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May 14, 2013

Artillery in Real Life

By EnsignExpendable

With the upcoming artillery nerf rebalancing coming, I thought it would be interesting to explore what artillery could do realistically. I have previously looked at how well HE works in real life, and it seems to work pretty well with even small calibers. Large calibers, like 152 mm, work even better.

Ferdinand after a direct hit from a B-4 203 mm howitzer.
The thing is, these tests only cover what happens on direct impacts, which, as any artillery player will tell you, are few and far between. Even the Object 261, heralded for its accuracy among the SPGs, has an accuracy of 0.42, which is pretty miserable for a tank, especially when shooting all the way across the map.

That range is where the problem with real life artillery comes in.

Long range accuracy for the 76 mm model 1942 gun at full propellant load, and 122 mm model 1938 howitzer, at first propellant load.
This figure from a Soviet artillery textbook demonstrates how inaccurate a gun can be at long range. The 76 mm gun has similar ballistics to the T-34's F-34 gun, which does not miss a StuG-sized target at 950 meters. That's pretty accurate. However, at a range of 3 km, the horizontal dispersion is 8 meters, or 2.66 StuG widths. At 5 km, that distance increases to 20 m, 33.6 m at 8 km, and 30.4 meters at 10 km. At those high ranges, it is also easier to overshoot, especially if you are using a low velocity gun with a high arc.

Since in-game accuracy is much poorer for all guns than real-life accuracy, let's do some conversions. The model 1938 howitzer (M-30) exists in-game on the SU-85. Its accuracy at 100 meters is 0.55 (somehow, the model 1930 howitzer on the SU-26 is slightly more accurate), meaning that shells at 100 meters would fall within a circle that has a radius of 55 cm. At 3000 meters, this circle would be 16.5 meters in radius, or 33 meters in diameter. Compared to the real life circle, 12 meters in diameter, 122 mm artillery is roughly three times less accurate than in real life. . Compared to how badly the D-25T got shafted (5.75 times), the equivalent caliber artillery gun gets off easy.

All right, so indirect fire in real life is inaccurate too. But everyone knows that arty relies on splash! Let's take a look at how well splash works in real life.

Craters from high explosive shells, with the fuse set to explode in the ground.
As you can see, the 152 mm shell digs out quite a pit with its explosive power. A 420 mm shell (not shown due to scale issues) displaces 250 cubic meters upon impact. Thankfully, there are no artillery pieces with such a massive caliber in this game. Even if a tank is not destroyed by the explosion, it will have a hard time getting out of the pit.


This figure only illustrates how much destruction is caused by the explosive force of the shell. However, artillery shells damage tanks not only with expanding gases, but also with shrapnel. The spread from shrapnel is not in a circle. It flies out more to the sides than front or back. The measurement of a shell's shrapnel effect is a rectangle within which 50% of the targets are struck by shrapnel. The following figure illustrates these areas for some Soviet guns.

Areas of damage for a 152 mm shell, 122 mm shell, 107 mm shell, and 76 mm shell. The direction of shot is from left to right. Shells are set to explode in the air.
Of course, these rounds are designed to destroy infantry and soft vehicles, and we are dealing with tanks here. However, shrapnel can still destroy tracks, optics, and wheels. In game, the damage from an artillery shell should be some mix between damage from the explosion and damage from shrapnel.

The in-splash on the SU-26 122 mm model 1930 howitzer is 2.49 meters. The splash on a stock S-51 152 mm gun is 3.66 meters. Comparing this to the crater sizes, the shrapnel is considered as barely contributing to the destructive effect at all.

And now for the biggest difference: the "satellite view". Obviously, artillery cannot aim like that! However, there are ways to aim at things you cannot see, although you need people correcting your fire.

Before the start of a battle, the battlefield is carefully studied by the battery commander. Forward observer points are established, distances to various landmarks (a house, a lone tree, a fork in the road) are recorded. When a unit radios in for artillery support, the artillery battery aims in at a visible target at the same distance, and then changes the angle to aim at the invisible target.

Aiming at a target you cannot see.
This is where some math comes in. The forward observer and artillery battery will see the angle of the explosion differently. Using the difference in angles, and some quick trigonometry, it is possible to dial in. Since it would be decades before cheap calculators that could handle trigonometry, you would retrieve your data from a table of pre-calculated values.

Calibrating your shots on a target you cannot see. The battery commander must work with an observer to accurately gauge the distance to the visible target, then adjust the angle to hit the invisible target.
This is quite a bit more complicated than "point-and-click", of course. It takes some time, and some shells, to be able to fire accurately at a target you cannot see. The aiming does not need to be as precise as in-game. Instead of only one gun, you are firing with an entire battery.

