Boeing B17 Electrical system
One of my apprentices (a German!!) informs me that the B17 (by my understanding is considered an 'electric aircraft' as compared with the B24, an 'Hydraulic' aircraft) did not have a 'ships battery', but had a small twin cylinder? engine (APU) driving a generator of some sort to start the Powerplants, and therfore be the only emergency back up in flight.
I find this very hard to accept, can anyone enlighten me (or possibly him!!)