Martin ball turret

The Emerson Bow Turret
Emerson 250CE-1

The Emerson Bow Turret, located in the bow position of a number of PB4Y Liberator bombers, can swing u large cone of fire around the whole forward area of the airplane. It is a relative of the Consolidated Tail, and has many points of similarity in design and action. If you are acquainted with the Consolidated, you will feel right at home in the Emerson, though its actual operation is quite different. There is one model—the Emerson 250CE-1.



Facts and Figures

Azimuth limits


The Emerson is all-electric, operating on power supplied by the bomber's central electrical system.

Its sight is the N-6A or N-8 optical, fully described in the Sights and Sighting section of this manual.


The turret moves in azimuth about 75 degrees to either side of the ship's center line.

The turret has two speeds—normal tracking speed and high speed.

Elevation limits

A heavy plate of bulletproof glass, which moves up and down with the guns, helps protect the gunner. Below is a large panel of armor plate, 5/8 inch thick in some places and 3/8 inch in others.

In elevation, the turret guns can be lowered and raised from 50 degrees below the horizontal level to 60 degrees above horizontal.

PB4Y-2 silouette bow turret location

The stowing position is 0 degrees azimuth and 0 degrees elevation—guns pointing directly forward.



Getting In

As you start getting acquainted with the Emerson Bow Turret, remember first of all that it is no place to be hanging around on takeoffs or landings. Quick changes of speed as the bomber leaves or approaches the ground make the turret a dangerous place at those times. On a mission, always get in after the plane is in full flight and get out before the landing. You will have to be careful as you step in. The only way to get in is illustrated here.

Power switch outside turret

Turret doors

First check the power switch mounted outside the turret, on a box which you will find on the fuselage wall just left of the nose wheel. Make sure it is on. (In many planes, the switch is safety wired in the ON position.)
Then open the turret doors and look in to check the switch box on the left rear support. Make sure that all the switches are off—so that the turret cannot move and trap you while you are in the doorway.
After you are sure the switches are off, grasp
the support above the doorway, chin yourself on it, and swing both feet straight into the turret pit. Slide into the seat.
Finally, reach back and close the doors behind
you. Make sure they are securely latched. Then you are ready to operate the turret.

Entering the turretColsing the doors



Operating the Turret

. . Where to Find the Controls
. . How to Use Them

The switch box — now over your left shoulder—holds all the switches to run the turret.

First turn on the master switch, then the azimuth drive switch right beside it. Wait a few seconds, then turn on the elevation drive switch. Just below these three switches is a red plastic cover: under it is the gun switch, which must be turned on next. Then turn on the camera switch, if you need it. Finally, grasp the control handles in front of you, using the bottom edges of your hands to press down the two safety switches (A). The turret won't operate and the sight won't light up unless at least one of these switches is held down. Hold one handle while reaching back to the switch box to turn the sight rheostat to adjust the brilliance of light in the sight. (In some later Emersons, the sight operates independently of the safety switches.)

To operate the turret, simply turn the handles as you would steer a bicycle—to the right to go right, left to go left. Press down on the heels of the handles to raise the guns, and pull up on them to lower the guns. Don't jerk the controls. Move them smoothly. The other controls you will need in combat are right at your fingertips. Right under

Handles and charging levers

your index fingers on both handles are the triggers (B). On top of the right handle next to your thumb is the high speed button (C) that throws the turret into high speed for changing from one target to another.
On top of the left handle next to your thumb is the push-to-talk button (D) that opens the interphone system for you to speak. Near your knees are charging levers (E) for hand charging the guns. To use them, pull them up sharply, then release them and let them drop back by themselves.
The Emerson has fuses to protect some electrical circuits, reset buttons to protect others. Most of them are on the switch box, with spare fuses in the upper left corner. Reset buttons for the azimuth and elevation power circuits are on the junction box outside the turret.



Auxiliary units

Using the Auxiliary Units

For your oxygen mask, you will find a hose connection leading from a demand type regulator (A) mounted on the support framework near your right shoulder. Alongside is a flow and pressure gage (B). Oxygen is supplied from the bomber's central tanks.
The heated suit plug-in (C) is mounted near your right foot on the wall of the turret tub. Jacks (D) for plugging in your earphones and microphone lead out of the column mounting the control handles. The jack box is outside the turret in the bombardier's compartment.
You will find the trouble light (E) and switch on the top left support tubing, and a gun camera bracket (F) to the right of the sight. At the top of the bulletproof glass is an electric heater (G) to keep the glass clear at low temperatures. The mechanism for operating the turret by hand in emergencies includes a foot-firing pedal (H), which permits you to fire the guns while your hands are occupied.
You will find the azimuth hand crank (I) in a bracket near your left knee, and the elevation hand crank (J) near your right knee.

Manual control shift lever

To shift to manual operation:

1 Turn off all switches.
2 Press the manual control index plates on both hand crank brackets outward to their manual positions.
3 Press down the foot trigger firing keys (K) on each electric trigger.



