Original Item: Only One Available. This is a very nice example of a mechanical Ball Turret Position Azimuth Position Indicator, manufactured by SPERTI, INC. of CINCINNATI, O. US.A..  It is marked with PART NO. 11585, and was used in the Sperry ball turret in WWII heavy bombers such as the B-17 Flying Fortress and B-24 Liberator. 

This indicator would be mounted within the ball turret at the right foot of the ball turret gunner, and was connected to a rotating mechanical control cable. The round turret silhouette in the center of the dial rotated as the turret rotated relative to the forward direction of the aircraft. Thus, should the ball turret gunner hear "bandit at 4 o'clock low", he would know to rotate the turret to that position on the dial in order to greet the incoming foe with 50 cal welcoming gifts. The field of view of the ball turret gunner was actually quite poor and it wasn't difficult for the gunner to lose orientation with respect to the direction of the aircraft.

The condition of this example is very good, with the expected wear to the external finish from being over 70 years of age. Ready to add to your WWII Bomber Collection!

More on the Boeing B-17 "Flying Fortress" Bomber
On July 28, 1935, a four-engine plane took off from Boeing Field in south Seattle on its first flight. Rolling out of the Boeing hangar, it was simply known as the Model 299. Seattle Times reporter Richard Smith dubbed the new plane, with its many machine-gun mounts, the "Flying Fortress," a name that Boeing quickly adopted and trademarked. The U.S. Army Air Corps designated the plane as the B-17.

In response to the Army's request for a large, multiengine bomber, the prototype, financed entirely by Boeing, went from design board to flight test in less than 12 months.

The B-17 was a low-wing monoplane that combined aerodynamic features of the XB-15 giant bomber, still in the design stage, and the Model 247 transport. The B-17 was the first Boeing military aircraft with a flight deck instead of an open cockpit and was armed with bombs and five .30-caliber machine guns mounted in clear "blisters."

The first B-17s saw combat in 1941, when the British Royal Air Force took delivery of several B-17s for high-altitude missions. As World War II intensified, the bombers needed additional armament and armor.

The B-17E, the first mass-produced model Flying Fortress, carried nine machine guns and a 4,000-pound bomb load. It was several tons heavier than the prototypes and bristled with armament. It was the first Boeing airplane with the distinctive - and enormous - tail for improved control and stability during high-altitude bombing. Each version was more heavily armed.

In the Pacific, the planes earned a deadly reputation with the Japanese, who dubbed them "four-engine fighters." The Fortresses were also legendary for their ability to stay in the air after taking brutal poundings.

Seventy-five years after the B-17's first flight, an 88 year-old veteran sent The Boeing Company a letter. After explaining how he returned to England after a bombing raid over Germany with 179 flak holes and only two out of the four engines, he wrote: "I'm glad to be alive. Thank you for making such a good airplane."

Gen. Carl Spaatz, the American air commander in Europe, said, "Without the B-17 we may have lost the war."