F-4B/N basic aircraft systems

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Electrical System

The airplane power system consists of two engine-driven generators, an emergency generator and a power distribution system.

Engine-driven generators

Each engine generator provides power to its respective main ac bus. The left and right main buses are separated by the bus tie relay. The generators are toggled from the generator panel switches, shown in the image.

Generator panel

Switch positions:

  • ON: Power is supplied by the selected generator to the circuit, as long as the engine is running at 53% RPM or higher
  • OFF: The generator is turned off and isolated from the system
  • EXT: When external power is available and both generator switches are placed in EXT, power is supplied to the entire system.

If one generator drops off the line, it is isolated from the system and the LH GEN OUT or RH GEN OUT light illuminates, indicating a left or right generator failure. After a few seconds, the bus tie relay closes to allow the remaining generator to power all the systems. On F-4B aircraft, the bus tie relay closes after 5 seconds, while on later F-4B and F-4N aircraft the time is reduced to 3.8 seconds. While the bus tie relay is open, the BUS TIE OPEN light illuminates to indicate the condition.

Emergency generator

In the unlikely event that both generators are inoperative, an emergency generator is provided. The emergency generator provides power to all essential aircraft systems and is powered by a ram air turbine (RAT). The RAT is actuated from the lever found on the left forward cockpit wall and operates at full power at speeds greater than 90 knots.

Safe extension and retraction of the RAT requires sufficient pneumatic pressure, as illustrated in the following table. Not allowing sufficient pressure buildup will result in damaging the RAT.

RAT pressure requirements
Aircraft Extension pressure Retraction pressure
Early F-4B aircraft: 1000psi 2000psi
Late F-4B and F-4N aircraft: 1000psi 200psi

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Hydraulic system

Hydraulic power is supplied by three completely independent systems. They are Power Control System One (PC-1), Power Control System Two (PC-2) and Utility System. The systems have operating pressures of approximately 3000psi and are pressurized any time engines are running.

Three pressure indicators are provided for the hydraulic system, located in the forward cockpit, on the pedestal panel.

Operating pressure is directly tied to engine RPM and reaches normal operating levels at idle engine power. Normal operating pressures are indicated in the table below for all F-4B and F-4N aircraft. When pressure is below 1500psi, the CHK HYD GAUGES light illuminates on the telelight panel along with the MASTER CAUTION light on the forward panel.

Hydraulic system normal operating pressure
System Normal pressure Tolerance (+/-)
PC-1: 300psi 250psi
PC-2: 3000psi 250psi
Utility (powered by PC-1 or both systems): 3000psi 250psi
Utility (powered by PC-2): 2775psi 225psi

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Flight contols

Control surfaces

The control surfaces are hydraulically actuated and receive input from the cockpit controls, trim controls, aileron-rudder interconnect (ARI) and stability augmentation system (SAS). Stabilators control movement of the aircraft around the pitch axis, ailerons and spoilers on both wind control the aircraft roll and the rudder controls yaw. Maximum deflections of the control surfaces are as follows:

Control surface deflections (in degrees)
Surface Max defl. Min defl.
Stabilators: 23 up 9 down
Spoilers/Ailerons: 45/2 up 0/30 down
Rudder: 30 right 30 left

Cockpit controls and feel system

The cockpit controls are located in the forward cockpit and consist of the control stick and rudder pedals. Forward-aft movement of the stick is used to actuate the stabilators to control aircraft pitch. Lateral movement of the stick is utilized to control the ailerons and spoilers. Pedals are used to deflect the rudder.

A feel system is installed in the controls to prevent the pilot from overstressing the aircraft. The feel system limits maximum stick deflection in the forward-aft direction depending on aircraft speed, to prevent the pilot from overloading the aircraft during high G manouevers.

Trim controls

Stabilator and aileron trim are controlled through a hat switch on the control stick, while rudder trim is controlled through a switch in the left console panel, inboard of the throttles. The trim indicators are located forward of the pilot's left console and contain indicators for each of the three trim axes.

Fuel control panel

Aileron-rudder interconnect

The aileron-rudder interconnect (ARI) system is activated when the airplane is in the approach speed range and the aircraft is in the landing configuration. The ARI ties stick deflection to the rudder control so that stick movement moves both the spoilers/ailerons and the rudder to assist the pilot in coordinating the turns during approach without the use of rudder pedals.

The authority of the ARI system is 10 degrees of rudder in either direction with SAS Yaw off and 15 degrees with SAS Yaw on.

