First test flight of largest all-electric aircraft used just $5 of electricity

I can understand a hybrid train because of certain sections of track electrification issues and the fact that diesel electric is how even trains that run entirely on diesel operate so you’re essentially just toting around a generator to operate your already electric engine. I understand hybrid cars with regenerative braking and range extension. I don’t really understand hybrid planes.

Like I can imagine electric is more efficient for takeoff because electric engines produce more initial power generally than what fossil can match per engine size(a big part of both hybrid trains and cars both using batteries for initial acceleration) and then you cruise with jet fuel. I’m just having a hard time imagining it is worth it from a defossil fuel perspective or from a straight efficiency perspective.

Combustion engines have maximum fuel efficiency at a specific RPM. A Hybrid has the advantage that you can run that engine at maximum efficiency 100% of the time and using the generated electrical energy to generate motion. The gains by being able to keep the ICE at peak efficiency are more than the loss you take from the conversion. That’s the same principle as in hybrid cars - look up Technology Connections video where he analyzes the behavior of his hybrid car. It is for sure preferable to than just the ICE directly, losing a lot of efficiency and therefor fuel because of differences in needed power output. Combining this into a plugin-hybrid makes - as you said - the takeoff use no jet fuel at all.

This will not eliminate the need for jet fuel, but even a reduction is preferable to the status quo. Until we get batteries that are light enough while keeping energy density at least as high as now (preferably higher), purely electric long-range flight is not an option that’s available.