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U.S.S. LITTLE ROCK CLG-4 / CG-4

6
"/47 Mark 16 Gun

(Updated 29 Feb 2012)



CLG4 Fires 6" Gun
USS Little Rock CLG 4 fires her 6"/47 guns during exercises off the coast
of Sardinia, Italy on 23 April 1975.
Official US Navy Photo.


6" Fires to Port

6" Fires to Starboard
U.S.S. Little Rock's
6"/47 Guns Fire to Port

(Photo courtesy of Paul Jett)

U.S.S. Little Rock's
6"/47 Guns Fire to Starboard

(Cruise Book Photo)


GENERAL INFORMATION

6"/47  Mark 16

The 6"/47  Mark 16 guns were used to arm both Brooklyn and Cleveland class light cruisers. Developed from experiments with old 6"/50 Mark 8 gun, this weapon was capable of using the "super heavy" AP projectile which had almost double the penetration of the previous 6"/53 gun used on the Omaha class light cruisers.

These guns were constructed with monobloc autofretted barrels secured to their housing by a bayonet joint.  Later mods included chrome plating and a tapered liner.  All 6"/47 guns used a semi-automatic vertical sliding breech block.

Each 6"/47 gun was supplied by its own projectile and cartridge hoists.  The cartridge hoist was an endless conveyor type with open flights rather than powder cars. Projectiles and cartridges were rammed together.

Each turret required a crew of 3 officers and 52 enlisted men.




The following is extracted from:

NAVAL ORDNANCE AND GUNNERY, VOLUME  1, CHAPTER 7 "TURRET INSTALLATIONS"

7F. "Turrets Equipped With Case Guns",

7F1.
(See Reference link below.)

7F2. Six-inch 47-caliber triple-gun turrets

Light cruisers of the Brooklyn, Cleveland, and Fargo classes are equipped with single-purpose 6-inch turrets of similar designs. The gun has a monobloc, radially expanded barrel with housing and wedge-type sliding breechblock. Ammunition is supplied to the gun room through 1 projectile hoist and 1 powder hoist for each gun, and is transferred by the gun crew from the top of the hoist into a loading tray in the gun slide. Although the maximum elevation of the guns is 60 degrees, loading must be accomplished at an elevation of 22° or less because of the limitations of the ammunition-loading mechanisms and the empty-case ejection system. Gun compartment features generally resemble the smaller semiautomatic guns, such as the 5”/38.

The gun compartment is not divided into separate gun rooms, because the inherently greater safety of case ammunition renders such minute flametight subdivision unnecessary. The rear part of the gun house, as in major-caliber turrets, includes the turret officer’s booth with rangefinder and equipment for local control of fire. The pointer’s and sight checker’s stations are located outboard of the left gun, the trainer’s and sight setter’s stations outboard of the right gun, neither station being separated from the gun compartment by bulkheads.

Levels of the turret below the gun compartment serve the same purposes as in the 16”/50 turret. They are somewhat simplified as appropriate to the smaller size and lighter weight of the whole assembly and each of its components. One major simplification is in powder hoist design, the charges for the 6”/47 gun being handled by an endless-chain conveyor-type hoist with open flights instead of powder cars. Elevating and training gear are of electric-hydraulic type and permit a selection of remote or local control.

7F3
. (See Reference link below.)




The following is extracted from:

NAVAL ORDNANCE AND GUNNERY, VOLUME  1, CHAPTER 7 "TURRET INSTALLATIONS",



7G. " 6”/47 Dual - Purpose Gun and Turret "

7G1 thru 7G6.
(See Reference link below.)

7G7. Fire control and power drive equipment

The 6”/47 dual-purpose turret is designed to deal with air as well as surface targets. It is capable of a maximum surface range of over 25,000 yards, and can reach targets at an altitude of over 51,000 feet when at its maximum elevation of 78°. There is no optical rangefinder in these turrets, but they are equipped with telescopic prismatic sights, periscopes, and sight-setting equipment, as well as radar and computer equipment.

The turret is driven in train and the guns in elevation by electric-hydraulic power drives controlled by receiver-regulators. The fuze setters on the gun slides are also operated by receiver-regulators. There are six designated types of turret control:

     1. Primary surface control. The gun and turret drives are controlled by an aloft radar antenna mount or by an aloft main-battery gun director, operating in conjunction with main-battery plotting room equipment. This control has two variations: “AUTOMATIC” and “INDICATING.”

     2. Primary AA control. The gun and turret drives are controlled by an aloft main-battery gun director operating in conjunction with main-battery plotting-room equipment. This control has two variations: “AUTOMATIC” and “INDICATING.”

     3. Secondary surface or AA control. The gun and turret drives are controlled by a 3-inch battery director.

     4. Local radar control. The drives are controlled by the radar equipment within the turret. In this method of control, the pointers control gun laying with their sights and handwheel controls: Turret train is controlled by the radar operators using the train transmitter (turret order) to send gun train orders to the receiver-regulator and to the gun train indicators.

     5. Hand control. The gun-laying and training drives are controlled by the pointers and selected trainer using their sights and handwheel controls.

In primary surface or AA control, the turrets and their guns are controlled, in automatic control, by signals received from the controlling plotting room. Or they may be controlled and positioned in the follow-the-pointer operation, called indicating control. Either selection can be controlled from the forward or after plotting room, using any one of the aloft radar antenna mounts or main-battery directors for surface control, or using any one of the main-battery directors for AA control.

In secondary surface or AA control, the turret drive may be controlled by similar automatic and follow-the-pointer (indicating) control variations from a selected secondary (3-inch battery) director.

Turret local control methods include local radar control, hand (target-sighting) control, periscope control, and combinations of these. All of these methods use the local computer for solution of the firing problem for the proper sight angle and sight deflection for hitting the target. The computer operator gives the computed values of sight angle and sight deflection to the sight setters. The sight setters crank these quantities into their indicators to set the sights to the ordered values of sight angle and deflection.

Radar control arrangements are one of the feature innovations of the turret. The installation includes one complete radar control set in the turret officer’s booth, a radar antenna, and antenna train drive. This installation enables the turret to ascertain target direction, distance, course, and speed. It is a range-finding system that completely displaces the optical range-finder of earlier turret design, and provides new alternative methods for local control. The radar signal beam to the target can be employed to yield line-of-sight and range data.

Unlike other 6-inch turrets, the elevating gear is of the arc and pinion type (same principle as the 5”/38 mount) instead of the screw and nut type (like that in the 16”/50 turret).

7G8 and 7G9
(See Reference link below.)

 
THE 6"/47 GUN USED ON THE U.S.S. LITTLE ROCK
NAVAL GUN TERMINOLOGY and DEFINITIONS

For interested non-Gunnersmates  CLICK HERE to go to a short list of terms and definitions used in Naval Gun discussions and literature.
REFERENCE LINKS

NAVAL ORDNANCE AND GUNNERY MANUAL
(Provided by Gene L. Slover)

NavWeaps.com Naval Gun Page

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