Main Battle Tank Gun Ballistics, FCS, etc.

Following up on my small-arms ballistics, I'm extending the same to tanks. It took a lot of research, but I have fairly accurate trajectories and damage for several different 120mm/125mm tank shells. In addition, APFSDS darts will no longer destroy tall buildings in a single shot ( they had explosive=1 defined in the config! ). Here's the tank shells I've got data on (all unclassified, of course):

120mm M829A2 APFSDS-T

120mm M830 HEAT-T

120mm M830A1 HEAT-MP-T

120mm M908 HE-OR-T

125mm 3VOF-36 HEF-FS

125mm 3VBK-25 HEAT-FS

125mm 3BM-42 APFSDS

125mm 9M119 "Svir" ATGM

The Russian shells are from the late 80s, and are sometimes provided with export T-72M1 and T-72S tanks. The American M830 HEAT is hardly used anymore, but I have definitive trajectory data for it. M908 Obstacle Reduction is really just a steel-tipped MPAT, but I don't really know how it's supposed to blow up. I probably won't put those in default loadouts. That leaves MPAT, and I probably need to write a proximity-fuse script for those if I put in through-barrel ATGMs (for heli-defense parity). I really need more speed and thrust data on the Svir/Refleks missle, though.

The fire control systems are bastards, but I'm almost done with the 1A40 sight system on the T-72A. I've got the "technical description and operating instructions" manual for a Russian T-72A, and I'm implementing the sights exactly as my rudimentary Russian can interpret it (and I'm currently trying to OCR and machine translate it so I can figure out the dynamic lead display). This will, I believe, be the most accurate rendition of T-72 optics ever in a video game. If you've played T-72 Balkans on Fire, this is what the optics were supposed to look like.

Screenshots so far:

As you can see, I'm getting a bit carried away with the scripting, going as far to put in ammo-specific dispersion and the like. I didn't get a screenshot, but the co-ax follows the curve of the aiming points, too. It's not calibrated very well for long range, but the "0,5" to "8" marks are nearly perfect for 50-800 meter fire (after you've canceled ranging as in the first screenshot).

The sight is 6x instead of 8x so you can shoot HE-Frag shells out to 4km (and HEAT out to 3800m or so). Nothing I can do about that. You should actually be able to area-fire HEF out to 5000 with the marks on the right side of the graticule, but that would mean 4x zoom or something horrible like that. I'll try to put in a toggle for the TPN3-49 or 1K13 sights for night-vision and through-barrel ATGMs, too, so 6x isn't a bad compromise.

ATGMs will fire just fine out of a tank gun, in case you were wondering, but ArmA's ATGMs don't work past 1500m. This makes them completely useless, of course, since they're designed for 3-4km range. I might try to script my own bar-scan beamrider instead of using ArmA's guided missles, but I don't expect miracles. This would rightly be for a T-72B/T-72S instead of ArmA's T-72A/T-72M/T-72M1/whatever, but I'm not losing sleep over it.

Lead isn't computed yet, because I'm not sure how the lead is computed in the real thing. I'm sure it's in my Russian T-72A manual, but I can't understand it. What I do know, is that once the lead is computed it's displayed on the left ocular, and as the gunner you're supposed to put the corresponding lead mark on the target. For example, lasing a target moving left to right would show a number on the left side of the display, at which point you would align the corresponding left lead mark with the target and fire.

I've got a few problems, though. First, I can get a 3D object with a range spinner to show up on my overlay (not shown in the screenshot), but there doesn't seem to be any way to make it spin. Is this correct? Is there to way to set the "up[]" vector in script? The 1A40 has a LCD range display in a second eyepiece, so it's not a total loss, but I'd like to get this working.

Second, is there a way to change a player's turret direction in script? I can make the M1A1's GPS reticle float without a problem, but it won't work correctly unless I can move the gun as well as the reticle when you lase. If I rotate the whole tank, will the turret move along with it? What will happen if I rotate the tank while it's moving? I could probably just give a 1-2 second grace time before the floating starts, but I'd like to avoid that.

