Nice images Glenn , I recall there was a story about the tube . If the rear pressurized area was blown open you would be fired down the tube like a man in a canon . The door sealed the tube as you rolled on a small cart / creeper to the tail area .
Yes, the tunnel really was interesting. I wanted to slide down to the tail gunner's seat, but it was quite narrow. It was very hot where I shot the photo, so I could imagine how hot it was in the tunnel.