Don - you're the closest. Well done sir!
After much reading and googling, I learned this unusual B-17 was the result of the 1944 "Reed Project"; the aircraft is B17E (41-9112), with a Consolidated nose and tail turret, powered twin guns in the radio compartment, Martin top turret, and bi-fold bomb bay doors. The "accordion" doors made it harder for the enemy to tell when/if the doors were open.
View attachment 26029
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Here's a forum reference to the Reed Project, with several photos. Note the notched vertical stabilizer:
https://www.warbirdinformationexchange.org/phpBB3/viewtopic.php?t=25972
You can also see that Fortress on the ground with B-24s, in Lancashire England, 10 March 44. Page takes time to load; click right arrow after photo loads.
https://www.fold3.com/image/#32443380
The story:
The Reed Project (under the direction of Major Robert J. Reed, Engineering Officer at the 8th AF Depot at RAF Bovingdon) was an effort to incorporate major defensive change ideas into the B-17 air frame. Reed was put in charge of the Project and was allocated an early B-17E to work out the bugs. He flew it back to Wright Field for the mods to be installed and tested.
The changes included a Consolidated A-6 Nose Turret, realignment of the bombardier position to an almost prone position under the fuselage , removal of the waist guns and replacement with a pedestal gun in the radio room, replacement of the tail gun with another A-6 ( The rudder had to be notched to allow for the turret movement) , and replacement of the Boeing top turret with the Martin Turret . The changes made a really ugly airplane out of the normally shapely Queen.
The machine was not a success, and only one of the changes (The Martin Top Turret) was incorporated into the F or the G model. The Bendix Chin Turret, under development in 1942, was field tested in the YB-40 , and was a great improvement over the A-6. It was incorporated into the B-17G production.
Tom