Rockets use liquid hydrogen, which is a pain to work with, but not too bad if you can fuel up and launch relatively quickly before too much boils off. The real

Rockets use liquid hydrogen, which is a pain to work with, but not too bad if you can fuel up and launch relatively quickly before too much boils off. The real reason rockets use hydrogen is because Hydrogen and Oxygen gives the highest specific impulse of any chemical rocket. You really don't care about specific impulse in a jet aircraft, and you really don't want the fuel boiling off before the end of your 12-hour flight. Also, if you're thinking of pressurized gaseous hydrogen instead of liquid hydrogen, then the tanks get really heavy because high pressure tanks don't scale well (unlike low pressure liquid tanks which do). Hoop stress is proportional to diameter, which means tank wall thickness needs to grow with diameter too. https://www.engineersedge.com/material_science/hoop-stress.htm https://www.engineersedge.com/material_science/hoop-stress.h...