Stability augmentation system

The aircraft is equipped with a three-channel stability augmentation system (SAS) for pitch, roll and yaw. Each SAS channel is independently activated through the AFCS panel on the left console. The purpose of the SAS is to improve aircraft stability around the respective axis by detecting inadvertent motions of the aircraft and applying opposite control input. The SAS will not maintain aircraft altitude or attitude, but only serves as a dampener.

Pitch SAS is active when the switch is in the ENGAGE position. It detects movement around the pitch axis and applies opposite stabilator deflection, up to a limit of 0.5 degrees. Deactivation of the pitch channel will illuminate the A/P PITCH TRIM light on the telelight panel.

Roll SAS is active when the switch is in the ENGAGE position and the stick is centered. It tries to dampen roll displacements by applying opposite aileron/spoiler deflection up to 1/4 of maximum deflection.
WARNING: When high angle of attack manouevers are expected to take place, deactivate the roll channel of the SAS. Aileron deflection during high AoA from the SAS manouevers will induce adverse yaw which may lead the aircraft to departure from controlled flight]]

Rudder SAS is active when the switch is in the ENGAGE position and it can command up to 5 degrees of rudder deflection in either direction.

All SAS systems require the Right Main bus to be powered. Additionally, the pitch channel requires a pressure of 500psi or greater in the PC-1 hydraulic system and the roll and yaw channel 500psi or greater in the utility hydraulic system. In the event that pressure is inadequate, the telelight warnings will not illuminate.

Automatic flight control system

The automatic flight control system (AFCS) is initiated from the AFCS panel by moving the AFCS switch to ENGAGE and the aircraft is within the autopilot G limits shown in the following table. The AFCS utilizes the three SAS channels to control aircraft pitch, roll and yaw thus deactivating a channel will also deactivate the respective AFCS control.

For the AFCS to operate, it is also required that SAS pitch is active. The AFCS will deactivate when the aircraft exceeds certain limits. Exceeding +/- 70 degrees of pitch or bank will deactivate the AFCS until the aircraft is again within those limits, as long as the AFCS switch is in the ENGAGED position. Exceeding the G limits shown on the following table will deactivate the AFCS and return the AFCS switch to the OFF position. These will be indicated by illumination of the MASTER CAUTION light on the forward panel and the A/P DISENGAGED light on the telelight panel. The lights are extinguished by pressing the MASTER CAUTION RESET button on the generator panel.

AFCS limits
F-4B G-limits: +3/0 G
F-4N G-limits: +4/-1 G
Pitch limit: +/-70 degrees
Roll limit: +/-70 degrees

Vertical navigation

The AFCS has two vertical navigation modes, which require the Roll channel of SAS and AFCS to be engaged. Pitch hold and Altitude hold.

When the AFCS is active there is a 0.5 second delay from the moment the stick is moved until elevator control is transferred to the pilot.

Pitch hold is always active when the AFCS is engaged. The autopilot will try to trim the aircraft to maintain the current attitude as soon as the stick is centered in its forward-aft axis.

Altitude hold is engaged using the ALT switch. The AFCS records the altitude of the aircraft the moment the switch is engaged and adjust the trim to intercept the selected altitude within 50 feet.

Lateral navigation

The F-4 AFCS comes with two lateral navigation modes:

  • Attitude hold: When engaged, the AFCS will trim the aircraft appropriately to try and maintain the aircraft's attitude in pitch and roll when the stick is centered in each axis. When the plane is within five degrees from level flight the wing leveler will roll it to level flight. This feature can be toggled on and off using the TOGGLE TAIL WHEEL LOCK key command of FSX/P3D. Attitude hold is available when AFCS is ENGAGED and the selected navigation mode is ATT, TACAN, NAV COMP or HDG with the wing leveler disengaged.
  • Heading hold: When the selected navigation mode is set to HDG and the wing leveler feature is active, the autopilot will steer the aircraft to the selected heading on the HSI

Lateral navigation modes are only available when the Roll channel of STAB AUG and AFCS are ENGAGED

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Communication, navigation and identification equipment

Communication radio

Communication and navigation radios

The communication radio can be found in the forward cockpit, right console and rear cockpit, left console. The comm radios come with 18 preset frequencies, labeled 1-17 and G. Preset frequencies can be changed through the ACM.

These precets can be cycled using the COM CHAN knob. There is one additional mode labeled M -for manual-, which allows the operator to input a frequency using the adjustmend knobs.

The radios are activated by turning the UHF COMM knob to the T/R or T/R+G position.

