[__MatrixMan__]

I've flown hydrogen balloons before (just because it was cheaper than helium--although you do need different fittings for the tank). I've also lit them on fire just to see what happend.

I don't think they're as dangerous as people think. If they ignite they go up in a whoosh, not a bang. The only debris is your payload, now falling. So as as your payload is not also made out of flammable material (as was the case with the Hindenburg) then I don't think it's any more of a fire threat than having power lines near trees is in the first place. Up is conveniently the right direction for a ball of flame.

Of course all of this goes out the window if you let it become entangled in a tree...

[ThomasLaporte]

That's awesome! In what situation did you had the opportunity to fly a H2 balloon?

Do you have any video that you could share about the lighting on fire of the balloon?

[__MatrixMan__]

A bunch of friends and I wanted to get video of a balloon's flight as it approached outer space, popped, and descended. In violation of FAA rules, we used a cellphone which we had embedded in a styrofoam box with hand warmers in order to prevent the battery from freezing.

We lost contact with the payload almost immediately and never recovered it, but lost enthusiasm to try a second time.

We had bought two balloons just in case we needed a second. Waited for a rainy day and took the second one camping. I wish I had grabbed a video, but some among us were overly paranoid about creating evidence.

It was just a big blue orb and a whooshing sound. Presumably there were some flaming bits of rubber involved but we weren't able to recover them (we made the tether too long, out of fear for it being more dramatic than it was, that it was hard to get a good idea of what specifically went on).

Has there ever been a burning man effigy with a lighter-than-air component? That would be a good venue for exploring the dynamics of baloon fires (it could tethered such it wasn't above anybody when it went up).