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  Tank Fire Control Systems (v 0.2)  
Picture of Tank Fire Control Systems Author : NonWonderDog
Version : 0.2 Era : Modern Type : Misc
Size : 1,91 MB Demo mission : No
Downloads : 4441 Rating : 3 / 5 (rated 1 time)

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Included *.pbo files : Needed addons :
  • NWD_Rangefinder.pbo
  • NWD_TankBallistics.pbo
  • NWD_TankLoadout.pbo
  • NWD_TankModels.pbo
Description :
This mod replaces just about everything that has anything to do with firing the guns on a tank.

First off, shell damage and trajectories are changed to be more in line with reality (APFSDS rounds will travel 100km+ in real life!;), and the coaxial machineguns fire at their real cyclic rate.

That's not why you want it, though. In addition to changing the ballistic properties of the shells, this mod adds a simulation of the real fire control computers of both the T-72M and the M1A1 Abrams. The fire control works nearly exactly as it does in the real tanks (with a couple caveats), down to the smallest details I could find.

As of now, only the highest zoom level of the main gun sight is simulated properly. I intend to add night sights, multiple magnification levels, and commanders' sights later.

This also includes a bug-fixed version of my GLTD II rangefinder mod, described here. They share a lot of the same code, so this cuts down on a bit of processor time versus having them both running separately.

Gunnery Manual

M1A1 Gunnery
Getting a fire solution in the M1A1 Abrams is easy once you know what you're doing. To hit a stationary target with the main gun, all you need to do is make sure you have the proper ammunition type selected (select "Change FCS Mode" in the action menu if not), place the target within the 1-mil circle of the reticle, lase the target, and fire. Firing with the coaxial is carried out identically, just switch to the coaxial machine gun, lase the target, and fire. If you are engaging with both weapons, you only have to lase the target once; the fire control system will apply the proper corrections automatically when you switch weapons. If the target you have lased is outside the programmed maximum range of the selected weapon, the range display will flash and the gun will elevate to the maximum programmed range (4000m for the main gun, 1800m for the coaxial). You can still fire on the target, but you'll need to apply additional superelevation manually.

To lase the target in ArmA, press the "Lock Target" button -- the Tab key by default. You can also use the "LASE" action in the action menu.

After you have lased the target, the reticle will be allowed to "float" if you move the sights. The important thing to keep in mind here is that your controls move the reticle. Wherever you put the reticle, it will stay. This is used for firing at moving targets. To cancel the reticle motion ("dump the lead"), just press the button you have bound to the "Look" function or select the "DUMP" action in the action menu.

To fire at a moving target, you must smoothly track the target with the reticle for 1.5 seconds before you lase. Once you lase the target, the sights will jump in front of the target to apply the proper amount of lead, while the reticle stays exactly where you put it. Continue to track the target with the reticle, and fire. If you've carried this out properly, you will hit the target. If the target changes speeds, all you need to do is continue to track the target for at least 1.5 seconds before firing. If the target changes range during this time, you can lase again--the laser always points to the center of the reticle.

The M1A1 turret traverse is such that you can actually hit a helicopter in flight. To have any chance of this, load M830A1 MPAT rounds and set the FCS mode to "MPAT (Proximity)". This will set the shells to detonate whenever they come within five meters of anything, after an arming range of 300-400 meters. (Unfortunately, it is not triggered by terrain. It seems to ignore rocks and trees, too.)

After each time you fire the gun, you must select the next shell to load. To reload the same shell type you have just fired, press the button you have mapped to the "Reload" action.

The minimum laser rangefinder range is 200m, while the maximum range is 7990m. If the target is less than 200m away or more than 7990m away, the range will flash "0000". (I think this should prevent the gun from firing, but I don't know how to do that in script. Right now I think the script sets the gun to maximum superelevation.)

There are a few extra controls in your action menu. "BSGT" sets the FCS to battle sight mode. This will set the range to the battle sight preset. (This preset will be adjustable in future versions, as of now, it's always 1200m). This is useful for firing APFSDS rounds at close range, if you don't have time to lase the target. Press the "binoculars" key to call up this mode.

