Looking for a reason to put up a balloon and payload into near-space? Not that one’s necessary, but the Global Space Balloon Challenge has got a variety of good reasons for you to do so, in the form of prizes and swag from their sponsors. Go for highest altitude, best photograph, longest ground track, best on-board science payload, or a bunch more. Have a look through the gallery to check out last year’s winners, including teams that dropped a 3ft paper airplane or floated an R2D2 replica.
Basically all you need to do is register on their website and then go fly a high-altitude balloon between April 10th and 27th. Last year 60 teams took part, and this year they’ve already got 90 teams from 31 countries.
And if you’re just getting into the (hobby? sport?) of high-altitude ballooning, be sure to check out their tutorials and forum. Of course Hackaday has been covering folks’ near-space balloon efforts for a while now too, so you’ve got plenty of reading.
So what are you waiting for? Helium’s not getting any cheaper and spring is on its way. Start planning your balloon launch now.
What I have thought about doing is chemically generating hydrogen lifting gas.
I know that Water with Lye in it reacts with Aluminum to produce lots of Hydrogen gas. This would be a cheap way of generating lots of hydrogen it seems. Any hydrogen electrolysis cells I have made produce HHO at far too slow a rate to fill a balloon, and wouldn’t lift as well because Oxygen would be in the gas too.
What I can’t find anywhere on the internet is how much water, lye, and aluminum would be needed to fill a reasonable lifting balloon.
Make sure the balloon material is not permeable to hydrogen. People who try to make trash bag hydrogen blimps end up with flat blips within a day because all of the hydrogen leaked out, although it was perfectly sealed.
That’s the real problem isn’t it, gas leakage, if you could keep all the gas in the balloon it would float forever, but is there any material that can hold a lifting gas forever (well without being a steel tank or something.)
Mylar is probably the best you can get. But that, too, leaks.
Mylar is probably the best you will find, although the aluminum film would eventually suffer hydrogen embrittlement. It’s much more impervious than plastics to even small gasses, which is why the food packaging industry uses them for so many things that react with the air. (chips with long shelf lives, almost all chocolate, etc.) Also, the Echo 1 satellite just looks awesome!
No floating forever, balloons quit floating when they get high enough to expand to point where they burst.
I never really understood why the difference in permeability. Isn’t an H2 molecule physically much larger than an He atom? The only hydrogen that should leak quicker than helium is ionized hydrogen, no?
That’s for helium, which can sneak out of almost anything, like Mylar that isn’t coated with aluminum. Hydrogen atoms comes in pairs, H2, which is much much bigger than a helium atom. Also, hydrogen is cheap and used in welding and as the atmosphere in silver-solder ovens that need super clean parts. I have wondered why people don’t routinely use hydrogen for these balloons. You even get some more lift for the same volume.
Zinc and hydrochloric or sulfuric acid was used in the 1800’s. A tank from the local welding supply is easier.
If you want to make your own, decide how many liters at STP, calculate moles needed and look at the reaction, get the mole ratio and the atomic weight of aluminum (or zinc if you are doing that much easier reaction). Check your chem book under “stoichiometry”.
For Al and NaOH, 2 moles of Al for 3 moles of H2. Basically, 18 grams of Al for every 22.4 liters of H2 at STP. It starts slow as it converts the aluminum oxide layer then gets hot and fast. I can’t recommend it without apparatus to cool the reaction and dry the gas and keep yourself and those nearby from being sprayed with Drano (one type of which has aluminum chips to make it boil in the pipes – don’t use that) which can leave interesting scars or great stories to tell about why you are blind.
That one mole of gas is less than 1 cubic foot at STP (28 liters). A typical balloon can use a K-type cylinder to fill, which is about 200 cubic feet, so you need to react nearly 4 kg of aluminum with 8kg of NaOH and 2kg of water will also be used up and you will have some intriguing waste. That’s a back of the envelope guestimate and check for factor of 2 errors. You can see that buying some dry hydrogen is probably a lot easier – a K cylinder is around $50 I think.
I just hope that this stupid waste of helium stops. Helium is such a cool gas, because of it’s low boiling point and inertness, which makes it the perfect working fluid in cryocoolers and Stirling engines. So it’s somewhat sad to see it wasted in m³ quantities to fill (party)ballons/airships or used as welding or breathing gas. Once in the atmosphere, it’s basically lost, since it will bleed into space soon.
Why not use hydrogen for ballons?? It only has 0.5 the weight per volume of helium, less leakage and isn’t dangerous, as long as it isn’t mixed with air. And it only costs a tiny fraction the price of helium. So please use hydrogen and leave the helium to those who really need it and who can recycle it.
