[xur17]

I'm not sure if you're serious, but some friends and I launched weather balloons with a payload (aprs broadcasting location) twice. Tons of fun, and there is a bunch of software out there you can use to estimate the crash location.

On the first balloon we failed to acquire enough helium, and ended up "floating" the balloon in the upper atmosphere overnight. Our prediction system kept indicating it was going to land in Africa.

[analog31]

I wonder if hydrogen would be a better choice. It's an application where the device is unlikely to endanger anybody if it catches on fire.

[sandworm101]

If you mix hydrogen and helium, say 50/50, the risk of any fire is minimal. I wouldn't smoke around it, but I wouldn't be afraid of it causing a fire in a crash. Looking at the recent shoot down, the brief white cloud suggests to me that they might have been using such a mix.

[xur17]

We seriously considered it, but were most worried about issues while we were transporting it to the launch site.

And amusingly we ran into the helium issue because our initial vendor didn't have any available, forcing us to buy a bunch of smaller, lower pressure containers from a party store. We miscalculated, assuming there wouldn't be anything left when the pressure equalized..

[moffkalast]

Likely not if you need long flight times, since it leaks out far quicker iirc.

[Velc]

hindenburg disaster comes to mind

[analog31]

I realize that, but the Hindenburg disaster happened when it landed, and a balloon that's not carrying cargo or people doesn't need to land gently. It can jettison the hydrogen before it gets too close to the ground.

[Velc]

Is it dangerous to fill a balloon with hydrogen if you don’t know what the fuck you’re doing? Because that’s me. Helium just seems like I’m more likely to keep my hair and eyebrows long term.

[analog31]

Valid point. I certainly wouldn't want anybody to get hurt, or operate outside their comfort zone. At the very least I'd say that a helium system could be hacked (still some dangers from any compressed gas) but a hydrogen system would need to be engineered (and I'm not an engineer). And note the sibling comment about hydrogen leaking out faster, so it might not be practical anyway.

[Velc]

Yep, 100% serious. Sounds like a blast. You can actually further protect the balloon with uv repellent paint to stop it popping as easily.