All the energy in this system is initially coming from the APU to charge the battery, so you may as well drive the rotors from the APU and save the battery and electric motor weight.
The idea was to charge the battery from the ground and have to APU just keep it topped up. Only in a remote area where no electricity could be found, would the APU be running to charge the battery up.
Pretty much like the Chevy Volt that comes out now.
But it is much worse than that. There are significant energy losses in the electric generator and then the electric motor, so the fuel efficiency overall is much worse than a plain ol' turbine.
Yes, there are energy losses, but so are there in gearboxes. I have a hunch the APU and Gen will weigh less than a gearbox, but I could be wrong.
As for the Prius - it's a gimmick. You will get better overall efficiency in the *real world* out of a small modern turbo-diesel.
This is true. However, may I make a direct comparison to the field I work in - Cinematography.
All these new HD cameras and digital stills cameras have come along and pretty much put film still cameras out of business. Most of you probably have an old film camera laying around in your house, but you shoot on your digital cameras these days. Film cameras for the motion picture industry is still hanging on, but their days are numbered. Now, do any of these HD or still cameras resolve more pixels than film or actually look better? No they don't. In fact, the latest HD cameras have far less resolution than film has. I can easily extract 6K information from a 35mm film frame, whereas an HD camera barely manages 2K, and that's heavily compressed. Yet they've completely taken over. Why?
Because it's good enough and convenient.
Now, would you rather not have a little bit less range in your helicopter, if you could virtually eliminate TBO's on drive components? If you could tenfold reliability? If you could fly for half the cost? I think most business and individuals would be happy to make that trade. And that's where I think electric cars, aircraft, whatever will live in the beginning. It's an interesting future, for sure.