1. When the engines are operating, power is generated by four 24 volt, 200 ampere, type P-l generators, one on each engine, with a total capacity of 22.4 kilowatts. The voltage of each generator may be adjusted at the voltage regulator under the flight deck on each side of the centerline.
2. Main battery power is supplied by two 24 volt, 34 ampere-hour batteries wired in parallel.
3. Auxiliary power is supplied by a type C-10 auxiliary generator, with a capacity of 2.0 kilowatts and powered by an independent gasoline engine ("Homelite" unit). This auxiliary generator must be run for starting engines, or, in the case of main generator failure in flight. The auxiliary engine is not supercharged and power generation from the auxiliary unit, therefore, ceases at high altitudes.
4. For ground operation a provision is made for an external (battery cart) connection. Always use battery cart for first starts, where available, or have auxiliary unit in operation. The excessive loads incident to initial start will shorten the life of the main batteries.
NOTE: The battery switches must be left "OFF" when using battery cart.
1. 24 volt D.C. single wire system. Most of the electrical equipment in the airplane is supplied through this system.
2. 26 volt A.C. system for the autosyn indicators.
3. 115 volt A.C. system for the fluorescent lighting and the radio compass. Two independent inverters controlled by a selector switch on the Pilot's Pedestal permit use of either unit.
4. 3 volt A.C. system for compass lighting.
5. Miscellaneous systems for the gun turrets. Automatic Flight Controls and radio.
Fuse Boxes and Circuits: From the various fuse boxes to which the above power is delivered, the following sixteen D.C. and A.C. primary circuits distribute power to the mechanisms.
Fusible links (limiters) are added at the four generators, at the batteries, and at several vital points along the power circuit. These links function much like fuses but are calibrated to withstand higher initial currents.
Of the sixteen primary circuits and power circuit, two are described below. The others are described in connection with the systems they control. For example: the Ignition Circuit is under "Power Plant," etc.
1. Lights and easily accessible switches are located throughout the airplane. There are also five extension lights, as follows:
a. In Bombardier's Compartment.
b. Forward of Station 1.0 left side on A.F.C. mechanism.
c. In Radio Compartment over bomb bay.
d. In lower turret.
e. In tail turret.
2. Fluorescent light, for the Pilot's Compartment only, comes from four lamps in the instrument panel area.
Exterior Lights: There are five circuits of exterior lights controlled by switches in the Pilot's Compartment.
1. Landing Lights — One retractable landing light is located in the bottom surface of each wing.
2. Passing Light — One red passing light is located in the left wing leading edge.
3. Formation Lights — There are seven blue formation lights, three on top of the fuselage and four on the top of the horizontal stabilizer.
4. Running Lights—There are six running lights, one on each wing tip, top and bottom, and one on each vertical fin.
5. Recognition Lights—There is one white light on top of fuselage over center of the wing and three lights (red, green, and amber) under the catwalk.
Panels and Switchboards:
Generator—Main control panel forward face bulkhead at Station 4.1, left side flight deck. Carries four field switches to cut generators in or out of main system: one voltmeter with multi-point selector switch to show voltage output of each generator or main bus, and the four ammeters, showing current flow, each for one generator.
Voltage regulators, two each side forward of bulkhead at Station 4.1 under flight deck, provide for generator voltage adjustment for balance of load.
ive main electric switch panels control the distribution of power to the sixteen primary circuits. One of these is at the left of the Bombardier; the other four are in the Pilot's Compartment.
Spare Fusible Links, Fuses and Lamps: The fusible links for the four main generators are not accessible in flight; neither are the landing light filament circuit fuses.
Fuses and interior fusible links are replaceable in flight and are located as follows:
1. Spare fusible links are located in the limiter boxes which are located as follows: two on left accumulator bracket; four on the left and six on the right rear face bulkhead at Station 4.1. All links require a small wrench to remove and install.
2. Spare fuses are provided in each fuse box.
3. A spare bulb for the landing gear down position indicator is clipped to the instrument panel.
4. A spare bulb assortment is located aft of bulkhead at Station 4.0 on the left side. No bulbs for exterior lights are carried.
All radio equipment used in B-24D Airplanes derives power from the 24V DC supply of the main power system. The radio system includes the following individual systems:
Unit 1 Interphone system
Used for intercommunication between crew members and to provide for reception or transmission of radio messages from any crew station except as noted under "Liaison Equipment" later in this volume.
Unit 1-1 One amplifier mounted immediately behind Co-Pilot.
Unit 2 Command Equipment
Which is normally used for ship to ship communication.
2-1, 2-2, 2-3 2 Transmitters located over wing center section.
2-3, 2-4, 2-5 3 Receivers located over wing center section.
Unit 3 Liaison Equipment (of medium power)
Used for ship to base or ship to ground communication.
Unit 3-1 1 Transmitter on flight deck under Radio Operator's table.
3-2 1 Receiver on flight deck on Radio Operator's table.
Unit 4 Radio Compass Receiver
Used for direction finding and in cross-country navigation.
Unit 4-1 1 Receiver located over wing center section right side.
Unit 5 Marker Beacon
Used in making instrument landings.
Unit 5-1 1 Receiver located in bomb bay at Station 5.0.
Unit 6 Filter System
FL-5C filters Units 6-3 and 6-4 with BC-345 switch box, for Pilot Unit 6-1
and Co-Pilot Unit 6-2, right and left by Pilot's and Co-Pilot's seats.