Getting Out

When you are ready to leave the turret, run it to stowing position—guns pointing straight ahead. Then turn off ail switches. Open the doors behind you and step out of the turret. Then close the doors and make sure they are securely latched.
The Emerson has a special feature called the emergency azimuth control, which enables your crew mates to help you out of the turret in case of accident. By pulling on a cable leading out of the turret, they can disengage the azimuth power system. Then, using a hand crank which is kept in a bracket beneath the door, they can move the turret in azimuth by turning a shaft that sticks out of the bottom of the turret. Thus they can get the turret door into position to open it.

Preparing the Turret for Combat

At this point, you have read how to get into the turret, operate it, and get out. With this information, and practice, you could take over in combat. To be a specialist in the Emerson Nose, you will need additional instructions on how to get the sight and guns ready for a mission, and load the ammunition. You will find this information in the following pages.

Sight adjustment

Adjusting the Sight

The Emerson Nose Turret's N-8 or N-6A optical sight is held by five mounting bolts on top of the sight cradle directly in front of you.
To adjust the position of the sight, as may sometimes be necessary in harmonizing it with the guns, the bolt at your extreme right serves as an adjusting bolt for moving the sight sideways to left or right. Loosen all the mounting bolts (A), but do not remove them. Then reach under the cradle, loosen the nut which holds the adjusting bolt (B), and move the bolt right or left with a screwdriver. When you have the sight in position, tighten the adjustment nut and all five bolts. No up or down adjustments can be made.
For full instructions on care of the sight and checking it before and after missions, see the Sights and Sighting section of this manual.



Adjusting the Guns
Gun mouonts in turretAmmunition feed
The guns are mounted in the Emerson to feed from the inside—the right gun from the left, the left gun from the right. Each gun is held in its cradle by a rear mount block and slide, and a front gun mount. The rear mount block, bolted to the rear of the gun, dovetails into the slide in the cradle—simply check to make sure it fits. The front gun mount is a jaw-like affair that snaps over two bearing pins on the gun's adapter, and is locked in place by a gun release handle on the inside of the cradle. This handle, or lever, is safety wired to the gun shield in its up or locked position. Special charging units are mounted on the inside of the guns; their mounting bolts must be safety wired and the cable connections to the units must have cotter pins.
Sticking up from each charging unit is a special

gun safety latch for holding the bolt in its retracted position after charging—push it down before charging, pull it up when ready to fire. Foot-firing mechanisms, mounted on the buffer tubes of the guns, must have their mounting bolts safety wired. For adjusting the guns up, down, or sideways in their cradles, the rear mounts have bolt and screw adjustment assemblies.

Gun safety latch

To make a vertical adjustment, first loosen the lock nut on the bottom adjustment bolt. Then turn the vertical adjustment collar just above
the nut to raise or lower the back of the gun. Tighten and safety wire the lock nut. To make a lateral adjustment, first loosen the lock nut on the lateral adjustment screw, and loosen the screw not over one full turn. Then loosen the nut on the rear mounting bolt and turn the bolt to move the back of the gun from side to side. Tighten the rear mounting bolt nut, then the adjustment screw and lock nut. By means of these adjustments the guns can be centered in their mounts. Turn the vertical adjustment collar and rear trunnion bolt to the centers of their adjustment movements.
Adjusting nuts




Harmonizing the Guns and Sight

There are a number of ways to harmonize the guns and sight of the Emerson Bow Turret. The exact procedure will be defined by the Squadron Gunnery Officer. A handy method is to line up the sight and boresight the guns on some small object such as a tree or chimney, at least 1,000 yards from the plane. First line up the sight on the object selected, moving the turret by hand crank until the dot of the sight is squarely on the object. Don't move the turret after this. Then, using a bore-sight reflector, boresight through each gun barrel while adjusting each gun by its rear mount adjustment collar and bolt assembly until the same spot the sight is sighted on is in the exact center of each gun bore. (A boresight reflector must be used because there isn't enough space in the nose to sight directly through the gun barrels.) Tighten and safety wire the rear mount lock nuts and bolts.

Illustration of gun harmonizing
Another method of harmonizing the Emerson is to bore-sight on a special pattern stand, such as the one illustrated here. Set up the pattern stand level with the guns at least 50 yards from the plane. Center the guns in their mounts. Then line up the sight to center the dot on the sight cross and boresight the guns on the pattern, using the standard technique described in the Sight and Sighting section of this manual. Both methods described here are parallel harmonization.
Boreshight templete



Loading Ammunition

Two ammunition cans, one for each gun, ride outside the turret along the right and left fuselage wall. Chutes carry the ammunition belts from the cans up through the floor of the turret to the guns. Each can is loaded in the standard folded pattern, starting at the corner of the can farthest from the turret, single-link end of the belt first, rounds pointing toward the outside of the plane.
To get each belt to the gun, force it up through its chute, double-link end first, until the first round starts up the vertical section of the chute into the turret.
Inside the turret, you will find a joint in the vertical section of the chutes (A, B). Break the chutes apart at the joints, and with a piece of hooked wire reach down and haul the belt up. For the next step you will need two extra lengths of belt of about 25 rounds to use as feed strips. First, open the latch on the armor plate in front of you and lift the plate up out of the way. Then drop a piece of hooked wire down the upper chutes (D) and pull the feed strips up over the booster sprockets (C) to the guns, double-link end first. Make sure the rounds point forward. Close the armor panel. Finally, connect the bottom of the feed strips (E) to the main ammunition belts. Make sure that the connecting rounds are evenly shoved into the links. Then re-fasten the chutes at the joints. Just before the takeoff open the armor plate panel again and press the double-link end of each belt into each guns' feedway. Close the armor plate panel, and, after hand charging twice, the guns are ready to fire.

