Can someone (preferably who knows what they are talking about) please explain what the point of hybrid (ie turbine/electric in this case) drivetrain on an aircraft is? In a road-going vehicle, particularly one in an urban or semi-urban context where it is doing a lot of stop/go driving or going up and down hills, levelling the energy demand from an ICE to its most efficient RPM and leaving it there makes complete sense. The excess energy the engine then provides over what the vehicle needs - when it is running - is used to charge a relatively small battery which is later used for periods of high energy need eg accelerating or going up hills. If the engine is not needed, it turns off and all the motive energy comes from the battery.
In an aircraft, you climb out, set your throttle for whatever speed you want and it pretty much stays there for the entitreity of the flight; your engine power matches your drag for a given altitude and that’s that (-ish). So, what the Dickens is the point of a hybrid ‘drivetrain’?