Emerson Bow Turret
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 modelthe Emerson 250CE-1.
Facts and Figures
The Emerson is all-electric, operating on power supplied by the bomber's central electrical system.
In elevation, the turret guns can be lowered and raised from 50 degrees below the horizontal level to 60 degrees above horizontal.
The stowing position is 0 degrees azimuth and 0 degrees elevationguns pointing directly forward.
Getting InAs 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.
|Operating the Turret|
. Where to Find the Controls
The switch box now over your left shoulderholds 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.)
operate the turret, simply turn the handles as you would steer a bicycleto
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
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.
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.
To shift to manual operation:
|1 Turn off
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.
When you are ready to leave the turret, run it to stowing
positionguns 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.
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.
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|
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.
|To make a vertical adjustment, first loosen the lock
nut on the bottom adjustment bolt. Then turn the vertical adjustment collar just
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.
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.
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.|Restricted
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.
|Pre-Flight Routine . . . follow it step by step|
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.
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
in the tanks, as determined by your crew chief. Then close the valve.
1. Run the turret into its stowing positionguns 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.