In-game, your interface is an abstraction of the data that a well-trained crew can provide you. Assuming that the people spotting for you are trained artillery observers, and your map is in good order, an artillery crew should be able to dial in reasonably quickly, especially on maps as small as in-game. Hitting a moving target, however, would still be very difficult. A huge bloom when rotating your tracks is very much realistic.

61 comments:

  1. I can only imagine what abyss can 800mm shell can dig out.

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    1. Crater depth doesn't increase as fast as the shell size dozes. A 406mm/16" HC shell digs out a crater 50' wide but only 20' deep (15.25m x 6m).

      On the other hand, there are no trees left within 90 meters of the crater....

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  2. Here's an idea:
    Artillery aims at a target with poor accuracy, but with every shot, he gets more accurate, to simulate the constant re-calibrating and what not. But, if say, you move the crosshair more than 5-10 meters, this accuracy bonus is lost since you'll have to re-calibrate all over again.

    This will allow arty to do what it's supposed to do, which is taking out dug in tanks, or forcing them to move from their cozy spot atleast, without allowing it to shoot moving/frequently relocating targets as easy.

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    1. Sounds like you'd waste a lot of shells and make it even easier to counter battery. God help you if you have a GW Tiger with a system like that. If you want to change arty into area denial weapons you just need to mess with the stats. Reduce accuracy and shell damage. Make reloads and aim times faster. Increase splash radius. Add some more ammo storage and increase health since they no longer can kill things in one shot.

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    2. Actually the aim time should be increased quite a bit not shortened, that would mean you cant just jump around the map for targets (you can just get out the campers) and can't snipe down moving targets.
      The other thing that should be changed is penetration, so that you cant make those silly shots, you still could penetrate roof from time to time, but no more regular loosing of 75% hp in one shot because of unlucky position and shot in side armor.

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    3. >>but with every shot, he gets more accurate

      That is supposed to be in World of Battlships AFAIK :)

      Delete
  3. Omg, i want ground destruction in WoT...
    I want to be able to destroy rocks, hills and stuff like this... Maybe this will be the next big thing in WoT...

    Just think at all the possibilities... Tank in hulldown in front of you? Load few HE shells and destroy the hill...

    Someone takes cover behind a rock...blast that rock....

    A scout is driving at full speed? Shoot one HE shell in front of him to make a crater...He gets stuck inside...

    Oh...I SO WANT THIS

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    1. This is an excellent idea and I'm pretty much sure that WG would like to implement it but it's probably not the easiest thing to do.

      RedBear87 (EU)

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    2. -Would wreck the servers, make sections of the map hard or impossible to traverse (but arty discourages camping and promotes moving, right?), and generally be a pointless gimmick. -Platypusbill

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    3. This would be extremely difficult to process, as awesome as it would be.

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    4. Well, i was playing Men of War (rts game)and it was possible to do this. Yep, WoT is not RTS, but this is still a possible thing to do. And let's face it, WG is a pretty big company at the moment, they do have the money and the manpower to do this.

      If they implement this, they could finally change the game from 0.x.x to 1.x.x.

      Oh, and blowing stuff would also make HE shells more important. (atm i'm not even decaping with HE, i just use gold shells...as i can aim good enough to make sure that i'll decap)

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    5. well anon above me more or less pointed out what i was going to say, also it takes a lot of shots to remove even a small hill

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    6. The terrain is deformable in T-72 Balkans on Fire. This is well exploited by the game, where you can see trench diggers in action, infantry taking position in them, and you can yourself use an entrenching blade on your tank to dig a hole and go hull-down. I recommend this game if you want a less arcade experience than World of Tanks.

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  4. WG server will crash after that :)

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  5. The worst part for me isn't just the ability for SPGs to act as orbital lasers, but that they're given the firepower and mobility to match tanks in a direct fire battle as well.

    Real life artillery also usually employs spades and plows to stabilize the gun, not driving around like a high-speed emergency tank destroyer. Half the SPGs in the game can't fire in travel mode (TD mode), and another half have dismounted crews that certainly won't be running alongside loading the firing that gun while the SPG is chasing tanks around.

    Watching an SPG pull up the spades and play "chase the secretary around the desk" with an enemy tank is one of the least believable scenes in this game.

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    1. This is a moot point, AMX 13/75's crew should disembark to reload the gun but it doesn't happen in game, do you know why? Game balance.

      RedBear87 (EU)

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    2. This myth again... AMX-13/75 can reload its drum even from the compartment, but it's very uncomfortable and slow.

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    3. It's fun to imagine the crew running after the AMX 13F3, since the vehicle itself can carry two, maybe three, people.

