Hah! Your idea is nothing compared to mine! (Well, I think, cause I didn't read your post in detail) You, know Sunday brain shutdown.
Ok, here's my idea. Put a winged vechicle on a track. Propel said vechicle with an electric motor and a propeller. Now as the cart flys down the track, use the lift to crank a generator. The wings can flap up and down. Power motor and charge battery.
Nobody has ever been able to answer why this doesn't work. Consider: A 737 with 2 engines produces max 50K thrust. But it can lift and hold some 130K pounds. So in this case, you get 80K pounds for "free."
As long as your mechanical inefficiencies don't go over 80K, you get a net gain.
Please somebody tell me what's wrong with this.