Operation as shown on the photo:

  1. Frequency: Displays the COM radio frequency without the hundreds and mils. If the frequency is 128.975, the indicator will show 2897. In the picture, a frequency of 127.000 is shown.
  2. Manual frequency adjustment knobs:
    • leftmost knob: steps of 1
    • middle knob: steps of 0.1
    • right knob: steps of 0.025
  3. COM CHAN selector: allows cycling of preset frequencies 1-17, G and M modes

Navigation radio

The navigation radio allows for the input of TACAN frequencies to be used for navigation along with the ADI and HSI. For the navigation radio to be active, the power knob needs to be set to:

  • REC: the radio only receives bearing information
  • T/R: the radio receives bearing and distance information

Operation as shown in the picture: 4. Navigation channel indicator 5. Adjustment knobs: the left knob changes the number part, the right one switches between X/Y.

To utilize with FSX VORs, you need to convert the MHz to a TACAN channel using the following information:

  1. TACAN channels start at 17X, which means 108.00MHz
  2. IMPORTANT:There is a break in TACAN channels, at 59Y or 112.25MHz. To continue from there, the next TACAN channel is 70X which stands for 112.30. When you reach 59, keep incrementing the numbers until 70. No frequency exists for the interim numbers.
  3. Each increment of the tacan channel by 1 means an increase in VOR frequency of 0.1
  4. A Y adds 0.05 to the frequency, while an X doesn't change it.

Example: A frequency of 110.25MHz would be found as follows:

  • 110.25-108.00=2.25
  • Since it ends in 0.05 it is a Y channel, therefore we can deduce the last digit to simplify things
  • 2.2 divided by 0.1 equals 22. Therefore the TACAN channel is 17+22=39
  • Our channel is 39Y

Example 2: A frequency of 115.10MHz would be found as follows:

  • 115.10-108.00=7.10
  • The frequency ends in 0, thus it is a X channel
  • 7.10/0.1=71 increments. Thus, it will take us over the break of 59!
  • The 59 limit is 59-17=42 increments over the starting point. Therefore, we need to increment 71-42=29 over 69 to find our frequency.
  • Frequency number would be 69+29=98
  • Final frequency: 98X



The transponder allows you to set the squawk code in the normal FSX environment by using the mode 3/A knobs.

In a TacPack environment, the Mode 4 switch is used to activate the IFF system. When IFF is off, your plane will be considered unidentified. The 3/A numbers are used to identify (left to right):

  • Team ID
  • Sub-team ID
  • Package/Flight ID
  • Aircraft ID number within the flight

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Fuel System

Internal fuel

The aircraft fuel system consists of six fuselage cells numbered 1 to 6 and two internal wing tanks, one in each wing. Additional fuel can be carried externally on the wings and centerline pylon. The centerline pylon can carry a fuel tank with a capacity of 600 gallons, while the underwing external tanks have a maximum capacity of 370 gallons each.

Fuel control panel

The fuselage tank feeding is as follows:

  • Cell 1 is the engine feed tank and is fed from the other tanks as shown below
    • Cell 2 feeds cell 1
    • Cell 4 feeds cell 1
      • Cell 3 feeds cell 4
      • Internal wing tanks feed cell 4
    • Cell 6 feeds cell 1
      • Cell 5 feeds cell 6
      • Internal wing tanks feed cell 6

Internal wing tank can only be transferred when the aircraft is within 75 degrees nose-up or 15 degrees nose-down pitch. If aircraft pitch exceeds these limits, fuel transfer from the wing tanks is stopped and fuselage fuel is used.

Cell 1 319.79 314.00
Cell 2 225.07 221.00
Cell 3 167.02 164.00
Cell 4 225.07 221.00
Cell 5 204.72 201.00
Cell 6 239.33 235.00
Internal wing tanks (each) 319.00 315.00
TOTALS 1620.33 1591.00

External fuel

In order to use the fuel carried in the external tanks, the EXT TRANSFER switch located on the fuel control panel must be placed in the OUTBD position for the external wing tanks, or CENTER for the external centerline tank. The gear handle needs to be locked in the up position or the WING TRANS PRESS switch be moved to EMERG for the fuel transfer to begin.

CAUTION:There is a difference in the fuel burn sequence between the F-4B and F-4N. When the EXT TRANSFER switch is in either external tank mode, both aircraft will consume fuel from the external tanks. When all the fuel are consumed:

  • The F-4B will consume fuel from the fuselage cells
  • The F-4N will consume fuel from the internal wing tanks and when exhausted will continue to the fuselage cells

Internal wing tank in the F-4B is consumed only when the EXT TRANSFER switch is in the OFF position.