"Range Logic" refers to the method of dealing with multiple laser returns. If there is more than one object in the 1-mil circle when you lase, you may see a bar appear over the range. This means that the rangefinder has seen more than one laser reflection. By default, the range to the furthest reflection is displayed and entered into the fire control system. By selecting the "Range Logic" action in your action menu, you can toggle between this behavior and displaying the range to the nearest laser reflection.

"Toggle Coax" does exactly the same thing as pressing the button bound to the "Toggle Weapons" action. It's displayed in the action menu because that's the only way the script will work.

T-72M Gunnery
Using the T-72M fire control system is rather more difficult than using the M1A1 FCS. Firing at a stationary target, however, is still pretty easy. To hit a stationary target with the main gun, you must make sure the proper ammunition type is selected, place the target within the red laser marker, lase the target, place the point of the large center chevron on the target, and fire.

The currently selected ammo type is shown by the big red letter in the middle of the screen. "O" means high explosive fragmentation (HEF), "K" means high explosive anti-tank (HEAT), and the Cyrillic "B" (looks like a "6") means armor piercing (APFSDS in this case). To change this, select the "Change FCS Mode" action in your action menu. Note that the firing solution does not update when you do this. (It probably should. Wait for the next version.)

To hit a stationary target with the coaxial machine gun, you must place the target within the red laser marker, lase the target, note the range, set the range to zero, place the point of the appropriate machine gun chevron over the target, and fire. The machine gun chevrons are the small chevrons that form a curve from right to left, and they are marked in hundreds of meters. To hit an 800 meter target, for example, you must place the point of the chevron numbered "8" (below and to the left of the main aiming chevron) over the target and fire. (Due to a problem with the BIS T-72 model, the 50-200 meter chevrons don't quite line up with the target at those ranges. The 50 meter chevron corresponds to ~30 meters, and the 200 meter chevron corresponds to ~180 meters. After that they're just about perfect.)

Lasing the target is accomplished with the "Lock Target" key or the "LASE" action. To set range to zero, press the "Look" key or use the "DUMP" action.

To fire at a moving target, you must place the target within the red laser mark, track the target smoothly, and hold down the lase key for ~1.5 seconds. As long as you are holding the lase key, the lead will continue to be updated. If you are using a joystick, you will not be able to hold down the joystick button to accomplish the same thing. Pressing a joystick button mapped to "Lock Target" is equivalent to tapping a keyboard key mapped to "Lock Target". As a result, the lead will only be averaged over the 0.1 seconds after you press the lase button. Fortunately, this is actually good enough if you are smoothly tracking the target.

As the lead is computed, it will be displayed by red LED numbers to either the left or right side of the reticle. When you release the lase key, the number will freeze. To fire on the target, place the top of the mil mark on the same side as the lead display that corresponds to the number on the lead display over the target, and fire. For example, if you are tracking a swiftly moving target that moves left to right across your view, the lead may be displayed as "22,0" on the left side of the reticle. To hit the target, place the top of the small dash on the left side labeled "22" on the target and fire. If none of that made sense to you (it doesn't make sense to me when I read it), watch the video.

The laser rangefinder in the T-72M is of considerably poorer quality than the one in the M1A1. It really does fill the entire red hexagon. In addition, it always returns the range to the first reflection it sees. If that wasn't bad enough, the maximum range is only 3000-4000 meters depending on the weather; the minimum range is 500 meters. If your target is further than 3000-4000 meters away or less than 500 meters away, no digital range will be displayed, and the sights will set themselves to 800 meters. To fire at targets less than 500 meters away with the main gun, just let the sights set themselves to 800 meters and fire -- you should be close enough. In future versions you will be able to change the range manually.

Although the rangefinder always returns the nearest range, you can lock out shorter ranges if you need to fire through trees. The minimum range can be changed between 500, 800, and 1200 meters for this purpose. For example, if you are firing at a 1500 meter target behind a few trees that are 700 meters away, and the rangefinder keeps showing 700, set the minimum range to 800. Getting an accurate range to a target that is more than 2000 meters away is very difficult; Soviet doctrine was to lase three times just to be sure. Keep in mind that there is a three-second cooldown phase between each laser usage that cannot be overridden.

