[usrusr]

But that big max/cruise delta disappears as soon as you ditch the wings and go 'copter, which seem to dominate all use cases where electric is anywhere close to viable.

Where motors excelling in W/g could absolutely shine is the still empty area of hybrid planes that downsize their combustive propulsion to cruise requirements and carry batteries only for those short periods of peak power demand.

[sitkack]

Would you use a generator or a directly connected ICE?

[usrusr]

Certainly not a generator, at least not unless there was some miracle fuel cell fuel. The "electric boost" would need to be completely idle most of the flight (which creates some interesting challenges regarding conversion of electric torque to air movement).

[sitkack]

This is a fascinating analysis of hybrid electric planes

https://link.springer.com/article/10.1007/s13272-017-0272-1

I think the idea is worth exploring. Esp with superconductors an electric powertrain could have lower losses than mechanical.

[usrusr]

Oh, that's sobering. All the referenced modeling seems to start with hypothetical batteries many times lighter than we have, and even then they only give minor emissions reduction hardly beyond what we are used to from e.g. succeeding generations of 737. And only under the assumption that the electricity used is completely emission-free.

And why even bother modeling constant power split? You might just as well linearly interpolate between conventional and an all-electric design and call it a day. Everything interesting about hybrid propulsion happens when the ratio is varied with power demand.

What's interesting is how much mass they account on the electric side in addition to the battery. This kind of validates H3X.