Internal wing fuel dump

Fuel dump is initiating by moving the hexagonal switch labeled INT WING FUEL DUMP to the DUMP position. Internal wing fuel is dumped through nozzles located on the wings, inboard of the wing fold position.

Fuel dump rate is a function of engine RPM, aircraft attitude and acceleration. Fuel dump rate at 85% RPM in straight and level flight is approximately 100gpm, but will increase with pitch or higher RPM.

CAUTION: If the fuel dump switch is in the DUMP position during takeoff or carrier launch, wing tank fuel will be dumped due to the high acceleration. Ensure that the dump switch is in the NORMAL position.

Smoke abatement switch

In the late F-4B and F-4N aircraft, setting the smoke abatement switch in the ON position will produce a less visible trail of smoke from the engines.

Fuel quantity indicator

F-4 fuel quantity indicator

The fuel quantity indicator is split into two sections, indicating available fuel weight in pounds:

  • The sector portion: located in the upper half of the instrument, the sector portion indicates total fuel available in the fuselage cells of the aircraft. Readouts are multiplied by 1000. The sector portion has a tolerance of +/-150 pounds depending on aircraft attitude and acceleration.
  • The counter portion: occupies the lower half of the instrument, it indicates the total internal fuel available (fuselage cells and internal wing tanks). Readouts are multiplied by 10. The counter portion has a tolerance of +/-200 pounds depending on aircraft attitude and acceleration.

To the right of the instrument is the spring-loaded Feed Tank Check switch. When the switch is positioned to CHECK, the instrument indicates fuel quantity in the feed tank (Cell 1).

Note: Due to the instrument tolerances, if a FUEL LEVEL LOW LIGHT illuminates above an indicated 2080 pounds, the warning light should be used as the primary indication of a low fuel state and continued aircraft operation should be judiciously considered.

Fuel level low light

The FUEL LEVEL LOW warning light illuminates when the combined usable fuel quantity in cells 1 and 2 is reduced to approximately 1880 +/-200 lbs or less. The threshold is accurate only when the plane is in a straight and level, non accelerating flight.

Left and right external fuel lights

The L EXT FUEL or R EXT FUEL indicator lights on the telelight panel indicate:

  • an empty left or right outboard external fuel tank, or a multiple ejector rack with the external transfer switch set to OUTBD
  • a full left or right outboard external fuel tank during a refuelling operation

The lights are accompanied by the MASTER CAUTION light in early F-4B aircraft.

Centerline external tank fuel light

The CTR EXT FUEL indicator light is provided to indicate:

  • an empty centerline tank with CENTER selected on the external transfer switch
  • a fully loaded centerline tank during a refuelling operation

The light is accompanied by the MASTER CAUTION light in early F-4B aircraft.

Inflight refueling

The refueling probe is extended by moving the REFUEL PROBE switch in the EXTEND or REFUEL position.When the switch is set to EXTEND and the probe is fully extended, fuselage cells 1 through 4 can be refuelled. When the switch is set to REFUEL, the REFUEL READY light illuminates and refuelling of all tanks is possible depending on setting of the guarded REFUEL SELECTION switch. With the REFUEL SELECTION switch set to INT ONLY, fuselage cells are refuelled followed by the internal wing tanks. With the REFUEL SELECTION switch set to ALL, after all internal tanks are fully fuelled the external tanks begin refuelling.

When the refueling probe is not locked in the retracted position, the IFR PROBE UNLOCKED light illuminates.

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Pneumatic system

The pneumatic system provides high pressure air for the normal and emergency operation of:
F-4 pneumatic pressure indicator
  • canopies
  • ram air turbine
  • nosegear extension

Air is drawn from the engine bleed air supply and compressed to 3100, +100, -50psi. Pneumatic pressure is indicated in the pneumatic pressure indicator, located in the forward cockpit. The instrument has a range of 0 to 5000 psi with calibrations of 0 to 50 and reads multiplied by 100.

Normal operation of the system is automatic while engines are running. Normal indications are 2680 to 3270psi.

Canopy operation

Canopies can be operated in two ways:

  • normal operation
  • manual operation

For normal operation, both cockpits are equipped with a paddle switch. This paddle switch is located to the left, to the middle and under the canopy sill for the pilot and RIO. The paddle switch utilizes pneumatic pressure from a bottle to cycle the canopies. The bottle is recharged from the aircraft's pneumatic system as long as pneumatic pressure is available. When there is no pneumatic pressure available, the paddle switch can still be utilized to operate the canopies. However, because the bottle cannot be recharged the bottle will be expended within 4-6 canopy cycles, requiring manual operation after that.

