A possible future power source for passenger airline aircraft is liquid hydrogen, and assuming we solve the safety and infrastructure issues, it's doable and much less sci-fi, as for example, a Martin B-57B flew on hydrogen rather than the normal jet fuel, and so did a converted Tu-154 airliner.
However, a brief youtube and web browsing session(nothing as deep as scientific papers) shows me that while the mass to energy ratio is superior to current jet fuel, the volume rather is still terrible, even when cryogenic, meaning that the tanks would need to much more larger, in terms of volume.
Airbus proposals all use a flying wing design, which has the capability to have a much larger internal volume. However, I'm not sure if it would be possible to make a flying wing as maneuverable and as tolerant of high g force as the standard fighter jet layout, due to the longer wings and greater frontal surface area. Since my scenario is around 2050, what would be possible near-future designs future Liquid Hydrogen fighter jets? My starting point is "fifth-generation" fighter jets, which have anti-radar coatings for stealth and slightly different geometry to scramble radar signals, but most importantly, can not have fuel tanks and weapons hanging off the side during flight. That means everything, even all fuel tanks must be inside the aircraft.
For the base of the design, I'm looking at current 5th gen aircraft, like the F-22, F-35, Su-47, and J-20. The J-20 looks the most "chonky", and maybe with a smaller jet engine, I could squeeze multiple large volume fuel tanks, enough to match the flight time of current 5th aircraft? But could you all be be willing to provide input or maybe even just rough sketch for viable designs that use Liquid Hydrogen?