zlacker

I wish the regulations around HAB were not so lighter-than-air gas centric. Hot air balloons are much more accessible, especially solar heated hot air balllons. But they have much less lift per volume and so the FAA FAR 101 rules basically say they all have to be treated as the type where you inform the FAA beforehand and then every hour about their position among other things.

https://www.ecfr.gov/current/title-14/chapter-I/subchapter-F...

>any balloon that is moored to the surface of the earth or an object thereon and that has a diameter of more than 6 feet or a gas capacity of more than 115 cubic feet.

And the regulations on tethered balloons end up being even stricter than letting them go.

>>superk+(OP)
FAA wants you to use hydrogen. >roll safe<

>>superk+(OP)
As well they should be. The tether represents far more of a risk to aviation than the actual baloon. Not only it is much larger a collision risk, it cuts through GA airspace where all the delicate stuff flies.

>>daemon+b5
Okay, though, for very small hobbyist payloads, though, wouldn't hydrogen balloons be feasible?

Some quick math tells me that you can lift approximately a kilogram of mass per cubic meter (at sea level, anyway). If your balloon's full weight is a half of a kilogram, you'd only need about a large beach ball filled with hydrogen to lift it. That seems like something that would be attainable for an outdoor DIY electrolysis setup.

>>maples+cG
Oh for sure - in fact I believe weather balloons usually use hydrogen (not for demos, but for large scale/daily actual weather purposes). It's just amusing that the regulations effectively encourage use of the more... energetic lifting gas.