Aero Vintage Books

I posted this in conjunction with the post about lack of waist gun blisters on some B-17Bs.

The ultimate B-17B

What is interesting about this photo is that it depicts the Sperry remote turret system being developed for the B-17C that never made it into the B-17. The Sperry remote turret system was a parallel development to that being done by GE for the system that ended up in the B-29 and A-26.

See also this link from an earlier discussion about this armament in the December 2008 B-17 News: https://www.aerovintage.com/b17news8.htm

Jumping into the history of putting gun turrets on B-17s, the Air Corps was working with Sperry and Boeing in 1940 to get a central fire control system into the B-17C, with low-profile remote control turrets installed behind the cockpit and on the belly of the bomber. Low profile turrets were desperately needed to reduce the drag of the defensive armament and still provide an effective powered defense against the airstream and environment of high altitude bomber. Sperry and Bendix and GE and a bunch of other companies were working on fire control systems for Air Corps bombers, and the GE system was developed for the A-26 Invader (edit: actually slated for the A-20 initially) and B-29 Superfortress, even then on the drawing board in the 1940-41 period, while Bendix was working with North American for the lower turret for the B-25. Well, the B-17C was slated to get a Sperry central fire control system, suggesting that the common wisdom (commonly incorrect) that the B-17E was the design response to the RAF's experience with the B-17C in combat with the Luftwaffe in 1941. The Air Corps long knew of the deficiencies in the B-17 (and other types) defensive armament and was desperately seeking to get powered turrets, preferably remote control turrets, into the bomber.

Unfortunately, technology just wasn't where the Air Corps needed it to be in 1940, particularly with turret drives and the precise control needed for accurate defensive fire. The central systems lagged far behind the B-17C schedule, and then the B-17D schedule. What was left was Sperry designing a manned upper turret for the B-17E, and the remote, locally controlled turret for the belly. Plans for the central fire system were ebbing away from the B-17 and moving on to the B-29. Sperry was also working on the manned spherical (ball) turret, and it was the obvious solution to provide a turret on the belly. Development of the ball turret was only a few months behind the Sperry remote lower turret, so the Air Corps had Sperry build 113 of the remote turrets for installation on the first 112 B-17Es (one spare for testing??), and then the Sperry ball turret would go in the rest of them. This was all laid out well before the first metal was cut for a B-17E--the Sperry contract was signed in December 1940--the first B-17E flew in September 1941. And, by the way, look up at that technical order, last sentence, and note that "provision has been made on these turrets for the interchangeability with the spherical turret." So, it was designed such that a Sperry ball turret could be retrofitted.

Indeed, a number of 5th and 11th Bomb group, and to a lesser degree 19th Bomb Group B-17Es were retro fitted with the ball turret. The scanning windows, and the patch for the sighting bubble for the remote as well as the serial number made it easy to identify the aircraft so fitted.