Penetration (or Armor Penetration) is a game concept describing the ability of a projectile (a bullet, shell, or any other damage-inflicting object) to pass through layers of armor on a targeted vehicle. Each projectile has a certain chance of going through the armor on a specific unit. If it fails that chance, it will be deflected by the armor, either causing no damage or causing a significantly reduced amount. A projectile that succeeds in penetrating armor will cause full damage as normal. Firing at the rear or sides of a vehicle increases the chance of penetration (at least, most of the time).
In the First World War, the Machine Gun became one of the most terrifying weapons on the battlefield. Spewing plenty of bullets, it was capable of killing infantry by the dozens as they charged at it, and easily lay waste to the few trucks and other vehicles that existed on the battlefield. As a result, advancing armies were bound to sustain terrible casualties for every mile they took, and this eventually persuaded all sides in the conflict to entrench themselves and wage a very slow war of attrition.
This situation went on for almost three years, until the British developed a new and ingenious solution: a vehicle clad in thick layers of metal, so thick that bullets from a machine gun could not possibly hope to hurt the men inside. This vehicle, now known as a "Tank", eventually evolved into numerous armor-clad vehicles that performed various tasks on the battlefield - whether lightly armored trucks for ferrying infantry through enemy fire, or heavily-armored tanks meant to battle each other and raze enemy structures.
As tanks became commonplace, weapons to destroy them soon followed. Large, powerful cannons were developed that could lob explosive shells at these tanks, blowing the armor apart or at least causing damage to the propulsion or weapons systems. Naturally, tank armor got even heavier, and eventually a type of shell was developed that could go through the thick metal and explode with massive force inside. This is the story of armor and armor-piercing munitions, which is still being played out on the modern battlefield - with heavier tanks and larger guns to destroy them.
Company of Heroes implements this aspect of warfare in a system called "Penetration". Remarkably simple, it simulates the interaction between the various types of bullets and shells flying around the battlefield, and the armor that's ready to receive and deflect those munitions.
In the GameEdit
In Company of Heroes, this entire concept revolves around the "Penetration" value of different weapons. Each weapon's data in the game files contains a list of all units in the game, and has a specific "Penetration" value listed against each and every one of these units.
For example, the 75mm cannon on a Cromwell Tank, a medium-sized gun in all respects, has a Penetration value of 0.4 against a StuG IV, a 0.9 value against an Ostwind, and a 2.1 value against a Heavy Armored Car. By contrast, the 17 Pounder AT Gun's massive anti-tank weapon has a 2.4 Penetration value against the StuG, 5.56 against the Ostwind, and 12.95 against the Armored Car. By comparison, the Penetration values for a Vickers Machine Gun Emplacement are much lower - almost negligible - with only 0.04 against the Armored Car and even lower values against the other, heavier vehicles.
But what do these values mean?
These values represent the chance of the projectile fired by the weapon to go through the enemy vehicle's front armor, where a value of 1.0 means 100% chance, and a value of 0.0 means no chance at all. In the example above, when faced against a StuG IV, the Cromwell's gun has a chance of 40% to penetrate the stubby tank's front armor. The 17 Pounder would have a 240% chance (basically meaning that every shot will penetrate, of course), while for the Vickers HMG only one in every 25 bullets will actually do damage to the enemy tank (a 4% chance).
Every time a bullet or shell impacts with the enemy vehicle, it must roll against the Penetration value to see whether it managed to punch through the armor. If the roll is successful, the projectile goes through the armor and inflicts its full damage potential on the vehicle - corresponding with the damage value assigned to the weapon itself.However, if it fails this roll, the projectile will simply bounce off the enemy vehicle. Lighter projectiles, like bullets from an infantry weapon or machine gun, will usually cause absolutely no damage when this happens - they are just too weak to dent the metal. Other, heavier projectiles will actually cause damage to the target vehicle anyway, bending its armor a little just thanks to the awesome force of impact. This "deflection" behavior is specifically detailed for every projectile in the game, from the smallest SMG bullets to the largest artillery shells.
This is the general outline of the entire system, the interplay between armor and projectile. But as most experienced players know, in the field things can get a little more complicated.
