Diesel in NASA's hydrogen fuel cell plane

[cRiPpLe_rOoStEr]

Originally Posted by freebeard

But starting at a high altitude, at high speed, there is a lot of energy to be regeneratively captured descending to rest. Which can be reused by the efficient tail engine back at cruise, after the extra wing engines idle back after the climb.

Considering that sometimes in case of a flame-out the inertia and the impact air flow are enough to drive the rotating mass while the engine is re-started, that sounds like a quite good opportunity to try some sort of hybrid setup for the aircraft.