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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!"
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
Actually hydrogen mixed with oxygen in the relation 2:1 is much worse than hydrogen as a concentrated cloud.
The Tao of math: The numbers you can count are not the real numbers.
That is.... Water!
After the explosion, yes.
The Tao of math: The numbers you can count are not the real numbers.
An RTG is only a problem if it lands on your head, those things are designed to withstand an uncontrolled reentry from space.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
It's so no pedantic arseholes sneer about them probably rounding up.
systemd is Roko's Basilisk.
RTGs, if I'm not wrong, give a small amount of energy, useful in space where you need little energy but for very long times. Not to mention their weight.
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.
I'd suggest some sort of catapult. Although I'm not sure Arduinos are the best type of ammunition.
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.
I think you where misinformed. H2O2 is not really a good fuel on its own. Too heavy for starters for so little energy. But its less safe mostly because its also unstable.
Like all mono propellants, it can break down to a more stable less energetic configuration without the need of getting mixed with anything. So say the fuel tank wasn't cleaned properly? Well we get H202 decomposition which liberates O2 and heat. Now its hotter and it decomposes faster, which produces more heat and faster decomposition.... I have personally seen this with my own monopropellant rocket.
Can you handle H202 safely? Yes. But you can also do that just fine with LH2 with the added benefit its pretty safe till you mix it with oxygen, and its has much more energy per kg. An important feature for long endurance flights.
If information wants to be free, why does my internet connection cost so much?
also if you say '48 hours' it sounds like you are approximating. but 48:01 is precise enough for people to know that you are serious.
The first man to calculate the height of mt everest calculated it to be 29,000 feet exactly. To make it sound as precise as it was, he said it was 29,002 feet.
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."