Rear Armor PenetrationEdit
The uninitiated often ask: If thicker armor can stop larger projectiles, why don't they just put more armor on the tank? The answer is very simple of course: How much metal and armour are you willing to put on there? Because at a certain point, you reach incredible weights and sizes for tanks that just aren't practical anymore, as the Wehrmacht quickly discovered when they tried making their huge, impenetrable tanks. Such high tonnage made them clumsily and unwieldily slow, extremely costly to make so they couldn't produce very many of them, prone to mechanical breakdown because their mechanical systems couldn't handle the weight (there's a very popular running joke on the Internet that German tanks were the best, but that you could never make it to the frontline because your transmission would always break down), and ate a lot of what little precious fuel reserves Germany had by that point in the war. They couldn't cross a lot of bridges, since the bridges would collapse under their immense weight. Moving them around was a pain. Not to mention they were a spectacular target for aerial and naval bombardment.
So, slapping as much armour onto your tank as you can isn't a very bright idea. It needs a smart design and arrangement of what armour layout it's going to have. Therefore, the majority of armored vehicles aren't equally armoured and tough from all sides - usually, a tank will have it's toughest armour on the front, which it faces to the enemy, with the weakest being at the rear. This is true in Company of Heroes, and the principle is applied for all armoured vehicles, even for the ones that historically may have had similar or identical armour layout on all sides.
Therefore, the key to winning an engagement against armour is less about frontal attacks and brute force, and more about flanking the enemy to acquire shots at his weaker sides and rear.
How this works Edit
Just as weapons each have Penetration values against different targets, they also have what is called a Rear Penetration Multiplier. This is also unique for every weapon in the game and its corresponding target - exactly like Penetration values. This multiplier is applied to the weapon's normal or front penetration value, whenever attacking its target from the rear half.
Returning to our example from before, the Cromwell Tank's 75mm cannon has only a 40% chance of penetrating the front armor of a StuG IV with each shell it fires. This chance applies only when the Cromwell fires at the front of the StuG. When attacking the StuG from the rear, however, a Rear Penetration Multiplier of 5.0 is applied.
5.0 x 40% = 200%, meaning basically that every shot the Cromwell fires at the rear armor will penetrate!
Weaker weapons may have to fire at the target's rear armor to have any real chance of penetrating it. Other weapons, like the 75mm cannon above, are simply much more reliable from the rear than from the front, allowing the player to make a conscious choice as to whether he prefers a face-to-face confrontation, or to try a risky attempt to flank the enemy vehicle for the added penetration chance.
In almost all cases however, attacking an enemy vehicle's rear armor is preferable if it can be managed. All but the weakest weapons, which have virtually no chance to penetrate any armor, will benefit from attaining a flanking position.Note that it is not necessary to fire from directly behind the enemy to get the Rear Penetration Multiplier. It is applied whenever the shot lands on the rear half of the vehicle - indeed, sometimes, due to accuracy not always being consistent and game mechanics, a shot coming from the frontal arc of a vehicle can hit the rear-side armour (which the game counts as a rear armour hit). It might also be possible for players to manually aim at the rear armour on a vehicle with the Attack Ground order, allowing players to hit "rear" armour when engaging from the front.
An additional bonus to targeting a vehicle's rear is that it increases the chance of doing critical damage to the vehicle's engine. Most, if not all tanks keep their engine at the rear, where it is safer. If an enemy tank attacks their rear section, shots that penetrate the weaker rear armor may go into the engine, causing significant damage.
Engine damage and, if enough damage is accrued, engine kills, can be very useful. Destroying the mobility of a tank, or indeed of any vehicle, including jeeps and motorcycles, can severely impair its ability to carry out its mission. The obvious example here is the Jeep and the Motorcycle, which act as scouts. Cripple the engine and you significantly undermine their ability to scout and perform their tasks. Please do make note though that destroying the engine does not affect turn rate of a vehicle. In light of that, even though turn rate is unaffected and the tank can still face its front armour to its enemies, it is still a pretty crippling blow that will allow the enemy to secure a kill on it much quicker, since it's still pretty much rooted in position and a sitting duck - allowing it to still be flanked and circled regardless, something that wouldn't happen if it were able to back up and retreat. And since there will inevitably be more than one weapon attacking the tank, and you can only face your front armour to one attacker at a time, the tank's weaker side and rear armour will be opened up. Also, some weapons, like American sticky bombs, have greater chances of dealing engine damage.
Penetration vs. Range Edit
This game also implements penetration loss over range. Some specifics are detailed below.
Many of the best tank and anti-tank cannons in the game have very long ranges. Almost all tank cannons can engage targets just beyond their own sight-range, and the largest anti-tank guns like the 88mm Flak 36 AT/AA can fire way beyond that; nearly cross-court across the map.
However, long-range anti-tank combat has a significant drawback: the longer the shell has to fly through the air, the weaker it will be when it reaches its target. This is due to air-resistance, which works to slow down the shell as it flies. As a result, the Penetration value of most projectiles will slowly diminish while they make their way towards the target. In some cases, the end result is a significant reduction in Penetration against far-away targets - especially if the shell itself was not designed to fly that far.
