DCS F-18 - Avionic Subsystem

[VBF-12 Gosling]

We have to look at this sometime....!!! It’s a really big thing and I’m going to take it in chunks....

I have referenced each part to its page in the F-18 Aircraft Manual: F-18-ABCD-000 to allow you to read the manual in tiny chunks and slowly get to grips with it. It has a lot of detail straight away and I feel that hinders the reader from getting the overview of teh system. Hence this thread. Hopefully, this gives the overview and the linked pages gives the detail. This does NOT appear to work on mobile platforms (iPad, iPhone etc). Just scroll to the page

Here are the posts on this subject:
A01 - Avionic Systems Overview
A02 - Modes, Controls and Displays
A03 - Digital Display Indicators (DDI)
A04 - DDI Menus
A05 - Electronic Attitude Display Indicator (EADI)
A06 - Advanced Multipurpose Colour Display (AMPCD)
A07 - Head Up Display
A08 - DDI & AMPCD Symbology
A09 - HUD Symbology

A01 - OVERVIEW

The first sentence in the manual says it all really....

2.13 AVIONICS SUBSYSTEM - Reference: F-18-ABCD-000 - Para 2.13 on page 148
The avionics subsystem combines the integration and automation needed for one-man operability with the redundancy required to ensure flight safety and mission success.

So let’s build the system up....

Mission Computers - Reference: F-18-ABCD-000 - Para 2.13.1 on page 148
Two primary mission computers that back each other up as they are interconnected by a databus, called a MUX (Multiplex). It’s probably a 1553 databus. This also connects all the avionic equipment to the computers so that they have the data to present to the pilot.

Mission Computer 1 = Navigation Computer

• Navigation
• LControl/Display Management
• Built-in-Test (BIT) management
• Status Monitoring
• MC2 Backup/li]
  

Mission Computer 2 = Weapon Delivery Computer

• Air-to-Air
• Air-to-Ground
• Tactical Control/Display
• MC1 Backup

Like the hydraulics, the system is split up into multiple channels. Our aircraft has 6:


This image is linked to the Manual.

Each piece of equipment is connected via a channel twice, X and Y, for redundancy.
Each MC is compartmentalised, which is more conceptual than physical. It allows the software to conduct functions without other software routines compromising them. Take a look at the diagram above:

Channel 1 - Equipment

• Armament Control Processor - Stores Management
• Signal Data Computer A
• Comm 1. Radio Control
• Flight Control Computer A
• Flight Control Computer B
• Air Data Computer - Gathers info form the sensors like the Pitot and Static
• AISI - I have yet to find out what this is!!! There appears to be no references to this in the manual...!
• HARM/CLC - Highspeed Anti-Radiation Missile Command Launch Computer

Channel 2 - Equipment

• ATARS - Advanced Tactical Air Reconnaissance System
• ALR-67 - Part of the Radar Warning Receiver (RWR)
• Data Link - To the ship
• Radar
• Inertial Navigation Set - Ring laser gyros
• RWR - Radart Warning Receiver - Part of Electronic Warfare (EW) equipment
• ALE-47 - Chaff and Flare dispenser
• DFIRS - Deployable Flight Incident Recorder System - Deploys on ejection
• FLIR - Forward Looking Infrared Camera
• Comm 2 - Radio
• GPS - Global Positioning System - The US GNSS
• LTD - Laser Detector Tracker/Camera, NFLR - Navigation Forward Looking Infrared

Channel 3 interconnects the two MCs only

Channel 4 - Equipment

• MU - Memory Unit
• MIDS - Multi Information Distribution System - For Radios and TACAN

Channel 5 - Equipment

• Jammer - The ALQ-165 - Airborne Self Protectin Jammer (ASPJ)
• CIT - Conbined Interrogator/Trasponder
• Right DDI - Digital Display Indicator

Channel 6 - Equipment

• Left DDI - Digital Display Indicatior
• DMS - Digital Map System

[VBF-12 Gosling]

A02 - MODES, CONTROLS & DISPAYS

Master Modes - Reference: F-18-ABCD-000 - Para 2.13.2 on page 159
There are three master modes:

• Navigation (default) - Power up, Gear Down, SPIN mode, No other mode, WonW & Throttle above 56 degree angle
• Air-to-Air - A/A Button, A/A Weapon is selected
• Air-to-Ground - A/G Button

Steering Info - Reference: F-18-ABCD-000 - Para 2.13.2.1 on page 159
Sources are: Waypoint or TACAN and ILS, Data Link (Vector and Automatic Carrier Landing)
Steering can be passed to the AFCS for coupled steering.

