H2 (hydrogen, technically H2 but suffix slow to type!), was for a time used for efficient long-distance transport. The flying machines were ‘dirigibles' - a big word for big balloons. They were massive and able to transport tons of cargo and passengers over vast distances, albeit slowly due to their bulk, powered by petrol aero engines.
Hailed as a major triumph, there was a snag. H2 is flammable. The infamous Hindenburg disaster was just one