Let's go right back to our Cromwell vs. StuG IV scenario to show how this can affect a battle.
- Let's say our Cromwell has spotted the StuG at a range of 40 meters. Both tanks begin exchanging gunfire, since they both have a range of 40 on their weapons. At this range, both guns will miss 1 in 4 shots, due to lack of accuracy. Each hit the Cromwell does make has only 40% chance of Penetrating the StuG's front armor. The StuG, on the other hand, will penetrate the Cromwell's armor with every shot that hits (it has a 120% chance to do so, which basically means "always penetrates"), but has a harder time hitting the Cromwell. On top of this, the Cromwell is tougher than the Stug, and can sustain more damage.
- All things told, both vehicles have a roughly equal chance of winning this engagement, and escaping by the skin of their teeth.
- However, both weapons suffer from a Penetration reduction due to the extreme range at which this battle is taking place. In fact, it makes penetration about 20% harder for both weapons.
- As a result, the chance for the Cromwell to penetrate the StuG's armor drops to about 33%, meaning that only 1 in 3 shots that hit will cause full damage. The StuG, on the other hand, drops to about 100% penetration: its shots will still chew through the Cromwell's front armor every single time.
- Unless luck intervenes, this puts the StuG at some advantage, and it is more likely to survive the confrontation.
This effect is more negligible with two medium tanks slugging it out as explained above, and much more important when a group of medium tanks are trying to take out a heavy tank, for instance. The disparity in penetration values means that every reduction can mean an earlier death. For this reason, tanks that are inferior to their opponents benefit from closing the distance. In the above example, for instance, the Cromwell can significantly increase its chances to come out victorious by closing the distance with the StuG - avoiding the Penetration penalty while still enjoying all the other perks it gets from being a Cromwell tank.
Note that for heavy tank-destroyers, this is often much less of an issue. The Penetration values on their guns are so high, that very little can be done to prevent them from penetrating the front armor of most vehicles.
Armor Piercing Rounds Edit
Up until World War I, firearms and cannons fired two general types of projectiles: solid, and high-explosive. The first is a simply ball or bullet made entirely out of metal, designed to deliver a lot of kinetic energy into its target. The second is supposed to explode, whether on impact or otherwise, delivering damage through the shockwave or through flying bits of shrapnel.
The invention of heavy armor required the development of projectiles that were specifically built to penetrate that armor and kill whatever is inside. This gave rise to Armor-Piercing Rounds.
The idea behind this type of ammunition is to create a specific shape and explosive charge that would concentrate all the damage on a tiny point, rather than spreading it out like high-explosive shells do. When the entire projectile's damage output is concentrated, it can pierce a small hole through even the thickest armor. The energy then travels through that hole and hopefully destroys whatever is on the other side of the armor, whether thanks to the incredible heat this generates, or by bits of the armor flying inwards.
In Company of Heroes, several weapons can load Armor-Piercing ammunition ("AP Rounds", for short) instead of their normal solid or explosive ammo. This boosts the weapon's Penetration value significantly, allowing it to have a better chance of penetrating armor, thus making the weapon more useful against heavier vehicles.
Units can obtain this bonus through various means. For some units, like the M1917 Browning Heavy Machine Gun Team, this is done by activating a temporary ability. Yet more vehicles may benefit from Command Upgrades or Global Upgrades purchased separately, and many units receive bonus Penetration when gaining Veterancy.
The M4 Sherman has a similar, related, permanent upgrade that swaps the main gun on it from an anti-infantry oriented, general-purpose 75mm gun with a large area of effect to an anti-armour oriented 76mm gun with higher Penetration and smaller area of effect.
Regardless of where the bonus comes from, it will normally increase Penetration against all targets, usually by multiplication. For example, if the weapon has a Penetration of 0.1 against a specific target (10% chance of penetration with each bullet), and gets a bonus multiplier of 5.0, it will now have a 50% chance of penetration (
0.1 x 5.0 = 0.5 or 50% chance).
In the majority of cases, increased penetration comes at the cost of reduced area damage. The shell is designed to direct all its energy on a small point of a target's armor, and any "spread" damage would defeat that purpose. Therefore, a shot that misses its target by even a small distance will cause little or no damage to any target. This is especially true for weapons that normally cause a large explosion (i.e. normally firing high-explosive shells), though these instead have the advantage of causing significant damage to soft targets even when they are not hit directly.