The interphone system consists of a type BC-347 Interphone Amplifier, one PE-86 Dynamotor, one BC-366 Jack Box for each crew station, and one T-17 Throat Microphone or T-20 Microphone with RC-19-A Microphone Amplifying Equipment for each crew station. Each throat microphone is equipped with either a CD-318 switch cord or a contractor furnished "push-to-talk" switch as the installation requires. Each jack box is equipped with a headset connector cordage, on one end of which is a PL-55 plug for inserting in the jack box, and on the opposite end, a JK-26 jack into which is plugged the crew member's headset. A stowage hook is provided adjacent to each jack box for stowing the cordages and switch when not in use.
The various interphone stations are located as follows:
||Station 0.1 Right Side
| -//- 1-3
||Station 2.1 Left Side Flight Deck
| -//- 1-4
||Station 2.1 Right Side Flight Deck
| -//- 1-5
||Station 3.0 Right Side Flight Deck
| -//- 1-6
||Right Seat Support Member of Turret
| -//- 1-7
||Station 5.0 Right Cross Member of Bulkhead
| -//- 1-8
||Station 6.1 Left Side
| -//- 1-9
||Station 7.1—Right and forward of Gun Doors
| -//- 1-10
||Station 7.1—Left and forward of Gun Doors
| -//- 1-11
||Station 7.5 Left Side
| -//- 1-12
||Station 9.1 Left Side
The Bombardier's, Radio Operator's, Top Gunner's, Bomb Bay, Bottom Gunner's, Two Side Gunner's, Camera, and Tail Gunner's Stations are all equipped with standard interphone station equipment which consists of the following:
One BC-366 Jack Box
One T-17 Throat Microphone
One CD-318 Microphone with "push-to-talk" switch and cordage, Units 7-3 and 7-4.
One headset cordage with PL-55 plug and JK-26 jack.
NOTE: The output of the Pilot's or Co-Pilot's throat microphones is connected to the interphone or radio circuits, through push-button switches, Unit 7-1, 7-2 located on the Pilot's or Co-Pilot's Control Wheels, Page 103. These switches are functionally identical with the push-to-talk switches in the CD-318 cordage, and when depressed, give the same operation.
Since no provision is made to take power for the interphone system from the command equipment, a separate supply is provided and a separate amplifier is used. The amplifier, Unit 1-1, known as Type BC-347, is installed on the side of the Pilot's Compartment, directly aft of the Co-Pilot's seat. (See photo at left.) The dynamotor, Type PE-86, used for interphone power supply, is mounted on the floor alongside the Radio Operator's Table. The interphone system is turned "ON" or "OFF"" by switch (3) of Unit 2-8, Page 111, simultaneously with the Command Transmitter.
Since no provision is made to take power for the interphone system from the command equipment, a separate supply is provided and a separate amplifier is used. The amplifier, Unit 1-1, known as Type BC-347, is installed on the side of the Pilot's Compartment, directly aft of the Co-Pilot's seat. (See photo at left.) The dynamotor, Type PE-86, used for interphone power supply, is mounted on the floor along side the Radio Operator's Table. The interphone system is turned "ON" or "OFF" by switch (3) of Unit 2-8, Page 111, simultaneously with the Command Transmitter.
Interphone System Operation—Each interphone jack box has five positions to which the selector switch may be adjusted along with a manual volume control. From these five selector positions the following may be accomplished: (See photo below, for interphone jack box markings.)
Position 1—"Compass." The audio output of the "Compass Receiver" only will be heard. A limited control of headset volume can be had by manipulation of the volume control. The microphone circuit is inoperative. This position is available at all stations.
Position 2—"Liaison." The liaison receiver output and the side tone of the liaison transmitter will be heard. A limited control of headset volume is possible with operation of the volume control. The microphone, "push-to-talk" switch operates the transmit-receive relay located within the liaison transmitter. The microphone will modulate the liaison transmitter when the microphone switch is closed, and the transmitter is in the "Voice" position.
Voice transmission from the "Liaison" position is available only from the Pilot's, Co-Pilot's and Radio Operator's Interphone Stations.
Position 3—"Command." The command receiver output and the side tone from the command transmitter will he heard. A limited control of headset volume can be had by varying the volume control. The microphone "push-to-talk" switch operates the command send - receive relays which are located in the command receiver rack. The microphone will modulate the command transmitter when the "push-to-talk" switch is closed and the transmitter is in the "Voice" position. This position is available at ALL interphone stations.
Position 4—"Inter." Provides an intercommunication system for use between crew members. The microphone connects to the input of the inter-phone amplifier, and the headphones to the output of this amplifier. The volume control is not effective in this position. This position is available at all interphone stations.
Position 5—"Call." This is an emergency call position in which ALL headphones at ALL boxes are in parallel across the output of the interphone amplifier. If an emergency should arise a crew member may contact any interphone station, even though it might be in use, by switching his jack box to the "Call" position. The microphone of the calling station is connected to the input of the interphone amplifier but leaves all other microphones in their respective positions.
Filter System—The RC-32 filter system includes two BC-345 switch boxes, Page 104.
Units 6-1, 6-2 and two FL-5C filters Units 6-3, 6-4, as shown on this page. The filter is used for separating the voice (giving weather reports, etc.) from the beacon signal. The BC-345 switch permits the selection of beacon signal only, weather reports only, or beacon signal plus weather reports. This action is accomplished by switching to the desired marking: "Range," "Voice," or "Both." These devices are furnished for only Pilot and Co-Pilot.
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