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    4. Same way that you can repair your tank track in less time than a F-1 pit stop, just clickin 2 buttons, even if you dont use a repair kit you can repair it in less than 12!!!!!! seconds.

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    5. >This myth again
      Ok and a crew can repair a jammed turret in 10 seconds, it still doesn't change that this is a game which made tons of compromises, but people want realism only with arties.

      RedBear87 (EU)

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    6. Artys are also able to repair their tracks in 10seconds.

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    7. It's a game - I can live with 5 second track repairs. What pisses me actually off is are the made-up tanks and guns with blatantly fantasy properties... 192mm pen 75mm... -.-

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    8. It's an arcade game not a simulator. Expect many unrealistic things to be going on. Arty has to be able to protect itself somehow. In reality that would be handled by infantry and armored forces on standby. In game it's represented by arty being able to fire on the move.

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    9. The AMX crew did reload the rounds externally in most cases, but only because they were usually used in hidden dug in formations, so while a few other tanks were covering him the empty AMX crew just casually strolled out and reloaded the ammo.

      But of course people enterpret this as the crew only being able to reload from the outside, read properly anon.

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    10. To quote a classic: "You want realism, join the army!"

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    11. amx 13 reload time inside the tank was around 15-20 min and definitely was impossible on the move.

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    12. except the devs want arty dmg to be realistic by one shoting tanks

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    13. Its always fun to play endgame tanks (T10) which is the most powerful and still be able to be 1 shotted by artillery....

      -Joa

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  6. IMO best solution for arty problem is remove the fucking splash. That's right. If you want to do damage, then try to actually hit the tank. If not, then go home pal.

    This is where skill would come into effect.

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    Replies
    1. they don't lob solid pieces of metal.

      they lob solid pieces of EXPLOSIVE (encased in metal).

      any normal person knows that explosives EXPLODE.

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    2. Now think about this, every arty is using 240mm+ pen, its enough to pen most tanks frontally. They 1 shot everyhing in their tier. Now i have a question. Is it better to play where every arty hit means 1 shot or where u can do some damage with splash or some with direct he hits(he penetration is very rare).
      I am telling i am shooting AP with my M40/43 and i can say its not fun from tier X tanks point of view to get a 1800 hit frontally from arty.

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    3. lolwat? playing arty is the same as playing slot machines there is no skill involved, you just hope ur accuracy is good enough to land a direct hit on ur target without splash arty aint gonna do any dmg and no amount of skill is gonna save u.

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    4. With accuracy of almost 40% with almost any arty... That is quite high for me. But without splash... Dear god would the damage output be horrid... Sometimes digging tanks with 100-200 per splash because I can and nothing else to shoot... it dies eventually... in many many minutes.

      Arty isn't that much slot machine as many think, yes the accuracy is horrid, but that is how it should be. I like how arty is now... having lower accuracy makes it true slot machine... Sad way of balancing already good balanced tanks as for me they are balanced... I get _almost_ same output for T6 arty as T8 tank T7 arty vs T9 and T8 vs T10, but I do have 60% WR, which might incluence it, but still I have less DPMatch in arty in comparison to tanks and their WR is that high as those of tanks, thus making conclusion of arty having less impact than a tank in general.

      I hardly think they needed nerf, but WG to delete their current MM and rewrite for 0-3 arty max battles. Let arty players que up... they know there is too many of them if they can't get to a match in 5 min... Better than the whining about 4+ per match.

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  7. I thought it's S-51 on that first picture.. then I was like w00t.. ferdinand?!! Where?!

    And S-51 wasn't ever produced, was it?

    Hajvanho

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    1. Not mass produced, no. However, the guns that it has in the game were produced, although not in a self propelled configuration.

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    2. You are wrong here prototype of S-51 was created (according to wiki)
      http://wiki.worldoftanks.eu/S-51

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    3. I said /mass/ produced, not just produced.

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  8. Nice interesting article. Going to be seeing lots of flame and spam the closer we get to 8.6 and the artillery re balance!

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    1. You mean you don't normally see lots of flame and spam? :P

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  9. I really enjoyed reading this post. Thanks guys for posting!

    Denial_of_God (EU), the one who does NOT approve intended "arty nerf to oblivion and far beyond"

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  10. That Ferdi doesn't look good... :D

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  11. I don't agree with the nerf as is but I know the artillery is a bit too accurate but the 0.8 accuracy thing is a bit much. I was looking for the 0.5-0.7 on the guns. But with reality considering how stupid small the maps are and how other guns have 0.3-4 accuracy I have no problem with the current system as it exists. If the best artillery accuracy was 0.5 in game, even that would be decently fair as even with a sitting tank you wont hit it every time.

