Bendix Chin Turret

Bendix manual on the Operation and Maintenance of the Bendix Chin Turret for the B-17 Flying Fortress:

Operation of the Bendix Chin Turret


Two Caliber .50 M-2 machine guns.
Ammunition Capacity 450 rounds per gun.

Speed of Turret
Slow speed (tracking) ¼° per second to 12° per second.
High speed (slewing, with high speed button depressed) ¼° per second to 33° per second.

Turret Complete (no guns or ammunition) 438 lbs.
Ammunition 33 lbs. per 100 rounds.
Guns 65 lbs. each.

Gear Drive
Speed Reducer ratio 25-1.
Azimuth gear ratio 50-1.
Elevation gear ratio 42-1.
Azimuth gear train reduction 1250-1.
Elevation gear train reduction 1050-1.

Electrical Requirements
24 Volt D.C.
Peak starting current motor amplidynes 1280 amps.
Maximum current draw running full load 92 amps.
Maximum current draw running no load 40 amps.

Drawing of B-17 Flying Fortress


The Bendix Chin Turret Model “D” is an electrically driven power turret, mounting two caliber, .50 M-2 Machine Guns, equipped with recoil absorbing mechanism, firing solenoids, and manual gun chargers.

The turret is designed to be mounted in the Bombardier’s Compartment and to be operated by the Bombardier to protect the forward approaches to the ship. The guns rotate 172° in azimuth (86° to the left and to the right of forward) and swing from 26° above horizontal to 46° below horizontal. Switch limits are adjustable. The turret is mounted at floor level in the Bombardier’s Compartment. The guns extend below the fuselage at the nose of the ship. The lower assembly, with the exception of the gun barrels which protrude through covered slots, is enclosed in an aluminum, movable housing to minimize wind resistance. Plexiglass windshields seal the space at the floor of the ship around the turret.

B-17 Bomber Chin Turret

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Bombardier Chin and Nose Turrets

From Bombardiers’ Information File, War Department, March 1945:

B-17 Chin Turret and B-24 Nose Turret - Bombardier Turrets

The bombardier is concerned primarily with those gun turrets he is most likely to operate. He is almost always responsible for control of the nose turrets in heavy and very heavy aircraft.


The chin turret of the B-17 operates electrically by remote control from the bombardier’s seat directly above it. It moves 86° to either side in azimuth, 26° above and 46° below horizontal in elevation. It uses the N-8 or N-6A optical gunsight. The bombardier’s seat remains stationary; as he turns the gunsight, the guns swing around beneath. The bombardier’s control unit, housing the gunsight, pivots out from its stowed position on his right and locks in place in front of him.


The nose turret of the B-24 is an all-electric turret which uses the N-8 or N-6A optical gunsight. It moves in azimuth about 75° either side of the airplane’s center line, and in elevation from 50° below horizontal to 60° above. It has 2 speeds, normal tracking and high. It contains armor plate, and bulletproof glass plate which moves with the guns.