Interesting concept. I assume the energy numbers work out but looking at the illustrations, having all the fuel stored in the fuselage a long way from the CG could be problematic as it burns off; yes, H2 has a higher energy density (Wh/Kg) than Jet A-1 but there is still going to be a significant mass of it. I can sort of see why they didn’t put it in the middle, like a conventionally fuelled aircraft, as it would split the passenger compartment in two, but you could engineer a corridor or such and have the tanks much closer to the CG...?