Anybodysguess you are a gentleman and a scholar sir, Helium is used as an analytic gas and should not be used for a stupid “look a baloon herr durr, SCIENCE, hurr durr” Hydrogen is completely safe and has more lift, it would probably be easier to just rent a bottle of hydrogen from a gas supplier than generate your own.
No, the Hindenburg is a very poor example if you want to be afraid of hydrogen… A balloon has no leaky valves or shafts to worry about creating an explosive mixture. That being said do not vent a hydrogen bottle directly to atmosphere as the gas can spontaneously ignite by friction in the presence of oxygen. Also the flame is often not visible so be careful.
TLDR use hydrogen, helium is for analyses.
I have worked with hydrogen quite a bit, and know exactly what it is capable of. And I would still say not to use it in party balloons. (I think the whole concept of party balloons is pretty dumb) but for lifting weather balloons and other balloon projects and blimps it SHOULD be used. It is better than helium for lifting in every way.
I have done this and it is simple. I used a pe decorating sheet to make the balloon and a small custom rig to generate hydrogen. The problem I had was getting water into the balloon and I reached the conclusion buying hydrogen was easier and worth the price.
I’ve looked into this too for our launches at HacDC. Bought some super-thin mylar from the hobby store, glued it together. Filled with H2 made from aluminum foil and HCl. There’s two practical issues. These aren’t really a problem for a gallon-sized balloon, but a total PITA for anything that’ll be lifting.
The aluminum / acid reaction is exothermic and really wants to run away on you, so you have to cool it down. But if you need to generate a lot of H2 fast, like if you’re inflating a weather balloon on a slightly windy day with a team of ten people all trying to not get their skin oil on it, you don’t have time. So you’d have to run the reaction hot, but not too hot. Which means boiling / fuming HCl, which is a bit hazardous and…
The HCl fumes need to be kept out of the balloon, so you’ll need to bubble the first-stage gas through some cool water or something — essentially like a bong — to filter out the caustic steam to keep your balloon from getting damaged. If you want to do this in quantity, you’ll need a really big filter. This is also a hassle.
So you’re trying to keep an unstable reaction right on the knife-edge by cooling it down just enough, while running the resulting gas through a pressurized bong. Again, it works great for filling party balloons, but it’s touchy to scale up.
OTOH, renting a tank full of H2 is dirt cheap. Cheaper than helium, and lifts more too. As long as you keep your oxygen and hydrogen separate there’s very little explosion risk, although it will make a righteous fireball. So handling the H2 requires some safety precautions, a lot of coordination, and probably a couple dry runs, which is why most balloonists just use helium.
I guess a big question would be whether the gas generated is sufficient to provide enough lift to offset the weight of the supplies.
I’m too lazy to implement it, but here’s my idea:
Solar powered hydroxy (2 H2O –> 2 H2 + O2) blimp that floats around and does other sciecey stuff.
A solar powered wing is marginally possible with only the best of science, but by cheating and using a lighter-than-air gas you could stay afloat indefinitely.
Hydrogen leaks less than helium, and all you need is a water source (most of the surface of the planet) to regenerate your lift gas. If you physically separate your electrodes (like in a a pair of connected vertical tubes like an “H”), then the oxygen will bubble up one tube (discarded) and the hydrogen up the other (captured).
Free power from the sun. Free lift from water. Lasts forever.
I don’t know why so many commenters think hydrogen is prone to leak through balloon walls. It will stay in a toy balloon for ages compared to helium (He is good for one day if lucky. Before the Mylar/aluminized stuff kids were pretty disappointed the next day). The H2 molecule isn’t that much bigger compared to the helium atom, but it just happens there are a lot of “holes” in stuff that a helium atom can get through and a hydrogen molecule can’t. Maybe it is the shared electron and electric field interactions. I don’t know for sure, but the result when it comes to effusion through a material, H2 sometimes acts as if it is huge compared to helium. You would expect it to leak at 0.7 times the rate of He. Maybe when H2 reaches the outer boundary of the membrane, it runs into an O2 and a little UV and bang, an H2O plugs the hole for a while :-) Now I want to do some tests…..
Do u realize how heavy water will make our balloon ?
My thought,
Use the balloons to lift a small launch platform with a multi stage model rocket on board. Once at the proper altitude, send the rocket into low orbit.
Another thought for more height, use a multiple stage balloon. Once you get near bursting presure, bleed the excess hydrogen into a second ballon, so you can stay afloat and maintain positive buoyancy.
Also known as a “Rockoon” (which is pretty cool):
http://en.wikipedia.org/wiki/Rockoon
Permeability isn’t really a problem because most high altitude balloon flights are of short duration. People don’t use hydrogen because of the danger. It is odorless, colorless, burns with a near invisible flame, and will burn in a wide range of concentrations. Chemically manufacturing hydrogen requires a stage to filter out the water and other chemical vapors which end up mixed with the hydrogen due to the heat involved.