Hey Guys,
The Chyenne Tail Turrent was not remote controled or powered. Here is a link I Googled and it has some great interior shots and a shot of the older tail turrent with the vertical armor plate the gunner reached around to fire the guns. The Chyenne tail guns were set up pretty much the same on pivots except the mount was brought in closer to the gunner where the fuselage was wider enabling a larger field of fire, and the cavas replaced with streamlined ball cover.
http://01f15b4.netsolhost.com/b17_turret.htm