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!"

Comments

Re:Wait..what?!

[TapeCutter]

An RTG is only a problem if it lands on your head, those things are designed to withstand an uncontrolled reentry from space.

Re:There's nothing odd with 48 hours 1 minute

[wonkey_monkey]

It's so no pedantic arseholes sneer about them probably rounding up.

Re:I think liquid hydrogen is dangerous as hell

[delt0r]

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.