Nice!

If its as good as your weapon ballistics then i already love it.

Im sure our tank nut Kenji will love this, gotta point him to this thread

Quote[/b] ]As you can see, I'm getting a bit carried away with the scripting, going as far to put in ammo-specific dispersion and the like.

If you're using eventhanlders, please use Solus' extended init and fired eventhandler addon from here. It keeps our mods compatible and can also mean that the nearestobject command is only run once per projectile and not for every mod running.

Not everyone is using the fired evenhandler from that addon yet, but I will with the next version of my mod.

Oh God yes!! Will the reticle scales correspond correctly with the individual levels of magnification?

-edit-

Okay I'm really exited about this because you might lure some SB Pro PE people over to ArmA

I have some more questions:

#Will this be a standalone addon or a replacement pack?

#Will the LRF be able to sustain damage forcing you to switch to GAS and/or manual range entry?

#Will there be manual range entry?

#Will this be only for the gunner or will the TC get some love too?

#Is reticle illumination possible?

#Could you use the same system as damaged textures in a night vision'ish mode to simulate TIS? ie. once you switch to TIS all vehicles and infantry switch to really bright texture.

This looks like the most awesome thing to hit ArmA yet!

Thanks!

wow, impressive

[1]Oh God yes!! Will the reticle scales correspond correctly with the individual levels of magnification?

-edit-

Okay I'm really exited about this because you might lure some SB Pro PE people over to ArmA

I have some more questions:

[2]Will this be a standalone addon or a replacement pack?

[3]Will the LRF be able to sustain damage forcing you to switch to GAS and/or manual range entry?

[4]Will there be manual range entry?

[5]Will this be only for the gunner or will the TC get some love too?

[6]Is reticle illumination possible?

[7]Could you use the same system as damaged textures in a night vision'ish mode to simulate TIS? ie. once you switch to TIS all vehicles and infantry switch to really bright texture.

This looks like the most awesome thing to hit ArmA yet!

Thanks!

[1] -- Unfortunately, proper reticle scaling seems impossible. I can't find any way to read or write player FOV. I might be able to hijack the zoom in and zoom out buttons and scale the reticle when you push them, but that seems way too buggy to be useful.

[2] -- My other mods were replacement packs. This one I'm not so sure about. Right now I've changed weapon and ammo loadouts for the tanks, which means they wouldn't be muliplayer compatible. I don't know if it would be compatible if I add the new ammo through a script instead, but I'm guessing no. I'll probably make two versions, one that uses default ammo loads with new ballistics, and one that uses realistic ammo loadouts (so you can have HEF, HEAT, and APFSDS rounds in the T-72, for example).

[3] -- I plan to make a random damage script for the LRF. Nothing fancy, but some way to force you to use the auxiliary reticle or the manual ranging.

[4] -- I'll use the arrow keys for manual range entry, once I figure out how. I'll probably scavenge some code from GMJ_SightAdjustment, since that mod is defunct. I might even make my own version of SightAdjustment eventually, so I can put floating reticles on PSO scopes and fix BDC cams.

[5] -- TC optics are on my to-do list. Unfortunately, I can't find any way to make commander's main gun sights. I can't change the view point or give the commander control of main turret traverse. There's no way to do hunter-killer, either, since the commander can't slew the turret.

[6] -- Reticle illumination is not only possible, it's required. My reticles are part of a cutRsc overlaid on the screen. Lighting isn't applied to display elements, and the only way to control their color or brightness is through script. All I have to do is draw my reticle in a different color, and it's illuminated.

[7] -- I plan just to add NVG to the gunner and toggle them in script when you switch to a night sight. This would be correct for the T-72, which uses light-amplification optics. For the M1A1, I don't know what to do. If there's a way to force black-and-white display and change textures on everything, then I might look into it. I'm too poor an artist to make all those textures myself, though.

