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Liquid Hydrogen Powers a UAV For a Cool 48 Hours
An anonymous reader writes "While liquid hydrogen may not be a mainstream fuel for drones, the aerospace industry has said it holds the promise of flight endurance on the order of days, seemingly just another far-fetched aerospace industry pitch ... until now. The Naval Research Laboratory just announced that the Ion Tiger, a diminutive 37-pound airplane with a 17 foot wingspan, flew for 48 hours and 1 minute on liquid hydrogen and a fuel cell (anyone else notice the oddly specific duration? Guess it's better than 47 hours 59 minutes). This is a dramatically different scale than the liquid hydrogen powered 150 foot wingspan Boeing Phantom Eye and 175 foot wingspan AeroVironment Global Observer, which have yet to live up to their multi-day endurance projections. Interestingly enough, the well-known Global Hawk only has an endurance of 33.1 hours, which barely cracks Wikipedia's list of notable UAV endurance flights. Of course, solar-electric airplanes have flown for two weeks continuously, but that sure seems like refueling!"
Why would you think so?
Does the idea of planning a '48 hour flight', and then spending a minute extra on landing after achieving the mission goal, seem strange to you?
I think I heard it's more dangerous than handling pure hydrogen peroxide. One miss-step and boom!
How about you try to use units that make sense? Here's a diagram that illustrates the sillyness https://7chan.org/sci/src/132255181954.jpg
So 48 hours is some kind of record for a UAV??! I thought they could stay in flight for weeks at a time...why don't these things have RTG's, like voyager?!
The QinetiQ Zephyr laughs aloud at this with its two week high altitude endurance record. There are several two day platforms out there, look harder ;-)
http://www.suasnews.com/2010/07/470/after-14-nights-in-the-air-qinetiq-prepares-to-land-its-zephyr-solar-powered-unmanned-aircraft/
Someone please come up with a small Arduino solution to shoot them down.
Great comments :-) - notice how the navy's own page says "The craft shattered all previous endurance records [having previously noted the navy's 40-minute flight in 1924] performed by similar, propeller driven, fossil fuel and battery-powered UAVs by completing an uninterrupted 26-hour flight carrying a five-pound payload."?
Of course, solar-electric airplanes have flown for two weeks continuously, but that sure seems like refueling!"
Come on, that's terribly unfair! Refueling as you fly is not the same as having to return to base...
The Global Hawk is the size of a 747. The Ion Tiger is a small lightweight drone with a 17" wingspan. And the Phantom Eye is large at 150" wingspan, but also described as lightweight. Comparing flight duration seems a bit unfair. Anyone have a better idea how to properly compare efficiency of engines?
Tic-Tac-Toe, Global Thermonuclear War, and relationships all have the same winning move.
"anyone else notice the oddly specific duration? Guess it's better than 47 hours 59 minutes"
Well, yeah...
More than 2 days is and obviously sounds better than less than 2 days.
How is it an "oddly specific duration"?
You would've picked less than 2 days and used "47 hours 59 minutes"?
It flies at 300 knots and weighs ~30,000 lbs (~14,000 kg).
I worked on the NASA Global hawks for a few years. They are incredible aircraft and certainly not in the class of the toys it is being compared with. Predator comes close (I was on an effort to put a sensor on the NASA Predator but funding got yanked) but Predator doesn't have nearly the capability of Global Hawk.
I am very small, utmostly microscopic.
The odd minutes may add up but I suspect it sounds better in marketing-speak: "Over 48 hours!" sounds more impressive than "48 hours 1 minute" or "2 days" perhaps?
Plus as somebody else had noted maybe there's a government contract which specifies money will be given if a prototype can be shown to run for at least 48 hours. Over 48 hours? 48 hours 1 minute, send us the money!.
I worked with this group and I can tell you they're not into marketing, but the press people that prepared the release probably are.
The bulk of what this NRL section does is technology demonstrators. They were also the first to air drop a drone from another drone. The odd number is probably an exact accounting of the time spent on powered flight; climb, cruise and loiter segments are the most significant for accounting for energy use during flight. Gliding and coast segments are not so interesting.
Props to my old crew at NRL, and to the memory of Jim Kellog who developed the first prototype of what became the Ion Tiger.
"Now, I doubt any of you would prefer a rolled up newspaper as a weapon against a dictator or a criminal intruder."
Yeah, I've spent some quality time navel gazing myself.
[x] cheap
[x] useless
[x] have pointy edges
I say man the catapults!
CLI paste? paste.pr0.tips!
Anyone want to cover a bet that in the contract, a large amount of monies were to be paid after a flight duration time greater than 48 hours? Just sayin' is all.
The liquid hydrogen can be used to cool the infrared sensors as well.
Not sure that says much about the power system.
The plane appears to be very close to a sailplane. Drop the weight a bit and i think it would run on watch batteries and thermals.
17 feet is a lot of wing for 40ish pounds of airplane.
hmm, can we make a powered glider that can find a big thermal and reverse the circuit to recharge a battery in a dive?
Sounds like an easy hybrid: Add solar panels to a fuel cell to extend range (or fuel cells to a solar-power plane, depending on your design criteria)
Those odd factor-60 minutes and hours should die
There has been an attempt at decimal time during the french revolution, but it did not catch up