The Sperry ball turret was used on both the B-17 Flying Fortress and the B-24 Liberator as well as the Navy's PB4Y Liberator. The B-17's Sperry was not retractable. The Liberator's ground clearance was minimal and so a hoist was required to lift the turret into the airframe. The Sperry ball turret could spin 360 degrees, making it impractical to store much ammunition outside the turret. Small ammo boxes rested on the top of the turret and the remaining ammo belts were stowed in the already cramped turret by means of an elaborate feed chute system. Click on the graphic below to see this in more detail.


The January 24th, 1944 issue of Life magazine featured the Sperry ball turret in an article on the emerging technology of computing sights.

A ground crewman inspecting the ball
turret on a B-17.

A WW2 era Kelvinator ad

There is no safe place to be on an aluminum plane that is being shot at. This gunner's luck was particularly bad - a direct flak hit through the front panel..
The Death of the Ball Turret Gunner
by Randall Jarrell

From my mother's sleep I fell into the State,
And I hunched in its belly till my wet fur froze.
Six miles from earth, loosed from its dream of life,
I woke to black flak and the nightmare fighters.
When I died they washed me out of the turret with a hose.

Some of the controls the gunner had to operate in the Sperry ball turret.
The large black box in the center is the turret's optical compensating sight.