I also like the bonkers phase between the "just take a gun with you" era and the synchronizing gears. Seems to have boiled down to three or four ideas:

1. Pusher prop and/or an extra 150 pounds of human to work a turret.
2. Hope you don't completely destroy your propeller before you defeat or fend off your opponent.
3. Slap some armor on it, then proceed with plan #2 with somewhat more hope, though now with the possibility of richochets.
4. Mount a bizarre triangle thing to the back of it that will deflect the bullets in a somewhat less suicidal manner than simple metal plates.