Difference between revisions of "AJS-37"

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AJS-37 Viggen

AJS37 Viggen is a Swedish cold war era strike aircraft designed by SAAB AB. It is a 90's modernization of the older 60's era jet AJ37 designed to give the aircraft enhanced capabilities in the reconnaissance (S) and strike (A) roles. AJ37 was Sweden's first attempt at a multi-role fighter and while it did not achieve true multi-role capabilities, it could still perform a variety of roles albeit with some limitations.

Because AJ37 did not achieve true multi-role capabilities, several variants of the Viggen were built, these are:

AJ37 - Regular Viggen, capable of strike and limited air to air but lacks reconnaissance capabilities.
SH37 - Spaningsviggen Hav (Recon Viggen Ocean), used for maritime patrol. It was equipped with a different radar (the PS 371/A) which had longer range than the PS 37/A used on the AJ37.
SF37 - Spaningsviggen Foto (Recon Viggen Photo), had a camera in the nose instead of a radar. It was used for optical reconnaissance.
SK37 - Skolviggen (School Viggen), used to train new pilots and was two-seated.
JA37 - Jaktviggen (Hunting Viggen), air to air viggen. Better radar, newer computer, and better air to air missile armament.
AJS37 - A 90's modernization of AJ37 with capabilities to carry newer weapon systems and reconnaissance equipment.

The variant of the Viggen we have in DCS is the AJS37 variant. This is one of the more modern Viggen variants and as a result can carry some relatively smart equipment, such as the BK90 and RB-15F. These were weapons originally intended for the JAS39 Gripen, but due to delays in the JAS39 program, the AJS37 was adapted to carry them as well. In order to carry said weapon systems, modifications to the CK37 flight computer, which was originally designed for the AJ37, needed to be made. The MPE (MultiProcessorEnhet) was added to the CK37 system to increase its computing power, and a data bus was added as well to support increased system communication. Another improvement for the AJS variant was the addition of the TERNAV navigation system. This system uses radar telemetry data and compare it to a prepared terrain map loaded from the AJS37 data cartridge in order to determine your location. The AJS37 saw service in the Swedish air force from 1991 to the early 2000's when the last planes were switched out for JAS39 Gripen.

History

Weapons List

The following is a list of weapons currently implemented for the AJS37 Viggen.

ARAK m/70B unguided rockets (available in AP or HE configurations)
AKAN 30/55 gun pods (30mm)
Sprängbomb 120kg m/71 General purpose bombs (unguided)
Lysbomb 80kg M/71 Illumination bomb
RB-04E Anti-ship Missile
RB-15F Anti-ship Missile
RB-05A Air to ground / air to air missile
RB-75 (AGM65A) Air to ground missile
BK-90 Mjölner stand-off gliding cluster munitions dispenser
RB-24J (AIM-9P) Sidewinder air to air missile
RB-74 (AIM-9L) Sidewinder air to air missile
KB Countermeasures dispender pod
U/22 ECM pod
U/22A ECM / ELINT pod

Systems Overview

Data cartridge

The data cartridge is essentially a miniature handheld computer. It stores mission data and various other important details that the Viggen flight computer (CK37) needs to properly assist the pilot in the mission. The cartridge also functions as a storage unit for some of the Viggen systems. During startup the pilot inserts the cartridge into the data slot behind him to the left and then proceeds to load the data into the CK37 flight computer. In DCS this is done by switching to REFLOLA, IN, entering the code 9099 and pressing LS.

Radio

AJS37 has a two different radio systems: FR22 and FR24.

FR22

FR22 is the primary radio and is located on the forward part of your left sidepanel. It supports VHF (103.000 - 155.975 MHz) and UHF (225.00 – 399.95 MHz), AM and FM. The output is 20W for VHF and 10W for UHF. On the left part of the front panel is also the frequency selector. This shows the currently selected manual frequency and modulation. Pressing the minus (-) button on the FR22 group selector (the number buttons just below the frequency selector) will set the radio to the manually selected frequency.

FR24

FR24 is the backup radio. Its controls are located further back on the left side panel. It only supports VHF AM, has an output of 3W, and only has a fixed set of selectable channels (H,E,F,G).

Radio + SRS

Connecting the AJS37 radio to SRS is fairly easy. Assuming your SRS installation is correct, start SRS and select the radio you want to use (normally the first one). Manually dial the frequency selector in the Viggen to the frequency you want to talk on, and hit the minus (-) key. Now you should be set. Keep in mind that the FR22 needs the main generator to function, so starting the aircraft is required.

Radar

The AJS37 uses the PS 37/A mono-pulse radar. It operates in the X-band and is designed for locating ships. It can be used to locate ground targets as well, but not as effectively.
The radar can operate in three different modes:
A0: Radar is turned off.
A1: Wide range search, dish will sweep from side to side +-61.5 degrees from the x-axis with a search speed of 110 degrees/second.
A2: Narrow range search, dish will sweep from side to side +-32 degrees from the x-axis with a speed of 60 degrees/second.

Passive mode

If the radar is set to passive mode (switch on the middle left side panel) and mode A0 (radar off) it will not emit anything but only listen for enemy jammers. These will show up as lines on the radar panel indicating in which direction the emitter is located.

Terrain avoidance mode

The radar can also be set for terrain avoidance. This is helpful if you are flying at night or in low visibility situations. In terrain avoidance mode the radar will be positioned at 0 degree angle relative to the horizon, looking directly forwards. It will continue to sweep left and right but the only returns will be from terrain on you altitude. Mountains and hills higher than your current altitude will therefore show up as dark areas whilst the light areas are terrain below your altitude.

Navigation fixes

Nothing here yet. Needs fixing.

CK37 Flight Computer

The CK37 flight computer system was first designed for the original AJ37 Viggen back in the 60's. It was later modified with increased processing power for the AJS37 in order to carry newer weapons and pods. The CK37 is accessible for the pilot using the data panel located on the forward right side panel of the cockpit. It consists of a data indicator, a selector dial, in/ut toggle switch, number buttons 0-9, and waypoint buttons.

Selector dial

The selector dial is a wheel that can be toggled in different positions to control which mode the CK37 should operate in.

The available modes are: AKT POS: Present position. This is the only mode that allows you to switch between waypoints.; REFLOLA: Used for inputting coordinates into the navigation system, for waypoints and such.; BANA/GRÄNS:; VIND/RUTA/MÅL:; TID:; TAKT: Used for inputting tactical information into the CK37 system, weapon settings and such.; ID-NR:

Data indicator

The data indicator consists of 6 digits which shows different information depending on which mode the CK37 system currently is in.

AKT POS

The system will display navigation system status information. The first 4 digits cycles between showing the longitude and latitude coordinates of the current positions in degrees and minutes. The 5th and 6th digits tell you if the TERNAV navigation system is operating, it's status, and your current navigation drift.

5'th digit: 0 = TERNAV inoperable; 1 = TERNAV OK, but not sending any outputs. Stand-by mode. Aircraft is on ground or outside the area of TERNAV operation.; 2 = TERNAV OK, mode rough search. System is attempting to orient itself in a particular area.; 3 = TERNAV OK. Fine search. System in a higher resolution mode. Still ascertaining position.; 4 = TERNAV OK and following, but not used. Commonly seen in mode SPA; 5 = TERNAV OK and operating. System sending automatic fixes to the CK37 computer.
6'th digit: Tells you the amount of accumulated drift in km. A value of 0 is therefore good.

REFLOLA

Nothing here yet.

TAKT