This uses the extended init eventhandler mod, and adds fired eventhandlers through script. I didn't know there was an "extended fired eventhandlers" out now, but I'll probably use it since my current implementation seems prone to bugs.

How about a HUD as a reticle instead of an image? That might solve the scaling and illumination problem? To complex stuff maybe?

good idea...

but you need to expand this idea, like taking, M829A1;M829A3(1st & 3rd generation) DU rounds; 3BM-42M, 3BM-44 and lots of more rounds...

and for russian rounds, if you want to simulate-stimulate real rounds used by soviets/russians, DO NOT USE EXPORT VERSION DATA!!! just a riminder, so that T-72s used by russians wouldn't be such weak things like iraqi's T-72s...

eh, i heared something about Kenji? How he's doing?

P.S. I hope this project will be very realistic

good idea...

but you need to expand this idea, like [blah..blah]

Methinks he needs to get it all working nicely first. This is a

very good initiative, though. A first step on the long

road to getting ArmA MBTs to behave more like their real life

counterparts (and not like the stupid toys they are now).

There is a way to make a reticle that will allways have the same MOA. Well, it works well for rifles, haven't tried out for vehicles. You can add the reticle into gunner view and export it to proxy.

At least with rifle models when you enter sights mode (the 2d one) the model of the weapon dissapears yet the proxy, if there is any attached in current view, stays in front of you.

Try adding a proxy of reticle to either the current LOD of model (view gunner, view commander or sth) or sights model itself (not sure if supported).

Most US tank shell trajectories are classified. The DoD released firing tables for M829, M829A2, and the M865 training round, but that's it. I found an unclassified document with M830 and M830A1 ballistics, too, although I didn't expect that.

Russian ammo is even harder. I got most of my data from a photo of a T-80U commander's gun sight(T-80 tanks aren't offered for export, so I don't have to worry about non-Russian ammo). I'm pretty sure the APFSDS scale was for 3BM-46, since the matching trajectory has ~60 m/s/km speed loss. I don't think 3BM-46 will fire out of T-72A or T-72B guns (they can't take the stress), so I put in 3BM-42 ammo, which supposedly loses ~85-100 m/s/km. 3BM-42 is an export round nowadays, so it's not completely unrealistic to see in Sahrani. If I wanted to be realistic about export ammo, though, I should probably make 3BM-15 ammo--even though you'd be better off with HEAT.

Export ammo isn't really special, it's just old. During the Soviet era, the most modern APFSDS shell exported was 3BM-15, first introduced in 1968! Nowadays, though, 3BM-42 ammo is being sold with new T-72S and T-90S tanks, and 3BM-42 ammo still makes up the majority of Russian 125mm APFSDS stock.

For that matter, the modern export T-72S models are actually better than the majority of T-72B models in Russian service. Russia's hurting for money, so the Soviet "monkey model" thing is completely reversed. There's actually a new T-72B "Rogatka" upgrade as of last year with dual-stabilized thermal optics, automatic fire control, the V-99 engine, and brand-new "Relikt" ERA, but I don't know if it's ever going to be widely deployed.

____

A proxy model added to the viewpoint, you say? I hadn't even thought of that. Wouldn't I need to add it to the model? I think I'll need an example to figure this out.

Can animations be applied to proxy models? I really need a way to make the range spinner spin.

I was thinking of just making the range spinner a vehicle and positioning it in front of the sights every frame, but that would probably stutter like hell. I've done all the trigonometry already, though, so it wouldn't be impossible.

There might be a way to do TIS with shaders, but I'm not sure of you can script those. As an artist I can certainly give some suggestions on how to simulate TIS.. in fact, to give a rough and dirty approximation, it would not be very hard at all.

Some prior mod has been able to simulate a forced black and white gun-sight display using the aperture settings. This gives a nice effect- the problem is that since you are using the HDR aperture to achieve that effect, things like explosions and stuff won't dynamically wash out the display like they do on thermal images. In order to achieve that kind of wash out you'd need to use some kind of billboard texture or animated particle, which might look alright if a lot of time was invested in it.