This mod is currently to be regarded as beta. There may be any number of bugs in this mod, and I haven't tested it online at all. I would not try to test it online unless the server and each client is running the mod.

I still need to add:
-- commanders' optics
-- night sights
-- varying magnification levels
-- trunnion tilt corrections
-- fixed tank models

The BIS tank models have the gunner view floating in the air above and to the left of the gun. It's close enough for the T-72, but the viewpoint should be on the right side of the gun in the M1A1. In addition, the gun axis on the M1A1 is slightly misaligned. It's not enough to be a problem, but the laser may occasionally be misaligned with the reticle because of this.

I think this mod has a bit of a bug where lead will become unpredictable when traversing through dead south. I'm still trying to fix that.

If you use a 5:4 aspect ratio, the reticle positions probably won't be accurate. At all. You've been warned. 5:4 aspect ratios behave oddly in ArmA, and I'd have to make a second version for 5:4 aspect ratios. That wouldn't be such a big problem, except that I don't know how to do it. If you use any other aspect ratio, it will work fine.


To install, just extract to your ArmA directory and add @NWD_TankFCS to the "-mod=" switch of your ArmA shortcut's "Target" line. If you use multiple mods, the "Target" should be, for example:

Code Sample
"C:\Your ArmA Path\ArmA.exe" -mod=@NWD_Ballistics;@NWD_ScopeFix;@GMJ_SightAdjustment;@NWD_TankFCS

This mod requires the extended init eventhandlers mod! If you use GMJ_SightAdjustment, make sure to use the compatibility patch in the "examples" folder of the extended init eventhandlers mod. Just put it in your @GMJ_SightAdjusment/addons folder.

NWD_TankFCS v0.2 Released

This includes many, many changes:
-- AI T-72s now load APFSDS by default
-- AI tanks no longer try to attack by firing their rangefinders into the sky (???)
-- New T-72 machine gun ammo loadout (this should be the correct loadout, regardless of what you may find online)
-- many new ammunition types added to the config, although not yet programmed into the FCS.
-- New tank models, with many new features:
- main gun reticles are now accurate at any zoom level. Both tanks have two field of view levels that will automatically toggle when you zoom in or out by the appropriate amount (as long as you use the keyboard for zoom).
- T-72 turret is now declined 1°13' forward, as it should be
- T-72 driver can now unbutton (but the turret is locked when he does)
- T-72 commander's AA machine gun is now mounted on the rear of the cupola, and can no longer be fired from within the tank (the AI does not unbutton in combat, however, and thus will never use it)
- M1A1 commander's weapon station is remodeled to look (kind of) like the real thing
- M1A1 commander's machine gun can now only be fired from inside the tank or (unaimed) from a semi-buttoned position. You are currently not more protected when semi-buttoned than when unbuttoned. If you play with external views, you will still be able to fire ( and aim! ) the gun from the external view. You can also, due to a limitation in ArmA, zoom in to 3x magnification when semi-buttoned and looking through the vision block.
- M1A1 gun superelevation is now applied by physically moving the gun barrel after you lase, instead of moving the shell when it's fired.
- M1A1 dynamic lead is now applied by directly rotating the turret, and not by rotating the hull and relying on the AI driver to keep the hull stationary
-- New, radically different damage models. Tanks are much better protected on their frontal aspects, and are completely immune to small arms.

All the AI problems should be fixed in this version; they are very deadly now. Taking on an M1A1HA in a T-72M1 is usually a losing proposition, but if you can get the first shot you have a chance.

I still haven't tested this mod online, but it should be much more compatible than before. It relies heavily on animations embedded in the model, however, and I wouldn't be surprised if it requires the mod to be present on the server.

It's rather complex now, and I may have introduced lots of new bugs. I appreciate any and all bug reports. I'm aware of the model warnings in ArmA.rpt, but they don't cause any problems as far as I've seen. The degenerated faces warning is actually a false alarm, as it's referring to the (very small but nonzero area) faces in the TPD-K1 analog range display.
Picture of Tank Fire Control Systems
Size : 1,91 MB
  October 17th, 2007 - 08:52   Comment (0)  

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