For Sounding Balloons or Red Bull Stratos: Why not use hydrogen over helium

Back when I still had a model aero diesel engine, I was mixing fuel, 20% castor oil, 70% methanol, 10% ether, I knocked over the ether, mopped it up with a rag, left the rag on the bench...

After a while I was feeling a little "funky" and a goof I know open my shed door just as he lit a fag.

I remember this whoosh and boomph, buuga-lugs got blown across the yard and the walls of my shed has a distinct "bow" to them.

Got my first radio control a bit after that and sold my control line engines that couldn't be upgraded to have a throttle.

All the diesels went...