As for the rough and dirty approximation of TIS, without any research, mind you, you could take the existing diffuse textures for the terrain and darken them slightly and completely desaturate them, then take the the textures of hot vehicles and people and decrease their contrast a bit, darken them slightly, desaturate them and then invert their values. This, I think, would give an alright illusion of a white-is-hot image. Another avenue to explore would be the gradient map feature in photoshop. That can produce all kinds of weird but controllable and refined effects by controlling what colours you wish to replace at what point on the grey-scale of an image. For example, you could replace the dark areas of an image with a high grey value, the mids with a mid grey value, and the light points with a slightly lower or higher grey value. This would give a more controlled effect than simply inverting the image.

The problem with any of the above would be that there would be no dynamic interaction between how 'hot' the object is and what colour it is... for bodies cooling, this would really only be an issue for longer missions but it would still be a factor. This is why it would be nice to be able to control the game engine's shaders. We already know that shaders can be made to effect objects per class or an image per-pixel, or a combination of the two. With those you might even be able to script or otherwise implement a shader that simply inverts the black and white values of the display pixels, enabling the user to flip between simulated black and white-is-hot modes.

If anyone is game, the above information should be a good starting point to say, make an action script for photoshop which would automate the texture generation process almost completely. The wild cards here are whether or not such a basic implementation like that meets criteria for quality and accuracy, whether it's worth it from a resources management standpoint (system or personal), and whether such a thing is even possible through scripting or other methods.

The problem here is that there is no possibility that I can put my money where my mouth is at this time. I'm in quite a dense program at school and every spare moment I have is essentially spent doing school work. If anyone would like to talk about any of the issues I raised above, feel free to contact me.

ATGMs will fire just fine out of a tank gun, in case you were wondering, but ArmA's ATGMs don't work past 1500m. This makes them completely useless, of course, since they're designed for 3-4km range. I might try to script my own bar-scan beamrider instead of using ArmA's guided missles, but I don't expect miracles. This would rightly be for a T-72B/T-72S instead of ArmA's T-72A/T-72M/T-72M1/whatever, but I'm not losing sleep over it.

Mandoble?

QuietMan

REALLY looking forward to this. You're perfectly on your way to being an ArmA God. The God of Ballistics.

Quote[/b] ]You're perfectly on your way to being an ArmA God. The God of Ballistics.

I can only put my name under this statement.

Damn great work. You are increasing the quality of ArmA by at least 100% IMHO.

Looks great! But yes make sure if you want to simulate real Russian tank ammo to give it a boost from the export version info. Hell, I'd think just making it have very similar ballistic properties to US ammo of the same age would be accurate enough.

Also if you need a beta tester I'd happily plug away with this for a few hours, I'm a huge T-72 buff. It's just a shame ArmA's armor system is complete crap and my proposals to improve it have been ignored.

Also will your shells have deflections enabled? Here is a good guide to use for a wargame. I've messed around a bit with the subject and got some promising results.

Armor and shell guides here. Perhaps you could compare the data here to real data and then use that difference to get a rough idea of how to do the Russian ammo.

http://members.tripod.com/collinsj/protect.htm

Also, If I remember correctly the US measures it shell penetration ability from a different angle/distance than other countries so make sure you have considered that.

Also, having deflection values would hide ArmAs lack of front/side/rear armor to a degree. Since most tanks have their fronts sloped alot more heavily than the rear and sides it would mean that shells would deflect more frequently off the front quarter than the side or rear ones.

well i see that you know the thing quite good

yeah correct data will be a problem which we can't solve, too much secrecy.

and T-80s were exported...

Excellent idea, hope this comes to fruition.

First off, I'm not sure there's an appreciable difference between (possibly Ukrainian-built) 3BM-42 used by the Russian military and Ukrainian-built 3BM-42 sold for export. The Russians have 3BM-42M and 3BM-46 shells that are not exported, but that's different. Those two make up a tiny proportion of the Russian inventory, anyway.