Controls & Displays - Reference: F-18-ABCD-000 - Para 2.13.3 & 2.13.4 on page 159
These are on the Multipurpose Display Group. Fancy name of the displays including:

• L & R DDI
• Advanced Multipurpose Colour Display - AMPCD
• Digital Map Set
• Head-up Display - HUD
• CSE & HDG switches

and on the Up Front Control (UFC). They converts info from the MCs into symbology for display - Nav, Attack, Aircraft Attitude.

[VBF-12 Gosling]

A03 - DIGITAL DISPLAY INDICARORS (DDI)

Reference: F-18-ABCD-000 - Para 2.13.4.1 on page 159

DDIs
The left and rights screens. Interchangeable - The DDIs function, display and control the same things from either side.
Conventionally the left is for:

• Stores Status
• Built-in Test Status
• Engine Monitoring
• Caution and Advisory Display

The right is used for:

• Radar
• Weapon Video

NVG compatible - three colours (Red, Yellow and Green)
Can select a Monochrome Map or HUD
If blank or erroneous - Cycle its power

Controls - Reference: F-18-ABCD-000 - Para 2.13.4.1.1 to 2.13.4.1.5 on page 160
Brightness selector knob - OFF / NIGHT / AUTO / DAY
- Night = Low brightness
- AUTO = General + auto contrast
- DAY = Full brightness
Brightness Control - Varies brightness
Contrast Control - Varies contrast
Option Select Buttons (OSB) - x 20 (5 per side) - Select displayed options
Fault Indicator - White = Fault

Note: Although named the AMPCD, the third (Centre) display fully functions as a DDI. Anything that can be displayed or controlled on the Left and Right DDI can also be displayed and controlled from the Centre display.

[VBF-12 Gosling]

A04 - DDI MENUS

Reference: F-18-ABCD-000 - Para 2.13.4.2 on page 160

There are two main menu options that lead to all the others menus. They are switched using the bottom centre option select button (OSB). The list below covers the options working clockwise from Top Left OSB including blanks (-).


F-18-ABCD-000 - Fig 2.22 on page 162
This image is linked to the Manual.

• TAC - Tactical
• TOP ROW
• FLIR - Forward Looking Infa=red control
• NFLIR - Night FLIR control
• DL 13 DSPY - Data Link 13 Display - If working]
• HARM DSPLY - If HARM loaded and communicating
• RIGHT SIDE
• -
• -
• SA - Situation Awareness display
• -
• -
• BOTTOM ROW
• -
• EW - Electronic Warfare display
• MENU - Select between TAC and SUPT
• -
• TGT DATA - Info to follow
• LEFT SIDE
• AZ/EL - Azimuth / Elevation]selection - Info to follow
• -
• HUD - HUD option menu
• RDR ATTK - Info to follow
• STORES - Stores display

[li]SUPT - Support[/li]

• TOP ROW
• MIDS - Multifuncttion Information Distribution System status
• BIT - Built In Tests display and control
• - ]
• MUMI - Memory Unit Mission Initialisation display and control
• RIGHT SIDE
• CHKLST - Check List display
• ENG - Engine status display
• -
• -
• FCS - Flight Control System display
• BOTTOM ROW
• UFC BU - Up Front Control Backup
• -
• MENU - Select between TAC and SUPT
• FPAS - Flight Performance Advisory System - Info to follow
• FUEL - Fuel state display
• LEFT SIDE
• ADI - electronic Attitude Display Indicator (EADI) - Standy for HUD
• HSI - Horizontal Situation Indicator display and control
• HMD - Helmet Mounted Display control
• NETS - Digital Communication System Networks (like radio frequencies)
• GPS - Global Positioning System display and control

More to add to this....

[VBF-12 Gosling]

A05 - EADI DISPLAY

Reference: F-18-ABCD-000 - Para 2.13.4.3 on page 163

The electronic Attitude Display Indicator (EADI) is selected from the ADI Option Select Button of the SUPT MENU display of either DDI or the AMPCD.



It provides:

• Airspeed - Top Left
• Rate of Climb or Descent Indicator (RCDI)- Top RIght
• Altitude - Below RCDI - Boxed. Either Barometric or RadAlt (R)
• Roll and Pitch Ladder - with Horizon
• Yaw Indicator - Bottom centre above MENU. The lower box slides beneath the three upper boxes. Rate 1 equates to the lower box being directly beneath one of the outer two boxes depending upon the turn direction.
• ILS Needles - Active when ILS selected. In Yellow of COLOR selected on the ATTK menu
• Information source selection - Standby Attitude Indicator (STBY boxed) or Inertial Navigation System (INS boxed)

Used during HUD failure.

