gasoline in bulk, soldiers can generate new fuel from just water, a solar power generator, and a few other pieces of equipment necessary to compress hydrogen. With such a set-up, which could be quiet small, troops could operate a drone like this indefinitely.
That's exactly what I was thinking. Why can't we get this in our homes. To generate the hydrogen the setup wouldn't be that expensive or complex. Compressing it and the catalyst are the big stuff.
@Auroria and SeekerOfTheTree
Same question here. Why cant we have that Technology in our homes?
I don't believe that the hydrogen generating process is very efficient -- that's one of the reasons that they don't use it in vehicles.
They send electric current through water to separate the elements of Oxygen and Hydrogen -- a well known process. But, you need a source of electricity.
This seems way cooler than the solar electric plane. Also can it have autopilot? Why not a true "airbus" for moving people and cargo regionally. Hydrogen is the ultimate fuel protocol.
ford2go: The hydrogen generating process is about 70-80% efficient,if you go by the artificial leaf being researched by Dan Nocera: www.latimes.com/news/science/sciencenow/la-sci-sn-artificial-leaf-dirty-water-self-healing-20130412,0,1148832.story
The problem comes from the efficiency of the solar cell it uses,and results in an overall efficiency right now of about 5%.
Duh!!! No you can't simply create hydrogen. It is a very expensive process that uses up expensive materials and energy in the process.
If some of the testing done now with TiO2 improves, there might be some limited hope.
After writing the article the author was given his pills and a lobotomy. I am pleased to announce that he will be OK (more or less )
(Dr.) Sigmund Freud
It's relatively simple to generate hydrogen with solar power, even to compress it to some extent (although compressed H2 can be a bitch to manage well) but it's huge leap to producing liquified hydrogen. Highly unlikely to ever be something that could be achieved in the field without powerful compressors and sophisticated refrigeration equipment. That's always been one of the great delusions of alternative energy sources. It's easier to convert the H2 into some other easily managed liquid fuel, like alcohol, than trying to handle cryogenic liquid hydrogen.
Kiwiiano... I'm right 98% of the time, so who cares about the other 3%?
This UAV uses a cryogenic hydrogen storage system that provides fuel to a PEM fuel cell, which produces electricity used to drive an electric propulsion motor. The conversion efficiency of this system is actually quite good. However, the total mass of this system would not be suitable when scaled up for a larger aircraft.
We should also note that while this aircraft achieved a long flight endurance, it had no ability to carry any payload.