I was also under the impression that Russia didn't export T-80s, just like they didn't export T-64s. There are "exported" T-80s, but they're Ukrainian-made diesel models with different electronics.

Looking at again, though, I find that my source identifies the sight photo I have as a TKN-4S sight mounted on a T-80UD, and not a T-80U. Eh, I can't find data anywhere else. No complaining unless you have something to offer.

I'm not sure how to do deflection, but APFSDS rounds do not "deflect." They really just bend, snap in two, and send half their mass into the target. HEAT rounds wouldn't deflect, either.

I've changed damage so that a single round will no longer immediately destroy a tank (a T-72 will still be completely disabled by a single sabot round, but it won't immediately blow up), so I might actually be able to fudge different armor thicknesses from different angles. It would be simple enough to find the angle at which the round hit and add hitpoints back to the tank based on that. I don't know if that's a realistic solution, though.

First off, I'm not sure there's an appreciable difference between (possibly Ukrainian-built) 3BM-42 used by the Russian military and Ukrainian-built 3BM-42 sold for export. The Russians have 3BM-42M and 3BM-46 shells that are not exported, but that's different. Those two make up a tiny proportion of the Russian inventory, anyway.

I was also under the impression that Russia didn't export T-80s, just like they didn't export T-64s. There are "exported" T-80s, but they're Ukrainian-made diesel models with different electronics.

Looking at again, though, I find that my source identifies the sight photo I have as a TKN-4S sight mounted on a T-80UD, and not a T-80U. Eh, I can't find data anywhere else. No complaining unless you have something to offer.

I'm not sure how to do deflection, but APFSDS rounds do not "deflect." They really just bend, snap in two, and send half their mass into the target. HEAT rounds wouldn't deflect, either.

I've changed damage so that a single round will no longer immediately destroy a tank (a T-72 will still be completely disabled by a single sabot round, but it won't immediately blow up), so I might actually be able to fudge different armor thicknesses from different angles. It would be simple enough to find the angle at which the round hit and add hitpoints back to the tank based on that. I don't know if that's a realistic solution, though.

I know that sabot rounds don't deflect really, but theres no way to model them snapping in ArmA so really the best course off action is to have them hit the tank and bounce off at range to simulate it.

I like your idea about adding hitpoints which would be better than the current system, but I was sort of under the impression that when a modern AP round penetrate it did a LOT of damage to the tank. So perhaps rather than adjusting hitpoints for the various sides perhaps adding and reducing deflection would work better. Having the shell bounce off could simulate the round breaking or partial penetrations to the front armor but when the high damage round did go through it would mean the tank was pretty much disabled and we would have injured crew, explosion, etc. The adding and removing hitpoints would work better for HEAT rounds in my opinion where velocity doesn't matter but only angle of penetration does.

Looking forward to your T-72 addon though and I think the T-80 sight would also be great. I know Kenjis up and coming T-64 addon plans for a few variants including a Ukrainian style one If I remember correctly so the T-80UD sight would work nicely on that. I also think that a properly working T-72 and T-80 gun sight could be adapted to work with almost all if not all Russian tanks quite easily.

Some Info about T-80 variants and export.

T-80UD is as you said a Ukrainian version, this variant is also the version exported to Pakistan.

Most common Russian variant is T-80U and T-80UM. T-80U is from 1985 and features a new turret, Refleks ATGM, 1,250 HP Turbine Engine, and Kontakt-5 ERA which defeats APFSDS and HEAT rounds.

T-80U(M) is T-80U with improved fire control, not sure if you would need to make a new gunsight for this one.

T-80UK and T-80UDK are command variants, uprated GTD-1250 engine, Shtora countermeasures system, thermal sight, fire control, navigation system, and APU became the main Russian export tank in the 1990s.

T-80UE is a simplified UK offered for export since 1999.

T-80UM is modern version with improved thermal sight.

