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Saab 37 Viggen

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Re: Saab 37 Viggen

Postby Octal450 » Thu Sep 10, 2020 10:04 pm

Fantastic thank you Colin

Kind Regard
Skillset: JSBsim, Systems, Canvas, Autoflight/Control Systems, Basic Animations
Aircraft: MD-11 (Mainly), A320-family, MD-80, Contribs in a few others

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Re: Saab 37 Viggen

Postby colin_geniet » Sat Jan 09, 2021 6:07 pm

Version 5.0.0 has been pushed to FGAddon, and this is a very big update, if I may say so myself!
Here's the list of major changes. See below for details.
  • Added a flight manual
  • Removed the AJ 37 variant
  • Reworked the front instrument panel
  • Rework of the HUD and MI display for the JA variant
  • Completely new HUD for the AJS variant
  • Added main mode selector knob to the AJS variant
  • Added an IFF system, and for the JA variant a fighter link
  • New MP damage system, using the Emesary notification framework
  • Significant changes to fire control systems
Complete list of changes is here: ... ngelog.txt

Minimum supported FG version is now 2020.3.1

Flight Manual
At long last there is a flight manual, created with the help of Rick Gruber-Riemer!
You can find it in the aircraft directory under 'JA37/Doc/', or here: ... t/JA37/Doc. In simulator, the menu 'JA 37 > Manual' can be used to open it. Should anyone be interested, source code is here: ... umentation
The manual is very far from complete, but should already contain some useful information, notably regarding the new changes. In particular you should refer to it regarding the new AJS HUD, and the changes to controls and keybindings.

The HUD has been rewritten for both the JA and the AJS.
The JA HUD hasn't changed much (the previous one was already very accurate), except for combat-related stuff - more details below.
On the other hand, the AJS HUD is completely new, and quite different from the JA HUD. I very strongly recommend checking the dedicated chapter in the manual, since the AJS HUD is nothing like the usuals modern HUDs, and it is not easy to figure out what is displayed.

AJS main mode selector knob
This is one of the most important knobs on the AJS! It is on the radar control panel, just next to the throttle. It selects the aircraft mode, among Self test, Standby, Navigation, Combat, Reconnaissance, Instruments landing, and Optical landing. (test and reconnaissance being unimplemented). Keybindings 'm/M' can be used to rotate the knob.
The keybindings 'Y' (landing mode) and 'h' (combat mode) have been removed.

New MI display
The MI (radar screen for the JA variant) has been reworked. It is now a B-scope (shows azimuth and range of radar echoes). Symbology has been improved based on photos and pictures of the real MI.
Controls have also changed a bit: keybinding 'n' (cycle radar echoes) has been removed, as it is particularly unrealistic. Tracking a radar echo is done by moving the MI cursor onto that echo, and clicking.
There are a number of ways to control the cursor:
  • Add joystick keybindings, either through the GUI, or by binding properties '/controls/displays/cursor-{slew-x,slew-y,click}'
  • Press 'y' to control the cursor with flight controls, press 'l' to click. Pressing the trigger to click no longer works
  • [NEW] Enable the option 'arrow keys control cursor' in the Viggen options dialog, and use arrow keys to move the cursor, 'enter' to click.
See the manual for more details.

Regarding the AJS radar
It is no longer possible to lock onto a target with the radar - this is just no how the AJS radar works. And the new AJS HUD won't display any such thing, so locking on a target would be next to useless anyway. The AJS radar still works: it shows the bearing and range of any radar echo in range. But it's up to you to make use of this information (admittedly, it is currently very underwhelming, and I hope to improve it soon).

IFF allows allied aircrafts to recognize each other. The control panel is on the rear right panel. There's a power knob (OFF/AUTO/ON), and a channel selector knob (it goes up to 11!).
An aircraft tracked on radar will be recognized as friendly if its IFF is on and set to the same channel as yours. It will then be displayed with a cross on the MI and the HUD, and in green on the TI (anything else is red). In addition, ctrl-F will interrogate the contact under the MI cursor, and display a cross over it on the MI if it is friendly. The dialog 'Friends (IFF)' works as a whitelist for IFF: any callsign entered will be reported as friendly, regardless of IFF code.
The AJS variant only has the transponder part of the IFF system (it can be identified by others, but not identify them).