Inside of turret




Pre-Flight Routine . . . follow it step by step
1. Make sure the gun bolts are properly assembled, one for left-hand feed in the right gun, the other for right-hand feed in the left gun. Then remove the two plexiglas gun installation panels on each side of the turret door, and install the bolt, barrel, oil buffer, and backplate groups.
2. Try to rock the guns in their cradles to make sure they are securely mounted. Check to make sure the rear mounting bolts are safety wired and the front gun release handles are safety wired to the gun shields in their up position.
3. Check the charging units on the inside of the guns to make sure their mounting bolts are safety wired and cable connections have cotter pins.
4. Check the foot-firing mechanisms on the guns' buffer tubes to make sure they are securely mounted and safety wired.
5. Check harmonization by boresighting the sight and guns on some small object at least 1,000 yards from the plane, or on a pattern stand.
6. While harmonizing the guns, make sure the manual system is working properly.
7. Inspect the electric cables. Make sure all cannon plug connections ere tight and the main switch box is firmly seated. Report any frayed or damaged cables.
8. Check the oxygen connections to make sure they are tight.
9. Inspect the ammunition belts to make sure
the rounds are in good condition and properly belted.
10. Load the ammunition cans and force the belts up through the guide chutes until the first rounds start up the vertical chutes inside the turret.
11. Make sure the external power switch on the outside junction box is on.
12. Open the turret doors. Before entering, make sure all switches are off and the azimuth and elevation clutch levers are in their manual position. Then get into the turret, taking two ammunition feed strips with you.
13. Make sure the dome is clean.
14. Test the foot-firing mechanisms by charging the guns, pressing down the foot-firing keys on the back of each gun, and stepping on the foot-firing pedal. Listen for a click as the firing pins release.
15. Pull the azimuth and elevation clutch levers back into their power position. Then turn on the master switch.
16. Turn on the azimuth drive switch. Wait a few seconds, then turn on the elevation drive switch.
17. With one safety switch held down, turn the sight rheostat to check its operation and adjust the brightness of the sight. Flip the sight filament switch to both positions. If either filament of the sight bulb is burned out, replace the bulb. Make sure the optic head is clean.



18. Still holding the safety switch down, check the booster motors by tilting them toward the guns. The motors should cut on and off sharply, without lag.
19. Flip on the gun switch. Check headspace in the guns. Then pull one trigger at a time, charging the guns each time, to check electric triggers for proper adjustment. Listen for a click as the firing pins release. Either trigger should fire both guns.
20. Run the turret in azimuth and elevation at normal speed, then with the high speed button held down, to check on ease of operation. Make sure the turret runs with either safety switch held down. Check the limit stops to make sure the turret stops about 75 degrees on either side of the center line and about 60 degrees above and 50 degrees below horizontal. Watch for any binding in the up or down movement of the seat, sight, and bulletproof glass. Then stop the turret and check for creep.
21. Put on your oxygen mask, connect it, and test by turning on the direct flow valve. Check the gage to make sure there is proper

pressure in the tanks, as determined by your crew chief. Then close the valve.
22. Plug in your headphones and microphone to test whether your crew mates can hear you and you can hear them.
23. Plug in and test your heated suit and rheostat.
24. Make sure the trouble light works. Pull the light out on its cord to make sure the retractable reel is working properly.
25. Break the two vertical ammunition chutes and pull two feed strips up through the chutes over the booster sprockets to the guns. Connect the feed strips to the ammunition belts in the lower chutes, and close the chutes at the breaks.
26. Turn off all switches, and move the clutches to their manual position. Get out of the turret, and make a last visual check of the turret, inside and out.
27. In flight, press the first rounds into the guns' feedways over the belt holding pawls. Charge the guns on order of the flight commander.

Before Landing
1. Run the turret into its stowing position—guns level and pointing straight forward.
3. Clear the guns by lifting the gun covers and hand charging them twice. Remove all ammunition from the feedways.
3. Shut off all switches and pull the clutches to their manual position.
4. Get out of the turret and close and latch the doors.

1. Clear out all ammunition from the chutes and cans.
2. Field strip the guns.
3. Clean and inspect the gun casing groups, following the procedure outlined under post-flight checks in the Guns section of this manual.
4. Detail strip the parts removed from the guns, cleaning them and making a thorough check on the condition of their parts, as outlined in the Guns section.
5. Report any malfunctions of turret or guns noted on the mission.



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Transcribed and formatted by Thomas Wildenberg for the HyperWar Foundation