I think your T-80UD sight and fire control would be sufficiently realistic for that and all prior T-80 variants. Not that I would be complaining about seeing it on modern variants as its better than anything else we'd have most likely. I'd imagine it would also be suitable for the T-90 which uses the same gun.

Also, the deflection system is already prebuilt into arma, I believe its deflect = chance or deflection = chance, something along those lines in the cfgammo.

I've got my doctor on hot standby for an emergency sex change operation, because when I see this in A&M:Complete, I AM having your child!!!!

Very good and promising!

And yes, I agree with everyone that the east needs a better MBT, trying to fight M1A1s in a T72 is close to suicide IRL (well, with some reservations, but anyways). T80 / T90 FTW!

Off-topic, but relevant: DOes anyone know what happened to the T90 that was in development?

http://www.flashpoint1985.com/cgi-bin....7;st=60

Probably a project that could make good use of these ballistics.

I've got the lead computer working now. It takes the average turret traverse rate over the last 1.5 seconds and uses that, along with flight time, to compute the required lead. In the T-72, lead is only displayed when you push the "lase" button, and it is not continuously updated. This makes it an absolute bastard to use, and you will more than likely get the wrong answer if you're trying to track the target with a mouse. Get a joystick.

If I'm reading my source right, lead in the real thing is continuously updated for as long as you hold down the lase button, and it works as in my mod once you let go. That doesn't work for the action menu, but I'll try to assign a key for the laser. In any case, you have to apply the lead value manually with the mil scale.

All that said, it does work. This is not an easy thing to do, firing at a fast-moving medium-close target using HEAT:

http://gallery.filefront.com/NonWonderDog//784538/

http://gallery.filefront.com/NonWonderDog//784539/

http://gallery.filefront.com/NonWonderDog//784540/

I've also changed the laser mark. The photo on Stephen Kosch's site shows a big hexagonal marker, and that's what I went with originally. I have to conclude that that's not a Russian TPD-K1, though, since my manual clearly states that the inner diameter of the laser marker is equal to the dispersion of the laser beam. [EDIT: I've changed this back. Apparently, I was vastly overestimating Soviet optics. The laser apparently does have 2+ mil divergence. Now I have to code in multiple returns...]

I still haven't figured out a way to make the range spinner work. Right now I just have a black number up there where it should be.

Quote[/b] ]This makes it an absolute bastard to use, and you will more than likely get the wrong answer if you're trying to track the target with a mouse. Get a joystick.

Hey don't blame the mouse-user for this "lase" button... it's a combat simulation you have to choose what is good for those "armchair-tank-crews"

imagine you must write real loader-simulation for MBT.

ARGH!

When I was trying to test the APFSDS mode, I found out that I've got 2.5 km cull distance in ArmA, beyond which NOTHING is displayed except land. I could very clearly see my target disappear into nothingness as I tracked him, and I couldn't see my shell impacts at 3 km. At least the rangefinder still works.

Is there any way to fix this? Or is it tied to my view distance somehow?

Better news, however, is that I could semi-consistently get a third- or fourth-shot hit on a moving Abrams at 2.3 km. That's about what was expected of Soviet tankers, and the reason they started equipping tanks with ATGM.

Also, I've modified T-72 and M1A1 turrets to their real traverse and elevation rates. The M1A1 turret is only a little bit slower than the default, but the T-72 turret is SO SLOW, you'll instantly get pissed off if you try to rotate 360 degrees with the mouse. You'll get even more pissed off if you try to change the gun elevation...at all. It's about as fast in powered mode as the M1A1 gun is in hand-cranked mode. Another reason to get a joystick (or bind keys to "aim up/down/left/right"), I guess. The joystick will only give you full traverse rate if you're zoomed out to 1x magnification, but that's an option I've provided.

You can still track a target with the mouse, and I used the mouse in those screenshots above (too hard to use the joystick work the action menu and push PrtScn at the same time). You just won't be able to effectively scan for targets with the mouse. It is also very hard to keep the reticle on center mass of a moving target for 1.5 seconds while using a mouse, and there's nothing I can do about that.