Fighter Link
Fighter link allows to share data between aircrafts in a same flight, e.g. their position, or the position of tracked radar contacts. Together with fighter control (similar, but between aircraft and ground command center), it was one of the most innovative features of the Viggen fighter variant.
Fighter link is turned on with the SYST>DL menu on the TI display (HSD). When it is on, the small 'DL' box on the lower left of the TI is green. The fighter link channel selector is just in front of the comm radio. To input a channel, press 'DEL' (clears the field), then use the comm radio numpad to enter the channel.
Viggens on the same fighter link channel will share their own position, and the position of any radar contact they are tracking. All of this is then displayed on the TI display.
However, the TI display no longer shows all radar echoes in range (only the tracked one), as this was quite unrealistic, and somewhat defeats the point of fighter link.

Multiplayer damage using Emesary
This is a completely new multiplayer damage system, developed by Nikolai V. Chr. and Richard Harrison using the Emesary notifications multiplayer bridge.
What it means in practice:
  • The automated chat messages are completely gone. Civilian pilots will enjoy not being annoyed by these messages (particularly from the less polite of fighter pilots, ahem). Military pilots will enjoy the added realism.
  • Some new features have also been added: flares, missile trails, ejection seats are displayed over MP, and missile warnings are received on the RWR. Of course, this is only enabled if both sides toggle MP damage on.
  • Finally, all of this is completely incompatible with the old MP chat damage system.
Please note that it requires FG 2020.3.1 or later to work

Fire Control Systems
Weapon controls have changed significantly.
  • There is now a trigger safety. Its role is complex, as it also arms the selected weapon when moved to the unsafe position. Because of this, proper use of trigger safety is not obvious, and is required to use weapons.
    The general procedure is
    1. Select the desired weapon, and enter combat mode if desired.
    2. Only after that open the trigger safety (shift-E), normally once the target is in sight/on radar, and you have decided to shoot.
    3. Fire. For missiles, fire only one weapon - the next ones won't work anyway.
    4. Secure the trigger, repeat procedure if necessary.
    See the manual (last chapter) for more details.
  • Master arm is gone - there is no such thing in the Viggen
  • Combat mode (which used to be controlled by master arm) is no longer required to use weapons. It still exists, but only to provide additional aiming information. In the JA 37, combat mode is enabled with 'h' (which used to be master arm). In the AJS 37, it is enabled with the main mode selector knob (see above).
  • Some keybindings (e.g. for weapon selection) have changed, see the in-simulator help menu, or the manual.
  • For the AJS 37 only: since it is no longer possible to lock on a radar contact (see above), all weapons have been adapted to allow firing them without lock. Most weapons now have realistic behaviors; a few, not quite so...
    • For IR A/A missiles (sidewinders): the seeker head is locked straight ahead. You must lock by steering the aircraft towards the target. Once a lock is obtained (sidewinder sound changes), you can uncage the seeker with 'U' to allow it to follow the target. Press and hold 'U' to reset the seeker.
    • For the Rb 04 and Rb 15 A/S missiles, and the m/90: just fire them towards the target, and they will lock on the first thing they find (for the Rb 04 and Rb 15, this is mostly accurate, although the target search logic should be far more complicated. For the m/90, this is complete nonsense since it should use inertial guidance towards a preset target waypoint).
    • For the Rb 75 Maverick: the seeker position is displayed on the HUD as a small circle. It is manually controlled using the cursor controls (see above in the MI display section). Once it is over the target, click to lock on the target.
      (In the real Viggen, the small EP-13 screen is used instead to display the Rb 75 TV seeker image. Other than that, the controls are somewhat accurate).

Read the manual, enjoy your flight, and report the bugs!
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Re: Saab 37 Viggen

Postby Johan G » Sat Jan 09, 2021 9:42 pm

I highly recommend trying out this aircraft, it is quite fun to fly.
Low-level flying — It's all fun and games till someone looses an engine. (Paraphrased from a YouTube video)
Improving the Dassault Mirage F1 (Wiki, Forum, GitLab. Work in slow progress)
Johan G
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