Manual canopy operation is done in both cockpits by:

  1. Use the manual canopy unlock lever, located on the right wall. When the lever is back, the canopy is unlocked and can be moved. When the lever is forward, the locking mechanism closes and the canopy is secured in place.
  2. moving the canopy with the hands (click on the canopy frame to raise/lower it)

When the canopy is unlocked, the CANOPY light will illuminate on the telelight panel.

CAUTION: Opening the canopy or leaving it unlocked at speeds above 50 knots will result in the canopy being separated from the airplane.

Canopy jettison

Canopy jettison is initiated in both cockpits by pulling the yellow lever found on the left wall.

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Interior lights

There are two interior light panels, one in the forward cockpit and one in the rear. For the forward cockpit panel:

  • INSTR PANEL knob: controls brightness of main panel instruments
  • CONSOLE knob: adjusts brightness of floodlights and console backlighting in forward cockpit
  • CONSOLE FLOODS switch: Three settings for floodlights, that limit the max intensity. DIM, MED and BRT
  • STBY COMP: Toggles lighting of the whiskey compass
  • TEST switch: This is switch is spring loaded to the OFF position. When held to TEST the telelight panel will illuminate
  • IFR switch: toggles the refueling probe light. The IFR light illuminates the tip of the refueling probe to facilitate night time inflight refueling.
  • INDEXER LIGHT knob: controls the intensity of the angle of attack indexer lights, mounted at the front canopy. The angle of attack indexer lights are on only when the landing gear is extended.

In the early F-4B aircraft, the lighting panel is located in front of the RIO, above the instruments. In late F-4B and F-4N aircraft it is located to the left, in front of the radios.

  • EQUIP LIGHTS knob: adjusts the intensity of the flood lights and backlighting of the consoles
  • INSTR LIGHTS knob: adjusts the intensity of instrument backlighting
  • COCKPIT FLOODS switch: limits the maximum intensity of the rear cockpit floodlights
  • WARN LIGHTS: This is switch is spring loaded to the OFF position. When held to TEST the rear cockpit warning lights will illuminate
  • NAV COMP switch:
    • Up: BDHI needle No.1 will indicate bearing to the selected ADF station and No.2 bearing to the selected TACAN station
    • Down: Relays TARGET or BASE coordinates to the BDHI, depending on INS setting. Needle No.1 will indicate bearing and No.2 will indicate track to the selected waypoint.

Exterior lights

Exterior lights panel

The exterior lights panel is located on the forward cockpit and controls the aircraft external lights.

  • TAXI LT: toggles the landing light
  • FUS switch: Controls the fuselage lights located under the intakes and forward tail light.
  • WING switch: Controls the wing tip lights
  • Flasher switch: Controls whether WING and FUS lights will illuminate steadily or flash
  • TAIL switch: INOP on navy aircraft
  • Hook BYPASS switch: controls the angle of roll light located on the fuselage, above the trailing edge of the left wing
    • NORM: The AOR light will illuminate steady when Gear and Hook are down, flaps 1/2 or full. If hook is in transit, gear down and flaps 1/2 or full, the AOR light will illuminate
    • BYPASS: The AOR light will illuminate only when Gear and Hook are down, flaps 1/2 or full.

Oxygen system

The oxygen system provides pilots with breathable oxygen. It is toggled through the flip-over switch on the oxygen panel, located on the left console in both cockpits. While correct duration of oxygen has been simulated, no adverse effects due to lack of it are simulated. The table below shows oxygen duration for one crew member using the supply. If two members use oxygen, duration is halved.

Oxygen duration (hours)
Cabin pressure altitude Gauge quantity - Liters
10 8 6 4 2 1 Below 1
40,000 and above 60.6 48.5 36.4 24.2 12.0 6.0 -EMERGENCY-
35,000 37.0 29.6 22.2 14.8 7.4 3.6
30,000 27.2 21.8 16.4 10.8 5.4 2.8
25,000 20.4 16.4 12.4 8.2 4.0 2.0
20,000 16.0 12.8 9.6 6.4 3.2 1.6
15,000 12.8 10.2 7.6 5.2 2.6 1.2
10,000 10.0 8.0 6.0 4.0 2.0 1.0
5,000 8.4 6.6 5.0 3.2 1.6 0.8
Sea level 7.0 5.6 4.2 2.8 1.4 0.6

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