[VBF-12 Gosling]

A06 - ADVANCED MULTIPURPOSE COLOUR DISPLAY (AMPCD)

Reference: F-18-ABCD-000 - Para 2.13.4.6 on page 165

The Advanced Multipurpose Colour Display is a colour version of a DDI with a digital map layer. It can display any format except A/G radar. It is driven from either teh digital map set (DMS) or the left DDI.



It has controls as follows:

• Option Select Buttons x 20
• OFF / BRT - Rotary switch - On and Brightness Control - Brightness control disabled when NITE or when using a colour maps (AUTO)
• NITE / DAY Brightness - Rocker -
• SYMB - Rocker - Up = Symbology narrower, dimmer, sharper / Down = Symbology Wider, Brighter, less sharp
• GAIN - Rocker - Background video brightness
• CONT - Rocker - Contrast 0 to 9 for 5 secs

[VBF-12 Gosling]

A07 - HEAD UP DISPLAY (HUD)

The HUD is the primary flight instruments, weapon status and weapon delivery display. THe HUD receives attack, Nav, situation and steering from the mission computers via the DDI symbol generators. The HUD is electrically connected to the Upfront Controller (UFC) and has its own control unit below the UFC. The HUD is NFLIR capable with a raster image.



HUD controls:

• HUD Symbology Reject -
  
  • Norm = Full
  • REJ 1 = removal of basic information
  • REJ 2 = minimal attack info
  
  [li]HUD Symbology Brightness - ON and Brightness
• HUD Symbology Brightness Selector - DAY / NIGHT = NVG compatible
• HUD Video Control - OFF, VID, W/B = NFLIR to HUD with White hot or Black hot selection
• Black Level Control - Adjusts NFLIR video level
• Balance Control - VID. To SYM - “Stroke’ brightness relative to raster - Symbols
• AOA Indexer Control - Brightness
• Altitude Switch - BARO, RDR - Altidute data source. Barometric or radar altimeter (R)
• Attitude Selector Switch - INS - info from inertial nav ring laser gyros in the Attitude Heading Reference System (AHRS) or embedded INS/GPS (EGI), AUTO - Priority = INS, STBY - info from Standby Attitude indicator to the mission computer.

[VBF-12 Gosling]

A08 - DDI / AMPCD SYMBOLOGY

There are a lot of quite confusing DDI/AMPCD symbols that can appear during various phases of flight and mode. The basics are below:



Generally:

• Pointers - appear around the edge/compass symbology - Various Triangles
• Symbols - appear in their relative position to aircraft heading on the area of DDI/AMPCD. Some key Symbols are:[li]
  
  • Circle with three “bites” out of it + TACAN. This may be land, sea or air (Air Selected on the UFC). If the TACAN is outwside the range of the selected scale it will appear at the edge with a tail opposite.
  • Steering Lines - DASHED LINES
  • CRS Line - SOLID LINE with ARROW HEAD
  • Speeds - either side of the aircraft. TAS left, GSpd right
  • CRS Information - Distance from Course selected (CSEL) line, very useful for holds and approaches. Bearing displayed. Used to set CRS with switch or type into UFC.
  • WPT Information - Brg, Rng, TTG{/li]
    [li]HDG Select - Useful for maintaining approach. Set with switch opposite the CRS switch
  • ADF Circle - If we ever use ADF!!!! Unlikely

[VBF-12 Gosling]

A09 - HUD SYMBOLOGY

I have decided there is too much of this for one post so I will develop both the DDI/AMPCD and HUD symbology posts as twoseparate posts.

Here is the normal HUD display.


Explanations:

• Velocity Vector. Where the aircraftis ACTUALLY going
• Waterline - Where the aircraft is pointing[li]
  [li]Ghost Velocity Vector - Finding out what this is.... Stby
• Command Heading Marker - Finding out what this is.... Stby
• TD Heading Diamond - Actual Bearing to Tgt
• Target Line of Sight Diamond - Symbol over Tgt on the ground as you view it
• Required Groundspeed - Pointer slides left and right and needs to be over the vertical mark to be at the correct speed for the release envelope
• Elevation & Azimuth Deviation Bars - ILS deviation. This example would indicate you are slightly below glide path and slightly left of centre line - relative to the Velocity Vector
• Course Line Arrow & Dots - Finding out about this but I suspect that the dots are “Half Scale Deviation” which is the normal limit to “go around” if exceeded