    As for the article it is very very good and maybe people will be less incline to go loco with artillery when it cant save them.

    NEMO.

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  12. If you ever want to understand how a real gun is tossed into a game check this guy out. Been following him off and on for several years.

    From the Main Page: "The Dreadnought Project is a naval history wiki focusing on naval history in the period 1880-1920, with side-projects in 3D modeling and simulation."
    Main Page:http://www.dreadnoughtproject.org/tfs/index.php/Main_Page

    Simulated Ballistics
    http://www.dreadnoughtproject.org/tfs/index.php/Sim:Ballistics

    I can only, ONLY, hope WoWS is half as dedicated. Also check out the original blueprints if you have a chance. Very cool.

    NEMO.

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  13. Since a forward observer was needed irl, why dont WG enable arty to only see targets a light tank spots...

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  14. If the UAV's of Artillery would be visible, we could shoot them down.. then Artillery has to go into TD Mode.. :P

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    Replies
    1. Watch out for these Vehicles very careful -> http://en.wikipedia.org/wiki/File:MQ-8B_Fire_Scout.jpeg

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  15. some interesting news about the mm:
    http://wot-ro.blogspot.de/2013/05/wots-matchmaker-is-rigged-proof.html

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    Replies
    1. Yes, it's interesting. SS, perhaps you can write an article with your comments and thoughts about this.

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    2. The patent seems to include alot of stuff that hasnt been put to use yet, how do we know that is not the case with this?

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  16. Very nice reading about how arty was but there is one thing I want to know more about and thats the penetration one arty. I think it sounds very wrong that arty could go though over 100mm steel. In WOT i think the high penetration chance is the worst thing about arty right now. I think they should lower HE penetration by 50% maybe buff the damage a bit.

    Btw im kind of new on this blog and i like it alot keep the good work up!

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    Replies
    1. Click the second link. The ML-20 can penetrate over 100 mm of steel, so why shouldn't the Br-2, which is the same caliber, fired at a higher velocity?

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  17. Google "US Army Artillery vs Tanks", even modern tanks are made combat incapable by 10/15/25m "close calls".

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  18. The Ferdi in your picture is hit by a bomb of pe-2, not from 203mm shell

    http://photosofwar.net/a-ferdinand-heavy-tank-destroyer-lies-destroyed-following-a-direct-hit-from-a-soviet-dive-bomber-pe-2-sometime-in-1943-on-the-eastern-front/

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    1. If only that was wrong...

      +1

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    2. According to the unit History (Combat History of Schwere Panzerjäger-Abteilung 653) it was blown up by its own crew to prevent it from getting captured.

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    3. Naga, thanks for pointing this out.

      Karlheinz Munch, "The combat history of German heavy anti-tank unit 653 in World War 2", page 123: two pictures (both Soviet) show two different, disabled Ferdinands; one disabled by anti-tank mine and abandoned and the other destroyed by its crew and also abandoned. Since this book is basically an operational diary of the unit, it is certain that above mentioned Ferdinand was indeed destroyed by its own crew (to avoid machine falling in Soviet hands) rather than artillery/bombers/whatever.

      Communist propaganda and revisionism strikes again...

      Delete
  19. Still you need masses of arty to stop tanks. There is a very good reason nations invested in AT guns, TDs and such: arty is not a reliable way of stopping tank assault. If real arty was at least half like WoT's arty there will no sense doing that, even doing tanks at all

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  20. This is a pretty good post containing a lot of information that I have to explain to people about how indirect fire works.

    One of the points you make in your post is that artillery will aim at a visible object with a known distance relative to the target and then change the bearing to the target. This is what kills me in WOT as in most cases; artillery is firing indirectly at locations it has no visible reference from.
    In that case the forward observer would give his location (8/10 digit grid coordinate) and the battery commander would use maps to zero in, and his ballistics table to determine elevation. Ballistics tables were only as accurate as the quality of the rounds being used. One gun fires for effect, and if it hits the battery fires.

    This "true" indirect fire is where I feel artillery needs work. The representation of the delay and inaccuracy of the FO and the quality of the propellant needs to be portrayed better in WOT. I feel the lower DMG/accuracy and increase of splash is a good start

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  21. Do you happen to have link at hand, I read that once, but have lost the link and can't find it with google?

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  22. This likely is not what you were looking for but it might be worth the look.
    Fire for Effect: Field Artillery and Close Air Support in the US Army, by historian John J. McGrath.
    http://usacac.army.mil/cac2/cgsc/carl/download/csipubs/mcgrath_fire.pdf

    ReplyDelete

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